Diverse Seismic Imaging Created by the Seismic Explosion Experiment of the TAIGER Project

NASA Astrophysics Data System (ADS)

Wang, C.; Okaya, D.; Wu, F.; Yen, H.; Huang, B.; Liang, W.

2008-12-01

The TAIGER (TAiwan Integrated GEodynamics Research) project which examines the Taiwan orogeny includes five experiments: natural earthquake recording, man-made explosion recording, Magnetotelluic imaging, marine MCS and sea-land shooting, and deformation evolution modeling. During Feb-Mar 2008, the explosion experiment was carried out. Ten sources with 500~3000kg dynamite were detonated along two transects across northern and southern Taiwan. Over 600 PASSCAL Texans and 40 R-130 instruments record the signals over 100~300 km range. Additional arrays with 100 seismometers were deployed to collect north-south line and fan shoot data for 3D imaging. Furthermore, there are 9 ocean bottom seismometers (OBS) in the Taiwan Strait and two lines with 20 seismometers deployed on the mainland China side. A large volume of qualified data has been created. Except explosion signals, numerous local and regional earthquakes were also recorded even by the Texan instruments. The rich earthquake-explosion dataset now exists at the Institute of Earth Sciences, Academia Sinica operated by the Taiwan Earthquake Center (TEC). Preliminary examination of the data reveal crustal Pg, PmP, Pn and intermediate crustal reflection phases within the transect profiles and in the 3D cross-arrays. These data provide direct seismic imaging of the continental Moho under Taiwan and the sharp Moho root configuration associated with mountain building. Seismic tomography and raytrace methods reveal velocity structure consistent with convergence and vertical exhumation of the Central Ranges.

Investigation of intraplate seismicity near the sites of the 2012 major strike-slip earthquakes in the eastern Indian Ocean through a passive-source OBS experiment

NASA Astrophysics Data System (ADS)

Guo, L.; Lin, J.; Yang, H.

2017-12-01

The 11 April 2012 Mw8.6 earthquake off the coast of Sumatra in the eastern Indian Ocean was the largest strike-slip earthquake ever recorded. The 2012 mainshock and its aftershock sequences were associated with complex slip partitioning and earthquake interactions of an oblique convergent system, in a new plate boundary zone between the Indian and Australian plates. The detail processes of the earthquake interactions and correlation with seafloor geological structure, however, are still poorly known. During March-April 2017, an array of broadband OBS (ocean bottom seismometer) were deployed, for the first time, near the epicenter region of the 2012 earthquake sequence. During post-expedition data processing, we identified 70 global earthquakes from the National Earthquake Information Center (NEIC) catalog that occurred during our OBS deployment period. We then picked P and S waves in the seismic records and analyzed their arrival times. We further identified and analyzed multiple local earthquakes and examined their relationship to the observed seafloor structure (fracture zones, seafloor faults, etc.) and the state of stresses in this region of the eastern Indian Ocean. The ongoing analyses of the data obtained from this unique seismic experiment are expected to provide important constraints on the large-scale intraplate deformation in this part of the eastern Indian Ocean.

Real-time seismic data from the coastal ocean

USGS Publications Warehouse

Frye, D.; ten Brink, Uri S.; Paul, W.; Peal, K.; Von Der Heydt, K.

2003-01-01

A moored-buoy system for collecting real-time seismic data from the coastal ocean has been developed and will be deployed for its initial field trial in the fall of 2003. The key component in this moored system is an ultra-stretchy mooring hose that provides compliance for waves and currents and protects the electrical conductors connecting an Ocean Bottom Seismometer (OBS) to a surface buoy from the effects of bending and stretching. This hose is able to stretch to more than twice its unstretched length of 30 m without putting excessive strain on the electrical conductors embedded in its wall. In the initial trials of this system, the OBS will be deployed on the bottom in 40 m of water and connected to the mooring hose through a cable on the seafloor. It will transmit continuous data at a rate of about 5,000 bps to a radio link in the surface buoy. A repeater modem located at the Gay Head lighthouse on Martha's Vineyard about 18 km from the mooring site will receive the transmissions and forward the data to our laboratory at WHOI, about 46 km distant. A GPS receiver on the surface buoy will be configured to send accurate and synchronized time to the OBS on the seafloor, which will make it possible to include data from these undersea systems in the existing seismic data network without the need for any preprocessing. Power to operate the RF link and the OBS will be supplied by solar panels and rechargeable batteries on the surface buoy.

Shoreline-crossing shear-velocity structure of the Juan de Fuca plate and Cascadia subduction zone from surface waves and receiver functions

NASA Astrophysics Data System (ADS)

Janiszewski, Helen; Gaherty, James; Abers, Geoffrey; Gao, Haiying

2017-04-01

The Cascadia subduction zone (CSZ) is the site of the onshore-offshore Cascadia Initiative, which deployed seismometers extending from the Juan de Fuca ridge to the subduction zone and onshore beyond the volcanic arc. This array allows the unique opportunity to seismically image the evolution and along-strike variation of the crust and mantle of the entire CSZ. We compare teleseismic receiver functions, ambient-noise Rayleigh-wave phase velocities in the 10-20 s period band, and earthquake-source Rayleigh-wave phase velocities from 20-100 s, to determine shear-velocity structure in the upper 200 km. Receiver functions from both onshore and shallow-water offshore sites provide constraints on crustal and plate interface structure. Spectral-domain fitting of ambient-noise empirical Green's functions constrains shear velocity of the crust and shallow mantle. An automated multi-channel cross-correlation analysis of teleseismic Rayleigh waves provides deeper lithosphere and asthenosphere constraints. The amphibious nature of the array means it is essential to examine the effect of noise variability on data quality. Ocean bottom seismometers (OBS) are affected by tilt and compliance noise. Removal of this noise from the vertical components of the OBS is essential for the teleseismic Rayleigh waves; this stabilizes the output phase velocity maps particularly along the coastline where observations are predominately from shallow water OBS. Our noise-corrected phase velocity maps reflect major structures and tectonic transitions including the transition from high-velocity oceanic lithosphere to low-velocity continental lithosphere, high velocities associated with the subducting slab, and low velocities beneath the ridge and arc. We interpret the resulting shear-velocity model in the context of temperature and compositional variation in the incoming plate and along the strike of the CSZ.

Shoreline-Crossing Shear-Velocity Structure of the Juan de Fuca Plate and Cascadia Subduction Zone from Surface Waves and Receiver Functions

NASA Astrophysics Data System (ADS)

Janiszewski, H. A.; Gaherty, J. B.; Abers, G. A.; Gao, H.

2016-12-01

The Cascadia subduction zone (CSZ) is the site of the onshore-offshore Cascadia Initiative, which deployed seismometers extending from the Juan de Fuca ridge to the subduction zone and onshore beyond the volcanic arc. This array allows the unique opportunity to seismically image the evolution and along-strike variation of the crust and mantle of the entire CSZ. We compare teleseismic receiver functions, ambient-noise Rayleigh-wave phase velocities in the 10-20 s period band, and earthquake-source Rayleigh-wave phase velocities from 20-100 s, to determine shear-velocity structure in the upper 200 km. Receiver functions from both onshore and shallow-water offshore sites provide constraints on crustal and plate interface structure. Spectral-domain fitting of ambient-noise empirical Green's functions constrains shear velocity of the crust and shallow mantle. An automated multi-channel cross-correlation analysis of teleseismic Rayleigh waves provides deeper lithosphere and asthenosphere constraints. The amphibious nature of the array means it is essential to examine the effect of noise variability on data quality. Ocean bottom seismometers (OBS) are affected by tilt and compliance noise. Removal of this noise from the vertical components of the OBS is essential for the teleseismic Rayleigh waves; this stabilizes the output phase velocity maps particularly along the coastline where observations are predominately from shallow water OBS. Our noise-corrected phase velocity maps reflect major structures and tectonic transitions including the transition from high-velocity oceanic lithosphere to low-velocity continental lithosphere, high velocities associated with the subducting slab, and low velocities beneath the ridge and arc. We interpret the resulting shear-velocity model in the context of temperature and compositional variation in the incoming plate and along the strike of the CSZ.

Development of compact long-term broadband ocean bottom seismometer for seafloor observation of slow earthquakes

NASA Astrophysics Data System (ADS)

Yamashita, Y.; Shinohara, M.; Yamada, T.; Shiobara, H.

2017-12-01

It is important to understand coupling between plates in a subduction zone for studies of earthquake generation. Recently low frequency tremor and very low frequency earthquake (VLFE) were discovered in plate boundary near a trench. These events (slow earthquakes) in shallow plate boundary should be related to slow slip on a plate boundary. For observation of slow earthquakes, Broad Band Ocean Bottom Seismometer (BBOBS) is useful, however a number of BBOBSs are limited due to cost. On the other hand, a number of Long-term OBSs (LT-OBSs) with recording period of one year are available. However, the LT-OBS has seismometer with a natural period of 1 second. Therefore frequency band of observation is slightly narrow for slow earthquakes. Therefore we developed a compact long-term broad-band OBS by replacement of the seismic sensor of the LT-OBSs to broadband seismometer.We adopted seismic sensor with natural period of 20 seconds (Trillium Compact Broadband Seismometer, Nanometrics). Because tilt of OBS on seafloor can not be controlled due to free-fall, leveling system for seismic sensor is necessary. The broadband seismic senor has cylinder shape with diameter of 90 mm and height of 100 mm, and the developed levelling system can mount the seismic sensor with no modification of shape. The levelling system has diameter of 160 mm and height of 110 mm, which is the same size as existing levelling system of the LT-OBS. The levelling system has two horizontal axes and each axis is driven by motor. Leveling can be performed up to 20 degrees by using micro-processor (Arduino). Resolution of levelling is less than one degree. The system immediately starts leveling by the power-on of controller. After levelling, the the seismic senor is powered and the controller records angles of levelling to SD RAM. Then the controller is shut down to consume no power. Compact long-term broadband ocean bottom seismometer is useful for observation of slow earthquakes on seafloor. In addition, seafloor observations of teleseismic events and deep earthquakes to estimate seismic structure of deep regions and observations of submarine volcanoes are expected.

Earth's crust model of the South-Okhotsk Basin by wide-angle OBS data

NASA Astrophysics Data System (ADS)

Kashubin, Sergey N.; Petrov, Oleg V.; Rybalka, Alexander V.; Milshtein, Evgenia D.; Shokalsky, Sergey P.; Verba, Mark L.; Petrov, Evgeniy O.

2017-07-01

Deep seismic studies of the Sea of Okhotsk region started in late 1950s. Since that time, wide-angle reflection and refraction data on more than two dozen profiles were acquired. Only five of those profiles either crossed or entered the deep-water area of the South-Okhotsk Basin (also known as the Kuril Basin or the South-Okhotsk Deep-Water Trough). Only P-waves were used to develop velocity-interface models in all the early research. Thus, all seismic and geodynamic models of the Okhotsk region were based only on the information on compressional waves. Nevertheless, the use of Vp/Vs ratio in addition to P-wave velocity allows discriminating felsic and mafic crustal layers with similar Vp values. In 2007 the Russian seismic service company Sevmorgeo acquired multi-component data with ocean bottom seismometers (OBS) along the 1700-km-long north-south 2-DV-M Profile. Only P-wave information was used previously to develop models for the entire profile. In this study, a multi-wave processing, analysis, and interpretation of the OBS data are presented for the 550-km-long southern segment of this Profile that crosses the deep-water South-Okhotsk Basin. Within this segment 50 seismometers were deployed with nominal OBS station spacing of 10-12 km. Shot point spacing was 250 m. Not only primary P-waves and S-waves but also multiples and P-S, S-P converted waves were analyzed in this study to constrain velocity-interface models by means of travel time forward modeling. In offshore deep seismic studies, thick water layer hinders an estimation of velocities in the sedimentary cover and in the upper consolidated crust. Primarily, this is due to the fact that refracted waves propagating in low-velocity solid upper layers interfere with high-amplitude direct water wave. However, in multi-component measurements with ocean bottom seismometers, it is possible to use converted and multiple waves for velocity estimations in these layers. Consequently, one can obtain P- and S-waves velocity models of the sedimentary strata and the upper consolidated crust. Velocity values in the upper consolidated crust beneath the South-Okhotsk Basin (Vp = 5.50-5.80 km/s, Vp/Vs = 1.74-1.76) allow interpretation of this 2.5-3.5-km-thick layer to be consistent with a felsic (granodioritic) crust. These results suggest that the Earth's crust in this region can be considered continental in nature, rather than previously accepted oceanic crust. Even though, the crust is thinned and stretched at this location.

Unusual Signals Recorded by Ocean Bottom Seismometers in the Caldera of Deception Island Volcano: Biological Activity or Hydrothermally Generated Seismicity?

NASA Astrophysics Data System (ADS)

Bowman, D. C.; Wilcock, W. S.

2011-12-01

As part of an active source land-sea tomography experiment, ocean bottom seismometers (OBSs) were deployed at Deception Island Volcano, Antarctica, in January 2005. Following the tomography study, three OBSs were left for a month inside the flooded caldera and ten on the outer slopes of the volcano to record seismo-volcanic signals. The OBS sensor package included three-orthogonal 1-Hz geophones but no hydrophone. The OBSs were deployed in water depths of 125 to 143 m inside the caldera and at depths of 119 to 475 m on the volcano's flanks. Only two volcano-tectonic earthquakes and three long period events were recorded by the network. However, the OBSs inside the caldera recorded over 4,500 unusual seismic events. These were detected by only one station at a time and were completely absent from OBSs on the flank of the volcano and from land stations deployed on the island. The signals had a dominant frequency of 5 Hz and were one to ten seconds long. Event activity in the caldera was variable with the number of events per hour ranging from 0 up to 60 and the level of activity decreasing slightly over the study period. We categorize the signals into three types based on waveform characteristics. Type 1 events have an impulsive onset and last 1 to 2 s with characteristics that are consistent with the impulse response of a poorly coupled OBS. Type 2 events typically last 2 to 4 s and comprise a low amplitude initial arrival followed less than a second later by a more energetic second phase that looks a Type 1 event. Type 3 events last up to 10 s and have more complex waveforms that appear to comprise several arrivals of varying amplitudes. Type 1 events are similar to the 'fish-bump' signals reported from previous studies that attributed them to biological activity. The consistent timing and relative amplitudes of the two arrivals for Type 2 events are difficult to explain by animals randomly touching the OBSs. Type 3 events are quite similar in frequency, duration, and signal characteristics to long-period seismic events recorded by an onshore seismic array deployed in an earlier study at Deception Island. Particle motions suggest that Type 3 events may be surface waves while the particle motions for Type 1 and Type 2 events are ambiguous and unlike any signals recorded by land arrays at the volcano. Binomial tests of the event distribution show no significant changes in the rate of events with time of day that would be indicative of a biological source. Since the events are entirely absent in biologically productive waters outside the caldera, we postulate that they may be volcanic signals related to hydrothermal flow across the seafloor in the flooded caldera of Deception Island. Future OBS deployments at Deception Island should include a hydrophone to discriminate unambiguously between biological and volcanic signals.

A comparison between two permanent broad band ocean bottom seismometers in the western Mediterranean Sea

NASA Astrophysics Data System (ADS)

Frontera, T.; Deschamps, A.; Ugalde, A.; Jara, J. A.; Hello, Y.; Goula, X.; Olivera, C.

2009-04-01

The aim of this work is to compare two permanent broad band ocean bottom seismometers (OBS) in terms of noise conditions by taking to account their similar instrumentation types, but their very different site characteristics. Both OBS stations have Güralp CMG-3T three component broad band sensors and differential pressure gauges (DPG). The first sensor operates since August 2005 under the framework of a research project that aims to improve the knowledge of the seismicity and seismic risk in the Tarragona region (north eastern Spain). This pioneering project in Spain is being carried out by the Institut Geològic de Catalunya (IGC) and the Observatori de l'Ebre, in collaboration with the Spanish oil company Repsol Investigaciones Petrolíferas, and is being financed by the Ministerio de Educación y Ciencia (CASABLANCA REN2003-06577), FEDER funding, the IGC and the Institut Cartogràfic de Catalunya. The OBS is installed inside the security perimeter of the Casablanca oil platform, which is located 40 km offshore Tarragona. The sensors are submerged at about 400 m to the SW of the oil platform at about 150 m in depth. Data are digitized on-site and are transmitted through a submarine cable to the platform, where they are recorded. In July 2007 some improvements were made: i) the OBS was completely buried and the DPG was moved about 10 m away from the OBS; and ii) via satellite signal transmission was implemented, which allowed to have continuous and real time data in Barcelona so that the OBS could be integrated into the Catalan Seismic Network. The second seismometer operates in the frame of the Antares neutrino telescope project developed in Liguria Sea. Geoazur is carrying out the project of deployment of a broad band seismological instrument in the aim of developing the permanent sea floor observation knowledge necessary to characterize Ligurian Sea seismicity and seismic risk along French Riviera coast (SE France). The operation was facilitated by the deployment of an opto-electrical cable to provide power and data transmission from the coast to a recording point at 2550 m in depth and 15km south to Porquerolles Island in the frame of the Antares neutrino telescope project. The program was founded in the 2002-2006 CPER (State-Region Research plan) by PACA region and CNRS/INSU and in the Antares collaboration which is responsible of all the marine operations on the site. The OBS and the DPG were set up by the ROV "Victor" from Ifremer (French Research Institute for Exploitation of the Sea) and partially buried; levelling and orientation were performed directly on the site. The instrument was running from April 2005 to April 2007. In April 2006 the sensor was completely buried. Data transmitted in quasi real time to Geoazur were integrated to the regional data center. In April 2007 the sensor was retrieved and reinstalled with data transmission protocol modification in October 2008. A water leak detected in December forced to cut the alimentation in January 2009. Because both sensors have not operated over the same time period, two different periods have been analysed: 2006 for the Antares OBS and 2008 for the Casablanca's one. In this way we are able to make a comparison of the noise behaviour by observing also the seasonal evolution. As observed on most of the ocean floor observatories, the noise is quite large on all components for both OBS. In general, the Antares OBS shows a better behaviour than the Casablanca OBS, due to the more favourable site conditions. Both OBS have been reinstalled to ameliorate some site condition deficiencies, which has basically affected the low frequency band, between 0.008 and 0.07 Hz. After the reinstallations, the noise conditions have improved at least 10 dB. A comparison of the power spectral density (PSD) curves for both stations concerning the periods after the reinstallations of the OBS show that, at low frequencies, the vertical component PSD curve for the Casablanca OBS is about 20 dB higher than the Antares PSD curve. However, both fall in between Peterson's new high (NHNM) and low (NLNM) noise models. The PSD of the horizontal components for the Casablanca OBS in the same frequency band is higher than that of the vertical component and is also higher than the NHNM. For the Antares OBS the PSD curves of the horizontal components are higher than the Antares vertical component PSD curve, but they lie inside the margins marked by Peterson's models. On the microseismic band, between 0.07 and 2 Hz, quieter PSD curves for the Antares OBS than for the Casablanca's one are observed. Nevertheless, the primary microseismic peak is not seen on the Antares PSD curves, whereas it can be observed on the vertical component PSD curve for the Casablanca OBS. As for the secondary microseimic peak, it is much better defined on the Antares PSD curves than for the Casablanca case for all components. Finally, at high frequencies between 2 and 50 Hz, high noise levels are observed for all components and both OBS.

Classifying seismic noise and sources from OBS data using unsupervised machine learning

NASA Astrophysics Data System (ADS)

Mosher, S. G.; Audet, P.

2017-12-01

The paradigm of plate tectonics was established mainly by recognizing the central role of oceanic plates in the production and destruction of tectonic plates at their boundaries. Since that realization, however, seismic studies of tectonic plates and their associated deformation have slowly shifted their attention toward continental plates due to the ease of installation and maintenance of high-quality seismic networks on land. The result has been a much more detailed understanding of the seismicity patterns associated with continental plate deformation in comparison with the low-magnitude deformation patterns within oceanic plates and at their boundaries. While the number of high-quality ocean-bottom seismometer (OBS) deployments within the past decade has demonstrated the potential to significantly increase our understanding of tectonic systems in oceanic settings, OBS data poses significant challenges to many of the traditional data processing techniques in seismology. In particular, problems involving the detection, location, and classification of seismic sources occurring within oceanic settings are much more difficult due to the extremely noisy seafloor environment in which data are recorded. However, classifying data without a priori constraints is a problem that is routinely pursued via unsupervised machine learning algorithms, which remain robust even in cases involving complicated datasets. In this research, we apply simple unsupervised machine learning algorithms (e.g., clustering) to OBS data from the Cascadia Initiative in an attempt to classify and detect a broad range of seismic sources, including various noise sources and tremor signals occurring within ocean settings.

Seismic investigation of gas hydrates in the Gulf of Mexico: 2013 multi-component and high-resolution 2D acquisition at GC955 and WR313

USGS Publications Warehouse

Haines, Seth S.; Hart, Patrick E.; Shedd, William W.; Frye, Matthew

2014-01-01

The U.S. Geological Survey led a seismic acquisition cruise at Green Canyon 955 (GC955) and Walker Ridge 313 (WR313) in the Gulf of Mexico from April 18 to May 3, 2013, acquiring multicomponent and high-resolution 2D seismic data. GC955 and WR313 are established, world-class study sites where high gas hydrate saturations exist within reservoir-grade sands in this long-established petroleum province. Logging-while-drilling (LWD) data acquired in 2009 by the Gulf of Mexico Gas Hydrates Joint Industry Project provide detailed characterization at the borehole locations, and industry seismic data provide regional- and local-scale structural and stratigraphic characterization. Significant remaining questions regarding lithology and hydrate saturation between and away from the boreholes spurred new geophysical data acquisition at these sites. The goals of our 2013 surveys were to (1) achieve improved imaging and characterization at these sites and (2) refine geophysical methods for gas hydrate characterization in other locations. In the area of GC955 we deployed 21 ocean-bottom seismometers (OBS) and acquired approximately 400 km of high-resolution 2D streamer seismic data in a grid with line spacing as small as 50 m and along radial lines that provide source offsets up to 10 km and diverse azimuths for the OBS. In the area of WR313 we deployed 25 OBS and acquired approximately 450 km of streamer seismic data in a grid pattern with line spacing as small as 250 m and along radial lines that provide source offsets up to 10 km for the OBS. These new data afford at least five times better resolution of the structural and stratigraphic features of interest at the sites and enable considerably improved characterization of lithology and the gas and gas hydrate systems. Our recent survey represents a unique application of dedicated geophysical data to the characterization of confirmed reservoir-grade gas hydrate accumulations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slad, George William; Merchant, Bion J.

The Seismo - Hydroacoustic Data Acquisition System (SHDAS) is undergoing evaluation in preparation for its engineering, development, and deployment by the U.S Navy as an ocean bottom seismic monitoring system. At the current stage of development, the production seismometers are being evaluated to confirm their performance prior to packaging and assembly for deployment. The testing of the seismometers is being conducted at the Pinon Flats Observatory (PFO) , supervised by Sandia National Laboratories, U.S Navy, and RP Kromer Consulting. SNL will conduct evaluation of the collected seismometer data and comment on the performance of the seismometers.

Ocean bottom seismometer: design and test of a measurement system for marine seismology.

PubMed

Mànuel, Antoni; Roset, Xavier; Del Rio, Joaquin; Toma, Daniel Mihai; Carreras, Normandino; Panahi, Shahram Shariat; Garcia-Benadí, A; Owen, Tim; Cadena, Javier

2012-01-01

The Ocean Bottom Seismometer (OBS) is a key instrument for the geophysical study of sea sub-bottom layers. At present, more reliable autonomous instruments capable of recording underwater for long periods of time and therefore handling large data storage are needed. This paper presents a new Ocean Bottom Seismometer designed to be used in long duration seismic surveys. Power consumption and noise level of the acquisition system are the key points to optimize the autonomy and the data quality. To achieve our goals, a new low power data logger with high resolution and Signal-to-Noise Ratio (SNR) based on Compact Flash memory card is designed to enable continuous data acquisition. The equipment represents the achievement of joint work from different scientific and technological disciplines as electronics, mechanics, acoustics, communications, information technology, marine geophysics, etc. This easy to handle and sophisticated equipment allows the recording of useful controlled source and passive seismic data, as well as other time varying data, with multiple applications in marine environment research. We have been working on a series of prototypes for ten years to improve many of the aspects that make the equipment easy to handle and useful to work in deep-water areas. Ocean Bottom Seismometers (OBS) have received growing attention from the geoscience community during the last forty years. OBS sensors recording motion of the ocean floor hold key information in order to study offshore seismicity and to explore the Earth's crust. In a seismic survey, a series of OBSs are placed on the seabed of the area under study, where they record either natural seismic activity or acoustic signals generated by compressed air-guns on the ocean surface. The resulting data sets are subsequently used to model both the earthquake locations and the crustal structure.

Ocean Bottom Seismometer: Design and Test of a Measurement System for Marine Seismology

PubMed Central

Mànuel, Antoni; Roset, Xavier; Del Rio, Joaquin; Toma, Daniel Mihai; Carreras, Normandino; Panahi, Shahram Shariat; Garcia-Benadí, A.; Owen, Tim; Cadena, Javier

2012-01-01

The Ocean Bottom Seismometer (OBS) is a key instrument for the geophysical study of sea sub-bottom layers. At present, more reliable autonomous instruments capable of recording underwater for long periods of time and therefore handling large data storage are needed. This paper presents a new Ocean Bottom Seismometer designed to be used in long duration seismic surveys. Power consumption and noise level of the acquisition system are the key points to optimize the autonomy and the data quality. To achieve our goals, a new low power data logger with high resolution and Signal–to-Noise Ratio (SNR) based on Compact Flash memory card is designed to enable continuous data acquisition. The equipment represents the achievement of joint work from different scientific and technological disciplines as electronics, mechanics, acoustics, communications, information technology, marine geophysics, etc. This easy to handle and sophisticated equipment allows the recording of useful controlled source and passive seismic data, as well as other time varying data, with multiple applications in marine environment research. We have been working on a series of prototypes for ten years to improve many of the aspects that make the equipment easy to handle and useful to work in deep-water areas. Ocean Bottom Seismometers (OBS) have received growing attention from the geoscience community during the last forty years. OBS sensors recording motion of the ocean floor hold key information in order to study offshore seismicity and to explore the Earth’s crust. In a seismic survey, a series of OBSs are placed on the seabed of the area under study, where they record either natural seismic activity or acoustic signals generated by compressed air-guns on the ocean surface. The resulting data sets are subsequently used to model both the earthquake locations and the crustal structure. PMID:22737032

OBSIP: An Evolving Facility for the Future of Geoscience

NASA Astrophysics Data System (ADS)

Evers, B.; Lodewyk, J. A.

2013-12-01

The Ocean Bottom Seismograph Instrument Pool 'OBSIP' was founded in 1999 as a National Science Foundation (NSF) sponsored instrument facility that provides ocean bottom seismometers and technical support for research in the areas of marine geology, seismology, and geodynamics. OBSIP provides both short period instruments (for active source seismic refraction studies) and long period instruments (for long term passive experiments). OBSIP is comprised of three Institutional Instrument Contributors - Lamont Doherty Earth Observatory (LDEO), Scripps Institution of Oceanography (SIO), and Woods Hole Oceanographic Institution (WHOI), each of whom contribute instruments and technical support to the pool. In 2012, NSF funded the Incorporated Research Institutions of Seismology (IRIS) to develop an OBSIP Management Office. Through the management office, IRIS will bring is extensive experience in managing facilities (PASSCAL instrument center), supporting large research experiments (Earthscope), and providing high quality data through the DMC to OBSIP. In the past year, OBSIP has provided instruments for eight experiments and supported over 20 research cruises recovering and/or deploying instruments. The most extensive OBSIP experiment in the past few years has been the Cascadia Initiative. The Cascadia Initiative is an onshore/offshore seismic and geodetic experiment deployed in the Pacific Northwest to study questions surrounding the evolution of the Juan de Fuca plate and the Gorda plate. As part of the American Recovery and Reinvestment Act, OBSIP IIC's built 60 new ocean bottom seismometers. Both LDEO and SIO designed new seismometer packages to withstand trawling by local fisherman for deployment in shallow areas. The Cascadia Initiative has required close cooperation between the OBSIP, the Deep Submergence Facility, the University National Oceanographic Laboratory System (who coordinates ship schedules for the cruises), and the Cascadia Initiative Expedition Team. At the recent OBSIP Workshop, members from the scientific community met to share scientific results and determine how OBS instrumentation can better serve the scientific community. The OBSIP Management Office is developing a comprehensive Data Quality Plan that includes all steps of the data collection process, from instrument design to quality controlling data after it is uploaded to the Data Management Center. OBSIP continues to evolve as it works to better serve the scientific community and the public.

Seismic structure from multi-channel seismic reflection and wide-angle data of Transect 0E in the Southern Gulf of California

NASA Astrophysics Data System (ADS)

Paramo, P.; Holbrook, W.; Brown, H.; Lizarralde, D.; Fletcher, J.; Umhoefer, P.; Kent, G.; Harding, A.; Gonzalez, A.; Axen, G.

2005-12-01

We present a velocity model from wide-angle data along with coincident prestack depth migration sections from seismic reflection data collected in the southern Gulf of California. Transect 0E runs NE to SW from the hills of Sierra Madre in mainland Mexico near Mazatlan to approximately 115 km into Gulf of California waters. Wide-angle data were recorded by 9 ocean bottom seismometers, deployed by the R/V New Horizon and 10 Reftek seismometers located along onshore extension of the transect. The average spacing for the OBS and Refteks is ~12 km and shots were fired from the R/V Maurice Ewing at 150 m intervals. Transect 0E crosses what it is believed to be extended continental crust and lies in the initial direction of extension characteristic of the proto-gulf. Preliminary results from the velocity model show upper crustal velocities of 6.1-6.3 km/s and lower crustal velocities of 6.7-7.0 km/s along the entire transect. Seismic velocities and crustal thicknesses observed along transect 0E are characteristic of non-volcanic margins.

Wave equation datuming applied to marine OBS data and to land high resolution seismic profiling

NASA Astrophysics Data System (ADS)

Barison, Erika; Brancatelli, Giuseppe; Nicolich, Rinaldo; Accaino, Flavio; Giustiniani, Michela; Tinivella, Umberta

2011-03-01

One key step in seismic data processing flows is the computation of static corrections, which relocate shots and receivers at the same datum plane and remove near surface weathering effects. We applied a standard static correction and a wave equation datuming and compared the obtained results in two case studies: 1) a sparse ocean bottom seismometers dataset for deep crustal prospecting; 2) a high resolution land reflection dataset for hydrogeological investigation. In both cases, a detailed velocity field, obtained by tomographic inversion of the first breaks, was adopted to relocate shots and receivers to the datum plane. The results emphasize the importance of wave equation datuming to properly handle complex near surface conditions. In the first dataset, the deployed ocean bottom seismometers were relocated to the sea level (shot positions) and a standard processing sequence was subsequently applied to the output. In the second dataset, the application of wave equation datuming allowed us to remove the coherent noise, such as ground roll, and to improve the image quality with respect to the application of static correction. The comparison of the two approaches evidences that the main reflecting markers are better resolved when the wave equation datuming procedure is adopted.

Excitation and Propagation of Short-Period Surface Waves in Young Seafloor

DTIC Science & Technology

2000-09-01

These waves are essentially the equivalent of Lg in continental settings, although because there is no granite in the oceanic crust, they might better...attenuated, they stand out above the noise level as one of the most prominent signals on ocean -bottom seismometers (OBS). In the MELT Experiment, 51 ocean ... ocean -bottom seismometers Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of information is

Correction of clock errors in seismic data using noise cross-correlations

NASA Astrophysics Data System (ADS)

Hable, Sarah; Sigloch, Karin; Barruol, Guilhem; Hadziioannou, Céline

2017-04-01

Correct and verifiable timing of seismic records is crucial for most seismological applications. For seismic land stations, frequent synchronization of the internal station clock with a GPS signal should ensure accurate timing, but loss of GPS synchronization is a common occurrence, especially for remote, temporary stations. In such cases, retrieval of clock timing has been a long-standing problem. The same timing problem applies to Ocean Bottom Seismometers (OBS), where no GPS signal can be received during deployment and only two GPS synchronizations can be attempted upon deployment and recovery. If successful, a skew correction is usually applied, where the final timing deviation is interpolated linearly across the entire operation period. If GPS synchronization upon recovery fails, then even this simple and unverified, first-order correction is not possible. In recent years, the usage of cross-correlation functions (CCFs) of ambient seismic noise has been demonstrated as a clock-correction method for certain network geometries. We demonstrate the great potential of this technique for island stations and OBS that were installed in the course of the Réunion Hotspot and Upper Mantle - Réunions Unterer Mantel (RHUM-RUM) project in the western Indian Ocean. Four stations on the island La Réunion were affected by clock errors of up to several minutes due to a missing GPS signal. CCFs are calculated for each day and compared with a reference cross-correlation function (RCF), which is usually the average of all CCFs. The clock error of each day is then determined from the measured shift between the daily CCFs and the RCF. To improve the accuracy of the method, CCFs are computed for several land stations and all three seismic components. Averaging over these station pairs and their 9 component pairs reduces the standard deviation of the clock errors by a factor of 4 (from 80 ms to 20 ms). This procedure permits a continuous monitoring of clock errors where small clock drifts (1 ms/day) as well as large clock jumps (6 min) are identified. The same method is applied to records of five OBS stations deployed within a radius of 150 km around La Réunion. The assumption of a linear clock drift is verified by correlating OBS for which GPS-based skew corrections were available with land stations. For two OBS stations without skew estimates, we find clock drifts of 0.9 ms/day and 0.4 ms/day. This study salvages expensive seismic records from remote regions that would be otherwise lost for seismicity or tomography studies.

Biological interference of optical backscatterance sensors in Tampa Bay, Florida

USGS Publications Warehouse

Schoellhamer, D.H.

1993-01-01

Optical backscatterance (OBS, D&A Instruments, Inc.1 1 Use of brand, firm, or trade names in this paper is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.) sensors for measuring suspended-solids concentrations have been deployed in Tampa Bay to monitor resuspension of bottom sediments. This paper describes biological factors that affected the OBS sensors deployed in Tampa Bay and discusses deployment strategies that minimize biological interference. Phytoplankton may interfere with the OBS sensors when the suspended-solids concentration is near or below the sensor response threshold. Fish swimming in front of the OBS sensors caused spikes in the OBS sensor output, so the median average was more appropriate than the mean average. An algal slime on the OBS sensors caused excessive backscatterance that dominated the backscatterance from suspended material. Because of the fouling problem, deployments were limited to less than a week, and OBS sensors were cleaned daily, if possible. Calibration of OBS sensors with water samples collected from Tampa Bay was satisfactory when biological interference was not significant. When properly deployed, the OBS sensors can successfully monitor sediment resuspension in Tampa Bay and similar subtropical estuaries. ?? 1993.

Analysis on typhoon-induced microseisms from ocean bottom seismometer array

NASA Astrophysics Data System (ADS)

Lee, Tzu-Chuan; Lin, Jing-Yi

2013-04-01

Ocean-bottom seismometer (OBS) is usually used for active sources and passive listening experiments, such as air guns, explosives, earthquakes and other signals. In fact, the seismometer records not only the seismic waveforms but also noises generated by winds, waves, tides and other external forces. From the end of August to early September 2011, 15 OBSs were deployed offshore northeastern Taiwan for a recording period of about 20 days. At the end of August, the typhoon NANMADOL formed in the western Pacific and moved northwestward from the East Philippines and finally landed on the island of Taiwan. Due to storms or pressure changes caused by the typhoon, elastic waves would be directly or indirectly produced and recorded by the seismometers. In this study, by analyzing the seismic signals collected by the OBSs and the BATS stations, we investigate the influence induced by the changes of typhoon path and intensity on the submarine seismic noises. Preliminary results indicate that the seismic energy change related to the typhoon occurred mainly at 0.2-0.5 Hz, which is a relatively low frequency compared to that of earthquakes. The amplitude of this low-frequency noise increased when the distance between the typhoon and seismometer decreased. By comparing the seismic waves with the data collected from the marine weather buoy, we observed a positive correlation between the power of the low frequency microseisms and the wave height. This clearly indicates that the typhoon was the main source of microseisms during their passing. Owing to the ocean waves generated by the typhoon, the pressure altered by the water column change and recorded by the seismometers as seismic waves before being transmitted to the sea?oor. The spectrum analysis shows the presence of a high energy signals at 0.2-1 Hz with a period of about 12 hours which could be related to the tidal movements. In addition, the amplitude of the recorded microseisms is also affected by the depth of seismometers. In general, the deeper the seismometer is located, the smaller the amplitude of microseisms it recorded. All these observations show the seismic signal can respond to the wave and wind changes. However, some exceptions, probably induced by site effect, are observed. Analysis based on the data recorded by hydrophones and inland stations displays consistent results with that of geophones, showing that ocean wave heights appear to be the main origin of the low frequency microseisms signals. Therefore, we suggest that the low frequency ground motions are mostly induced by nearby water pressure ?elds, and transmitted through the rock to the stations.

The NEPTUNE Canada Seismograph Network

NASA Astrophysics Data System (ADS)

Rogers, G. C.; Meldrum, R.; Baldwin, R.; Rosenberger, A.; Mulder, T.

2009-12-01

NEPTUNE Canada is the world’s first large regional cable-linked, multi-disciplinary scientific seafloor observatory. In the fall of 2007 an 800 kilometer ring of powered fibre optic cable was laid on the seafloor over the northern part of the Juan de Fuca plate and connected to a shore facility near Port Alberni on Vancouver Island. Five nodes were attached to the cable in the early in the summer of 2009 paving the way for junction boxes and scientific instruments installed in the late summer and fall. The NEPTUNE Canada Seismograph Network will consist initially of four broadband and four short period seismic systems. In the summer of 2009, three broadband OBS packages were deployed forming a large triangle with apexes at ODP 1027 in mid plate and two sites on the continental slope, ODP 889 and Barkley Canyon. In summer 2010 an additional broadband package will be installed on the Endeavour segment of the Juan de Fuca Ridge, and four short period instruments will be installed nearby forming a small array, 6 km in maximum dimension, to record earthquake activity in the vicinity of the many multidisciplinary ridge experiments. The broadband systems comprise a broadband seismometer and strong motion accelerometer in a surficially buried spherical titanium case, with a current meter, hydrophone and differential pressure gauge deployed nearby. The short period systems will include 3-component corehole seismometers on long term loan from the Monterey Bay Aquarium Research Institute (MBARI). All systems will have backup capacity for modest cable outages. The NEPTUNE Canada Seismograph Network relies heavily on knowledge gained from the previous seismographs temporarily deployed in the region by MBARI and the University of Washington and will re-occupy the broadband site and three short period sites at the ridge. NEPTUNE Canada seismic data will be archived by, and available from, both the Geological Survey of Canada and IRIS.

Overview of the Ocean Bottom Seismology Component of the Cascadia Initiative (Invited)

NASA Astrophysics Data System (ADS)

Toomey, D. R.; Allen, R. M.; Collins, J. A.; Dziak, R. P.; Hooft, E. E.; Livelybrooks, D.; McGuire, J. J.; Schwartz, S. Y.; Tolstoy, M.; Trehu, A. M.; Wilcock, W. S.

2013-12-01

We report on the experimental progress of the ocean bottom seismology component of the Cascadia Initiative (CI). The CI is an onshore/offshore seismic and geodetic experiment that takes advantage of an Amphibious Array Facility (AAF) to study questions ranging from megathrust earthquakes to volcanic arc structure to the formation, deformation and hydration of the Juan de Fuca and Gorda plates. This diverse set of objectives are all components of understanding the overall subduction zone system and require an array that provides high quality data that crosses the shoreline and encompasses relevant plate boundaries. In October 2010, an open community workshop was convened in Portland, Oregon that produced a series of recommendations to maximize the scientific return of the CI and to develop deployment plans for the offshore component of the experiment. The NSF Cascadia Initiative Workshop Report1 presents the scientific objectives of the CI, the resources involved and the community-defined ocean bottom seismometer (OBS) deployment plan. There are several noteworthy aspects of the CI: The CI is the first to utilize a new generation of OBSs that are designed to withstand trawling by fisheries, thus allowing the collection of seismic data in the shallow water that overlies much of the Cascadia megathrust. The CI is a plate-scale experiment that provides a unique opportunity to study the structure and dynamics of an entire oceanic plate, from its birth at a spreading center to its subduction beneath a continental plate. Together with the land stations that are part of the amphibious array and other land networks, the OBSs will provide coverage at a density comparable to the Transportable Array of Earthscope from the volcanic arc out to the Pacific-Juan de Fuca spreading center segments. The CI is a community experiment that provides open access to all data via the IRIS Data Management Center, thus ensuring that the scientific return from the investment of resources is maximized. Lastly, the CI includes a significant education and outreach component that is providing berths for students, post-docs and other scientists to participate in either deployment or recovery legs, thus providing the seismological community with opportunities to gain valuable experience in planning and carrying out an OBS experiment. The Cascadia Initiative Expedition Team (CIET) is a group of scientists who are leading the seagoing expeditions to deploy and recover OBSs and are developing related Education and Outreach modules. The CIET maintains a web site for the community where information regarding CI expeditions and OBS metadata are provided2. The CI is currently in its third year of data acquisition. The CIET presentation will report on the 2011-2013 field seasons, data quantity and quality, ongoing E&O efforts, and the schedule for OBS operations in 2014.

A Trial for Detecting the Temporal Variation in Seismic Velocity Accompanied by a Slow Slip Event using Seismic Interferometry of Ambient Noise

NASA Astrophysics Data System (ADS)

Uemura, Miyuu; Ito, Yoshihiro; Ohta, Kazuaki; Hino, Ryota; Shinohara, Masanao

2017-04-01

Seismic interferometry is one of the most effective techniques to detect temporal variations in seismic velocity before or after a large earthquake. Some previous studies have been reported on seismic velocity reduction due to the occurrence of large earthquakes (e.g., Wegler et al., 2009; Yamada et al., 2010) as well as preceding them (e.g., Lockner et al., 1977; Yoshimitsu et al., 2009). However, there have only been a few studies thus far which attempt to detect seismic velocity changes associated with slow slip events (SSEs). In this study, we focus on applying seismic interferometry to ambient noise data from ocean bottom seismometers (OBSs) deployed near a subduction zone. Between the end of January 2011 and the largest foreshock occurring on March 9th that precedes the March 11, 2011 Tohoku-Oki earthquake, SSEs and low-frequency tremors were detected offshore Miyagi Prefecture (Ito et al., 2013, 2015; Katakami et al., 2016). We applied our seismic interferometry analysis using ambient noise to recordings from 17 OBS stations that were installed in the vicinity of the 2011 Tohoku-Oki earthquake source region, and only considered the recordings from before that major earthquake. All the OBSs are short-period seismometers with three components which have an eigenfrequency of 4.5 Hz. These OBSs were deployed offshore Miyagi Prefecture between November 2010 and April 2011. Before proceeding with the seismic interferometry analysis, we needed to estimate the two horizontal components of the original deployment orientation for 13 OBSs in (we could not estimate them for 4 OBSs). To obtain the OBS orientation, we used particle orbits of some direct P waves from selected tectonic earthquakes, in order to extract one vertical and two horizontal components. Then, the seismic interferometry analysis consisted of the following steps. First, we applied a band-pass filter of 0.25-2.0 Hz and one-bit technique to the ambient noise signal. Second, we calculated auto-correlation functions (ACFs) for the radial and transverse components using a 5-s time window with lag time from -30 s to 30 s, sampled at intervals of 0.1 s. Using either seven or sixteen days of continuous waveform records or the entire time period, we can construct either a 7-day ACF, a 16-day ACF, or a reference ACF. Finally, we calculated the Correlation Coefficients (CCs) between the 7-day ACF or the 16-day ACF and the reference ACF. There are three important points in our results. First, during the occurrence of the SSE, the values of the CCs decrease. Second, the changes in the values of the CCs display regional differences across the OBS network. Third, the locations of the stations for which the drop of the CC from a value of 1.0 is large corresponds to the seafloor region above the rupture area of the largest foreshock, whereas the locations of the stations for which the drop from the CC of the previous period is large corresponds to the seafloor above the slip area of the SSEs detected before that foreshock.

Deep structure of the Algerian margin offshore Great Kabylie: Preliminary results of an offshore-onshore seismic profile (SPIRAL campaign)

NASA Astrophysics Data System (ADS)

Chafik, Aidi; Abd el Karim, Yelles; Marie-Odile, Beslier; Frauke, Klingelhoefer; Philippe, Schnurle; Rabah, Bracene; Hamou, Djellit; Audrey, Galve; Laure, Schenini; Françoise, Sage; Abdallah, Bounif Mohand ou; Philippe, Charvis

2013-04-01

In October-November 2009 the Algerian-French SPIRAL research program (Sismique Profonde et Investigation Régionale du Nord de l'ALgérie) was conducted onboard the R/V Atalante in order to understand the deep structure and tectonic history of the Algerian Margin using multichannel and wide-angle seismic data. An extensive dataset was acquired along five regional transects off Algeria, from Arzew Bay to the west, to Annaba to the east. The profiles range from 80 to 180 km long and around 40 ocean-bottom seismometers were deployed on each profile. All profiles were extended on land up to 125 km by land-stations to better constrain the structure of the margin and the nature of the ocean-continent transition zone. We present the preliminary results from modeling of deep and superficial structures in the central Algerian margin, more precisely in the region of the Great Kabylie where a N-S transect of combined wide-angle data using a set of 40 OBS (ocean bottom seismometer) and 24 on-land seismological stations and reflection seismic data was acquired. The profile with a total length of about 260 km (140 km offshore and approximately 124 km onshore), crosses from the north to south the Algeria-Provence Basin, the central Algerian Margin and onshore the geological unit of the Great Kabylie that represents the Kabylides block and the transitional zone between the internal zone (Kabylides) and the external zone in the central Algeria. The network (OBS and seismological stations), recorded 1031 low frequency air gun shots in order to ensure good penetration in the crust. Travel time tomography of first arrivals time of OBS data has yielded a preliminary model of P wave velocities along the profile. In the oceanic domain, a relatively thin crust of about 5 km thickness was imaged overlying a mantle characterized by seismic velocities of about 8 km/s, and covered by a thin sedimentary layer of about 2 km thickness. For the study of the sedimentary cover near the margin several MCS profiles were acquired in this region during the Spiral survey and previously by the Maradja cruise. This data sets allows to image reactivation of the Algerian Margin in this region.

Cascadia Initiative Ocean Bottom Seismograph Performance

NASA Astrophysics Data System (ADS)

Evers, B.; Aderhold, K.

2017-12-01

The Ocean Bottom Seismograph Instrument Pool (OBSIP) provided instrumentation and operations support for the Cascadia Initiative community experiment. This experiment investigated geophysical processes across the Cascadia subduction zone through a combination of onshore and offshore seismic data. The recovery of Year 4 instruments in September 2015 marked the conclusion of a multi-year experiment that utilized 60 ocean-bottom seismographs (OBSs) specifically designed for the subduction zone boundary, including shallow/deep water deployments and active fisheries. The new instruments featured trawl-resistant enclosures designed by Lamont-Doherty Earth Observatory (LDEO) and Scripps Institution of Oceanography (SIO) for shallow deployment [water depth ≤ 500 m], as well as new deep-water instruments designed by Woods Hole Oceanographic Institute (WHOI). Existing OBSIP instruments were also deployed along the Blanco Transform Fault and on the Gorda Plate through complementary experiments. Station instrumentation included weak and strong motion seismometers, differential pressure gauges (DPG) and absolute pressure gauges (APG). All data collected from the Cascadia, Blanco, and Gorda deployments is available through the Incorporated Research Institutions for Seismology (IRIS) Data Management Center (DMC). The Cascadia Initiative is the largest amphibious seismic experiment undertaken to date, encompassing a diverse technical implementation and demonstrating an effective structure for community experiments. Thus, the results from Cascadia serve as both a technical and operational resource for the development of future community experiments, such as might be contemplated as part of the SZ4D Initiative. To guide future efforts, we investigate and summarize the quality of the Cascadia OBS data using basic metrics such as instrument recovery and more advanced metrics such as noise characteristics through power spectral density analysis. We also use this broad and diverse deployment to explore other environmental and configuration factors that can impact sensor and network performance and inform the design of future deployments.

Brady's Geothermal Field Nodal Seismometers Metadata

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lesley Parker

Metadata for the nodal seismometer array deployed at the POROTOMO's Natural Laboratory in Brady Hot Spring, Nevada during the March 2016 testing. Metadata includes location and timing for each instrument as well as file lists of data to be uploaded in a separate submission.

Development, Manufacturing, and Preparation for Serial Production of Low Noise Seismometers Final Report CRADA No. TC02096.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vergino, E. S.; Passmore, P. R.

2012-01-23

This was a collaborative effort between Lawrence Livermore National Security, LLC as manager and operator of Lawrence Livermore National Laboratory (LLNL) and Refraction Technology, Inc. (REF TEK), to collaborate on the development of a broadband, competitive low-noise seismometer, rugged and easy to use for field deployments. The work involved collaborative work between LLNL, REF TEK and a group led by Federal State Unitary Enterprise, Research Institute of Pulse Technique (RIPT), Moscow, Russia. The proposed work focused on bringing an improved version of the Russian SDSE seismometer from development phase to production in two versions. The first was a very lowmore » cost, rugged, broadband seismometer for field deployment that would achieve noise levels comparable to the standard earth low noise model (LNM) of the USGS. All three components were integrated into one case, and have sensitivity near 2000 v/m/s, and analog output with bandwidth of .01 to 40 Hz with high coherence.« less

Ambient noise tomography of Lo'ihi

NASA Astrophysics Data System (ADS)

McClement, K.; Thurber, C. H.; Teel, A.; Caplan-Auerbach, J.

2012-12-01

Lo'ihi seamount, the youngest volcano in the Hawaiian-Emperor chain, lies approximately 30 km south of Hawai'i Island with its summit still approximately 1 km below sea level. Lo'ihi offers a unique opportunity to study the early formation of a hotspot volcano and can provide insight into the deep internal structure of the other volcanoes that make up the Hawaiian Islands. This study uses Ambient Noise Tomography (ANT) to create a 3D tomographic image of Lo'ihi's S-wave velocity structure from ocean bottom seismometer (OBS) data. ANT has been used in many subaerial studies but has seen very few applications to OBS data. This study uses continuous data recorded in 2010 to 2011 from 12 short-period OBS instruments deployed on and around Lo'ihi. With the farthest distance between stations being just over 30 km, the stations provide a fairly dense coverage mainly for the northern half of the volcano. Following the approach of Masterlark et al. [2010], we computed vertical-vertical and vertical-radial cross-correlations using 97 days of continuous data from the 12 stations to produce the ambient noise Green's functions. From these, dispersion curves were produced over a frequency range from .04 Hz to 0.65 Hz . After a quality control analysis, checkerboard tests were used to determine a suitable cell size for the 2D group velocity inversions. The final step is the inversion of the group velocity dispersion curves to create a 3D Vs model. The 3D Vs image produced through this method does not provide clear evidence of a shallow magma chamber; however, when compared to a previous P-wave velocity (Vp) model [Caplan-Auerbach, 2001], a high Vp/Vs ratio is evident especially at depths from 1 km to 5 km, indicating the presence of highly fractured rock.

The Presence and Characterization of Antarctic Bottom Water Located Between the Mid-Atlantic Ridge and the Rio Grande Rise

NASA Astrophysics Data System (ADS)

Miller, R. H.; Reece, R.; Estep, J.; Christeson, G. L.; Acquisto, T. M.

2016-12-01

Circumpolar waters of widely varying properties enter South Atlantic Ocean circulation, interleaving their properties. Antarctic bottom water (ABW) flows northward into the South Atlantic at the eastern edge of the South American continent and around the Rio Grande Rise (RGR), a large aseismic ocean ridge in the deep water off the coast of Brazil. The majority of ABW transport occurs below depths of 3500 m, so very little is lost at the top of the RGR. In early 2016, the CREST (Crustal Reflectivity Experiment Southern Transect) expedition acquired multichannel seismic (MCS) and ocean bottom seismometer (OBS) datasets along a crustal segment in the South Atlantic, stretching from the Mid Atlantic Ridge (MAR) west to the RGR. During OBS recovery, a communications problem occurred in which the OBS received the transducer pulse from the ship, but the ship did not receive the OBS return pulse. The nine shallowest instruments, closest to the MAR, did not experience this problem, but all remaining instruments did. All instruments were extensively tested in the water column and in the lab and exhibited no malfunctions. We hypothesize that a deepwater layer of differing physical properties, located nearer the OBS than the boat, dispersed the return pulse resulting in the break in communications. ABW is a good candidate for a potential cold deepwater body in this region. We will examine multi-beam bathymetry returns and seismic reflection data for indications of reflections in the deepwater column. If observations support the presence of cold deepwater, we will fully characterize its properties and boundaries and determine if the characteristics match that of ABW. This study will characterize the behavior and nature of potential cold deepwater currents east of the Rio Grande Rise in an attempt to verify the presence of ABW. Information regarding the effects of differential water layering on acoustic communication with seafloor instruments could benefit future deployments to affected regions. Additionally, more insight into deep water ocean circulation could provide critical information for modeling with implications for chemical and heat exchange as well as ocean-climate interaction.

OBSIP: An Evolving Facility for the Future of Geoscience

NASA Astrophysics Data System (ADS)

Evers, B.; Aderhold, K.

2015-12-01

The Ocean Bottom Seismograph Instrument Pool "OBSIP" is a National Science Foundation (NSF) sponsored instrument facility that provides ocean bottom seismometers and technical support for research in the areas of marine geology, seismology, and geodynamics. OBSIP provides both short period instruments (for active source seismic refraction studies) and long period instruments (for long term passive experiments). OBSIP is comprised of three Institutional Instrument Contributors each of whom contribute instruments and technical support to the pool and an OBSIP Management Office. In 2015, OBSIP will provide instruments for six experiments and support nine research cruises recovering and/or deploying instruments. This includes the final recoveries for the Cascadia Initiative experiment and the Eastern North American Margin experiment, both multi-year community seismic experiments integrating large onshore and offshore deployments of instruments from multiple IICs. OBSIp supported additional experiments in New Zealand and Malawi, Africa. An active source experiment to image the magma plumbing of Santorini employs OBSIP's entire short period sensor pool. OBSIP is also incorporating new technical developments in the OBSIP fleet including long duration OBS technology, new shielding designs, and sensor upgrades. OBSIP continues to enable innovation in experiment design, instrument capabilities, and data return/QAQC tracking and adapts to the needs of a rapidly increasing and diversifying pool of users.

The MESUR Mission

NASA Technical Reports Server (NTRS)

Squyres, S. W.

1993-01-01

The MESUR mission will place a network of small, robust landers on the Martian surface, making a coordinated set of observations for at least one Martian year. MESUR presents some major challenges for development of instruments, instrument deployment systems, and on board data processing techniques. The instrument payload has not yet been selected, but the straw man payload is (1) a three-axis seismometer; (2) a meteorology package that senses pressure, temperature, wind speed and direction, humidity, and sky brightness; (3) an alphaproton-X-ray spectrometer (APXS); (4) a thermal analysis/evolved gas analysis (TA/EGA) instrument; (5) a descent imager, (6) a panoramic surface imager; (7) an atmospheric structure instrument (ASI) that senses pressure, temperature, and acceleration during descent to the surface; and (8) radio science. Because of the large number of landers to be sent (about 16), all these instruments must be very lightweight. All but the descent imager and the ASI must survive landing loads that may approach 100 g. The meteorology package, seismometer, and surface imager must be able to survive on the surface for at least one Martian year. The seismometer requires deployment off the lander body. The panoramic imager and some components of the meteorology package require deployment above the lander body. The APXS must be placed directly against one or more rocks near the lander, prompting consideration of a micro rover for deployment of this instrument. The TA/EGA requires a system to acquire, contain, and heat a soil sample. Both the imagers and, especially, the seismometer will be capable of producing large volumes of data, and will require use of sophisticated data compression techniques.

Aftershock source properties of events following the 2013 Craig Earthquake: new evidence for structural heterogeneity on the northern Queen Charlotte Fault

NASA Astrophysics Data System (ADS)

Roland, E. C.; Walton, M. A. L.; Ruppert, N. A.; Gulick, S. P. S.; Christeson, G. L.; Haeussler, P. J.

2014-12-01

In January 2013, a Mw 7.5 earthquake ruptured a segment of the Queen Charlotte Fault offshore the town of Craig in southeast Alaska. The region of the fault that slipped during the Craig earthquake is adjacent to and possibly overlapping with the northern extent of the 1949 M 8.1 Queen Charlotte earthquake rupture (Canada's largest recorded earthquake), and is just south of the rupture area of the 1972 M 7.6 earthquake near Sitka, Alaska. Here we present aftershock locations and focal mechanisms for events that occurred four months following the mainshock using data recorded on an Ocean Bottom Seismometer (OBS) array that was deployed offshore of Prince of Wales Island. This array consisted of 9 short period instruments surrounding the fault segment, and recorded hundreds of aftershocks during the months of April and May, 2013. In addition to highlighting the primary mainshock rupture plane, aftershocks also appear to be occurring along secondary fault structures adjacent to the main fault trace, illuminating complicated structure, particularly toward the northern extent of the Craig rupture. Focal mechanisms for the larger events recorded during the OBS deployment show both near-vertical strike slip motion consistent with the mainshock mechanism, as well as events with varying strike and a component of normal faulting. Although fault structure along this northern segment of the QCF appears to be considerably simpler than to the south, where a higher degree of oblique convergence leads to sub-parallel compressional deformation structures, secondary faulting structures apparent in legacy seismic reflection data near the Craig rupture may be consistent with the observed seismicity patterns. In combination, these data may help to characterize structural heterogeneity along the northern segment of the Queen Charlotte Fault that contributes to rupture segmentation during large strike slip events.

Cruise report for P1-13-LA, U.S. Geological Survey gas hydrates research cruise, R/V Pelican April 18 to May 3, 2013, deepwater Gulf of Mexico

USGS Publications Warehouse

Haines, Seth S.; Hart, Patrick E.; Ruppel, Carolyn; O'Brien, Thomas; Baldwin, Wayne; White, Jenny; Moore, Eric; Dal Ferro, Peter; Lemmond, Peter

2014-01-01

The U.S. Geological Survey led a seismic acquisition cruise in the Gulf of Mexico from April 18 to May 3, 2013, with the objectives of (1) achieving improved imaging and characterization at two established gas hydrate study sites, and (2) refining geophysical methods for gas hydrate characterization in other locations. We conducted this acquisition aboard the R/V Pelican, and used a pair of 105/105-cubic-inch generator/injector air guns to provide seismic energy that we recorded using a 450-meter 72-channel digital hydrophone streamer and 25 multicomponent ocean-bottom seismometers. In the area of lease block Green Canyon 955, we deployed 21 ocean-bottom seismometers and acquired approximately 400 kilometers of high-resolution two-dimensional streamer seismic data in a grid with line spacing as small as 50 meters and along radial lines that provide source offsets up to 10 kilometers and diverse azimuths for the ocean-bottom seismometers. In the area of lease block Walker Ridge 313, we deployed 25 ocean-bottom seismometers and acquired approximately 450 kilometers of streamer seismic data in a grid pattern with line spacing as small as 250 meters and along radial lines that provide source offsets up to 10 kilometers for the ocean-bottom seismometers. The data acquisition effort was conducted safely and met the scientific objectives.

Brady's Geothermal Field Nodal Seismometer Earthquake Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurt Feigl

90-second records of data from 238 three-component nodal seismometer deployed at Bradys geothermal field. The time window catches an earthquake arrival. Earthquake data from USGS online catalog: Magnitude: 4.3 ml +/- 0.4 Location: 38.479 deg N 118.366 deg W +/- 0.7 km Depth: 9.9 km +/- 0.7 Date and Time: 2016-03-21 07:37:10.535 UTC

Trillium 360 Seismometer Initial Test Results

NASA Astrophysics Data System (ADS)

Bainbridge, Geoffrey; Devanney, Peter; Upadhyaya, Sarvesh

2017-04-01

Test results for Trillium 360 show this seismometer can resolve the Peterson New Low Noise Model down to 300 seconds period. This has been confirmed at multiple sites: Pinon Flat (California), Albuquerque Seismological Laboratory (New Mexico) and Nanometrics (Ottawa, Canada). The Pinon Flat deployment captured the March 2, 2016 Mw=7.9 Indonesian event and showed a response coherent with reference sensors including an STS-1 at periods down to 0.0015 Hz. At frequencies below 0.0015 Hz the reference sensors showed a noncoherent spurious response, i.e. noise in the presence of signal, whereas the Trillium 360 was relatively unaffected. Magnetic sensitivity has been measured to be 0.01 m/s^2/T in two independent tests at ASL and Nanometrics. Temperature sensitivity is 3*10^-4 m/s^2/T. This combination of low sensitivity to both magnetic field and temperature is achieved through magnetic shielding which resolves the side effect of magnetic sensitivity in temperature-compensated ferromagnetic spring alloys. The T360 seismometer components are sufficiently miniaturized for deployment in a borehole. This enables low-noise performance even in an urban environment with thick sediments (at Nanometrics, Ottawa) since the seismometer can be emplaced in bedrock below surface sediments and away from surface noise.

Amphibian Seismological Studies in the Ross Sea, Antarctica

NASA Astrophysics Data System (ADS)

Schmidt-Aursch, Mechita; Kuk Hong, Jong; Lee, Won Sang; Geissler, Wolfram; Yun, Sukyoung; Gohl, Karsten; Park, Yongcheol; Yoo, Hyun Jae

2016-04-01

The Antarctic Ross Sea is one of the key regions for polar research activities. Research stations from several countries located at the coast are the base for inland expeditions. Even in the austral summer, the Ross Sea is party covered with drifting ice fields; this requires an icebreaker for all marine explorations. Therefore, large geophysical surveys in the Ross Sea are difficult. But the area is of special interest for seismologists: The Terror Rift in the western Ross Sea is a prominent neotectonic structure of the West Antarctic Rift System (WARS). It is located near the coast in the Victoria Land Basin and extends parallel to the Transantarctic Mountains. The rifting processes and the accompanying active onshore volcanism lead to increased seismicity in the region. The annual waxing and waning of the sea-ice and the dynamics of the large Ross Ice Shelf and nearby glaciers generate additional seismic signals. Investigation on seismological activities associated with the WARS and the cryogenic signals simultaneously would give us an unprecedented opportunity to have a better understanding of the Evolution of the WARS (EWARS) and the rapid change in the cryospheric environment nearby. The Korea Polar Research Institute (KOPRI) and the Alfred-Wegener-Institut (AWI) have conducted a pilot study off the Korean Jang Bogo research station in the Terra Nova Bay by developing a collaborative research program (EWARS) since 2011 to explore seismicity and seismic noise in this region. Four broadband ocean-bottom seismometers (OBS) from the German DEPAS pool were deployed in January 2012 with the Korean research icebreaker RV Araon. Three instruments could successfully be recovered after 13 months, the fourth OBS was not accessible due to local sea-ice coverage. We have successfully completed a second recovery operation in January 2014. All stations recorded data of good quality, one station stopped after 8 months due to a recorder error. The OBS recovered in 2014 recorded more than 17 months of data until the batteries were discharged. In this contribution, we present data and first results including temporal variation of seismic ambient noise, receiver functions, local seismicity, and noise correlation functions through examining the OBS data incorporating with the onshore seismic observation data.

Constraining Earthquake Source Parameters in Rupture Patches and Rupture Barriers on Gofar Transform Fault, East Pacific Rise from Ocean Bottom Seismic Data

NASA Astrophysics Data System (ADS)

Moyer, P. A.; Boettcher, M. S.; McGuire, J. J.; Collins, J. A.

2015-12-01

On Gofar transform fault on the East Pacific Rise (EPR), Mw ~6.0 earthquakes occur every ~5 years and repeatedly rupture the same asperity (rupture patch), while the intervening fault segments (rupture barriers to the largest events) only produce small earthquakes. In 2008, an ocean bottom seismometer (OBS) deployment successfully captured the end of a seismic cycle, including an extensive foreshock sequence localized within a 10 km rupture barrier, the Mw 6.0 mainshock and its aftershocks that occurred in a ~10 km rupture patch, and an earthquake swarm located in a second rupture barrier. Here we investigate whether the inferred variations in frictional behavior along strike affect the rupture processes of 3.0 < M < 4.5 earthquakes by determining source parameters for 100 earthquakes recorded during the OBS deployment.Using waveforms with a 50 Hz sample rate from OBS accelerometers, we calculate stress drop using an omega-squared source model, where the weighted average corner frequency is derived from an empirical Green's function (EGF) method. We obtain seismic moment by fitting the omega-squared source model to the low frequency amplitude of individual spectra and account for attenuation using Q obtained from a velocity model through the foreshock zone. To ensure well-constrained corner frequencies, we require that the Brune [1970] model provides a statistically better fit to each spectral ratio than a linear model and that the variance is low between the data and model. To further ensure that the fit to the corner frequency is not influenced by resonance of the OBSs, we require a low variance close to the modeled corner frequency. Error bars on corner frequency were obtained through a grid search method where variance is within 10% of the best-fit value. Without imposing restrictive selection criteria, slight variations in corner frequencies from rupture patches and rupture barriers are not discernable. Using well-constrained source parameters, we find an average stress drop of 5.7 MPa in the aftershock zone compared to values of 2.4 and 2.9 MPa in the foreshock and swarm zones respectively. The higher stress drops in the rupture patch compared to the rupture barriers reflect systematic differences in along strike fault zone properties on Gofar transform fault.

New seismic instrumentation packaged for all terrestrial environments (including the quietest observatories!).

NASA Astrophysics Data System (ADS)

Parker, Tim; Devanney, Peter; Bainbridge, Geoff; Townsend, Bruce

2017-04-01

The march to make every type of seismometer, weak to strong motion, reliable and economically deployable in any terrestrial environment continues with the availability of three new sensors and seismic systems including ones with over 200dB of dynamic range. Until recently there were probably 100 pier type broadband sensors for every observatory type pier, not the types of deployments geoscientists are needing to advance science and monitoring capability. Deeper boreholes are now the recognized quieter environments for best observatory class instruments and these same instruments can now be deployed in direct burial environments which is unprecedented. The experiences of facilities in large deployments of broadband seismometers in continental scale rolling arrays proves the utility of packaging new sensors in corrosion resistant casings and designing in the robustness needed to work reliably in temporary deployments. Integrating digitizers and other sensors decreases deployment complexity, decreases acquisition and deployment costs, increases reliability and utility. We'll discuss the informed evolution of broadband pier instruments into the modern integrated field tools that enable economic densification of monitoring arrays along with supporting new ways to approach geoscience research in a field environment.

Inversion of ocean-bottom seismometer (OBS) waveforms for oceanic crust structure: a synthetic study

NASA Astrophysics Data System (ADS)

Li, Xueyan; Wang, Yanbin; Chen, Yongshun John

2016-08-01

The waveform inversion method is applied—using synthetic ocean-bottom seismometer (OBS) data—to study oceanic crust structure. A niching genetic algorithm (NGA) is used to implement the inversion for the thickness and P-wave velocity of each layer, and to update the model by minimizing the objective function, which consists of the misfit and cross-correlation of observed and synthetic waveforms. The influence of specific NGA method parameters is discussed, and suitable values are presented. The NGA method works well for various observation systems, such as those with irregular and sparse distribution of receivers as well as single receiver systems. A strategy is proposed to accelerate the convergence rate by a factor of five with no increase in computational complexity; this is achieved using a first inversion with several generations to impose a restriction on the preset range of each parameter and then conducting a second inversion with the new range. Despite the successes of this method, its usage is limited. A shallow water layer is not favored because the direct wave in water will suppress the useful reflection signals from the crust. A more precise calculation of the air-gun source signal should be considered in order to better simulate waveforms generated in realistic situations; further studies are required to investigate this issue.

A Laser Interferometric Miniature Seismometer

DTIC Science & Technology

2010-09-01

A LASER INTERFEROMETRIC MINIATURE SEISMOMETER Dustin W. Carr, Patrick C. Baldwin, Shawn A. Knapp-Kleinsorge, Howard Milburn, and David Robinson...Symphony Acoustics, Inc. Sponsored by the National Nuclear Security Administration Award No. DE-FG02-08ER85108.001 ABSTRACT The threat of...performance, compact device can enable rapid deployment of large-scale arrays , which can in turn be used to provide higher-quality data during times of

The SEIS Experiment for the InSight mission: status and performance expectations

NASA Astrophysics Data System (ADS)

Mimoun, David; Lognonne, Philippe; Banerdt, W. Bruce; Laudet, Philippe; De Raucourt, Sébastien; IJpelaan, Frans; Kerjean, Laurent; Perez, Rene; Pont, Gabriel; Sylvestre-Baron, Annick; verdier, Nicolas; Denise, Robert; Feldman, Jason; Hurst, Ken; Klein, Kerry; Giardini, Domenico; Zweifel, Peter; Pike, W. Tom; Calcutt, Simon; Bramanti, Christina

2015-04-01

The Insight NASA Discovery mission, led by the Jet Propulsion Laboratory, will deploy in September 2016 a very broadband seismometer on the Mars surface, SEIS (Seismic Experiment for Interior Structure). It is a hybrid 3-axes instrument, which encloses 3 very broadband oblique sensors and 3 short period sensors. The sensor assembly and its wind and thermal shield will by deployed on the Mars surface from the Phoenix-like spacecraft by a robotic arm (IDS). The acquisition system will be hosted in the spacecraft warm electronics box, and connected to the deployed sensor assembly by a tether. The SEIS experiment is provided by CNES, the French Space Agency that makes the coordination of a wide consortium including IPGP of Paris (SEIS PI Institution), Imperial College of London, Oxford University, MPS of Göttingen, ETH of Zürich, ISAE from Toulouse and the Jet Propulsion Laboratory of Pasadena. In addition to the seismometer, the Insight payload will also include a suite of instruments complementary to the seismometer, such as a precision temperature sensor, a micro-barometer, a magnetometer and a wind sensor, making it the first geophysical multi-parameter station on another planet. A heat flow sensor and geodetic measurements will provide additional science measurements, in order to constrain the internal structure of Mars. Several challenges have been overcome to design and realize the planetary seismometer, which will exhibit a noise of about 10-9 m/s2/sqrt(Hz) in its seismic bandwidth bandwidth (0.01-1 Hz) for the very broadband component. These challenges include a very efficient insulation from the external temperature variations, and a finely crafted mechanical design to keep the extreme sensitivity of the seismometer, while allowing enough robustness for the harsh mechanical environment encountered during the launch and landing sequences. Also, specific attention has been paid to understanding the various environment contributions to the noise figure. A discussion will be presented, on how to understand the seismometer performance figure in a changing environment, and how to secure the mission science goals in the challenging environment of the Mars surface.

Vp/Vs Ratio of Juan de Fuca Plate Sediments Along the Cascadia Deformation Front From Analysis of Controlled-Source Multi-Component OBS Records

NASA Astrophysics Data System (ADS)

Zhu, J.; Canales, J. P.; Han, S.; Carbotte, S. M.; Arnulf, A. F.; Nedimovic, M. R.

2017-12-01

The seismic characteristics (Vp, Vs, Vp/Vs, anisotropy) and derived physical properties (porosity, effective stress, pore fluid pressure, and crack density/orientation) of sediments entering a subduction zone are key parameters to understand subduction plate interface properties and seismogenic behavior. Here we present preliminary results of the average Vp/Vs within the 2-3-km-thick sediment section along the Cascadia deformation front between 44°-48°N offshore Oregon and Washington. We use data acquired in 2012 during the Juan de Fuca Ridge to Trench (R2T) controlled-source seismic experiment. We use P-waves and PPS converted-wave modes (i.e., P-to-S conversions of up-going waves at the crust-sediment interface) observed in 25 multi-component, short-period ocean bottom seismometers (OBS) deployed along an 400-km-long profile located 10-15 km seaward from the trench. The Vp/Vs was calculated following the method of Tsuji et al. (2011), which uses the seafloor-to-basement two-way traveltime determined from a coincident multichannel seismic reflection profile, and the time lag DT between the crustal P-refracted and PPS-converted waves. Processing of the OBS data included rotation into radial and traverse components, bandpass filtering, and predictive deconvolution. Our preliminary results show that the average sediment Vp/Vs along the profile varies from 2.8 to 3.35. Along the central-northern Oregon margin, Vp/Vs ranges between 2.8 and 2.95, while along the northern Washington margin Vp/Vs are slightly higher (2.95-3.05). We find the largest Vp/Vs values (≥3.1) offshore southern WA (between 46°-46.7°N). These preliminary results imply along-margin variations in subducting sediments along Cascadia. Implications for the physical properties of the sediments entering Cascadia are currently being explored and will be presented at the meeting.

Shear wave modelling of high resolution OBS data in a gas hydrate environment in the Danube deep-sea fan, Black Sea

NASA Astrophysics Data System (ADS)

Dannowski, A.; Bialas, J.; Zander, T.; Klaeschen, D.

2016-12-01

The Danube deep-sea fan, with his ancient channel-levee systems, hosts multiple bottom-simulating reflections (BSRs) observed in high-resolution reflection seismic data, indicating the occurrence of gas hydrates and free gas. To image the distribution of submarine gas hydrates and the occurrence of free gas in a channel-levee system, high-resolution 2D and 3D multichannel seismic reflection data were collected and fifteen ocean bottom seismometers (OBS) were deployed. The OBS data in particular reveal information about seismic P- and S-wave velocities of the subsurface. They record wave fields of a wide range of incidence angles. Both, P- and S-wave traveltime modelling cover a depth down to 1.5 km below the seafloor; thus, providing seismic velocity information far below the BSR. The seismic P-wave velocities increase with depth from 1600 m/s beneath the seafloor up to 2400 m/s at 1.5 km depth. The frequencies of the S-waves are much lower than the P-wave reflection signals. This is characteristic for shear waves in unconsolidated sediments where the S-wave attenuation is high. However, they travel much slower than P-waves and thus, show a higher resolution. The first S-wave appears at 0.7 s after the direct wave. Some of the S-phases can be traced up to 3.5 km in offset to the station. The seismic S-wave velocities increase from 240 m/s beneath the seafloor up to 1100 m/s at a depth of 1.5 km below the seafloor. From these observations, the P-to-S ratio can be derived. The P-to-S ratio might help to estimate the thickness of the zones with gas hydrates and free gas, while there will be a limited capability to constrain their concentrations.

Deployment of the Oklahoma borehole seismic experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harben, P.E.; Rock, D.W.

1989-01-20

This paper discusses the Oklahoma borehole seismic experiment, currently in operation, set up by members of the Lawrence Livermore National Laboratory Treaty Verification Program and the Oklahoma Geophysical Observatory to determine deep-borehole seismic characteristics in geology typical of large regions in the Soviet Union. We evaluated and logged an existing 772-m deep borehole on the Observatory site by running caliper, cement bonding, casing inspection, and hole-deviation logs. Two Teledyne Geotech borehole-clamping seismometers were placed at various depths and spacings in the deep borehole. Currently, they are deployed at 727 and 730 m. A Teledyne Geotech shallow-borehole seismometer was mounted inmore » a 4.5-m hole, one meter from the deep borehole. The seismometers' system coherency were tested and found to be excellent to 35 Hz. We have recorded seismic noise, quarry blasts, regional earthquakes and teleseisms in the present configuration. We will begin a study of seismic noise and attenuation as a function of depth in the near future. 7 refs., 18 figs.« less

Characteristics of Offshore Hawai';i Island Seismicity and Velocity Structure, including Lo';ihi Submarine Volcano

NASA Astrophysics Data System (ADS)

Merz, D. K.; Caplan-Auerbach, J.; Thurber, C. H.

2013-12-01

The Island of Hawai';i is home to the most active volcanoes in the Hawaiian Islands. The island's isolated nature, combined with the lack of permanent offshore seismometers, creates difficulties in recording small magnitude earthquakes with accuracy. This background offshore seismicity is crucial in understanding the structure of the lithosphere around the island chain, the stresses on the lithosphere generated by the weight of the islands, and how the volcanoes interact with each other offshore. This study uses the data collected from a 9-month deployment of a temporary ocean bottom seismometer (OBS) network fully surrounding Lo';ihi volcano. This allowed us to widen the aperture of earthquake detection around the Big Island, lower the magnitude detection threshold, and better constrain the hypocentral depths of offshore seismicity that occurs between the OBS network and the Hawaii Volcano Observatory's land based network. Although this study occurred during a time of volcanic quiescence for Lo';ihi, it establishes a basis for background seismicity of the volcano. More than 480 earthquakes were located using the OBS network, incorporating data from the HVO network where possible. Here we present relocated hypocenters using the double-difference earthquake location algorithm HypoDD (Waldhauser & Ellsworth, 2000), as well as tomographic images for a 30 km square area around the summit of Lo';ihi. Illuminated by using the double-difference earthquake location algorithm HypoDD (Waldhauser & Ellsworth, 2000), offshore seismicity during this study is punctuated by events locating in the mantle fault zone 30-50km deep. These events reflect rupture on preexisting faults in the lower lithosphere caused by stresses induced by volcano loading and flexure of the Pacific Plate (Wolfe et al., 2004; Pritchard et al., 2007). Tomography was performed using the double-difference seismic tomography method TomoDD (Zhang & Thurber, 2003) and showed overall velocities to be slower than the regional velocity model (HG50; Klein, 1989) in the shallow lithosphere above 16 km depth. This is likely a result of thick deposits of volcaniclastic sediments and fractured pillow basalts that blanket the southern submarine flank of Mauna Loa, upon which Lo';ihi is currently superimposing (Morgan et al., 2003). A broad, low-velocity anomaly was observed from 20-40 km deep beneath the area of Pahala, and is indicative of the central plume conduit that supplies magma to the active volcanoes. A localized high-velocity body is observed 4-6 km deep beneath Lo';ihi's summit, extending 10 km to the North and South. Oriented approximately parallel to Lo';ihi's active rift zones, this high-velocity body is suggestive of intrusion in the upper crust, similar to Kilauea's high-velocity rift zones.

Broadband Seismometer at 2500m Depth in the Mediterranean Sea

NASA Astrophysics Data System (ADS)

Deschamps, A.; Hello, Y.; Charvis, P.; Dugué, M.; Bertin, V.; Valdy, P.; Le van Suu, A.; Real, D.

2003-04-01

In the frame of the ANTARES project, devoted to solar neutrinos detection across a large (0.1 km3) water volume located in deep sea, sea bottom facilities were developed at a depth of 2500m. Power supply, instrumentation control and data transmission have been implemented offshore Toulon (France) through a 43km long marine cable. A broadband seismological sensor has been installed among the instrumentation to control of physical and chemical environment of the neutrino detectors. The instrument was designed by Guralp Systems on the basis of CMG-3T seismometer (band-pass 120s-50hz) connected to a CMG DM24 digitizer for mechanical control and signal digitisation. Seismometer was inserted in titanium housing which fulfil the safety requirements of deployment operation. Control of CMG DM24 through asynchronous RS232 serial line was implemented in the ANTARES acquisition software running on the sea bottom. An interface running at the surface allows control and storage of the data. In January, the sensor was launched with the ANTARES instrumental line. In a second step the sensor has been slightly moved away from the ANTARES structure (60m), partly buried in the ground, roughly levelled and oriented by the IFREMER submarine Nautile. During the same operation the instrumentation line was connected to the power supply and data acquisition control. Masses of the seismometer were unlocked from the surface. Data are now continuously collected from Toulon and transmitted to Geosciences Azur in quasi real time. After a test period of 3 months, the sensor should be recovered for upgrades. For the final deployment (10 years), the ANTARES time control signal should be used to synchronise the sensor internal clock. This is the first real time broadband seismometer deployed in Europe and it will increase, in the future, our capability of marine earthquake detection in the area.

A 80 OBS and 30 Land 3-component seismometers array encompassing the 280 km segment of the Lesser Antilles subduction megathrust seismogenic zone: view of current seismicity

NASA Astrophysics Data System (ADS)

Laigle, Mireille; Sapin, Martine; Ruiz, Mario; Diaz, Jordi; Kissling, Edi; Charvis, Philippe; Flueh, Ernst; Hirn, Alfred

2010-05-01

An extensive onshore and offshore seismic station array in the Lesser Antilles subduction zone allows to monitor microearthquake activity for a period of 4 months in a region previously outside of reach for detailed observation. Such a network has been possible thanks to a cluster of 3 seismic surveys (TRAIL - F/S Merian, SISMANTILLESII - N/O Atalante, and OBSANTILLES - N/O Antea) for deploying and recovering the instruments from several pools (Geoazur, INSU-IPGP, IFM-GEOMAR, AWI ). It has been followed by an additional deployment of the 28 GeoAzur OBSs (OBSANTILLES - N/O Antea) during 5 months in the south-western half. These operations have been carried out for the seismic investigation of the Antilles megathrust seismogenic zone in the framework of the THALES WAS RIGHT european project, and with also the financial support of the french ANR Catastrophes Telluriques et Tsunamis (SUBSISMANTI) and by the EU SALVADOR Programme of IFM-GEOMAR. Onshore, 30 3-components land stations (CSIC Barcelone, IPG Paris, INSU-RLBM and -LITHOSCOPE) have been temporarily deployed. The deep seismic structure of the whole area has been investigated during these seismic surveys by wide-angle reflection and refraction seismics recorded by these instruments as well as multi-channel reflection seismic imaging (MCS) along a dense grid of crossing profiles at the OBS positions providing excellent velocity information for the upper plate. Both the location and the interpretation of the recorded earthquake activity require constraints on the deep seismic structure, which will be discussed with respect to the 3D geometry of the interplate boundary and oceanic Moho, as well as those of the forearc basement and Moho. Preliminary locations have been obtained within a simple 1D velocity model by taking into account corrections for the variable thickness of the mud- and sediments layers beneath each OBS. The latter are estimated for both P- and S-waves to compensate for the huge structural heterogeneity on the arrival times and their effects will be discussed in map and along vertical cross-sections aligned with the seismic profiles. A first order result is that the previously unsampled seaward region remains aseismic through the whole period of observation. Another main result, at least in a model not yet accounting for deep structural heterogeneity, is that the seismicity is principally located deeper than the contact between the forearc crust and the subducting oceanic crust as derived from the refraction-reflection approaches in the general project, and in both plates. Data are being prepared for a joint inversion of earthquake locations, shot first arrival times and 3D heterogeneity.

Multichannel seismic-reflection profiling on the R/V Maurice Ewing during the Los Angeles Region Seismic Experiment (LARSE), California

USGS Publications Warehouse

Brocher, Thomas M.; Clayton, Robert W.; Klitgord, Kim D.; Bohannon, Robert G.; Sliter, Ray; McRaney, John K.; Gardner, James V.; Keene, J.B.

1995-01-01

This report describes the acquisition of deep-crustal multichannel seismic-reflection data in the Inner California Borderland aboard the R/V Maurice Ewing, conducted in October 1994 as part of the Los Angeles Regional Seismic Experiment (LARSE). LARSE is a cooperative study of the crustal structure of southern California involving earth scientists from the U.S. Geological Survey, Caltech, the University of Southern California, the University of California Los Angeles, and the Southern California Earthquake Center (SCEC). During LARSE, the R/V Ewing's 20- element air gun array, totaling 137.7 liters (8470 cu. in.), was used as the primary seismic source for wide-angle recording along three main onshore-offshore lines centered on the Los Angeles basin and the epicenters of the 1933 Long Beach and 1994 Northridge earthquakes. The LARSE onshore-offshore lines were each 200-250 km long, with the offshore portions being between 90 and 150 km long. The nearly 24,000 air gun signals generated by the Ewing were recorded by an array of 170 PASSCAL REFTEK recorders deployed at 2 km intervals along all three of the onshore lines and 9 ocean bottom seismometers (OBSs) deployed along two of the lines. Separate passes over the OBS-deployment lines were performed with a long air gun repetition rate (60 and 90 seconds) to minimize acoustic-wave interference from previous shots in the OBS data. The Ewing's 4.2-km, 160-channel, digital streamer was also used to record approximately 1250 km of 40-fold multichannel seismic-reflection data. To enhance the fold of the wide-angle data recorded onshore, mitigating against cultural and wind noise in the Los Angeles basin, the entire ship track was repeated at least once resulting in fewer than about 660 km of unique trackline coverage in the Inner Borderland. Portions of the seismic-reflection lines were repeated up to 6 times. A variety of other geophysical data were also continuously recorded, including 3.5 kHz bathymetry, multi-beam swath Hydrosweep bathymetry, magnetics, and gravity data. In this report, we describe the equipment and procedures used to acquire multichannel seismic-reflection and other geophysical data aboard the Ewing, provide a detailed cruise narrative, discuss the reduction of the data, and present near-trace constant offset seismic sections of the acquired profiles.

Brady's Geothermal Field Nodal Seismometer Active Source Data Sample

DOE Data Explorer

Kurt Feigl

2016-03-25

This data is in sac format and includes recordings of two active source events from 238 three-component nodal seismometers deployed at Bradys Hot Springs geothermal field as part of the PoroTomo project. The source was a viberoseis truck operating in P-wave vibrational mode and generating a swept-frequency signal. The files are 33 seconds long starting 4 seconds before each sweep was initiated. There is some overlap in the file times.

Sensor Emplacement Techniques and Seismic Noise Analysis for USArray Transportable Array Seismic Stations

NASA Astrophysics Data System (ADS)

Busby, Robert; Frassetto, Andy; Hafner, Katrin; Woodward, Robert; Sauter, Allan

2013-04-01

In preparation for deployment of EarthScope's USArray Transportable Array (TA) in Alaska beginning in 2014, the National Science Foundation (NSF) is supporting exploratory work on seismic station design, sensor emplacement and communication concepts appropriate for the challenging high-latitude environment that is proposed for deployment. IRIS has installed several experimental stations to evaluate different sensor emplacement schemes both in Alaska and the lower-48 U.S. The goal of these tests is to maintain or enhance a station's noise performance while minimizing its footprint and the equipment, materials, and overall expense required for its construction. Motivating this approach are recent developments in posthole broadband seismometer design and the unique conditions for operating in Alaska, where there are few roads, cellular communications are scarce, most areas are only accessible by small plane or helicopter, and permafrost underlies much of the northern tundra. In this study we review our methods used for directly emplacing of broadband seismometers in comparison to the current methods used to deploy TA stations. These primarily focus on using an auger to drill three to five meters, beneath the active layer of the permafrost, or coring directly into surface bedrock to one meter depth using a portable drill. Both methods have proven logistically effective in trials. Subsequent station performance can be quantitatively assessed using probability density functions summed from power spectral density estimates. These are calculated for the continuous time series of seismic data recorded for each channel of the seismometer. There are five test stations currently operating in Alaska. One was deployed in August 2011 and the remaining four in October 2012. Our results show that the performance of seismometers in Alaska with auger-hole or core-hole installations equals or exceeds that of the quietest TA stations in the lower-48, particularly at long periods, and in exceptional cases approaches the performance of the GSN low noise model. The station at Poker Flat Research Range, Alaska co-locates a sensor in a 5 meter deep auger hole with a 2 meter deep TA tank installation typical of the lower-48. The augered seismometer is currently over 20 dB quieter at periods over 40 seconds than the TA tank installation. Similar performance has been observed at other TA stations, which also compare favorably to co-located permanent stations.

Cruise report for a seismic investigation of gas hydrates in the Mississippi Canyon region, northern Gulf of Mexico; cruise M1-98-GM

USGS Publications Warehouse

Cooper, Alan K.; Hart, Patrick E.; Pecher, Ingo

1998-01-01

During the cruise about 850 km of multichannel and single-channel seismic data were recorded. Seismic measurements at nine ocean-bottom seismometer (OBS) stations were recorded for several of the multichannel tracklines (see Fig. 3 in report). The following report describes the field operations and equipment systems employed, gives two examples of ship-board seismic records, and outlines a few preliminary results.

Observation and Simulation of Microseisms Offshore Ireland

NASA Astrophysics Data System (ADS)

Le Pape, Florian; Bean, Chris; Craig, David; Jousset, Philippe; Donne, Sarah; Möllhoff, Martin

2017-04-01

Although more and more used in seismic imagery, ocean induced ambient seismic noise is still not so well understood, particularly how the signal propagates from ocean to land. Between January and September 2016, 10 broadband Ocean Bottom Seismometers (OBSs) stations, including acoustic sensors (hydrophone), were deployed across the shelf offshore Donegal and out into the Rockall Trough. The preliminary results show spatial and temporal variability in the ocean generated seismic noise which holds information about changes in the generation source process, including meteorological information, but also in the geological structure. In addition to the collected OBS data, numerical simulations of acoustic/seismic wave propagation are also considered in order to study the spatio-temporal variation of the broadband acoustic wavefield and its connection with the measured seismic wavefield in the region. Combination of observations and simulations appears significant to better understand what control the acoustic/seismic coupling at the sea floor as well as the effect of the water column and sediments thickness on signal propagation. Ocean generated seismic ambient noise recorded at the seafloor appears to behave differently in deep and shallow water and 3D simulations of acoustic/seismic wave propagation look particularly promising for reconciling deep ocean, shelf and land seismic observations.

Searching for tremor in seismic noise on the 84 OBS (Ocean Bottom Seismometers) and 40 Land Seismometers, 3 months deployment in the Lesser Antilles subduction

NASA Astrophysics Data System (ADS)

Becel, A.; Diaz, J.; Laigle, M.; L. A. S. T., T.

2008-12-01

THALES, L.A.S.T., stands for Lesser Antilles Subduction zone Team of the THALES WAS RIGHT project (Coord. A. Hirn) of the European Union FP6, which gathers the scientific teams of a cluster of surveys and cruises in 2007. This cluster comprises the German cruise TRAIL with the vessel F/S Merian (PI E. Flueh and H. Kopp, IFM-GEOMAR), the French cruise SISMANTILLES 2 with the IFREMER vessel N/O Atalante (PI M. Laigle, IPG Paris and JF. Lebrun, Univ. Antilles Guyane), and French cruise OBSANTILLES with the IRD vessel N/O Antea (PI P. Charvis, Geoazur, Nice, France). Presentation T53A-1109 at last year, 2007 AGU Fall Meeting, of THALES, L.A.S.T. summarized the goals and first results of these experiments dedicated specifically to image at depth the seismic structure and activity of this subduction zone segment, which comprised: - MCS, multi-channel reflection seismic profiles as well as coincident multi-beam bathymetry that have been collected for 3700 km along a grid comprising 300 km along strike from North of Guadeloupe to Martinique islands and extending 150 km offshore over the forearc and accretionary wedge. - 84 OBSs at the nodes of this grid of profiles and 40 land stations. These instruments recorded the marine shots for a coincident refraction survey. They recorded local seismicity for precise location and focal mechanisms. The recovery of the continuous recording at this dense and extensive set of temporary sensors (1), recently completed allows to initiate an analysis of the continuously recorded seismic noise. Changes and transients of the noise character, and their possible correlations among instruments in the array will be searched for in the view of checking evidence of possible seismic tremor episodes or seismic transients, as have been described elsewhere with the specific aspect that most observations were acquired at sea-bottom as the forearc extends here broadly offshore. Preliminary results will be documented. (1) During these cruises and surveys, 84 Ocean Bottom multi-components Seismometers (OBS) have been brought together from several pools (Geosciences Azur, INSU-IPGP, IFM-GEOMAR, AWI), with up to 40 land stations (CSIC Barcelona, IPG-Paris, INSU-RLBM and LITHOSCOPE), for 3 months in early 2007, with a lesser number of instruments for similar period before and after. Support for the surveys came principally by ANR Catastrophes Telluriques et Tsunamis (SUBSISMANTI) to IPGP, by the EU SALVADOR Programme of IFM-GEOMAR, the OBSISMER CPER project of IPGP, Région Martinique and EU-FEDER, as well as by the EU project THALES WAS RIGHT on the Antilles and Hellenic active subductions to which contribute IPG- Paris and Geosciences Azur (France), IFM-GEOMAR (Germany), ETH Zurich (Switzerland), CSIC Barcelona (Spain), Univ. Trieste (Italy) and NOA Athens (Greece).

Dr. Garry Latham - Seismometer Tracings Study - Moon - MSC

NASA Image and Video Library

1969-07-22

S69-39588 (20 July 1969) --- Dr. Garry Latham, with the Lamont Geological Observatory, studies seismometer tracings in the Mission Control Center?s ASEP control room. The electronic data was coming from the Passive Seismic Experiments Package which the Apollo 11 astronauts had just deployed on the surface of the moon. Dr. Lamont is the principal investigator for the PSEP, a component of the Early Apollo Scientific Experiments Package (EASEP). PSEP uses three long-period seismometers and one short-period vertical seismometer for measuring meteoroid impacts and moonquakes. Such data will be useful in determining the interior structure of the moon; for example, does the moon have a core and mantle like Earth? Here, the center trace shows evidence of activity on the moon. The PSEP was sensitive enough to pick up the footsteps of astronauts Neil A. Armstrong and Edwin E. Aldrin Jr. as they walked on the moon.

Dr. Garry Latham studies seismometer tracings from the moon

NASA Image and Video Library

1969-07-22

S69-39587 (20 July 1969) --- Dr. Garry Latham (left) with the Lamont Geological Observatory, studies seismometer tracings in the Mission Control Center's (MCC) ALSEP control room. The electronic data was coming from the Passive Seismic Experiments Package (PSEP) which the Apollo 11 astronauts had just deployed on the surface of the moon. Dr. Lamont is the principal investigator for the PSEP, a component of the Early Apollo Scientific Experiments Package (EASEP). PSEP uses three long-period seismometers and one short-period vertical seismometer for measuring meteoroid impacts and moonquakes. Such data will be useful in determining the interior structure of the moon; for example, does the moon have a core and mantle like Earth? Here, the flapping of the PSEP's solar panels is picked up and registered as a tracing. The PSEP was sensitive enough to pick up the footsteps of astronauts Neil A. Armstrong and Edwin E. Aldrin Jr., as they walked on the moon.

First Observation of the Earth's Permanent Free Oscillations on Ocean Bottom Seismometers

NASA Astrophysics Data System (ADS)

Deen, M.; Wielandt, E.; Stutzmann, E.; Crawford, W.; Barruol, G.; Sigloch, K.

2017-11-01

The Earth's hum is the permanent free oscillations of the Earth recorded in the absence of earthquakes, at periods above 30 s. We present the first observations of its fundamental spheroidal eigenmodes on broadband ocean bottom seismometers (OBSs) in the Indian Ocean. At the ocean bottom, the effects of ocean infragravity waves (compliance) and seafloor currents (tilt) overshadow the hum. In our experiment, data are also affected by electronic glitches. We remove these signals from the seismic trace by subtracting average glitch signals; performing a linear regression; and using frequency-dependent response functions between pressure, horizontal, and vertical seismic components. This reduces the long period noise on the OBS to the level of a good land station. Finally, by windowing the autocorrelation to include only the direct arrival, the first and second orbits around the Earth, and by calculating its Fourier transform, we clearly observe the eigenmodes at the ocean bottom.

Seismicity detection around the subduting seamount off Ibaraki the Japan Trench using dense OBS array data

NASA Astrophysics Data System (ADS)

Nakatani, Y.; Mochizuki, K.; Shinohara, M.; Yamada, T.; Hino, R.; Ito, Y.; Murai, Y.; Sato, T.

2013-12-01

A subducting seamount which has a height of about 3 km was revealed off Ibaraki in the Japan Trench by a seismic survey (Mochizuki et al., 2008). Mochizuki et al. (2008) also interpreted that interplate coupling was weak over the seamount because seismicity was low and the slip of the recent large earthquake did not propagate over it. To carry out further investigation, we deployed dense ocean bottom seismometers (OBSs) array around the seamount for about a year. During the observation period, seismicity off Ibaraki was activated due to the occurrence of the 2011 Tohoku earthquake. The southern edge of the mainshock rupture area was considered to be located around off Ibaraki by many source analyses. Moreover, Kubo et al. (2013) proposes the seamount played an important role in the rupture termination of the largest aftershock. Therefore, in this study, we try to understand about spatiotemporal variation of seismicity around the seamount before and after the Mw 9.0 event as a first step to elucidate relationship between the subducting seamount and seismogenic behavior. We used velocity waveforms of 1 Hz long-term OBSs which were densely deployed at station intervals of about 6 km. The sampling rate is 200 Hz and the observation period is from October 16, 2010 to September 19, 2011. Because of the ambient noise and effects of thick seafloor sediments, it is difficult to apply methods which have been used to on-land observational data for detecting seismicity to OBS data and to handle continuous waveforms automatically. We therefore apply back-projection method (e.g., Kiser and Ishii, 2012) to OBS waveform data which estimate energy-release source by stacking waveforms. Among many back-projection methods, we adopt a semblance analysis (e.g., Honda et al., 2008) which can detect feeble waves. First of all, we constructed a 3-D velocity structure model off Ibaraki by compiling the results of marine seismic surveys (e.g., Nakahigashi et al., 2012). Then, we divided a target area into small areas and calculated P-wave traveltimes between each station and all small areas by fast marching method (Rawlinson et al., 2006). After constructing theoretical travel-time tables, we applied a proper frequency filter to the observed waveforms and estimated seismic energy release by projecting semblance values. As the result of applying our method, we could successfully detect magnitude 2-3 earthquakes.

Shear-wave velocity of marine sediments offshore Taiwan using ambient seismic noise

NASA Astrophysics Data System (ADS)

Lin, Yu-Tse; Lin, Jing-Yi; Kuo-Chen, Hao; Yeh, Yi-Chin; Cheng, Win-Bin

2017-04-01

Seismic ambient noise technology has many advantages over the traditional two-station method. The most important one is that noise is happening all the time and it can be widely and evenly distributed. Thus, the Green's Function of any station pair can be obtained through the data cross-correlation process. Many related studies have been performed to estimate the velocity structures based on the inland area. Only a few studies were reported for the marine area due to the relatively shorter recording time of ocean bottom seismometers (OBS) deployment and the high cost of the marine experiment. However, the understanding about the shear-wave velocity (Vs) of the marine sediments is very crucial for the hazard assessment related to submarine landslides, particularly with the growing of submarine resources exploration. In this study, we applied the ambient noise technique to four OBS seismic networks located offshore Taiwan in the aim of getting more information about the noise sources and having the preliminary estimation for the Vs of the marine sediments. Two of the seismic networks were deployed in the NE part of Taiwan, near the Ryukyu subduction system, whereas the others were in the SW area, on the continental margin rich in gas hydrate. Generally, ambient seismic noise could be associated with wind, ocean waves, rock fracturing and anthropogenic activity. In the southwestern Taiwan, the cross-correlation function obtained from two seismic networks indicate similar direction, suggestion that the source from the south part of the network could be the origin of the noise. However, the two networks in the northeastern Taiwan show various source direction, which could be caused by the abrupt change of bathymetry or the volcanic degassing effect frequently observed by the marine geophysical method in the area. The Vs determined from the dispersion curve shows a relatively higher value for the networks in the Okinawa Trough (OT) off NE Taiwan than that in the continental margin offshore SW Taiwan. This observation could be linked to the presence of numerous volcanic outcrops in the shallow marine sediments is the OT area. By comparing the 1-D velocity shear-wave profile with the previous studies, we found that the low Vs area could be associated with a sedimentary layer filled with gas in the OT and the creeping area along the continental margin. The Vs range estimated from our study also shows a good agreement with the velocity profile obtained based on the OBS seismic refraction experiment, suggesting that this method could be a more economical and effective way for the acquisition of the Vs parameters.

Broad-band BOS (BBYB) development and calibration in Taiwan

NASA Astrophysics Data System (ADS)

Lin, C. R.; Wang, C. C.; Kuo, B. Y.; Chen, P.; Jang, J. P.; Chang, H.; Laio, Y. C.; Chang, K. H.; Lin, F. S.

2016-12-01

Since 2009, combine with Academia Sinica, National Applied Research Laboratories and National Sun Yat-sen University formed ocean bottom seismograph (OBS) development team to develop sub-broadband OBS (called Yardbird OBS). Through a series deploy experiment at seafloor offshore Taiwan that got a lot of data can be used to study plate tectonics, seismic activity, source characteristics. Nowadays they have pretty good results already. Due to bandwidth limitations of the Yardbird OBS that inadequate to use for analyze global-scale earthquake. Therefor developing broadband ocean bottom seismograph is an important goal for the development team. Currently the broadband OBS (called BBYB) design and construction have completed the initial experiment phase. Due to underwater instruments always got high risk. Something accidentally making equipment sank in the sea cannot be recovery. Even recovery of equipment may also be causing poor performance because there is no data record. It cannot be to accomplish the experiment mission. In order to improve the OBS performance, avoid OBS dis-recovery or data collection is incomplete, must be sure all OBS's each component (such as seismic data recording device, balanced body, sonar dashboard, instruments and internal wiring ...) with well-done quality before assembly. Each component could go through very rigorous testing, strict and pick out the good components in the assembly process. Be sure all of produce the OBS under the water after a long deployment could successful recovery and got valuable data. In this presentation we will show a serial testing procedure and results for quality each BBYB component. Such as: Data logger: digitizer sensitivity, sampling rate, clock timing. Acoustic controller: function of Enable, Disable, Range, Release 1, Release 2, Option 1(Release disable). Air pressure gauge for glass ball: accuracy. A check lists of connector wiring check for assembling instrument. Design deploy and recovery procedure for operation on deck. We hope through repeated testing to ensure perfect performance of BBYB and apply the testing concept to another equipment for improve instruments performance. Keywords: ocean bottom seismograph (OBS); Data logger; Acoustic controller; Air pressure gauge.

Seismometer reading from impact made by Lunar Module ascent stage

NASA Technical Reports Server (NTRS)

1969-01-01

The seismometer reading from the impact made by the Lunar Module ascent stage when it struck the lunar surface. The impact was registered by the Passive Seismic Experiment Package (PSEP) which was deployed on the Moon by the Apollo 12 astronauts. The Lunar module's ascent stage was jettisoned and sent toward impact on the Moon after Astronauts Charles Conrad Jr. and Alan L. Bean returned to lunar orbit and rejoined Astronaut Richard F. Gordon Jr., in the Command/Service Modules.

Towards a first design of a Newtonian-noise cancellation system for Advanced LIGO

NASA Astrophysics Data System (ADS)

Coughlin, M.; Mukund, N.; Harms, J.; Driggers, J.; Adhikari, R.; Mitra, S.

2016-12-01

Newtonian gravitational noise from seismic fields is predicted to be a limiting noise source at low frequency for second generation gravitational-wave detectors. Mitigation of this noise will be achieved by Wiener filtering using arrays of seismometers deployed in the vicinity of all test masses. In this work, we present optimized configurations of seismometer arrays using a variety of simplified models of the seismic field based on seismic observations at LIGO Hanford. The model that best fits the seismic measurements leads to noise reduction limited predominantly by seismometer self-noise. A first simplified design of seismic arrays for Newtonian-noise cancellation at the LIGO sites is presented, which suggests that it will be sufficient to monitor surface displacement inside the buildings.

Improving OBS operations in ultra-deep ocean during the Southern Mariana Trench expeditions

NASA Astrophysics Data System (ADS)

Zeng, X.; Lin, J.; Xu, M.; Zhou, Z.

2017-12-01

The Mariana Trench Research Initiative, led by the South China Sea Institute of Oceanology of the Chinese Academy of Sciences and through international collaboration, focuses on investigating the deep and shallow lithospheric structure, earthquake characteristics, extreme geological environments, and the controlling geodynamic mechanisms for the formation of Earth's deepest basins in the southern Mariana Trench. Two multidisciplinary research expeditions were executed during December 2016 and June 2017, respectively, on board R/V Shiyan 3. A main task of the Mariana Initiative is to conduct the Southern Mariana OBS Experiment (SMOE), the first OBS seismic experiment across the Challenger Deep. The SMOE expeditions include both active and passive source seismic experiments and employed a large number of broadband OBS instruments. Due to the deep water, rough weather, strong winds, and other unfavorable factors, it was challenging to deploy/recover the OBSs. During the two expeditions we developed and experimented with a number of ways to improve the success rate of OBS operations in the harsh ultra-deep ocean environment of the Southern Mariana Trench. All newly acquired OBSs underwent a series of uniquely designed deep-ocean tests to improve the instrument performance and maximize reliability during their deployment under the ultra-high pressure conditions. The OBS deployment and recovery followed a unified standard operation procedure and aided by an instrumental checklist, which were specifically designed and strictly enforced for operation during the expeditions. Furthermore, an advanced ship-based radio positioning system was developed to rapidly and accurately locate the OBS instruments when they reached the sea surface; the system proved its effectiveness even under extreme weather conditions. Through the development and application of the novel methods for operation in deep oceans, we overcame the rough sea and other unfavorable factors during the first two expeditions to the southern Mariana Trench and achieved a highly successful OBS operation program.

RHUM-RUM investigates La Réunion mantle plume from crust to core

NASA Astrophysics Data System (ADS)

Sigloch, Karin; Barruol, Guilhem

2013-04-01

RHUM-RUM (Réunion Hotspot and Upper Mantle - Réunions Unterer Mantel) is a French-German passive seismic experiment designed to image an oceanic mantle plume - or lack of plume - from crust to core beneath La Réunion Island, and to understand these results in terms of material, heat flow and plume dynamics. La Réunion hotspot is one of the most active volcanoes in the world, and its hotspot track leads unambiguously to the Deccan Traps of India, one of the largest flood basalt provinces on Earth, which erupted 65 Ma ago. The genesis and the origin at depth of the mantle upwelling and of the hotspot are still very controversial. In the RHUM-RUM project, 57 German and French ocean-bottom seismometers (OBS) are deployed over an area of 2000 km x 2000 km2 centered on La Réunion Island, using the "Marion Dufresne" and "Meteor" vessels. The one-year OBS deployment (Oct. 2012 - Oct. 2013) will be augmented by terrestrial deployments in the Iles Eparses in the Mozambique Channel, in Madagascar, Seychelles, Mauritius, Rodrigues and La Réunion islands. A significant number of OBS will be also distributed along the Central and South West Indian Ridges to image the lower-mantle beneath the hotspot, but also to provide independent opportunity for the study of these slow to ultra-slow ridges and of possible plume-ridge interactions. RHUM-RUM aims to characterize the vertically ascending flow in the plume conduit, as well as any lateral flow spreading into the asthenosphere beneath the western Indian Ocean. We want to establish the origin of the heat source that has been fueling this powerful hotspot, by answering the following questions: Is there a direct, isolated conduit into the deepest mantle, which sources its heat and material from the core-mantle boundary? Is there a plume connection to the African superswell at mid-mantle depths? Might the volcanism reflect merely an upper mantle instability? RHUM-RUM also aims at studying the hotspot's interaction with the neighboring ridges of the Indian Ocean. There is in particular a long-standing hypothesis, not yet examined seismically, that channelized plume flow beneath the aseismic Rodrigues Ridge could feed the Central Indian Ridge at 1000 km distance. The RHUM-RUM group (www.rhum-rum.net): * IPG Paris & Géosciences Réunion: G. Barruol, J.P. Montagner, E. Stutzmann, F.R. Fontaine, C. Deplus, M. Cannat, G. Roult, J. Dyment, S. Singh, W. Crawford, C. Farnetani, N. Villeneuve, L. Michon. V. Ferrazzini, Y. Capdeville. * Univ. Munich (LMU): K. Sigloch, H. Igel. AWI Bremerhaven: V. Schlindwein. Univ. Frankfurt: G. Rümpker. Univ. Münster: C. Thomas. Univ. Bonn: S. Miller. * Géosciences Montpellier: C. Tiberi, A. Tommasi, D. Arcay, C. Thoraval. * Mauritius Oceanography Institute: D. Bissessur. Univ. Antananarivo: G. Rambolamanana. SEYPEC Seychelles Petroleum: P. Samson, P. Joseph. * Other institutes: A. Davaille, M. Jegen, M. Maia, G. Nolet, D. Sauter, B. Steinberger.

RHUM-RUM investigates La Réunion mantle plume from crust to core

NASA Astrophysics Data System (ADS)

Sigloch, K.; Barruol, G.

2012-12-01

RHUM-RUM (Réunion Hotspot and Upper Mantle - Réunions Unterer Mantel) is a French-German passive seismic experiment designed to image an oceanic mantle plume - or lack of plume - from crust to core beneath La Réunion Island, and to understand these results in terms of material, heat flow and plume dynamics. La Réunion hotspot is one of the most active volcanoes in the world, and its hotspot track leads unambiguously to the Deccan Traps of India, one of the largest flood basalt provinces on Earth, which erupted 65 Ma ago. The genesis and the origin at depth of the mantle upwelling and of the hotspot are still very controversial. In the RHUM-RUM project, 57 German and French ocean-bottom seismometers (OBS) are deployed over an area of 2000 km x 2000 km2 centered on La Réunion Island, using the "Marion Dufresne" and "Meteor" vessels. The one-year OBS deployment (Oct. 2012 - Oct. 2013) will be augmented by terrestrial deployments in the Iles Eparses in the Mozambique Channel, in Madagascar, Seychelles, Mauritius, Rodrigues and La Réunion islands. A significant number of OBS will be also distributed along the Central and South West Indian Ridges to image the lower-mantle beneath the hotspot, but also to provide independent opportunity for the study of these slow to ultra-slow ridges and of possible plume-ridge interactions. RHUM-RUM aims to characterize the vertically ascending flow in the plume conduit, as well as any lateral flow spreading into the asthenosphere beneath the western Indian Ocean. We want to establish the origin of the heat source that has been fueling this powerful hotspot, by answering the following questions: Is there a direct, isolated conduit into the deepest mantle, which sources its heat and material from the core-mantle boundary? Is there a plume connection to the African superswell at mid-mantle depths? Might the volcanism reflect merely an upper mantle instability? RHUM-RUM also aims at studying the hotspot's interaction with the neighboring ridges of the Indian Ocean. There is in particular a long-standing hypothesis, not yet examined seismically, that channelized plume flow beneath the aseismic Rodrigues Ridge could feed the Central Indian Ridge at 1000 km distance. The RHUM-RUM group (www.rhum-rum.net): * IPG Paris & Géosciences Réunion: G. Barruol, J.P. Montagner, E. Stutzmann, F.R. Fontaine, C. Deplus, M. Cannat, G. Roult, J. Dyment, S. Singh, W. Crawford, C. Farnetani, N. Villeneuve, L. Michon. V. Ferrazzini, Y. Capdeville. * Univ. Munich (LMU): K. Sigloch, H. Igel. AWI Bremerhaven: V. Schlindwein. Univ. Frankfurt: G. Rümpker. Univ. Münster: C. Thomas. Univ. Bonn: S. Miller. * Géosciences Montpellier: C. Tiberi, A. Tommasi, D. Arcay, C. Thoraval. * Mauritius Oceanography Institute: D. Bissessur. Univ. Antananarivo: G. Rambolamanana. SEYPEC Seychelles Petroleum: P. Samson, P. Joseph. * Other institutes: A. Davaille, M. Jegen, M. Maia, G. Nolet, D. Sauter, B. Steinberger.

Newberry Seismic Deployment Fieldwork Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, J; Templeton, D C

2012-03-21

This report summarizes the seismic deployment of Lawrence Livermore National Laboratory (LLNL) Geotech GS-13 short-period seismometers at the Newberry Enhanced Geothermal System (EGS) Demonstration site located in Central Oregon. This Department of Energy (DOE) demonstration project is managed by AltaRock Energy Inc. AltaRock Energy had previously deployed Geospace GS-11D geophones at the Newberry EGS Demonstration site, however the quality of the seismic data was somewhat low. The purpose of the LLNL deployment was to install more sensitive sensors which would record higher quality seismic data for use in future seismic studies, such as ambient noise correlation, matched field processing earthquakemore » detection studies, and general EGS microearthquake studies. For the LLNL deployment, seven three-component seismic stations were installed around the proposed AltaRock Energy stimulation well. The LLNL seismic sensors were connected to AltaRock Energy Gueralp CMG-DM24 digitizers, which are powered by AltaRock Energy solar panels and batteries. The deployment took four days in two phases. In phase I, the sites were identified, a cavity approximately 3 feet deep was dug and a flat concrete pad oriented to true North was made for each site. In phase II, we installed three single component GS-13 seismometers at each site, quality controlled the data to ensure that each station was recording data properly, and filled in each cavity with native soil.« less

Seismic Attenuation of Teleseismic Body Waves in Cascadia, Measured on the Amphibious Array

NASA Astrophysics Data System (ADS)

Eilon, Z.; Abers, G. A.

2015-12-01

Fundamental questions remain about the nature of the asthenosphere, including its dynamical relationship to overlying lithosphere, melt content, and entrainment in subduction zones. We examine the evolution of this low-velocity, highly attenuating layer using data from the Cascadia Initiative's Amphibious Array, which provides unprecedented coverage of an oceanic plate from ridge crest to trench to sub-arc. Our study extends the suite of measurements achievable with OBS data, augmenting traditional travel time analysis with integrated attenuation data that are a powerful tool for imaging melt/fluids and the variation of asthenospheric character with age. Cooling models, coupled with experimentally-derived anelastic scaling relationships, indicate that thermal gradients should cause appreciable decrease in attenuation of teleseismic body waves with increasing age. This long-wavelength cooling trend may be perturbed by highly attenuating melt or volatiles concentrated at the ridge axis or beneath the Cascades arc, depending on melt fraction and pore geometry. Attenuation beyond the trench should be a strong function of the fate of asthenospheric entrainment beneath subducted plates, with implications for mass transfer to the deep mantle as well as recent models of sub-slab anisotropy. The Amphibious Array, with <70 km spacing of OBS and on-land broadband seismometers deployed between 2011 and 2015, provides a dataset of ~1 x 105 arrivals from ~700 Mw>6.0 teleseismic earthquakes. We use a spectral ratio method to compute differential attenuation (Δt*) from body wave teleseisms recorded at OBS and land stations, allowing us to estimate path-integrated quality factor in the upper mantle. Preliminary results reveal variations of ~3 s in differential travel time and >0.5 s in ΔtS* across the 0-10 Ma oceanic plate, demonstrating the strong thermal control on anelasticity. Large values of Δt* observed east of the trench may indicate entrainment of highly attenuating asthenosphere during subduction, although more work is required to categorize and remove the signal of the overriding plate. This work complements previous studies using surface waves and contributes to our developing understanding of anelastic controls on seismic parameters by probing the Earth in a different frequency range.

Gas expulsions and biological activity recorded offshore Molene Island, Brittany (France): video supervised recording of OBS data and analogue modelling

NASA Astrophysics Data System (ADS)

Klingelhoefer, F.; Géli, L.; Dellong, D.; Evangelia, B.; Tary, J. B.; Bayrakci, G.; Lantéri, N.; Lin, J. Y.; Chen, Y. F.; Chang, E. T. Y.

2016-12-01

Ocean bottom seismometers (OBS) commonly record signals from Short Duration Events (SDEs), having characteristics that are very different from those produced by tectonic earthquakes, e.g.: durations < 1 s, frequencies between 10 and 30 Hz, and one single-wave trains, with no identified P- nor S-wave arrivals. SDES were first reported by Burkisk et al (1981) who proposed biological activity as a possible cause. Since then, SDEs have been disregarded or discarded as noise by scientists interested in earthquake studies. Interest in SDEs came back recently, when it was realized that SDEs are commonly found and could be due to gas expulsions from the seafloor. To discriminate between the 2 hypotheses (biological activity vs gas emissions), different tests have been made, including seismic recordings combined with video surveillance and analogue experiments. In May 2016, two OBS (4.5 Hz) were deployed offshore Molene Island, Brittany within the field of view of the EMSO-Molene underwater observatory, at a water depth of 12 m. The camera images and the recordings reveal the presence of crabs, octopus and several species of fish. Other acoustic signals can be related to the presence of moving algae or the influence from bad weather. Tides produce characteristic curves in the noise recorded on the geophones. SDEs have been recorded on both instruments, that may well have been caused by gas expulsions from the seabed into the water. In order to verify this hypothesis, an aquarium was filled with water overlying an even grain-sized quartz sand layer. A constant air supply through a narrow tube produced gas bubbles in a regular manner and an immersed ocean bottom geophone recorded the resulting acoustic signals. The bubbles tend to have a uniform size and to produce a waveform very close to those found on the OBSs. By comparing the number of SDEs and the volume of escaped air, estimates can be made regarding the volume of gas escaping the seafloor in different environments.

Shake It All About! Using Earthquake Science to Enhance Geology and Physics Teaching in the UK

ERIC Educational Resources Information Center

Murphy, Phillip; Murphy, Elizabeth

2014-01-01

A three-year project aimed at embedding seismology into schools in northern England to support the teaching of the earth science strands in the National Curriculum for England and Wales is described. Seismometers were deployed in a range of high schools across the Yorkshire and Humberside region. Deployment was supported by a programme of staff…

Real-Time Seismic Data from the Bottom Sea

PubMed Central

Roset, Xavier; Trullols, Enric; Artero-Delgado, Carola; Prat, Joana; Massana, Immaculada; Carbonell, Montserrat; Barco de la Torre, Jaime; Toma, Daniel Mihai

2018-01-01

An anchored marine seismometer, acquiring real-time seismic data, has been built and tested. The system consists of an underwater seismometer, a surface buoy, and a mooring line that connects them. Inductive communication through the mooring line provides an inexpensive, reliable, and flexible solution. Prior to the deployment the dynamics of the system have been simulated numerically in order to find optimal materials, cables, buoys, and connections under critical marine conditions. The seismometer used is a high sensitivity triaxial broadband geophone able to measure low vibrational signals produced by the underwater seismic events. The power to operate the surface buoy is provided by solar panels. Additional batteries are needed for the underwater unit. In this paper we also present the first results and an earthquake detection of a prototype system that demonstrates the feasibility of this concept. The seismometer transmits continuous data at a rate of 1000 bps to a controller equipped with a radio link in the surface buoy. A GPS receiver on the surface buoy has been configured to perform accurate timestamps on the seismic data, which makes it possible to integrate the seismic data from these marine seismometers into the existing seismic network. PMID:29642479

Real-Time Seismic Data from the Bottom Sea.

PubMed

Roset, Xavier; Trullols, Enric; Artero-Delgado, Carola; Prat, Joana; Del Río, Joaquin; Massana, Immaculada; Carbonell, Montserrat; Barco de la Torre, Jaime; Toma, Daniel Mihai

2018-04-08

An anchored marine seismometer, acquiring real-time seismic data, has been built and tested. The system consists of an underwater seismometer, a surface buoy, and a mooring line that connects them. Inductive communication through the mooring line provides an inexpensive, reliable, and flexible solution. Prior to the deployment the dynamics of the system have been simulated numerically in order to find optimal materials, cables, buoys, and connections under critical marine conditions. The seismometer used is a high sensitivity triaxial broadband geophone able to measure low vibrational signals produced by the underwater seismic events. The power to operate the surface buoy is provided by solar panels. Additional batteries are needed for the underwater unit. In this paper we also present the first results and an earthquake detection of a prototype system that demonstrates the feasibility of this concept. The seismometer transmits continuous data at a rate of 1000 bps to a controller equipped with a radio link in the surface buoy. A GPS receiver on the surface buoy has been configured to perform accurate timestamps on the seismic data, which makes it possible to integrate the seismic data from these marine seismometers into the existing seismic network.

Marine Seismic System Deployment (MSS). Phase 2. Investigation of Techniques and Deployment Scenarios for Installation of Triaxial Seismometer in a Borehole in the Deep Ocean

DTIC Science & Technology

1981-01-09

CHALLENGER for an estimated period of six days. The design for the test Borehole Instrumentation Package (BIP) reentry-sub and associated handling...equipment has been completed ard hmi been submitted for vendor bid. Details of the specialized support equipment for installation on the GLOMAR CHALLENGER ...developed under the direction of the Deep Sea Drilling Project (DSDP) by the dynamically positioned drilling vessel GLOMAR CHALLENGER . Deployment of the

Broadband seismic noise attenuation versus depth at the Albuquerque Seismological Laboratory

USGS Publications Warehouse

Hutt, Charles R.; Ringler, Adam; Gee, Lind

2017-01-01

Seismic noise induced by atmospheric processes such as wind and pressure changes can be a major contributor to the background noise observed in many seismograph stations, especially those installed at or near the surface. Cultural noise such as vehicle traffic or nearby buildings with air handling equipment also contributes to seismic background noise. Such noise sources fundamentally limit our ability to resolve earthquake‐generated signals. Many previous seismic noise versus depth studies focused separately on either high‐frequency (>1  Hz">>1  Hz) or low‐frequency (<0.05  Hz"><0.05  Hz) bands. In this study, we use modern high‐quality broadband (BB) and very broadband (VBB) seismometers installed at depths ranging from 1.5 to 188 m at the Albuquerque Seismological Laboratory to evaluate noise attenuation as a function of depth over a broad range of frequencies (0.002–50 Hz). Many modern seismometer deployments use BB or VBB seismometers installed at various depths, depending on the application. These depths range from one‐half meter or less in aftershock study deployments, to one or two meters in the Incorporated Research Institutions for Seismology Transportable Array (TA), to a few meters (shallow surface vaults) up to 100 m or more (boreholes) in the permanent observatories of the Global Seismographic Network (GSN). It is important for managers and planners of these and similar arrays and networks of seismograph stations to understand the attenuation of surface‐generated noise versus depth so that they can achieve desired performance goals within their budgets as well as their frequency band of focus. The results of this study will assist in decisions regarding BB and VBB seismometer installation depths. In general, we find that greater installation depths are better and seismometer emplacement in hard rock is better than in soil. Attenuation for any given depth varies with frequency. More specifically, we find that the dependence of depth will be application dependent based on the frequency band and sensitive axes of interest. For quick deployments (like aftershock studies), 1 m may be deep enough to produce good data, especially when the focus is on vertical data where temperature stability fundamentally limits the low‐frequency noise levels and little low‐frequency data will be used. For temporary (medium‐term) deployments (e.g., TA) where low cost can be very important, 2–3 m should be sufficient, but such shallow installations will limit the ability to resolve low‐frequency signals, especially on horizontal components. Of course, one should try for maximum burial depth within the budget when there is interest in using the data for low‐frequency applications. For long‐term deployments like the permanent observatories of the GSN and similar networks, 100–200 m depth in hard rock is desirable to achieve lowest noise, although 30–60 m may be acceptable.

New Insights on the Structure of the Cascadia Subduction Zone from Amphibious Seismic Data

NASA Astrophysics Data System (ADS)

Janiszewski, Helen Anne

A new onshore-offshore seismic dataset from the Cascadia subduction zone was used to characterize mantle lithosphere structure from the ridge to the volcanic arc, and plate interface structure offshore within the seismogenic zone. The Cascadia Initiative (CI) covered the Juan de Fuca plate offshore the northwest coast of the United States with an ocean bottom seismometer (OBS) array for four years; this was complemented by a simultaneous onshore seismic array. Teleseismic data recorded by this array allows the unprecedented imaging of an entire tectonic plate from its creation at the ridge through subduction initiation and back beyond the volcanic arc along the entire strike of the Cascadia subduction zone. Higher frequency active source seismic data also provides constraints on the crustal structure along the plate interface offshore. Two seismic datasets were used to image the plate interface structure along a line extending 100 km offshore central Washington. These are wide-angle reflections from ship-to-shore seismic data from the Ridge-To-Trench seismic cruise and receiver functions calculated from a densely spaced CI OBS focus array in a similar region. Active source seismic observations are consistent with reflections from the plate interface offshore indicating the presence of a P-wave velocity discontinuity. Until recently, there has been limited success in using the receiver function technique on OBS data. I avoid these traditional challenges by using OBS constructed with shielding deployed in shallow water on the continental shelf. These data have quieter horizontals and avoid water- and sediment-multiple contamination at the examined frequencies. The receiver functions are consistently modeled with a velocity structure that has a low velocity zone (LVZ) with elevated P to S-wave velocity ratios at the plate interface. A similar LVZ structure has been observed onshore and interpreted as a combination of elevated pore-fluid pressures or metasediments. This new offshore result indicates that the structure may persist updip indicating the plate interface may be weak. To focus more broadly on the entire subduction system, I calculate phase velocities from teleseismic Rayleigh waves from 20-100 s period across the entire onshore-offshore array. The shear-wave velocity model calculated from these data can provide constrains on the thermal structure of the lithosphere both prior to and during subduction of the Juan de Fuca plate. Using OBS data in this period band requires removal of tilt and compliance noise, two types of water-induced noise that affect long period data. To facilitate these corrections on large seismic arrays such as the CI, an automated quality control routine was developed for selecting noise windows for the calculation of the required transfer functions. These corrections typically involve either averaging out transient signals, which requires the assumption of stationarity of the noise over the long periods of time, or laborious hand selection of noise segments. This new method calculates transfer functions based on daily time series that exclude transient signals, but allows for the investigation of long-term variation over the course of an instrument's deployment. I interpret these new shoreline-crossing phase velocity maps in terms of the tectonics associated with the Cascadia subduction system. Major findings include that oceanic plate cooling models do not explain the velocities observed beneath the Juan de Fuca plate, that slow velocities in the forearc appear to be more prevalent in areas modeled to have experienced high slip in past Cascadia megathrust earthquakes, and along strike variations in phase velocity reflect variations in arc structure and backarc tectonics.

Posthole Sensor Performance in the USArray Transportable Array - Results from Testing and Initial Deployments in Alaska and Canada

NASA Astrophysics Data System (ADS)

Frassetto, A.; Busby, R. W.; Hafner, K.; Sauter, A.; Woodward, R.

2014-12-01

To prepare for the deployment of EarthScope's USArray Transportable Array (TA) in Alaska and adjacent Canada over the next several years, IRIS has evaluated different strategies for emplacing posthole seismometers. The goal of this work has been to maintain or enhance a TA station's noise performance while reducing the weight and logistical considerations required for its installation. Motivating this research are developments in posthole broadband seismometer design and the unique conditions for operating in this region, where many potential sites are located on frost-fractured outcrops or underlain by permafrost, in either case only accessible by helicopter. Current emplacement methods use a portable rig to auger or hammer-drill a hole 2.5-5 meters deep, in unconsolidated materials and permafrost, or by diamond bit coring 1-3 meters into rock. These emplacements are used at new TA installations and upgrades to existing AK network stations, and we compare their performance to the lower-48 TA vault installations. Through July 2014 there are eight TA and six upgraded AK stations operating under USArray; including five since at least October 2012, providing a detailed record of seasonal and/or site-specific behavior. We also discuss testing of different downhole configurations for 13 stations deployed at Piñon Flat Observatory in California since April 2014. Station performance is presented and compared using probability density functions summed from hourly power spectral density calculations. These are computed for the continuous time series of seismic data recorded on each seismic channel. Our results show that the noise performance of seismometers in Alaska with cased- or core- hole installations sometimes exceeds that of the quietest TA stations in the lower-48, particularly for the horizontal channels at long periods. We analyze and discuss the performance of example stations, comparing to other nearby seismometers. We also examine the performance of AK stations before and after they have been converted from surface vault to posthole configuration. At Piñon Flat, different methods for packing the seismometer and clamping its cables within cased holes has guided development of field procedure. The new posthole emplacements generally improve upon the mean performance of the lower-48 TA vaults.

Local Seismicity Recorded by ChilePEPPER: Implications for Dynamic Accretionary Prism Response and Long-term Prism Evolution

NASA Astrophysics Data System (ADS)

de Moor, A.; Trehu, A. M.; Tryon, M. D.

2015-12-01

To investigate the dynamic response of the outer accretionary wedge updip from the patch of greatest slip during the Mw8.8 2010 Maule earthquake, 10 Ocean Bottom Seismometers (OBS) were deployed from May 2012 to March 2013 in a small array with an inter-instrument spacing of ~12 km . Nine instruments were recovered, with 4 recording data on 3 intermediate-band 3-component seismometers and a differential pressure gauge and 5 recording data from absolute pressure gauges. [note: All instruments were also equipped with a fluid flow meter sensitive to flow rates as low as 0.0001 cm/yr in or out of the sediments. However, no flow signal was detected.] Here we present hypocenters for 569 local events that have S-P times less than 17 seconds (i.e. within ~125 km of the array) using hand-picked arrival times and a 1D velocity model derived from a 2D seismic refraction profile through the region (Moscoso et al 2011, EPSL). We analyze the distribution of seismicity in the context of published slip models, ChilePEPPER high-resolution seismic reflection data, critical taper analysis done by Cubas et al 2013 (EPSL), and offshore gravity data. The data show distinct segmentation within the outer prism. The northern section of the study area is characterized by a lack of seismicity, accretion of nearly all incoming sediment and a prism at critical taper. In contrast, abundant seismicity, significant sediment underthrusting at the deformation front and a prism below critical taper angle characterize the southern part of the study area. Both coseismic slip and post-rupture local seismicity can be related to density anomalies within the upper plate as revealed by free air gravity data corrected for the effects of bathymetry and the subducting plate. [ChilePEPPER - Project Evaluating Prism Post-Earthquake Response

MUG-OBS - Multiparameter Geophysical Ocean Bottom System : a new instrumental approach to monitor earthquakes.

NASA Astrophysics Data System (ADS)

Hello, Y.; Yegikyan, M.; Charvis, P.; Verfaillie, R.; Philippe, O.

2015-12-01

There are several attempts to monitor real time seismic activity, using regional scale wired nodes, such as Neptune in Canada and in the U.S, Antares in France or DONET in Japan.On another hand there are also initiatives in deploying repeatedly OBS array like during the amphibious Cascadia Initiative (four 1-year deployments), the Japanese Pacific Array (broadband OBSs "ocean-bottom broadband dispersion survey" with 2-years autonomy), the Obsismer program in the French Lesser Antilles (eight 6-months deployments) and the Osisec program in Ecuador (four 6-months deployments). These OBSs are autonomous, they are self-recovered or recovered using an ROV. These systems are costly including ship time, and require to recover the OBS before to start working on data.Among the most recent alternative we developed a 3-years autonomy OBS equipped with a Nanometrics Trillium 120 s, a triaxial accelerometer, a differential, an absolute pressure gauge, and a hydrophone. MUG-OBS is a free falling instrument rated down to 6000 m. The installation of the sensor is monitored by acoustic commands from the surface and a health bulletin with data checking is recovered by acoustic during the installation. The major innovation is that it is possible to recover the data any time on demand (regularly every 6-months or after a seismic crisis) utilizing one of the 6 data-shuttles released from the surface by acoustic command using a one day fast cruise boat of opportunity. Since sensors stayed at the same location for 3 years (when an OBS is redeployed on the same site, it will not land in the same place), it is a perfect tool to monitor slow seismic events, background seismic activity and aftershock distribution. Clock, drift measurement and GPS localization is automatic when the shuttle reaches the surface. A new version is being developed; for remote areas, shuttles released automatically and a seismic events bulletin is transmitted. Selected data can be recovered by two- way Iridium satellite communication. After a period of 3 years the main station is ­self-recovered by acoustic.

Planetary Seismology : Lander- and Wind-Induced Seismic Signals

NASA Astrophysics Data System (ADS)

Lorenz, Ralph

2016-10-01

Seismic measurements are of interest for future geophysical exploration of ocean worlds such as Europa or Titan, as well as Venus, Mars and the Moon. Even when a seismometer is deployed away from a lander (as in the case of Apollo) lander-generated disturbances are apparent. Such signatures may be usefully diagnostic of lander operations (at least for outreach), and may serve as seismic excitation for near-field propagation studies. The introduction of these 'spurious' events may also influence the performance of event detection and data compression algorithms.Examples of signatures in the Viking 2 seismometer record of lander mechanism operations are presented. The coherence of Viking seismometer noise levels and wind forcing is well-established : some detailed examples are examined. Wind noise is likely to be significant on future Mars missions such as InSight, as well as on Titan and Venus.

Measurement of seismometer orientation using the tangential P-wave receiver function based on harmonic decomposition

NASA Astrophysics Data System (ADS)

Lim, Hobin; Kim, YoungHee; Song, Teh-Ru Alex; Shen, Xuzhang

2018-03-01

Accurate determination of the seismometer orientation is a prerequisite for seismic studies including, but not limited to seismic anisotropy. While borehole seismometers on land produce seismic waveform data somewhat free of human-induced noise, they might have a drawback of an uncertain orientation. This study calculates a harmonic decomposition of teleseismic receiver functions from the P and PP phases and determines the orientation of a seismometer by minimizing a constant term in a harmonic expansion of tangential receiver functions in backazimuth near and at 0 s. This method normalizes the effect of seismic sources and determines the orientation of a seismometer without having to assume for an isotropic medium. Compared to the method of minimizing the amplitudes of a mean of the tangential receiver functions near and at 0 s, the method yields more accurate orientations in cases where the backazimuthal coverage of earthquake sources (even in the case of ocean bottom seismometers) is uneven and incomplete. We apply this method to data from the Korean seismic network (52 broad-band velocity seismometers, 30 of which are borehole sensors) to estimate the sensor orientation in the period of 2005-2016. We also track temporal changes in the sensor orientation through the change in the polarity and the amplitude of the tangential receiver function. Six borehole stations are confirmed to experience a significant orientation change (10°-180°) over the period of 10 yr. We demonstrate the usefulness of our method by estimating the orientation of ocean bottom sensors, which are known to have high noise level during the relatively short deployment period.

Anisotropy variety using and wave splitting analysis by using the integration of combine linear and circlcirculare air-gun shotshooting datasurvey in the gas hydrate-enriched continental slops area o,f southwestenSW Taiwan

NASA Astrophysics Data System (ADS)

Lin, Y. C.; Lin, J. Y.; Cheng, W. B.

2016-12-01

Linear seismic refraction analysis based on air- or GI- gun shootings were widely used to determine the velocity structures along 2-D profiles. The data acquisition along several profiles can provide a 3-D view and increases the knowledge related to the lateral variation for the geological structures. However, if the target area has restricted distribution, the structure may not be observed by large spacing seismic profiles. Furthermore, limited by the network geometry, it could be difficult to get the velocity variation for different azimuths. In this study, apart from traditional linear seismic profile shooting geometry, we applied a circular shooting track around a 4-components Ocean-Bottom seismometer (OBS) station deployed in 2014 and 2015 on the continental slops, a hydrate-enriched area in the SW Taiwan, with a radius of 1 mile and 1.5 mile respectively. The aim is to understand if the change of shooting geometry along a single station can provide lateral information about the bathymetry characteristics or velocity composition in the sediment. To better examine the spatial variation of our data, we first rotated the OBS records to the vertical (V), radial (R) and transverse (T) components based the 3-axie rotate method. Distinct changes in the signal intensity in T component were distinguished at depths of 4.5 second between 58-157 degrees and at depths of 4 second between 212-258 degrees. The OBS is located on a sedimentary wedge dipping northeastward, as evidenced by the multichannel reflection profiles shown in the previous study. The ongoing upward activity of the mud diapir do the generation this sedimentary wedge Thus, the appearance of these signals could be linked to the wave refraction from the layer of the wedge, where a clear velocity contrast could be expected. We recognized visible P-S converted phase in R component at depths of approximately at depth of 3.3 second. The time arrivals of the converted phases provide information for the estimation of S wave velocity, which could be a good indicator for the sediment strength. Based on the arrivals, we suggest that the formation of the converted wave should be linked to the bathymetry alteration. Our results show that the experiment along a circular shooting track could bring useful information about the anisotropy characteristics around the OBS site.

Seismarmara 2001: A Marine Seismic Survey and Offshore-onshore Artificial Source and Natural Earthquakes In The Seismogenic Region of The Sea of Marmara

NASA Astrophysics Data System (ADS)

Hirn, A.; Singh, S.; Charvis, P.; Géli, L.; Laigle, M.; Lépine, J.-C.; de Voogd, B.; Saatcilar, R.; Taymaz, T.; Ozalaybey, S.; Shimamura, H.; Selvi, O.; Karabulut, H.; Murai, Y.; Nishimura, Y.; Yamada, A.; Vigner, A.; Bazin, S.; Tan, O.; Yolsal, S.; Aktar, M.; Galvé, A.; Sapin, M.; Marthelot, J.-M.; Imren, C.; Ergin, M.; Tapirdamaz, C.; Koçaoglu, A.; Tarancioglu, A.; Diaz, J.; Verhille, J.; Auffret, Y.; Cetin, S.; Oçakoglu, N.; Karakoç, F.; Klien, E.; Ricolleau, A.; Selvigen, V.; Demirbag, E.; Hakyemez, Y.; Sarikawak, K.

SEISMARMARA is a Turkish-French survey carried out in July-October 2001 as a multi-method approach of seismic structure and activity of the Sea of Marmara. This is the segment of the North Anatolian Fault system that continues the one that produced the two destructive earthquakes in 1999 to the East, and is prone to future major earth- quakes as it has experienced in the past. Aims of the programme are to shed light on the regional tectonics and recent evolution at crustal scale, image faults by their structure and seismic activity, and provide a model and reference to improve loca- tion of earthquakes and focal mechanism studies. The programme bases on marine multichannel reflection seismics (MCS), ocean bottom seismometers (OBS) and land stations recording of wide-angle reflection-refraction from the same source, as well as recording of local earthquakes for tomography and stress/strain distribution. The French N/O Le Nadir acquired 4000 km of MCS profiles in the northern Sea of Mar- mara, using a 4.5 km long digital streamer with 360-channels and sources of 8100 cu. in., or 2900 cu. in., provided by a 12-airgun array in single-bubble mode. Navigation safety was provided by a vessel of the Turkish Coast Guards (Sahil Güvenlik), Leg 1 comprises 4 E-W lines and 30 cross-lines in the whole Marmara Trough, leg 2 has 1 been devoted to a very dense grid of lines in the Cinarcik basin and its margins, record- ing over 80 dip-lines at 0.6-0.9 km spacing At sea-bottom 38 OBS, with 3-component sensors and continuous recording over 1 to 2-month in order to also record natural earthquakes were deployed and collected by the Turkish ship MTA Sismik-1. On land the permanent array has been complemented by as many temporary stations, in par- ticular over 30 continuous recording 3-component 2 Hz stations. Refraction seismics from offshore to onshore was further implemented by short-duration deployments of vertical component lightweight instruments with short recording capacity. A teleseis- mic recording effort with temporary stations, tested in the previous year concentrated on a line through the NAF East of Izmit 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rembold, Randy Kai; Hart, Darren M.; Harris, James Mark

Sandia National Laboratories has tested, evaluated and reported on the Geotech Smart24 data acquisition system with active Fortezza crypto card data signing and authentication in SAND2008-. One test, Input Terminated Noise, allows us to characterize the self-noise of the Smart24 system. By computing the power spectral density (PSD) of the input terminated noise time series data set and correcting for the instrument response of different seismometers, the resulting spectrum can be compared to the USGS new low noise model (NLNM) of Peterson (1996), and determine the ability of the matched system of seismometer and Smart24 to be quiet enough formore » any general deployment location. Four seismometer models were evaluated: the Streckeisen STS2-Low and High Gain, Guralp CMG3T and Geotech GS13 models. Each has a unique pass-band as defined by the frequency band of the instrument corrected noise spectrum that falls below the new low-noise model.« less

Development of a Lunar Borehole Seismometer

NASA Astrophysics Data System (ADS)

Passmore, P. R.; Siegler, M.; Malin, P. E.; Passmore, K.; Zacny, K.; Avenson, B.; Weber, R. C.; Schmerr, N. C.; Nagihara, S.

2017-12-01

Nearly all seismic stations on Earth are buried below the ground. Burial provides controlled temperatures and greater seismic coupling at little cost. This is also true on the Moon and other planetary bodies. Burial of a seismometer under just 1 meter of lunar regolith would provide an isothermal environment and potentially reduce signal scattering noise by an order of magnitude. Here we explain how we will use an existing NASA SBIR and PIDDP funded subsurface heat flow probe deployment system to bury a miniaturized, broadband, optical seismometer 1 meter below the lunar surface. The system is sensitive, low mass and low power. We believe this system offers a compelling architecture for NASA's future seismic exploration of the solar system. We will report on a prototype 3-axis, broadband seismometer package that has been tested under low pressure conditions in lunar-regolith simulant. The deployment mechanism reaches 1m depth in less than 25 seconds. Our designed and tested system: 1) Would be deployed at least 1m below the lunar surface to achieve isothermal conditions without thermal shielding or heaters, increase seismic coupling, and decrease noise. 2) Is small (our prototype probe is a cylinder 50mm in diameter, 36cm long including electronics, potentially as small as 10 cm with sensors only). 3) Is low-mass (each sensor is 0.1 kg, so an extra redundancy 4-component seismograph plus 1.5 kg borehole sonde and recorder weighs less than 2 kg and is feasibly smaller with miniaturized electronics). 4) Is low-power (our complete 3-sensor borehole seismographic system's power consumption is about half a Watt, or 7% of Apollo's 7.1 W average and 30% of the InSight SEIS's 1.5W winter-time heating system). 5) Is broadband and highly sensitive (the "off the shelf" sensors have a wide passband: 0.005-1000 Hz - and high dynamic range of 183 dB (or about 10-9g Hz-1/2, with hopes for simple modifications to be at least an order of magnitude better). Burial also aids the sensitivity, by decreasing scattered noise through the upper, extremely low density lunar regolith.

Installation of seafloor cabled seismic and tsunami observation system developed by using ICT

NASA Astrophysics Data System (ADS)

Shinohara, M.

2016-12-01

A seafloor cabled system is useful for study of earth science and disaster mitigation, because real-time and long-term observation can be performed. Therefore seafloor cabled systems with seismometers and tsunami-meters have been used over the past 25 years around Japan. Because increase of a number of sensors is needed, a new system with low costs for production, deployment and operation is expected. In addition, the new system should have sufficient for flexibility of measurements after installation. To achieve these demands, we started development of a new system using Information and Communication Technologies (ICT) for data transmission and system control. The new system can be made compact since software processes various measurements. Reliability of the system is kept by using redundant system which is easily constructed using the ICT. The first system based on this concept was developed as Ocean Bottom Cabled Seismometer (OBCS) system and deployed in Japan Sea. Development of the second system started from 2012. The Ocean Bottom Cabled Seismometer and tsunami-meter (OBCST) system has both seismometers and tsunami-meters. Each observation node has an CPU and FPGAs. The OBCST system uses standard TCP/IP protocol with a speed of 1 Gbps for data transmission, system control and monitoring. IEEE-1588 (PTP) is implemented to synchronize a real-time clock, and accuracy is less than 300 ns. We developed two types of observation node. One equips a pressure gauge as tsunami sensor, and another has an external port for additional observation sensor using PoE. Deployment of the OBCST system was carried out in September 2015 by using a commercial telecommunication cable ship. The noise levels at the OBCST system are comparable to those at the existing cabled system off Sanriku. It is found that the noise levels at the OBCST system are low at frequencies greater than 2 Hz and smaller than 0.1 Hz. This level of ambient seismic noise is close to a typical system noise. From the pressure data, pressure gauge has a resolution of less than 1 hPa, which corresponds to a change of water height of less than 1 cm, and data from all the pressure gauges are consistent.

Lopez Island Ocean Bottom Seismometer Intercomparison Experiment.

DTIC Science & Technology

1980-10-01

dividing the, record into N 4-see-long records (where N-30) and averaging4 - ].- ~ I I I I I I r r I I I I I I I I SEC - II L L I I L I I I I I I 80 1...about 1 m (Sutton et al., 1980). The OBS’s were located within tens of meters ot eacti other in deep waiter . The hydrophones are well correlated, showing...1 - 21)2 ) (5) where D is a damping constant which is the actual damping constant divided by the critical damping constant C I/cc. Lvsmer’s analog

Analysis of the Seismicity Associated to the Subduction of the Rivera Plate using OBS and Onland Stations.

NASA Astrophysics Data System (ADS)

Nuñez-Cornu, F. J.; Barba, D. C., Sr.; Danobeitia, J.; Bandy, W. L.; Zamora-Camacho, A.; Marquez-Ramirez, V. H.; Ambros, M.; Gomez, A.; Sandoval, J. M.; Mortera-Gutierrez, C. A.

2016-12-01

The second stage of TsuJal Project includes the study of passive seismic activity in the region of the plate Rivera and Jalisco block by anchoring OBS and densifying the network of seismic stations on land for at least four months. This stage began in April 2016 with the deployment of 25 Obsidian stations with sensor Le-3D MkIII from the northern part of Nayarit state to the south of Colima state, including the Marias Islands. This temporal seismic network complements the Jalisco Seismic Network (RESAJ) for a total of 50 stations. Offshore, ten OBS type LCHEAPO 2000 with 4 channel (3 seismic short period and 1 pressure) were deployed, in the period from 19 to 30 April 2016 using the BO El Puma from UNAM. The OBS were deployed in an array from the Marias Islands to offcoast of the border of Colima and Michoacan states. On May 4, an earthquake with Ml = 4.2 took place in the contact area of the Rivera Plate, Cocos Plate and the Middle America Trench, subsequently occurred a seismic swarm with over 200 earthquakes until May 16, including an earthquake with Ml = 5.0 on May 7. A second swarm took place between May 28 and Jun 4 including an earthquake with Ml = 4.8 on Jun 1. An analysis of the quality of different location methods is presented: automatic preliminary RESAJ location using Antelope; location with revised RESAJ phases in Antelope; relocation of RESAJ data with hypo and a regional velocity model; relocation of RESAJ data with hypo adding data from the temporal seismic network stations; and finally the relocation adding the data from the OBS network. Moreover, the tectonic implications of these earthquakes are discussed.

Preliminary results of the Source China Sea passive source OBS array experiment

NASA Astrophysics Data System (ADS)

Yang, T.; Liu, C.; Pei, Y.; Xia, S.

2013-12-01

The Scarborough, or Huangyan, Seamount chain in South China Sea (SCS) represents an extreme case of the global mid-ocean ridge system where the magmatism continues for many million years after the cessation of spreading. To understand this unique process, the South China Sea Deep (SCSD) program funded an experiment deploying a passive source OBS array to image the lithospheric structure beneath the extinct ridge. In April 2012, 18 passive source OBSs, including 15 Guralp CMG-40T OBS and 3 I-4C OBS, were deployed around the Huangyan Island for one year. 11 OBSs were successfully recovered this April, and their data are being processed. Here we present some preliminary results from analyses of this dataset, including the general quality of three-component seismograms, characteristics of seafloor ambient noise spectra, determining the OBS orientation from the Rayleigh wave polarization, and the dispersion analysis of Rayleigh waves. We found that, for most stations, seismograms from teleseismic, regional and local events are generally good with the horizontal records being comparable with vertical component. The noise levels in these seafloor stations are much higher than land-based stations, especially in shorter periods, likely suggesting the direct and stronger impact from the tempestuous SCS. Applications of more sophisticated seismic techniques such as surface wave tomography, seismic anisotropy, receiver function and ambient noise cross-correlation are underway. In addition to the low recovery rate, there are other lessons learned from this experiment. For example, at least two stations have detectable timing problems; Airgun shots should have been used to constrain the timings and orientations in both deployment and recovery. It is still challenging and costly to carry out long-term passive source seismic observations in deep sea.

A New Design of Seismic Stations Deployed in South Tyrol

NASA Astrophysics Data System (ADS)

Melichar, P.; Horn, N.

2007-05-01

When designing the seismic network in South Tyrol, the seismic service of Austria and the Civil defense in South Tyrol combined more that 10 years experience in running seismic networks and private communication systems. In recent years the high data return rate of > 99% and network uptime of > 99.% is achieved by the combination of high quality station design and equipment, and the use of the Antelope data acquisition and processing software which comes with suite of network monitoring & alerting tools including Nagios, etc. The new Data Center is located in city of Bolzano and is connected to the other Data Centers in Austria, Switzerland, and Italy for data back up purposes. Each Data Center uses also redundant communication system if the primary system fails. When designing the South Tyrol network, new improvements were made in seismometer installations, grounding, lighting protection and data communications in order to improve quality of data recorded as well as network up-time, and data return. The new 12 stations are equipped with 6 Channels Q330+PB14f connected to STS2 + EpiSensor sensor. One of the key achievements was made in the grounding concept for the whole seismic station - and aluminum boxes were introduced which delivered Faraday cage isolation. Lightning protection devices are used for the equipment inside the aluminum housing where seismometer and data logger are housed. For the seismometer cables a special shielding was introduced. The broadband seismometer and strong-motion sensor are placed on a thick glass plate and therefore isolated from the ground. The precise seismometer orientation was done by a special groove on the glass plate and in case of a strong earthquake; the seismometer is tide up to the base plate. Temperature stability was achieved by styrofoam sheets inside the seismometer aluminum protection box.

The Seismic Broad Band Western Mediterranean (wm) Network and the Obs Fomar Pool: Current state and Obs activities.

NASA Astrophysics Data System (ADS)

Pazos, Antonio; Davila, Jose Martin; Buforn, Elisa; Bezzeghoud, Mourad; Harnafi, Mimoun; Mattesini, Mauricio; Caldeira, Bento; Hanka, Winfried; El Moudnib, Lahcen; Strollo, Angelo; Roca, Antoni; Lopez de Mesa, Mireya; Dahm, Torsten; Cabieces, Roberto

2016-04-01

The Western Mediterranean (WM) seismic network started in 1996 as an initiative of the Royal Spanish Navy Observatory (ROA) and the Universidad Complutense de Madrid (UCM), with the collaboration of the GeoForschungsZentrum (GFZ) of Potsdam. A first broad band seismic station (SFUC) was installed close to Cádiz (South Spain). Since then, additional stations have been installed in the Ibero-Moghrebian region. In 2005, the "WM" code was assigned by the FDSN and new partners were jointed: Evora University (UEVO, Portugal), the Scientifique Institute of Rabat (ISRABAT, Morocco), and GFZ. Now days, the WM network is composed by 15 BB stations, all of them with Streckaisen STS-2 or STS-2.5 sensors, Quanterra or Earthdata digitizers and SeiscomP. Most them have co-installed a permanent geodetic GPS stations, and some them also have an accelerometer. There are 10 stations deployed in Spanish territory (5 in the Iberian peninsula, 1 in Balearic islands and 4 in North Africa Spanish places) with VSAT or Internet communications, 2 in Portugal (one of them without real time), and 3 in Morocco (2 VSAT and 1 ADSL). Additionally, 2 more stations (one in South Spain and one in Morocco) will be installed along this year. Additionally ROA has deployed a permanent real time VBB (CMG-3T: 360s) station at the Alboran Island. Due to the fact that part of the seismic activity is located at marine areas, and also because of the poor geographic azimuthal coverage at some zones provided by the land stations (specially in the SW of the San Vicente Cape area), ROA and UCM have acquired six broad band "LOBSTERN" OBS, manufactured by KUM (Kiel, Germany), conforming the OBS FOMAR pool. Three of them with CMG-40T sensor and the other with Trillium 120. These OBS were deployed along the Gibraltar strait since January to November 2014 to study the microseismicity in the Gibraltar strait area. In September 2015 FOMAR network has been deployed in SW of the San Vicente Cape for 8 months as a part of ALERTES-RIM project. In this work the current state and future plans of the WM network, the results of the Gibraltar strait campaign and San Vicente Cape OBS experiment are shown.

Mantle-crust interaction at the Blanco Ridge segment of the Blanco Transform Fault Zone: Results from the Blanco Transform Fault OBS Experiment

NASA Astrophysics Data System (ADS)

Kuna, V. M.; Nabelek, J.; Braunmiller, J.

2016-12-01

We present results of the Blanco Transform OBS Experiment, which consists of the deployment of 55 three-component broadband and short-period ocean bottom seismometers in the vicinity of the Blanco Fault Zone for the period between September 2012 and October 2013. Our research concentrates on the Blanco Ridge, a purely transform segment of the Blanco Fault Zone, that spans over 130 km between the Cascadia and the Gorda pull-apart depressions. Almost 3,000 well-constrained earthquakes were detected and located along the Blanco Ridge by an automatic procedure (using BRTT Antelope) and relocated using a relative location algorithm (hypoDD). The catalog magnitude of completeness is M=2.2 with an overall b value of 1. Earthquakes extend from 0 km to 20 km depth, but cluster predominantly at two depth levels: in the crust (5-7 km) and in the uppermost mantle (12-17 km). Statistical analysis reveals striking differences between crustal and mantle seismicity. The temporal distribution of crustal events follows common patterns given by Omori's law, while most mantle seismicity occurs in spatially tight sequences of unusually short durations lasting 30 minutes or less. These sequences cannot be described by known empirical laws. Moreover, we observe increased seismic activity in the uppermost mantle about 30 days before the largest (M=5.4) earthquake. Two mantle sequences occurred in a small area of 3x3 km about 4 and 2 weeks before the M=5.4 event. In the week leading up to the M=5.4 event we observe a significant downward migration of crustal seismicity, which results in the subsequent nucleation of the main event at the base of the crust. We hypothesize that the highly localized uppermost mantle seismicity is triggered by aseismic slow-slip of the surrounding ductile mantle. We also suggest that the mantle slip loads the crust eventually resulting in relatively large crustal earthquakes.

Progress on the NEPTUNE Canada Seismograph Network

NASA Astrophysics Data System (ADS)

Rogers, G. C.; Meldrum, R. D.; Heesemann, M.; Mulder, T. L.; Brillon, C. D.; Cassidy, J. F.

2012-12-01

NEPTUNE Canada is the world's first deep-sea regional multi-disciplinary scientific cabled ocean observatory. In the fall of 2007 an 800 kilometer ring of powered fiber optic cable was laid on the seafloor over the northern part of the Juan de Fuca plate and connected to a shore facility near Port Alberni on Vancouver Island. In September 2009, three broadband OBS packages were deployed in the form of a large triangle with apexes at mid plate near ODP 1027 (water depth of 2654m) and two sites on the continental slope, near ODP 889 (1256m) and Barkley Canyon (396m). The broadband systems comprise a broadband seismometer and strong motion accelerometer in a spherical titanium case surficially buried in a caisson backfilled with glass beads. Noise levels observed are as expected with the spectra being similar to, or quieter than, coastal seismograph stations in approximately the 10 to 20 second period range. The OBS's have higher noise levels at longer periods where ocean swells and the resultant infragravity waves dominate the noise spectra, and in the 1-10 Hz bandwidth typically used for locating local earthquakes. The shallowest site at Barkley Canyon has the highest noise levels. A small array, about 6 km in maximum dimension, is under construction on the Endeavour segment of the Juan de Fuca Ridge to record earthquake activity in the vicinity of the many NEPTUNE Canada multi-disciplinary ridge experiments. Two short period instruments were installed there in 2010. A broadband instrument and two additional short period instruments are planned to complete the initial ridge array. Even though the NEPTUNE Canada seismograph network is not yet complete, measured by the use of its data, it is a success already. The data are routinely used along with data from land seismographs of the Canadian National Seismograph Network for locating earthquakes in the region. However, the smallest seismic arrivals picked on the land stations cannot be routinely picked on the OBS instruments due to the higher noise levels. Real-time data are also ingested by NOAA tsunami warning centers and researchers have accessed archived data to do such diverse things as track baleen whales, carry out receiver function analyses, and study microseismic noise. NEPTUNE Canada seismic data is freely available from IRIS.

Installation of seafloor cabled seismic and tsunami observation system developed by using ICT

NASA Astrophysics Data System (ADS)

Shinohara, Masanao; Yamada, Tomoaki; Sakai, Shin'ichi; Shiobara, Hajime; Kanazawa, Toshihiko

2017-04-01

A seafloor cabled system is useful for study of earth science and disaster mitigation, because real-time and long-term observation can be performed. Therefore seafloor cabled systems with seismometers and tsunami-meters have been used over the past 25 years around Japan. Because increase of a number of sensors is needed, a new system with low costs for production, deployment and operation is expected. In addition, the new system should have sufficient for flexibility of measurements after installation. To achieve these demands, we started development of a new system using Information and Communication Technologies (ICT) for data transmission and system control. The new system can be made compact since software processes various measurements. Reliability of the system is kept by using redundant system which is easily constructed using the ICT. The first system based on this concept was developed as Ocean Bottom Cabled Seismometer (OBCS) system and deployed in Japan Sea. Development of the second system started from 2012. The Ocean Bottom Cabled Seismometer and Tsunami-meter (OBCST) system has both seismometers and tsunami-meters. Each observation node has a CPU and FPGAs. The OBCST system uses standard TCP/IP protocol with a speed of 1 Gbps for data transmission, system control and monitoring. IEEE-1588 (PTP) is implemented to synchronize a real-time clock, and accuracy is less than 300 ns. We developed two types of observation node. One equips a pressure gauge as tsunami sensor, and another has an external port for additional observation sensor using PoE. Deployment of the OBCST system was carried out in September 2015 by using a commercial telecommunication cable ship. The noise levels at the OBCST system are comparable to those at the existing cabled system off Sanriku. It is found that the noise levels at the OBCST system are low at frequencies greater than 2 Hz and smaller than 0.1 Hz. This level of ambient seismic noise is close to a typical system noise. From the pressure data, pressure gauge has a resolution of less than 1 hPa, which corresponds to a change of water height of less than 1 cm, and data from all the pressure gauges are consistent. From the deployment, the system has been collecting data on seafloor until the present. Tsunami waves on November 22nd, 2016, which were generated by an earthquake with magnitude of 7.4 off Fukushima were clearly observed by all tsunami sensors in the system.

Seismicity in the Wake of the April 2016 Pedernales Earthquake

NASA Astrophysics Data System (ADS)

Meltzer, A.; Beck, S. L.; Ruiz, M. C.; Hernandez, S.; Alvarado, A. P.; Regnier, M. M.; Rietbrock, A.; Font, Y.; Charvis, P.; Yepes, H. A.; Lynner, C.; Porritt, R. W.

2016-12-01

On April 16th 2016 a Mw7.8 earthquake struck along the Colombia-Ecuador trench near Pedernales, Ecuador. The epicentral region lies just north of the intersection of the Carnegie Ridge with the subduction zone where the orientation of the trench shifts from N20°E to N32°E. This portion of the subduction zone has ruptured on decadal time scales; Mw7.8 (1942), Mw 7.7 (1958), and Mw 8.8 (1906). The rupture zone of the 2016 Pedernales earthquake falls within the rupture area of the 1906 event and appears to overlap with the previous 1942 event. In the wake of the earthquake an international response coordinated by the Instituto Geofisico EPN in Quito deployed accelerometers, seismometers, OBS, and GPS receivers to record aftershocks and post-seismic deformation. These data provide the opportunity to examine the persistence of asperities for large to great earthquakes over multiple seismic cycles, the role of asperities in promoting or inhibiting rupture propagation, and the relationship between locked and creeping parts of the subduction interface. Onland, a dense array of 64 broadband and intermediate period seismometers cover the 2016 rupture zone, extending north to the section that ruptured in 1958 and covers the contiguous area that ruptured in 1906. The US portion of the response supported by the NSF includes 19 broadband seismic stations to record aftershocks for a year, an eGPS survey, and five cGPS stations to enhance the existing network in Ecuador. Data from the NSF supported stations are open access. We examine the distribution of seismicity from the aftershock deployment in relationship to the 1942, 1958, and 1906 ruptures. Preliminary locations from the IG-EPN aftershock catalog outline the rupture zone and initially exhibited an abrupt termination to the north at 1°N. Along this northern boundary a series of aftershocks that took place over a period of several hours along a very linear trend culminated in one of several ≥Mw 6.0 aftershocks. To the south, a significant cluster of events is observed 100 km south of the area that ruptured in the mainshock. This area lies south of an area of low coupling observed in GPS data suggesting that stress is being transmitted across a zone that is freely slipping. In July a series of events occurred north of the rupture zone close to the edge of the segment that ruptured in 1958.

Trillium Horizon, A Small Portable Observatory Grade Seismometer For Direct Bury And Vault Use

NASA Astrophysics Data System (ADS)

Moores, A.; Parker, T.; Bainbridge, G.

2017-12-01

As of August 2017 almost 5 years of data have been collected from broadband seismic sensors designed for direct burial applications. These first posthole instruments have been deployed in a wide range of extremely challenging environments such as dynamic ice and snow environments, extreme wet and dry conditions in soils of high clay content, and steep creeping terrain. In all use cases the direct burial approach has consistently provided high quality data when compared to shallow vault installations. In this presentation we extract and analyze operational performance data, including tilt information from mass position time series recorded at direct burial installations and at temporary shallow vault deployments. This data shows that while higher tilt tolerance is required for data quality outcome certainty in some installations, the majority of installations can be addressed by a smaller instrument with a narrower tilt range hence reducing size and cost. The lessons learned from this real world field data have guided the development of a new smaller, less expensive instrument, Trillium Horizon.Based on this analysis and and user feedback from many direct burial deployments, the Trillium Horizon seismometer has been developed as a simple versatile instrument to span the majority of deployment scenarios and specific use cases including shallow direct bury deployments, traditional piers, and problematic wet vault installs. With its small size, robust waterproof case and connector, +/-1.5° tilt range, dual-purpose cable, and accessories for both posthole and vault installation, Trillium Horizon is optimized for usability as well as performance.

Field measurement of penetrator seismic coupling in sediments and volcanic rocks

NASA Technical Reports Server (NTRS)

Nakamura, Y.; Latham, G. V.; Frohlich, C.

1979-01-01

Field experiments were conducted to determine experimentally how well a seismometer installed using a penetrator would be coupled to the ground. A dry lake bed and a lava bed were chosen as test sites to represent geological environments of two widely different material properties. At each site, two half-scale penetrators were fired into the ground, a three-component geophone assembly was mounted to the aft end of each penetrator, and dummy penetrators were fired at various distances to generate seismic signals. The recorded signals were digitized, and cross-spectral analyses were performed to compare the observed signals in terms of power spectral density ratio, coherence and phase difference. The analyses indicate that seismometers deployed by penetrators will be as well coupled to the ground as are seismometers installed by conventional methods for the frequency range of interest in earthquake seismology, although some minor differences were observed at frequencies near the upper limit of the frequency band.

Mud volcano monitoring and seismic events along the North Anatolian Fault (Sea of Marmara)

NASA Astrophysics Data System (ADS)

Javad Fallahi, Mohammad; Lupi, Matteo; Mazzini, Adriano; Polonia, Alina; D'Alessandro, Antonino; D'Anna, Giuseppe; Gasperini, Luca

2017-04-01

The Sea of Marmara, a pull-apart basin formed along the northern strand of the North Anatolian Fault (NAF) system, is considered a seismic gap, that will be filled in the next decades by a large magnitude (M>7) earthquake, close to the Istanbul Metropolitan area (12 million inhabitants). For this reason, several marine geological and geophysical studies have been carried out in this region, starting from the destructive 1999 Mw 7.4 Izmit earthquake, to gather information relative to seismogenic potential of major fault strands. Together with these studies, in the frame of EC projects (i.e., MarmESONET and Marsite, among others), an intensive program of long-term monitoring of seismogenic faults was carried out using seafloor observatories deployed during several expeditions led by Italian, French and Turkish groups. These expeditions included MARM2013, on board of the R/V Urania, of the Italian CNR, when four ocean bottom seismometers (OBS) were deployed in the central part of the Sea of Marmara, at depths between 550 and 1000 m. One of the main aims of the experiment was to assess the long-term seismic activity along an active segment of the NAF, which connects the central and the western basins (depocenters), where the principal deformation zone appears relatively narrow and almost purely strike-slip. The present study shows the results of processing and analysis of continuous data records from these OBS stations during 50 days. We were able to detect seismic signal produced by an active mud volcano located close to the NAF trace, from about 3 to 6 km of distance from the OBS stations. Additionally, we captured the May 24, 2014, Mw 6.9 strike-slip earthquake occurred in the northern Aegean Sea between Greece and Turkey, which caused serious damage on the Turkish island of Imbros and the cities of Edirne and Çanakkale, as well as on the Greek island of Lemnos. The earthquake nucleated on the westward continuation of the NAF system in the NE Aegean Sea, and was felt in Bulgaria and southern Romania. Several aftershocks followed the main shock, the strongest measuring 5.3 of magnitude. To verify the effects of this external forcing on the activity of the submarine mud volcano in Marmara, we calculated the root-mean-square (RMS) and standard deviation (STD) on three-minute waveform segments in a period from 2014.04.11 to 2014.05.31 in the 10-25 Hz frequency band. In addition, we also calculated auto- and cross-correlation of seismic ambient noise in the same time-period and frequency range to assess the variations of waveform coherency prior to the earthquake. Preliminary results show periodic changes of RMS and STD amplitudes, which may result from the effects of tides, but no short- or long-term precursory signs of the earthquake detected by our approach.

Engaging High School Science Teachers in Field-Based Seismology Research: Opportunities and Challenges

NASA Astrophysics Data System (ADS)

Long, M. D.

2015-12-01

Research experiences for secondary school science teachers have been shown to improve their students' test scores, and there is a substantial body of literature about the effectiveness of RET (Research Experience for Teachers) or SWEPT (Scientific Work Experience Programs for Teachers) programs. RET programs enjoy substantial support, and several opportunities for science teachers to engage in research currently exist. However, there are barriers to teacher participation in research projects; for example, laboratory-based projects can be time consuming and require extensive training before a participant can meaningfully engage in scientific inquiry. Field-based projects can be an effective avenue for involving teachers in research; at its best, earth science field work is a fun, highly immersive experience that meaningfully contributes to scientific research projects, and can provide a payoff that is out of proportion to a relatively small time commitment. In particular, broadband seismology deployments provide an excellent opportunity to provide teachers with field-based research experience. Such deployments are labor-intensive and require large teams, with field tasks that vary from digging holes and pouring concrete to constructing and configuring electronics systems and leveling and orienting seismometers. A recently established pilot program, known as FEST (Field Experiences for Science Teachers) is experimenting with providing one week of summer field experience for high school earth science teachers in Connecticut. Here I report on results and challenges from the first year of the program, which is funded by the NSF-CAREER program and is being run in conjunction with a temporary deployment of 15 seismometers in Connecticut, known as SEISConn (Seismic Experiment for Imaging Structure beneath Connecticut). A small group of teachers participated in a week of field work in August 2015 to deploy seismometers in northern CT; this experience followed a visit of the PI to the classroom of one of the teacher participants during spring 2015 to give a series of talks on Connecticut earthquakes and geology. This presentation will focus on the challenges and opportunities of running small, PI-driven, field-based RET programs.

MUG-OBS - Multiparameter Geophysical Ocean Bottom System : a new instrumental approach to monitor earthquakes.

NASA Astrophysics Data System (ADS)

hello, yann; Charvis, Philippe; Yegikyan, Manuk; verfaillie, Romain; Rivet, Diane

2016-04-01

Real time monitoring of seismic activity is a major issue for early warning of earthquakes and tsunamis. It can be done using regional scale wired nodes, such as Neptune in Canada and in the U.S, or DONET in Japan. Another approach to monitor seismic activity at sea is to deploying repeatedly OBS array like during the amphibious Cascadia Initiative (four time 1-year deployments), the Japanese Pacific Array (broadband OBSs "ocean-bottom broadband dispersion survey" with 2-years autonomy), the Obsismer program in the French Lesser Antilles (eight time 6-months deployments) and the Osisec program in Ecuador (four time 6-months deployments). These autonomous OBSs are self-recovered or recovered using an ROV. These systems are costly including ship time, and require to recover the OBS before to start working on data. Among the most recent alternative we developed a 3/4 years autonomy ocean bottom system with 9 channels (?) allowing the acquisition of different seismic or environmental parameters. MUG-OBS is a free falling instrument rated down to 6000 m. The installation of the sensor is monitored by acoustic commands from the surface and a health bulletin with data checking is recovered by acoustic during the installation. The major innovation is that it is possible to recover the data any time on demand (regularly every 6-months or after a crisis) using one of the 6 data-shuttles released from the surface by acoustic command using a one day fast cruise boat of opportunity. Since sensors stayed at the same location for 3 years, it is a perfect tool to monitor large seismic events, background seismic activity and aftershock distribution. Clock, drift measurement and GPS localization is automatic when the shuttle reaches the surface. For remote areas, shuttles released automatically and a seismic events bulletin is transmitted. Selected data can be recovered by two-way Iridium satellite communication. After a period of 3 years the main station is self-recovered by acoustic.

Sensor Emplacement Techniques and Seismic Noise Analysis for USArray Transportable Array Seismic Stations

NASA Astrophysics Data System (ADS)

Frassetto, A.; Busby, R. W.; Hafner, K.; Woodward, R.; Sauter, A.

2013-12-01

In preparation for the upcoming deployment of EarthScope's USArray Transportable Array (TA) in Alaska, the National Science Foundation (NSF) has supported exploratory work on seismic station design, sensor emplacement, and communication concepts appropriate for this challenging high-latitude environment. IRIS has installed several experimental stations to evaluate different sensor emplacement schemes both in Alaska and in the lower-48 of the U.S. The goal of these tests is to maintain or enhance a station's noise performance while minimizing its footprint and the weight of the equipment, materials, and overall expense required for its construction. Motivating this approach are recent developments in posthole broadband seismometer design and the unique conditions for operating in Alaska, where there are few roads, cellular communications are scarce, most areas are only accessible by small plane or helicopter, and permafrost underlies much of the state. We will review the methods used for directly emplacing broadband seismometers in comparison to the current methods used for the lower-48 TA. These new methods primarily focus on using a portable drill to make a bored hole three to five meters, beneath the active layer of the permafrost, or by coring 1-2 meters deep into surface bedrock. Both methods are logistically effective in preliminary trials. Subsequent station performance has been assessed quantitatively using probability density functions summed from power spectral density estimates. These are calculated for the continuous time series of seismic data recorded for each channel of the seismometer. There are five test stations currently operating in Alaska. One was deployed in August 2011 and the remaining four in October 2012. Our results show that the performance of seismometers in Alaska with auger-hole or core-hole installations can sometimes exceed that of the quietest TA stations in the lower-48, particularly horizontal components at long periods. A comparison of the performance of the various installations is discussed.

Tethered Aerostat Effects on Nearby Seismometers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowman, Daniel

This report assesses seismic interference generated by a tethered aerostat. The study was motivated by a planned aerostat deployment within the footprint of the Dry Alluvium Geology seismic network. No evidence was found for seismic interference generated by the aerostat, and thus the e ects on the Dry Alluvium Geology sensors will be negligible.

Apollo 12, A New Vista for Lunar Science.

ERIC Educational Resources Information Center

National Aeronautics and Space Administration, Washington, DC.

Man's second lunar landing, Apollo 12, provided a wealth of scientific information about the moon. The deployment of the magnetometer, seismometer, and ionosphere detector, and other activities on the lunar surface are described. A number of color photographs show the astronauts setting up equipment on the moon as well as close-ups of the lunar…

Draft Environmental Impact Statement. MX Deployment Area Selection and Land Withdrawal/Acquisition DEIS. Volume IV. Part II. Environmental Consequences to the Study Regions and Operating Base Vicinities.

DTIC Science & Technology

1980-12-01

desert tortoise distribution at Coyote Spring OB and vicinity. 4-179 4.3.1.9-3 Utah Prairie Dog distribution and Proposed Action conceptual project...layout. 4-185 4.3.1.9-4 Distribution of Utah prairie dog in the vicinity of the Milford OB. 4-187 4.3.1.9-5 Distribution of Utah prairie dog in the...Coyote Spring. 4-180 4.3.1.9-2 Potential impact to the Utah prairie dog around operating bases (OBs) for the Proposed Action and Alternatives 1-8. 4-188

Shear wave splitting observations across the Juan de Fuca plate system: Ridge- to-trench constraints on mantle flow from 2 years of Cascadia Initiative OBS data

NASA Astrophysics Data System (ADS)

Bodmer, M.; Toomey, D. R.; Hooft, E. E. E.

2014-12-01

We present SKS splitting measurements for the first two years of data collected by the Cascadia Initiative (CI) amphibious array. Our analysis includes observations from over 100 ocean bottom seismometers (OBS), as well as 31 onshore stations, and spans both the Juan de Fuca and Gorda plates. The CI dataset is unique in that it includes several regions that can distinctly influence anisotropic fabric development such as: the upwelling mantle beneath the Juan de Fuca and Gorda ridges, the young evolving oceanic lithosphere of the plate interior, the Blanco transform fault, and the Cascadia subduction zone. For the first time, we are able to analyze these regions with a single dataset, and using a common methodology. Splitting measurements are routinely done on land sites, but have been completed on relatively few OBS stations. This is largely due to the low signal to noise present in OBS data, which can obscure the splitting results. To address that nearly all the OBS data exceeds the global high noise limit at the frequencies used for splitting, we implement a rigorous quality control scheme. Our method specifically takes into account the response of common splitting methods to high noise data and addresses known issues such as cycle skipping, false minima, low transverse energy, and near-null measurements. Individual measurements are filtered at 0.03-0.1 Hz, manually checked for quality, and stacked. Preliminary results show trench perpendicular onshore measurements consistent with previous studies. Oceanic measurements in the plate interior show a coherent fast axis roughly aligned with absolute plate motion. Several measurements near the ridge and trench appear to be rotated in the ridge and trench parallel directions. Continuing work will integrate splitting measurements from the final two years of the CI with these findings, which will be used to characterize the ridge-to-trench mantle flow across the Juan de Fuca plate system.

Travel time seismic tomography on Reykjanes, SW Iceland

NASA Astrophysics Data System (ADS)

Jousset, Philippe; Ágústsson, Kristjan; Blanck, Hanna; Metz, Malte; Franke, Steven; Pàll Hersir, Gylfi; Bruhn, David; Flovenz, Ólafur; Friðleifsson, Guðmundur

2017-04-01

We present updated tomographic results obtained using seismic data recorded around geothermal reservoirs located both on-land Reykjanes, SW-Iceland and offshore along Reykjanes Ridge. We gathered records from a network of 234 seismic stations (including 24 Ocean Bottom Seismometers) deployed between April 2014 and August 2015. In order to determine the orientation of the OBS stations, we used Rayleigh waves planar particle motions from large magnitude earthquakes. This method proved suitable using the on-land stations: orientations determined using this method with the orientations measured using a giro-compass agreed. We focus on the 3D velocity images using local earthquakes to perform travel time tomography. The processing includes first arrival picking of P- and S- phases using an automatic detection and picking technique based on Akaike Information Criteria. We locate earthquakes by using a non-linear localization technique, as a priori information for deriving a 1D velocity model. We then computed 3D velocity model by joint inversion of each earthquake's location and velocity lateral anomalies with respect to the 1D model. Our models confirms previous models obtained in the area, with enhanced details. In a second step, we performed inversion of the Vp/Vs ratio. Results indicate a low Vp/Vs ratio anomaly at depth suggesting the absence of large magmatic body under Reykjanes, unlike results obtained at other geothermal field, sucha as Krafla and Hengill. We discuss implications of those results in the light of recent IDDP drilling in Reykjanes.

Dual-vergence structure from multiple migration of widely spaced OBSs

NASA Astrophysics Data System (ADS)

Yelisetti, Subbarao; Spence, George D.; Scherwath, Martin; Riedel, Michael; Klaeschen, Dirk

2017-10-01

The detailed structure of the northern Cascadia basin and frontal ridge region was obtained using data from several widely spaced ocean bottom seismometers (OBSs). Mirror imaging was used in which the downgoing multiples (mirror signal) are migrated as they provide information about a much larger area than imaging with primary signal alone. Specifically, Kirchhoff time migration was applied to hydrophone and vertical geophone data. Our results indicate remarkable structures that were not observed on the northern Cascadia margin in previous single-channel or multi-channel seismic (MCS) data. Results show that, in these water depths (2.0-2.5 km), an OBS can image up to 5 km on either side of its position on the seafloor and hence an OBS spacing of 5 km is sufficient to provide a two-fold migration stack. Results also show the top of the igneous oceanic crust at 5-6 km beneath the seafloor using only a small airgun source (120 in.3). Specifically, OBS migration results clearly show the continuity of reflectors which enabled the identification of frontal thrusts and a main thrust fault. These faults indicate, for the first time on this margin, the presence of a dual-vergence structure. These kinds of structures have so far been observed in < 0.5% of modern convergent margins and could be related to horizontal compression associated with subduction and low basal shear stress resulting from over-pressure. Reanalysis of previous MCS data from this region augmented the OBS migration results and further suggests that the vergence switches from seaward to landward around central Vancouver Island. Furthermore, fault geometry analyses indicate that the total amount of shortening accommodated due to faulting and folding is about 3 km, which suggest that thrusting would have started at least ∼ 65 ky ago.

An integrated approach to the seismic activity and structure of the central Lesser Antilles subduction megathrust seismogenic zone

NASA Astrophysics Data System (ADS)

Hirn, Alfred; Laigle, Mireille; Charvis, Philippe; Flueh, Ernst; Gallart, Josep; Kissling, Edi; Lebrun, Jean-Frederic; Nicolich, Rinaldo; Sachpazi, Maria

2010-05-01

In order to increase the understanding of plate boundaries that show currently low seismic activity, as was the Sumatra-Andaman subduction before the major earthquake in 2004, a cluster of surveys and cruises has been carried out in 2007 and coordinated under the European Union THALES WAS RIGHT project on the Lesser Antilles subduction zone of the Carribean-America plate boundary. A segment of the corresponding transform boundary just tragically ruptured in the 2010 January 12, Haïti earthquake. This cluster is composed by the German cruise TRAIL with the vessel F/S M. A. MERIAN, the French cruise SISMANTILLES II with the IFREMER vessel N/O ATALANTE), and French cruise OBSANTILLES with the IRD vessel N/O ANTEA. During these cruises and surveys, 80 OBS, Ocean Bottom Seismometers, 64 of which with 3-components seismometers and hydrophones, and 20 OBH with hydrophones have been brought together from several pools (Geoazur Nice, INSU/IPGP Paris, IfM-GEOMAR Kiel, AWI Bremerhaven), with up to 30 land stations (CSIC Barcelona, IPG Paris, INSU-RLBM and -Lithoscope, ETH Zurich). The deployment of all these instruments has been supported principally in addition by ANR Catastrophes Telluriques et Tsunamis (SUBSISMANTI), by the EU SALVADOR Programme of IFM-GEOMAR, as well as by the EU project THALES WAS RIGHT. The main goal of this large seismic investigation effort is the understanding of the behaviour of the seismogenic zone and location of potential source regions of mega-thrust earthquakes. Specific goals are the mapping of the subduction interplate in the range where it may be seismogenic along the Lesser Antilles Arc from Antigua to Martinique Islands, as a contribution to identification and localisation in advance of main rupture zones of possible future major earthquakes, and to the search for transient signals of the activity. The forearc region, commonly considered as a proxy to the seismogenic portion of the subduction mega-thrust fault plane, and which is here the main target has been localized along 3 transects to the Arc, thanks to a preliminary survey in 2001, the French SISMANTILLES cruise. We will present the first results obtained during these experiments dedicated specifically to image at depth the seismic structure and activity of this region. To image faults at depth and the detailed upper-crustal structure, 3700 km of multi-beam bathymetry and multi-channel reflection seismic profiles have been collected along a grid comprising 7 strike-lines of up to 300 km long and spaced by 15 km and 12 transects of up to 150 km long and spaced by 25 km (SISMANTILLES II). All these airgun shots dedicated to deep penetration have been recorded by the 80 OBSs and 20 OBHs deployed by the F/S Merian and N/O Atalante on the nodes of this grid of profiles. It will permit to get Vp constraints on the deep forearc region and mantle wedge by wide-angle refraction studies, as well as constraints on the updip and downdip limits of the seismogenic part of the mega-thrust fault plane. Two of these transects have been extended across the whole arc during the TRAIL survey, with up to 50 OBSs deployed along both 240 km long profiles. All these OBSs remained several months after the shot experiments to gather data for accurate location of local earthquakes and possibly Vp and Vp/Vs tomography. They have been recovered and partly redeployed by N/O Antea during the OBSANTILLES survey. A significant number of those instruments had broadband seismometers, a notable originality in the case of the OBSs to probe the conditions for detecting low-frequency transient signals which have been found recently in the case of the Cascadia and Central Japan subductions and associated to their seismogenic character.

Enhanced global seismic resolution using proposed undersea cables

NASA Astrophysics Data System (ADS)

Ranasinghe, N. R.; Rowe, C. A.; Larmat, C. S.; Syracuse, E. M.; Begnaud, M. L.

2016-12-01

With the exception of a few isolated, near-shore deployments of Ocean-bottom seismometers (OBS's), most seismic instrumentation on the Earth is located on land, although two thirds of the Earth's surface is covered with oceans. Most large earthquakes are unevenly distributed along the Earth's subduction zones; hence, large areas of the Earth are unevenly sampled in terms of seismic rays. The goal of this work is to produce a comparison of seismic ray coverage of the Earth with today's seismic stations to that which might be possible in the future if densely-instrumented transoceanic cables are deployed.Our work is motivated by the planning of a Joint Task Force under the UN that is proposing to integrate seismic sensors at intervals as small as 75 km along the next generation of oceanic telecommunication cables. These sensors offer the potential to improve global geophysical models as well as reduce event detection thresholds and location uncertainties in poorly characterized regions. Data coverage is first estimated via an infinite-frequency ray-tracing utility (Pcalc) that is used to predict seismic propagation in support of the United States effort towards nuclear explosion monitoring. We have predicted P-wave raypaths from 1668 earthquakes to 4421 seismic stations to produce global raypath density images in the crust and mantle. We present the improvement in ray coverage achieved at crustal and mantle depths by the addition of 1382 sensors along the telecommunication cables and we discuss the areas in which our models and earthquake characterization benefits from these proposed instruments. Because the Earth's complex 3D structure can have frequency-dependent effects on seismic propagation, we also employ a spectral element method (SPECFEM3D) to compute finite-frequency kernels that include the first order of scattering produced by 3D anomalies, and we present progress on this effort to compare with our infinite-frequency predictions.

Seismometer reading from impact made by Lunar Module ascent stage

NASA Image and Video Library

1969-11-20

S69-59547 (20 Nov. 1969) --- The seismometer reading from the impact made by the Lunar Module ascent stage when it struck the lunar surface. The impact was registered by the Passive Seismic Experiment Package which was deployed on the moon by the Apollo 12 astronauts. PSEP, which is a component of the Apollo Lunar Surface Experiments Package, will detect surface tilt produced by tidal deformations, moonquakes, and meteorite impacts. The LM's ascent stage was jettisoned and sent journeying toward impact on the moon after astronauts Charles Conrad Jr. and Alan L. Bean returned to lunar orbit and rejoined astronaut Richard F. Gordon Jr. in the Command and Service Modules. Information from the PSEP is transmitted to Earth through the ALSEP's central station and monitored by equipment at the Manned Spacecraft Center.

Seismic Coupling of Short-Period Wind Noise Through Mars' Regolith for NASA's InSight Lander

NASA Astrophysics Data System (ADS)

Teanby, N. A.; Stevanović, J.; Wookey, J.; Murdoch, N.; Hurley, J.; Myhill, R.; Bowles, N. E.; Calcutt, S. B.; Pike, W. T.

2017-10-01

NASA's InSight lander will deploy a tripod-mounted seismometer package onto the surface of Mars in late 2018. Mars is expected to have lower seismic activity than the Earth, so minimisation of environmental seismic noise will be critical for maximising observations of seismicity and scientific return from the mission. Therefore, the seismometers will be protected by a Wind and Thermal Shield (WTS), also mounted on a tripod. Nevertheless, wind impinging on the WTS will cause vibration noise, which will be transmitted to the seismometers through the regolith (soil). Here we use a 1:1-scale model of the seismometer and WTS, combined with field testing at two analogue sites in Iceland, to determine the transfer coefficient between the two tripods and quantify the proportion of WTS vibration noise transmitted through the regolith to the seismometers. The analogue sites had median grain sizes in the range 0.3-1.0 mm, surface densities of 1.3-1.8 g cm^{-3}, and an effective regolith Young's modulus of 2.5^{+1.9}_{-1.4} MPa. At a seismic frequency of 5 Hz the measured transfer coefficients had values of 0.02-0.04 for the vertical component and 0.01-0.02 for the horizontal component. These values are 3-6 times lower than predicted by elastic theory and imply that at short periods the regolith displays significant anelastic behaviour. This will result in reduced short-period wind noise and increased signal-to-noise. We predict the noise induced by turbulent aerodynamic lift on the WTS at 5 Hz to be ˜2×10^{-10} ms^{-2} Hz^{-1/2} with a factor of 10 uncertainty. This is at least an order of magnitude lower than the InSight short-period seismometer noise floor of 10^{-8} ms^{-2} Hz^{-1/2}.

The Anisotropic Structure of South China Sea: Using OBS Data to Constrain Mantle Flow

NASA Astrophysics Data System (ADS)

Li, L.; Xue, M.; Yang, T.; Liu, C.; Hua, Q.; Xia, S.; Huang, H.; Le, B. M.; Huo, D.; Pan, M.

2015-12-01

The dynamic mechanism of the formation of South China Sea (SCS) has been debated for decades. The anisotropic structure can provide useful insight into the complex evolution of SCS by indicating its mantle flow direction and strength. In this study, we employ shear wave splitting methods on two half-year seismic data collected from 10 and 6 passive source Ocean Bottom Seismometers (OBS) respectively. These OBSs were deployed along both sides of the extinct ridge in the central basin of SCS by Tongji University in 2012 and 2013 respectively, which were then successfully recovered in 2013 and 2015 respectively. Through processing and inspecting the global and regional earthquakes (with local events being processing) of the 2012 dataset, measurements are made for 2 global events and 24 regional events at 5 OBSs using the tangential energy minimization, the smallest eigenvalue minimization, as well as the correlation methods. We also implement cluster analysis on the splitting results obtained for different time windows as well as filtered at different frequency bands. For teleseismic core phases like SKS and PKS, we find the fast polarization direction beneath the central basin is approximately NE-SW, nearly parallel to the extinct ridge in the central basin of SCS. Whereas for regional events, the splitting analysis on S, PS and ScS phases shows much more complicated fast directions as the ray path varies for different phases. The fast directions observed can be divided into three groups: (1) for the events from the Eurasia plate, a gradual rotation of the fast polarization direction from NNE-SSW to NEE-SWW along the path from the inner Eurasia plate to the central SCS is observed, implying the mantle flow is controlled by the India-Eurasia collision; (2) for the events located at the junction of Pacific plate and Philippine plate, the dominant fast direction is NW-SE, almost perpendicular to Ryukyu Trench as well as sub-parallel to the absolute direction of Philippine plate; (3) for the events occurred in the SE direction near the Philippine Fault zone, the observed NE-SW fast direction is sub-parallel to the subduction direction of the Philippine plate.

Spatial distribution of non volcanic tremors offshore eastern Taiwan

NASA Astrophysics Data System (ADS)

Xie, X. S.; Lin, J. Y.; Hsu, S. K.; Lee, C. H.; Liang, C. W.

2012-04-01

Non-volcanic tremor (NVT), originally identified in the subduction zone of the southwest Japan, have been well studied in the circum-Pacific subduction zones and the transform plate boundary in California. Most studies related NVT to the release of fluids, while some others associated them with slow-slip events, and can be triggered instantaneously by the surface waves of teleseismic events. Taiwan is located at a complex intersection of the Philippines Sea Plate and the Eurasian Plate. East of Taiwan, the Philippine Sea plate subducts northward beneath the Ryukyu arc. The major part of the island results from the strong convergence between the two plates and the convergent boundary is along the Longitudinal Valley. Moreover, an active strike-slip fault along the Taitung Canyon was reported in the offshore eastern Taiwan. In such complicate tectonic environments, NVT behavior could probably bring us more information about the interaction of all the geological components in the area. In this study, we analyze the seismic signals recorded by the Ocean bottom Seismometer (OBS) deployed offshore eastern Taiwan in September 2009. TAMS (Tremor Active Monitor System) software was used to detect the presence of NVT. 200 tremor-like signals were obtained from the 3 weeks recording period. We use the SSA (Source-Scanning Algorithm) to map the possible distribution of the tremor. In total, 180 tremors were located around the eastern offshore Taiwan. The tremors are mainly distributed in two source areas: one is along the Taitung Canyon, and the other is sub-parallel to the Ryukyu Trench, probably along the plate interface. Many tremors are located at depth shallower than 5 km, which suggests a possible existence of a weak basal detachment along the sea bottom. Other tremors with larger depth may be related to the dehydration of the subducting sea plate as suggested by the former studies. Limited by the short recording period of the OBS experiment, we could not obtain any possible repeating interval and the spatial migration about the tremor occurrence. However, the presence of NVT offshore eastern Taiwan shown in our study still brings us valuable understanding about the undergoing tectonic processes in the marine area.

Seismic velocity structures of the transitional crust across the northeastern margin of the South China Sea

NASA Astrophysics Data System (ADS)

Xiaoli, W.; Li, C. F.

2017-12-01

A wide-angle OBS profile (OBS2016-2) was simulated by using forward method, in order to investigate the structures of the transition crust across the northeastern margin of the South China Sea (SCS). Reflection and refraction data recorded at 14 ocean bottom seismometers (OBS) along the NW-SE profile of 320 km long are integrated to image the Cenozoic (1.7-3.3 km/s) sediment and Mesozoic (4.2-5.3 km/s) sediment at northeastern Chaoshan Depression, the upper (5.5 km/s-6.3 km/s) and lower (6.4 km/s-6.9 km/s) crust successfully. The 2-D velocity-depth models are obtained by using the 2-D forward ray-tracing RayInvr software (Zelt and Smith, 1992). The initial model is established based on single channel seismic profile, the seismic phases of the 14 OBSs and the regional geologic and geophysical data. The velocity model reveals that the thickness of sediment (1.2-5.5 km) varies strongly from onshore to offshore due to the seafloor spreading of the SCS. Several relict volcanoes are identified in the upper crust (2.1-8.1 km) by single channel seismic data acquisited along the same profile. The depth of MOHO interface in the velocity model decreases seaward gradually from 26.8 to 10.8 km. Ocean-continent transition zone in the northeastern margin of the SCS is characterized by several volcanoes and igneous rocks in the upper crust.

The Hawaiian PLUME Project Successfully Completes its First Deployment

NASA Astrophysics Data System (ADS)

Laske, G.; Collins, J. A.; Wolfe, C. J.; Weeraratne, D.; Solomon, S. C.; Detrick, R. S.; Orcutt, J. A.; Bercovici, D. A.; Hauri, E. H.

2006-12-01

The Hawaiian PLUME (Plume-Lithosphere Undersea Melt Experiment) project is a multi-disciplinary program to study the deep mantle roots of the Hawaiian hotspot. The nearly linear alignment of the Hawaiian Islands has heretofore prevented high-resolution, three-dimensional imaging of mantle structure in the region from land seismic observations, a situation that has permitted debates to persist over whether or not the Hawaiian hotspot is underlain by a classical plume from the deep mantle and how mantle upwelling interacts with the overlying lithosphere beneath the Hawaiian Swell. The centerpiece of the PLUME project is a large broadband seismic network that includes ocean-bottom seismometers (OBSs) as well as portable land stations. Occupying a total of more than 80 sites and having a two-dimensional aperture of more than 1000~km, this network includes one of the first large-scale, long-term deployments of broadband OBSs. The seismic experiment has been conducted in two stages to record teleseismic body and surface waves over a total duration of two years. A first deployment of 35 OBSs extended from January 2005 through January 2006 and was centered on the island of Hawaii, the locus of the hotspot. A second OBS deployment, with a larger aperture and larger station spacing was carried out in May 2006 to collect data for another year. The first deployment was a technical success, with 32 of 35 OBSs recovered and many large events at suitable distances and azimuths well recorded. We recorded 225 events with scalar seismic moments greater than 5× 1017Nm. Our database includes the great 28 March 2005, M_S=8.2 aftershock of the 26 December 2004 Sumatra-Andaman earthquake and two large earthquakes on the Juan de Fuca plate on 15 and 17 June 2005. Our surface wave analysis will be based on 102 large, shallow (h_0<200 km) earthquakes with scalar seismic moments M_0≥ 20/times 1017Nm. This number of events is about 20% more than what was gathered during the year--long SWELL pilot deployment in the same region in 1997-98 using solely differential pressure gauges. The database also includes excellent long-period body wave waveforms suitable for tomographic imaging as well as horizontal- component data suitable for a shear-wave splitting analysis and for identifying converted phases from the upper-mantle transition zone with receiver function techniques. In addition to the seismic experiment, nine of eleven dredges on the first deployment cruise yielded coral and basalt samples that will help to constrain subsidence rates of the Hawaiian Islands and the origin of rift volcanism. On the two deployment cruises we also obtained high-resolution multi-beam bathymetry along previously unmapped transects covering areas of the eastern parts of the Maui and the Molokai Fracture Zones as well as portions of the Bach Ridge at the southern end of the Musician Seamounts.

Improving the resolution of the 2010 Haiti earthquake fault geometry using temporary seismometer deployments

NASA Astrophysics Data System (ADS)

Douilly, R.; Haase, J. S.; Ellsworth, W. L.; Bouin, M.; Calais, E.; Armbruster, J. G.; Mercier De Lepinay, B. F.; Deschamps, A.; Saint Louis, M.; Meremonte, M. E.; Hough, S. E.

2011-12-01

Haiti has several active faults that are capable of producing large earthquakes such as the 2010 Mw 7.0 Haiti earthquake. This earthquake was not unexpected, given geodetic measurements showing strain accumulation on the Enriquillo Plantain Garden Fault Zone, the major fault system in southern Haiti (Manaker et al. 2008). GPS and INSAR data (Calais et al., 2010) show, however, that this rupture occurred on the previously unmapped Léogâne fault, a 60° north dipping oblique blind thrust located immediately north of the Enriquillo Fault. Following the earthquake, several groups installed temporary seismic stations to record aftershocks. Natural Resources Canada installed three broadband seismic stations, Géoazur installed 21 ocean bottom seismometers, L'Institut de Physique du Globe de Paris installed 5 broadband seismometers, and the United States Geological Survey deployed 17 short period and strong motion seismometers in and around Port-au-Prince. We use data from this complete set of stations, along with data from permanent regional stations, to relocate all of the events from March 17 to June 24, to determine the regional one-dimensional crustal structure and determine focal mechanisms. The aftershock locations from the combined data set clearly delineate the Léogâne fault. The strike and dip closely agrees with that of the global centroid moment tensor solution, but appears to be more steeply dipping than the finite fault inversions. The aftershocks also delineate a flat structure on the west side of the rupture zone and may indicate triggered seismicity on the Trois Baies fault, although the depths of these events are not as well constrained. There is no clear evidence for aftershocks on the other rupture segments inferred in the Hayes et al. (2010) mainshock rupture model. There is a cluster of aftershocks in the hanging wall near the western patch of high slip identified by Calais et al. (2010) and Meng et al. (2011), or central patch in the Hayes et al. (2010) model. We use first-motion focal mechanism solutions to clarify the relationship of the fault geometry to the mechanisms of the larger events.

Tracking fin whales in the northeast Pacific Ocean with a seafloor seismic network.

PubMed

Wilcock, William S D

2012-10-01

Ocean bottom seismometer (OBS) networks represent a tool of opportunity to study fin and blue whales. A small OBS network on the Juan de Fuca Ridge in the northeast Pacific Ocean in ~2.3 km of water recorded an extensive data set of 20-Hz fin whale calls. An automated method has been developed to identify arrival times based on instantaneous frequency and amplitude and to locate calls using a grid search even in the presence of a few bad arrival times. When only one whale is calling near the network, tracks can generally be obtained up to distances of ~15 km from the network. When the calls from multiple whales overlap, user supervision is required to identify tracks. The absolute and relative amplitudes of arrivals and their three-component particle motions provide additional constraints on call location but are not useful for extending the distance to which calls can be located. The double-difference method inverts for changes in relative call locations using differences in residuals for pairs of nearby calls recorded on a common station. The method significantly reduces the unsystematic component of the location error, especially when inconsistencies in arrival time observations are minimized by cross-correlation.

Tidal Triggering and Statistical Patterns of Microseismicity at Axial Volcano on the Juan de Fuca Ridge

NASA Astrophysics Data System (ADS)

Bohnenstiehl, D. R.; Dziak, R. P.; Caplan-Auerbach, J.; Haxel, J. H.; Mann, M. E.; Pennington, C.; Weis, J.; Womack, N.; Levy, S.

2015-12-01

Tidal stress changes are known to modulate the timing of microearthquakes within many mid-ocean ridge volcanic systems. At Axial Volcano, located on the Juan de Fuca Ridge, earthquakes occur preferentially when volumetric extension peaks near times of low ocean tide. Autonomous ocean-bottom hydrophone (OBH, 2007-2011) and cabled ocean bottom seismometer (OBS, Nov. 2014-) data are used to quantify the strength of tidal triggering in time periods before the April 2011 and April 2015 eruptions at Axial Volcano. The mean percent excess at times of low ocean-tide is ~14% (16% std) in the four years prior to the 2011 eruption and ~18% (17% std) in the five months prior to the 2015 eruption. The sensitivity of earthquakes to tidal stress does not evolve systematically prior to either eruption; however, this pattern is disturbed by much larger stress changes associated with the onset of dike intrusion. Following dike injection and eruption, seismicity rates drop sharply. As seismicity rates continue to rise in the months following the 2015 eruption, real-time data available from the cabled OBS network will be used quantify temporal patterns in microearthquake activity as dike induced stresses are relaxed and the magma chamber inflates.

A broad-band microseismometer for planetary operations

NASA Technical Reports Server (NTRS)

Banerdt, W. B.; Vanzandt, T.; Kaiser, W. J.; Kenny, T. W.

1993-01-01

There has recently been renewed interest in the development of instrumentation for making measurements on the surface of Mars. This is due to the Mars Environmental Survey (MESUR) Mission, for which approximately 16 small, long-lived (2-10 years), relatively inexpensive surface stations will be deployed in a planet-wide network. This will allow the investigation of processes (such as seismology and meteorology) which require the simultaneous measurement of phenomena at many widely spaced locations on the surface over a considerable length of time. Due to the large number of vehicles involved, the mass, power, and cost of the payload will be severely constrained. A seismometer has been identified as one of the highest priority instruments in the MESUR straw-man payload. The requirements for an effective seismic experiment on Mars place a number of constraints on any viable sensor design. First, a large number of sensors must be deployed in a long-lived global network in order to be able to locate many events reliably, provide good spatial sampling of the interior, and increase the probability of seismic detection in the event of localized seismicity and/or high attenuation. From a practical standpoint, this means that individual surface stations will necessarily be constrained in terms of cost, mass, and power. Landing and thermal control systems will probably be simple, in order to minimize cost, resulting in large impact accelerations and wide daily and seasonal thermal swings. The level of seismic noise will determine the maximum usable sensitivity for seismometer. Unfortunately, the ambient seismic noise level for Mars is not well known. However lunar seismic noise levels are several orders of magnitude below that of the Earth. Sensitivities on the order of 10(exp -11)g over a bandwidth of .04 to 20 Hz are thought to be necessary to fulfill the science objectives for a seimometer placed on the Martian surface. Silicon micromachined sensor technology offers techniques for the fabrication of monolithic, robust, compact, lower power and mass accelerometers. Conventional micro-machined accelerometers have been developed and are commercially available for high frequency and large acceleration measurements. The new seismometer we are developing incorporates certain principles of conventional silicon micromachined accelerometer technology. However, currently available silicon micromachined sensors offer inadequate sensitivity and bandwidth for the Mars seismometer application. Our implementation of an advanced silicon micromachined seismometer is based on principles recently developed at JPL for high-sensitivity position sensor technology.

Transition of the Taiwan-Ryukyu collision-subduction process as revealed by ocean-bottom seismometer observations

NASA Astrophysics Data System (ADS)

Chin, Shao-Jinn; Lin, Jing-Yi; Chen, Yen-Fu; Wu, Wen-Nan; Liang, Chin-Wei

2016-10-01

Located at the arc-continental collision region between the Eurasian (EP) and Philippine Sea Plates (PSP), Taiwan is usually considered to have a complex tectonic environment, particularly along the eastern coast of the island. To gain a better understanding of the geological evolution of the east Taiwan area, the data from 8 Ocean Bottom Seismometers (OBS) acquired during the Across Taiwan Strait Explosion Experiment in 2012 and 14 inland seismic stations were used to determine a more detailed and accurate distribution of marine earthquakes. Based on the 333 relocated earthquakes and available geophysical data, we suggest two main tectonic boundaries for eastern Taiwan. South of 23.25°N, the homogeneous distribution of earthquakes in the crustal portion for both the inland and offshore areas suggests an ongoing collisional process. North of this location, between approximately 23.25°N and 23.8°N, the abrupt increasing of seismicity depth infers that the underthrusted arc/fore-arc material is deforming due to the collisional compression at depth. In this segment, the subsidence of the arc/fore-arc area determines the transition from collision to subduction. North of 23.8°N, the northwestern dipping PSP is well illustrated by the seismicity both onshore and offshore, indicating a dominant subduction process.

Recent Seismic Experiments of OBS in the South China Sea

NASA Astrophysics Data System (ADS)

Ruan, A.; Li, J.; Wu, Z.

2012-12-01

Since 2006 some research institutions of China have carried out some important seismic experiments by using ocean bottom seismometer(OBS) in the South China Sea (SCS) and obtained many concrete progresses in modeling the crustal structure of SCS and also in understanding of its formation and evolution as well. In 2006 three wide-angle profiles were completed in the northern margin, named OBS2006-1 across the northwestern sub-basin, OBS2006-2 parallel to the sea basin boundary and OBS2006-3 across the Dongsha Rise and Chaoshan Depression respectively. In 2010 two wide- angle profiles were completed, named OBS2010-1 and OBS 2010-2 both perpendicular to the northern off-shore faulting system. During 2009-2011 four wide-angle profiles were completed in the southern margin, named OBS973-1 from southern margin to the southwestern sub-basin, OBS973-2 from Liyue Bank to the southwestern sub-basin and OBS973-3 from Xisha to the southwestern sub-basin, OBS2011-2 from Xisha to Hainan Island respectively. In 2011 two 3D seismic array of OBS were completed in the Zhongnan-Changlong sea mount chain and Huangyan-Zhenbei sea mount chain respectively. Here we present some primary but important results as follows. (1) The velocity model of OBS2006-1 indicates that the crust under the continental slope decreases from 21km to 11km, and to 7.7km in the northwestern sub-basin with Moho depth ascends from 21km to 11km. The tectonic geometry and velocity structure of the northwestern sub-basin and its margins on both sides shows symmetrical and conjugate and indicates pure shear mode of continental margin rifting mechanism. (2) The velocity model of OBS2006-3 reveals remarkable thickness with maximum 8 km of the Mesozoic sediment in Chaoshan Depression in which velocity increases downward from 4.4 km/s at top to 5.3 km/s at the bottom. The buried depth of Moho decreases from 24-25 km under Dongsha Rise to 17 km in the lower slope and an obviously velocity abnormal is detected in the upper crust of the Dongsha Rise and its velocity raises to 6.9 km/s due to the mantle underplating and magma activities. A high velocity layer (HVL) of 3-12 km thick is found in the lower crust, and its velocity is 7.1-7.4 km/s. (3) The wide angle seismic profile-OBS973-2 that extends in NW-SE direction 369km long from the northeastern Liyue Bank to the central sub-basin. It indicates that there are some small volcanoes on the top of crust in Liyue Bank and P wave velocities downward increase from 5.5~6.4km/s in the upper crust (9~10km thick) to 6.6~7.1km/s in the lower crust (11km thick). In the transition zone and sea basin P wave velocities downward increase from 5.9~6.1km/s in the upper curst (4~5km thick) to 6.6~6.9km/s in the lower crust (2~4km thick). The buried depth of Moho is 23km in Liyue Bank and 8~12km in the sea basin. The comparison of profile OBS973-2 with profile OBS2006-1 in the northern margin shows remarkable similarity between them and suggests a possibility of conjugation relationship between Liyue Bank and Zhongsha Massif. Acknowledgements This work was supported by the National Natural Science Foundation of China (91028006,40876035,41106053 and 41176046) and the National Basic Research Program of China (2007CB411701) .

Improving the study of the seismicity in the western and central parts of the Sea of Marmara using Ocean Bottom Seismometers

NASA Astrophysics Data System (ADS)

Cros, Estelle; Géli, Louis; Bayrakci, Gaye; Cagatay, Namik; Gürbüz, Cemil

2013-04-01

The Marmara Sea is located between the Agean Sea and the Black Sea, along the North Anatolian strike-slip fault, which experienced a sixty year sequence of earthquakes since 1940. Prior to this sequence, which ended with the Izmit and Duzce earthquakes in 1999, at the eastern end of the Sea of Marmara (SoM), the fault ruptured to the west in 1912 in Ganos, with an estimated moment magnitude of 7.4. Therefore, a major earthquake is expected within the SoM seismic gap. In order to better understand the seismicity and to reduce the threshold of detection, a network of ten OBS with four components was deployed by Ifremer with R/V Yunus of Istanbul Technical University, in the western and central parts of the Marmara Sea to record the micro-seismicity from the immediate vicinity of the main Marmara Fault, between April and August, 2011. The network was specifically designed to survey the segments crossing the Western High, where gas hydrates where recently found, the Central Basin and the Kumburgaz Basin. During this period more than one hundred earthquakes were detected by the EMSC (European-Mediterranean Seismological Centre) in the Sea of Marmara. Because the basins of the Sea of Marmara are filled with more than 5 km of Plio- Quaternary soft ("slow") sediments, it is of critical importance to take into account the velocity structure of the offshore domain, which is drastically different from the one onshore, and the bathymetry. To improve the localization of seismic events, a 3D velocity model was thus considered and implemented in the Sytmis software developed by INERIS. This model is based on the tomographic data collected in 2001 using a controlled source experiment and on the numerous multichannel seismic profiles that provide information on, respectively, the deeper structures and the upper, sedimentary layers. Preliminary results are presented. Special focus will be given on the clustering of the micro-seismicity in the Western High and on a swarm event. As a perspective to future work, an attempt will be made to improve earthquake locations using the dataset from the permanent, cabled, Ocean Bottom Broad-Band Seismometers network operated by KOERI.

OBS Data Denoising Based on Compressed Sensing Using Fast Discrete Curvelet Transform

NASA Astrophysics Data System (ADS)

Nan, F.; Xu, Y.

2017-12-01

OBS (Ocean Bottom Seismometer) data denoising is an important step of OBS data processing and inversion. It is necessary to get clearer seismic phases for further velocity structure analysis. Traditional methods for OBS data denoising include band-pass filter, Wiener filter and deconvolution etc. (Liu, 2015). Most of these filtering methods are based on Fourier Transform (FT). Recently, the multi-scale transform methods such as wavelet transform (WT) and Curvelet transform (CvT) are widely used for data denoising in various applications. The FT, WT and CvT could represent signal sparsely and separate noise in transform domain. They could be used in different cases. Compared with Curvelet transform, the FT has Gibbs phenomenon and it cannot handle points discontinuities well. WT is well localized and multi scale, but it has poor orientation selectivity and could not handle curves discontinuities well. CvT is a multiscale directional transform that could represent curves with only a small number of coefficients. It provide an optimal sparse representation of objects with singularities along smooth curves, which is suitable for seismic data processing. As we know, different seismic phases in OBS data are showed as discontinuous curves in time domain. Hence, we promote to analysis the OBS data via CvT and separate the noise in CvT domain. In this paper, our sparsity-promoting inversion approach is restrained by L1 condition and we solve this L1 problem by using modified iteration thresholding. Results show that the proposed method could suppress the noise well and give sparse results in Curvelet domain. Figure 1 compares the Curvelet denoising method with Wavelet method on the same iterations and threshold through synthetic example. a)Original data. b) Add-noise data. c) Denoised data using CvT. d) Denoised data using WT. The CvT can well eliminate the noise and has better result than WT. Further we applied the CvT denoise method for the OBS data processing. Figure 2a is a common receiver gather collected in the Bohai Sea, China. The whole profile is 120km long with 987 shots. The horizontal axis is shot number. The vertical axis is travel time reduced by 6km/s. We use our method to process the data and get a denoised profile figure 2b. After denoising, most of the high frequency noise was suppressed and the seismic phases were clearer.

Analysis and localization of blue whale vocalizations in the Solomon Sea using waveform amplitude data.

PubMed

Frank, Scott D; Ferris, Aaron N

2011-08-01

During the Woodlark Basin seismic experiment in eastern Papua New Guinea (1999-2000), an ocean-bottom seismic array recorded marine mammal vocalizations along with target earthquake signals. The array consisted of 14 instruments, 7 of which were three-component seismometers with a fourth component hydrophone. They were deployed at 2.0-3.2 km water depth and operated from September 1999 through February 2000. While whale vocalizations were recorded throughout the deployment, this study focuses on 3 h from December 21, 1999 during which the signals are particularly clear. The recordings show a blue whale song composed of a three-unit phrase. That song does not match vocalization characteristics of other known Pacific subpopulations and may represent a previously undocumented blue whale song. Animal tracking and source level estimates are obtained with a Bayesian inversion method that generates probabilistic source locations. The Bayesian method is augmented to include travel time estimates from seismometers and hydrophones and acoustic signal amplitude. Tracking results show the whale traveled northeasterly over the course of 3 h, covering approximately 27 km. The path followed the edge of the Woodlark Basin along a shelf that separates the shallow waters of the Trobriand platform from the deep waters of the basin.

Results of the first Seismometer to Investigate Ice and Ocean Structure (SIIOS) Analogue Mission

NASA Astrophysics Data System (ADS)

Della-Giustina, Daniella; Bray, Veronica; "Hop" Bailey, Samuel; Pettit, Erin; Schmerr, Nicholas; Dahl, Peter; Avenson, Brad; Byrne, Shane; SIIOS Team

2017-10-01

The icy moons of Europa and Enceladus are thought to have global subsurface oceans in contact with mineral-rich interiors, likely providing the ingredients needed for life as we know it. The possibility of life forming in the ocean or in melt pockets, relies on the presence of a source of energy and chemistry for biological molecule formation. A thick, stagnant ice crust would likely prevent transfer of oxidants from the surface to the water, halting the development of life. The ice thickness and structure is therefore one of the most important and controversial topics in astrobiology.The best way to access an icy moon’s interior structure is with a lander-based seismometer. Our team has identified a commercial-off-the-shelf device as a flight-candidate for operation in the extreme environment of the icy moons. Based on estimates of Europan seismicity, the flight candidate device is sensitive enough to detect the ice-water boundary and pockets of liquid within the ice. Its low mass and low power enables deployment of multiple seismometers in a short-baseline array on a lander. The performance, mass, and volume of this device meet or exceed flight requirements identified in lander studies making a field test of these seismometers highly representative of a flight unit developed for an Ocean Worlds mission.We report the results of the first field campaign for the SIIOS Analogue Mission Program (AMP), which has evaluates the performance of the flight candidate seismometer in Ocean World terrestrial analogue environments. In particular, the first SIIOS AMP field exercise is performed at Gulkana Glacier, Alaska. During the summer melt season Gulkana provides kilometer-scale regions of coexisting ice, water, and silicate material, thereby providing areas with the desired analogue seismic contrasts. During this first mission, we have demonstrated device sensitivity to the detection of seismicity from high frequency (> 50 Hz) active and passive sources, the depth of ice-water boundaries, and to the ice properties using a short-baseline (1 m2) seismic array and a “lander-mounted” single station seismometer.

Upper Mantle Seismic Anisotropy Beneath West Antarctica from Shear Wave Splitting Analysis of POLENET/ANET Data

NASA Astrophysics Data System (ADS)

Accardo, N.; Wiens, D. A.; Hernandez, S.; Aster, R. C.; Nyblade, A.; Anandakrishnan, S.; Huerta, A. D.; Wilson, T. J.

2011-12-01

We constrain azimuthal anisotropy in the Antarctic upper mantle using shear wave splitting parameters obtained from teleseismic SKS, SKKS, and PKS phases recorded at 30 broad-band seismometers deployed in West Antarctica, and the Transantarctic Mountains as a part of POLENET/ANET. The first seismometers were deployed in late 2007 and additional seismometers were deployed in 2008 and 2009. The seismometers generally operate year-round using solar power, insulated boxes, and either rechargeable AGM or primary lithium batteries. We used an eigenvalue technique to linearize the rotated and shifted shear wave particle motions and determine the best splitting parameters. Robust windows around the individual phases were chosen using the Teanby cluster-analysis algorithm. We visually inspected all results and assigned a quality rating based on factors including signal-to-noise ratios, particle motions, and error contours. The best results for each station were then stacked to get an average splitting direction and delay time. The delay times range from 0.33 to 1.33 s, but generally average about 1 s. We conclude that the splitting results from anisotropy in the upper mantle, since the large splitting times cannot be accumulated in the relatively thin crust (20-30 km) of the region. Overall, fast directions in West Antarctica are at large angles to the direction of Antarctic absolute plate motion in either hotspot or no-net rotation frameworks, showing that the anisotropic fabric does not result from shear associated with the motion of Antarctica over the mantle. The West Antarctic fast directions are also much different than those found in East Antarctica by previous studies. We suggest that the East Antarctic splitting results from anisotropy frozen into the cold cratonic continental lithosphere, whereas West Antarctic splitting is related to Cenozoic tectonism. Stations within the West Antarctic Rift System (WARS), a region of Cenozoic extension, show fast directions subparallel to the inferred WARS extension direction. Stations located in the Ellsworth-Whitmore Mountains (EWM) show fast directions parallel to those found within WARS. Furthermore, results from WARS and from EWM all show relatively large splitting times of 0.6 - 1.33 s. These results suggest upper mantle anisotropy that results from mantle flow and deformation related to the extensional deformation of the region. Two stations were installed in the Pensacola Mountains which are located grid-north of the EWM. The results from this region deviate from the dominant fast orientation seen in WARS but appear to be approximately perpendicular to the strike of the mountain range. Stations in Marie Byrd Land (MBL) show inconsistent fast directions and a wide range of delay times (0.3 - 0.9 s), perhaps as a result of complex mantle fabric related to a possible MBL hotspot.

Seismicity and state of stress near the Japan Trench axis off Miyagi, northeast Japan, after the 2011 Tohoku-Oki earthquake

NASA Astrophysics Data System (ADS)

Obana, K.; Kodaira, S.; Takahashi, T.; Yamamoto, Y.; Nakamura, Y.; No, T.; Fujie, G.; Hino, R.; Shinohara, M.

2013-12-01

The 2011 Tohoku-Oki earthquake ruptured roughly 200 km wide and 500 km long megathrust along the Japan Trench. The rupture propagated to the trench axis with a maximum slip about 50 m near the trench axis. As a consequence of this large near-trench slip, earthquakes have been activated near the axis of the Japan Trench off Miyagi, northeast Japan. We have conducted ocean bottom seismograph (OBS) experiments in the Japan Trench axis area, surrounding area of the IODP JFAST drilling site, since the occurrence of the 2011 Tohoku-Oki earthquake. Although conventionally used OBS cannot be deployed at seafloor deeper than 6000 m water depth, we used newly developed ultra-deep OBS using ceramic sphere, which can be deployed at a depth of 9000 m, for the observations in the trench axis. The ultra-deep OBS has almost equivalent dimensions and weight with the conventionally used OBS, thus we can handle it in the same manner with the conventionally OBS without any special operation. As a result of a series of the OBS observations, we obtained accurate hypocenter locations and focal mechanisms in both seaward and landward of the trench axis. Earthquakes near the trench axis area were located within the overriding and incoming/subducting plates with very few on the plate interface below the inner trench slope landward of the trench axis. Most of the earthquakes both in the overriding and incoming/subducting plates having normal or strike-slip faulting focal mechanisms with T-axis normal to the trench axis. This indicates that tensional stress is dominant in the trench axis area. However, most seaward part of the seismicity within the overriding plate is characterized by a localized cluster of trench-normal compressional earthquakes, which may relate to spatial variation of the frictional behavior of the shallowest part of the megathrust. On the other hand, trench-normal extensional earthquakes in the incoming/subducting Pacific plate were located at depths shallower than about 35 to 40 km. The deepest trench-normal extensional earthquake observed during OBS observations from December 2012 to January 2013 is slightly shallower than that observed from May to June in 2011 but further observations are required to investigate the temporal change. Continued and repeated earthquake observations could provide information on post-seismic behavior of the megathrust and recovery process of the stress state.

Some possible causes of and corrections for STS-1 response changes in the Global Seismographic Network

USGS Publications Warehouse

Hutt, C.R.; Ringler, A.T.

2011-01-01

The Global Seismographic Network (GSN) (Figure 1) plays a key role in providing seismic data for global earthquake monitoring (e.g., Benz et al. 2005), earthquake science (e.g., Tsai et al. 2005), and studies of Earth structure (e.g., Dalton et al. 2008). One of the key GSN design goals is to "provide high fidelity digital recordings of all teleseismic ground motions (adequate to resolve at or near ambient noise up to the largest teleseismic signals over the bandwidth from free oscillations (10-4 Hz) to teleseismic body waves (up to approximately 15 Hz))" (GSN ad hoc Design Goals Subcommittee 2002). To help meet this goal, Streckeisen STS-1 seismometers were deployed at 80 GSN stations. Some of the GSN sensors have been deployed for more than 25 years. Several recent studies (Davis et al. 2005; Ekström et al. 2006; Davis and Berger 2007) have examined the question of overall calibration of the GSN. Ekström et al. (2006) indicated that a number of sites showed anomalous responses and suggested a gradual decay in the sensitivity. We have investigated the anomalous responses at several GSN sites. At least some of the problems observed by Ekström et al. (2006) may be attributed to humid air leaking into the feedback electronics of the STS-1 seismometers, which produces lower than normal sensitivities near the long-period corner of the instrument (360 seconds period). It appears that even though the feedback electronics boxes are designed to be sealed, water vapor can penetrate their interior after they have been exposed to highly humid seismometer vault air for extended periods. Highly humid air was also found to be present inside some STS-1 bell-jars (especially horizontal instruments) after loss of vacuum, resulting in corrosion and leakage between electrical conductors in connectors.

Conceptual Design and Architecture of Mars Exploration Rover (MER) for Seismic Experiments Over Martian Surfaces

NASA Astrophysics Data System (ADS)

Garg, Akshay; Singh, Amit

2012-07-01

Keywords: MER, Mars, Rover, Seismometer Mars has been a subject of human interest for exploration missions for quite some time now. Both rover as well as orbiter missions have been employed to suit mission objectives. Rovers have been preferentially deployed for close range reconnaissance and detailed experimentation with highest accuracy. However, it is essential to strike a balance between the chosen science objectives and the rover operations as a whole. The objective of this proposed mechanism is to design a vehicle (MER) to carry out seismic studies over Martian surface. The conceptual design consists of three units i.e. Mother Rover as a Surrogate (Carrier) and Baby Rovers (two) as seeders for several MEMS-based accelerometer / seismometer units (Nodes). Mother Rover can carry these Baby Rovers, having individual power supply with solar cells and with individual data transmission capabilities, to suitable sites such as Chasma associated with Valles Marineris, Craters or Sand Dunes. Mother rover deploys these rovers in two opposite direction and these rovers follow a triangulation pattern to study shock waves generated through firing tungsten carbide shells into the ground. Till the time of active experiments Mother Rover would act as a guiding unit to control spatial spread of detection instruments. After active shock experimentation, the babies can still act as passive seismometer units to study and record passive shocks from thermal quakes, impact cratering & landslides. Further other experiments / payloads (XPS / GAP / APXS) can also be carried by Mother Rover. Secondary power system consisting of batteries can also be utilized for carrying out further experiments over shallow valley surfaces. The whole arrangement is conceptually expected to increase the accuracy of measurements (through concurrent readings) and prolong life cycle of overall experimentation. The proposed rover can be customised according to the associated scientific objectives and further needs.

BOREAS HYD-1 Volumetric Soil Moisture Data

NASA Technical Reports Server (NTRS)

Cuenca, Richard H.; Kelly, Shaun F.; Stangel, David E.; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Smith, David E. (Technical Monitor)

2000-01-01

The Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-1 team made measurements of volumetric soil moisture at the Southern Study Area (SSA) and Northern Study Area (NSA) tower flux sites in 1994 and at selected tower flux sites in 1995-97. Different methods were used to collect these measurements, including neutron probe and manual and automated Time Domain Reflectometry (TDR). In 1994, the measurements were made every other day at the NSA-OJP (Old Jack Pine), NSA-YJP (Young Jack Pine), NSA-OBS (Old Black Spruce), NSA-Fen, SSA-OJP, SSA-YJP, SSA-Fen, SSA-YA (Young Aspen), and SSA-OBS sites. In 1995-97, when automated equipment was deployed at NSA-OJP, NSA-YJP, NSA-OBS, SSA-OBS, and SSA-OA (Old Aspen), the measurements were made as often as every hour. The data are stored in tabular ASCII files. The volumetric soil moisture data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

Small aperture seismic arrays for studying planetary interiors and seismicity

NASA Astrophysics Data System (ADS)

Schmerr, N. C.; Lekic, V.; Fouch, M. J.; Panning, M. P.; Siegler, M.; Weber, R. C.

2017-12-01

Seismic arrays are a powerful tool for understanding the interior structure and seismicity across objects in the Solar System. Given the operational constraints of ground-based lander investigations, a small aperture seismic array can provide many of the benefits of a larger-scale network, but does not necessitate a global deployment of instrumentation. Here we define a small aperture array as a deployment of multiple seismometers, with a separation between instruments of 1-1000 meters. For example, small aperture seismic arrays have been deployed on the Moon during the Apollo program, the Active Seismic Experiments of Apollo 14 and 16, and the Lunar Seismic Profiling Experiment deployed by the Apollo 17 astronauts. Both were high frequency geophone arrays with spacing of 50 meters that provided information on the layering and velocity structure of the uppermost kilometer of the lunar crust. Ideally such arrays would consist of instruments that are 3-axis short period or broadband seismometers. The instruments must have a sampling rate and frequency range sensitivity capable of distinguishing between waves arriving at each station in the array. Both terrestrial analogs and the data retrieved from the Apollo arrays demonstrate the efficacy of this approach. Future opportunities exist for deployment of seismic arrays on Europa, asteroids, and other objects throughout the Solar System. Here we will present both observational data and 3-D synthetic modeling results that reveal the sensing requirements and the primary advantages of a small aperture seismic array over single station approach. For example, at the smallest apertures of < 1 m, we constrain that sampling rates must exceed 500 Hz and instrument sensitivity must extend to 100 Hz or greater. Such advantages include the improved ability to resolve the location of the sources near the array through detection of backazimuth and differential timing between stations, determination of the small-scale structure (layering, scattering bodies, density and velocity variations) in the vicinity of the array, as well as the ability to improve the signal to noise ratio of distant body waves by additive methods such as stacking and velocity-slowness analysis. These results will inform future missions on the surfaces of objects throughout the Solar System.

Geophysical survey of the Eggvin Bank and Logi Ridge - Greenland Sea

NASA Astrophysics Data System (ADS)

Breivik, A. J.; Mjelde, R.; Rai, A. K.; Frassetto, A.

2012-12-01

The northern Greenland Sea has a number of features associated with excess volcanism. These include the Jan Mayen island, the Jan Mayen Plateau north of, and the Eggvin Bank west of Jan Mayen, and the Vesteris Seamount far to the north. In the summer of 2011, we colleced an Ocean Bottom Seismometer (OBS) profile across the Eggvin Bank, returning four good data sets. We also collected single-channel reflection seismic (SCS) data along the OBS line. The profile crosses the transform part of the West Jan Mayen Fracture Zone (WJMFZ), which connects seafloor spreading between the Kolbeinsey and Mohn ridges. Between the WJMFZ and the Vesteris Seamount there is a narrow ridge 170-180 km long, ending in a few seamounts in the east. It disturbs the magnetic seafloor anomalies, and has no conjugate on the Norwegian margin. It thus appears to be younger than the Eocene seafloor it lies on. Trend and position points to Traill Ø in East Greenland, which had magmatism at ~36 Ma. We name it the Logi Ridge after Norse mythology, where Logi is the master of fire, brother of Aegir, master of the sea. We have collected five SCS profiles across this ridge in order to study the surrounding sedimentation pattern. We also collected gravity and magnetic data along all profiles. Initial results show two flat-topped seamounts on the Eggvin Bank, and a flat-topped Logi Ridge, indicating that these have been at sealevel. The sedimentary strata show recent vertical movement north of the WJMFZ near the Jan Mayen Plateau, and compression around the Logi Ridge. Sailing line of R/V Håkon Mosby of Bergen. Survey lines are in bold, and OBS positions are marked by circles.

A Design for an Orbital Assembly Facility for Complex Missions

NASA Astrophysics Data System (ADS)

Feast, S.; Bond, A.

A design is presented for an Operations Base Station (OBS) in low earth orbit that will function as an integral part of a space transportation system, enabling assembly and maintenance of a Cis-Lunar transportation infrastructure and integration of vehicles for other high energy space missions to be carried out. Construction of the OBS assumes the use of the SKYLON Single-Stage-to-Orbit (SSTO) spaceplane, which imposes design and assembly constraints due to its payload mass limits and payload bay dimensions. It is assumed that the space transport infrastructure and high mission energy vehicles would also make use of SKYLON to deploy standard transport equipment and stages bound by these same constraints. The OBS is therefore a highly modular arrangement, incorporating some of these other vehicle system elements in its layout design. Architecturally, the facilities of the OBS are centred around the Assembly Dock which is in the form of a large cylindrical spaceframe structure with two large doors on either end incorporating a skin of aluminised Mylar to enclose the dock. Longitudinal rails provide internal tether attachments to anchor vehicles and components while manipulators are used for the handling and assembling of vehicle structures. The exterior of the OBS houses the habitation modules for workforce and vehicle crews along with propellant farms and other operational facilities.

Seismic Structure of the Oceanic Plate Entering the Central Part of the Japan Trench Obtained from Ocean-Bottom Seismic Data

NASA Astrophysics Data System (ADS)

Ohira, A.; Kodaira, S.; Fujie, G.; No, T.; Nakamura, Y.; Miura, S.

2017-12-01

In trench-outer rise regions, the normal faults develop due to the bending of the incoming plate, which cause numerous normal-faulting earthquakes and systematic structural variations toward trenches. In addition to the effects on the bend-related normal fault, structural variations which are interpreted to be attributed to pseudofaults, a fracture zone, and petit-spot volcanic activities are observed in the oceanic plate entering the central part of the Japan Trench, off Miyagi. In May-June 2017, to understand detail structural variations and systematic structural changes of the oceanic plate toward the trench, we conducted an active-source seismic survey off Miyagi using R/V Kaimei, a new research vessel of JAMSTEC. Along a 100 km-long seismic profile which is approximately perpendicular to the trench axis, we deployed 40 ocean-bottom seismometers at intervals of 2 km and fired a large airgun array (total volume 10,600 cubic inches) with 100 m shooting intervals. Multi-channel seismic reflection data were also collected along the profile. On OBS records we observed refractions from the sedimentary layer and the oceanic crust (Pg), wide-angle reflections from the crust-mantle boundary (PmP), and refractions from the uppermost mantle (Pn). Pg is typically observed clearly at near offsets (approximately 20 km) but it highly attenuates at far offsets (> 20 km). A triplication of Pg-PmP-Pn with strong amplitudes is observed at ranges from 30 km to 60 km offsets. Pn is typically weak and its apparent velocity is approximately 8 km/sec. High attenuation of Pg and weak Pn may indicate the complex crustal structure related to petit-spot volcanic activities and/or a fracture zone, which are recognized in bathymetry data around the profile.

RoMi: Refraction Microtremor Using Rotational Seismometers

NASA Astrophysics Data System (ADS)

Clark, B.; Abbott, R. E.; Knox, H. A.; Eimer, M. O.; Hart, D. M.; Skaggs, J.; Denning, J. T.

2013-12-01

We present the results of a shallow shear-wave velocity study that utilized both traditional geophones and a newly developed rotational seismometer (Applied Technology Associates ARS-16). We used Refraction Microtremor (ReMi), a method developed by John N. Louie, during processing to determine both Rayleigh and Love wave dispersion curves using both vertical and horizontal sources. ReMi uses a distance-time (x-t) wavefield transformation technique to image the dispersion curve in slowness-frequency (p-f) space. In the course of the ReMi processing, unwanted P waves are transformed into p-f space. As rotational seismometers are insensitive to P waves, they should prove to be superior sensors for Love wave studies, as those P waves would not interfere with interpretation of the p-f wavefield. Our results show that despite having one-fifth the geophone signal-to-noise ratio in the distance-time wavefield, the ARS-16 produced superior results in the p-f wavefield. Specifically, we found increases of up to 50% in ReMi spectral ratio along the dispersion curve. This implies that as more quiet and sensitive rotational sensors are developed, deploying rotational seismometers instead of traditional sensors will yield significantly better results. This will ultimately improve shallow shear-wave velocity resolution, which is vital for calculating seismic hazard. This data was collected at Sandia National Laboratories' Facility for Analysis, Calibration, and Testing (FACT) located in Albuquerque, NM. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Towards seismic waveform inversion of long-offset Ocean-Bottom Seismic data for deep crustal imaging offshore Western Australia

NASA Astrophysics Data System (ADS)

Monnier, S.; Lumley, D. E.; Kamei, R.; Goncharov, A.; Shragge, J. C.

2016-12-01

Ocean Bottom Seismic datasets have become increasingly used in recent years to develop high-resolution, wavelength-scale P-wave velocity models of the lithosphere from waveform inversion, due to their recording of long-offset transmitted phases. New OBS surveys evolve towards novel acquisition geometries involving longer offsets (several hundreds of km), broader frequency content (1-100 Hz), while receiver sampling often remains sparse (several km). Therefore, it is critical to assess the effects of such geometries on the eventual success and resolution of waveform inversion velocity models. In this study, we investigate the feasibility of waveform inversion on the Bart 2D OBS profile acquired offshore Western Australia, to investigate regional crustal and Moho structures. The dataset features 14 broadband seismometers (0.01-100 Hz) from AuScope's national OBS fleet, offsets in excess of 280 km, and a sparse receiver sampling (18 km). We perform our analysis in four stages: (1) field data analysis, (2) 2D P-wave velocity model building, synthetic data (3) modelling, and (4) waveform inversion. Data exploration shows high-quality active-source signal down to 2Hz, and usable first arrivals to offsets greater than 100 km. The background velocity model is constructed by combining crustal and Moho information in continental reference models (e.g., AuSREM, AusMoho). These low-resolution studies suggest a crustal thickness of 20-25 km along our seismic line and constitute a starting point for synthetic modelling and inversion. We perform synthetic 2D time-domain modelling to: (1) evaluate the misfit between synthetic and field data within the usable frequency band (2-10 Hz); (2) validate our velocity model; and (3) observe the effects of sparse OBS interval on data quality. Finally, we apply 2D acoustic frequency-domain waveform inversion to the synthetic data to generate velocity model updates. The inverted model is compared to the reference model to investigate the improved crustal resolution and Moho boundary delineation that could be realized using waveform inversion, and to evaluate the effects of the acquisition parameters. The inversion strategies developed through the synthetic tests will help the subsequent inversion of sparse, long-offset OBS field data.

Washington State Play Fairway Analysis - Passive Monitoring of St. Helens Shear Zone for Tomography and Precision Microseismic Event Detection

DOE Data Explorer

Swyer, Michael (ORCID:0000000309776975); Cladouhos, Trenton; Crosbie, Kayla; Ulberg, Carl (ORCID:000000016198809X)

2017-10-03

Data resources were derived from a passive seismic survey of the northern St. Helens Shear Zone on geothermal leases 12-24 km north of Mount St. Helens for phase 2 of the Geothermal Play-Fairway Analysis of Washington State Prospects. A 20 seismic station array of broadband seismometers was deployed with irregular spacing (1-4 km) over an area of 12 km to image seismogenic features and their damage zones in the shallow crust.

First deployment of a Multiparameter Ocean Bottom System in the Mediterranean sea

NASA Astrophysics Data System (ADS)

Hello, Y.; Charvis, P.; Yegikyan, M.; Rivet, D.; Deschamps, A.

2016-12-01

Continuous monitoring of oceans is the next great scientific and technical challenge. Recently several cabled sea bottom observatories were developed in Canada (Neptune), in Japan (DONET) and in France (Antares) for real time monitoring of seismic activity, dynamics of the water column, global environmental changes, observation of marine life, the detection of neutrinos, etc. Nevertheless, these initiatives are costly to install and to maintain and it is unlikely that we can deploy many similar observatories in the near future. Among the most recent alternative we developed a 3-years autonomy system equipped with a Nanometrics Trillium 120 s, a triaxial accelerometer, a differential and an absolute pressure gauge, and a hydrophone. MUG-OBS (Multiparameter Geophysical Ocean Bottom system) is a free falling instrument rated down to 6000 m for the monitoring of geophysical signals (earthquakes, submarine landslides, other transient signals, …). The major innovation is that it is possible to recover the data any time on demand (regularly every 6-months or after a crisis) using one of the 6 data-shuttles released from the surface by acoustic command. The MUG-OBS prototype was tested in situ twice for a short period of one week in the bay of Villefranche-sur-mer (French Riviera) in November 2015 and March 2016. During these periods we were lucky to record several teleseismic events with an excellent signal to noise ratio. In September 2016 the instrument will be deployed in the Ligurian sea, 35 miles offshore the city of Nice, for a three-years period, to extend offshore the regional land seismic network. We will present the first seismic signals available from this new instrument. MUG-OBS is a user friendly design and once installed can be maintained by non-specialists to recover data using ship of opportunity. This make it a good challenger to be deployed along the subduction of South America in the frame of the future Subduction Zone Observatory. Such a sea bottom system could also be equipped with other sensors (ADCP, underwater Methane sensor, CO2 flow-through sensor,…) and could be used as a multidisciplinary platform for the environmental monitoring of the deep Ocean.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pierson, Bob; Laughlin, Darren

Under this Department of Energy (DOE) grant, A-Tech Corporation d.b.a. Applied Technology Associates (ATA), seeks to develop a seven-degree-of-freedom (7-DOF) seismic measurement tool for high-temperature geothermal applications. The Rotational-Enabled 7-DOF Seismometer includes a conventional tri-axial accelerometer, a conventional pressure sensor or hydrophone, and a tri-axial rotational sensor. The rotational sensing capability is novel, based upon ATA's innovative research in rotational sensing technologies. The geothermal industry requires tools for high-precision seismic monitoring of crack formation associated with Enhanced Geothermal System (EGS) stimulation activity. Currently, microseismic monitoring is conducted by deploying many seismic tools at different depth levels along a 'string' withinmore » drilled observation wells. Costs per string can be hundreds of thousands of dollars. Processing data from the spatial arrays of linear seismometers allows back-projection of seismic wave states. In contrast, a Rotational-Enabled 7-DOF Seismometer would simultaneously measure p-wave velocity, s-wave velocity, and incident seismic wave direction all from a single point measurement. In addition, the Rotational-Enabled 7-DOF Seismometer will, by its nature, separate p- and s-waves into different data streams, simplifying signal processing and facilitating analysis of seismic source signatures and geological characterization. By adding measurements of three additional degrees-of-freedom at each level and leveraging the information from this new seismic observable, it is likely that an equally accurate picture of subsurface seismic activity could be garnered with fewer levels per hole. The key cost savings would come from better siting of the well due to increased information content and a decrease in the number of confirmation wells drilled, also due to the increase in information per well. Improved seismic tools may also increase knowledge, understanding, and confidence, thus removing some current blocks to feasibility and significantly increasing access to potential geothermal sites. During the Phase 1 effort summarized in this final report, the ATA Team modeled and built two TRL 3 proof-of-concept test units for two competing rotational sensor technologies. The two competing technologies were based on ATA's angular rate and angular displacement measurement technologies; Angular rate: ATA's Magnetohydrodynamic Angular Rate Sensor (Seismic MHD); and Angular displacement: ATA's Low Frequency Improved Torsional Seismometer (LFITS). In order to down-select between these two technologies and formulate a go / no go decision, the ATA Team analyzed and traded scientific performance requirements and market constraints against sensor characteristics and components, acquiring field data where possible to validate the approach and publishing results from these studies of rotational technology capability. Based on the results of Phase 1, the ATA Team finds that the Seismic MHD (SMHD) technology is the best choice for enabling rotational seismometry and significant technical potential exists for micro-seismic monitoring using a downhole 7-DOF device based on the SMHD. Recent technical papers and field data confirm the potential of rotational sensing for seismic mapping, increasing confidence that cost-reduction benefits are achievable for EGS. However, the market for geothermal rotational sensing is small and undeveloped. As a result, this report recommends modifying the Phase 2 plan to focus on prototype development aimed at partnering with early adopters within the geothermal industry and the scientific research community. The highest public benefit will come from development and deployment of a science-grade SMHD rotational seismometer engineered for geothermal downhole conditions and an integrated test tool for downhole measurements at active geothermal test sites.« less

Shear-wave Velocity Structure and Inter-Seismic Strain Accumulation in the Up-Dip Region of the Cascadia Subduction Zone: Similarities to Tohoku?

NASA Astrophysics Data System (ADS)

Collins, J. A.; McGuire, J. J.; Wei, M.

2013-12-01

The up-dip region of subduction zone thrusts is difficult to study using land-based seismic and geodetic networks, yet documenting its ability to store and release elastic strain is critical for understanding the mechanics of great subduction earthquakes and tsunami generation. The 2011 Tohoku earthquake produced extremely large slip in the shallowest portion of the subduction zone beneath a region of the fore-arc that is comprised of extremely low-velocity, unconsolidated sediments [Tsuru et al. JGR 2012]. The influence of the sediment material properties on the co-seismic slip distribution and tsunami generation can be considerable through both the effects on the dynamic wavefield during the rupture [Kozdon and Dunham, BSSA 2012] and potentially the build up of strain during the inter-seismic period. As part of the 2010-2011 SeaJade experiment [Scherwath et al, EOS 2011], we deployed 10 ocean bottom seismographs (OBS) on the continental slope offshore of Vancouver Island in the region of the NEPTUNE Canada observatory. One goal of the experiment is to measure the shear modulus of the sediments lying above the subducting plate using the seafloor compliance technique. Using seafloor acceleration measured by broadband seismometer and seafloor pressure measured by Differential Pressure Gauge (DPG), we estimate the compliance spectrum in the infra-gravity wave band (~0.002-0.04 Hz) at 9 sites following the methodology of Crawford et al. [JGR, 1991]. We calibrated DPG sensitivities using laboratory measurements and by comparing teleseismic Rayleigh arrivals recorded on the seismometer and DPG channels [Webb, pers. comm]. We correct the vertical-component seismometer data for tilt using the procedure of Crawford and Webb [BSSA, 2000], Corrections for the gravitational attraction of the surface gravity waves [Crawford et al., JGR, 1998] are important at frequencies of 0.003-0.006 Hz only. Typically, the coherences are high (>0.7) in the 0.006 to 0.03 Hz range. We invert the measured compliances in this frequency band using a genetic algorithm that solves for the S-wave velocity, P-wave velocity, and density in a layered structure. By including constraints on the Vp distribution from active-source studies, these parameters appear well constrained down to about 4 km depth from our dataset. There is a clear difference in observed compliance values between stations close to the deformation front (~10 km) and those further up the continental slope (~30-40 km) indicating a region of unconsolidated, high-porosity sediment similar to the off-Tohoku region. The low S-wave velocities and high Vp/Vs ratios in the up-dip region correspond to unconsolidated high-porosity sediments. We calculated the effect of this material property contrast on the inter-seismic strain accumulation in the up-dip region of the subduction zone using a finite element model and find that the sediments can increase the amount of inter-seismic strain accumulated in the up-dip region by >100% relative to a homogenous elastic model.

Microseism Source Distribution Observed from Ireland

NASA Astrophysics Data System (ADS)

Craig, David; Bean, Chris; Donne, Sarah; Le Pape, Florian; Möllhoff, Martin

2017-04-01

Ocean generated microseisms (OGM) are recorded globally with similar spectral features observed everywhere. The generation mechanism for OGM and their subsequent propagation to continental regions has led to their use as a proxy for sea-state characteristics. Also many modern seismological methods make use of OGM signals. For example, the Earth's crust and upper mantle can be imaged using ``ambient noise tomography``. For many of these methods an understanding of the source distribution is necessary to properly interpret the results. OGM recorded on near coastal seismometers are known to be related to the local ocean wavefield. However, contributions from more distant sources may also be present. This is significant for studies attempting to use OGM as a proxy for sea-state characteristics such as significant wave height. Ireland has a highly energetic ocean wave climate and is close to one of the major source regions for OGM. This provides an ideal location to study an OGM source region in detail. Here we present the source distribution observed from seismic arrays in Ireland. The region is shown to consist of several individual source areas. These source areas show some frequency dependence and generally occur at or near the continental shelf edge. We also show some preliminary results from an off-shore OBS network to the North-West of Ireland. The OBS network includes instruments on either side of the shelf and should help interpret the array observations.

Continuous seismic monitoring of Nishinoshima volcano, Izu-Ogasawara, by using long-term ocean bottom seismometers

NASA Astrophysics Data System (ADS)

Shinohara, Masanao; Ichihara, Mie; Sakai, Shin'ichi; Yamada, Tomoaki; Takeo, Minoru; Sugioka, Hiroko; Nagaoka, Yutaka; Takagi, Akimichi; Morishita, Taisei; Ono, Tomozo; Nishizawa, Azusa

2017-11-01

Nishinoshima in Izu-Ogasawara started erupting in November 2013, and the island size increased. Continuous monitoring is important for study of the formation process. Since it is difficult to make continuous observations on a remote uninhabited island, we started seismic observations near Nishinoshima using ocean bottom seismometers (OBSs) from February 2015. Our OBSs have a recording period of 1 year, and recovery and re-deployment of OBSs were repeated to make continuous observations. The OBSs were deployed with distances of less than 13 km from the crater. Events with particular characteristics were frequently recorded during the eruption period and are estimated to correlate with the release of plumes from the crater by comparison with temporal on-site records using a video camera and microphones. We estimated the number of events using the amplitude average of records to monitor volcanic activity. There were approximately 1800 detected events per day from February to July 2015. The number started to decrease from July 2015, and reached less than 100 per day in November 2015. The surface activity of the volcano was estimated to have ceased in November 2015. Characteristic events began re-occurring in the middle of April 2017. The number of events reached approximately 1400 events per day at the end of May 2017. Seafloor seismic observations using OBSs are a powerful tool for continuous monitoring of island volcanic activity.[Figure not available: see fulltext.

Studies of earthquakes and microearthquakes using near-field seismic and geodetic observations

NASA Astrophysics Data System (ADS)

O'Toole, Thomas Bartholomew

The Centroid-Moment Tensor (CMT) method allows an optimal point-source description of an earthquake to be recovered from a set of seismic observations, and, for over 30 years, has been routinely applied to determine the location and source mechanism of teleseismically recorded earthquakes. The CMT approach is, however, entirely general: any measurements of seismic displacement fields could, in theory, be used within the CMT inversion formulation, so long as the treatment of the earthquake as a point source is valid for that data. We modify the CMT algorithm to enable a variety of near-field seismic observables to be inverted for the source parameters of an earthquake. The first two data types that we implement are provided by Global Positioning System receivers operating at sampling frequencies of 1,Hz and above. When deployed in the seismic near field, these instruments may be used as long-period-strong-motion seismometers, recording displacement time series that include the static offset. We show that both the displacement waveforms, and static displacements alone, can be used to obtain CMT solutions for moderate-magnitude earthquakes, and that performing analyses using these data may be useful for earthquake early warning. We also investigate using waveform recordings - made by conventional seismometers deployed at the surface, or by geophone arrays placed in boreholes - to determine CMT solutions, and their uncertainties, for microearthquakes induced by hydraulic fracturing. A similar waveform inversion approach could be applied in many other settings where induced seismicity and microseismicity occurs..

Long term seismic observation using ocean bottom seismographs in Marmara Sea, Turkey

NASA Astrophysics Data System (ADS)

Takahashi, N.; Pinar, A.; Kalafat, D.; Yamamoto, Y.; Citak, S.; Comoglu, M.; Çok, Ö.; Ogutcu, Z.; Suvarikli, M.; Tunc, S.; Gurbuz, C.; Ozel, N.; Kaneda, Y.

2015-12-01

The North Anatolian Fault crosses the Marmara Sea with a direction of E-W. There are many large earthquakes repeatedly along the fault with a linkage each other. Due to recent large eastern Aegean earthquake with M6, the Marmara Sea is the "blank zone". Japan and Turkey have a SATREPS collaborative study to clarify the structural characters, construct fault models, simulate the strong motion and tsunami, evaluate these risks with hazard maps and educate disaster prevention for local governments and residents. Our activity is one of the most basic studies, and the objectives are to clarify hypocenter locations, monitor the move, and construct fault models referring seismic/magnetotelluric structures, geodetic nature and trenching works. The target area is from western Marmara Sea to the off Istanbul area along the north Anatolian Fault. We deployed ten Ocean Bottom Seismographs (OBSs) between the Tekirdag Basin and the Central Basin in September, 2014. Then, we added five Japanese OBSs and deployed them at the western end of the Marmara Sea and the eastern Central Basin to extend observed area in March, 2015. The OBS has a three-component velocity sensor with a natural frequency of 4.5 Hz and a hydrophone. Japanese team have clarified seismicity around Japan using the OBS. The magnitude of the detected events is 1.0-1.5. We retrieved all 15 OBSs in July, 2015 and deployed them again on the same locations after data copy and battery maintenance. We started OBS data analysis combined with land stations data. Now we detect events automatically using these data and succeeded detection of over one thousand around the north Anatolian Fault. The tentative results show heterogeneous seismicity. The western and central basins have relative high seismicity and the seismogenic zone becomes thicker rather than previous estimation. Then we will evaluate hypocenter locations with high resolution and discuss the shape of faults in each segment and their linkage.

New OBS network deployment offshore Ireland

NASA Astrophysics Data System (ADS)

Le Pape, Florian; Bean, Chris; Craig, David; Jousset, Philippe; Horan, Clare; Hogg, Colin; Donne, Sarah; McCann, Hannah; Möllhoff, Martin; Kirk, Henning; Ploetz, Aline

2016-04-01

With the presence of the stormy NE Atlantic, Ireland is ideally located to investigate further our understanding of ocean generated microseisms and use noise correlation methods to develop seismic imaging in marine environments as well as time-lapse monitoring. In order to study the microseismic activity offshore Ireland, 10 Broad Band Ocean Bottom Seismographs (OBSs) units including hydrophones have been deployed in January 2016 across the shelf offshore Donegal and out into the Rockall Trough. This survey represents the first Broadband passive study in this part of the NE Atlantic. The instruments will be recovered in August 2016 providing 8 months worth of data to study microseisms but also the offshore seismic activity in the area. One of the main goal of the survey is to investigate the spatial and temporal distributions of dominant microseism source regions, close to the microseism sources. Additionally we will study the coupling of seismic and acoustic signals at the sea bed and its evolution in both the deep water and continental shelf areas. Furthermore, the survey also aims to investigate further the relationship between sea state conditions (e.g. wave height, period), seafloor pressure variations and seismic data recorded on both land and seafloor. Finally, the deployed OBS network is also the first ever attempt to closely monitor local offshore earthquakes in Ireland. Ireland seismicity although relatively low can reduce slope stability and poses the possibility of triggering large offshore landslides and local tsunamis.

Analysis of the signals recorded by a single OBS/H near the active Longqi hydrothermal vent at the ultraslow spreading Southwest Indian Ridge (49°39´E)

NASA Astrophysics Data System (ADS)

Liu, Y.; Tao, C.; Cai, L.; Qiu, L.

2016-12-01

We developed a long-period seismic monitoring experiment near the active Longqi hydrothermal vent from January to April during the Chinese cruise DY115-34 in 2014. During the 102-day experiment, more than 2,000 seismic signals recorded by a single Ocean bottom Seismometer with Hydrophone (OBS/H) are associated with tectonic activity and magma migration in the hydrothermal field. We classified these signals into four typical classes based on their time-frequency characteristics: 1. more than1800 volcano-tectonic microearthquakes (VTMs) with clear onset of P and S phases, Ts-Tp delay time less than 2 s and small local magnitude; 2. 3 regional earthquakes used to determinate sensor orientation; 3. about a hundred short duration events (SDEs) whose have several narrow peaks in frequency range and high amplitude with an exponential decaying coda in seismograms; 4. several special acoustic signals that have the similar feature in waveform recorded by seismometers and hydrophone, with uncertain of generated by biological or geological activity. Analysis of signals based on its feature: First, located the 1549 VTMs with high signal to noise ratio (SNR) by the single station location (SSL) method based on polarization analysis, the results shows that hypocenters mainly beneath the axial valley ridge (AVR) and extended to upper mantle with depth of 15 km, it indicates magma is still active now beneath the AVR in the Longqi field. Second, activities of earthquakes have a certain rule, during the first 6 days, there is an active period with 21.6 events per day, After a long quiet period of 78 days (3.4 events per day), a larger scale and a longer duration of the earthquakes activity is coming with 79.7 events per day. This reflects the law of intermittent magmatic and hydrothermal activity in the Longqi field. Moreover, complex frequencies characteristics of SDEs ascribed to clusters of some monochromatic waves around different frequencies suggest that SDEs are the combination of harmonic wave resonated in full-filled pipes and cracks associated with fluid driven. Above all, we make a conclusion that the Longqi hydrothermal field is in the stage of magmatism in the magmato-tectonic cycle, with intense magmatic and hydrothermal activity intermittently follow certain rules.

3D tomographic seismic imaging of the southern rupture barrier of the great Sumatra-Andaman 2005 earthquake

NASA Astrophysics Data System (ADS)

Vermeesch, P. M.; Henstock, T. J.; Lange, D.; McNeill, L. C.; Barton, P. J.; Tang, G.; Bull, J. M.; Tilmann, F.; Dean, S. M.; Djajadihardja, Y.; Permana, H.

2009-04-01

In 2008 a 3D onshore-offshore controlled-source seismic experiment was carried out in an area of 300 km x 400 km, centered on the southern termination of the great Sumatra-Andaman 2005 earthquake rupture. In the first part of cruise SO198 on R/V Sonne ~10000 airgun shots were fired into an array of 47 Ocean Bottom Seismometers (OBSs). A further ~50000 shots were fired into an array of 10 long-deployment OBSs. All shots were recorded on ~15 seismometers on the islands and more than 20 seismometers along the coast of Sumatra. An initial velocity model has been derived from 70132 first-arrival traveltimes from 45 OBSs, using the First-Arrival Seismic Tomography (FAST) inversion code developed by Zelt and Barton (1998). Root Mean Square traveltime misfit reduces from 1311 ms in the 1D starting model to 81 ms after 20 non-linear iterations. Offsets range between 0 and 265 km, with rays penetrating up to 28 km depth in the final model, hereby imaging the top of the subducting oceanic plate and revealing its complex 3D topography. Ray coverage is still being extended by including first-arrival traveltime picks from the landstations on the coast of Sumatra and the islands and from the 10 long-term deployment OBSs that will be recovered in January. The robustness and resolution of the final 3D model is examined by exploring different starting models, different inversion parameters and by carrying out checkerboard tests and synthetic tests. The resulting crustal 3D velocity model will allow us to explore the nature and physical cause of the rupture barrier of the 2005 great earthquake. Comparison with a similar dataset and subsequent 3D velocity model acquired at the boundary between the 2004 and 2005 earthquakes will provide important insights into the segmentation of the Sumatra subduction zone and the dynamics of its great earthquakes. Zelt, C. A. and P. J. Barton (1998). Three-dimensional seismic refraction tomography: A comparison of two methods applied to data from the Faroe Basin. Journal of Geophysical Research 103: 7187-7210.

Detection of baleen whales on an ocean-bottom seismometer array in the Lau Basin

NASA Astrophysics Data System (ADS)

Brodie, D.; Dunn, R.

2011-12-01

Long-term deployment of ocean-bottom seismometer arrays provides a unique opportunity for identifying and tracking whales in a manner not usually possible in biological studies. Large baleen whales emit low frequency (>5Hz) sounds called 'calls' or 'songs' that can be detected on either the hydrophone or vertical channel of the instrument at distances in excess of 50 km. The calls are distinct to individual species and even geographical groups among species, and are thought to serve a variety of purposes. Distinct repeating calls can be automatically identified using matched-filter processing, and whales can be located in a manner similar to that of earthquakes. Many baleen whale species are endangered, and little is known about their geographic distribution, population dynamics, and basic behaviors. The Lau back-arc basin, a tectonically active, elongated basin bounded by volcanic shallows, lies in the southwestern Pacific Ocean between Fiji and Tonga. Although whales are known to exist around Fiji and Tonga, little is understood about the population dynamics and migration patterns throughout the basin. Twenty-nine broadband ocean-bottom seismometers deployed in the basin recorded data for approximately ten months during the years 2009-2010. To date, four species of whales have been identified in the data: Blue (one call type), Humpback (two call types, including long-lasting 'songs'), Bryde's (one call type), and Fin whales (three call types). Three as-yet-unknown call types have also been identified. After the calls were identified, idealized spectrograms of the known calls were matched against the entire data set using an auto-detection algorithm. The auto-detection output provides the number of calls and times of year when each call type was recorded. Based on the results, whales migrate seasonally through the basin with some overlapping of species. Initial results also indicate that different species of whales are more common in some parts of the basin than others, suggesting preferences in water depth and distance to land. In future work, whales will be tracked through the basin using call localization information to illustrate migration patterns of the various species.

Aftershocks of the India Republic Day Earthquake: the MAEC/ISTAR Temporary Seismograph Network

NASA Astrophysics Data System (ADS)

Bodin, P.; Horton, S.; Johnston, A.; Patterson, G.; Bollwerk, J.; Rydelek, P.; Steiner, G.; McGoldrick, C.; Budhbhatti, K. P.; Shah, R.; Macwan, N.

2001-05-01

The MW=7.7 Republic Day (26 January, 2001) earthquake on the Kachchh in western India initiated a strong sequence of small aftershocks. Seventeen days following the mainshock, we deployed a network of portable digital event recorders as a cooperative project of the Mid America Earthquake Center in the US and the Institute for Scientific and Technological Advanced Research. Our network consisted of 8 event-triggered Kinemetrics K2 seismographs with 6 data channels (3 accelerometer, 3 Mark L-28/3d seismometer) sampled at 200 Hz, and one continuously-recording Guralp CMG40TD broad-band seismometer sampled at 220 Hz. This network was in place for 18 days. Underlying our network deployment was the notion that because of its tectonic and geologic setting the Republic Day earthquake and its aftershocks might have source and/or propagation characteristics common to earthquakes in stable continental plate-interiors rather than those on plate boundaries or within continental mobile belts. Thus, our goals were to provide data that could be used to compare the Republic Day earthquake with other earthquakes. In particular, the objectives of our network deployment were: (1) to characterize the spatial distribution and occurrence rates of aftershocks, (2) to examine source characteristics of the aftershocks (stress-drops, focal mechanisms), (3) to study the effect of deep unconsolidated sediment on wave propagation, and (4) to determine if other faults (notably the Allah Bundh) were simultaneously active. Most of our sites were on Jurassic bedrock, and all were either free-field, or on the floor of light structures built on rock or with a thin soil cover. However, one of our stations was on a section of unconsolidated sediments hundreds of meters thick adjacent to a site that was subjected to shaking-induced sediment liquefaction during the mainshock. The largest aftershock reported by global networks was an MW=5.9 event on January 28, prior to our deployment. The largest aftershock we recorded was MW=5.3. Our network recorded signals from nearly 2000 earthquakes, all on-scale.

BlueSeis3A - performance, laboratory tests and applications

NASA Astrophysics Data System (ADS)

Bernauer, F.; Wassermann, J. M.; de Toldi, E.; Guattari, F.; Ponceau, D.; Ripepe, M.; Igel, H.

2017-12-01

One of the most emerging developments in seismic instrumentation is the application of fiber optic gyroscopes as portable rotational ground motion sensors. In the framework of the European Research Council Project, ROMY (ROtational Motions in seismologY), BlueSeis3A was developed in a collaboration between researchers from Ludwig-Maximilians University of Munich, Germany, and the fiber optic sensors manufacturer iXblue, France. With its high sensitivity (20 nrads-1Hz-1/2) in a broad frequency range (0.001 Hz to 50 Hz) BlueSeis3A opens a variety of applications which were up to now hampered by the lack of such an instrument. In this contribution, we will first present performance characteristics of BlueSeis3A with a focus on timing stability and scale factor linearity. In a second part we demonstrate the benefit of directly measured rotational motion for dynamic tilt correction of measurements made with a classical seismometer. A well known tilt signal was produced with a shake table and recorded simultaneously with a classical seismometer and BlueSeis3A. The seismometer measurement could be improved significantly by subtracting the coherent tilt signal which was measured directly with the rotational motion sensor. As a last part we show the advantage of directly measured rotational motion for applications in civil engineering. Results from a measurement campaign in the Giotto bell tower in the city of Florence, Italy, show the possibility of direct observation of torsional modes by deploying a rotational motion sensor inside the structure.

Significant breakthroughs in monitoring networks of the volcanological and seismological French observatories

NASA Astrophysics Data System (ADS)

lemarchand, A.; Francois, B.; Bouin, M.; Brenguier, F.; Clouard, V.; Di Muro, A.; Ferrazzini, V.; Shapiro, N.; Staudacher, T.; Kowalski, P.; Agrinier, P.

2013-12-01

Others authors: S. Tait (1), D. Amorese (4,1), JB de Chabalier (1), A. Anglade (4,1), P. Kowalski (5,1),the teams in the IPGP Volcanological and Seismological observatories In the last few years, French West Indies observatories, in collaboration with the Seismic Research Center (University of West Indies-Trinidad), have modernized the Lesser Antilles Arc seismic and deformation monitoring network. 16 new permanent stations have been installed to strengthen and expand its detection capabilities. The global network of the IPGP-SRC consortium is now composed of 21 modernized stations, all equipped with broadband seismometers, strong motion sensors, GNSS sensors and satellite communication for real-time data transfer to the observatories of Trinidad (SRC), Guadeloupe (OVSG), Martinique (OVSM). To improve the sensitivity and reduce ambient noise, special efforts were made to enhance the design of the seismic vault and the original Stuttgart shielding (D. Kurrle R. Widmer-Schnidrig, 2005) of the broadband seismometers (240 and 120 sec). This renewed network feeds the Caribbean Tsunami Warning System supported by UNESCO and establishes a monitoring tool that produces high quality data for studying subduction and volcanism interactions in the Lesser Antilles arc. Since 2010, the UnderVolc research program has been an opportunity to reinforce the existing volcanic seismic network of Piton de la Fournaise on La Réunion Island (Indian Ocean). 20 broadband seismometers, 20 short-period sensors, and 26 GNSS receivers now cover the volcano. The program successfully developed many new data treatment tools. They have proven to be well-adapted for monitoring volcanic activity such as the tracking of seismic velocity changes inferred from seismic noise, or the injection of dike and the resulting deformations. This upgrade has now established the monitoring network of La Réunion hot spot to high quality standards which will foster the scientific attractiveness of OVPF-IPGP. During the course of this project, trade-off was chosen to accommodate the broadband seismometer state-of-art installation to unstable substrate made of lava flows. Wifi transmission has been developed for real or near real-time data transmission. Both projects have been an opportunity to migrate the seismic data processing to SeisComP3 with new developed plugins to compute the duration magnitude and locate (modified HYPO71PC ) ever small events such as volcanic ones. The new plugins are integrated in Seiscomp3 releases. Several tools for data management and treatment (Earthworm and WebObs [Beauducel et al., 2004]) are continuously improved. GPS data, real-time and validated seismic data (only broadband) are now available at the IPGP data center.

Lithospheric Shear Velocity Structure of South Island, New Zealand from Rayleigh Wave Tomography of Amphibious Array Data

NASA Astrophysics Data System (ADS)

Ball, J. S.; Sheehan, A. F.; Stachnik, J. C.; Lin, F. C.; Collins, J. A.

2015-12-01

We present the first 3D shear velocity model extending well offshore of New Zealand's South Island, imaging the lithosphere beneath Campbell and Challenger plateaus. Our model is constructed via linearized inversion of both teleseismic (18 -70 s period) and ambient noise-based (8 - 25 s period) Rayleigh wave dispersion measurements. We augment an array of 29 ocean-bottom instruments deployed off the South Island's east and west coasts in 2009-2010 with 28 New Zealand land-based seismometers. The ocean-bottom seismometers and 4 of the land seismometers were part of the Marine Observations of Anisotropy Near Aotearoa (MOANA) experiment, and the remaining land seismometers are from New Zealand's permanent GeoNet array. Major features of our shear wave velocity (Vs) model include a low-velocity (Vs<4.3km/s) body extending to at least 75km depth beneath the Banks and Otago peninsulas, a high-velocity (Vs~4.7km/s) upper mantle anomaly underlying the Southern Alps to a depth of 100km, and discontinuous lithospheric velocity structure between eastern and western Challenger Plateau. Using the 4.5km/s contour as a proxy for the lithosphere-asthenosphere boundary, our model suggests that the lithospheric thickness of Challenger Plateau is substantially greater than that of Campbell Plateau. The high-velocity anomaly we resolve beneath the central South Island exhibits strong spatial correlation with subcrustal earthquake hypocenters along the Alpine Fault (Boese et al., 2013). The ~400km-long low velocity zone we image beneath eastern South Island underlies Cenozoic volcanics and mantle-derived helium observations (Hoke et al., 2000) on the surface. The NE-trending low-velocity zone dividing Challenger Plateau in our model underlies a prominent magnetic discontinuity (Sutherland et al., 1999). The latter feature has been interpreted to represent a pre-Cretaceous crustal boundary, which our results suggest may involve the entire mantle lithosphere.

Optical Mass Displacement Tracking: A simplified field calibration method for the electro-mechanical seismometer.

NASA Astrophysics Data System (ADS)

Burk, D. R.; Mackey, K. G.; Hartse, H. E.

2016-12-01

We have developed a simplified field calibration method for use in seismic networks that still employ the classical electro-mechanical seismometer. Smaller networks may not always have the financial capability to purchase and operate modern, state of the art equipment. Therefore these networks generally operate a modern, low-cost digitizer that is paired to an existing electro-mechanical seismometer. These systems are typically poorly calibrated. Calibration of the station is difficult to estimate because coil loading, digitizer input impedance, and amplifier gain differences vary by station and digitizer model. Therefore, it is necessary to calibrate the station channel as a complete system to take into account all components from instrument, to amplifier, to even the digitizer. Routine calibrations at the smaller networks are not always consistent, because existing calibration techniques require either specialized equipment or significant technical expertise. To improve station data quality at the small network, we developed a calibration method that utilizes open source software and a commonly available laser position sensor. Using a signal generator and a small excitation coil, we force the mass of the instrument to oscillate at various frequencies across its operating range. We then compare the channel voltage output to the laser-measured mass displacement to determine the instrument voltage sensitivity at each frequency point. Using the standard equations of forced motion, a representation of the calibration curve as a function of voltage per unit of ground velocity is calculated. A computer algorithm optimizes the curve and then translates the instrument response into a Seismic Analysis Code (SAC) poles & zeros format. Results have been demonstrated to fall within a few percent of a standard laboratory calibration. This method is an effective and affordable option for networks that employ electro-mechanical seismometers, and it is currently being deployed in regional networks throughout Russia and in Central Asia.

Three-Dimensional Slowness Images of the Upper Crust Beneath the Lucky Strike Hydrothermal Vent Sites

NASA Astrophysics Data System (ADS)

Seher, T.; Crawford, W.; Singh, S.; Canales, J. P.; Combier, V.; Cannat, M.; Carton, H.; Dusunur, D.; Escartin, J.; Miranda, M. J.; Pouillet-Erguy, A.

2005-12-01

In June-July 2005 we carried out the SISMOMAR cruise, as part of the MOMAR project (Monitoring the Mid-Atlantic Ridge). Within this cruise, we conducted a 3D seismic reflection survey over an 18 km km x 3.8 km area covering both the Lucky Strike volcano and hydrothermal vents field. In order to have a full coverage inside the 3D box, shots continued for 2.25 km on either side of the box and extended out to the median valley bounding faults. To complement the streamer measurements 25 Ocean Bottom Seismometers (OBS) were placed in an 18 km x 18 km area. 11 OBS positions lie inside the 3D box and can be used to determine a very detailed image of the 3D velocity structure beneath the Lucky Strike volcano and hydrothermal vents field. For the 3D box a tuned array of 14 air guns (2600 cubic inches) was fired at an interval of 37.5 m for a total of 39 lines. We will present the first results of the OBS measurements near the Lucky Strike volcano. As a first step towards a joint 3D travel time and slowness (the inverse of velocity at turning depth) tomography, we present the 3D slowness function (latitude, longitude, offset), which can be considered as a 3D brute stack velocity image of the sub-surface (c.f. Barton and Edwards, 1999). The presence of fluid in the upper crust due to hydrothermal circulation should appear as a low velocity anomaly beneath the hydrothermal vents. In the next step the OBS measurements will be used to corroborate the reflection images of layer 2A observed in the streamer data for the 3D box. The OBS inside the 3D box recorded turning ray arrivals from the upper crust at a very fine sampling interval (37.5 m x 100 m) over a large azimuth. This provides the unique opportunity for jointly inverting travel time and slowness. Hence the measurements contain information on local gradients and should provide a very detailed velocity model of the subsurface, including information on hydrothermal systems and a possilbe anisotropy (e.g. Cherret and Singh, 1999). References: P. Barton, R. Edwards: Velocity imaging by tau-p transformation, LITHOS Science Report, 1999, 1, 67-75. A. Cherrett, S. Singh: 3D anisotropic models from multi-component data, LITHOS Science Report, 1999, 1, 29-34.

Southern Mariana OBS Experiment and Preliminary Results of Passive-Source Investigations

NASA Astrophysics Data System (ADS)

Le, B. M.; Lin, J.; Yang, T.; Shiyan 3, S. P. O. R.

2017-12-01

The Southern Mariana OBS Experiment (SMOE) was one of the first seismic experiments targeting the deepest part of Earth's surface. During the Phase I experiment in December 2016, an array of OBS instruments were deployed across the Challenger Deep that recorded both active-source and passive-source data. During the Phase II experiment in December 2016-June 2017, passive-source data were recorded. We have retrieved earthquake signals and processed the waveforms from the recorded global, regional and local events, respectively, during the Phase I experiment. Most of the waveforms recorded by the OBS array have fairly good quality with discernible main phases. Rayleigh waves from many earthquakes were analyzed using the frequency-time analysis and their group velocities at different periods were obtained. The dispersion curves from different Rayleigh wave propagating paths would be valuable for inverting the structure of the subducting Pacific and overriding Philippine Sea plates. Furthermore, we applied the ambient noise cross-correlation method and retrieved high-quality coherence surface wave waveforms. With its relatively high frequencies, the surface waves can be used to study the crustal structure of the region. Together with the Phase II data, we expect that this seismic experiment will provide unprecedented constraints on the structure and geodynamic processes of the southern Mariana trench.

Design of an unmanned Martian polar exploration system

NASA Technical Reports Server (NTRS)

Baldwin, Curt; Chitwood, Denny; Demann, Brian; Ducheny, Jordan; Hampton, Richard; Kuhns, Jesse; Mercer, Amy; Newman, Shawn; Patrick, Chris; Polakowski, Tony

1994-01-01

The design of an unmanned Martian polar exploration system is presented. The system elements include subsystems for transportation of material from earth to Mars, study of the Martian north pole, power generation, and communications. Early next century, three Atlas 2AS launch vehicles will be used to insert three Earth-Mars transfer vehicles, or buses, into a low-energy transfer orbit. Capture at Mars will be accomplished by aerobraking into a circular orbit. Each bus contains four landers and a communications satellite. Six of the twelve total landers will be deployed at 60 deg intervals along 80 deg N, and the remaining six landers at 5 deg intervals along 30 deg E from 65 deg N to 90 deg N by a combination of retrorockets and parachutes. The three communications satellites will be deployed at altitudes of 500 km in circular polar orbits that are 120 deg out of phase. These placements maximize the polar coverage of the science and communications subsystems. Each lander contains scientific equipment, two microrovers, power supplies, communications equipment, and a science computer. The lander scientific equipment includes a microweather station, seismometer, thermal probe, x-ray spectrometer, camera, and sounding rockets. One rover, designed for short-range (less than 2 km) excursions from the lander, includes a mass spectrometer for mineral analysis, an auger/borescope system for depth profiling, a deployable thermal probe, and charge coupled device cameras for terrain visualization/navigation. The second rover, designed for longer-range (2-5 km) excursions from the lander, includes radar sounding/mapping equipment, a seismometer, and laser ranging devices. Power for all subsystems is supplied by a combination of solar cells, Ni-H batteries, and radioisotope thermoelectric generators. Communications are sequenced from rovers, sounding rockets, and remote sensors to the lander, then to the satellites, through the Deep Space Network to and from earth.

EarthScope's Transportable Array in Alaska and Western Canada

NASA Astrophysics Data System (ADS)

Enders, M.; Miner, J.; Bierma, R. M.; Busby, R.

2015-12-01

EarthScope's Transportable Array (TA) in Alaska and Canada is an ongoing deployment of 261 high quality broadband seismographs. The Alaska TA is the continuation of the rolling TA/USArray deployment of 400 broadband seismographs in the lower 48 contiguous states and builds on the success of the TA project there. The TA in Alaska and Canada is operated by the IRIS Consortium on behalf of the National Science Foundation as part of the EarthScope program. By Sept 2015, it is anticipated that the TA network in Alaska and Canada will be operating 105 stations. During the summer 2015, TA field crews comprised of IRIS and HTSI station specialists, as well as representatives from our partner agencies the Alaska Earthquake Center and the Alaska Volcano Observatory and engineers from the UNAVCO Plate Boundary Observatory will have completed a total of 36 new station installations. Additionally, we will have completed upgrades at 9 existing Alaska Earthquake Center stations with borehole seismometers and the adoption of an additional 35 existing stations. As the array doubles in Alaska, IRIS continues to collaborate closely with other network operators, universities and research consortia in Alaska and Canada including the Alaska Earthquake Center (AEC), the Alaska Volcano Observatory (AVO), the UNAVCO Plate Boundary Observatory (PBO), the National Tsunami Warning Center (NTWC), Natural Resources Canada (NRCAN), Canadian Hazard Information Service (CHIS), the Yukon Geologic Survey (YGS), the Pacific Geoscience Center of the Geologic Survey, Yukon College and others. During FY14 and FY15 the TA has completed upgrade work at 20 Alaska Earthquake Center stations and 2 AVO stations, TA has co-located borehole seismometers at 5 existing PBO GPS stations to augment the EarthScope observatory. We present an overview of deployment plan and the status through 2015. The performance of new Alaska TA stations including improvements to existing stations is described.

Importance of large-scale bathymetry features on 2011 Tohoku tsunami waveforms through comparison of simulations with the spatially dense ALBACORE OBS array data

NASA Astrophysics Data System (ADS)

Kohler, M. D.; Lynett, P. J.; Legg, M. R.; Weeraratne, D. S.

2012-12-01

In March 2011, a deployment of ocean bottom seismometers (OBSs) off the coast of Southern California recorded the tsunami resulting from the Mw=9.0 Tohoku, Japan earthquake with very high spatial resolution. The ALBACORE (Asthenosphere and Lithosphere Broadband Architecture from the California Offshore Region Experiment) OBS array spanned a region that was 150 km north-south by 400 km east-west, extending into deep open ocean west of the Patton escarpment. In that array, 22 stations with a spacing of 75 km had differential pressure gauges (DPGs) that recorded water pressure waveform data continuously at 50 samples/second. The DPG tsunami records across the entire array show multiple large-amplitude, coherent phases arriving one hour to more than 36 hours after the initial tsunami phase. To determine the source of the large-amplitude coherent phases, gravity ocean wave propagation calculations were carried out for the Pacific Ocean. Simulated pressure waveforms were compared with data for the ALBACORE stations, as well as for the NOAA DART buoys. The linear, non-dispersive shallow-water simulations include bottom frictional effects, and use the USGS NEIC Tohoku slip model and ETOPO2 (two-minute spatial resolution) bathymetry. The predicted travel times of the initial arrivals are found to be less than 1% different from the observed travel times in the southern California ALBACORE DPG data. In order to gauge the effects of large-scale features in Pacific Ocean bathymetry, several large-scale features were individually removed, and simulations were carried out for the modified bathymetry. The removed features include the Emperor Seamount chain, Hawaiian Islands, Oceania, French Polynesia, and the South American coastline. The results show that the removal of these features has an effect on the arrival time of the phases that depends on the feature proximity to the direct path, but their removal does not have a significant effect on the frequency content or phase amplitudes of the waves. The direct paths recorded in Southern California indicate that the tsunami wave did not interfere with distant above-water features such as the Aleutians, but was diffracted around Point Conception in the California coastline and around southern California islands. It is more likely that the scattered phases are the result of wave reflections off the western Japan coastline, or interactions with local structures such as the central-southern California coastline, plateaus beneath the Channel Islands, and the Patton Escarpment.

Spatiotemporal Relationship between Shallow Slow Slip and Repeating Earthquakes in the Northern Hikurangi Subduction Margin, New Zealand

NASA Astrophysics Data System (ADS)

Shaddox, H. R.; Schwartz, S. Y.; Todd, E. K.; Sheehan, A.; Yarce, J.; Nakai, J. S.

2017-12-01

Repeating earthquakes (REs), events with similar waveforms and locations, have been used to estimate aseismic slip-rate variations and their presence has been used as a proxy for slow slip. Here, we look for REs in the area of a well-recorded slow slip event (SSE) using ocean-bottom data from the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS) experiment. The HOBITSS array of absolute pressure gauges (APG) and ocean-bottom seismometers (OBS) was deployed offshore of Gisborne, New Zealand from May 2014 - June 2015 above shallow (<15 km), episodic (every 18-24 months) SSEs in the northern Hikurangi subduction margin. The HOBITSS network recorded a Mw 6.8 SSE in September/October 2014. To find repeating earthquakes associated with the 2014 SSE we apply matched filtering using the HOBITSS catalog and OBS stations. Events are initially located in Antelope (dbgenloc or dblocsat2), relocated with either NonLinLoc or BayesLoc, and then relocated again (where possible) using GrowClust, a relative relocation algorithm that uses both differential travel times and waveform cross-correlations. Events with final locations within 5 km of the plate interface in the area of the SSE ( 70x100 km area, <2-12 km depth) are used as templates (85 total); few of these plate boundary events occur within areas of large slip. We define RE pairs using a minimum average cross-correlation coefficient of 0.95 at 3+ stations. Only one family of REs (2 events) is found within peak slip ( 20 cm at 8 km depth), days before slip conclusion. One family (2 events) is found in the southern portion of slip ( 15 cm at 7 km depth), two weeks after the SSE. All other REs found (10 families, 30 events) are collocated with a subducting seamount at the northeast edge of slip (<10 cm). One of these families contains two events that occur days before slip termination; the remainder occur days to weeks after the SSE. First-motion focal mechanisms are determined for each family and variability is evident between families; these events may be related to a fracture network surrounding the subducting seamount rather than occurring on the plate interface. Overall, we only find REs toward the end and after the well-recorded 2014 SSE. Thus, in some environments REs may not be reliable indicators of shallow SSEs.

MARGATS cruise: investigation of the deep internal structure and the heterogeneous margins of the Demerara plateau reveals a polyphased volcanic history

NASA Astrophysics Data System (ADS)

Graindorge, D.; Museur, T.; Roest, W. R.; Klingelhoefer, F.; Loncke, L.; Basile, C.; Poetisi, E.; Deverchere, J.; Heuret, A.; Jean-Frederic, L.; Perrot, J.

2017-12-01

The MARGATS scientific cruise was carried out from October 20th to November 16th 2016 on board the R/V L'Atalante, offshore Suriname and French Guiana. This cruise is part of a program dedicated to the geological investigation of the continental margin, including the Demerara plateau, following the GUYAPLAC (2003), IGUANES (2013) and DRADEM (2016) cruises. The aim of MARGATS was to image the internal structure of the Demerara plateau and its different margins using coincident deep penetrating wide angle refraction and multi channel reflection seismic (MCS) methods. During the MARGATS experiment 171 OBS deployments were distributed along 4 wide-angle lines. Along each wide-angle line we also recorded coincident MCS data using a 3 km long 480 channel streamer. The dataset was completed by three MCS lines along the eastern part of the Demerara plateau. MCS MAR007 line which is coincident with line OBS MAR-3 was extended on land by 13 land stations deployed along the Maroni River. This line, together with MCS MAR001 and the coincident OBS MAR-1 line reveal the highly homogeneous deep structure of the internal part of the plateau. MCS MAR005 line, which is coincident with OBS MAR-2, MCS MAR006 line coincident with OBS MAR-4, MCS MAR002, MCS MAR003 and MCS MAR004 helps to elucidate the structural complexity of the northern transform margin and the eastern divergent margin of the plateau. These new datasets are highly complementary to the DRADEM dredge results which provide evidence for mid Jurassic volcanic rocks along the plateau and significant vertical displacements along the transform margin. These results allow to interpret the plateau as the remains of a huge jurassic volcanic divergent margin along the Central Atlantic ocean to the west, possibly remobilized during the cretaceous opening of the Equatorial Atlantic ocean as an highly oblique margin to the north and a divergent margin to the east in persistent presence of volcanism. This AGU session will be a great opportunity to present the exceptional quality of the seismic data, after the initial processing steps and how these data are conditioning a new understanding of the Demarara plateau and its margins which implies the hypothetic role of a new hot spot shaping the complex polyphased history of the structure.

Offshore Seismic Observation in the Western Marmara Sea, Turkey

NASA Astrophysics Data System (ADS)

Yamamoto, Y.; Takahashi, N.; Citak, S.; Kalafat, D.; Pinar, A.; Gurbuz, C.; Kaneda, Y.

2014-12-01

The North Anatolian Fault (NAF) extends 1600 km westward from a junction with the East Anatolian Fault at the Karliova Triple Junction in eastern Turkey, across northern Turkey and into the Aegean Sea, accommodating about 25 mm/yr of right-lateral motion between Anatolia and the Eurasian plate. Since 1939, devastating earthquakes with magnitude greater than seven ruptured NAF westward, starting from 1939 Erzincan at the eastern Turkey and including the latest 1999 Izmit-Golcuk and the Duzce earthquakes in the Marmara region. Considering the fault segments ruptured by the May 24th, 2014 Northern Aegean earthquake, the only un-ruptured segments left behind NAF locate beneath the Marmara Sea and those segments keep their mystery due to their underwater location. To clarify the detailed fault geometry beneath the western Marmara Sea, we started to operate a series of ocean bottom seismographic (OBS) observations. As a first step, we deployed 3 pop-up type OBSs on 20th of March 2014 as a trial observation, and recovered them on 18thof June 2014. Although one of the OBSs worked only 6 days from the start of the observation, other two OBSs functioned properly during the whole 3-month observation period. Only 8 earthquakes were reported near the OBS network in 3 months periods according to the Kandilli Observatory and Earthquake Research Institute catalogue. Thus, we first searched for the microearthquakes missing by the land seismic network and estimated their precious location by using the initial 6 days data. We could identify about 50 earthquakes with more than 5 picking data of P and S first arrivals, and half of them located near the NAF. We also tested the hypocenter relocation by combining the land and OBS seismic data for the 8 earthquakes, and found that these earthquakes are located in between 12-24 km depths. Next, we are planning to deploy 10 OBSs from September 2014 to June 2015 as a second step for our observation. At the AGU fall meeting, we will be able to introduce the OBS location of this new observation. These OBS observations are conducted as a part of the "Earthquake and Tsunami Disaster Mitigation in the Marmara Region and Disaster Education in Turkey" project, financially supported by Japan International Cooperation Agency (JICA), Japan Science and Technology Agency (JST), and the Ministry of Development in Turkey.

Multicomponent seismic methods for characterizing gas hydrate occurrences and systems in deep-water Gulf of Mexico

USGS Publications Warehouse

Haines, Seth S.; Lee, Myung W.; Collett, Timothy S.; Hardage, Bob A.

2011-01-01

In-situ characterization and quantification of natural gas hydrate occurrences remain critical research directions, whether for energy resource, drilling hazard, or climate-related studies. Marine multicomponent seismic data provide the full seismic wavefield including partial redundancy, and provide a promising set of approaches for gas hydrate characterization. Numerous authors have demonstrated the possibilities of multicomponent data at study sites around the world. We expand on this work by investigating the utility of very densely spaced (10’s of meters) multicomponent receivers (ocean-bottom cables, OBC, or ocean-bottom seismometers, OBS) for gas hydrate studies in the Gulf of Mexico and elsewhere. Advanced processing techniques provide high-resolution compressional-wave (PP) and converted shearwave (PS) reflection images of shallow stratigraphy, as well as P-wave and S-wave velocity estimates at each receiver position. Reflection impedance estimates can help constrain velocity and density, and thus gas hydrate saturation. Further constraint on velocity can be determined through identification of the critical angle and associated phase reversal in both PP and PS wideangle data. We demonstrate these concepts with examples from OBC data from the northeast Green Canyon area and numerically simulated OBS data that are based on properties of known gas hydrate occurrences in the southeast (deeper water) Green Canyon area. These multicomponent data capabilities can provide a wealth of characterization and quantification information that is difficult to obtain with other geophysical methods.

Nature of the seismic crust at the Aegir Ridge: A downward continuation approach

NASA Astrophysics Data System (ADS)

Rai, Abhishek; Breivik, Asbj|rn; Mjelde, Rolf; Hanan, Barry; Ito, Garrett; Sayit, Kaan; Howell, Sam; Vogt, Peter; Pedersen, Rolf-Birger

2013-04-01

The marine seismic data are influenced by variations in the thickness and velocity of the water column which causes fluctuations in the arrival times of seismic phases. Downward continuation of the ocean-bottom seismometer data are used to remove the contributions of the water column by bring the shot and receiver at a common datum such as the seafloor. Additionally, the downward continuation focus the seismic energy and hence improves the resolution. We apply the downward continuation technique to analyze the OBS data collected along the eastern shoulder of the Aegir Ridge. The Aegir Ridge is an extinct spreading ridge in the North-East Atlantic ocean. Its proximity to the active Iceland hot-spot makes it important for understanding the process of hotspot-ridge interaction during the Oligocene. We present results of an OBS experiment, supported by single channel streamer, gravity and magnetic observations. Usable seismic data from 20 OBSs distributed along ~550 km length of the profile reveal the variations in crustal thickness and seismic velocities. Regional magnetic anomalies show a faster spreading rate towards the north and a slower spreading towards the southern end near the Iceland hotspot during the active period of the ridge. However, the observed and the predicted crustal thickness show an opposite trend. We interpret this anti-correlation between the seafloor spreading rate and the crustal thickness as a result of the interaction between the Iceland hotspot and the Aegir Ridge.

HyBIS - a low cost, multi-purpose, modular vehicle for detailed ocean mapping

NASA Astrophysics Data System (ADS)

Huehnerbach, V.; Murton, B.; Berndt, C.; Garrard, J.; Wollatz-Vogt, M.; Wetzel, G.; Matthiessen, T.

2013-12-01

HyBIS is a low-cost, multi-purpose, highly maneuverable, fibre-optic controlled survey and sampling robotic underwater vehicle (RUV) capable of diving to 6000m. Built in the UK by Hydro-Lek Ltd. in collaboration with the National Oceanography Centre, Southampton, it has proven itself during recent discoveries of the deepest hydrothermal vents in the world, at 5100m deep in the Cayman Trough in the Caribbean and habitat mapping of seamounts in the Atlantic and Indian oceans . The vehicle has a modular design, with the top module being a command and power system that comprises power management, cameras, lights, hydraulics, thrusters and telemetry. The lower module can alternatively be a clam-shell sampling grab, a manipulator-arm and tool sled, a winch for instrument recovery, or an ocean bottom seismometer deployment module. Unlike a conventional ROV, HyBIS does not have any floatation, rather it is suspended by its umbilical cable directly from the ship. The advantage of direct suspension is that HyBIS can recover or deploy a payload of up to 700kg, although this comes at the price of reduced maneuverability compared to a 'normal' ROV. During its four years of service, HyBIS has, so far, accumulated an impressive list of achievements: recording over 450 hours of HD video footage, thousands of HD still images, collected geological, biological samples, as well as fluids and gas from over 40 different sites. It has also recovered two different seabed landers containing scientific equipment worth over £300k, and placed Ocean Bottom Seismometers onto the seafloor.

The Time-Frequency Signatures of Advanced Seismic Signals Generated by Debris Flows

NASA Astrophysics Data System (ADS)

Chu, C. R.; Huang, C. J.; Lin, C. R.; Wang, C. C.; Kuo, B. Y.; Yin, H. Y.

2014-12-01

The seismic monitoring is expected to reveal the process of debris flow from the initial area to alluvial fan, because other field monitoring techniques, such as the video camera and the ultrasonic sensor, are limited by detection range. For this reason, seismic approaches have been used as the detection system of debris flows over the past few decades. The analysis of the signatures of the seismic signals in time and frequency domain can be used to identify the different phases of debris flow. This study dedicates to investigate the different stages of seismic signals due to debris flow, including the advanced signal, the main front, and the decaying tail. Moreover, the characteristics of the advanced signals forward to the approach of main front were discussed for the warning purpose. This study presents a permanent system, composed by two seismometers, deployed along the bank of Ai-Yu-Zi Creek in Nantou County, which is one of the active streams with debris flow in Taiwan. The three axes seismometer with frequency response of 7 sec - 200 Hz was developed by the Institute of Earth Sciences (IES), Academia Sinica for the purpose to detect debris flow. The original idea of replacing the geophone system with the seismometer technique was for catching the advanced signals propagating from the upper reach of the stream before debris flow arrival because of the high sensitivity. Besides, the low frequency seismic waves could be also early detected because of the low attenuation. However, for avoiding other unnecessary ambient vibrations, the sensitivity of seismometer should be lower than the general seismometer for detecting teleseism. Three debris flows with different mean velocities were detected in 2013 and 2014. The typical triangular shape was obviously demonstrated in time series data and the spectrograms of the seismic signals from three events. The frequency analysis showed that enormous debris flow bearing huge boulders would induce low frequency seismic waves. Owing to the less attenuation of low frequency waves, advanced signals mainly ranged between 2 and 10 Hz were detected in several minutes prior to the arrival of the main surge of a debris flow. As the results, the prior time of the advanced signals could be used not only to extend the warning time, but also to identify the initial location of a developing debris flow.

Interferometric imaging of the San Andreas Fault at Parkfield Using a Massive VSP

NASA Astrophysics Data System (ADS)

Chavarria, J.; Goertz, A.; Karrenbach, M.; Paulsson, B.

2006-12-01

The San Andreas Fault Observatory at Depth (SAFOD) has the goal of investigating the physical processes controlling earthquakes in central California at Parkfield. The observatory consists of a deep well, that intersected the San Andreas Fault at seismogenic depths of ~3.2 km, where recurring microearthquake activity takes place. Previous to the drilling of Phase II, that intersected the fault at the end of Summer 2005, a long array of seismometers was deployed in the deeper part of the well to characterize the fault structure and to aid the monitoring activities of the natural seismicity. The Massive VSP array consisted of 80 three component seismometers that were deployed during April and May 2005. During this period of time we recorded active data from 13 explosions used to refine the velocity models that improved the locations of target events. In addition to this, we continuously monitored passive data from the natural earthquake activity in the area that was dominated by the Parkfield 2004 event aftershock sequence. During the recording time of this project we were able to record one of the target earthquakes of the SAFOD project as well as recently discovered non-volcanic tremor. The data recorded by this deep array of seismometers has provided important information to characterize the structure of the fault at scale that is comparable to the scale of the geologic observations. These observations, derived during drilling of the well, consist of cores and cuttings as well as geophysical logs. With the use of the borehole array of seismometers we have been able to directly correlate this lithologic information with seismic phases observed in the VSP data. This has lead to better understanding the nature of the scattering that takes place in this complex fault zone. Seismic reflections in the dataset were analyzed with Kirchhoff imaging methods to determine a partial image of the San Andreas Fault at depth. Due to the low density distribution of sources in the study area the illumination volume is limited but still shows clear signals originating from sub-vertical structures associated to the strands of the San Andreas fault inferred from high resolution earthquake location. The existing Kirchhoff imaging methods have been complemented with the use of interferometric imaging by which we extract the Green's function of the data recorded by the array. This takes place with the use of correlation analysis of both active and passive data resulting in a dataset where each downhole receiver acts as a virtual source. This analysis has provided a refined image of the structure of the San Andreas Fault at seismogenic depths with which a better understanding of the system can be achieved.

OBS development for long term observation in the Marmara Sea, NW Turkey

NASA Astrophysics Data System (ADS)

Takahashi, Narumi; Shimizu, Satoshi; Maekawa, Takuya; Kalafat, Dogan; Pinar, Ali; Citak, Seckin; Kaneda, Yoshiyuki

2015-04-01

We have carried out a collaboration study between Japan and Turkey since 2013, which is one of SATREPS projects, "Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey". The main objective of this project is to reduce risk brought by earthquakes and tsunamis. In particular, the North Anatolian Fault system runs through the Marmara sea and it is expected that the seismic gap exists there according to past seismic studies. The details of seismicity distribution in the Marmara Sea is, however, still insufficient to construct fault model along the active faults. Therefore, we prepare ten ocean bottom seismographs (OBSs) to realize long term observation. We aim to identify size and depth of seismogenic zones using micro seismicity. In addition, we need to cover relative broad area from off-shore Istanbul city to the western end of the Marmara Sea. To clear these conditions, OBS specifications we need are high dynamic range and low instrument noise to observe micro seismicity, low electrical consumption to realize long term observation of over one year, high cost performance to cover the broad area for OBS installation, low cost implementation, and good operability to treat by relatively small number of persons. All items, which are three components velocity sensor, batteries, a recorder, a GPS receiver, a transponder and its transducer to control OBS retrieval, a flasher and a beacon, are installed in the 17 inches glass sphere. The natural frequency of the velocity sensor is 4.5 Hz and the frequency range of our OBS is from 4.5 Hz to 250 Hz. Data sampling is selectable among 100 Hz, 250 Hz and 500 Hz. Because our OBS is deployed by free fall, accuracy of the OBS clock is essentially one of important factors, and it is less than 0.1 ppm. And the resolution of A/D conversion performed on the recorder is 24 bit and we keep the dynamic range of over 135 dB. These data is stored on a semiconductor memory and the capacity is over 300 days with 100 Hz sampling observation. We adopted noncontact charge using lithium ion batteries to reduce implementation cost. And we can charge batteries and transfer stored data without opening glass sphere. All parameters of each OBS are controlled using wireless LAN. In this presentation, we introduce details of OBS development for Japan-Turkey project.

Continuous Shear Wave Signals from around a Subducted Seamount Following 2014 Mw 6.8 Slow-slip Event in the Hikurangi Subduction Margin Offshore New Zealand

NASA Astrophysics Data System (ADS)

Iwasaki, Y.; Mochizuki, K.; Ishise, M.; Todd, E. K.; Schwartz, S. Y.; Henrys, S. A.; Savage, M. K.; Sheehan, A.; Ito, Y.; Wallace, L.; Webb, S. C.; Zal, H. J.; Yamada, T.; Shinohara, M.

2017-12-01

From May 2014 to June 2015 a marine seismic and geodetic experiment was conducted at the Hikurangi subduction margin. During this experiment, a slow-slip event (SSE) with equivalent moment magnitude of Mw 6.8 occurred for two weeks starting in late September 2014, directly beneath the ocean bottom seismometer (OBS) network (Wallace et al., 2016). In this study, we used the continuous waveform data recorded by these OBSs. We calculated a cross correlation coefficient between the two horizontal components and applied a polarization analysis every 10 seconds for 30 second-long OBS waveform records. As a result, we detected the continuous arrival of S-wave signals that appeared to have started in the latter half of the SSE. This continuous signal was identified as tremor and its source location was determined by the envelope cross-correlation method (Todd et al., 2017, in prep). Our result, however, suggests that these signals occur continuously rather than as sporadic individual events, and that they last for more than two weeks. Polarization directions changed at the same time and then remained stable through the two week duration. Such stable polarized directions can only be identified during this period. Our analysis requires fewer OBS than other methods for monitoring such S-wave signals, which may enable us to detect as yet unidentified signals in the Hikurangi margin where seismic attenuation has been shown to be large. The continuous signals with a stable polarization direction were only observed at OBS stations in a limited region, which suggests that the signals were generated near the up-dip edge of the slow slip area and surrounding a subducted seamount. Sources of the continuous signals appear to have migrated from south to north . This observation is consistent with the location of individual tremors identified with envelope cross-correlation methods (Todd et al., 2017, in prep). The slow slip along the plate interface circumvented the subducted seamount (Wallace et al., 2016). By comparing our result with the slip distribution, we can put more constraints on relationship between frictional properties along the plate interface and subducting topographic features such as seamounts. Migration of the sources of the continuous signal may further provide us with information on rupture propagation of the slow slip.

Lesser Antilles Subduction Zone Investigation by a Cluster of Large Seismic Experiments in the Forearc Region

NASA Astrophysics Data System (ADS)

Last, T.

2007-12-01

Thales LAST stands for Lesser Antilles Subduction zone Team which gathers the scientific teams of a cluster of surveys and cruises that have been carried out in 2007 and coordinated under the European Union THALES WAS RIGHT project (Coord. A. Hirn). This cluster is composed by the German cruise TRAIL with the vessel F/S Merian (PI E. Flueh and H. Kopp, IFM-GEOMAR), the French cruise SISMANTILLES 2 with the IFREMER vessel N/O Atalante (PI M. Laigle, IPG Paris and JF. Lebrun, Univ. Antilles Guyane), and French cruise OBSANTILLES with the IRD vessel N/O Antea (PI P. Charvis, Geoazur, Nice, France). During these cruises and surveys, 84 Ocean Bottom 3-components Seismometers (OBS) and 20 Hydrophones (OBHs) have been brought together from several pools (Geoazur, INSU, IPGP, IFM-GEOMAR, AWI,), with up to 30 land stations (CSIC Barcelone, IPG Paris, INSU-RLBM and -LITHOSCOPE) in addition to the permanent onshore arrays of IPGP and SRU. The deployment of all these instruments has been supported principally by ANR Catastrophes Telluriques et Tsunamis (SUBSISMANTI), by the EU SALVADOR Programme of IFM-GEOMAR, as well as by the EU project THALES WAS RIGHT on the Antilles and Hellenic active subductions to which contribute IPGP, Geoazur, IFM-GEOMAR (Germany), ETH Zurich (Switzerland), CSIC Barcelona (Spain), Univ. Trieste (Italy) and NOA Athens (Greece). The main goal of this large seismic investigation effort is the understanding of the behaviour of the seismogenic zone and location of potential source regions of mega-thrust earthquakes. Specific goals are the mapping of the subduction interplate in the range where it may be seismogenic along the Lesser Antilles Arc from Antigua to southern Martinique Islands, as a contribution to identification and localisation in advance of main rupture zones of possible future major earthquakes, and to the search for transient signals of the activity. The forearc region, commonly considered as a proxy to the seismogenic portion of the subduction mega-thrust fault plane, and which is here the main target has been localized along 3 transects to the Arc thanks to a preliminary survey in 2001, the French SISMANTILLES cuise. We will present the first results obtained during these experiments dedicated specifically to image at depth the seismic structure and activity of this region. To image faults at depth and the detailed upper-crustal structure, 3700 km of multi-beam bathymetry and multi-channel reflection seismic profiles have been collected along a grid comprising 7 strike-lines of up to 300 km long and spaced by 15 km and 12 transects of up to 150 km long and spaced by 25 km (SISMANTILLES 2). All these airgun shots dedicated to deep penetration have been recorded by the 84 OBSs and 20 OBHs deployed by the F/S Merian and N/O Atalante on the nodes of this grid of profiles. It will permit to get Vp constraints on the deep forearc region and mantle wedge by wide-angle refraction studies, as well as constraints on the updip and downdip limits of the seismogenic part of the mega-thrust fault plane. Two of these transects have been extended across the whole arc during the TRAIL survey, with up to 50 OBSs deployed along both 240 km long profiles. All these OBSs remained several months beyond the shot experiments for local earthquakes Vp and Vp/Vs tomography. They have been recovered and partly redeployed by N/O Antea during the OBSANTILLES survey. A significant number of those instruments had broadband seismometers, a notable originality in the case of the OBSs to detect low-frequency transient signals.

Lunar Structure from Coda Wave Interferometry

NASA Astrophysics Data System (ADS)

Nunn, Ceri; Igel, Heiner

2017-04-01

As part of the Apollo lunar missions, four seismometers were deployed on the near-side of the Moon between 1969 and 1972, and operated continuously until 1977. There are many difficulties associated with determining lunar structure from these records. As a result, many properties of the moon, such as the thickness, density and porosity of the crust are poorly constrained. This hampers our ability to determine the structure, geochemical composition of the moon, its evolution, and ultimately the evolution of the solar system. We explore the use of coda wave interferometry to reconstruct the near surface structure within the strongly scattering lunar crust.

Military Medics Insight into Providing Womens Health Services

DTIC Science & Technology

2015-12-22

determining a patient’s preference in a provider rather than gender (Buck & Littleton, 2014). Medics, particularly male medics, were keenly aware of...KS, Littleton HL. (2014). Stereotyped beliefs about male and female OB-GYNS: relationship to provider choice and patient satisfaction. Journal of...health care resource during deployment. Male and female IDCs felt obligated to educate women about how to conduct themselves on ship. In a

3D Crustal Structure of the North-Ligurian Margin from Refraction Tomography S. Simon (1), J.-X. Dessa (1), M.-O. Beslier (1), A. Deschamps (1), N. Béthoux (1), S. Solarino (2), E. Eva (2), F. Sage (1), G. Ferretti (3), C. Eva (3), M. Lelièvre (1), and the GROSMarin Team (1)UNS/UPMC/OCA/INSU-CNRS/IRD, Villefranche-sur-Mer, France (ssimon@geoazur.obs-vlfr.fr), (2)INGV/Dip.Te.Ris, Genova, Italia (3) Univ. Genova/Dip.Te.Ris, Genova, Italia

NASA Astrophysics Data System (ADS)

Simon, S.; Dessa, J.; Beslier, M.; Deschamps, A.; Béthoux, N.; Solarino, S.; Eva, E.; Ferretti, G.; Eva, C.; Lelievre, M.

2010-12-01

The GROSMarin experiment, held in 2008, investigates the structures of the seismically active North Ligurian rifted margin. An array of 21 Ocean Bottom Seismometers was deployed offshore a region spanning from Nice to Imperia and recorded seismic refraction shots as well as microseismicity for a duration of more than 5 months. It was extended onland by both the regional French and Italian seismic networks and 13 mobile stations that provided an even density of acquisition on- and offshore. With this programme, we aim at characterizing the main structures of this singular margin and adjacent atypical oceanic crust and thick Alpine foreland. We also seek to detect and locate microseismic events that occur regularly, mostly offshore, and that herald rare large events such as the destructive 1887 Imperia earthquake (Mw 6.5) which is the greatest seismic event in the area since at least four hundred years, and whose source and associated tectonics remain poorly understood. We present and discuss some results of our active first arrival travel time tomography that covers the margin and coastal zone and includes a total of ~185,000 picks. The transition from oceanic to continental domains is clearly evidenced as well as an intermediate zone wherein anomalously high velocities are found at the base of the crust. Velocity structures are not found to evidence significant variations along strike and locally fit some published results of 1D logs.

Spatial Distribution of earthquakes off the coast of Fukushima Two Years after the M9 Earthquake: the Southern Area of the 2011 Tohoku Earthquake Rupture Zone

NASA Astrophysics Data System (ADS)

Yamada, T.; Nakahigashi, K.; Shinohara, M.; Mochizuki, K.; Shiobara, H.

2014-12-01

Huge earthquakes cause vastly stress field change around the rupture zones, and many aftershocks and other related geophysical phenomenon such as geodetic movements have been observed. It is important to figure out the time-spacious distribution during the relaxation process for understanding the giant earthquake cycle. In this study, we pick up the southern rupture area of the 2011 Tohoku earthquake (M9.0). The seismicity rate keeps still high compared with that before the 2011 earthquake. Many studies using ocean bottom seismometers (OBSs) have been doing since soon after the 2011 Tohoku earthquake in order to obtain aftershock activity precisely. Here we show one of the studies at off the coast of Fukushima which is located on the southern part of the rupture area caused by the 2011 Tohoku earthquake. We deployed 4 broadband type OBSs (BBOBSs) and 12 short-period type OBSs (SOBS) in August 2012. Other 4 BBOBSs attached with absolute pressure gauges and 20 SOBSs were added in November 2012. We recovered 36 OBSs including 8 BBOBSs in November 2013. We selected 1,000 events in the vicinity of the OBS network based on a hypocenter catalog published by the Japan Meteorological Agency, and extracted the data after time corrections caused by each internal clock. Each P and S wave arrival times, P wave polarity and maximum amplitude were picked manually on a computer display. We assumed one dimensional velocity structure based on the result from an active source experiment across our network, and applied time corrections every station for removing ambiguity of the assumed structure. Then we adopted a maximum-likelihood estimation technique and calculated the hypocenters. The results show that intensive activity near the Japan Trench can be seen, while there was a quiet seismic zone between the trench zone and landward high activity zone.

Geoazur's contribution in instrumentation to monitor seismic activity of the Earth

NASA Astrophysics Data System (ADS)

Yates, B.; Hello, Y.; Anglade, A.; Desprez, O.; Ogé, A.; Charvis, P.; Deschamps, A.; Galve, A.; Nolet, G.; Sukhovich, A.

2011-12-01

Seismic activity in the earth is mainly located near the tectonic plate boundaries, in the deep ocean (expansion centers) or near their margins (subduction zones). Travel times and waveforms of recorded seismograms can be used to reconstruct the three-dimensional wave speed distribution in the earth with seismic tomography or to image specific boundaries in the deep earth. Because of the lack of permanent sea-bottom seismometers these observation are conducted over short period of time using portable ocean bottom seismometers. Geaozur has a long experience and strong skills in designing and deploying Ocean Bottom Seismometers all over the world. We have developed two types of ocean bottom instruments. The "Hippocampe" for long deployment and "Lady bug" for aftershock monitoring or for fast overlaps during wide angle experiments. Early warning systems for tsunamis and earthquakes have been developed in recent years but these need real time data transmission and direct control of the instrument. We have developed a permanent real time Broad Band instrument installed in the Mediterranean Sea and connected to the Antares Neutrinos telescope. This instrument offers all the advantages of a very heavy and costly installation, such as the ability to do real-time seismology on the seafloor. Such real-time seafloor monitoring is especially important for seismic hazard. Major earthquakes cause human and economic losses directly related to the strong motion of the ground or by induced phenomena such as tsunamis and landslides. Fiber optical cables provide a high-capacity lightweight alternative to traditional copper cables. Three-component sensors analyze permanently the noise signal and detect the events to record. Major events can force the network to transmit data with almost zero lag time. The optical link also allows us to retrieve events at a later date. However, OBSs alone can never provide the density and long term, homogeneous data coverage needed for local and global seismic imaging of the earth. To complete our pool of instruments we have developed a floating underwater robot that can detect seismic P waves from earthquakes at large distances and transmit these data by the Iridium satellite network in Rudics mode. The robot is named MERMAID for `Mobile Earthquake Recording in Marine Areas by Independent Divers'.

Field Testing GEOICE: A Next-Generation Polar Seismometer

NASA Astrophysics Data System (ADS)

Beaudoin, B. C.; Winberry, J. P.; Huerta, A. D.; Chung, P.; Parker, T.; Anderson, K. R.; Bilek, S. L.; Carpenter, P.

2015-12-01

We report on the development of a new NSF MRI-community supported seismic observatory designed for studies in ice-covered regions - the Geophysical Earth Observatory for Ice Covered Environs (GEOICE). This project is motivated by the need to densify and optimize the collection of high-quality seismic data relevant to key solid Earth and cryosphere science questions. The GEOICE instruments and their power and other ancillary systems are being designed to require minimal installation time and logistical load (i.e., size and weight), while maximizing ease-of-use in the field. The system is capable of advanced data handling and telemetry while being able to withstand conditions associated with icy environments, including cold/wet conditions and high-latitude solar limitations. The instrument capability will include a hybrid seismograph pool of broadband and intermediate elements for observation of both long-period signals (e.g, long-period surface waves and slow sources) and intermediate-to-short-period signals (e.g., teleseismic body waves, local seismicity, and impulsive or extended glaciogenic signals).Key features will include a design that integrates the seismometer and digitizer into a single, environmentally and mechanically robust housing; very low power requirements (~1 watt) for the intermediate-band systems; and advanced power systems that optimize battery capacity and operational limits. The envisioned ~100 element GEOICE instruments will nearly double the current polar inventory of stations and will be maintained and supported at the IRIS PASSCAL Instrument Center to ensure full and flexible peer-reviewed community use. Prototype instruments are currently deployed in Antarctica and Alaska, with a larger Antarctic deployment planned for the 2015-2016 season. The results of these field tests will help to refine instrumentation design and lead to the production of robust and capable next-generation seismic sensors.

Crustal structure and fault geometry of the 2010 Haiti earthquake from temporary seismometer deployments

USGS Publications Warehouse

Douilly, Roby; Haase, Jennifer S.; Ellsworth, William L.; Bouin, Marie‐Paule; Calais, Eric; Symithe, Steeve J.; Armbruster, John G.; Mercier de Lépinay, Bernard; Deschamps, Anne; Mildor, Saint‐Louis; Meremonte, Mark E.; Hough, Susan E.

2013-01-01

Haiti has been the locus of a number of large and damaging historical earthquakes. The recent 12 January 2010 Mw 7.0 earthquake affected cities that were largely unprepared, which resulted in tremendous losses. It was initially assumed that the earthquake ruptured the Enriquillo Plantain Garden fault (EPGF), a major active structure in southern Haiti, known from geodetic measurements and its geomorphic expression to be capable of producing M 7 or larger earthquakes. Global Positioning Systems (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data, however, showed that the event ruptured a previously unmapped fault, the Léogâne fault, a north‐dipping oblique transpressional fault located immediately north of the EPGF. Following the earthquake, several groups installed temporary seismic stations to record aftershocks, including ocean‐bottom seismometers on either side of the EPGF. We use data from the complete set of stations deployed after the event, on land and offshore, to relocate all aftershocks from 10 February to 24 June 2010, determine a 1D regional crustal velocity model, and calculate focal mechanisms. The aftershock locations from the combined dataset clearly delineate the Léogâne fault, with a geometry close to that inferred from geodetic data. Its strike and dip closely agree with the global centroid moment tensor solution of the mainshock but with a steeper dip than inferred from previous finite fault inversions. The aftershocks also delineate a structure with shallower southward dip offshore and to the west of the rupture zone, which could indicate triggered seismicity on the offshore Trois Baies reverse fault. We use first‐motion focal mechanisms to clarify the relationship of the fault geometry to the triggered aftershocks.

Earthquake recordings from the 2002 Seattle Seismic Hazard Investigation of Puget Sound (SHIPS), Washington State

USGS Publications Warehouse

Pratt, Thomas L.; Meagher, Karen L.; Brocher, Thomas M.; Yelin, Thomas; Norris, Robert; Hultgrien, Lynn; Barnett, Elizabeth; Weaver, Craig S.

2003-01-01

This report describes seismic data obtained during the fourth Seismic Hazard Investigation of Puget Sound (SHIPS) experiment, termed Seattle SHIPS . The experiment was designed to study the influence of the Seattle sedimentary basin on ground shaking during earthquakes. To accomplish this, we deployed seismometers over the basin to record local earthquakes, quarry blasts, and teleseisms during the period of January 26 to May 27, 2002. We plan to analyze the recordings to compute spectral amplitudes at each site, to determine the variability of ground motions over the basin. During the Seattle SHIPS experiment, seismometers were deployed at 87 sites in a 110-km-long east-west line, three north-south lines, and a grid throughout the Seattle urban area (Figure 1). At each of these sites, an L-22, 2-Hz velocity transducer was installed and connected to a REF TEK Digital Acquisition System (DAS), both provided by the Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL) of the Incorporated Research Institutes for Seismology (IRIS). The instruments were installed on January 26 and 27, and were retrieved gradually between April 18 and May 27. All instruments continuously sampled all three components of motion (velocity) at a sample rate of 50 samples/sec. To ensure accurate computations of amplitude, we calibrated the geophones in situ to obtain the instrument responses. In this report, we discuss the acquisition of these data, we describe the processing and merging of these data into 1-hour long traces and into windowed events, we discuss the geophone calibration process and its results, and we display some of the earthquake recordings.

Studying Fin Whales with Seafloor Seismic Networks

NASA Astrophysics Data System (ADS)

Wilcock, W. S.; Soule, D. C.; Weirathmueller, M.; Thomson, R.

2011-12-01

Baleen whales are found throughout the world's oceans and their welfare captivates the general public. Depending on the species, baleen whales vocalize at frequencies ranging from ~10 Hz to several kilohertz. Passive acoustic studies of whale calls are used to investigate behavior and habitat usage, monitor the recovery of populations from whaling and assess the impacts of anthropogenic sounds. Since airguns are a significant source of sound in the oceans, the research goals of academic seismologists can lead to conflicts with those who advocate for whale conservation while being unwilling to consider the societal benefits of marine geophysical studies. In contrast, studies that monitor earthquakes with ocean bottom seismometers (OBSs) provide an opportunity to enhance studies of baleen whales and improve relationships with environmental advocates. The bandwidth of the typical high-frequency or intermediate-band ocean bottom seismometer overlaps the call frequency of the two largest baleen whale species; blue whales generate sequences of 10- to 20-s-long calls centered at ~16 Hz and fin whales produce long sequences of downswept 1-s-long chirps centered at ~20 Hz. Several studies have demonstrated the potential of OBS networks to monitor calling patterns and determine tracks for fin and blue whales. We will summarize the results from a study to track fin whales near the Endeavour hydrothermal vent fields on the Juan de Fuca Ridge and investigate a potential correlation between the density of whales and enhanced zooplankton found throughout the water column overlying the vent fields. From 2003-2006 an 8-station local seismic network that was designed to monitor hydrothermal earthquakes also recorded ~300,000 fin whale vocalizations, mostly in the fall and winter. Automatic picking and localization techniques that are analogous to those used to analyze earthquakes are employed to determine whale tracks. The tracks are then used to interpret calling patterns in the context of swimming behavior and net migration. Because the fin whale calls are repetitive, they are very amendable to the application of seismic correlation techniques and the double difference location method. While the typical uncertainty for an automatic location within the network is ~500 m, successive calls can be located relative to each other by the double difference method with a precision of ~20 m, which is similar to the length of the whale. As storage capabilities of seafloor instruments increase, OBSs could be made even more useful for marine mammal studies by expanding their upper frequency limit, either by increasing the sampling rate of the hydrophone channel or incorporating a compact standalone hydrophone package on the OBS frame.

Detection of seismic anisotropy using ocean bottom seismometers: a case study from the northern headwall of the Storegga Slide

NASA Astrophysics Data System (ADS)

Exley, R. J. K.; Westbrook, G. K.; Haacke, R. R.; Peacock, S.

2010-10-01

Azimuthal seismic anisotropy has been identified from the analysis of S-waves generated by P to S mode conversion in the Pleistocene sediments that form the northern headwall of the Storegga Slide, which were investigated with a seismic experiment employing a seabed array of ocean-bottom seismometers and a grid of airgun shots. The principal technique used to detect the anisotropy was azimuthal stacking of the radial and transverse horizontal geophone components, after the application of moveout, to show the variations in amplitude, phase and cumulative traveltime effects of S-waves, ultimately providing information that identified the `fast' and `slow' S-wave polarization orientations. Particle-motion analysis was used to corroborate the results and provide further information on the magnitudes of cumulative S-wave splitting. A 2-D ray-traced inversion of the traveltimes of pre-critical P and PS arrivals provided a velocity model from which the variation with depth of Vp, Vs and anisotropy could be compared with lithological and stratigraphic data from a borehole at the centre of the OBS array. Increased anisotropic response was observed to be coincident with high velocity units, which have high mica but low water content and are interpreted to be of glacial origin. The analysis of azimuthal seismic anisotropy shows clear evidence for horizontal transverse isotropy or an orthorhombic symmetry. The distribution in orientations of the fast plane of symmetry is broadly bimodal (E-W and NE-SW) across the OBS array. The E-W group showed correlation with the headwalls of old, buried slides and other faults visible within coherency attributes calculated from an accompanying 3-D seismic data set and with the strike of some of the headwalls of slides shown in multibeam bathymetry. However, the pattern of headwall fractures shown in the bathymetry is complicated and reticulate, and the NE-SW orientation is also well represented. We infer that the cause of the anisotropy is the presence of vertical to sub-vertical, fluid-filled fractures and micro-cracks, partially held open by high pore-fluid pressure. The fracture orientations are controlled primarily by the present-day gravitationally induced down-slope stress, which is mediated by the heterogeneous nature of sub-surface, causing local changes in the orientation of the principal stresses at the margins of incipient or failed slides. The fractures, if connected, are likely to increase vertical permeability within the sediment column significantly, and influence the distribution of gas hydrate within the strata.

Mapping the mantle transition zone beneath the central Mid-Atlantic Ridge using Ps receiver functions.

NASA Astrophysics Data System (ADS)

Agius, M. R.; Rychert, C.; Harmon, N.; Kendall, J. M.

2017-12-01

Determining the mechanisms taking place beneath ridges is important in order to understand how tectonic plates form and interact. Of particular interest is establishing the depth at which these processes originate. Anomalies such as higher temperature within the mantle transition zone may be inferred seismically if present. However, most ridges are found in remote locations beneath the oceans restricting seismologists to use far away land-based seismometers, which in turn limits the imaging resolution. In 2016, 39 broadband ocean-bottom seismometers were deployed across the Mid-Atlantic Ridge, along the Romanche and Chain fracture zones as part of the PI-LAB research project (Passive Imaging of the Lithosphere and Asthenosphere Boundary). The one-year long seismic data is now retrieved and analysed to image the mantle transition zone beneath the ridge. We determine P-to-s (Ps) receiver functions to illuminate the 410- and 660-km depth mantle discontinuities using the extended multitaper deconvolution. The data from ocean-bottom seismometers have tilt and compliance noise corrections and is filtered between 0.05-0.2 Hz to enhance the signal. 51 teleseismic earthquakes generated hundreds of good quality waveforms, which are then migrated to depth in 3-D. The topography at the d410 deepens towards the west of the Romanche and Chain fracture zone by 15 km, whereas the topography of d660 shallows beneath the ridge between the two zones. Transition zone thickness thins from 5 to 20 km. Thermal anomalies determined from temperature relationships with transition zone thickness and depth variations of the d410 and d660 suggests hotter temperatures of about 200 K. Overall, the result suggests mid-ocean ridges may have associated thermal signatures as deep as the transition zone.

Monitoring Unstable Glaciers with Seismic Noise Interferometry

NASA Astrophysics Data System (ADS)

Preiswerk, L. E.; Walter, F.

2016-12-01

Gravity-driven glacier instabilities are a threat to human infrastructure in alpine terrain, and this hazard is likely to increase with future changes in climate. Seismometers have been used previously on hazardous glaciers to monitor the natural englacial seismicity. In some situations, an increase in "icequake" activity may indicate fracture growth and thus an imminent major break-off. However, without independent constraints on unstable volumes, such mere event counting is of little use. A promising new approach to monitor unstable masses in Alpine terrain is coda wave interferometry of ambient noise. While already established in the solid earth, application to glaciers is not straightforward, because the lack of inhomogeneities typically suppresses seismic coda waves in glacier ice. Only glaciers with pervasive crevasses provide enough scattering to generate long codas. This is requirement is likely met for highly dynamic unstable glaciers. Here, we report preliminary results from a temporary 5-station on-ice array of seismometers (corner frequencies: 1 Hz, array aperture: 500m) on Bisgletscher (Switzerland). The seismometers were deployed in shallow boreholes, directly above the unstable tongue of the glacier. In the frequency band 4-12 Hz, we find stable noise cross-correlations, which in principle allows monitoring on a subdaily scale. The origin and the source processes of the ambient noise in these frequencies are however uncertain. As a first step, we evaluate the stability of the sources in order to separate effects of changing source parameters from changes of englacial properties. Since icequakes occurring every few seconds may dominate the noise field, we compare their temporal and spatial occurrences with the cross-correlation functions (stability over time, the asymmetry between causal and acausal parts of the cross-correlation functions) as well as with results from beamforming to assess the influence of these transient events on the noise field.

Discriminating different type waves from pressure and ground motion observation in the seafloor by DONET cabled observation network.

NASA Astrophysics Data System (ADS)

Araki, E.; Kawaguchi, K.; Kaneda, Y.

2011-12-01

We developed and deployed seafloor cabled observatory called "Dense Ocean-floor Network for Earthquake and Tsunamis (DONET)" in the Nankai Trough, south of Japan. The main purpose of the DONET network is to observe large earthquake such as Tonankai earthquake in the deployed seafloor and associate Tsunamis in real-time to help disaster mitigation, and as well to monitor inter-seismic crustal activities such as micro earthquakes, very low frequency earthquakes, and slower crustal deformation. In each DONET seafloor observatory, high-sensitive broadband set of instruments for seismic and seafloor pressure monitoring, consisted from Guralp CMG3T broadband seismometer, Metrozet TSA100S accelerometer, Paroscientific 8B7000-2 pressure gauge, a deep-sea differential pressure gauge, a hydrophone, and a seawater thermometer, are installed. The density of seafloor observatories are 20 observatories distributed in 15-30 km interval which is optimized for monitoring of events in the plate boundary beneath the network. DONET may be regarded as a large-scale, high sensitive high density seismic array for monitoring teleseismic events in the Philippine Sea and the Pacific Ocean. The DONET seafloor observatories are situated in wide range of seafloor depth between 1800m and 4500m, from the seafloor basin about 50 km off Japanese Island through the slope of accerecionary prism to the deep trench axis 150 km off the coast, that may also regarded as a vertical array in the 4.5km thick ocean. This variation of depths helps identify T-phases from the array record. In data analysis, it is necessary to identify propagation mode of each observed wave which may often be mixed together. In our design of DONET observation system, we took care to help identification of seismic phase by obtaining both ground motion and seafloor pressure in the same location. This is simply achieved by combining seafloor pressure gauges and seismometer in a single observatory package, but care was taken to observe both in the similar level of sensitivity and dynamic range in wide frequencies from near DC to over 100 Hz. In the case of DONET, the broadband seismometer and the differential pressure gauge have similar level of sensitivity in 0.005 - 10 Hz, and similarly the accelerometer and the hydrophone cover between 1-100Hz, in total covering most frequencies of our interest, 0.005 Hz to 100 Hz. With both ground motion and seafloor pressure measurement, we may distinguish types of waves relatively easily, and it is also possible to filter particular types of waves from the array dataset to help our data analysis. For example, it has been commonly practiced to distinguish up-going and down-going seismic phases from pressure and ground motion, but this is relatively difficult only with sparse seismometer array. This technique may also be applied to correct teleseismic record with sea surface reflection in receiver function analysis for exploring deep crustal structure.

Evolution of the phase 2 preparation and observation tools at ESO

NASA Astrophysics Data System (ADS)

Dorigo, D.; Amarand, B.; Bierwirth, T.; Jung, Y.; Santos, P.; Sogni, F.; Vera, I.

2012-09-01

Throughout the course of many years of observations at the VLT, the phase 2 software applications supporting the specification, execution and reporting of observations have been continuously improved and refined. Specifically the introduction of astronomical surveys propelled the creation of new tools to express more sophisticated, longer-term observing strategies often consisting of several hundreds of observations. During the execution phase, such survey programs compete with other service and visitor mode observations and a number of constraints have to be considered. In order to maximize telescope utilization and execute all programs in a fair way, new algorithms have been developed to prioritize observable OBs taking into account both current and future constraints (e.g. OB time constraints, technical telescope time) and suggest the next OB to be executed. As a side effect, a higher degree of observation automation enables operators to run telescopes mostly autonomously with little supervision by a support astronomer. We describe the new tools that have been deployed and the iterative and incremental software development process applied to develop them. We present our key software technologies used so far and discuss potential future evolution both in terms of features as well as software technologies.

Lunar Structure from Ambient Noise and Coda Wave Interferometry

NASA Astrophysics Data System (ADS)

Nunn, C.; Igel, H.

2016-12-01

As part of the Apollo lunar missions, four seismometers were deployed on the near-side of the Moon between 1969 and 1972, and operated continuously until 1977. There are many difficulties associated with determining lunar structure from these records. As a result, many properties of the moon, such as the thickness, density and porosity of the crust are poorly constrained. This hampers our ability to determine the structure, geochemical composition of the moon, its evolution, and ultimately the evolution of the solar system. We explore the use of ambient noise and coda wave interferometry to reconstruct the near surface structure within the strongly scattering lunar crust.

Next Generation Qualification: Kinemetrics STS-5A Seismometer Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion John; Slad, George William

2017-10-01

Sandia National Laboratories has tested and evaluated two seismometers, the STS-5A, manufactured by Kinemetrics. These seismometers measure three axes of broadband ground velocity using a UVW configuration with feedback control in a mechanically levelled borehole package. The purpose of the seismometer evaluation was to determine a measured sensitivity, response, self-noise, dynamic range, and self-calibration ability. The Kinemetrics STS-5A seismometers are being evaluated for the U.S. Air Force as part of their Next Generation Qualification effort.

Next Generation Qualification: Nanometrics T120PH Seismometer Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion J.; Slad, George William

2017-10-01

Sandia National Laboratories has tested and evaluated three seismometers, the Trillium 120PH, manufactured by Nanometrics. These seismometers measure broadband ground velocity using a UVW configuration with feedback control in a mechanically levelled borehole package. The purpose of the seismometer evaluation was to determine a measured sensitivity, response, self- noise, dynamic range, and self-calibration ability. The Nanometrics Trillium 120PH seismometers are being evaluated for the U.S. Air Force as part of their Next Generation Qualification effort.

Tracking fin whale calls offshore the Galicia Margin, North East Atlantic Ocean.

PubMed

Gaspà Rebull, Oriol; Díaz Cusí, Jordi; Ruiz Fernández, Mario; Gallart Muset, Josep

2006-10-01

Data recorded during a temporary deployment of ocean bottom seismometers (OBSs) are used in this study to monitor the presence of fin whales around the array. In the summer of 2003, ten OBSs were placed 250 km from the NW coast of Iberia in the Galicia Margin, NE Atlantic Ocean for a period of one month. The recorded data set provided a large variety of signals, including fin whale vocalizations identified by their specific acoustic signature. The use of a dense array of seafloor receivers allowed investigation into the locations and tracks of the signal-generating whales using a seismological hypocentral location code. Individual pulses of different sequences have been chosen to study such tracks. Problems related to the correct identification of pulses, discrimination between direct and multiple arrivals, and the presence of more than one individual have been considered prior to location. Fin calls were concentrated in the last two weeks of the deployment and the locations were spread around the area covered by the array. These results illustrate that, besides its classical seismological aim, deployment of semipermanent seafloor seismic arrays can also provide valuable data for marine mammal behavior studies.

Seismicity and Fault Zone Structure Near the Xinfengjiang Water Reservoir, Guangdong, China

NASA Astrophysics Data System (ADS)

Yang, H.; Sun, X.; He, L.; Wang, S.

2015-12-01

Xingfengjiang Water Reservoir (XWR) was built in 1958 and the first impoundment was conducted in 1959. Immediately following the reservoir impoundment, a series of earthquakes occurred in the vicinity of the XWR, including the 1962 M6.1 earthquake that occurred ~1 km next to the dam. Numerous small earthquakes take place in this region presently, making it one of the most active seismic zones in Guangdong. To investigate the present seismicity and associated fault zone structure, we deployed a temporary seismic network, including a dense linear array across the Ren-Zi-Shi fault southwest to the reservoir. The temporary network is consisted of 42 stations that are operated in the field for more than one month. Because of the mountainous terrain, it is impossible to deploy broadband sensors. Here we use DDV-5 seismometer with a central frequency of 120Hz-5s that is independent on external GPS and battery. During our deployment, numerous earthquakes were recorded. Preliminary results of travel time analysis have shown the characteristic of low velocity fault zone. More detailed analysis, including relocation of earthquakes, ambient noise cross correlation, and modeling body waves, will be presented.

3D Crustal Structure of the North-Ligurian Margin: First Results of the GROSMarin Experiment

NASA Astrophysics Data System (ADS)

Dessa, J.-X.; Lelièvre, M.; Simon, S.; Deschamps, A.; Béthoux, N.; Solarino, S.; Beslier, M.-O.; Sage, F.; Bellier, O.; Courboulex, F.; Klingelhoefer, F.; Eva, E.; Ferretti, G.; Scafidi, D.; Pavan, M.; Eva, C.; Lefeldt, M.; Flueh, E.

2010-05-01

The North-Ligurian rifted margin is singular in that it lies immediately next to the Alpine orogenic arc. It is furthermore seismically active and can experience destructive earthquakes such as in 1887 in the region of Imperia—an event that resulted in a tsunami and more than 600 casualties in spite of a coastal area that was much less densely populated than today. Out of such rare large events, the area undergoes a limited and diffuse seismic activity that can remain undetected and is generally poorly located. This results in a poor knowledge of active structures, especially at sea. Such knowledge is however required towards a quantification of the seismic hazard along the French Riviera and the Ligurian region. To this end, the GROSMarin project was undertaken with a dual objective: (1) to characterize the North-Ligurian margin from a structural standpoint—mode and degree of crustal stretching prior to oceanic accretion, segmentation along strike, subsequent evolution in an orogenic context— and (2) to identify zones of active crustal deformation at sea that are likely to generate earthquakes. The programme is a collaborative work between GeoAzur and Dip.Te.Ris (University of Genova), with some support from INGV, IFM-GEOMAR and IFREMER. It took place from April to October 2008 and consisted in the deployment of 21 ocean-bottom seismometers (OBS) on a grid spanning 50 km along strike and 25 km across, located between Nice, France, and Imperia, Italy, and ranging from mid-slope to the deep basin. This array was extended on land by the permanent stations of the French and Italian regional networks, temporarily densified by 13 portable stations. These instruments recorded the shots of a marine seismic source towed from R/V l'Atalante and were left for more than 5 months for passive surveying. The active part of the programme aims at characterizing the main structures of the margin through crustal 3D tomography; the objective of the passive part is to decrease the detection threshold of marine microseismicity and to reach a precise location of events in order to map active faults. Some of the sea and land instruments were fitted with broadband sensors to allow for teleseismic imaging of deep lithospheric discontinuities. We present the preliminary results of this experiment—in particular a first 3D tomographic model obtained from ~31.500 travel times derived from our recording of active seismic shots by the OBS's. Passive data analysis is being under progress and first relocations have been obtained. These results give an insight into the variability of the crustal structure, both along and across strike.

Active-source 3-D tomography near Nias and Batu Islands, offshore central Sumatra

NASA Astrophysics Data System (ADS)

Karplus, M.; Henstock, T.; McNeill, L. C.; Vermeesch, P. M.; Hall, T. R.; Harmon, N.; Barton, P. J.

2013-12-01

Wide-angle reflection and refraction tomography constrain 3-D lithospheric P-wave velocity structure beneath the central Sumatra subduction zone from Nias Island to Siberut, offshore Indonesia at the southern boundary of the 2005 megathrust earthquake rupture. This area includes the earthquake segment boundary near the Batu Islands where the Investigator Fracture Zone is subducted beneath the Eurasian plate. We report along- and across-strike variations in structure of the downgoing slab and overriding plate. Seismic wide-angle data were collected during cruise SO198-1 in May-June 2008. Air gun shots were recorded by 47 temporary ocean bottom seismometers (OBS) deployed in a roughly 200 km by 190 km area, 10 three-component long-term OBS (with differential pressure gauge), and 52 land stations. First arrival refraction modeling using ray tracing and least squares inversion has yielded a lithospheric P-wave velocity model, best-resolved in the top 25 km. We observe velocities of ~4.5-6 km/s within the accretionary prism, which varies by several km in its depth extent. The forearc basin is underlain by high velocities of ~7-8 km/s as shallow as 8 km depth. This high velocity region is likely older forearc oceanic crust, as seen in Cascadia and near Simeulue, offshore Sumatra. The top of the subducting slab ranges in depth from ~10 km near the trench to ~20 km beneath the prism. The top of the slab dips approximately 4-4.5° towards the NE between the trench and the prism. Earthquake hypocenters show the slab dip steepens significantly NE of the forearc basin. We compare our velocity models with models derived from other regions to the north and south along-strike in the Sumatra Subduction Zone, including the 2004-2005 segment boundary at Simeulue. Multi-channel seismic reflection data show that fault structures and reflectivity change considerably along- and across-strike in the central Sumatra subduction zone. Furthermore, regional earthquake locations indicate rupture segmentation along the plate boundary. The Nias segment in the north ruptured in the 2005 M8.7 earthquake. The weakly-coupled Batu segment experiences sporadic clusters of events near the break in the forearc slope. The offshore forearc west of Siberut is characterized by almost aseismic behavior, reflecting the locked state of the plate interface, which hasn't ruptured since the 1797 M8.6-8.8 earthquake. The subducting Investigator Fracture Zone is believed to act as a barrier for propagation of slip during large ruptures. We compare our velocity model with reflection data and rupture segments to characterize differences in the lower plate, upper plate, and plate boundary properties.

Acoustical and optical backscatter measurements of sediment transport in the 1988 1989 STRESS experiment

NASA Astrophysics Data System (ADS)

Lynch, J. F.; Gross, T. F.; Sherwood, C. R.; Irish, J. D.; Brumley, B. H.

1997-04-01

During the 1988-1989 Sediment Transport Events on Shelves and Slopes (STRESS) experiment, a 1-MHz acoustic backscatter system (ABSS), deployed in 90 m of water off the California coast measured vertical profiles of suspended sediment concentration from 1.5 to (nominally) 26 meters above bottom (m.a.b.). An 8-week-long time series was obtained, showing major sediment transport events (storms) in late December and early January. Comparison of the acoustics measurements from 1.5 m.a.b. are made with optical backscatter system (OBS) concentration estimates lower in the boundary layer (0.25 m.a.b.). Correlations between ABSS and OBS concentration measurements and the boundary layer forcing functions (waves, currents, and their non-linear interaction) provided a variety of insights into the nature of the sediment transport of the STRESS site. Transport rates and integrated transport are seen to be dominated by the largest storm events.

Shallow velocity structure of the Alaska Peninsula subduction zone and implications for controls on seismic behavior

NASA Astrophysics Data System (ADS)

Li, J.; Shillington, D. J.; Becel, A.; Nedimovic, M. R.; Kuehn, H.; Webb, S. C.; Abers, G. A.; Keranen, K. M.; Saffer, D. M.

2014-12-01

Downdip and along-strike variations in the seismic behavior of subduction zone megathrust faults are thought to be strongly controlled by changes in the material properties along the plate boundary. Roughness and hydration of the incoming plate, fluid pressure and lithology in the subducting sediment channel are likely to control the distribution of shallower rupture. Here, we focus on the subduction zone offshore of the Alaska Peninsula. In 2011, the ALEUT program acquired deep penetration multichannel seismic (MCS) reflection and ocean bottom seismometer (OBS) data across the apparently freely sliding Shumagin Gap, the locked Semidi segment that last ruptured in 1938 M8.2 earthquake, and the locked western Kodiak asperity, which ruptured in the 1964 M9.2 earthquake. Seismic reflection data from the ALEUT cruise reveal significant variability in the thickness of sediment on the incoming plate and entering the trench, and the roughness and degree of hydration of the incoming plate. Oceanic crust entering the trench in the Shumagin gap is rugged with extensive faults and only a thin layer of sediment (<0.5 km thick). Farther east in the Semidi segment, the subducting plate has a smoother surface with thicker sediments (~1 km thick) and less faulting/hydration. To better constrain the properties of the accretionary prism and shallow part of the plate boundary, we are undertaking travel time tomography using reflection/refraction phases in OBS and MCS data, and constraints on the interface geometry from MCS images to estimate the detailed shallow velocity structure, with particular focus on properties within the shallow subduction channel. We observe refractions and reflections in OBS data from the shallow part of the subduction zone in both the Shumagin Gap and Semidi segment, including reflections off the top and base of what appears to be a layer of subducting sediment, which can be used for this work. We plan to present initial models of the shallow part of the subduction zone from both segments and discuss comparisons between the two.

New Constraints on Extensional Environments through Analysis of Teleseisms

NASA Astrophysics Data System (ADS)

Eilon, Zachary Cohen

We apply a variety of teleseismic methodologies to investigate the upper mantle structure in extensional environments. Using a body wave dataset collected from a regional deployment in the Woodlark Rift, Papua New Guinea, we image anisotropic velocity structure of a rapidly extending rift on the cusp of continental breakup. In the process, we develop a technique for azimuthal anisotropy tomography that is generally applicable to regions of relatively simple anisotropic structure. The Cascadia Initiative ocean bottom seismometer (OBS) deployment provides coverage of an entire oceanic plate in unprecedented detail; we measure attenuation and velocities of teleseisms to characterize the temperature and melt structure from ridge to trench. Our study of shear wave splitting reveals strong azimuthal anisotropy within the Woodlark Rift with fairly uniform fast directions parallel to extension. This observation differs markedly from other continental rifts and resembles the pattern seen at mid-ocean ridges. This phenomenon is best explained by extension-related strain causing preferential alignment of mantle olivine. We develop a simple relationship that links total extension to predicted splitting, and show that it explains the apparent dichotomy in rifts' anisotropy. Finite frequency tomography using a dataset of teleseismic P- and S-wave differential travel times reveals the upper mantle velocity structure of the Woodlark Rift. A well developed slow rift axis extending >250 km along strike from the adjacent seafloor spreading centers demonstrates the removal of mantle lithosphere prior to complete crustal breakup. We argue that the majority of this rift is melt-poor, in agreement with geochemical results. A large temperature gradient arises from the juxtaposition of upwelled axial asthenosphere with a previously unidentified cold structure north of the rift that hosts well located intermediate depth earthquakes. Localization of upper mantle extension is apparent from the velocity structure of the rift axis and may result from the presence of water following recent subduction. In order to resolve potential tradeoffs between anisotropy and velocity gradients, we develop a novel technique for the joint inversion of Delta VS and strength of azimuthal anisotropy using teleseismic direct S-waves. This approach exploits the natural geometry of the regional tectonics and the relative consistency of observed splits; the imposed orthogonality of anisotropic structure takes care of the non-commutative nature of multi-layer splitting. Our tomographic models reveal the breakup of continental lithosphere in the anisotropy signal, as pre-existing fabric breaks apart and is replaced by upwelling asthenosphere that simultaneously advects and accrues an extension-related fabric. Accounting for anisotropy removes apparent noise in isotropic travel times and clarifies the velocity model. Taken together, our results paint a detailed and consistent picture of a highly extended continental rift. Finally, we collect a dataset of differential travel time (delta T) and attenuation (Deltat*) measurements of P- and S-waves recorded on OBS stations that span the Juan de Fuca and Gorda plates. We observe large gradients in Delta t*, with values as high as 2.0 s for S-waves at the ridge axes. Such high values of differential attenuation are not compatible with a purely thermal control, nor are they consistent with focusing effects. We assert that melt, grainsize, and water enhance anelastic effects beneath the ridge. The combination of attenuation and velocity measurements enables us to place quantitative constraints on the properties of the upper mantle in the vicinity of the spreading axis.

Cloud Computing Services for Seismic Networks

NASA Astrophysics Data System (ADS)

Olson, Michael

This thesis describes a compositional framework for developing situation awareness applications: applications that provide ongoing information about a user's changing environment. The thesis describes how the framework is used to develop a situation awareness application for earthquakes. The applications are implemented as Cloud computing services connected to sensors and actuators. The architecture and design of the Cloud services are described and measurements of performance metrics are provided. The thesis includes results of experiments on earthquake monitoring conducted over a year. The applications developed by the framework are (1) the CSN---the Community Seismic Network---which uses relatively low-cost sensors deployed by members of the community, and (2) SAF---the Situation Awareness Framework---which integrates data from multiple sources, including the CSN, CISN---the California Integrated Seismic Network, a network consisting of high-quality seismometers deployed carefully by professionals in the CISN organization and spread across Southern California---and prototypes of multi-sensor platforms that include carbon monoxide, methane, dust and radiation sensors.

Micro-seismic earthquakes characteristics at natural and exploited hydrothermal systems in West Java, Indonesia

NASA Astrophysics Data System (ADS)

Jousset, P. G.; Jaya, M. S.; Sule, R.; Diningrat, W.; Gassner, A.; Akbar, F.; Ryannugroho, R.; Hendryana, A.; Kusnadi, Y.; Syahbana, D.; Nugraha, A. D.; Umar, M.; Indrinanto, Y.; Erbas, K.

2013-12-01

The assessment of geothermal resources requires the understanding of the structure and the dynamics of geothermal reservoirs. We deployed a multidisciplinary geophysical network around geothermal areas in the south of Bandung, West Java, Indonesia. The first deployment included a network of 30 broadband and 4 short-period seismic stations with Güralp and Trillium sensors (0.008 - 100 Hz) since October 2012. In a second step, we extended the network in June 2013 with 16 short-period (1 Hz) seismometers. We describe the set-up of the seismic networks and discuss first observations and results. The co-existence of a large variety of intense surface manifestations like geysers, hot-steaming grounds, hot water pools, and active volcanoes suggest an intimate coupling between volcanic, tectonic and hydrothermal processes in this area. Preliminary location of earthquakes is performed using a non-linear algorithm, which allows us to define at least 3 seismic clusters. We discuss this seismic pattern within the geothermal fields.

Initial observations from seismometers frozen into a borehole through the McMurdo Ice Shelf.

NASA Astrophysics Data System (ADS)

Prior, David; Eccles, Jennifer; Cooper, Joanna; Craw, Lisa; van Haastrecht, Laurine; Hamish Bowman, M.; Stevens, Craig; Gamble Rosevear, Madi; Hulbe, Christina; Gorman, Andrew; Horgan, Huw; Pyne, Alex

2017-04-01

A seismometer cable with two, three-component seismometers was frozen into a hot water borehole through the McMurdo Ice Shelf at Windless Bight in late December 2016. The seismometers are at 39m and 189m depth. The upper seismometer lies just below the firn-ice transition ( 37m) and very close to sea level ( 38m). The lower seismometer is positioned 30m above the base of the ice shelf ( 222m). The seismometers froze in within 40 (upper) to 60 (lower) hours of the last reaming operation. The temperature evolution during freezing is complicated, particularly for the lower seismometer. The complications are interpreted as the result of brine expulsion and brine pocket migration. We conducted an active source experiment using the frozen-in seismometers together with a surface seismometer and four lines of geophones radiating from the borehole, at 45-degree angles, to a distance of 240m. Sources included a traditional hammer and surface plate, two types of hammer activated surface shear wave sources (for hard and soft surfaces) and a hammer activated borehole source. The frozen-in seismometers show excellent separation of P - wave and S - wave arrivals for all sources, particularly on the lower seismometer. The surface shear sources give clearer separation of arrivals on the vertical and horizontal components. For some source to receiver geometries the surface shear sources give no P - wave arrival on the horizontal seismometer components and a very strong S - wave arrival that is partitioned between the horizontal components in correspondence with the source orientation. The borehole source (at 3 to 10m in the firn) also gives clearer separation of P - wave and S - wave arrivals compared to a surface hammer and plate. The frozen-in seismometers were also used to listen for natural events in the ice. Comparing the same events recorded at the surface and at depth, the latter are much less noisy than the former, leading to more clear interpretation. As in the active source experiments, P-wave and S-wave arrivals are clear and the partitioning onto different components (vertical and horizontal) is very clear. Using seismology to interpret the physical properties of ice masses is dependent on quality data. The patterns of anisotropy related to ice crystallographic preferred orientations (CPOs) are particularly rich for S - waves and the ability to measure S - wave velocities and shear wave splitting is of particular importance in using seismology to constrain CPOs. Our initial observations suggest that seismometers frozen-in at depth, together with artificial sources with controlled shear wave kinematics have great potential to help us constrain ice CPOs and resultant plastic anisotropy through seismic data.

Frequency band enlargement of the penetrator seismometer and its application to moonquake observation

NASA Astrophysics Data System (ADS)

Yamada, Ryuhei; Nébut, Tanguy; Shiraishi, Hiroaki; Lognonné, Philippe; Kobayashi, Naoki; Tanaka, Satoshi

2015-07-01

Seismic data obtained over a broad frequency range are very useful in investigation of the internal structures of the Earth and other planetary bodies. However, planetary seismic data acquired through the NASA Apollo and Viking programs were obtained only over a very limited frequency range. To obtain effective seismic data over a broader frequency range on planetary surfaces, broadband seismometers suitable for planetary seismology must be developed. In this study, we have designed a new broadband seismometer based on a short-period seismometer whose resonant frequency is 1 Hz for future geophysical missions. The seismometer is of an electromagnetic type, light weight, small size and has good shock-durability, making it suitable for being loaded onto a penetrator, which is a small, hard-landing probe developed in the LUNAR-A Project, a previous canceled mission. We modified the short-period seismometer so as to have a flat frequency response above about 0.1 Hz and the detection limit could be lowered to cover frequencies below the frequency. This enlargement of the frequency band will allow us to investigate moonquakes for lower frequency components in which waveforms are less distorted because strong scattering due to fractured structures near the lunar surface is likely to be suppressed. The modification was achieved simply by connecting a feedback circuit to the seismometer, without making any mechanical changes to the short-period sensor. We have confirmed that the broadband seismometer exhibits the frequency response as designed and allows us to observe long-period components of small ground motions. Methods to improve the performance of the broadband seismometer from the current design are also discussed. These developments should promise to increase the opportunity for application of this small and tough seismometer in various planetary seismological missions.

P-Wave and S-Wave Velocity Structure of Submarine Landslide Associated With Gas Hydrate Layer on Frontal Ridge of Northern Cascadia Margin

NASA Astrophysics Data System (ADS)

He, T.; Lu, H.; Yelisetti, S.; Spence, G.

2015-12-01

The submarine landslide associated with gas hydrate is a potential risk for environment and engineering projects, and thus from long time ago it has been a hot topic of hydrate research. The study target is Slipstream submarine landslide, one of the slope failures observed on the frontal ridges of the Northern Cascadia accretionary margin off Vancouver Island. The previous studies indicated a possible connection between this submarine landslide feature and gas hydrate, whose occurrence is indicated by a prominent bottom-simulating reflector (BSR), at a depth of ~265-275 m beneath the seafloor (mbsf). The OBS (Ocean Bottom Seismometer) data collected during SeaJade (Seafloor Earthquake Array - Japan Canada Cascadia Experiment) project were used to derive the subseafloor velocity structure for both P- and S-wave using travel times picked from refraction and reflection events. The P-wave velocity structure above the BSR showed anomalous high velocities of about 2.0 km/s at shallow depths of 100 mbsf, closely matching the estimated depth of the glide plane (100 ± 10 m). Forward modelling of S-waves was carried out using the data from the OBS horizontal components. The S-wave velocities, interpreted in conjunction with the P-wave results, provide the key constraints on the gas hydrate distribution within the pores. The hydrate distribution in the pores is important for determining concentrations, and also for determining the frame strength which is critical for controlling slope stability of steep frontal ridges. The increase in S-wave velocity suggests that the hydrate is distributed as part of the load-bearing matrix to increase the rigidity of the sediment.

The exploration technology and application of sea surface wave

NASA Astrophysics Data System (ADS)

Wang, Y.

2016-12-01

In order to investigate the seismic velocity structure of the shallow sediments in the Bohai Sea of China, we conduct a shear-wave velocity inversion of the surface wave dispersion data from a survey of 12 ocean bottom seismometers (OBS) and 377 shots of a 9000 inch3 air gun. With OBS station spacing of 5 km and air gun shot spacing of 190 m, high-quality Rayleigh wave data were recorded by the OBSs within 0.4 5 km offset. Rayleigh wave phase velocity dispersion for the fundamental mode and first overtone in the frequency band of 0.9 3.0 Hz were retrieved with the phase-shift method and inverted for the shear-wave velocity structure of the shallow sediments with a damped iterative least-square algorithm. Pseudo 2-D shear-wave velocity profiles with depth to 400 m show coherent features of relatively weak lateral velocity variation. The uncertainty in shear-wave velocity structure was also estimated based on the pseudo 2-D profiles from 6 trial inversions with different initial models, which suggest a velocity uncertainty < 30 m/s for most parts of the 2-D profiles. The layered structure with little lateral variation may be attributable to the continuous sedimentary environment in the Cenozoic sedimentary basin of the Bohai Bay basin. The shear-wave velocity of 200 300 m/s in the top 100 m of the Bohai Sea floor may provide important information for offshore site response studies in earthquake engineering. Furthermore, the very low shear-wave velocity structure (200 700 m/s) down to 400 m depth could produce a significant travel time delay of 1 s in the S wave arrivals, which needs to be considered to avoid serious bias in S wave traveltime tomographic models.

Gas hydrate concentration and characteristics within Hydrate Ridge inferred from multicomponent seismic reflection data

NASA Astrophysics Data System (ADS)

Kumar, Dhananjay; Sen, Mrinal K.; Bangs, Nathan L.

2007-12-01

A seismic experiment composed of streamer and ocean bottom seismometer (OBS) surveys was conducted in the summer of 2002 at southern Hydrate Ridge, offshore Oregon, to map the gas hydrate distribution within the hydrate stability zone. Gas hydrate concentrations within the reservoir can be estimated with P wave velocity (Vp); however, we can further constrain gas hydrate concentrations using S wave velocity (Vs), and use Vs through its relationship to Vp (Vp/Vs) to reveal additional details such as gas hydrate form within the matrix (i.e., hydrate cements the grains, becomes part of the matrix frame or floats in pore space). Both Vp and Vs can be derived simultaneously by inverting multicomponent seismic data. In this study, we use OBS data to estimate seismic velocities where both gas hydrate and free gas are present in the shallow sediments. Once Vp and Vs are estimated, they are simultaneously matched with modeled velocities to estimate the gas hydrate concentration. We model Vp using an equation based on a modification of Wood's equation that incorporates an appropriate rock physics model and Vs using an empirical relation. The gas hydrate concentration is estimated to be up to 7% of the rock volume, or 12% of the pore space. However, Vp and Vs do not always fit the model simultaneously. Vp can vary substantially more than Vs. Thus we conclude that a model, in which higher concentrations of hydrate do not affect shear stiffness, is more appropriate. Results suggest gas hydrates form within the pore space of the sediments and become part of the rock framework in our survey area.

Automatic, Satellite-Linked "Webcams" as a Tool in Ice-Shelf and Iceberg Research.

NASA Astrophysics Data System (ADS)

Ross, R.; Okal, M. H.; Thom, J. E.; Macayeal, D. R.

2004-12-01

Important dynamic events governing the behavior of ice shelves and icebergs are episodic in time and small in scale, making them difficult to observe. Traditional satellite imagery is acquired on a rigid schedule with coarse spatial resolution and this means that collisions between icebergs or the processes which create ice "mélange" that fills detachment rifts leading to ice-shelf calving, to give examples, cannot be readily observed. To overcome the temporal and spatial gaps in traditional remote sensing, we have deployed cameras at locations in Antarctica where research is conducted on the calving and subsequent evolution of icebergs. One camera is located at the edge of iceberg C16 in the Ross Sea, and is positioned to capture visual imagery of collisions between C16 and neighboring B15A. The second camera is located within the anticipated detachment rift of a "nascent" iceberg on the Ross Ice Shelf. The second camera is positioned to capture visual imagery of the rift's propagation and the in-fill of ice mélange, which constrains the mechanical influence of such rifts on the surrounding ice shelf. Both cameras are designed for connection to the internet (hence are referred to as "webcams") and possess variable image qualities and image-control technology. The cameras are also connected to data servers via the Iridium satellite telephone network and produce a daily image that is transmitted to the internet through the Iridium connection. Results of the initial trial deployments will be presented as a means of assessing both the techniques involved and the value of the scientific information acquired by these webcams. In the case of the iceberg webcam, several collisions between B15A and C16 were monitored over the period between January, 2003 and December, 2004. The time-lapse imagery obtained through this period showed giant "push mounds" of damaged firn on the edge and surface of the icebergs within the zones of contact as a consequence of the collisions. The push mounds were subsequently unstable, and calved as small scale ice debris soon after the collision, thereby returning the iceberg edge to a clean, vertical cliff-like appearance. A correlation between the iceberg collision record available from the webcam and data from a seismometer located on C16 is anticipated once the seismometer data is recovered. The webcam associated with the detachment rift of the nascent iceberg on the Ross Ice Shelf is planned to be deployed in early November, 2004. If results are available from this deployment, they too will be discussed.

Current Research at the Endeavour Ridge 2000 Integrated Studies Site

NASA Astrophysics Data System (ADS)

Butterfield, D. A.; Kelley, D. S.; Ridge 2000 Community, R.

2004-12-01

Integrated geophysical, geological, chemical, and biological studies are being conducted on the Endeavour segment with primary support from NSF, the W.M. Keck Foundation, and NSERC (Canada). The research includes a seismic network, physical and chemical sensors, high-precision mapping and time-series sampling. Several research expeditions have taken place at the Endeavour ISS in the past year. In June 2003, an NSF-sponsored cruise with R.V. al T.G.Thompson/ROV al Jason2 installed microbial incubators in drill-holes in the sides of active sulfide chimneys and sampled rocks, fluids, and microbes in the Mothra and Main Endeavour Field (MEF). In July 2003, with al Thompson/Jason2, an NSF-LEXEN project at Baby Bare on Endeavour east flank conducted sampling through seafloor-penetrating probes, plus time-series sampling of fluids, microbes, and rocks at the MEF. In September 2003, with al Thompson/ROV al ROPOS, the Keck Proto-Neptune project installed a seismic network consisting of 1 broadband and 7 short-period seismometers, installation of chemical/physical sensors and time-series samplers for chemistry and microbiology in the MEF and Clam Bed sites, collection of rocks, fluids, animals, and microbes. In May/June 2004, an NSF-sponsored al Atlantis/Alvin cruise recovered sulfide incubators installed in 2003, redeployed a sulfide incubator, mapped MEF and Mothra vent fields with high-resolution Imagenix sonar, sampled fluids from MEF, Mothra, and Clam Bed, recovered year-long time-series fluid and microbial samplers from MEF and Clam Bed, recovered and installed hot vent temperature-resistivity monitors, cleaned up the MEF and deployed new markers at major sulfide structures. In August 2004, there were two MBARI/Keck-sponsored cruises with R.V. al Western Flyer/ROV al Tiburon. The first cruise completed the seismic network with addition of two more broadband seismometers and serviced all 7 short-period seismometers. al Tiburon then performed microbial and chemical investigations at MEF, Mothra, Sasquatch, and Middle Valley, collecting fluid, particle, and animal samples for culture and phylogenetic analysis. al Tiburon continued in late August/September with detailed petrological sampling. A Keck-sponsored al Thompson/ROPOS cruise in September continued work on chemical/physical sensor deployments and time-series chemical and microbial sampling. A graduate student workshop at Friday Harbor beginning October 2004 will analyze the first year of data from the seismic network and begin to correlate seismic activity with hydrothermal activity. The Endeavour ISS is still in a phase of data collection and sensor development, but moving toward data integration.

Imaging of the 3D crustal structure off the Joetsu region in Japan Sea and its implication of the activity of the tectonic zone by using LT-OBSs

NASA Astrophysics Data System (ADS)

Machida, Y.; Shinbo, T.; Shinohara, M.; Yamada, T.; Mochizuki, K.; Kanazawa, T.

2011-12-01

At the eastern margin of the Japan Sea, large earthquakes have been occurred (e.g., 1964 Niigata earthquake, the 1983 Japan Sea earthquake, the 2004 Chuetsu earthquake and the 2007 Chuetsu-oki earthquake) along the Niigata-Kobe Tectonic Zone (NKTZ). The NKTZ is recognized as a region of large strain rate along the Japan Sea coast and in the northern Chubu and Kinki distinct. Among these events, the 2004 Chuetsu earthquake and the 2007 Chuetsu-oki earthquake is triggered by reactivation of pre-existing faults within ancient rift systems by stress loading through a ductile creeping of the weak lower crust (Kato et al., 2008). Because a source region of the 2007 Chuetsu-oki earthquake is distributed under the Japan Sea, aftershock observation using Ocean Bottom Seismometers were carried out (Shinohara et al., 2008). It is necessary to estimate precise aftershock distribution in order to understand the mechanism of earthquake generation. In addition, a seismic refraction survey was carried out to reveal crustal structure in the region (Nakahigashi et al., submitted). They indicated that most of aftershocks were occurred in the upper crust. Because the tectonic zone is thought to be spread in offshore region, it is difficult to understand a precise activity of the tectonic zone from only land-base observations. To compare the seismic activity with the crustal structure in the region is indispensable to understand the stress field in the tectonic zone and the tectonics in the eastern margin of the Japan Sea. In order to investigate a seismic activity in the tectonic zone, 10 Long-Term Ocean Bottom Seismometers (LT-OBS) were deployed from December, 2008, to October, 2009, in the off Joetsu region. First we estimated hypocenters of events using a location program for finding a maximum likelihood solution using a Bayesian approach (Hirata and Matsu'ura, 1987). The velocity structure for the location was modeled from a previous refraction survey conducted in the same region. Foci of over one thousand and two hundreds earthquakes were estimated with high spatial resolution during the observation period. The hypocentral distribution revealed that most of events are occurred within the upper crust. It is consistent with a result of Shinohara et al. (2008). Our precise locations of the events are useful for crustal structure studies. For example, reliability of results from tomographic study is thought to increase by using our precise locations of the events as initial locations of the inversion. We performed a high resolution 3D tomographic analysis and relocation of earthquake applying the double-difference tomography method (Zhang and Thurber, 2003). We can compare the seismic activity with heterogeneity in crust of the tectonic zone off the coast of Joetsu region.

Detecting Moho Boundary under Taiwan with Wide-angle Data by Ray-tracing Method - The TAIGER Project

NASA Astrophysics Data System (ADS)

Kuo, Y. N.; Wang, C.; Okaya, D. A.

2009-12-01

Taiwan is located at the converging boundary of the Eurasian plate and the Philippine Sea plate, and is one of the most rapidly uplifting orogeny in the world. The geological structure is relatively complicated. There exist several models of tectonic collisions from the thin-skinned thrust, the lithospheric collision, to uplifting by buoyancy. The shape of Moho should be a key factor to evaluate these models. In this study, we try to detect the Moho beneath Taiwan using the newly collected wide-angle data from the Taiwan Integrated Geodynamic Research (TAIGER) project. The results could be of help to set up some constrains for the Taiwan tectonics. The TAIGER project is a collaboration between America and Taiwan. The land stations collected two parts of data (land and marine) generated by active sources. The land part was carried out in 2008/2~3, which created 6 kinds of data from explosion sources including: 1) 3 E-W wide-angle reflections of Texans arrays; 2) 2 N-S seismometer arrays; 3) the seismic networks of Central Weather Bureau(CWB) and Institute of Earth Science(IES) over the island; 4) a short array of RT130; 5) 2 short period OBS arrays in the Taiwan Strait; 6) 2 temporary seismic arrays in Fujan, mainland China. The marine part was carried out in 2009/4~6, which provided 4 kinds of data from air-gun sources including: 1) 4 wide-angle refractions of E-W RT130 arrays; 2) 2 N-S seismometer arrays; 3) the CWB network; 4) the broad band array in Taiwan for Seismology(BATS). In this study, we focus on analyzing the wide-angle data, which contain land explosion data, onshore-offshore data, OBS data and mainland data, especially concentrate on the line in the southern Taiwan (Transect T4). We make a summary of the TAIGER project and show several plots of real data and arrivals. A 2D E-W velocity model was constructed from the mainland side to the ocean side about 600 km long using the ray-tracing method with layer-striping technique. The preliminary results are: 1) the distribution of Moho depth is basically getting deeper from the west to the east, but becoming shallower rapidly in the area of Coast Range; 2) the crust thickens to the range of 40 km in the mountain area; 3) the Moho depth is shallower than 30 km in the Peikang High and deeper than 32 km at the coast line of Fujan, no crust bulge in the Taiwan Strait; 4) the structures derived from PmP phase and Pn phase from land explosions and onshore-offshore air-gun shots are highly consistent.

The precision seismometer based on planar electrochemical transducer

NASA Astrophysics Data System (ADS)

Shabalina, A. S.; Krishtop, V. G.

2016-12-01

In this paper we investigate the possibility of applying a planar electrochemical trancducer (ECT) as a sensing element for a precision seismometer with a high inertial mass. The precision seismometer based on simplest planar ECT was manufactured and tested. We investigated the amplitude-frequency and volt-ampere characteristics, self-noise level and the transducer's impedance frequency dependence. One of the key characteristics for the seismometer is the intrinsic noise level, this work focuses on the self-noise level.

Laboratory and field testing of commercial rotational seismometers

USGS Publications Warehouse

Nigbor, R.L.; Evans, J.R.; Hutt, C.R.

2009-01-01

There are a small number of commercially available sensors to measure rotational motion in the frequency and amplitude ranges appropriate for earthquake motions on the ground and in structures. However, the performance of these rotational seismometers has not been rigorously and independently tested and characterized for earthquake monitoring purposes as is done for translational strong- and weak-motion seismometers. Quantities such as sensitivity, frequency response, resolution, and linearity are needed for the understanding of recorded rotational data. To address this need, we, with assistance from colleagues in the United States and Taiwan, have been developing performance test methodologies and equipment for rotational seismometers. In this article the performance testing methodologies are applied to samples of a commonly used commercial rotational seismometer, the eentec model R-1. Several examples were obtained for various test sequences in 2006, 2007, and 2008. Performance testing of these sensors consisted of measuring: (1) sensitivity and frequency response; (2) clip level; (3) self noise and resolution; and (4) cross-axis sensitivity, both rotational and translational. These sensor-specific results will assist in understanding the performance envelope of the R-1 rotational seismometer, and the test methodologies can be applied to other rotational seismometers.

Applying a Hidden Markov Model-Based Event Detection and Classification Algorithm to Apollo Lunar Seismic Data

NASA Astrophysics Data System (ADS)

Knapmeyer-Endrun, B.; Hammer, C.

2014-12-01

The seismometers that the Apollo astronauts deployed on the Moon provide the only recordings of seismic events from any extra-terrestrial body so far. These lunar events are significantly different from ones recorded on Earth, in terms of both signal shape and source processes. Thus they are a valuable test case for any experiment in planetary seismology. In this study, we analyze Apollo 16 data with a single-station event detection and classification algorithm in view of NASA's upcoming InSight mission to Mars. InSight, scheduled for launch in early 2016, has the goal to investigate Mars' internal structure by deploying a seismometer on its surface. As the mission does not feature any orbiter, continuous data will be relayed to Earth at a reduced rate. Full range data will only be available by requesting specific time-windows within a few days after the receipt of the original transmission. We apply a recently introduced algorithm based on hidden Markov models that requires only a single example waveform of each event class for training appropriate models. After constructing the prototypes we detect and classify impacts and deep and shallow moonquakes. Initial results for 1972 (year of station installation with 8 months of data) indicate a high detection rate of over 95% for impacts, of which more than 80% are classified correctly. Deep moonquakes, which occur in large amounts, but often show only very weak signals, are detected with less certainty (~70%). As there is only one weak shallow moonquake covered, results for this event class are not statistically significant. Daily adjustments of the background noise model help to reduce false alarms, which are mainly erroneous deep moonquake detections, by about 25%. The algorithm enables us to classify events that were previously listed in the catalog without classification, and, through the combined use of long period and short period data, identify some unlisted local impacts as well as at least two yet unreported deep moonquakes.

Investigating the seismic signal of elephants: using seismology to mitigate elephant human conflict

NASA Astrophysics Data System (ADS)

Webb, S. J.; Manzi, M.; Naidoo, A.; Raveloson, A.

2015-12-01

Human interactions with wild elephants are often a source of conflict, as elephants invade inhabited lands looking for sustenance. In order to mitigate these interactions, a number of elephant defense systems are under development. These include electric fences, bees and the playback of warning calls recorded from elephants. With the discovery that elephants use seismic signals to communicate (O'Connell-Rodwell et al., 2006, Behav. Ecol. Sociobiol.), it is hoped that seismic signals can also be used to help reduce conflict. Our current research project investigates the spectral content of the elephant seismic signal that travels through the ground using a variety of geophones and seismometers. Our experimental setup used a Geometrics Geode 24 channel seismic system with an array of 24 geophones spaced 1 m apart in an area of compact soil overlying weathered granites. Initially we used 14 Hz vertical geophones. The ground and ambient noise conditions were characterized by recording several hammer shots. These were used to identify the air wave, wind noise, and the direct wave, which had a dominant frequency of ~50 Hz. Several trained elephants that 'rumble' on command were then deployed ~5 m perpendicular to a line of 24 (14 Hz) vertical geophones between the 1 and 10 m geophone positions. We recorded a number of different elephants and configurations, and digitally recorded video for comparison. An additional deployment of 20 (14 Hz) horizontal geophones was also used. For all data, the sample interval was 0.25 ms and the recording length was 16 s as the timing of the rumbles could not be precisely controlled. We were able to identify the airwave due to the elephant's rumble with velocities between 305-310 m/s and the ground seismic signal due to the rumble with frequencies between 20-30 Hz. Our next experiment will include broadband seismometers at a further distance, to more fully characterize the frequency content of the elephant signal.

Polarization Analysis of the September 2005 Northern Cascadia Episodic Tremor and Slip Event

NASA Astrophysics Data System (ADS)

Wech, A. G.; Creager, K. C.

2006-12-01

The region of Northern Cascadia, extending from the Olympic Mountains and Puget Sound to southern Vancouver Island, down-dip of the subduction "locked" zone has repeatedly experienced episodes of slow slip. This episodic slip, observed to take place over a period of two to several weeks, is accompanied by a seismic tremor signal. Based on the average recurrence interval of 14 months, the last episodic tremor and slip (ETS) event was expected to occur in September, 2005. Indeed, it began on September 3. In order to record this event, we deployed an array of 11 three-component seismometers on the northern side of the Olympic Peninsula augmenting Pacific Northwest Seismographic Network stations as well as the first few EarthScope BigFoot stations and Plate Boundary Observatory borehole seismometers. This seismic array was comprised of six short-period and five broadband instruments with average spacings of 500 m and 2200 m respectively. In conjunction with this Earthscope seismic deployment, we also installed a dense network of 29 temporary, continuous GPS stations across the entire Olympic Peninsula to integrate seismic and geodetic observations. Based on past geodetic observations, a dominant assumption for the source of tremor is fault-slip in the direction of subduction, which can be tested using polarization of the seismic tremor. Using waveform cross- correlation to invert for the direction of slowness, we observed the tremor signal to migrate directly under our array. As the source passed beneath the array, tremor polarization stabilized to coincide with the direction of subduction. During a four day period starting September 8, the normalized eigenvalue associated with the dominant linear polarization jumped from ~0.7 to a stable 0.9 value. Also during this time, the polarization azimuth stabilized to a value of 57 +/- 8 degrees, close to the angle of subduction (56 degrees) suggesting that the tremor is caused by slip in the direction of relative plate motion on one or more faults.

Shallow-velocity models at the Kilauea Volcano, Hawaii, determined from array analyses of tremor wavefields

USGS Publications Warehouse

Saccorotti, G.; Chouet, B.; Dawson, P.

2003-01-01

The properties of the surface wavefield at Kilauea Volcano are analysed using data from small-aperture arrays of short-period seismometers deployed in and around the Kilauea caldera. Tremor recordings were obtained during two Japan-US cooperative experiments conducted in 1996 and 1997. The seismometers were deployed in three semi-circular arrays with apertures of 300, 300 and 400 m, and a linear array with length of 1680 m. Data are analysed using a spatio-temporal correlation technique well suited for the study of the stationary stochastic wavefields of Rayleigh and Love waves associated with volcanic activity and scattering sources distributed in and around the summit caldera. Spatial autocorrelation coefficients are obtained as a function of frequency and are inverted for the dispersion characteristics of Rayleigh and Love waves using a grid search that seeks phase velocities for which the L-2 norm between data and forward modelling operators is minimized. Within the caldera, the phase velocities of Rayleigh waves range from 1400 to 1800 m s-1 at 1 Hz down to 300-400 m s-1 at 10 Hz, and the phase velocities of Love waves range from 2600 to 400 m s-1 within the same frequency band. Outside the caldera, Rayleigh wave velocities range from 1800 to 1600 m s-1 at 1 Hz down to 260-360 m s-1 at 10 Hz, and Love wave velocities range from 600 to 150 m s-1 within the same frequency band. The dispersion curves are inverted for velocity structure beneath each array, assuming these dispersions represent the fundamental modes of Rayleigh and Love waves. The velocity structures observed at different array sites are consistent with results from a recent 3-D traveltime tomography of the caldera region, and point to a marked velocity discontinuity associated with the southern caldera boundary.

Initial Results from the 2002 Gulf of California Conjugate Margin Seismic Experiment

NASA Astrophysics Data System (ADS)

Holbrook, S.; Lizarralde, D.; Kent, G.; Harding, A.; Fletcher, J.; Gonzalez-Fernandez, A.; Umhoefer, P.; Axen, G.

2003-04-01

The Gulf of California, which marks the ongoing separation of Baja California from mainland Mexico, is one of the few locales where active continental breakup can be studied along unambiguous flow lines that join clear conjugate margin pairs. In Fall 2002, we conducted an onshore-offshore seismic experiment across the conjugate rifted margins of the Gulf of California in several rift segments. The joint U.S.-Mexico project, sponsored principally by the MARGINS program of the U.S. National Science Foundation, aimed to image crustal structure across conjugate margins of four major basins to determine the modes of extension and the influence of sedimentation and magmatism on breakup. Here we present an overview of the experiment, which was substantially altered at sea due to concerns for marine-mammal safety, and present some preliminary findings. Three flow-line transects were acquired, in the Alarcon Basin, the Guaymas Basin, and between Cabo and Tres Marias Islands. In addition, a fourth transect across the Baja Peninsula was acquired. Data acquired included (1) multichannel seismic reflection data using the R/V Ewing’s 20-gun array and 480-channel, 6-km-long streamer, (2) wide-angle reflection/refraction data recorded on ocean-bottom seismometers, from 206 deployments conducted by the R/V New Horizon, and (3) onshore-offshore data recorded on portable seismometers deployed up to 100 km inland on all transects. Initial results from the experiment include (1) clear evidence for asymmetric basement structure on the conjugate rifted margins and across the active mid-ocean spreading center, of the Guaymas Basin, (2) the suggestion of substantial magmatism in an early failed rift of the Alarcon Basin, and (3) active subduction beneath the margin at the Tres Marias islands. In addition, we will discuss new procedures for mitigating effects on marine mammals that may have a significant impact on future U.S.-sponsored seismic reflection activities.

BASE Flexible Array Preliminary Lithospheric Structure Analysis

NASA Astrophysics Data System (ADS)

Yeck, W. L.; Sheehan, A. F.; Anderson, M. L.; Siddoway, C. S.; Erslev, E.; Harder, S. H.; Miller, K. C.

2009-12-01

The Bighorns Arch Seismic Experiment (BASE) is a Flexible Array experiment integrated with EarthScope. The goal of BASE is to develop a better understanding of how basement-involved foreland arches form and what their link is to plate tectonic processes. To achieve this goal, the crustal structure under the Bighorn Mountain range, Bighorn Basin, and Powder River Basin of northern Wyoming and southern Montana are investigated through the deployment of 35 broadband seismometers, 200 short period seismometers, 1600 “Texan” instruments using active sources and 800 “Texan” instruments monitoring passive sources, together with field structural analysis of brittle structures. The novel combination of these approaches and anticipated simultaneous data inversion will give a detailed structural crustal image of the Bighorn region at all levels of the crust. Four models have been proposed for the formation of the Bighorn foreland arch: subhorizontal detachment within the crust, lithospheric buckling, pure shear lithospheric thickening, and fault blocks defined by lithosphere-penetrating thrust faults. During the summer of 2009, we deployed 35 broadband instruments, which have already recorded several magnitude 7+ teleseismic events. Through P wave receiver function analysis of these 35 stations folded in with many EarthScope Transportable Array stations in the region, we present a preliminary map of the Mohorovicic discontinuity. This crustal map is our first test of how the unique Moho geometries predicted by the four hypothesized models of basement involved arches fit seismic observations for the Bighorn Mountains. In addition, shear-wave splitting analysis for our first few recorded teleseisms helps us determine if strong lithospheric deformation is preserved under the range. These analyses help lead us to our final goal, a complete 4D (3D spatial plus temporal) lithospheric-scale model of arch formation which will advance our understanding of the mechanisms accommodating and driving basement-involved arch formation as well as continental lithospheric rheology.

Teleseismic P-wave tomography of the Sunda-Banda Arc subduction zone

NASA Astrophysics Data System (ADS)

Harris, C. W.; Miller, M. S.; Widiyantoro, S.; Supendi, P.; O'Driscoll, L.; Roosmawati, N.; Porritt, R.

2017-12-01

The Sunda-Banda Arc is the site of multiple ongoing tectonic deformation processes and is perhaps the best example of the transition from subduction of oceanic lithosphere to an active arc-continent collision. Investigating the mantle structure that has resulted from the collision of continental Australia, as well as the concurrent phenomena of continental subduction, slab-rollback, lithospheric tearing, and subduction polarity reversal is possible through seismic tomography. While both regional scale and global tomographic models have previously been constructed to study the tectonics this region, here we use 250 seismic stations that span the length of this convergent margin to invert for P-wave velocity perturbations in the upper mantle. We combine data from a temporary deployment of 30 broadband instruments as part of the NSF-funded Banda Arc Project, along with data from permanent broadband stations maintained by the Meteorological, Climatological, and Geophysical Agency of Indonesia (BMKG) to image mantle structure, in particular the subducted Indo-Australian plate. The BMKG dataset spans 2009-2017 and includes >200 broadband seismometers. The Banda Arc array (network YS) adds coverage and resolution to southeastern Indonesia and Timor-Leste, where few permanent seismometers are located but the Australian continent-Banda Arc collision is most advanced. The preliminary model was computed using 50,000 teleseismic P-wave travel-time residuals and 3D finite frequency sensitivity kernels. Results from the inversion of the combined dataset are presented as well as resolution tests to assess the quality of the model. The velocity model shows an arcuate Sunda-Banda slab with morphological changes along strike that correlate with the tectonic collision. The model also features the double-sided Molucca Sea slab and regions of high velocity below the bottom of the transition zone. The resolution added by the targeted USC deployment is clear when comparing models that use only BMKG data to models that incorporate the YS network as well.

Hydrodynamics Offshore of the North Beach of Indian River Inlet, DE

NASA Astrophysics Data System (ADS)

DiCosmo, N. R.; Puleo, J. A.

2014-12-01

The Indian River Inlet (IRI) on the east coast of Delaware, USA connects the Atlantic Ocean to the Indian River and Rehoboth Bays. Long-term and large-scale net alongshore sediment transport along this portion of coastline is from south to north. The north beach of IRI suffers from severe erosion due to interruption of the alongshore transport and current variability near the inlet. The magnitude of such erosion has increased over the past decade and questions have arisen as to the cause. The goal of this study is to quantify currents and wave patterns and estimate sediment transport rates at the north beach and near the inlet in an effort to determine the causes of persistent erosion. Data were obtained from October 2013 to March 2014 in the form of 3 separate 28-day deployments. Each deployment consisted of 4 proposed deployment sites. Data at each site were collected using a bottom mounted Nortek Aquadopp Acoustic Doppler Current Profiler (ADCP) and 2 Campbell Scientific Optical Backscatter Sensors (OBS). Currents and OBS data were sampled every 120 s. Waves were sampled for approximately 17 minutes at the beginning of every hour. Data analysis from the deployments indicates the presence of several interesting trends in currents that can be linked to the persistent erosion. Current data are filtered to quantify typical current speed and direction for a tidal cycle (peak flood to peak flood) at each deployment site. The typical currents off of the north beach and up to 800 m north of the north jetty are mostly directed southward over the entire tidal cycle. This consistent southward flow implies: 1) there is no flow reversal based on tide, contrary to what might be expected at an inlet adjacent beach, 2) the typical current direction is opposite of the expectations for the known long-term large-scale net alongshore transport and 3) the consistency of this atypical current may be responsible for transporting sediment southward and away from the north beach. Currents and waves will be further analyzed for storm and non-storm conditions in order to more completely quantify the hydrodynamics of the area. Sediment data will also be analyzed in conjunction with the hydrodynamic data in order to better understand the sediment transport process.

Deployment of a seismic array for volcano monitoring during the ongoing submarine eruption at El Hierro, Canary Islands

NASA Astrophysics Data System (ADS)

Abella, R.; Almendros, J.; Carmona, E.; Martin, R.

2012-04-01

On 17 July 2011 there was an important increase of the seismic activity at El Hierro (Canary Islands, Spain). This increase was detected by the Volcano Monitoring Network (Spanish national seismic network) run by the Instituto Geográfico Nacional (IGN). As a consequence, the IGN immediately deployed a dense, complete monitoring network that included seismometers, GPS stations, geochemical equipment, magnetometers, and gravity meters. During the first three months of activity, the seismic network recorded over ten thousand volcano-tectonic earthquakes, with a maximum magnitude of 4.6. On 10 October 2011 an intense volcanic tremor started. It was a monochromatic signal, with variable amplitude and frequency content centered at about 1-2 Hz. The tremor onset was correlated with the initial stages of the submarine eruption that occurred from a vent located south of El Hierro island, near the village of La Restinga. At that point the IGN, in collaboration with the Instituto Andaluz de Geofísica, deployed a seismic array intended for volcanic tremor monitoring and analysis. The seismic array is located about 7 km NW of the submarine vent. It has a 12-channel, 24-bit data acquisition system sampling each channel at 100 sps. The array is composed by 1 three-component and 9 vertical-component seismometers, distributed in a flat area with an aperture of 360 m. The data provided by the seismic array are going to be processed using two different approaches: (1) near-real-time, to produce information that can be useful in the management of the volcanic crisis; and (2) detailed investigations, to study the volcanic tremor characteristics and relate them to the eruption dynamics. At this stage we are mostly dedicated to produce fast, near-real-time estimates. Preliminary results have been obtained using the maximum average cross-correlation method. They indicate that the tremor wavefronts are highly coherent among array stations and propagate across the seismic array with an apparent slowness of ~0.8 s/km and a back-azimuth of 135°N. These estimates have remained approximately constant since the onset of volcanic tremor, indicating a unique source and thus a single, continuing eruptive center.

Challenge for the accurate CMT estimation of the offshore earthquakes using ocean bottom pressure gauges as seismometers

NASA Astrophysics Data System (ADS)

Kubota, T.; Saito, T.; Suzuki, W.; Hino, R.

2017-12-01

When an earthquake occurs in offshore region, ocean bottom pressure gauges (OBP) observe the low-frequency (> 400s) pressure change due to tsunami and also high-frequency (< 200 s) pressure change due to seismic waves (e.g. Filloux 1983; Matsumoto et al. 2012). When the period of the seafloor motion is sufficiently long (> 20 s), the relation between seafloor dynamic pressure change p and seafloor vertical acceleration az is approximately given as p=ρ0h0az (ρ0: seawater density, h0: sea depth) (e.g., Bolshakova et al. 2011; Matsumoto et al.,2012; Saito and Tsushima, 2016, JGR; Saito, 2017, GJI). Based on this relation, it is expected that OBP can be used as vertical accelerometers. If we use OBP deployed in offshore region as seismometer, the station coverage is improved and then the accuracy of the earthquake location is also improved. In this study, we analyzed seismograms together with seafloor dynamic pressure change records to estimate the CMT of the interplate earthquakes occurred at off the coast of Tohoku on 9 March, 2011 (Mw 7.3 and 6.5) (Kubota et al., 2017, EPSL), and discussed the estimation accuracy of the centroid horizontal location. When the dynamic pressure change recorded by OBP is used in addition to the seismograms, the horizontal location of CMT was reliably constrained. The centroid was located in the center of the rupture area estimated by the tsunami inversion analysis (Kubota et al., 2017). These CMTs had reverse-fault mechanisms consistent with the interplate earthquakes and well reproduces the dynamic pressure signals in the OBP records. Meanwhile, when we used only the inland seismometers, the centroids were estimated to be outside the rupture area. This study proved that the dynamic pressure change in OBP records are available as seismic-wave records, which greatly helped to investigate the source process of offshore earthquakes far from the coast.

Challenge for the accurate CMT estimation of the offshore earthquakes using ocean bottom pressure gauges as seismometers

NASA Astrophysics Data System (ADS)

Kubota, T.; Saito, T.; Suzuki, W.; Hino, R.

2016-12-01

When an earthquake occurs in offshore region, ocean bottom pressure gauges (OBP) observe the low-frequency (> 400s) pressure change due to tsunami and also high-frequency (< 200 s) pressure change due to seismic waves (e.g. Filloux 1983; Matsumoto et al. 2012). When the period of the seafloor motion is sufficiently long (> 20 s), the relation between seafloor dynamic pressure change p and seafloor vertical acceleration az is approximately given as p=ρ0h0az (ρ0: seawater density, h0: sea depth) (e.g., Bolshakova et al. 2011; Matsumoto et al.,2012; Saito and Tsushima, 2016, JGR; Saito, 2017, GJI). Based on this relation, it is expected that OBP can be used as vertical accelerometers. If we use OBP deployed in offshore region as seismometer, the station coverage is improved and then the accuracy of the earthquake location is also improved. In this study, we analyzed seismograms together with seafloor dynamic pressure change records to estimate the CMT of the interplate earthquakes occurred at off the coast of Tohoku on 9 March, 2011 (Mw 7.3 and 6.5) (Kubota et al., 2017, EPSL), and discussed the estimation accuracy of the centroid horizontal location. When the dynamic pressure change recorded by OBP is used in addition to the seismograms, the horizontal location of CMT was reliably constrained. The centroid was located in the center of the rupture area estimated by the tsunami inversion analysis (Kubota et al., 2017). These CMTs had reverse-fault mechanisms consistent with the interplate earthquakes and well reproduces the dynamic pressure signals in the OBP records. Meanwhile, when we used only the inland seismometers, the centroids were estimated to be outside the rupture area. This study proved that the dynamic pressure change in OBP records are available as seismic-wave records, which greatly helped to investigate the source process of offshore earthquakes far from the coast.

Education and Public Outreach for the Cascadia Initiative--Engaging communities in their own Geologic Back Yards

NASA Astrophysics Data System (ADS)

Livelybrooks, D.; Toomey, D. R.; Brennan, D.; Mulder, G.

2013-12-01

The Cascadia Initiative is a four-year, amphibious project employing arrays of seismometers, pressure gauges, and GPS monitors. Its goals are to study the structure of the Juan de Fuca and Gorda plates, deformation of the leading edge of the North American plate, the nature of the locked zone between plates where large earthquakes occur, and inboard slow slip events. For the past three summers, members of the Cascadia Initiative Expedition Team (CIET), Oregon community college students and faculty, and other undergraduate and graduate students have participated in 3-6 cruises annually to deploy and recover ocean-bottom seismometers (OBSs) off the coast of California, Oregon, Washington and Vancouver Island. Additionally, Oregon K-12 educators have engaged in using low-cost and research-grade seismometers to characterize school site shaking hazards as a way to influence school leadership and address seismic hazards. As part of CIET's unique ';CC@Sea' program, community college students and instructors have developed videos, talks and posters based on their experiences, and present these to CC core science classes and other campus groups (e.g. ROV clubs) to help catalyze interest in geoscience and other STEM careers. These presentations include both scientific goals and experiential impressions, and serve to capture the teamwork and multiple skill sets found among ship and scientific crews at sea. As part of a Title IIb math-science partnership program, a team of middle- and high-school teachers is developing classroom projects around school seismic hazards, a very real possibility for we who live near the Cascadia subduction zone. Students will analyze data, report their findings, and provide recommendations focused on mitigating hazards to school administrators and school boards. This presentation will summarize how CIET's K-14 EPO efforts support student, teacher and the broader community engagement at the nexus of the geosciences and public policy. A K-12 teacher serves as a seismic signal source

Mantle Flow and Dehydration Beneath the Juan de Fuca Plate Revealed by Shear Velocity and Attenuation

NASA Astrophysics Data System (ADS)

Ruan, Y.; Forsyth, D. W.; Bell, S. W.

2017-12-01

At mid-ocean-ridge spreading centers, it is still unclear to what extent the upwelling is purely passive, driven by viscous drag of the separating plates, or dynamically driven by the buoyancy induced by melt retention and depletion of the mantle matrix. The distinct sensitivities of seismic wavespeed and attenuation to temperature, melt porosity, water content and major element composition yield some of the primary constraints on mid-ocean ridge processes and the associated flow pattern, melt distribution, and the interaction of spreading centers with hotspots. Extensive arrays of ocean-bottom seismometers (OBS) with better quality, longer deployment periods, and the application of noise-removal techniques together provided higher quality data in this study than in any previous regional study of velocity and attenuation of the upper mantle beneath a spreading center. Based on the fundamental-mode Rayleigh waves, we imaged shear wave attenuation and velocity models in the vicinity of the Juan de Fuca plate with the best resolution to date of any spreading center. There is strong attenuation centered at depths of 70-80 km, just below the expected dry solidus and somewhat deeper than predicted for a model of passive mantle upwelling beneath the spreading center. The shear velocity structure shows lowest velocities west of the spreading center, particularly near Axial Seamount and high velocities east of the axis extending to a greater depth than predicted by the passive flow model. Together, these observations support a model in which buoyant upwelling west of the spreading center first depletes and dehydrates the mantle above the dry solidus by melt removal and then the associated downwelling carries depleted, melt-free, residual mantle downward beneath the Juan de Fuca plate. This depleted, dehydrated, melt-free layer can explain why the average attenuation is lower than expected and the velocity is higher than expected in the 30 to 70 km depth range. The compositional buoyancy of the depleted mantle may in most places limit downwelling to the vicinity of the spinel peridotite to garnet peridotite transition at a depth of 80 km.

Shear wave velocity structure in the lithosphere and asthenosphere across the Southern California continent and Pacific plate margin using inversion of Rayleigh wave data from the ALBACORE project.

NASA Astrophysics Data System (ADS)

Price, A. C.; Weeraratne, D. S.; Kohler, M. D.; Rathnayaka, S.; Escobar, L., Sr.

2015-12-01

The North American and Pacific plate boundary is a unique example of past subduction of an oceanic spreading center which has involved oceanic plate capture and inception of a continental transform boundary that juxtaposes continental and oceanic lithosphere on a single plate. The amphibious ALBACORE seismic project (Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment) deployed 34 ocean bottom seismometers (OBS) on 15-35 Ma seafloor and offers a unique opportunity to compare the LAB in continental and oceanic lithosphere in one seismic study. Rayleigh waves were recorded simultaneously by our offshore array and 82 CISN network land stations from 2010-2011. Here we predict phase velocities for a starting shear wave velocity model for each of 5 regions in our study area and compare to observed phase velocities from our array in a least-squares sense that produces the best fit 1-D shear wave velocity structure for each region. Preliminary results for the deep ocean (seafloor 25-32 Ma) indicates high velocities reaching 4.5 km/s at depths of 50 km associated with the lithosphere for seafloor 25-32 Ma. A negative velocity gradient is observed below this which reaches a minimum of 4.0 km/s at 160 km depth. The mid-ocean region (age 13-25 Ma) indicates a slightly lower magnitude and shallower LVZ. The Inner Borderland displays the highest lithospheric velocities offshore reaching 4.8 km/s at 40 km depth indicating underplating. The base of the LVZ in the Borderland increases sharply from 4.0 km/s to 4.5 km/s at 80-150 km depth indicating partial melt and compositional changes. The LVZ displays a very gradual positive velocity gradient in all other regions such as the deep seafloor and continent reaching 4.5 km/s at 300 km depth. The deep ocean, Borderlands, and continental region each have unique lithospheric velocities, LAB depths, and LVZ character that indicate stark differences in mantle structure that occur on a single plate as well as across the continental margin.

Investigation of active faults in the Ionian Sea through seismological, geochemical and bathymetric data: the SEISMOFAULTS project

NASA Astrophysics Data System (ADS)

Sgroi, T.; Beranzoli, L.; Caruso, C.; Corbo, A.; Costanza, A.; De Caro, M.; D'Anna, G.; Doglioni, C.; Embriaco, D.; Frugoni, F.; Italiano, F.; Lazzaro, G.; Monna, S.; Montuori, C.; Nigrelli, A.; Passafiume, G.; Billi, A.; Cuffaro, M.; Albano, M.; Bosman, A.; Gasperini, L.; Ligi, M.; Martorelli, E.; Petracchini, L.; Polonia, A.; Scrocca, D.; Serracino, M.; Bigi, S.; Conti, A.; Proietti, G.; Ruggiero, L.; Tartarello, M. C.

2017-12-01

In a past and recent time, the Western Ionian Sea and surrounding regions of south Calabria and eastern Sicily (southern Italy) have been the site of destructive earthquakes (e.g. 1908, Mw 7.2; 1783, Mw 6.9; 1693, Mw 7.4; 1169, Mw 6.6; 362, Mw 6.6), which caused damage, devastation, and death (more than 80,000 deaths in 1908) and were followed by strong tsunamis. Although such events have been studied by many authors, their sources and generation mechanisms are still heavily debated both for earthquakes and tsunamis. The faults that generated such earthquakes are not yet known as it is unknown whether the associated tsunamis were generated directly by earthquakes or indirectly by seismically-triggered landslides. The lack of an adequate network of seismic stations at the bottom of the Ionian Sea and of a continuous acquisition of geophysical and geochemical parameters on the medium and long term prevents the full understanding of the tectonic, seismological, and geomorphologic phenomena of the Western Ionian Sea. A seismological and geochemical experiment, also accompanied by a detailed bathymetric survey, is now ongoing in the Ionian Sea from May 2017. Eight Ocean Bottom Seismometers and Hydrophones (OBS/H) and two modules for geochemical monitoring (CH4, CO2 and O) were deployed on the sea bottom (www.seismofaults.it). They will record seismological and geochemical signals for a period of about 12 months with the aim to: - determine whether faults are seismically active and can be sources of possible seismic hazard; - observe eventual premonitory elements, such degassing processes from structures such as mud volcanoes, characterizing the seismic movements along faults; - determine whether gravitational movements (e.g. landslides) along the Sicilian-Calabrian margins can be triggered by low magnitude earthquakes, and thus to better evaluate the tsunamigenic potential of the western Ionian region. The analyses of the new seismological and geochemical data, combined with data previously collected in the same area, will contribute to deepen the understanding of the tectonic and volcanic activities of the Ionian Sea, permitting to focus on the geodynamic picture of eastern Sicily offshore area.

Results from CAT/SCAN, the Calabria-Apennine-Tyrrhenian/Subduction-Accretion-Collision Network

NASA Astrophysics Data System (ADS)

Steckler, M. S.; Amato, A.; Guerra, I.; Armbruster, J.; Baccheschi, P.; Diluccio, F.; Gervasi, A.; Harabaglia, P.; Kim, W.; Lerner-Lam, A.; Margheriti, L.; Seeber, L.; Tolstoy, M.; Wilson, C. K.

2005-12-01

The Calabrian Arc region is the final remnant of a Western Mediterranean microplate driven by rollback. Calabria itself is an exotic block that rifted off Sardinia and opened the Tyrrhenian Sea back-arc basin in its wake. The Calabrian Arc rapidly advanced to the southeast, with subduction ahead and extension behind, following subduction rollback of the Mesozoic seafloor. The subduction zone meanwhile collided progressively with the Apulia to form the Apennines in peninsular Italy and with the Africa to form the Maghrebides in Sicily. The Calabrian Arc is where the transition from subduction to continental collision is occurring. The collisions on either side of Calabria have restricted oceanic subduction to a narrow 200-km salient with well-defined edges and seismicity that extends to over 500 km depth. The collisions have also slowed, or possibly even halted, the rapid advance of the arc. Whether rollback of the oceanic lower plate of the Ionian Sea continues and whether the upper plate of Calabria continues to move as an independent plate are both uncertain. The Calabrian-Apennine-Tyrrhenian/Subduction-Collision-Accretion Network (CAT/SCAN) is a passive experiment to study of the Calabrian Arc and the transition to the southern Apennines. The land deployment consisted of three phases. The initial phase included an array of 39 broadband seismometers onshore, deployed in the winter of 2003/4. In September 2004, the array was reduced to 28 broadband and 8 short-period instruments. In April 2005, the array was reduced once again to 20 broadband and 2 short-period instruments. The field deployment was completed in October 2005. Offshore, 12 broadband Ocean Bottom Seismometers (OBSs) were deployed in the beginning of October 2004. Data from 4 OBSs have been recovered so far with deployment durations from a few weeks to almost one year. Fishing activity has been strongly implicated in the early recoveries, (with one instrument returned by fishermen), and is suspected for the instruments that were not recovered. The experiment is determining the structure of the Calabrian subduction and southern Apennine collision systems and the structure of the transition from oceanic subduction in Calabria to continental collision in the southern Apennines. We have delineated a strong anisotropy with a fast direction following the curved arc, but weaker anisotropy beneath the Tyrrhenian Sea. Receiver function images show variations in crustal thickness throughout the region, consistent with previous conceptual models. We also image a negative polarity interface dipping to the southwest that we interpret as the main thrust ramp in the north transitioning to the subduction interface in the south. The transition from one to the other is marked by a loss of amplitude in the Moho conversion. Local seismicity is consistent with surface structure in showing extension normal and parallel to the Calabrian forearc as well as continuing southeastward motion of Calabria relative to the southern Apennines and Maghrebides.

The AlpArray Seismic Network: current status and next steps

NASA Astrophysics Data System (ADS)

Hetényi, György; Molinari, Irene; Clinton, John; Kissling, Edi

2016-04-01

The AlpArray initiative (http://www.alparray.ethz.ch) is a large-scale European collaboration to study the entire Alpine orogen at high resolution and in 3D with a large variety of geoscientific methods. The core element of the initiative is an extensive and dense broadband seismological network, the AlpArray Seismic Network (AASN), which complements the permanent seismological stations to ensure homogeneous coverage of the greater Alpine area. The some 260 temporary stations of the AlpArray Seismic Network are operated as a joint effort by a number of institutions from Austria, Bosnia-Herzegovina, Croatia, Czech Republic, France, Germany, Hungary, Italy, Slovakia and Switzerland. The first stations were installed in Spring 2015 and the full AASN is planned to be operational by early Summer 2016. In this poster we present the actual status of the deployment, the effort undertaken by the contributing groups, station performance, typical noise levels, best practices in installation as well as in data management, often encountered challenges, and planned next steps including the deployment of ocean bottom seismometers in the Ligurian Sea.

Search and Recovery Efforts for the ALSEP Data Tapes

NASA Technical Reports Server (NTRS)

Nagihara, S.; Nakamura, Y.; Lewis, L. R.; Williams, D. R.; Taylor, P. T.; Grayzeck, E. J.; Chi, P.; Schmidt, G. K.

2011-01-01

On NASA's first human lunar landing on Apollo II in July 1969, the astronauts deployed a set of scientific instruments called Early Apollo Science Experiments Package (EASEP). It was powered by a solar panel and operated for -20 earth-days and transmitted data to the Earth. This paved a way for deployment of more expansive instrument packages, powered by radioisotope thermoelectric generators, on Apollo 12, 14, 15, 16, and 17 in November 1969 through December 1972. They were called Apollo Lunar Surface Experiments Packages (ALSEPs). Each ALSEP consisted of a variety of instruments such as seismometers, magnetometers, solar wind spectrometers, heat flow probes, etc. The majority of these instruments kept functioning long after their one-year design lifetime requirement, and they transmitted data to the Earth until September 1977, when the program ended. Over the three decades that followed, users of the NSSDC-archived data have learned that many of the ALSEP instrument data are not complete. The present work is a progress report on the authors' recent effort for restoring the entire raw ALSEP data that were received from the Moon,

Cascadia, an ultracompact seismic instrument with over 200dB of dynamic range

NASA Astrophysics Data System (ADS)

Parker, Tim; Devanney, Peter; Bainbridge, Geoff; Townsend, Bruce

2017-04-01

Integration of geophysical instrumentation is clearly a way to lower overall station cost, make installations less complex, reduce installation time, increase station utility and value to a wider group of researchers, data miners and monitoring groups. Initiatives to expand early earthquake warning networks and observatories can use these savings for increasing station density. Integration of mature instrument systems such as broadband sensors and accelerometers used in strong motion studies has to be done with care to preserve the low noise and low frequency performance while providing over 200dB of dynamic range. Understanding the instrument complexities and deployment challenges allows the engineering teams to optimize the packaging to make installation and servicing cost effective, simple, routine and ultimately more reliable. We discuss early results from testing both in the lab and in the field of a newly released instrument called the Cascadia that integrates a broadband seismometer with a class A (USGS rating) accelerometer in a small stainless steel sonde suited for dense arrays in either ad hoc direct bury field deployments or in observatory quality shallow boreholes.

Shear Wave Velocity, Depth to Bedrock, and Fundamental Resonance Applied to Bedrock Mapping using MASW and H/V Analysis

NASA Astrophysics Data System (ADS)

Gonsiewski, J.

2015-12-01

Mapping bedrock depth is useful for earthquake hazard analysis, subsurface water transport, and other applications. Recently, collaborative experimentation provided an opportunity to explore a mapping method. Near surface glacial till shear wave velocity (Vs) where data is available from an array of 3-component seismometers were studied for this experiment. Vs is related to depth to bedrock (h) and fundamental resonance (Fo); Fo = Vs/(4h). The H/V spectral peak frequency of recordings from a 3-component seismometer yields a fundamental resonance estimate. Where a suitable average Vs is established, the depth to bedrock can be calculated at every seismometer. 3-component seismometer data was provided by Spectraseis. Geophones, seismographs, and an extra 3-component seismometer were provided by Wright State University for this study. For Vs analysis, three MASW surveys were conducted near the seismometer array. SurfSeis3© was used for processing MASW data. Overtones from complicated bedrock structure and great bedrock depth are improved by combining overtones from multiple source offsets from each survey. From MASW Vs and depth to bedrock results, theoretical fundamental resonance (Fo) was calculated and compared with the H/V peak spectral frequency measured by a seismometer at selected sites and processed by Geopsy processing software. Calculated bedrock depths from all geophysical data were compared with measured bedrock depths at nearby water wells and oil and gas wells provided by ODNR. Vs and depth to bedrock results from MASW produced similar calculated fundamental resonances to the H/V approximations by respective seismometers. Bedrock mapping was performed upon verifying the correlation between the theoretical fundamental resonance and H/V peak frequencies. Contour maps were generated using ArcGIS®. Contour lines interpolated from local wells were compared with the depths calculated from H/V analysis. Bedrock depths calculated from the seismometer array correlate with the major trends indicated by the surrounding wells. A final contour map was developed from depth to bedrock measured by all wells and depths calculated from the average Vs and estimated resonance at select Spectraseis 3-component seismometers.

Seismic Imaging of the Deep Crust in the Pull-Apart Basin off Maranhão-Barreirinhas-Ceará Margin, NW Brazil

NASA Astrophysics Data System (ADS)

Afilhado, Alexandra; Gallais, Flora; Moulin, Maryline; Schnürle, Philippe; Afonso Dias, Nuno; Soares, José; Loureiro, Afonso; Fuck, Reinhardt; Cupertino, José; Viana, Adriano; Matias, Luis; Evain, Mikael; Aslanian, Daniel

2017-04-01

Five profiles, with coincident multi-chanel and wide-angle seismic, were acquired during the MAGIC (Margins of brAsil, Ganha and Ivory Coast) cruise, in order to image the Maranhão-Barreirinhas-Ceará segment of the Brazilian Margins. The seismic experiment was conducted by Ifremer (Institut Français de Recherche pour l'Exploration de la Mer), UnB (University of Brasilia), FCUL (Faculdade de Ciencias da Universidade de Lisboa) and Petrobras. The main objective of the experiment is to understand the fundamental processes which lead to the thinning and breakup of the continental crust in a specific context of a pull-apart system, limited by two strike-slip borders. We present the main results evidenced by two of these profiles, MC3 and MC4, oriented in the directions of flow lines (E-W) and margin segmentation (SW-NE), respectively. The profile MC3 spans from the continental crust, near Sao Luis Craton, to the oceanic basin, north of Ceara. 31 Ocean Bottom Seismometers (OBS) from the Ifremer pool and 8 small arrays of 6 RefTek Land Seismic Stations (LSS) from the Brazilian pool were deployed in this profile, jointly with 400 km multi channel seismic acquisition. The profile MC4 spans from the Parnaiba and Barreirinhas Basins onshore to the oceanic basin, South of the Northern Brazilian Ridge. The MC4 seismic data includes 225 km multi channel seismic data and wide-angle data acquired in 19 OBS and 21 arrays of 3 LSS each, totaling a maximum source-receiver offset of 400 km. The analysis of these profiles evidence a NW-SE segmentation of the margin following the opening direction of this pull-apart basin, from unthinned continental crust (about 40 km thick) to thin oceanic crust. The width of the necking zone increases from about 50 km in the direction of flow-lines (MC3-Ilha da Santana margin), to more than 125 km in the direction of segmentation (MC4-Barreirinhas margin), at the corner of the pull-apart system, with two steps first in the upper crust then in middle/lower crust. The intermediate domain, is formed by a thick sedimentary basin overlying a substratum of 5 km- thickness, with velocity ranging from 6.2 to 6.6 km/s. Below, a 2-3 km thick layer with very high velocity (7.4-7.6 km/s) and marked by reflections at the top and base, is followed continuously towards the continent beneath the Parnaiba-Barreirinhas province, at the corner of the system. These observations favor a lower continental crust nature for this domain, in relation to its flow and exhumation in the flow-lines direction. Publication supported by FCT- project UID/GEO/50019/2013 - Instituto Dom Luiz

The Oceanic Crustal Structure of the Southwestern Subbasin in the South China Sea

NASA Astrophysics Data System (ADS)

Wu, Z.; Ruan, A.; Li, J.; Lee, C.

2012-12-01

Located at the southwestern part of the South China Sea (SCS) among the Zhongsha Islands(Macclesfield Bank), the east subbasin, the Nansha Islands(Dangerous Ground), the V type southwest subbasin (SWSB) is an unique ocean basin in all the three subbasins of SCS. The crustal structure is one of the key problems to study the formation and evolution of SWSB. During December 2010 to March 2011, Ocean Bottom Seismometers (OBSs) experiment has been carried out in the SWSB to get the deep crustal structure information, especially under the fossil spreading center. Three types of OBS, Sedis IV type, I-4C type and MicrOBS type have been used in the experiment, and the energy source was supplied by 6000 inch3 large volume air-gun. High quality seismic data of four 2D profiles which covered the fossil spreading center of SWSB have been acquired. The data of the experiment can supply evidence for the study of oceanic crustal structure of the SWSB and seafloor spreading course, etc. The profile 1 extended 130 km in length. A total of 8 OBSs were deployed at intervals of 10 or 15 km and 7 OBSs were recovered. The data of the 7 stations of profile 1 have been processed, which shows that the seismic records are clear and seismic phases are abundance, and the air-guns have enough energy supply. The velocity model was obtained by using an interactive trial-and-error 2D ray-tracing method. The crustal structure indicates that the crustal thickness under the SWSB is about 6 km, and the moho depth is about 10km. The results reveal that the crust of SWSB is normal oceanic crust with a thin sedimentary layer on the seamount and shallow moho surface. The crustal velocity under the spreading center is extremely low, which shows the characteristic of the deep crustal structure of the fossil spreading center. Acknowledgements This study was supported by the National Natural Science Foundation of China (Grant No. 91028006, 41106053, 41176046), Scientific Research Fund of the Second Institute of Oceanography, SOA(Grant No. JT1101) References: Ruan A G, Qiu X L, Li J B, et al. Wide aperture seismic sounding in the margin seas of China. South China Journal of Seismology,2009,29:10-18(in Chinese). Li J B, Jin X L, Gao J Y. Morpho-tectonic study on late-stage spreading of the Eastern Subbasin of South China Sea. Sci China Ser D-Earth Sci,2002, 45:978-989 WU Z L, LI J B, RUAN A G, et al. Crustal structure of the northwestern sub-basin, South China Sea: Results from a wide-angle seismic experiment[J]. Sci China Earth Sci, 2012,55:159-172. doi: 10.1007/s11430-011-4324-9.

Optimism Experiment and Development of Space-qualified Seismometers in France

NASA Technical Reports Server (NTRS)

Lognonne, P.; Karczewski, J. F.

1993-01-01

The OPTIMISM experiment will put two magnetometers and two seismometers on the Martian floor in 1995, within the framework of the Mars '94 mission. The seismometers are put within the two small surface stations. The seismometer sensitivity will be better than 10 exp -9 g at 1 Hz, 2 orders of magnitude higher than the Viking seismometer sensitivity. A priori waveform modeling for seismic signals on Mars shows that it will be sufficient to detect quakes with a seismic moment greater than 10 exp 15 Nm everywhere on Mars. Such events, according to the hypothesis of a thermoelastic cooling of the Martian lithosphere, are expected to occur at a rate close to one per week and may therefore be observed within the l-year lifetime of the experiment. Other aspects of the experiment are discussed.

Real-Time Environmental Artic Monitoring (R-TEAM).

DTIC Science & Technology

1987-11-01

critical points of the mooring. Tension, tilt, pressure and temperature data are recorded on solid state memory for the duration of the deployment. Two...To iUe Tna£ LA6aksIIorZ. Um DESCaiPTiow r oj.t.TAK 2ALUMINUM PIPE -ob.I’ -WALL. 5e1 . Sm IVI IlSdh7 Z BOT’TOM END CAPME G,15473 (5 2 R.OD 3__ MX 306 as...described in Reference 2. Each instrument, located at a critical point of the mooring, measures and records in solid state memory tension, tilt, temperature

Seismic Characterization Study of the Advanced Inertial Test Laboratory (AITL) Report

DTIC Science & Technology

2008-12-08

with different sensitivities and bandwidths, were used in this study. One was the model KS-2000 seismometer manufacture by Geotech . It was a single...the same for all the seismometers; some were as low as 40 Hz. The second model was a Geotech S-510. It is a single axis seismometer with an

Seismometers on Europa: Insights from Modeling and Antarctic Ice Shelf Analogs (Invited)

NASA Astrophysics Data System (ADS)

Schmerr, N. C.; Brunt, K. M.; Cammarano, F.; Hurford, T. A.; Lekic, V.; Panning, M. P.; Rhoden, A.; Sauber, J. M.

2013-12-01

The outer satellites of the Solar System are a diverse suite of objects that span a large spectrum of sizes, compositions, and evolutionary histories; constraining their internal structures is key for understanding their formation, evolution, and dynamics. In particular, Jupiter's icy satellite Europa has compelling evidence for the existence of a global subsurface ocean beneath a surface layer of water ice. This ocean decouples the ice shell from the solid silicate mantle, and amplifies tidally driven large-scale surface deformation. The complex fissures and cracks seen by orbital flybys suggest brittle failure is an ongoing and active process in the ice crust, therefore indicating a high level of associated seismic activity. Seismic probing of the ice, oceanic, and rocky layers would provide altogether new information on the structure, evolution, and even habitability of Europa. Any future missions (penetrators, landers, and rovers) planning to take advantage of seismometers to image the Europan interior would need to be built around predictions for the expected background noise levels, seismicity, wavefields, and elastic properties of the interior. A preliminary suite of seismic velocity profiles for Europa has been calculated using moment of inertia constraints, planetary mass and density, estimates of moon composition, thermal structure, and experimentally determined relationships of elastic properties for relevant materials at pressure, temperature and depth. While the uncertainties in these models are high, they allow us to calculate a first-order seismic response using 1-D and 3-D high frequency wave propagation codes for global and regional scale structures. Here, we show how future seismic instruments could provide detailed elastic information and reduced uncertainties on the internal structure of Europa. For example, receiver functions and surface wave orbits calculated for a single seismic instrument would provide information on crustal thickness and the depth of an ocean layer. Likewise, evaluation of arrival times of reflected wave multiples observed at a single seismic station would record properties of the mantle and core of Europa. Cluster analysis of waveforms from various seismic source mechanisms could be used to classify different types of seismicity originating from the ice and rocky parts of the moon. We examine examples of single station results for analogous seismic experiments on Earth, e.g., where broadband, 3-component seismometers have been placed upon the Ross Ice Shelf of Antarctica. Ultimately this work reveals that seismometer deployments will be essential for understanding the internal dynamics, habitability, and surface evolution of Europa, and that seismic instruments need to be a key component of future missions to surface of Europa and outer satellites.

Micromechanisms for optimism seismometer

NASA Technical Reports Server (NTRS)

Paulin, Nicolas; Dumas, Pierre; Pochard, Marc

1995-01-01

Within the framework of the Mars 94 mission, it was decided to design and build a new vertical axis seismometer in order to continuously record the seismic events occurring on the Mars planet. The mission requirements lead to very stringent constraints on power, volume, mass and shock resistance at the landing. The seismometer must be capable of automatic leveling and automatic fitting to the local gravity. This paper deals with the mechanisms designed for this seismometer. Due to the short allotted time for its development and low cost, the baseline was to apply the rules of spatial tribology and, when it was possible, to customize existing components for space applications.

Testing for Instrument Deployment by InSight Robotic Arm

NASA Image and Video Library

2015-03-04

In the weeks after NASA's InSight mission reaches Mars in September 2016, the lander's arm will lift two key science instruments off the deck and place them onto the ground. This image shows testing of InSight's robotic arm inside a clean room at NASA's Jet Propulsion Laboratory, Pasadena, California, about two years before it will perform these tasks on Mars. InSight -- an acronym for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport -- will launch in March 2016. It will study the interior of Mars to improve understanding of the processes that formed and shaped rocky planets, including Earth. One key instrument that the arm will deploy is the Seismic Experiment for Interior Structure, or SEIS. It is from France's national space agency (CNES), with components from Germany, Switzerland, the United Kingdom and the United States. In this scene, the arm has just deployed a test model of a protective covering for SEIS, the instrument's wind and thermal shield. The shield's purpose is to lessen disturbances that weather would cause to readings from the sensitive seismometer. Note: After thorough examination, NASA managers have decided to suspend the planned March 2016 launch of the Interior Exploration using Seismic Investigations Geodesy and Heat Transport (InSight) mission. The decision follows unsuccessful attempts to repair a leak in a section of the prime instrument in the science payload. http://photojournal.jpl.nasa.gov/catalog/PIA19144

The AlpArray Seismic Network: A Large-Scale European Experiment to Image the Alpine Orogen

NASA Astrophysics Data System (ADS)

Hetényi, György; Molinari, Irene; Clinton, John; Bokelmann, Götz; Bondár, István; Crawford, Wayne C.; Dessa, Jean-Xavier; Doubre, Cécile; Friederich, Wolfgang; Fuchs, Florian; Giardini, Domenico; Gráczer, Zoltán; Handy, Mark R.; Herak, Marijan; Jia, Yan; Kissling, Edi; Kopp, Heidrun; Korn, Michael; Margheriti, Lucia; Meier, Thomas; Mucciarelli, Marco; Paul, Anne; Pesaresi, Damiano; Piromallo, Claudia; Plenefisch, Thomas; Plomerová, Jaroslava; Ritter, Joachim; Rümpker, Georg; Šipka, Vesna; Spallarossa, Daniele; Thomas, Christine; Tilmann, Frederik; Wassermann, Joachim; Weber, Michael; Wéber, Zoltán; Wesztergom, Viktor; Živčić, Mladen

2018-04-01

The AlpArray programme is a multinational, European consortium to advance our understanding of orogenesis and its relationship to mantle dynamics, plate reorganizations, surface processes and seismic hazard in the Alps-Apennines-Carpathians-Dinarides orogenic system. The AlpArray Seismic Network has been deployed with contributions from 36 institutions from 11 countries to map physical properties of the lithosphere and asthenosphere in 3D and thus to obtain new, high-resolution geophysical images of structures from the surface down to the base of the mantle transition zone. With over 600 broadband stations operated for 2 years, this seismic experiment is one of the largest simultaneously operated seismological networks in the academic domain, employing hexagonal coverage with station spacing at less than 52 km. This dense and regularly spaced experiment is made possible by the coordinated coeval deployment of temporary stations from numerous national pools, including ocean-bottom seismometers, which were funded by different national agencies. They combine with permanent networks, which also required the cooperation of many different operators. Together these stations ultimately fill coverage gaps. Following a short overview of previous large-scale seismological experiments in the Alpine region, we here present the goals, construction, deployment, characteristics and data management of the AlpArray Seismic Network, which will provide data that is expected to be unprecedented in quality to image the complex Alpine mountains at depth.

McVCO handbook 1999

USGS Publications Warehouse

McChesney, P.J.

1999-01-01

McVCO is a microcontroller-based frequency generator that replaces the voltage controlled oscillator (VCO) used in the analog telemetry of seismic data. It accepts low-level signals from a seismometer and produces a frequency modulated subcarrier suitable for radio or telephone links to a data collection site. McVCO was designed for the purpose of improving the analog telemetry of signals within the Pacific Northwest Seismograph Network (PNSN). Its development received support from the University of Washington Geophysics Program, and both the Volcano Hazards and Earthquake Hazards programs of the United States Geological Survey (USGS). This handbook covers operation of McVCO, provides a technical reference for those who require a closer look at how McVCO works, and covers a collection of topics that need explicit treatment or that spring from deployment of the instrument.

A Low-Cost Energy-Efficient Cableless Geophone Unit for Passive Surface Wave Surveys.

PubMed

Dai, Kaoshan; Li, Xiaofeng; Lu, Chuan; You, Qingyu; Huang, Zhenhua; Wu, H Felix

2015-09-25

The passive surface wave survey is a practical, non-invasive seismic exploration method that has increasingly been used in geotechnical engineering. However, in situ deployment of traditional wired geophones is labor intensive for a dense sensor array. Alternatively, stand-alone seismometers can be used, but they are bulky, heavy, and expensive because they are usually designed for long-term monitoring. To better facilitate field applications of the passive surface wave survey, a low-cost energy-efficient geophone system was developed in this study. The hardware design is presented in this paper. To validate the system's functionality, both laboratory and field experiments were conducted. The unique feature of this newly-developed cableless geophone system allows for rapid field applications of the passive surface wave survey with dense array measurements.

Passive Seismic Monitoring for Rockfall at Yucca Mountain: Concept Tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, J; Twilley, K; Murvosh, H

2003-03-03

For the purpose of proof-testing a system intended to remotely monitor rockfall inside a potential radioactive waste repository at Yucca Mountain, a system of seismic sub-arrays will be deployed and tested on the surface of the mountain. The goal is to identify and locate rockfall events remotely using automated data collecting and processing techniques. We install seismometers on the ground surface, generate seismic energy to simulate rockfall in underground space beneath the array, and interpret the surface response to discriminate and locate the event. Data will be analyzed using matched-field processing, a generalized beam forming method for localizing discrete signals.more » Software is being developed to facilitate the processing. To date, a three-component sub-array has been installed and successfully tested.« less

Broadband FBG resonator seismometer: principle, key technique, self-noise, and seismic response analysis.

PubMed

Huang, Wenzhu; Zhang, Wentao; Luo, Yingbo; Li, Li; Liu, Wenyi; Li, Fang

2018-04-16

A broadband optical fiber seismometer based on FBG resonator is proposed for earthquake monitoring. The principle and key technique, high-resolution ultralow-frequency wavelength interrogation by dual-laser swept frequency and beat frequency method, are discussed and analyzed. From the simulation and test results, the seismometer works at broadband range from 0.01 Hz to 10 Hz with a sensitivity of better than 330 pm/g and the wavelength resolution of the interrogation system is better than 0.001 pm/√Hz from 0.1 Hz to 10 Hz. A three-channel correlation method is used to measure the self-noise of the seismometer. It reaches a noise level of 2.7 × 10 -7 ms -2 /√Hz@0.1 Hz, which is lower than the earth's background noise (the new high noise model, NHNM). An earthquake monitoring experiment is conducted in a low noise seismic station. The recorded seismic waves are analyzed, which suggests that the proposed seismometer has the ability to record the close microearthquake and distant great earthquake with a high signal-noise ratio (SNR). This is the first time that a FBG-based middle-long period seismometer with lower self-noise than NHNM and large dynamic range (100 dB) is reported.

Data Release Report for Source Physics Experiments 2 and 3 (SPE-2 and SPE-3) Nevada National Security Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Townsend, Margaret; Obi, Curtis

2015-01-26

The second Source Physics Experiment shot (SPE-2) was conducted in Nevada on October 25, 2011, at 1900:00.011623 Greenwich Mean Time (GMT). The explosive source was 997 kilograms (kg) trinitrotoluene (TNT) equivalent of sensitized heavy ammonium fuel oil (SHANFO) detonated at a depth of 45.7 meters (m). The third Source Physics Experiment shot (SPE-3) was conducted in Nevada on July 24, 2012, at 1800:00.44835 GMT. The explosive source was 905 kg TNT equivalent of SHANFO detonated at a depth of 45.8 m. Both shots were recorded by an extensive set of instrumentation that includes sensors both at near-field (less than 100more » m) and far-field (100 m or greater) distances. The near-field instruments consisted of three-component accelerometers deployed in boreholes at 15, 46, and 55 m depths around the shot and a set of single-component vertical accelerometers on the surface. The far-field network was composed of a variety of seismic and acoustic sensors, including short-period geophones, broadband seismometers, three-component accelerometers, and rotational seismometers at distances of 100 m to 25 kilometers. This report coincides with the release of these data for analysts and organizations that are not participants in this program. This report describes the second and third Source Physics Experiment shots and the various types of near-field and far-field data that are available.« less

Shallow velocity structure of Stromboli Volcano, Italy, derived from small-aperture array measurements of Strombolian tremor

USGS Publications Warehouse

Chouet, B.; De Luca, G.; Milana, G.; Dawson, P.; Martini, M.; Scarpa, R.

1998-01-01

The properties of the tremor wave field at Stromboli are analyzed using data from small-aperture arrays of short-period seismometers deployed on the north flank of the volcano. The seismometers are configued in two semi-circular arrays with radii of 60 and 150 m and a linear array with length of 600 m. The data are analyzed using a spatiotemporal correlation technique specifically designed for the study of the stationary stochastic wave field of Rayleigh and Love waves generated by volcanic activity and by scattering sources distributed within the island. The correlation coefficients derived as a function of frequency for the three components of motion clearly define the dispersion characteristics for both Rayleigh and Love waves. Love and Rayleigh waves contribute 70% and 30%, respectively, of the surface-wave power. The phase velocities of Rayleigh waves range from 1000 m/sec at 2 Hz to 350 m/sec at 9 Hz, and those for Love waves range from 700 to 400 m/sec over the same frequency band. These velocities are similar to those measured near Puu Oo on the east rift of Kilauea Volcano, Hawaii, although the dispersion characteristics of Rayleigh waves at Stromboli show a stronger dependence on frequency. Such low velocities are consistent with values expected for densely cracked solidified basalt. The dispersion curves are inverted for a velocity model beneath the arrays, assuming those dispersions represent the fundamental modes of Rayleigh and Love waves.

VoiLA: A multidisciplinary study of Volatile recycling in the Lesser Antilles Arc

NASA Astrophysics Data System (ADS)

Collier, J.; Blundy, J. D.; Goes, S. D. B.; Henstock, T.; Harmon, N.; Kendall, J. M.; Macpherson, C.; Rietbrock, A.; Rychert, C.; Van Hunen, J.; Wilkinson, J.; Wilson, M.

2017-12-01

Project VoiLA will address the role of volatiles in controlling geological processes at subduction zones. The study area was chosen as it subducts oceanic lithosphere formed at the slow-spreading Mid Atlantic Ridge. This should result in a different level and pattern of hydration to compare with subduction zones in the Pacific which consume oceanic lithosphere generated at faster spreading rates. In five project components, we will test (1) where volatiles are held within the incoming plate; (2) where they are transported and released below the arc; (3) how the volatile distribution and pathways relate to the construction of the arc; and (4) their relationship to seismic and volcanic hazards and the fractionation of economic metals. Finally, (5) the behaviour of the Lesser Antilles arc will be compared with that of other well-studied systems to improve our wider understanding of the role of water in subduction processes. To address these questions the project will combine seismology; petrology and numerical modelling of wedge dynamics and its consequences on dehydration and melting. So-far island-based fieldwork has included mantle xenolith collection and installation of a temporary seismometer network. In 2016 and 2017 we conducted cruises onboard the RRS James Cook that collected a network of passive-recording and active-recording ocean-bottom seismometer data within the back-arc, fore-arc and incoming plate region. A total of 175 deployments and recoveries were made with the loss of only 6 stations. The presentation will present preliminary results from the project.

Constraining the velocity structure of the Juan de Fuca plate from ridge to trench with a 2D tomographic study of wide angle OBS data

NASA Astrophysics Data System (ADS)

Boulahanis, B.; Canales, J. P.; Carbotte, S. M.; Carton, H. D.; Han, S.; Nedimovic, M. R.

2016-12-01

We conduct a two-dimensional travel time tomography study of a cross-plate, 300-km long, ocean bottom seismometer (OBS) transect collected as part of the Ridge to Trench (R2T) program to investigate the structure, evolution and state of hydration of the Juan de Fuca (JdF) plate from the ridge axis to subduction at the Cascadia margin offshore Washington. Our study employs the methodology of Korenaga et al. (2000) to derive a P-wave velocity model using wide-angle data from 15 OBSs spaced on average 15 km apart, spanning from the Endeavour segment of the JdF ridge to the Cascadia accretionary prism. A top down modeling approach is employed, first assessing velocities of the sediment layer, then the crust, and finally the upper mantle; at each stage of the inversion we fix the structure of the overlaying layers. Quality of data fit is evaluated using the root mean square value of the difference between predicted and observed travel times normalized by pick uncertainty. Previous studies provide a well-resolved multi-channel seismic (MCS) reflection image of this transect (Han et al., 2016), affording good constraints of the location of basement and Moho reflectors while allowing for comparison of the relationship between velocities and crustal structure. MCS results along this transect suggest evidence of little bending faulting confined to the sediment and upper-middle crust. An initial velocity model of the sediment layer above igneous crust is constructed utilizing the MCS derived sediment velocities. A one-dimensional velocity starting model of the oceanic crust is generated using the results of Horning et al. (in press) from a quasi-parallel cross-plate transect also acquired as part of the R2T study. Seismic velocities are compared to predicted velocities for crustal and mantle lithologies at temperatures estimated from a plate-cooling model and are used to provide constraints on water contents in these layers.

Crustal Deformation In the Northwestern Margin of the South China Sea: Results From Wide-angle Seismic Modeling

NASA Astrophysics Data System (ADS)

Huang, H.; Klingelhoefer, F.

2017-12-01

The South China Sea (SCS) has undergone episodic spreading during the Cenozoic Era. The long-term extension has shaped the continental margins of the SCS, leading to a progressive breakup of the lithosphere. Separated blocks and rift troughs, as controlled by tectonic stretching, contains key information about the deforming mechanism of the crust. In this work, we present a P-wave velocity model of a wide-angle seismic profile OBS2013-1 which passes through the NW margin of the SCS. Modeling of 25 ocean bottom seismometers (OBS) data revealed a detailed crustal structure and shallow complexities along the profile (Figure 1). The crust thins symmetrically across the Xisha Trough, from more than 20 km on flanks to 10 km in the central valley where the sediments thickens over 5 km; A volcano is situated on top of the centre basement high where the Moho drops slightly. At the distal margin around the Zhongsha Trough, the upper crust was detached and accordingly made the middle crust exhumed in a narrow area ( 20 km wide). Meanwhile, materials from the lower crust rises asymmetrically, increasing the crustal velocity by 0.3 km/s and may also giving rise to volcanisms along the hanging side. A 40 km wide hyper-stretched crust (with thickness of 5 km) was identified next to the Zhongsha Trough and covered by overflowing magma and post-rift sediments on the top. These observations argue for a depth-related and asymmetrically extension of the crust, including (1) detachment fault controls the deformation of the upper crust, leading to exhumation of the middle crust and asymmetrically rising of the lower crust, (2) The region adjacent to the exhumation region and with highly thinned crust can be considered as extinct OCT due to magma-starved supplying.

Breakup Style and Magmatic Underplating West of the Lofoten Islands, Norway, Based on OBS Data.

NASA Astrophysics Data System (ADS)

Breivik, A. J.; Faleide, J. I.; Mjelde, R.; Murai, Y.; Flueh, E. R.

2014-12-01

The breakup of the Northeast Atlantic in the Early Eocene was magma-rich, forming the major part of the North Atlantic Igneous Province (NAIP). This is seen as extrusive and intrusive magmatism in the continental domain, and as a thicker than normal oceanic crust produced the first few million years after continental breakup. The maximum magma productivity and the duration of excess magmatism varies along the margins of Northwest Europe and East Greenland, to some extent as a function of the distance from the Iceland hotspot. The Vøring Plateau off mid-Norway is the northernmost of the margin segments in northwestern Europe with extensive magmatism. North of the plateau, magmatism dies off towards the Lofoten Margin, marking the northern boundary of the NAIP here. In 2003, as part of the Euromargins Program we collected an Ocean Bottom Seismometer (OBS) profile from mainland Norway, across the Lofoten Islands, and out into the deep ocean. Forward velocity modeling using raytracing reveals a continental margin that shows transitional features between magma-rich and magma-poor rifting. On one hand, we detect an up to 2 km thick and 40-50 km wide magmatic underplate of the outer continent, on the other hand, continental thinning is greater and intrusive magmatism less than farther south. Continental breakup also appears to be somewhat delayed compared to breakup on the Vøring Plateau, consistent with increased extension. This indicates that magmatic diking, believed to quickly lead to continental breakup of volcanic margins and thus to reduce continental thinning, played a much lesser role here than at the plateau. Early post-breakup oceanic crust is up to 8 km thick, less than half of that observed farther south. The most likely interpretation of these observations, is that the source for the excess magmatism of the NAIP was not present at the Lofoten Margin during rifting, and that the excess magmatism actually observed was the result of lateral transport from the south around breakup time.

Effects of thermal variability on broadband seismometers: Controlled experiments, observations, and implications

USGS Publications Warehouse

Doody, Claire; Ringler, Adam; Anthony, Robert E.; Wilson, David; Holland, Austin; Hutt, Charles R.; Sandoval, Leo

2017-01-01

Isolating seismic instruments from temperature fluctuations is routine practice within the seismological community. However, the necessary degree of thermal stability required in broadband installations to avoid generating noise or compromising the fidelity in the seismic records is largely unknown and likely application dependent. To quantify the temperature sensitivity of seismometers over a broad range of frequencies, we artificially induced local temperature changes on three different models of seismometers to measure the effect of thermal variations on seismometer output. We found that diurnal temperature changes above 0.002°C root mean square (rms) showed significant changes in velocity and acceleration output in comparison to thermally stable reference measurements. We also found that sensor incoherent self‐noise increased with temperature variation; these increases in noise can be modeled as 1/f">1/f noise (pink noise), and are unlikely to be easily corrected for. These experimental results are compared with the data from Incorporated Research Institutions for Seismology (IRIS) U.S. Geological Survey (USGS) Global Seismographic Network (GSN) station TUC (Tucson, Arizona). This station is well instrumented with temperature sensors and has three different broadband seismometers, each of which uses a different method of thermal isolation. We show that the water bricks and borehole installations give ample temperature attenuation to thermally isolate seismometers from diurnal thermal variability that would compromise seismic data. We find that seismometer installations that provide thermal stability below 0.002°C rms could help to improve long‐period vertical seismic data across the GSN by decreasing temperature‐driven 1/f">1/f noise.

Broadband Array Analysis of the 2005 Episodic Tremor and Slip Event in Northern Cascadia

NASA Astrophysics Data System (ADS)

Wech, A.; Creager, K.; McCausland, W.; Frassetto, A.; Qamar, A.; Derosier, S.; Carmichael, J.; Malone, S.; Johnson, D.

2005-12-01

The region of Cascadia from the Olympic Mountains through southern Vancouver Island and down-dip of the subduction megathrust has repeatedly experienced episodes of slow slip. This episodic slip, which has been observed to take place over a period of two to several weeks, is accompanied by a seismic tremor signal. Based on the average recurrence interval of 14 months, the next episodic tremor and slip (ETS) event should occur within six weeks of mid-September, 2005. Indeed, it appears to have begun on September 3, as this abstract was being written. In order to record this anticipated event, we deployed an array of 11 three-component seismometers on the northern side of the Olympic Peninsula augmenting Pacific Northwest Seismographic Network stations as well as the first few EarthScope BigFoot stations and Plate Boundary Observatory borehole seismometers. This seismic array was comprised of six short-period and five broadband instruments with spacings of 500 m and 2200 m respectively. In conjunction with this Earthscope seismic deployment, we also installed a dense network of 29 temporary, continuous GPS stations across the entire Olympic Peninsula to integrate seismic and geodetic observations. One of the primary goals of this research is to utilize the broadband instrumentation in the array to investigate the possible correlation of low frequency energy with the rest of the tremor activity. ETS has been carefully investigated at high-frequency (seismic tremor at 2-6 Hz) and very low-frequency (slip occurring over weeks, observed by GPS). An important goal of this experiment is to investigate the possibility that the tremor generates intermediate, low-frequency signals. Preliminary analysis of short-period array recordings of the July, 2004 ETS event suggests that the tremor displays signs of lower-frequency energy (~0.5 Hz) correlated with its higher frequency activity. Our array should enable us to distinguish low- frequency signals originating in the direction of high-frequency tremor from noise in other directions. We will present an analysis of the low-frequency energy associated with this slip event.

Martian Ambient Seismic Noise: from the first modeling to the future data of the InSight Seismic experiment.

NASA Astrophysics Data System (ADS)

Lognonne, P. H.; Banerdt, W. B.; Mimoun, D.; Kobayashi, N.; Panning, M. P.; Pike, W. T.; Giardini, D.; Christensen, U. R.; Nishikawa, Y.; Murdoch, N.; Kawamura, T.; Kedar, S.; Spiga, A.

2014-12-01

The InSight NASA Discovery mission is expected to deploy a 3 axis VBB and a 3 axis SP seismometer on Mars by late september 2016. This seismic station will explore the Martian ambient noise, in addition to more classical science goals related to the detection of Marsquakes, Meteoritic Impacts and Tides. Mars, in contrast with the Earth (with both atmosphere and ocean) and the Moon (with no atmosphere nor ocean) is expected to have ambient noise only related to its atmosphere. Mars seismic data are therefore expecting to reveal the atmospheric coupling for a different atmospheric dynamics than Earth, especially in the 0.1-1 Hz bandwidth, dominated by oceanic microseisms on Earth. We rapidly present the expected performances of the SEIS experiment onboard InSight. This experiment is based on two 3 axis seismometers, one covering the tide and low seismic frequencies (up to 10 Hz) and a second one covering the high frequencies (from 0.1 Hz to 50 Hz). Both sensors are mounted on a sensors plateform, deployed by a robotic arm 1-2 meters from the lander and covered by thermal protection and a wind protection. The expected performances indicates that signal as low as 10**(-9) m/s**2/Hz**(1/2) will be detected in the 0.005-2 Hz bandwidth. We then focus on the modeling of this ambient atmospheric noise.This modeling has been done not only from constraints gathered by the atmospheric sensors of previous Mars missions (e.g. Viking and Pathfinder) but also by numerical modeling of the atmospheric perturbations, both at global scale and mesoscale. Theoretical estimation of the ambient noise has then been obtained for the pressure-correlated surface loading and the stochastic excitation of surface waves, at both long and very long period (e.g. Mars hum) and at medium or short period (e.g. regional and local generated surface waves). Results shows that most of these source of ambient noise will be detected, likely during the day for those generated locally and possibly during the night for those of global origin.

Exploring Seismic Noise with the USArray Transportable Array

NASA Astrophysics Data System (ADS)

Woodward, R.; Busby, R. W.; Simpson, D. W.

2009-12-01

The large number of seismic stations that comprise the EarthScope USArray Transportable Array (TA) seismic network provide an unparalleled opportunity for studying how seismic noise evolves with time over a large portion of the North American continent. Power spectra for every station in the TA data are computed automatically, for every hour of every station-day, by the Quality Analysis Control Kit (QUACK) system at the IRIS Data Management Center. The power spectra utilize hour-long data segments, with 50% overlap between segments, providing spectral values in the band between 20 Hz and 172 s. Thus, at any in-band frequency one can construct a continuous two-year time history of seismic noise for every TA station. When the time variation of the power spectra values across the array are rendered as individual movie frames one can examine the evolution of seismic noise across the full spatio-temporal extent of the TA. Overall, the background noise levels (especially at periods below 10 s) are remarkably uniform across the entire array. Numerous expected features are present, including diurnal and annual variations, enhanced noise levels at coastal stations, transients related to large storms, and episodes when the observations of background noise are dominated by earthquake energy. Upgrades to the TA station instrumentation will provide the capability to measure additional physical factors relevant to seismic noise. All TA stations deployed after August 2009 include MEMS barometers that can measure atmospheric pressure from DC to approximately 0.1 Hz. In additional, several stations have been temporarily equipped with infrasound sensors. Previous research has highlighted the direct effect of atmospheric pressure fluctuations on very long period vertical seismometers. The relationship to noise observed on horizontal seismometers is more complex. However, with a large number of uniform installations it may be possible to make further progress. We will present analyses of the spatio-temporal evolution of noise observed on the TA stations and present preliminary results from the barometers and infrasound sensors that have been deployed with TA stations so far. We will discuss opportunities for augmenting TA stations with additional sensors that may further elucidate seismic noise processes.

Is the Isabella anomaly a fossil slab or the foundered lithospheric root of the Sierra Nevada batholith?

NASA Astrophysics Data System (ADS)

Hoots, C. R.; Schmandt, B.; Clayton, R. W.; Hansen, S. M.; Dougherty, S. L.

2015-12-01

The Isabella Anomaly is a volume of relatively high seismic velocity upper mantle beneath the southern Great Valley in California. We deployed ~45 broadband seismometers in central California to test two main hypotheses for the origin of the Isabella Anomaly. One suggests that the Isabella Anomaly is the foundered lithospheric root of the southern Sierra Nevada batholith, which delaminated on account of eclogite-rich composition and translated westward as it began to sink into the asthenosphere. The other hypothesis suggests that the Isabella Anomaly is a fossil slab fragment attached to the Monterey microplate that lies offshore of central California and thus it is mechanically coupled to the Pacific plate. Prior seismic imaging with ~70 km station spacing cannot resolve the landward termination of Monterey microplate lithosphere beneath coastal California or where/if the Isabella Anomaly is attached to North America lithosphere beneath the Great Valley. The new temporary broadband array consists of 40 broadband seismometers with ~7 km spacing extending from the central California coast to the western Sierra Nevada batholith, plus some outliers to fill gaps in the regional network coverage. The temporary array was initially deployed in early 2014 and will continue to record until October 2015 so the complete data are not yet available. Preliminary Ps scattered wave images show an abrupt ~6 km increase in Moho depth eastward across the San Andreas fault, a strong positive impedance contrast that dips westward from ~7-25 km beneath Great Valley, and a sharp Moho with a slight westward dip beneath the western edge of the Sierra Nevada batholith. Apparently low impedance contrast characterizes the Moho beneath the eastern Great Valley and foothills, consistent with near mantle velocities in the lower crust. Processing of the cumulative data that will be available in October 2015 and incorporation of new tomography models into scattered wave imaging are needed before assessing the significance of potential uppermost mantle interfaces that may represent edges of the Isabella Anomaly. Results from Ps and Sp scattered wave imaging, ambient noise surface wave tomography, teleseismic body-wave tomography, and teleseismic shear wave splitting will be presented.

Benchmarking passive seismic methods of estimating the depth of velocity interfaces down to ~300 m

NASA Astrophysics Data System (ADS)

Czarnota, Karol; Gorbatov, Alexei

2016-04-01

In shallow passive seismology it is generally accepted that the spatial autocorrelation (SPAC) method is more robust than the horizontal-over-vertical spectral ratio (HVSR) method at resolving the depth to surface-wave velocity (Vs) interfaces. Here we present results of a field test of these two methods over ten drill sites in western Victoria, Australia. The target interface is the base of Cenozoic unconsolidated to semi-consolidated clastic and/or carbonate sediments of the Murray Basin, which overlie Paleozoic crystalline rocks. Depths of this interface intersected in drill holes are between ~27 m and ~300 m. Seismometers were deployed in a three-arm spiral array, with a radius of 250 m, consisting of 13 Trillium Compact 120 s broadband instruments. Data were acquired at each site for 7-21 hours. The Vs architecture beneath each site was determined through nonlinear inversion of HVSR and SPAC data using the neighbourhood algorithm, implemented in the geopsy modelling package (Wathelet, 2005, GRL v35). The HVSR technique yielded depth estimates of the target interface (Vs > 1000 m/s) generally within ±20% error. Successful estimates were even obtained at a site with an inverted velocity profile, where Quaternary basalts overlie Neogene sediments which in turn overlie the target basement. Half of the SPAC estimates showed significantly higher errors than were obtained using HVSR. Joint inversion provided the most reliable estimates but was unstable at three sites. We attribute the surprising success of HVSR over SPAC to a low content of transient signals within the seismic record caused by low levels of anthropogenic noise at the benchmark sites. At a few sites SPAC waveform curves showed clear overtones suggesting that more reliable SPAC estimates may be obtained utilizing a multi-modal inversion. Nevertheless, our study indicates that reliable basin thickness estimates in the Australian conditions tested can be obtained utilizing HVSR data from a single seismometer, without a priori knowledge of the surface-wave velocity of the basin material, thereby negating the need to deploy cumbersome arrays.

Multidirectional seismo-acoustic wavefield of strombolian explosions at Yasur, Vanuatu using a broadband seismo-acoustic network, infrasound arrays, and infrasonic sensors on tethered balloons

NASA Astrophysics Data System (ADS)

Matoza, R. S.; Jolly, A. D.; Fee, D.; Johnson, R.; Kilgour, G.; Christenson, B. W.; Garaebiti, E.; Iezzi, A. M.; Austin, A.; Kennedy, B.; Fitzgerald, R.; Key, N.

2016-12-01

Seismo-acoustic wavefields at volcanoes contain rich information on shallow magma transport and subaerial eruption processes. Acoustic wavefields from eruptions are predicted to be directional, but sampling this wavefield directivity is challenging because infrasound sensors are usually deployed on the ground surface. We attempt to overcome this observational limitation using a novel deployment of infrasound sensors on tethered balloons in tandem with a suite of dense ground-based seismo-acoustic, geochemical, and eruption imaging instrumentation. We present preliminary results from a field experiment at Yasur Volcano, Vanuatu from July 26th to August 4th 2016. Our observations include data from a temporary network of 11 broadband seismometers, 6 single infrasonic microphones, 7 small-aperture 3-element infrasound arrays, 2 infrasound sensor packages on tethered balloons, an FTIR, a FLIR, 2 scanning Flyspecs, and various visual imaging data. An introduction to the dataset and preliminary analysis of the 3D seismo-acoustic wavefield and source process will be presented. This unprecedented dataset should provide a unique window into processes operating in the shallow magma plumbing system and their relation to subaerial eruption dynamics.

GENERAL EARTHQUAKE-OBSERVATION SYSTEM (GEOS).

USGS Publications Warehouse

Borcherdt, R.D.; Fletcher, Joe B.; Jensen, E.G.; Maxwell, G.L.; VanSchaack, J.R.; Warrick, R.E.; Cranswick, E.; Johnston, M.J.S.; McClearn, R.

1985-01-01

Microprocessor technology has permitted the development of a General Earthquake-Observation System (GEOS) useful for most seismic applications. Central-processing-unit control via robust software of system functions that are isolated on hardware modules permits field adaptability of the system to a wide variety of active and passive seismic experiments and straightforward modification for incorporation of improvements in technology. Various laboratory tests and numerous deployments of a set of the systems in the field have confirmed design goals, including: wide linear dynamic range (16 bit/96 dB); broad bandwidth (36 hr to 600 Hz; greater than 36 hr available); selectable sensor-type (accelerometer, seismometer, dilatometer); selectable channels (1 to 6); selectable record mode (continuous, preset, trigger); large data capacity (1. 4 to 60 Mbytes); selectable time standard (WWVB, master, manual); automatic self-calibration; simple field operation; full capability to adapt system in the field to a wide variety of experiments; low power; portability; and modest costs. System design goals for a microcomputer-controlled system with modular software and hardware components as implemented on the GEOS are presented. The systems have been deployed for 15 experiments, including: studies of near-source strong motion; high-frequency microearthquakes; crustal structure; down-hole wave propagation; teleseismicity; and earth-tidal strains.

Assessing Multiple Methods for Determining Active Source Travel Times in a Dense Array

NASA Astrophysics Data System (ADS)

Parker, L.; Zeng, X.; Thurber, C. H.; Team, P.

2016-12-01

238 three-component nodal seismometers were deployed at the Brady Hot Springs geothermal field in Nevada to characterize changes in the subsurface as a result of changes in pumping conditions. The array consisted of a 500 meter by 1600 meter irregular grid with 50 meter spacing centered in an approximately rectangular 1200 meter by 1600 meter grid with 200 meter spacing. A large vibroseis truck (T-Rex) was deployed as an active seismic source at 216 locations. Over the course of 15 days, the truck occupied each location up to four times. At each location a swept-frequency source between 5 and 80 Hz over 20 seconds was produced using three vibration modes: longitudinal S-wave, transverse S-wave, and P-wave. Seismic wave arrivals were identified using three methods: cross-correlation, deconvolution, and Wigner-Ville distribution (WVD) plus the Hough Transform (HT). Surface wave arrivals were clear for all three modes of vibration using all three methods. Preliminary tomographic models will be presented, using the arrivals of the identified phases. This analysis is part of the PoroTomo project: Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology; http://geoscience.wisc.edu/feigl/porotomo.

High-resolution Body Wave Tomography of the Ross Sea Embayment, Antarctica

NASA Astrophysics Data System (ADS)

Nyblade, A.; White-Gaynor, A.; Wiens, D.; Aster, R. C.; Gerstoft, P.; Bromirski, P. D.; Stephen, R. A.; Winberry, J. P.; Huerta, A. D.; Anandakrishnan, S.; Wilson, T. J.

2016-12-01

The West Antarctic Rift System (WARS) remains the least understood continental rift system on the planet. The WARS is largely composed of the Ross Sea Embayment, which is overlain by the Ross Ice Shelf between Marie Byrd Land and the Transantarctic Mountains. Active volcanism on Ross Island continues to challenge our understanding of the seismically quiescent rift system. Previous regional-scale body wave tomographic investigations have identified areas of low seismic wave speed to about 200 km depth beneath Ross Island. However mantle structure under the Ross Sea Embayment away from Ross Island has not been previously well imaged. For this investigation we utilize teleseismic P waves recorded on the recently deployed RIS/DRIS network, which consists of 34 seismometers deployed across the Ross Ice Shelf, along with data from nearby POLENET stations and TAMSEIS stations. Relative P wave travel time residuals were obtained from 560 events using a multichannel cross correlation method, and have been inverted to obtain a preliminary model of the upper mantle. Initial results suggest that the low wave speed structure under Ross Island does not extend beneath the Ross Sea Embayment portion of the WARS.

Wireless Seismometer for Venus

NASA Technical Reports Server (NTRS)

Ponchak, George E.; Scardelletti, Maximilian C.; Taylor, Brandt; Beard, Steve; Clougherty, Brian; Meredith, Roger D.; Beheim, Glenn M.; Kiefer, Walter S.; Hunter, Gary W.

2014-01-01

Measuring the seismic activity of Venus is critical to understanding its composition and interior dynamics. Because Venus has an average surface temperature of 462 C and the challenge of providing cooling to multiple seismometers, a high temperature, wireless sensor using a wide bandgap semiconductor is an attractive option. This paper presents progress towards a seismometer sensor with wireless capabilities for Venus applications. A variation in inductance of a coil caused by a 1 cm movement of a ferrite probe held in the coil and attached to a balanced leaf-spring seismometer causes a variation of 80 MHz in the transmitted signal from the oscillator sensor system at 420 C, which correlates to a 10 kHz mm sensitivity when the ferrite probe is located at the optimum location in the coil.

Melt distribution along the axis of ultraslow spreading mid-ocean ridges

NASA Astrophysics Data System (ADS)

Schlindwein, V. S. N.; Schmid, F.; Meier, M.

2017-12-01

Ultraslow spreading mid-ocean ridges (<15 mm/y full spreading rate) differ from faster spreading ridges by their uneven melt distribution. Crustal thickness varies along axis from zero to more than 8 km at volcanic centers. These volcanic centers receive more melt than the regional average and may be sustained for millions of years. The segmentation pattern and active volcanism at ultraslow spreading ridges greatly differs from faster spreading ridges. Using networks of ocean bottom seismometers at three differing ridge segments, we could show that the maximum depth of brittle faulting, equivalent approximately to temperatures of 600-700°C, varies drastically along axis. Ridge sections that lack an igneous crust exhibit a thick lithosphere as evidenced by the deepest mid-ocean ridge earthquakes observed so far at more than 30 km depth. Beneath areas of basalt exposure, in particular beneath pronounced volcanic centers, the axial lithosphere may be more than 15 km thinner allowing for melt flow at the base of the lithosphere towards the volcanoes, a process that has been postulated to explain the uneven along-axis melt distribution. Spreading events at ultraslow spreading ridges are unusual as we found from two spreading episodes at 85°E Gakkel Ridge and Segment 8 volcano on the Southwest Indian Ridge. These eruptions were preceded or accompanied by large (M>5) and long-lasting earthquake swarms and active magmatism lasted over 3-16 years. A massive hydrothermal event plume and sounds from deep submarine explosive volcanism were observed at Gakkel Ridge. At the Segment 8 volcano, we imaged a melt reservoir extending to about 8 km depth below the volcano that potentially fed a sill intrusion recorded by an ocean bottom seismometers about 30 km away at a neighboring subordinate volcanic center. To better understand the segmentation and melt transport at ultraslow spreading rigdes, we recently conducted a segment-scale seismicity survey of Knipovich Ridge in the Norwegian-Greenland Sea. Here we deployed 28 ocean bottom seismometers along 160 km of ridge axis for one year, the currently largest mid-ocean ridge microseismicity experiment.

Redesign of the Electronics and the Mechanical Sensor of the STS-1 Very Broadband Seismometer

NASA Astrophysics Data System (ADS)

Romanowicz, B.; van Zandt, T.; Friday, J.; Karavas, W.; Porritt, R.; Uhrhammer, R.; Wielandt, E.

2008-12-01

The STS-1 VBB, widely viewed as the finest VBB sensor in the world, is currently the principal broad-band seismometer used by the Global Seismographic Network (GSN), GEOSCOPE, and several other global or regional seismic networks. Its continued operation is critical to future, fundamental research in a number of important disciplines within seismology. These include modal studies of the earth, the determination of source processes of very large earthquakes, and tsunami warning. We have recently completed the development of a replacement electronics module for the Streckeisen STS-1 Very Broad-Band (VBB) seismometer. This module maintains the outstanding analog performance of the original sensor electronics, while providing a number of unique performance enhancements that will improve the operability of STS-1 sensors within a modern, digital seismic network. We describe the attributes of this new electronics module, which has now reached production stage. As a second step in this collaboration between the Berkeley Seismological Laboratory and Metrozet (Inc), we have started the development of a commercially-viable replacement to the aging, but state-of-the-art mechanical sensor. We discuss the goals of this new project. The design of the new sensor aims at maintaining many of the unique features that have made the original sensor the world's finest instrument for low frequency seismic recording. It will, however, implement a number of enhancements that promise to improve operating performance and ease-of-use. These include the use of capacitive position sensing to reduce high frequency self-noise, an increase in the upper corner frequency of the sensor, much tighter tolerance (sensor-to-sensor) in scalar response values, and a new, highly-integrated package for deploying the sensors as a standard triaxial set. Importantly, the replacement sensor development is driven by principles of "design-for manufacturing". As such, the new sensor will include a number of features that will allow a modern, "deterministic manufacturing process" to replace what was historically an iterative, "workshop" approach to manufacture the STS-1. This is crucial to reducing the cost, and manufacturing lead time, of the new sensor.

Microseismic Events Detection on Xishancun Landslide, Sichuan Province, China

NASA Astrophysics Data System (ADS)

Sheng, M.; Chu, R.; Wei, Z.

2016-12-01

On landslide, the slope movement and the fracturing of the rock mass often lead to microearthquakes, which are recorded as weak signals on seismographs. The distribution characteristics of temporal and spatial regional unstability as well as the impact of external factors on the unstable regions can be understand and analyzed by monitoring those microseismic events. Microseismic method can provide some information inside the landslide, which can be used as supplementary of geodetic methods for monitoring the movement of landslide surface. Compared to drilling on landslide, microseismic method is more economical and safe. Xishancun Landslide is located about 60km northwest of Wenchuan earthquake centroid, it keep deforming after the earthquake, which greatly increases the probability of disasters. In the autumn of 2015, 30 seismometers were deployed on the landslide for 3 months with intervals of 200 500 meters. First, we used regional earthquakes for time correction of seismometers to eliminate the influence of inaccuracy GPS clocks and the subsurface structure of stations. Due to low velocity of the loose medium, the travel time difference of microseismic events on the landslide up to 5s. According to travel time and waveform characteristics, we found many microseismic events and converted them into envelopes as templates, then we used a sliding-window cross-correlation technique based on waveform envelope to detect the other microseismic events. Consequently, 100 microseismic events were detected with the waveforms recorded on all seismometers. Based on the location, we found most of them located on the front of the landslide while the others located on the back end. The bottom and top of the landslide accumulated considerable energy and deformed largely, radiated waves could be recorded by all stations. What's more, the bottom with more events seemed very active. In addition, there were many smaller events happened in middle part of the landslide where released less energy, generated signals could be recorded only by a few stations. Based on the distribution of those microseismic events, we found four unstable regions which agreed well with deformed areas monitored by Geodesy methods. The distribution of those microseismic events, should be related to internal structure and movement of the landslide.

SIIOS in Alaska - Testing an `In-Vault' Option for a Europa Lander Seismometer.

NASA Astrophysics Data System (ADS)

Bray, V. J.; Weber, R. C.; DellaGiustina, D. N.; Bailey, H.; Schmerr, N. C.; Pettit, E. C.; Dahl, P.; Albert, D.; Avenson, B.; Byrne, S.; Siegler, M.; Bland, M. T.; Patterson, G. W.; Selznick, S.

2017-12-01

The surface environment of Europa within the radiation-heavy jovian system, poses extreme technical challenges for potential landed missions. The need for radiation shielding and protection from the cold requires instruments to be housed within a thermally insulated and radiation protected `vault'. Unfortunately, this is non-ideal for seismometers as instrument-to-surface coupling is an important factor in the quality of returned data. Delivering a seismic package to an icy world would therefore benefit from the development of a cold-tolerant, radiation-hardened sensor that can survive outside of a protective vault. If such an instrument package were not technologically mature enough, or if lander safety considerations prevent deployment on lander legs, an in-vault location is still a viable option. For such a case, a better understanding of the transmission of seismic signals received through the lander legs is necessary for interpretation of the received signals. The performance, mass, and volume of the `Seismometer to investigate ice and ocean structure' (SIIOS) already meet or exceed flight requirements identified in lander studies for the icy moon Europa. We are testing this flight-candidate in several configurations around and within a lander mock-up, assuming a 1x1 meter vault with extended legs. We compare the received signals from a SIIOS device on the ice with those received by an identical sensor directly above it in the `vault'. We also compare the data from these single-point receivers to that received by two short base-line arrays - A 4-point "in-vault" array and another 4-point array arranged at the ice surface at the base of the lander legs. Our field-testing is performed at Gulkana Glacier, Alaska. The summer melt season provides kilometer-scale regions of coexisting ice, water, and silicate material, thereby providing seismic contrasts analogous to the ice-water layers and possible sub-surface lakes expected at Europa. We demonstrate the sensitivity of SIIOS to detect a variety of passive and active sources from both on-ice and lander-mounted locations, and compare the accuracy of ice-water boundary identification and event location from each configuration.

Genetic induction of phosphate toxicity significantly reduces the survival of hypercholesterolemic obese mice

PubMed Central

Ohnishi, Mutsuko; Kato, Shigeko; Razzaque, M. Shawkat

2013-01-01

Objective The adverse effects of metabolic disorders in obesity have been extensively studied; however, the pathologic effects of hyperphosphatemia or phosphate toxicity in obesity have not been studied in similar depth and detail, chiefly because such an association is thought to be uncommon. Studies have established that the incidence of obesity-associated nephropathy is increasing. Because hyperphosphatemia is a major consequence of renal impairment, this study determines the in vivo effects of hyperphosphatemia in obesity. Methods and results We genetically induced hyperphosphatemia in leptin-deficient obese (ob/ob) mice by generating ob/ob and klotho double knockout [ob/ob-klotho−/−] mice. As a control, we made ob/ob mice with hypophosphatemia by generating ob/ob and 1-alpha hydroxylase double knockout [ob/ob-1α(OH)ase−/−] mice. Compared to the wild-type mice, all three obese background mice, namely ob/ob, ob/ob-klotho−/−, and ob/ob-1α(OH)ase−/− mice developed hypercholesterolemia. In addition, the hyperphosphatemic, ob/ob-klotho−/− genetic background induced generalized tissue atrophy and widespread soft-tissue and vascular calcifications, which led to a shorter lifespan; no such changes were observed in the hypophosphatemic, ob/ob-1α(OH)ase−/− mice. Significantly, in contrast to the reduced survival of the ob/ob-klotho−/− mice, lowering serum phosphate levels in ob/ob-1α(OH)ase−/− mice showed no such compromised survival, despite both mice being hypercholesterolemic. Conclusion These genetic manipulation studies suggest phosphate toxicity is an important risk factor in obesity that can adversely affect survival. PMID:22037453

Genetic induction of phosphate toxicity significantly reduces the survival of hypercholesterolemic obese mice.

PubMed

Ohnishi, Mutsuko; Kato, Shigeko; Razzaque, M Shawkat

2011-11-25

The adverse effects of metabolic disorders in obesity have been extensively studied; however, the pathologic effects of hyperphosphatemia or phosphate toxicity in obesity have not been studied in similar depth and detail, chiefly because such an association is thought to be uncommon. Studies have established that the incidence of obesity-associated nephropathy is increasing. Because hyperphosphatemia is a major consequence of renal impairment, this study determines the in vivo effects of hyperphosphatemia in obesity. We genetically induced hyperphosphatemia in leptin-deficient obese (ob/ob) mice by generating ob/ob and klotho double knockout [ob/ob-klotho(-/-)] mice. As a control, we made ob/ob mice with hypophosphatemia by generating ob/ob and 1-alpha hydroxylase double knockout [ob/ob-1α(OH)ase(-/-)] mice. Compared to the wild-type mice, all three obese background mice, namely ob/ob, ob/ob-klotho(-/-), and ob/ob-1α(OH)ase(-/-) mice developed hypercholesterolemia. In addition, the hyperphosphatemic, ob/ob-klotho(-/-) genetic background induced generalized tissue atrophy and widespread soft-tissue and vascular calcifications, which led to a shorter lifespan; no such changes were observed in the hypophosphatemic, ob/ob-1α(OH)ase(-/-) mice. Significantly, in contrast to the reduced survival of the ob/ob-klotho(-/-) mice, lowering serum phosphate levels in ob/ob-1α(OH)ase(-/-) mice showed no such compromised survival, despite both mice being hypercholesterolemic. These genetic manipulation studies suggest phosphate toxicity is an important risk factor in obesity that can adversely affect survival. Copyright © 2011 Elsevier Inc. All rights reserved.

Leptin Reduces the Expression and Increases the Phosphorylation of the Negative Regulators of GLUT4 Traffic TBC1D1 and TBC1D4 in Muscle of ob/ob Mice

PubMed Central

Sáinz, Neira; Rodríguez, Amaia; Catalán, Victoria; Becerril, Sara; Ramírez, Beatriz; Lancha, Andoni; Burgos-Ramos, Emma; Gómez-Ambrosi, Javier; Frühbeck, Gema

2012-01-01

Leptin improves insulin sensitivity in skeletal muscle. Our goal was to determine whether proteins controlling GLUT4 traffic are altered by leptin deficiency and in vivo leptin administration in skeletal muscle of wild type and ob/ob mice. Leptin-deficient ob/ob mice were divided in three groups: control, leptin-treated (1 mg/kg/d) and leptin pair-fed ob/ob mice. Microarray analysis revealed that 1,546 and 1,127 genes were regulated by leptin deficiency and leptin treatment, respectively. Among these, we identified 24 genes involved in intracellular vesicle-mediated transport in ob/ob mice. TBC1 domain family, member 1 (Tbc1d1), a negative regulator of GLUT4 translocation, was up-regulated (P = 0.001) in ob/ob mice as compared to wild types. Importantly, leptin treatment reduced the transcript levels of Tbc1d1 (P<0.001) and Tbc1d4 (P = 0.004) in the leptin-treated ob/ob as compared to pair-fed ob/ob animals. In addition, phosphorylation levels of TBC1D1 and TBC1D4 were enhanced in leptin-treated ob/ob as compared to control ob/ob (P = 0.015 and P = 0.023, respectively) and pair-fed ob/ob (P = 0.036 and P = 0.034, respectively) mice. Despite similar GLUT4 protein expression in wild type and ob/ob groups a different immunolocalization of this protein was evidenced in muscle sections. Leptin treatment increased GLUT4 immunoreactivity in gastrocnemius and extensor digitorum longus sections of leptin-treated ob/ob mice. Moreover, GLUT4 protein detected in immunoprecipitates from TBC1D4 was reduced by leptin replacement compared to control ob/ob (P = 0.013) and pair-fed ob/ob (P = 0.037) mice. Our findings suggest that leptin enhances the intracellular GLUT4 transport in skeletal muscle of ob/ob animals by reducing the expression and activity of the negative regulators of GLUT4 traffic TBC1D1 and TBC1D4. PMID:22253718

Receiver function analysis applied to refraction survey data

NASA Astrophysics Data System (ADS)

Subaru, T.; Kyosuke, O.; Hitoshi, M.

2008-12-01

For the estimation of the thickness of oceanic crust or petrophysical investigation of subsurface material, refraction or reflection seismic exploration is one of the methods frequently practiced. These explorations use four-component (x,y,z component of acceleration and pressure) seismometer, but only compressional wave or vertical component of seismometers tends to be used in the analyses. Hence, it is needed to use shear wave or lateral component of seismograms for more precise investigation to estimate the thickness of oceanic crust. Receiver function is a function at a place that can be used to estimate the depth of velocity interfaces by receiving waves from teleseismic signal including shear wave. Receiver function analysis uses both vertical and horizontal components of seismograms and deconvolves the horizontal with the vertical to estimate the spectral difference of P-S converted waves arriving after the direct P wave. Once the phase information of the receiver function is obtained, then one can estimate the depth of the velocity interface. This analysis has advantage in the estimation of the depth of velocity interface including Mohorovicic discontinuity using two components of seismograms when P-to-S converted waves are generated at the interface. Our study presents results of the preliminary study using synthetic seismograms. First, we use three types of geological models that are composed of a single sediment layer, a crust layer, and a sloped Moho, respectively, for underground sources. The receiver function can estimate the depth and shape of Moho interface precisely for the three models. Second, We applied this method to synthetic refraction survey data generated not by earthquakes but by artificial sources on the ground or sea surface. Compressional seismic waves propagate under the velocity interface and radiate converted shear waves as well as at the other deep underground layer interfaces. However, the receiver function analysis applied to the second model cannot clearly estimate the velocity interface behind S-P converted wave or multi-reflected waves in a sediment layer. One of the causes is that the incidence angles of upcoming waves are too large compared to the underground source model due to the slanted interface. As a result, incident converted shear waves have non-negligible energy contaminating the vertical component of seismometers. Therefore, recorded refraction waves need to be transformed from depth-lateral coordinate into radial-tangential coordinate, and then Ps converted waves can be observed clearly. Finally, we applied the receiver function analysis to a more realistic model. This model has not only similar sloping Mohorovicic discontinuity and surface source locations as second model but the surface water layer. Receivers are aligned on the sea bottom (OBS; Ocean Bottom Seismometer survey case) Due to intricately bounced reflections, simulated seismic section becomes more complex than the other previously-mentioned models. In spite of the complexity in the seismic records, we could pick up the refraction waves from Moho interface, after stacking more than 20 receiver functions independently produced from each shot gather. After these processing, the receiver function analysis is justified as a method to estimate the depths of velocity interfaces and would be the applicable method for refraction wave analysis. The further study will be conducted for more realistic model that contain inhomogeneous sediment model, for example, and finally used in the inversion of the depth of velocity interfaces like Moho.

Design and development of an interferometric readout for planetary seismometers.

NASA Astrophysics Data System (ADS)

Fayon, L.; Lognonne, P. H.; Halloin, H.

2016-12-01

Seismometers are now likely to be placed on other planets. Indeed, 3 Very Broad Band seismometers (VBB) will land on Mars in 2018 (NASA InSight mission) and new projects are considered for a seismic return on the Moon. The Apollo seismometers had at 0.5Hz a resolution of about 0.5Å in ground displacement but were however unable to detect the Lunar ground seismic noise, which has been estimated to be about 1/100 of their resolution at this frequency and is possibly due to the meteoritic hum, e.g. continuous fall of micro-meteorites (Lognonné et al., 2009). Core seismic phases, although detected through stacking, have not also been individually recorded (Weber et al, 2011, Garcia et al., 2011). New generation of broadband seismometers, 100 to 1000 times more sensitive than the Apollo are therefore requested in order to reach this seismic noise floor, in order to take benefit of all the seismic waves generated by the Moon seismic activity. The core of such seismometer will be the proof mass displacement sensors, with extreme improvement in performances, linearity and noise level. We develop such a prototype, based on the use of gravitational waves detectors' technology which are the reference in term of interferometric measurements at low frequency and very low noise levels. The objective is to improve the sensitivity by 2 orders of magnitude compared to the current seismometers performances (e.g. 4pm/√Hz at 1Hz for InSight VBBs) and to reach sensitivities below 50 fm/√Hz at 1Hz). This prototype is based on the Pound-Drever-Hall laser frequency stabilization technique. The principle of the measurement is shown, as well as the implementation considerations.

Effects of Thermal Variability on Broadband Seismometers: Controlled Experiments, Observations, and Implications

NASA Astrophysics Data System (ADS)

Doody, C.; Ringler, A. T.; Anthony, R. E.; Wilson, D.; Holland, A. A.; Hutt, C. R.; Sandoval, L. D.

2017-12-01

Although taking steps to isolate seismic instruments from temperature fluctuations is routine practice within the seismological community, the necessary level of thermal stability required in a broadband installation to avoid generating noise is largely unknown. In order to quantify the temperature sensitivity of seismometers over a broad range of frequencies, we artificially induced local temperature changes on three different models of seismometers to empirically measure the effect of thermal variations on seismometer output. We found that temperature changes above 0.002˚C per day show upwards of 10% change in broadband seismometer amplitude when compared to thermally stable reference measurements. We also find that rises in sensor incoherent self-noise increase with temperature variation; these increases in noise can be modeled as 1/f noise (pink noise). While seismometer output changes that correlate with temperature changes are likely correctable, this increase in 1/f noise is unlikely to be easily corrected for. These experimental results are also compared to data from Global Seismographic Network (GSN)-IRIS/USGS network station TUC (Tucson, Arizona) which is well instrumented with temperature sensors, as well as three different broadband sensors, each of which uses a different method of thermal isolation (i.e. Styrofoam box, 1.2m posthole within the pier, and water bricks). We show that isolating sensors with water bricks, as well as posthole and borehole installations, thermally isolate sensors well enough to remove any thermal variability that would affect their output. We find that better seismometer installations which provide thermal stability below 0.002 ˚C per day could help to improve long-period vertical seismic data across the GSN by decreasing temperature-driven 1/f noise.

Revision of IRIS/IDA Seismic Station Metadata

NASA Astrophysics Data System (ADS)

Xu, W.; Davis, P.; Auerbach, D.; Klimczak, E.

2017-12-01

Trustworthy data quality assurance has always been one of the goals of seismic network operators and data management centers. This task is considerably complex and evolving due to the huge quantities as well as the rapidly changing characteristics and complexities of seismic data. Published metadata usually reflect instrument response characteristics and their accuracies, which includes zero frequency sensitivity for both seismometer and data logger as well as other, frequency-dependent elements. In this work, we are mainly focused studying the variation of the seismometer sensitivity with time of IRIS/IDA seismic recording systems with a goal to improve the metadata accuracy for the history of the network. There are several ways to measure the accuracy of seismometer sensitivity for the seismic stations in service. An effective practice recently developed is to collocate a reference seismometer in proximity to verify the in-situ sensors' calibration. For those stations with a secondary broadband seismometer, IRIS' MUSTANG metric computation system introduced a transfer function metric to reflect two sensors' gain ratios in the microseism frequency band. In addition, a simulation approach based on M2 tidal measurements has been proposed and proven to be effective. In this work, we compare and analyze the results from three different methods, and concluded that the collocated-sensor method is most stable and reliable with the minimum uncertainties all the time. However, for epochs without both the collocated sensor and secondary seismometer, we rely on the analysis results from tide method. For the data since 1992 on IDA stations, we computed over 600 revised seismometer sensitivities for all the IRIS/IDA network calibration epochs. Hopefully further revision procedures will help to guarantee that the data is accurately reflected by the metadata of these stations.

Seismometer reading viewed in ALSEP Room in Misson Control during Apollo 17

NASA Technical Reports Server (NTRS)

1972-01-01

The seismometer readings from the impact made by the Apollo 17 Saturn S-IVB stage when it struck the lunar surface are viewed in the ALSEP Room in the Misson Control Center at Houston by Dr. Maurice Ewing, professor of geophysics of the Universtiy of Texas at Galveston. The seismic tracings are from sensings made by seismometers of Apollo Lunar Surface Experiments Packages left on the Moon during earlier Apollo lunar landing missions.

Seismic switch for strong motion measurement

DOEpatents

Harben, Philip E.; Rodgers, Peter W.; Ewert, Daniel W.

1995-01-01

A seismic switching device that has an input signal from an existing microseismic station seismometer and a signal from a strong motion measuring instrument. The seismic switch monitors the signal level of the strong motion instrument and passes the seismometer signal to the station data telemetry and recording systems. When the strong motion instrument signal level exceeds a user set threshold level, the seismometer signal is switched out and the strong motion signal is passed to the telemetry system. The amount of time the strong motion signal is passed before switching back to the seismometer signal is user controlled between 1 and 15 seconds. If the threshold level is exceeded during a switch time period, the length of time is extended from that instant by one user set time period.

Seismic switch for strong motion measurement

DOEpatents

Harben, P.E.; Rodgers, P.W.; Ewert, D.W.

1995-05-30

A seismic switching device is described that has an input signal from an existing microseismic station seismometer and a signal from a strong motion measuring instrument. The seismic switch monitors the signal level of the strong motion instrument and passes the seismometer signal to the station data telemetry and recording systems. When the strong motion instrument signal level exceeds a user set threshold level, the seismometer signal is switched out and the strong motion signal is passed to the telemetry system. The amount of time the strong motion signal is passed before switching back to the seismometer signal is user controlled between 1 and 15 seconds. If the threshold level is exceeded during a switch time period, the length of time is extended from that instant by one user set time period. 11 figs.

Genetically obese (ob/ob) mice are resistant to the lethal effects of thioacetamide hepatotoxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Won, Young-Suk; Song, Ji-Won; Lim, Jong-Hwan

Obesity increases the risk of chronic liver diseases, including viral hepatitis, alcohol-induced liver disease, and non-alcoholic steatohepatitis. In this study, we investigated the effects of obesity in acute hepatic failure using a murine model of thioacetamide (TA)-induced liver injury. Genetically obese ob/ob mice, together with non-obese ob/+ littermates, were subjected to a single intraperitoneal injection of TA, and examined for signs of hepatic injury. ob/ob mice showed a significantly higher survival rate, lower levels of serum alanine aminotransferase and aspartate aminotransferase, and less hepatic necrosis and apoptosis, compared with ob/+ mice. In addition, ob/ob mice exhibited significantly lower levels ofmore » malondialdehyde and significantly higher levels of glutathione and antioxidant enzyme activities compared with their ob/+ counterparts. Bioactivation analyses revealed reduced plasma clearance of TA and covalent binding of [{sup 14}C]TA to liver macromolecules in ob/ob mice. Together, these data demonstrate that genetically obese mice are resistant to TA-induced acute liver injury through diminished bioactivation of TA and antioxidant effects. - Highlights: • ob/ob mice are resistant to lethal doses of thioacetamide, compared to ob/+ mice. • ob/ob mice show reduced oxidative stress and enhanced antioxidant enzyme activity. • ob/ob mice exhibit diminished bioactivation of thioacetamide.« less

Development of Ocean-Bottom Seismograph in Taiwan

NASA Astrophysics Data System (ADS)

Chang, H.; Jang, J. P.; Chen, P.; Lin, C. R.; Kuo, B. Y.; Wang, C. C.; Kim, K. H.; Lin, P. P.

2016-12-01

Yardbird-20s, one type of Ocean-Bottom Seismograph (OBS), is fabricated by Taiwan Ocean Research Institute (TORI), the Institute of Earth Science of Academia Sinica and the Institute of Undersea Technology of the National Sun Yat-Sen University in Taiwan. Yardbirds can be deployed up to 5000m deep for up to 15 months. The total weight with anchor in the air is about 170Kg. The rising and sinking rate is about 0.8 m/s. We utilized ultra-low power micro control unit (MCU) and SD card to design a data logger. The sensors are three of 4.5Hz geophones that were extended the lower frequency response to 20 sec. The sensor module also includes the leveling system, which is design by dual-axis DC motor-driven module to level the vertical component to be less than 0.1 degree with respect to the gravity. Yardbirds have been successfully deployed and recovered in several research cruises in Taiwan and Korea. In this study, we'll also display the data quality and power spectral density (PSD) calculations, probability density function (PDF) plots and from the Yardbirds that deployed and recovered in the East Sea near sough-east of Korea.

Technology and Engineering Advances Supporting EarthScope's Alaska Transportable Array

NASA Astrophysics Data System (ADS)

Miner, J.; Enders, M.; Busby, R.

2015-12-01

EarthScope's Transportable Array (TA) in Alaska and Canada is an ongoing deployment of 261 high quality broadband seismographs. The Alaska TA is the continuation of the rolling TA/USArray deployment of 400 broadband seismographs in the lower 48 contiguous states and builds on the success of the TA project there. The TA in Alaska and Canada is operated by the IRIS Consortium on behalf of the National Science Foundation as part of the EarthScope program. By Sept 2015, it is anticipated that the TA network in Alaska and Canada will be operating 105 stations. During the summer of 2015, TA field crews comprised of IRIS and HTSI station specialists, as well as representatives from our partner agencies the Alaska Earthquake Center and the Alaska Volcano Observatory and engineers from the UNAVCO Plate Boundary Observatory will have completed a total of 36 new station installations. Additionally, we will have completed upgrades at 9 existing Alaska Earthquake Center stations with borehole seismometers and the adoption of an additional 35 existing stations. Continued development of battery systems using LiFePO4 chemistries, integration of BGAN, Iridium, Cellular and VSAT technologies for real time data transfer, and modifications to electronic systems are a driving force for year two of the Alaska Transportable Array. Station deployment utilizes custom heliportable drills for sensor emplacement in remote regions. The autonomous station design evolution include hardening the sites for Arctic, sub-Arctic and Alpine conditions as well as the integration of rechargeable Lithium Iron Phosphate batteries with traditional AGM batteries We will present new design aspects, outcomes, and lessons learned from past and ongoing deployments, as well as efforts to integrate TA stations with other existing networks in Alaska including the Plate Boundary Observatory and the Alaska Volcano Observatory.

A Low-Cost Energy-Efficient Cableless Geophone Unit for Passive Surface Wave Surveys

PubMed Central

Dai, Kaoshan; Li, Xiaofeng; Lu, Chuan; You, Qingyu; Huang, Zhenhua; Wu, H. Felix

2015-01-01

The passive surface wave survey is a practical, non-invasive seismic exploration method that has increasingly been used in geotechnical engineering. However, in situ deployment of traditional wired geophones is labor intensive for a dense sensor array. Alternatively, stand-alone seismometers can be used, but they are bulky, heavy, and expensive because they are usually designed for long-term monitoring. To better facilitate field applications of the passive surface wave survey, a low-cost energy-efficient geophone system was developed in this study. The hardware design is presented in this paper. To validate the system’s functionality, both laboratory and field experiments were conducted. The unique feature of this newly-developed cableless geophone system allows for rapid field applications of the passive surface wave survey with dense array measurements. PMID:26404270

Ablation of ghrelin receptor in leptin-deficient ob/ob mice has paradoxical effects on glucose homeostasis when compared with ablation of ghrelin in ob/ob mice.

PubMed

Ma, Xiaojun; Lin, Yuezhen; Lin, Ligen; Qin, Guijun; Pereira, Fred A; Haymond, Morey W; Butte, Nancy F; Sun, Yuxiang

2012-08-01

The orexigenic hormone ghrelin is important in diabetes because it has an inhibitory effect on insulin secretion. Ghrelin ablation in leptin-deficient ob/ob (Ghrelin(-/-):ob/ob) mice increases insulin secretion and improves hyperglycemia. The physiologically relevant ghrelin receptor is the growth hormone secretagogue receptor (GHS-R), and GHS-R antagonists are thought to be an effective strategy for treating diabetes. However, since some of ghrelin's effects are independent of GHS-R, we have utilized genetic approaches to determine whether ghrelin's effect on insulin secretion is mediated through GHS-R and whether GHS-R antagonism indeed inhibits insulin secretion. We investigated the effects of GHS-R on glucose homeostasis in Ghsr-ablated ob/ob mice (Ghsr(-/-):ob/ob). Ghsr ablation did not rescue the hyperphagia, obesity, or insulin resistance of ob/ob mice. Surprisingly, Ghsr ablation worsened the hyperglycemia, decreased insulin, and impaired glucose tolerance. Consistently, Ghsr ablation in ob/ob mice upregulated negative β-cell regulators (such as UCP-2, SREBP-1c, ChREBP, and MIF-1) and downregulated positive β-cell regulators (such as HIF-1α, FGF-21, and PDX-1) in whole pancreas; this suggests that Ghsr ablation impairs pancreatic β-cell function in leptin deficiency. Of note, Ghsr ablation in ob/ob mice did not affect the islet size; the average islet size of Ghsr(-/-):ob/ob mice is similar to that of ob/ob mice. In summary, because Ghsr ablation in leptin deficiency impairs insulin secretion and worsens hyperglycemia, this suggests that GHS-R antagonists may actually aggravate diabetes under certain conditions. The paradoxical effects of ghrelin ablation and Ghsr ablation in ob/ob mice highlight the complexity of the ghrelin-signaling pathway.

Extending a Lippmann style seismometer's dynamic range by using a non-linear feedback circuit

NASA Astrophysics Data System (ADS)

Romeo, Giovanni; Spinelli, Giuseppe

2013-04-01

A Lippmann style seismometer uses a single-coil velocity-feedback method in order to extend toward lower frequencies a geophone's frequency response. Strong seismic signals may saturate the electronics, sometimes producing a characteristic whale-shaped recording. Adding a non linear feedback in the electronic circuit may avoid saturation, allowing the strong-motion use of the seismometer without affecting the usual performance. We show results from both simulations and experiments, using a Teledyne Geotech s13 as a mechanical part.

Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data

NASA Astrophysics Data System (ADS)

Chabert, Anne; Minshull, Tim A.; Westbrook, Graham K.; Berndt, Christian; Thatcher, Kate E.; Sarkar, Sudipta

2011-12-01

The ongoing warming of bottom water in the Arctic region is anticipated to destabilize some of the gas hydrate present in shallow seafloor sediment, potentially causing the release of methane from dissociating hydrate into the ocean and the atmosphere. Ocean-bottom seismometer (OBS) experiments were conducted along the continental margin of western Svalbard to quantify the amount of methane present as hydrate or gas beneath the seabed. P- and S-wave velocities were modeled for five sites along the continental margin, using ray-trace forward modeling. Two southern sites were located in the vicinity of a 30 km long zone where methane gas bubbles escaping from the seafloor were observed during the cruise. The three remaining sites were located along an E-W orientated line in the north of the margin. At the deepest northern site, Vp anomalies indicate the presence of hydrate in the sediment immediately overlying a zone containing free gas up to 100-m thick. The acoustic impedance contrast between the two zones forms a bottom-simulating reflector (BSR) at approximately 195 m below the seabed. The two other sites within the gas hydrate stability zone (GHSZ) do not show the clear presence of a BSR or of gas hydrate. However, anomalously low Vp, indicating the presence of free gas, was modeled for both sites. The hydrate content was estimated from Vp and Vs, using effective-medium theory. At the deepest northern site, modeling suggests a pore-space hydrate concentration of 7-12%, if hydrate forms as part of a connected framework, and about 22% if it is pore-filling. At the two other northern sites, located between the deepest site and the landward limit of the GHSZ, we suggest that hydrate is present in the sediment as inclusions. Hydrate may be present in small quantities at these two sites (4-5%) of the pore space. The variation in lithology for the three sites indicated by high-resolution seismic profiles may control the distribution, concentration and formation of hydrate and free gas.

Structure of the Cascadia Subduction Zone Imaged Using Surface Wave Tomography

NASA Astrophysics Data System (ADS)

Schaeffer, A. J.; Audet, P.

2017-12-01

Studies of the complete structure of the Cascadia subduction zone from the ridge to the arc have historically been limited by the lack of offshore ocean bottom seismograph (OBS) infrastructure. On land, numerous dense seismic deployments have illuminated detailed structures and dynamics associated with the interaction between the subducting oceanic plate and the overriding continental plate, including cycling of fluids, serpentinization of the overlying forearc mantle wedge, and the location of the upper surface of the Juan de Fuca plate as it subducts beneath the Pacific Northwest. In the last half-decade, the Cascadia Initiative (CI), along with Neptune (ONC) and several other OBS initiatives, have instrumented both the continental shelf and abyssal plains off shore of the Cascadia subduction zone, facilitating the construction of a complete picture of the subduction zone from ridge to trench and volcanic arc. In this study, we present a preliminary azimuthally anisotropic surface-wave phase-velocity based model of the complete system, capturing both the young, unaltered Juan de Fuca plate from the ridge, to its alteration as it enters the subduction zone, in addition to the overlying continent. This model is constructed from a combination of ambient noise cross-correlations and teleseismic two station interferometry, and combines together concurrently running offshore OBS and onshore stations. We furthermore perform a number of representative 1D depth inversions for shear velocity to categorize the pristine oceanic, subducted oceanic, and continental crust and lithospheric structure. In the future the dispersion dataset will be jointly inverted with receiver functions to constrain a 3D shear-velocity model of the complete region.

Seismic Activity offshore Martinique and Dominique islands (Lesser Antilles subduction zone)

NASA Astrophysics Data System (ADS)

Ruiz Fernandez, Mario; Galve, Audrey; Monfret, Tony; Charvis, Philippe; Laigle, Mireille; Flueh, Ernst; Gallart, Josep; Hello, Yann

2010-05-01

In the framework of the European project Thales was Right, two seismic surveys (Sismantilles II and Obsantilles) were carried out to better constrain the lithospheric structure of the Lesser Antilles subduction zone, its seismic activity and to evaluate the associated seismic hazards. Sismantilles II experiment was conducted in January, 2007 onboard R/V Atalante (IFREMER). A total of 90 OBS belonging to Géoazur, INSU-CNRS and IFM-Geomar were deployed on a regular grid, offshore Antigua, Guadeloupe, Dominique and Martinique islands. During the active part of the survey, more than 2500 km of multichannel seismic profiles were shot along the grid lines. Then the OBS remained on the seafloor continuously recording for the seismic activity for approximately 4 months. On April 2007 Obsantilles experiment, carried out onboard R/V Antea (IRD), was focused on the recovery of those OBS and the redeployment of 28 instruments (Géoazur OBS) off Martinique and Dominica Islands for 4 additional months of continuous recording of the seismicity. This work focuses on the analysis of the seismological data recorded in the southern sector of the study area, offshore Martinique and Dominique. During the two recording periods, extending from January to the end of August 2007, more than 3300 seismic events were detected in this area. Approximately 1100 earthquakes had enough quality to be correctly located. Station corrections, obtained from multichannel seismic profiles, were introduced to each OBS to take in to account the sedimentary cover and better constrain the hypocentral determinations. Results show events located at shallower depths in the northern sector of the array, close to the Tiburon Ridge, where the seismic activity is mainly located between 20 to 40 km depth. In the southern sector, offshore Martinique, hypocenters become deeper, ranging to 60 km depth and dipping to the west. Focal solutions have also been obtained using the P wave polarities of the best azimuthally constrained earthquakes (Gap smaller than 90°). Focal mechanisms also reveal some differences between the northern and southern sector of the array. Whereas in the southern sector most of the analysed events show purely reverse fault solutions, in the northern area events present strike slip and normal fault solutions and could be related to intraplate deformation.

An event database for rotational seismology

NASA Astrophysics Data System (ADS)

Salvermoser, Johannes; Hadziioannou, Celine; Hable, Sarah; Chow, Bryant; Krischer, Lion; Wassermann, Joachim; Igel, Heiner

2016-04-01

The ring laser sensor (G-ring) located at Wettzell, Germany, routinely observes earthquake-induced rotational ground motions around a vertical axis since its installation in 2003. Here we present results from a recently installed event database which is the first that will provide ring laser event data in an open access format. Based on the GCMT event catalogue and some search criteria, seismograms from the ring laser and the collocated broadband seismometer are extracted and processed. The ObsPy-based processing scheme generates plots showing waveform fits between rotation rate and transverse acceleration and extracts characteristic wavefield parameters such as peak ground motions, noise levels, Love wave phase velocities and waveform coherence. For each event, these parameters are stored in a text file (json dictionary) which is easily readable and accessible on the website. The database contains >10000 events starting in 2007 (Mw>4.5). It is updated daily and therefore provides recent events at a time lag of max. 24 hours. The user interface allows to filter events for epoch, magnitude, and source area, whereupon the events are displayed on a zoomable world map. We investigate how well the rotational motions are compatible with the expectations from the surface wave magnitude scale. In addition, the website offers some python source code examples for downloading and processing the openly accessible waveforms.

Crustal structure and mantle transition zone thickness beneath a hydrothermal vent at the ultra-slow spreading Southwest Indian Ridge (49°39'E): a supplementary study based on passive seismic receiver functions

NASA Astrophysics Data System (ADS)

Ruan, Aiguo; Hu, Hao; Li, Jiabiao; Niu, Xiongwei; Wei, Xiaodong; Zhang, Jie; Wang, Aoxing

2017-06-01

As a supplementary study, we used passive seismic data recorded by one ocean bottom seismometer (OBS) station (49°41.8'E) close to a hydrothermal vent (49°39'E) at the Southwest Indian Ridge to invert the crustal structure and mantle transition zone (MTZ) thickness by P-to-S receiver functions to investigate previous active seismic tomographic crustal models and determine the influence of the deep mantle thermal anomaly on seafloor hydrothermal venting at an ultra-slow spreading ridge. The new passive seismic S-wave model shows that the crust has a low velocity layer (2.6 km/s) from 4.0 to 6.0 km below the sea floor, which is interpreted as partial melting. We suggest that the Moho discontinuity at 9.0 km is the bottom of a layer (2-3 km thick); the Moho (at depth of 6-7 km), defined by active seismic P-wave models, is interpreted as a serpentinized front. The velocity spectrum stacking plot made from passive seismic data shows that the 410 discontinuity is depressed by 15 km, the 660 discontinuity is elevated by 18 km, and a positive thermal anomaly between 182 and 237 K is inferred.

GLIMPCE Seismic reflection evidence of deep-crustal and upper-mantle intrusions and magmatic underplating associated with the Midcontinent Rift system of North America

USGS Publications Warehouse

Behrendt, John C.; Hutchinson, D.R.; Lee, M.; Thornber, C.R.; Tréhu, A.; Cannon, W.; Green, A.

1990-01-01

Deep-crustal and Moho reflections, recorded on vertical incidence and wide angle ocean bottom Seismometer (OBS) data in the 1986 GLIMPCE (Great Lakes International Multidisciplinary Program on Crustal Evolution) experiment, provide evidence for magmatic underplating and intrusions within the lower crust and upper mantle contemporaneous with crustal extension in the Midcontinent Rift system at 1100 Ma. The rift fill consists of 20-30 km (7-10 s) of basalt flows, secondary syn-rift volcaniclastic and post-basalt sedimentary rock. Moho reflections recorded in Lake Superior over the Midcontinent Rift system have times from 14-18 s (about 46 km to as great as 58 km) in contrast to times of about 11-13 s (about 36-42 km crustal thickness) beneath the surrounding Great Lakes. The Seismically complex deep-crust to mantle transition zone (30-60 km) in north-central Lake Superior, which is 100 km wider than the rift half-graben, reflects the complicated products of tectonic and magmatic interaction of lower-crustal and mantle components during evolution or shutdown of the aborted Midcontinent Rift. In effect, mantle was changed into crust by lowering Seismic velocity (through intrusion of lower density magmatic rocks) and increasing Moho (about 8.1 km s-1 depth. 

The Capricorn Orogen Passive source Array (COPA) in Western Australia

NASA Astrophysics Data System (ADS)

Gessner, K.; Yuan, H.; Murdie, R.; Dentith, M. C.; Johnson, S.; Brett, J.

2015-12-01

COPA is the passive source component of a multi-method geophysical program aimed at assessing the mineral deposits potential of the Proterozoic Capricorn Orogen. Previous results from the active source surveys, receiver functions and magnetotelluric studies show reworked orogenic crust in the orogen that contrasts with more simple crust in the neighbouring Archean cratons, suggesting progressive and punctuated collisional processes during the final amalgamation of the Western Australian craton. Previous seismic studies are all based on line deployment or single station analyses; therefore it is essential to develop 3D seismic images to test whether these observations are representative for the whole orogen. With a careful design that takes advantage of previous passive source surveys, the current long-term and short-term deployments span an area of approximately 500 x 500 km. The 36-month total deployment can guarantee enough data recording for 3D structure imaging using body wave tomography, ambient noise surface wave tomography and P- and S-wave receiver function Common Conversion Point (CCP) stacking techniques. A successive instrument loan from the ANSIR national instrument pool, provided 34 broadband seismometers that have been deployed in the western half of the orogen since March 2014. We expect approximately 40-km lateral resolution near the surface for the techniques we propose, which due to low frequency nature of earthquake waves will degrade to about 100 km near the base of the cratonic lithosphere, which is expected at depths between 200 to 250 km. Preliminary results from the first half of the COPA deployment will be presented in the light of the hypotheses that 1) distinct crustal blocks can be detected continuously throughout the orogen (using ambient noise/body wave tomography); 2) distinct lithologies are present in the crust and upper mantle across the orogen (using receiver function CCP images); and 3) crustal and lithosphere deformation along craton margins in general follows the "wedge" tectonic model (e.g. subduction of Juvenile blocks under the craton mantle as represented by craton-ward dipping sutures.

Glycerol-3-Phosphate Acyltransferase 1 Deficiency in ob/ob Mice Diminishes Hepatic Steatosis but Does Not Protect Against Insulin Resistance or Obesity

PubMed Central

Wendel, Angela A.; Li, Lei O.; Li, Yue; Cline, Gary W.; Shulman, Gerald I.; Coleman, Rosalind A.

2010-01-01

OBJECTIVE Hepatic steatosis is strongly associated with insulin resistance, but a causal role has not been established. In ob/ob mice, sterol regulatory element binding protein 1 (SREBP1) mediates the induction of steatosis by upregulating target genes, including glycerol-3-phosphate acyltransferase-1 (Gpat1), which catalyzes the first and committed step in the pathway of glycerolipid synthesis. We asked whether ob/ob mice lacking Gpat1 would have reduced hepatic steatosis and improved insulin sensitivity. RESEARCH DESIGN AND METHODS Hepatic lipids, insulin sensitivity, and hepatic insulin signaling were compared in lean (Lep+/?), lean-Gpat1−/−, ob/ob (Lepob/ob), and ob/ob-Gpat1−/− mice. RESULTS Compared with ob/ob mice, the lack of Gpat1 in ob/ob mice reduced hepatic triacylglycerol (TAG) and diacylglycerol (DAG) content 59 and 74%, respectively, but increased acyl-CoA levels. Despite the reduction in hepatic lipids, fasting glucose and insulin concentrations did not improve, and insulin tolerance remained impaired. In both ob/ob and ob/ob-Gpat1−/− mice, insulin resistance was accompanied by elevated hepatic protein kinase C-ε activation and blunted insulin-stimulated Akt activation. CONCLUSIONS These results suggest that decreasing hepatic steatosis alone does not improve insulin resistance, and that factors other than increased hepatic DAG and TAG contribute to hepatic insulin resistance in this genetically obese model. They also show that the SREBP1-mediated induction of hepatic steatosis in ob/ob mice requires Gpat1. PMID:20200319

Effect of leptin administration on myelination in ob/ob mouse cerebrum after birth.

PubMed

Hashimoto, Ryuju; Matsumoto, Akihiro; Udagawa, Jun; Hioki, Kyoji; Otani, Hiroki

2013-01-09

Brain weight and size are known to be reduced in adult leptin-deficient Lep/Lep (OB) mice when compared with the wild-type (+/+) mice (C57BL/6: B6). We here analyzed leptin's effects on myelination by examining morphometrically the myelin sheath (MS) in the cerebrum of postnatal day (P) 14 and P28 OB that had received leptin 1 nmol/capita/day from P7 to P14 or P28 (OB+lep), in comparison with OB and B6. We examined myelin basic protein (MBP) mRNA levels and the differentiation of oligodendrocytes by comparing the number of oligodendrocyte precursor cells (OPCs) and the mature oligodendrocytes in the cerebrum between OB, OB+lep, and B6 on P14 and P28. MBP-mRNA expression was lower in OB than in B6 on P14 and P28. On P14, it was higher in OB+lep than in OB but was still lower than in B6, whereas on P28 it was even higher in OB+lep than in B6. On P28, the radii of myelinated axons were larger in OB than in B6 and OB+lep. The MS on P28 was significantly thinner in OB than in B6, but there was no significant difference between OB and OB+lep. There were significantly fewer mature oligodendrocytes in OB and OB+lep than in B6 on P28, whereas on P14 there were significantly fewer OPCs in OB and OB+lep than in B6. Our results suggested that leptin regulates the myelination of oligodendrocytes and that the replenishment of leptin in OB recovered myelination but did not affect the differentiation of OPCs from P7 to P28.

Role of estrogen receptor signaling in skeletal response to leptin in female ob/ob mice.

PubMed

Turner, Russell T; Philbrick, Kenneth A; Kuah, Amida F; Branscum, Adam J; Iwaniec, Urszula T

2017-06-01

Leptin, critical in regulation of energy metabolism, is also important for normal bone growth, maturation and turnover. Compared to wild type (WT) mice, bone mass is lower in leptin-deficient ob/ob mice. Osteopenia in growing ob/ob mice is due to decreased bone accrual, and is associated with reduced longitudinal bone growth, impaired cancellous bone maturation and increased marrow adipose tissue (MAT). However, leptin deficiency also results in gonadal dysfunction, disrupting production of gonadal hormones which regulate bone growth and turnover. The present study evaluated the role of increased estrogen in mediating the effects of leptin on bone in ob/ob mice. Three-month-old female ob/ob mice were randomized into one of the 3 groups: (1) ob/ob  + vehicle (veh), (2) ob/ob  + leptin (leptin) or (3) ob/ob  + leptin and the potent estrogen receptor antagonist ICI 182,780 (leptin + ICI). Age-matched WT mice received vehicle. Leptin (40 µg/mouse, daily) and ICI (10 µg/mouse, 2×/week) were administered by subcutaneous injection for 1 month and bone analyzed by X-ray absorptiometry, microcomputed tomography and static and dynamic histomorphometry. Uterine weight did not differ between ob/ob mice and ob/ob mice receiving leptin + ICI, indicating that ICI successfully blocked the uterine response to leptin-induced increases in estrogen levels. Compared to leptin-treated ob/ob mice, ob/ob mice receiving leptin + ICI had lower uterine weight; did not differ in weight loss, MAT or bone formation rate; and had higher longitudinal bone growth rate and cancellous bone volume fraction. We conclude that increased estrogen signaling following leptin treatment is dispensable for the positive actions of leptin on bone and may attenuate leptin-induced bone growth. © 2017 Society for Endocrinology.

Characterization of H/V Spectral Ratios for the Assessment of Slope Stability in the Gas Hydrate-rich Area: an Example from Offshore SW Taiwan

NASA Astrophysics Data System (ADS)

Lin, J. Y.; Tsia, C. H.; Cheng, W. B.; Chin, S. J.; Lin, S. S.; Liang, C. W.

2015-12-01

The Nakamura's method, which calculates the ratios between horizontal and vertical component spectra of seismic signals (H/V), is widely used in the inland area. However, few related estimations were performed for the offshore area and little knowledge for the marine sediments were obtained. From 2013 to 2015, three passive ocean bottom seismometer (OBS) experiments were conducted in gas hydrate-rich area offshore SW Taiwan in the aim of acquiring information related to the physical properties of seafloor sediments. The H/V of the seafloor sediments in the three areas were estimated by using the ambient noise and seismic signal recorded by OBSs. The resonance frequency of each site was estimated from the main peak of H/V distribution and a range between 5 and 10 Hz were obtained. Based on the empirical law, this resonance frequency range should correspond to a sediment thickness of approximately several to ten of meters. This estimation is consistent with the thickness of the sedimentary cover imaged by chirp sonar survey, suggesting that the site response of seafloor is dominantly controlled by the unconsolidated sedimentary layer on the top of the sea bed. Remarkably, the H/V ratios obtained in our study area are much larger than that calculated for the inland areas. The magnification can reach as high as 50 to more than 100. This observation infers that the sea water movement might emphasize the horizontal motion of the marine sediments, which is crucial for the slope stability assessment. Moreover, for most stations located in the active margin, no distinct peak is observed for the H/V pattern calculated during earthquakes. However, in the passive margin, the H/V peak calculated from ambient noise and earthquakes is mostly identical. This phenomenon may suggest that relatively unclear sedimentary boundary exist in the active margin environment. Estimating H/V spectral ratios of data recorded by the OBSs deployed in the southwest Taiwan offshore area offers a general understanding of the preferential vibration modes of seafloor sediment systems. By comparing the resonance characteristics of each site and the chirp sonar profiles, we hope to provide precious information for the designing of marine structures such as oil drilling and production platforms.

Rapid Seismic Deployment for Capturing Aftershocks of the September 2017 Tehuantepec, Mexico (M=8.1) and Morelos-Puebla (M=7.1), Mexico Earthquakes

NASA Astrophysics Data System (ADS)

Velasco, A. A.; Karplus, M. S.; Dena, O.; Gonzalez-Huizar, H.; Husker, A. L.; Perez-Campos, X.; Calo, M.; Valdes, C. M.

2017-12-01

The September 7 Tehuantepec, Mexico (M=8.1) and the September 19 Morelos-Puebla, Mexico (M=7.1) earthquakes ruptured with extensional faulting within the Cocos Plate at 70-km and 50-km depth, as it subducts beneath the continental North American Plate. Both earthquakes caused significant damage and loss of life. These events were followed by a M=6.1 extensional earthquake at only 10-km depth in Oaxaca on September 23, 2017. While the Morelos-Puebla earthquake was likely too far away to be statically triggered by the Tehuantepec earthquake, initial Coulomb stress analyses show that the M=6.1 event may have been an aftershock of the Tehuantepec earthquake. Many questions remain about these earthquakes, including: Did the Cocos Plate earthquakes load the upper plate, and could they possibly trigger an equal or larger earthquake on the plate interface? Are these the result of plate bending? Do the aftershocks migrate to the locked zone in the subduction zone? Why did the intermediate depth earthquakes create so much damage? Are these earthquakes linked by dynamic stresses? Is it possible that a potential slow-slip event triggered both events? To address some of these questions, we deployed 10 broadband seismometers near the epicenter of the Tehuantepec, Mexico earthquake and 51 UTEP-owned nodes (5-Hz, 3-component geophones) to record aftershocks and augment networks deployed by the Universidad Nacional Autónoma de México (UNAM). The 10 broadband instruments will be deployed for 6 months, while the nodes were deployed 25 days. The relative ease-of-deployment and larger numbers of the nodes allowed us to deploy them quickly in the area near the M=6.1 Oaxaca earthquake, just a few days after that earthquake struck. We deployed them near the heavily-damaged cities of Juchitan, Ixtaltepec, and Ixtepec as well as in Tehuantepec and Salina Cruz, Oaxaca in order to test their capabilities for site characterization and aftershock studies. This is the first test of these instruments in a region heavily affected by aftershocks, outside of Oklahoma. Analysis of the nodal and broadband data will allow us to investigate fault geometries from aftershock locations, stress release and orientation from the determination of fault plane solutions, and site effects and characteristics in regions of extensive damage.

The orphan nuclear receptor small heterodimer partner is required for thiazolidinedione effects in leptin-deficient mice.

PubMed

Tseng, Hsiu-Ting; Park, Young Joo; Lee, Yoon Kwang; Moore, David D

2015-05-08

Small heterodimer partner (SHP, NR0B2) is involved in diverse metabolic pathways, including hepatic bile acid, lipid and glucose homeostasis, and has been implicated in effects on the peroxisome proliferator-activated receptor γ (PPARγ), a master regulator of adipogenesis and the receptor for antidiabetic drugs thiazolidinediones (TZDs). In this study, we aim to investigate the role of SHP in TZD response by comparing TZD-treated leptin-deficient (ob/ob) and leptin-, SHP-deficient (ob/ob;Shp(-/-)) double mutant mice. Both ob/ob and double mutant ob/ob;Shp(-/-) mice developed hyperglycemia, insulin resistance, and hyperlipidemia, but hepatic fat accumulation was decreased in the double mutant ob/ob;Shp(-/-) mice. PPARγ2 mRNA levels were markedly lower in ob/ob;Shp(-/-) liver and decreased to a lesser extent in adipose tissue. The TZD troglitazone did not reduce glucose or circulating triglyceride levels in ob/ob;Shp(-/-) mice. Expression of the adipocytokines, such as adiponectin and resistin, was not stimulated by troglitazone treatment. Expression of hepatic lipogenic genes was also reduced in ob/ob;Shp(-/-) mice. Moreover, overexpression of SHP by adenovirus infection increased PPARγ2 mRNA levels in mouse primary hepatocytes. Our results suggest that SHP is required for both antidiabetic and hypolipidemic effects of TZDs in ob/ob mice through regulation of PPARγ expression.

Ablation of ghrelin receptor in leptin-deficient ob/ob mice has paradoxical effects on glucose homeostasis when compared with ablation of ghrelin in ob/ob mice

USDA-ARS?s Scientific Manuscript database

The orexigenic hormone ghrelin is important in diabetes because it has an inhibitory effect on insulin secretion. Ghrelin ablation in leptin-deficient ob/ob (Ghrelin(-/-):ob/ob) mice increases insulin secretion and improves hyperglycemia. The physiologically relevant ghrelin receptor is the growth ...

Microseismicity Linked to Gas Migration and Leakage on the Western Svalbard Shelf

NASA Astrophysics Data System (ADS)

Franek, Peter; Plaza-Faverola, Andreia; Mienert, Jürgen; Buenz, Stefan; Ferré, Bénédicte; Hubbard, Alun

2017-12-01

The continental margin off Prins Karls Forland, western Svalbard, is characterized by widespread natural gas seepage into the water column at and upslope of the gas hydrate stability zone. We deployed an ocean bottom seismometer integrated into the MASOX (Monitoring Arctic Seafloor-Ocean Exchange) automated seabed observatory at the pinch-out of this zone at 389 m water depth to investigate passive seismicity over a continuous 297 day period from 13 October 2010. An automated triggering algorithm was applied to detect over 220,000 short duration events (SDEs) defined as having a duration of less than 1 s. The analysis reveals two different types of SDEs, each with a distinctive characteristic seismic signature. We infer that the first type consists of vocal signals generated by moving mammals, likely finback whales. The second type corresponds to signals with a source within a few hundred meters of the seismometer, either due east or west, that vary on short (˜tens of days) and seasonal time scales. Based on evidence of prevalent seafloor seepage and subseafloor gas accumulations, we hypothesize that the second type of SDEs is related to subseafloor fluid migration and gas seepage. Furthermore, we postulate that the observed temporal variations in microseismicity are driven by transient fluid release and due to the dynamics of thermally forced, seasonal gas hydrate decomposition. Our analysis presents a novel technique for monitoring the duration, intensity, and periodicity of fluid migration and seepage at the seabed and can help elucidate the environmental controls on gas hydrate decomposition and release.

Distinguishing between stress-induced and structural anisotropy at Mount Ruapehu volcano, New Zealand

USGS Publications Warehouse

Johnson, J. H.; Savage, M.K.; Townend, J.

2011-01-01

We have created a benchmark of spatial variations in shear wave anisotropy around Mount Ruapehu, New Zealand, against which to measure future temporal changes. Anisotropy in the crust is often assumed to be caused by stress-aligned microcracks, and the polarization of the fast quasi-shear wave (??) is thus interpreted to indicate the direction of maximum horizontal stress, but can also be due to aligned minerals or macroscopic fractures. Changes in seismic anisotropy have been observed following a major eruption in 1995/96 and were attributed to changes in stress from the depressurization of the magmatic system. Three-component broadband seismometers have been deployed to complement the permanent stations that surround Ruapehu, creating a combined network of 34 three-component seismometers. This denser observational network improves the resolution with which spatial variations in seismic anisotropy can be examined. Using an automated shear wave splitting analysis, we examine local earthquakes in 2008. We observe a strong azimuthal dependence of ?? and so introduce a spatial averaging technique and two-dimensional tomography of recorded delay times. The anisotropy can be divided into regions in which ?? agrees with stress estimations from focal mechanism inversions, suggesting stress-induced anisotropy, and those in which ?? is aligned with structural features such as faults, suggesting structural anisotropy. The pattern of anisotropy that is inferred to be stress related cannot be modeled adequately using Coulomb modeling with a dike-like inflation source. We suggest that the stress-induced anisotropy is affected by loading of the volcano and a lithospheric discontinuity. Copyright 2011 by the American Geophysical Union.

Roselle is cardioprotective in diet-induced obesity rat model with myocardial infarction.

PubMed

Si, Lislivia Yiang-Nee; Ali, Siti Aishah Mohd; Latip, Jalifah; Fauzi, Norsyahida Mohd; Budin, Siti Balkis; Zainalabidin, Satirah

2017-12-15

Obesity increase the risks of hypertension and myocardial infarction (MI) mediated by oxidative stress. This study was undertaken to investigate the actions of roselle aqueous extract (R) on cardiotoxicity in obese (OB) rats and thereon OB rats subjected to MI. Male Sprague-Dawley rats were fed with either normal diet or high-fat diet for 8weeks. Firstly, OB rats were divided into (1) OB and (2) OB+R (100mg/kg, p.o, 28days). Then, OB rats were subjected to MI (ISO, 85mg/kg, s.c, 2days) and divided into three groups: (1) OB+MI, (2) OB+MI+R and (3) OB+MI+enalapril for another 4weeks. Roselle ameliorated OB and OB+MI's cardiac systolic dysfunction and reduced cardiac hypertrophy and fibrosis. The increased oxidative markers and decreased antioxidant enzymes in OB and OB+MI groups were all attenuated by roselle. These observations indicate the protective effect of roselle on cardiac dysfunction in OB and OB+MI rats, which suggest its potential to be developed as a nutraceutical product for obese and obese patients with MI in the future. Copyright © 2017 Elsevier Inc. All rights reserved.

Housing a Raspberry Pi Connected AS-1 Seismometer in a Solar-Paneled Shed

NASA Astrophysics Data System (ADS)

Marton, F.; Tokman, T. L.; Echreshzadeh, M.; Palaric, K. D.; Filippone, N. V.; Sivo, J.

2016-12-01

Last year, students working on the SeismoSTEM project at Bergen Community College successfully manufactured and assembled an AS-1 seismometer1. However, issues students encountered were not knowing where to place the TC-1 and AS-1 seismometers, nor how to configure the instruments with a computer for monitoring and measuring earthquakes. Our solution was to purchase a Raspberry Pi 3 model B, which has four USB ports and a Wi-Fi adapter. We then installed the Raspbian operating system that can run jAmaSeis, which allows for the collection and analysis of seismic data. In terms of the shed that was constructed last summer2, we installed roof shingles, as well as a ventilation system to prevent overheating. The seismometers will then be placed on a concrete slab. In the future, we plan on applying a wood varnish around the exterior of the shed, as well as gravel around the shed for water drainage as well as to make it more visually appealing. Moreover, we plan on mounting a 170-W solar panel on the roof to charge a 12-V deep cycle marine battery, which will provide electricity to the system. References: 1Tokman, T.L. et al., What's shaking? Manufacturing & assembling an AS-1 educational seismometer for undergraduate stem research, Geological Society of America Abstracts with Programs. Vol. 47, No. 7, p.524, 2015. 2Palaric, K.D., et al., Constructing a solar-powered seismic station for educational seismometers, Geological Society of America Abstracts with Programs. Vol. 47, No. 7, p.524, 2015.

Upper crustal structure of Madeira Island revealed from ambient noise tomography

NASA Astrophysics Data System (ADS)

Matos, Catarina; Silveira, Graça; Matias, Luís; Caldeira, Rita; Ribeiro, M. Luísa; Dias, Nuno A.; Krüger, Frank; Bento dos Santos, Telmo

2015-06-01

We present the first image of the Madeira upper crustal structure, using ambient seismic noise tomography. 16 months of ambient noise, recorded in a dense network of 26 seismometers deployed across Madeira, allowed reconstructing Rayleigh wave Green's functions between receivers. Dispersion analysis was performed in the short period band from 1.0 to 4.0 s. Group velocity measurements were regionalized to obtain 2D tomographic images, with a lateral resolution of 2.0 km in central Madeira. Afterwards, the dispersion curves, extracted from each cell of the 2D group velocity maps, were inverted as a function of depth to obtain a 3D shear wave velocity model of the upper crust, from the surface to a depth of 2.0 km. The obtained 3D velocity model reveals features throughout the island that correlates well with surface geology and island evolution.

On the use of volumetric strain meters to infer additional characteristics of short-period seismic radiation

USGS Publications Warehouse

Borcherdt, R.D.; Johnston, M.J.S.; Glassmoyer, G.

1989-01-01

Volumetric strain meters (Sacks-Evertson design) are installed at 15 sites along the San Andreas fault system, to monitor long-term strain changes for earthquake prediction. Deployment of portable broadband, high-resolution digital recorders (GEOS) at several of the sites extends the detection band for volumetric strain to periods shorter than 5 ?? 10-2 sec and permits the simultaneous observation of seismic radiation fields using conventional short-period pendulum seismometers. Recordings of local and regional earthquakes indicate that dilatometers respond to P energy but not direct shear energy and that straingrams can be used to resolve superimposed reflect P and S waves for inference of wave characteristics not permitted by either sensor alone. Simultaneous measurements of incident P- and S-wave amplitudes are used to introduce a technique for single-station estimates of wave field inhomogeneity, free-surface reflection coefficients and local material P velocity. -from Authors

Seismic and infrasonic signals associated with an unusual collapse event at the Soufrière Hills volcano, Montserrat

NASA Astrophysics Data System (ADS)

Green, D. N.; Neuberg, J.

2005-04-01

In March 2004, during a period of no magma extrusion at Soufrière Hills volcano, Montserrat, an explosive event occurred with little precursory activity. Recorded broadband seismic signals ranged from an ultra-long-period signal with a dominant period of 120 s to impulsive, short-duration events containing frequencies up to 30 Hz. Synthetic displacement functions were fit to the long-period data after application of the seismometer response. These indicate a shallow collapse of the volcanic edifice occurred, initiated ~300 m below the surface, lasting ~100 s. Infrasonic tremor and pulses were also recorded in the 1-20 Hz range. The high-frequency seismicity and infrasound are interpreted as the subsequent collapse of a gravitationally unstable buttress of remnant dome material which impacted upon the edifice surface. This unique dataset demonstrates the benefits of deploying multi-parameter stations equipped with broadband instruments.

The Coso geothermal area: A laboratory for advanced MEQ studies for geothermal monitoring

USGS Publications Warehouse

Julian, B.R.; Foulger, G.R.; Richards-Dinger, K.

2004-01-01

The permanent 16-station network of three-component digital seismometers at the Coso geothermal area, California, supplemented by 14 temporary instruments deployed in connection with the DOE Enhanced Geothermal Systems (EGS) Project, provides high-quality microearthquake (MEQ) recordings that are well suited to monitoring a producing geothermal area. We are currently using these data to investigate structure and active processes within the geothermal reservoir by applying three advanced methods: a) high-precision MEQ hypocenter location; b) time-dependent tomography; c) complete (moment tensor) MEQ source mechanism determination. Preliminary results to date resolve seismogenic structures in the producing field more clearly than is possible with conventional earthquake-location techniques. A shallow part of the producing field shows clear changes in the ratio of the seismic wave speeds, Vp/V s, between 1996 and 2002, which are probably related to physical changes in the reservoir caused by fluid extraction.

The MOBB experiment: A prototype permanent off-shore ocean bottom broadband station

NASA Astrophysics Data System (ADS)

Romanowicz, Barbara; Stakes, Debra; Uhrhammer, Robert; McGill, Paul; Neuhauser, Doug; Ramirez, Tony; Dolenc, David

Technical accomplishments of the past 10 years in the design and deployment of sea floor broadband seismic systems are now making it possible to start addressing the issue of the limited coverage of the Earth that can be achieved through land-based installations, at the regional or global scale. In particular, the September 2002 Ocean Mantle Dynamics (OMD) workshop in Snowbird, Utah [OMD Workshop Committee, 2003] proposed the development of two “leap-frogging arrays” of about 30 broadband sea floor instruments to fill geophysically important target holes in ocean coverage for deployment periods of 1 to 2 years. The rationale for an off-shore (“Webfoot”) component of the SArray/Earth-scope “Bigfoot” array was also highlighted at this meeting, pointing out that the study of the North American continent should not stop at the ocean margin.The ocean floor environment is challenging for broadband seismology for several reasons. Broadband seismometers cannot be simply “dropped off” a ship with the expectation that they will produce useable data, particularly on the horizontal components. Several pilot experiments, [e.g., Montagner et al., 1994; OSN1, 1998; Suyehiro et al., 2002] have addressed the issue of optimal installation of ocean bottom stations, and in particular, have carried out comparisons between borehole, sea floor, and buried sea floor installations.

Local Seismicity of the Rainbow Massif on the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Horning, G.; Sohn, R. A.; Canales, J. P.; Dunn, R. A.

2018-02-01

The Rainbow massif, an oceanic core complex located in a nontransform discontinuity on the Mid-Atlantic Ridge (36°N), is notable for hosting high-temperature hydrothermal discharge through ultramafic rocks. Here we report results from a 9 month microearthquake survey conducted with a network of 13 ocean bottom seismometers deployed on and around the Rainbow massif as part of the MARINER experiment in 2013-2014. High rates ( 300 per day) of low-magnitude (average ML 0.5) microearthquakes were detected beneath the massif. The hypocenters do not cluster along deeply penetrating fault surfaces and do not exhibit mainshock/aftershock sequences, supporting the hypothesis that the faulting associated with the exhumation of the massif is currently inactive. Instead, the hypocenters demarcate a diffuse zone of continuous, low-magnitude deformation at relatively shallow (< 3 km) depths beneath the massif, sandwiched in between the seafloor and seismic reflectors interpreted to be magmatic sills driving hydrothermal convection. Most of the seismicity is located in regions where seismic refraction data indicate serpentinized ultramafic host rock, and although the seismic network we deployed was not capable of constraining the focal mechanism of most events, our analysis suggests that serpentinization may play an important role in microearthquake generation at the Rainbow massif.

Nonlinear Geometric and Differential Geometric Guidance of UAVs with Vision Sensing for Reactive Obstacle Avoidance

DTIC Science & Technology

2010-09-29

1 1 1 2 2 2ˆ ˆ ˆ ˆ ˆ ˆˆ ˆ ˆ ˆ0 0 0 0 0 0 0 0 0 0 T r ob ob ob ob ob ob tr tr trX r r rθ φ θ φ θ φ= (3.28) 29...ˆ ˆ ˆ ˆˆ ˆ ˆ0 0 0 0 0 0 0 T r ob ob ob tr tr trX r rθ φ θ φ⎡ ⎤= ⎣ ⎦ (3.29) Since obstacles are assumed to be point obstacles, it

Wide-angle seismic recordings from the 1998 Seismic Hazards Investigation of Puget Sound (SHIPS), western Washington and British Columbia

USGS Publications Warehouse

Brocher, Thomas M.; Parsons, Tom; Creager, Ken C.; Crosson, Robert S.; Symons, Neill P.; Spence, George D.; Zelt, Barry C.; Hammer, Philip T.C.; Hyndman, Roy D.; Mosher, David C.; Tréhu, Anne M.; Miller, Kate C.; ten Brink, Uri S.; Fisher, Michael A.; Pratt, Thomas L.; Alvarez, Marcos G.; Beaudoin, Bruce C.; Louden, Keith E.; Weaver, Craig S.

1999-01-01

This report describes the acquisition and processing of deep-crustal wide-angle seismic reflection and refraction data obtained in the vicinity of Puget Lowland, the Strait of Juan de Fuca, and Georgia Strait, western Washington and southwestern British Columbia, in March 1998 during the Seismic Hazards Investigation of Puget Sound (SHIPS). As part of a larger initiative to better understand lateral variations in crustal structure along the Cascadia margin, SHIPS participants acquired 1000 km of deep-crustal multichannel seismic-reflection profiles and 1300 km of wideangle airgun shot lines in this region using the R/V Thompson and R/V Tully. The Tully was used to record airgun shots fired by the Thompson in two different geometries: (1) expanding spread profiles (ESPs) and (2) constant offset profiles (COPs). Prior to this reflection survey, we deployed 257 Reftek and 15 ocean-bottom seismic recorders to record the airgun signals at far offsets. All data were recorded digitally on large-capacity hard disks. Although most of these stations only recorded the vertical component of motion, 95 of these seismographs recorded signals from an oriented 3-component seismometer. By recording signals generated by the Thompson's marine air gun array, operated in two differing geometries having a total volume of 110 and 79 liters (6730 and 4838 cu. in.), respectively, the arrays of wide-angle recorders were designed to (1) image the crustal structure, particularly in the vicinity of crustal faults and Cenozoic sedimentary basins, (2) determine the geometry of the Moho, and (3) image the subducting Gorda and Juan de Fuca plates. Nearly 33,300 air gun shots were recorded along several seismic lines. In this report, we illustrate the expanding spread profiles acquired using the Thompson and Tully, describe the land and ocean-bottom recording of the air gun signals, discuss the processing of the land recorder data into common receiver gathers, and illustrate the processed wide-angle seismic data collected using the Refteks and ocean-bottom seismometers. We also describe the format and content of the archival tapes containing the SEGY-formated, common-receiver gathers for the Reftek data. Data quality is variable but SHIPS appears to have successfully obtained useful data from almost all the stations deployed to record the airgun shots. Several interesting arrivals were observed: including refractions from the sedimentary basin fill in several basins, refractions from basement rocks forming the upper crust, Pg, refractions from the upper mantle, Pn, as well as reflections from within the crust and from the top of the upper mantle, PmP. We separately archived more than 30 local earthquakes recorded by the Reftek array during our deployment.

Temperature dependence of O2 consumption; opposite effects of leptin and etomoxir on respiratory quotient in mice.

PubMed

Högberg, Helena; Engblom, Lars; Ekdahl, Asa; Lidell, Veronica; Walum, Erik; Alberts, Peteris

2006-04-01

The aims were to compare the temperature dependence of the metabolic rate in young ob/ob mice with that in mature ob/ob and db/db mice and to examine the effect on the metabolic substrate preference of leptin and etomoxir in ob/ob, C57BL/6J (wild-type), and db/db mice. In vivo oxygen consumption and carbon dioxide production were continuously measured by indirect calorimetry, and body temperature and total locomotor activity were measured by an implanted transponder. Leptin, etomoxir, or vehicle was administered intraperitoneally. The temperature dependence of the metabolic rate of mature ob/ob and db/db mice were similar to that in wild-type mice. In young 6-week-old ob/ob mice, the metabolic rate was almost doubled at 15 degrees C. Leptin (2 x 3 mg/kg) decreased the respiratory quotient (RQ) and carbon dioxide production but did not alter oxygen consumption, body temperature, or locomotor activity in ob/ob and C57BL/6J mice and had no effect in the db/db mice. Etomoxir (2 x 30 mg/kg) enhanced RQ and decreased oxygen consumption, carbon dioxide production, and body temperature in ob/ob, C57BL/6J, and db/db mice. Total locomotor activity was reduced in ob/ob and C57BL/6J mice. In young ob/ob mice, the temperature sensitivity was enhanced compared with mature mice. Leptin and etomoxir had opposite effects on metabolic substrate preference. Leptin and lowered environmental temperature increased the relative fat oxidation as indicated by decreased RQ, possibly through activation of the sympathetic nervous system.

Thermogenesis, fatty acid synthesis with oxidation, and inflammation in the brown adipose tissue of ob/ob (-/-) mice.

PubMed

Martins, Fabiane Ferreira; Bargut, Thereza Cristina Lonzetti; Aguila, Marcia Barbosa; Mandarim-de-Lacerda, Carlos Alberto

2017-03-01

Brown adipose tissue (BAT) is specialized in heat production, but its metabolism in ob/ob mice is still a matter of debate. We aimed to verify ob/ob mice BAT using C57Bl/6 male mice (as the wild-type, WT) and leptin-deficient ob/ob mice (on the C57Bl/6 background strain), at three months of age (n=10/group). At euthanasia, animals had their interscapular BAT weighed, and prepared for analysis (Western blot, and RT-qPCR). In comparison with the WT group, the ob/ob group showed reduced thermogenic signaling markers (gene expression of beta 3-adrenergic receptor, beta3-AR; PPARgamma coactivator 1 alpha, PGC1alpha, and uncoupling protein 1, UCP1). The ob/ob group also showed impaired gene expression for lipid utilization (perilipin was increased, while other markers were diminished: carnitine palmitoyltransferase-1b, CPT-1b; cluster of differentiation 36, CD36; fatty acid binding protein 4, FABP4; fatty acid synthase, FAS, and sterol regulatory element-binding protein 1c, SREBP1c), and altered protein expression of insulin signaling (diminished pAKT, TC10, and GLUT-4). Lastly, the ob/ob group showed increased gene expression of markers of inflammation (interleukin 1 beta, IL-1beta; IL-6, tumor necrosis factor alpha, TNFalpha; and monocyte chemotactic protein-1, MCP-1). In conclusion, the ob/ob mice have decreased thermogenic markers associated with reduced gene expression related to fatty acid synthesis, mobilization, and oxidation. There were also alterations in insulin signaling and protein and gene expressions of inflammation. The findings suggest that the lack of substrate for thermogenesis and the local inflammation negatively regulated thermogenic signaling in the ob/ob mice. Copyright © 2016 Elsevier GmbH. All rights reserved.

Improvements in absolute seismometer sensitivity calibration using local earth gravity measurements

USGS Publications Warehouse

Anthony, Robert E.; Ringler, Adam; Wilson, David

2018-01-01

The ability to determine both absolute and relative seismic amplitudes is fundamentally limited by the accuracy and precision with which scientists are able to calibrate seismometer sensitivities and characterize their response. Currently, across the Global Seismic Network (GSN), errors in midband sensitivity exceed 3% at the 95% confidence interval and are the least‐constrained response parameter in seismic recording systems. We explore a new methodology utilizing precise absolute Earth gravity measurements to determine the midband sensitivity of seismic instruments. We first determine the absolute sensitivity of Kinemetrics EpiSensor accelerometers to 0.06% at the 99% confidence interval by inverting them in a known gravity field at the Albuquerque Seismological Laboratory (ASL). After the accelerometer is calibrated, we install it in its normal configuration next to broadband seismometers and subject the sensors to identical ground motions to perform relative calibrations of the broadband sensors. Using this technique, we are able to determine the absolute midband sensitivity of the vertical components of Nanometrics Trillium Compact seismometers to within 0.11% and Streckeisen STS‐2 seismometers to within 0.14% at the 99% confidence interval. The technique enables absolute calibrations from first principles that are traceable to National Institute of Standards and Technology (NIST) measurements while providing nearly an order of magnitude more precision than step‐table calibrations.

Hormone-sensitive lipase deficiency suppresses insulin secretion from pancreatic islets of Lep{sup ob/ob} mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sekiya, Motohiro; Yahagi, Naoya, E-mail: nyahagi-tky@umin.ac.jp; Laboratory of Molecular Physiology on Energy Metabolism, Graduate School of Medicine, University of Tokyo, Tokyo 113-8655

2009-09-25

It has long been a matter of debate whether the hormone-sensitive lipase (HSL)-mediated lipolysis in pancreatic {beta}-cells can affect insulin secretion through the alteration of lipotoxicity. We generated mice lacking both leptin and HSL (Lep{sup ob/ob}/HSL{sup -/-}) and explored the role of HSL in pancreatic {beta}-cells in the setting of obesity. Lep{sup ob/ob}/HSL{sup -/-} developed elevated blood glucose levels and reduced plasma insulin levels compared with Lep{sup ob/ob}/HSL{sup +/+} in a fed state, while the deficiency of HSL did not affect glucose homeostasis in Lep{sup +/+} background. The deficiency of HSL exacerbated the accumulation of triglycerides in Lep{sup ob/ob} islets,more » leading to reduced glucose-stimulated insulin secretion. The deficiency of HSL also diminished the islet mass in Lep{sup ob/ob} mice due to decreased cell proliferation. In conclusion, HSL affects insulin secretary capacity especially in the setting of obesity.« less

Energy balance in adrenalectomized ob/ob mice: effects of dietary starch and glucose.

PubMed

Warwick, B P; Romsos, D R

1988-07-01

Effects of different carbohydrate types on energy balance, fatty acid synthesis, and plasma insulin concentrations in adrenalectomized ob/ob mice were investigated. Obese (ob/ob) and lean mice adrenalectomized at 4 wk of age received one of four high-carbohydrate powdered diets for 3 wk: stock, glucose, starch, or starch plus wheat bran. Adrenalectomy reduced energy intake of ob/ob mice equally independent of diet type, whereas energetic efficiency, in vivo rates of fatty acid synthesis in liver and white adipose tissue, and plasma insulin concentrations were substantially reduced to approach values in lean mice in all adrenalectomized ob/ob mice except those fed glucose. The ability of adrenalectomy to normalize energy balance in ob/ob mice depends on factors other than the reduced circulating concentration of glucocorticoids alone. Diet composition is a crucial factor, and striking differences exist between semipurified diets containing a simple sugar (glucose) and those containing a complex carbohydrate (starch), with no additional effect of dietary fiber (wheat bran).

Waveforms clustering of small magnitude earthquakes recorded in the Northern Sicilian offshore: evidence of multiplets

NASA Astrophysics Data System (ADS)

D'Alessandro, A.; Mangano, G.; D'Anna, G.; Luzio, D.; Selvaggi, G.

2011-12-01

On September 6th 2002 the northern Sicily was hit by a strong earthquake (MW 5.9). In the following six months over a thousand aftershocks were located in the same area. On December 7th 2009, the INGV OBSLab deployed an OBS/H near the epicentral area of the main shock at a depth of 1500 m. The submarine station was recovered after 233 days. During the eight months of the experiment the OBS/H recorded about 250 small magnitude events of clear local origin. In order to identify seismic events generated by the same tectonic structure, we have applied a clustering technique based on the similarity of the waveforms. The similarity matrix was constructed using the maximum of the normalized cross-covariance function. To identify the multiplets, we used a clustering technique based on an agglomerative hierarchical algorithm, based on the nearest neighbor strategy. The results were summarized in the dendrogram of Fig. 1. The partitions have been obtained by "cutting" the dendrogram at a level of distance equal to 0.3. So we have identified 9 multiplets and some doublets and triplets. Fig. 2 shows as example the multiplet 1. The events of this cluster have a high level of similarity; 25 of the 31 micro-events are characterized by a similarity greater than 0.9. In order to locate the micro-earthquakes recorded by the OBS/H only a single station location technique was implemented and applied. Some multiplets have clouds of hypocenters overlapping each other. These clusters, indistinguishable without the application of a waveforms clustering technique, show differences in the waveforms that must be attributed to differences in focal mechanisms which generated the waveforms.

Estimation of velocity structure around a natural gas reservoir at Yufutsu, Japan, by microtremor survey

NASA Astrophysics Data System (ADS)

Shiraishi, H.; Asanuma, H.; Tezuka, K.

2010-12-01

Seismic reflection survey has been commonly used for exploration and time-lapse monitoring of oil/gas resources. Seismic reflection images typically have reasonable reliability and resolution for commercial production. However, cost consideration sometimes avoids deployment of widely distributed array or repeating survey in cases of time lapse monitoring or exploration of small-scale reservoir. Hence, technologies to estimate structures and physical properties around the reservoir with limited cost would be effectively used. Microtremor survey method (MSM) has an ability to realize long-term monitoring of reservoir with low cost, because this technique has a passive nature and minimum numbers of the monitoring station is four. MSM has been mainly used for earthquake disaster prevention, because velocity structure of S-wave is directly estimated from velocity dispersion of the Rayleigh wave. The authors experimentally investigated feasibility of the MSM survey for exploration of oil/gas reservoir. The field measurement was carried out around natural gas reservoir at Yufutsu, Hokkaido, Japan. Four types of arrays with array radii of 30m, 100m, 300m and 600m are deployed in each area. Dispersion curves of the velocity of Rayleigh wave were estimated from observed microtremors, and S-wave velocity structures were estimated by an inverse analysis of the dispersion curves with genetic algorism (GA). The estimated velocity structures showed good consistency with one dimensional velocity structure by previous reflection surveys up to 4-5 km. We also found from the field experiment that a data of 40min is effective to estimate the velocity structure even the seismometers are deployed along roads with heavy traffic.

Loss of stearoyl-CoA desaturase 1 rescues cardiac function in obese leptin-deficient mice.

PubMed

Dobrzyn, Pawel; Dobrzyn, Agnieszka; Miyazaki, Makoto; Ntambi, James M

2010-08-01

The heart of leptin-deficient ob/ob mice is characterized by pathologic left ventricular hypertrophy along with elevated triglyceride (TG) content, increased stearoyl-CoA desaturase (SCD) activity, and increased myocyte apoptosis. In the present study, using an ob/ob;SCD1(-/-) mouse model, we tested the hypothesis that lack of SCD1 could improve steatosis and left ventricle (LV) function in leptin deficiency. We show that disruption of the SCD1 gene improves cardiac function in ob/ob mice by correcting systolic and diastolic dysfunction without affecting levels of plasma TG and FFA. The improvement is associated with reduced expression of genes involved in FA transport and lipid synthesis in the heart, as well as reduction in cardiac FFA, diacylglycerol, TG, and ceramide levels. The rate of FA beta-oxidation is also significantly lower in the heart of ob/ob;SCD1(-/-) mice compared with ob/ob controls. Moreover, SCD1 deficiency reduces cardiac apoptosis in ob/ob mice due to increased expression of antiapoptotic factor Bcl-2 and inhibition of inducible nitric oxide synthase and caspase-3 activities. Reduction in myocardial lipid accumulation and inhibition of apoptosis appear to be one of the main mechanisms responsible for improved LV function in ob/ob mice caused by SCD1 deficiency.

Novel regulatory mechanisms for generation of the soluble leptin receptor: implications for leptin action.

PubMed

Schaab, Michael; Kausch, Henriette; Klammt, Juergen; Nowicki, Marcin; Anderegg, Ulf; Gebhardt, Rolf; Rose-John, Stefan; Scheller, Juergen; Thiery, Joachim; Kratzsch, Juergen

2012-01-01

The adipokine leptin realizes signal transduction via four different membrane-anchored leptin receptor (Ob-R) isoforms in humans. However, the amount of functionally active Ob-R is affected by constitutive shedding of the extracellular domain via a so far unknown mechanism. The product of the cleavage process the so-called soluble leptin receptor (sOb-R) is the main binding protein for leptin in human blood and modulates its bioavailability. sOb-R levels are differentially regulated in metabolic disorders like type 1 diabetes mellitus or obesity and can, therefore, enhance or reduce leptin sensitivity. To describe mechanisms of Ob-R cleavage and to investigate the functional significance of differential sOb-R levels we established a model of HEK293 cells transiently transfected with different human Ob-R isoforms. Using siRNA knockdown experiments we identified ADAM10 (A Disintegrin And Metalloproteinase 10) as a major protease for constitutive and activated Ob-R cleavage. Additionally, the induction of lipotoxicity and apoptosis led to enhanced shedding shown by increased levels of the soluble leptin receptor (sOb-R) in cell supernatants. Conversely, high leptin concentrations and ER stress reduced sOb-R levels. Decreased amounts of sOb-R due to ER stress were accompanied by impaired leptin signaling and reduced leptin binding. Lipotoxicity and apoptosis increased Ob-R cleavage via ADAM10-dependent mechanisms. In contrast high leptin levels and ER stress led to reduced sOb-R levels. While increased sOb-R concentrations seem to directly block leptin action, reduced amounts of sOb-R may reflect decreased membrane expression of Ob-R. These findings could explain changes of leptin sensitivity which are associated with variations of serum sOb-R levels in metabolic diseases.

Novel Regulatory Mechanisms for Generation of the Soluble Leptin Receptor: Implications for Leptin Action

PubMed Central

Schaab, Michael; Kausch, Henriette; Klammt, Juergen; Nowicki, Marcin; Anderegg, Ulf; Gebhardt, Rolf; Rose-John, Stefan; Scheller, Juergen; Thiery, Joachim; Kratzsch, Juergen

2012-01-01

Background The adipokine leptin realizes signal transduction via four different membrane-anchored leptin receptor (Ob-R) isoforms in humans. However, the amount of functionally active Ob-R is affected by constitutive shedding of the extracellular domain via a so far unknown mechanism. The product of the cleavage process the so-called soluble leptin receptor (sOb-R) is the main binding protein for leptin in human blood and modulates its bioavailability. sOb-R levels are differentially regulated in metabolic disorders like type 1 diabetes mellitus or obesity and can, therefore, enhance or reduce leptin sensitivity. Methodology/Principal Findings To describe mechanisms of Ob-R cleavage and to investigate the functional significance of differential sOb-R levels we established a model of HEK293 cells transiently transfected with different human Ob-R isoforms. Using siRNA knockdown experiments we identified ADAM10 (A Disintegrin And Metalloproteinase 10) as a major protease for constitutive and activated Ob-R cleavage. Additionally, the induction of lipotoxicity and apoptosis led to enhanced shedding shown by increased levels of the soluble leptin receptor (sOb-R) in cell supernatants. Conversely, high leptin concentrations and ER stress reduced sOb-R levels. Decreased amounts of sOb-R due to ER stress were accompanied by impaired leptin signaling and reduced leptin binding. Conclusions Lipotoxicity and apoptosis increased Ob-R cleavage via ADAM10-dependent mechanisms. In contrast high leptin levels and ER stress led to reduced sOb-R levels. While increased sOb-R concentrations seem to directly block leptin action, reduced amounts of sOb-R may reflect decreased membrane expression of Ob-R. These findings could explain changes of leptin sensitivity which are associated with variations of serum sOb-R levels in metabolic diseases. PMID:22545089

A complete tomography of the Earth's interior with floating seismometers in the oceans: the EarthScope-Oceans

NASA Astrophysics Data System (ADS)

Chen, Y. J.; Nolet, G.

2016-12-01

While the tomography techniques of imaging the earth's interior have been improved significantly over the past three decades the resolution of the resulting 3D images of the earth's interior, particularly the lower mantle, has been severely limited by the lack of seismic stations in the oceans which cover the 2/3 of the earth's surface. But this is going to be changed by the recently developed floating hydrophones called "Mermaids" which, freely floating under the sea surface, can operate as seismometers (see abstract by Nolet et al. in session DI010). These `Mermaids' have recorded (1) teleseismic waves, crucial to provide resolution for tomographic images of the deep mantle beneath oceanic areas, as well as (2) swarms of earthquakes too small to be observed on land, indicative of tectonic motions on oceanic ridges. Transmission is in quasi-real time by satellite (Iridium). A new version of the Mermaid, of much larger capacity, with a lifetime of five to six years is available for deployment. SUSTC in Shenzhen, China, in close collaboration with Geoazur (France), will launch the first stage of a large scale, global network of floating seismometers in the oceans named EarthScope-Oceans in 2017 by setting afloat 50 Mermaids in the Indian Ocean. Japan and other European nations may join the effort, which should reach 500 sensors by 2019 covering the entire world oceans. After that, the robots will be equipped with sophisticated software currently under development, which adds the capacity to juggle up to eight sensors and that has a reprogramming ability even during missions. We then expect the network to become multi-disciplinary and be able to host instruments not only for global seismology but also for biologists, oceanographers, geochemists, meteorologists and others. This new monitoring network will greatly improve our knowledge of acoustic noise pollution, of cetacean populations and their interaction with noise and meteorological conditions in all of the oceans by providing large and continuous data coverage. It will transform the discipline of seismic tomography at sea and improve our understanding of geodynamical processes operating in the deep mantle of the Earth by filling the data gap that currently exists in the oceanic domain.

Constructing new seismograms from old earthquakes: Retrospective seismology at multiple length scales

NASA Astrophysics Data System (ADS)

Entwistle, Elizabeth; Curtis, Andrew; Galetti, Erica; Baptie, Brian; Meles, Giovanni

2015-04-01

If energy emitted by a seismic source such as an earthquake is recorded on a suitable backbone array of seismometers, source-receiver interferometry (SRI) is a method that allows those recordings to be projected to the location of another target seismometer, providing an estimate of the seismogram that would have been recorded at that location. Since the other seismometer may not have been deployed at the time the source occurred, this renders possible the concept of 'retrospective seismology' whereby the installation of a sensor at one period of time allows the construction of virtual seismograms as though that sensor had been active before or after its period of installation. Using the benefit of hindsight of earthquake location or magnitude estimates, SRI can establish new measurement capabilities closer to earthquake epicenters, thus potentially improving earthquake location estimates. Recently we showed that virtual SRI seismograms can be constructed on target sensors in both industrial seismic and earthquake seismology settings, using both active seismic sources and ambient seismic noise to construct SRI propagators, and on length scales ranging over 5 orders of magnitude from ~40 m to ~2500 km[1]. Here we present the results from earthquake seismology by comparing virtual earthquake seismograms constructed at target sensors by SRI to those actually recorded on the same sensors. We show that spatial integrations required by interferometric theory can be calculated over irregular receiver arrays by embedding these arrays within 2D spatial Voronoi cells, thus improving spatial interpolation and interferometric results. The results of SRI are significantly improved by restricting the backbone receiver array to include approximately those receivers that provide a stationary phase contribution to the interferometric integrals. We apply both correlation-correlation and correlation-convolution SRI, and show that the latter constructs virtual seismograms with fewer non-physical arrivals. Finally we reconstruct earthquake seismograms at sensors that were previously active but were subsequently removed before the earthquakes occurred; thus we create virtual earthquake seismograms at those sensors, truly retrospectively. Such SRI seismograms can be used to create a catalogue of new, virtual earthquake seismograms that are available to complement real earthquake data in future earthquake seismology studies. [1]E. Entwistle, Curtis, A., Galetti, E., Baptie, B., Meles, G., Constructing new seismograms from old earthquakes: Retrospective seismology at multiple length scales, JGR, in press.

Five years on: Revisiting GSN data quality

NASA Astrophysics Data System (ADS)

Gee, L. S.; Nettles, M.; Ekstrom, G.; Davis, J. P.; Ringler, A. T.; Storm, T. L.; Wilson, D.; Anderson, K. R.

2014-12-01

In 2010, the Lamont Waveform Quality Center (WQC) conducted an in-depth review of ten stations in the Global Seismographic Network (GSN). IU stations (CASY, DAV, KIP, KONO, WCI), IC stations (SSE, XAN), and II stations (ALE, DGAR, RPN) were analyzed using a scaling analysis based on data-synthetic comparisons, evaluation of noise levels, assessment of inter-sensor coherence, and polarization analysis. These reports (available from http://www.ldeo.columbia.edu/~ekstrom/Projects/WQC.html) highlighted a number of significant problems in GSN data quality, including the frequency-dependent loss of gain in the STS-1 seismometer (Ekström et al., 2006) that has been attributed to the presence of humidity in the electronics, cables, and connectors (Yuki and Ishihara, 2002; Hutt and Ringler, 2011). The reports from the WQC spurred a number of changes in the operation of the GSN, including the adoption of the policy of annual calibrations and the development of new tools and metrics to monitor, evaluate, and communicate data quality. In parallel, the USGS' Albuquerque Seismological Laboratory (ASL) and UCSD's Project IDA worked with the IRIS Consortium to upgrade GSN stations with new data acquisition systems, to refurbish the STS-1 seismometers with new electronics, and to expand the deployment of secondary broadband sensors. We revisit the 2010 reports, using the tools of the WQC as well as a number of newly developed tools such as the USGS' Data Quality Analyzer and IRIS' MUSTANG, and provide an update on GSN data quality. Our initial focus is on CASY and KIP, the first two stations reviewed by the WQC. Our goal is to evaluate progress in the last five years and assess our ability to quantify data quality as well as to identify potential problems that could compromise data quality in the future. Ekström, G., C. A. Dalton, and M. Nettles (2006). Observations of time-dependent errors in long-period instrument gain at global seismic stations. Seismological Research Letters, 77 (1), 12-22. Hutt, C.R. and A.T. Ringler (2011). Some possible causes of and corrections for STS-1 response changes in the Global Seismographic Network, Seis. Res. Lett., 82 (4), 560-571. Yuki, Y., and Y. Ishihara (2002). Methods for maintaining the performance of STS-1 seismometer. Frontier Research on Earth Evolution 2, 1-5.

Seismic investigation on the Littoral Faults Zone in the northern continental margin of South China Sea

NASA Astrophysics Data System (ADS)

Sun, J.; Xu, H.; Xia, S.; Cao, J.; Wan, K.

2017-12-01

The continental margin of the northern South China Sea (SCS) had experienced continuous evolution from an active continental margin in the late Mesozoic to a passive continental margin in the Cenozoic. The 1200km-long Littoral Faults Zone (LFZ) off the mainland South China was suggested to represent one of the sub-plate boundaries and play a key role during the evolution. Besides, four devastating earthquakes with magnitude over 7 and another 11 destructive events with M>6 were documented to have occurred along the LFZ. However, its approximity to the shoreline, the shallow water depth, and the heavy fishing activities make it hard to conduct a marine seismic investigation. As a result, understandings about the LFZ before 2000 were relatively poor and mostly descriptive. After two experiments of joint onshore-offshore wide-angle seismic surveys in the 1st decade of this century, several cruses aiming to unveil the deep structure of the LFZ were performed in the past few years, with five joint onshore-offshore wide-angle seismic survey profiles completed. Each of these profiles is perpendicular to the shoreline, with four to five seismometers of campaign mode deployed on the landside and over ten Ocean Bottom Seismometers (OBSs) spacing at 20km deployed on the seaside. Meanwhile, multi-channel seismic (MCS) data along these profiles were obtained simultaneously. Based on these data, velocity models from both forward modeling and inversion were obtained. According to these models, the LFZ was imaged to be a low-velocity fractured zone dipping to the SSE-SE at a high-angle and cutting through the thinned continental crust at some locations. Width of the fractured zone varies from 6km to more than 10km from site to site. With these results, it is suggested that the LFZ accommodates the stresses from both the east side, where the Eurasia/Philippine Sea plate converging and mountain building is ongoing, and the west side, where a strike-slip between the Indochina peninsular and the South China is occurring. Moreover, a low-velocity layer on the top of the lower-crust was also modeled, and its intersection with the fractured zone formed a weak zone where stresses concentrated, and led to those abovementioned earthquakes along the LFZ.

The 2014 Greeley, Colorado Earthquakes: Science, Industry, Regulation, and Media

NASA Astrophysics Data System (ADS)

Yeck, W. L.; Sheehan, A. F.; Weingarten, M.; Nakai, J.; Ge, S.

2014-12-01

On June 1, 2014 (UTC) a magnitude 3.2 earthquake occurred east of the town of Greeley, Colorado. The earthquake was widely felt, with reports from Boulder and Golden, over 60 miles away from the epicenter. The location of the earthquake in a region long considered aseismic but now the locus of active oil and gas production prompted the question of whether this was a natural or induced earthquake. Several classic induced seismicity cases hail from Colorado, including the Rocky Mountain Arsenal earthquakes in the 1960s and the Paradox Valley earthquakes in western Colorado. In both cases the earthquakes were linked to wastewater injection. The Greeley earthquake epicenter was close to a Class II well that had been injecting waste fluid into the deepest sedimentary formation of the Denver Basin at rates as high as 350,000 barrels/month for less than a year. The closest seismometers to the June 1 event were more than 100 km away, necessitating deployment of a local seismic network for detailed study. IRIS provided six seismometers to the University of Colorado which were deployed starting within 3 days of the mainshock. Telemetry at one site allowed for real time monitoring of the ongoing seismic sequence. Local media interest was extremely high with speculation that the earthquake was linked to the oil and gas industry. The timetable of media demand for information provided some challenges given the time needed for data collection and analysis. We adopted a policy of open data and open communication with all interested parties, and made proactive attempts to provide information to industry and regulators. After 3 weeks of data collection and analysis, the proximity and timing of the mainshock and aftershocks to the C4A injection well, along with a sharp increase in seismicity culminating in an M 2.6 aftershock, led to a decision by the Colorado Oil and Gas Corporation Commission (COGCC) to recommend a temporary halt to injection at the C4A injection well. This was the first time that such action had been taken by the COGCC. This presentation provides an overview of the interactions among academic researchers, industry, media, and regulators during the period of rapid response to this earthquake sequence, and the role of seismology in informing those responses.

Leptin and leptin receptor are detectable in equine spermatozoa but are not involved in in vitro fertilisation.

PubMed

Lange-Consiglio, Anna; Corradetti, Bruna; Perrini, Claudia; Bizzaro, Davide; Cremonesi, Fausto

2016-04-01

In human and swine, leptin (OB) has been identified in seminal plasma and leptin receptors (OB-R) on the cell surface of spermatozoa, indicating that spermatozoa are a target for OB. This hormone has also been detected in follicular fluid (FF) in women and mares, although its role requires further study. The aims of this study were to investigate the immunolocalisation and the expression of OB and OB-R in equine spermatozoa and to evaluate the involvement of OB in equine in vitro fertilisation (IVF). Since progesterone (P) and OB are both found in FF, the individual and combined effects of these two hormones were studied in equine IVF and compared with the results obtained from the use of FF for in vitro sperm preparation. For the first time, we were able to identify OB and OB-R mRNA and their corresponding proteins in equine spermatozoa. When spermatozoa were treated with OB, there was a decrease in the three motility parameters VSL, STR and LIN, commonly associated with hyperactivation, whilst the acrosome reaction rate increased (P<0.05). The fertilisation rate was 51% with FF, 46.15% with P, 43.64% with P+OB and 0% with OB alone. The percentage of eight-cell stage embryos was 18.7% with FF, 17.1% with P and 16.7% with OB+P. OB alone did not permit oocyte fertilisation, indicating that, in the horse, OB is involved in capacitation and hyperactivation but not in sperm penetration.

Map, Excite, Jump, and Measure: An Outreach Activity That Utilizes Seismology to Engage Students in Technology, Science, Engineering, and Mathematics

NASA Astrophysics Data System (ADS)

van der Lee, S.; Tekverk, K.; Rooney, K.; Boxerman, J.

2013-12-01

We designed and will present a lesson plan to teach students STEM concepts through seismology. The plan addresses new generation science standards in the Framework for K-12 Science Education as well AAAS Benchmarks for Science Literacy. The plan can be executed at a facility with a seismometer in a research facility or university, on a field trip, but it can also be used in a school setting with a school seismometer. Within the lesson plan, the students first use technology to obtain earthquake location data and map them. Next, the students learn about the science of earthquakes, which is followed by an engineering activity in which the students design a hypothetical seismometer and interact with the actual seismometer and live data display. Lastly the students use mathematics to locate an earthquake through trilateration. The lesson plan has been fine-tuned through implementation with over 150 students from grades 3-12 from the Chicago area.

Review of the Usefulness of Various Rotational Seismometers with Laboratory Results of Fibre-Optic Ones Tested for Engineering Applications

PubMed Central

Jaroszewicz, Leszek R.; Kurzych, Anna; Krajewski, Zbigniew; Marć, Paweł; Kowalski, Jerzy K.; Bobra, Piotr; Zembaty, Zbigniew; Sakowicz, Bartosz; Jankowski, Robert

2016-01-01

Starting with descriptions of rotational seismology, areas of interest and historical field measurements, the fundamental requirements for rotational seismometers for seismological and engineering application are formulated. On the above basis, a review of all existing rotational seismometers is presented with a description of the principles of their operation as well as possibilities to fulfill formulated requirements. This review includes mechanical, acoustical, electrochemical and optical devices and shows that the last of these types are the most promising. It is shown that optical rotational seismometer based on the ring-laser gyroscope concept is the best for seismological applications, whereas systems based on fiber-optic gyroscopes demonstrate parameters which are also required for engineering applications. Laboratory results of the Fibre-Optic System for Rotational Events & Phenomena Monitoring using a small 1-D shaking table modified to generate rotational excitations are presented. The harmonic and time-history tests demonstrate its usefulness for recording rotational motions with rates up to 0.25 rad/s. PMID:27999299

Evidence for an interaction between leptin, T cell costimulatory antigens CD28, CTLA-4 and CD26 (dipeptidyl peptidase IV) in BCG-induced immune responses of leptin- and leptin receptor-deficient mice.

PubMed

Rüter, Jens; Hoffmann, Torsten; Demuth, Hans-Ulrich; Moschansky, Petra; Klapp, Burghard F; Hildebrandt, Martin

2004-06-01

We assessed changes of the enzyme dipeptidyl peptidase IV (DPP IV, CD26) in the context of leptin or leptin receptor deficiency. C57BL/6 mice, Leptin-deficient mice (ob/ob mice, B6.V-Lep) and Leptin-receptor-deficient mice (db/db mice, B6.Cg-m+/+Lepr) were infected with B. Calmette-Guerin (BCG) and sacrificed three days later. DPP IV activity in serum was higher in ob/ob mice and in db/db mice than in wild-type mice. The expression of DPP IV/CD26 on splenocytes was higher in ob/ob mice than in wild-type animals, and lower in db/db mice, and decreased upon stimulation with BCG in ob/ob mice only. Several T cell antigens including CTLA-4 were expressed aberrantly in ob/ob and in db/db mice. Our observations provide evidence for a relationship between DPP IV and leptin.

Effects of ovarian steroids and prolactin on the sequential development of nesting behaviour in female budgerigars.

PubMed

Hutchison, R E

1975-10-01

As intact, breeding female budgerigars approach egg-laying, they spend an increasing amount of time in the nestbox and nest hollow. The brood patch area begins to defeather and becomes vascular and the oviduct increases in weight. Precursory albumen forms in the tubular glands of the oviduct. Oestradiol (OB) treatment in combination with prolactin (OB+PL) induced ovariectomized budgerigars to display nesting behaviour which did not differ from that shown by intact females in the 3 days immediately preceding egg-laying. In contrast, OB induced only the initial phase of the nesting sequence and the effects of OB in combination with progesterone (OB+PR) were intermediate between treatments with OB alone and OB+PL. Incubation of artificial eggs occurred only in the OB+PL group and the latency to display of the incubation posture was shorter in the OB+PL group than in the OB+PR group. No incubation posture was displayed by the OB-treated group. Oviduct development was not influenced by prolactin, but progesterone induced precocious development of tubular glands in the magnum region of the oviduct. Treatment with OB+PR induced uniform development of precursor albumen in the tubular glands. Development of the brood patch occurred with both OB+PL and OB+PR treatment. However, OB+PR resulted in defeathering which was advanced in relation to vascularity when compared with intact breeding females, whereas defeathering and vascularity of the OB+PL group did not differ from that of intact females at egg-laying. These results indicate that prolactin in combination with oestradiol was more effective than progesterone not only in inducing the later phases of nesting behaviour but also in initiating incubation behaviour and defeathering of the brood patch area.

Interleukin-18, together with interleukin-12, induces severe acute pancreatitis in obese but not in nonobese leptin-deficient mice

PubMed Central

Sennello, Joseph A.; Fayad, Raja; Pini, Maria; Gove, Melissa E.; Ponemone, Venkatesh; Cabay, Robert J.; Siegmund, Britta; Dinarello, Charles A.; Fantuzzi, Giamila

2008-01-01

Obesity is associated with increased severity of acute pancreatitis (AP). The cytokines IL-18 and IL-12 are elevated in patients with AP, and IL-18 levels are high in obesity. We aimed to develop a pathologically relevant model to study obesity-associated severe AP. Lean WT and obese leptin-deficient ob/ob mice received two injections of IL-12 plus IL-18. Survival, pancreatic inflammation, and biochemical markers of AP were measured. Dosing with IL-12 plus IL-18 induced 100% lethality in ob/ob mice; no lethality was observed in WT mice. Disruption of pancreatic exocrine tissue and acinar cell death as well as serum amylase and lipase levels were significantly higher in ob/ob than in WT mice. Edematous AP developed in WT mice, whereas obese ob/ob mice developed necrotizing AP. Adipose tissue necrosis and saponification were present in cytokine-injected ob/ob but not in WT mice. Severe hypocalcemia and elevated acute-phase response developed in ob/ob mice. The cytokine combination induced high levels of regenerating protein 1 and pancreatitis-associated protein expression in the pancreas of WT but not of ob/ob mice. To differentiate the contribution of obesity to that of leptin deficiency, mice received short- and long-term leptin replacement therapy. Short-term leptin reconstitution in the absence of major weight loss did not protect ob/ob mice, whereas leptin deficiency in the absence of obesity resulted in a significant reduction in the severity of the pancreatitis. In conclusion, we developed a pathologically relevant model of AP in which obesity per se is associated with increased severity. PMID:18515422

Object-based connectedness facilitates matching.

PubMed

Koning, Arno; van Lier, Rob

2003-10-01

In two matching tasks, participants had to match two images of object pairs. Image-based (IB) connectedness refers to connectedness between the objects in an image. Object-based (OB) connectedness refers to connectedness between the interpreted objects. In Experiment 1, a monocular depth cue (shadow) was used to distinguish different relation types between object pairs. Three relation types were created: IB/OB-connected objects, IB/OB-disconnected objects, and IB-connected/OB-disconnected objects. It was found that IB/OB-connected objects were matched faster than IB/OB-disconnected objects. Objects that were IB-connected/OB-disconnected were matched equally to IB/OB-disconnected objects. In Experiment 2, stereoscopic presentation was used. With relation types comparable to those in Experiment 1, it was again found that OB connectedness determined speed of matching, rather than IB connectedness. We conclude that matching of projections of three-dimensional objects depends more on OB connectedness than on IB connectedness.

Seismicity and geodynamics in the central part of the Vanuatu Arc

NASA Astrophysics Data System (ADS)

Baillard, C.; Crawford, W. C.; Ballu, V.; Regnier, M. M.; Pelletier, B.; Garaebiti, E.

2013-12-01

The Vanuatu Arc (VA) in the southwest Pacific ocean (167°E, 13-20°S), is highly seismically active, with more than 35 events of magnitude Mw ≥ 7 since 1973 (USGS catalog). The geodynamics are dominated by the east-dipping subduction of the Australian Plate under the North Fiji Basin microplate. Convergence rates are estimated to be between 130 and 170 mm/yr, except in the central part of the VA where convergence slows to 30-40 mm/yr. This slowing appears to be the result of blockage by the subducting d'Entrecastaux ridge. To quantify the tectonics of this blocked section, we deployed 30 seismometers in 2008-2009 and 8 GPS stations since 2008, in the forearc region of the central VA. The seismometers recorded more than 100 events/day. Detailed analysis of the earthquake catalog reveals: 1) a seismic gap between 40 and 60 km deep under the two largest islands of the VA (Santo and Malekula); 2) subduction plane and intraplate faulting within the down-going plate; and 3) reduced activity beneath Malekula island , perhaps indicating a locked patch on the subduction plane. We infer the geometry of the subduction interface by combining our catalog with unpublished data from the 2000 Santo Mw 6.9 earthquake and aftershocks and the USGS and Global CMT catalogs. The subduction interface appears to be composed of two different panels: a shallow one with a small dip angle and a deeper one with higher dip starting at a depth of ~50 km. We compare finite-element modeling of these panels to the geodetic data to test the connectedness of the two panels and their degree of locking.

Data Release Report for Source Physics Experiments 2 and 3 (SPE-2 and SPE-3) Nevada National Security Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Townsend, Margaret; Obi, Curtis

2015-04-30

The second Source Physics Experiment shot (SPE-2) was conducted in Nevada on October 25, 2011, at 1900:00.011623 Greenwich Mean Time (GMT). The explosive source was 997 kilograms (kg) trinitrotoluene (TNT) equivalent of sensitized heavy ammonium fuel oil (SHANFO) detonated at a depth of 45.7 meters (m). The third Source Physics Experiment shot (SPE-3) was conducted in Nevada on July 24, 2012, at 1800:00.44835 GMT. The explosive source was 905 kg TNT equivalent of SHANFO detonated at a depth of 45.8 m. Both shots were recorded by an extensive set of instrumentation that includes sensors both at near-field (less than 100more » m) and far-field (100 m or greater) distances. The near-field instruments consisted of three-component accelerometers deployed in boreholes at 15, 46, and 55 m depths around the shot and a set of single-component vertical accelerometers on the surface. The far-field network was composed of a variety of seismic and acoustic sensors, including short-period geophones, broadband seismometers, three-component accelerometers, and rotational seismometers at distances of 100 m to 25 kilometers. This report coincides with the release of these data for analysts and organizations that are not participants in this program. This report describes the second and third Source Physics Experiment shots and the various types of near-field and farfield data that are available.This revised document includes reports on baseline shift corrections for the SPE-2 and SPE-3 shots that were missing from the original January 2015 version.« less

Seismicity and tectonic tremor accompany the 2014 Gisborne Slow Slip Event: Insights from the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS) Experiment, New Zealand

NASA Astrophysics Data System (ADS)

Todd, E. K.; Schwartz, S. Y.; Sheehan, A. F.; Mochizuki, K.

2016-12-01

The northern Hikurangi Margin is host to some of the shallowest slow slip events (SSEs) in the world. Slow slip offshore Gisborne, New Zealand has been observed at depths as shallow as 2 km and may extend all the way to the trench. Gisborne SSEs are accompanied by tectonic tremor and increased levels of seismicity, but this activity has only been observed at the onshore, downdip edge of the slow slip patch. Between May 2014 and June 2015, 24 absolute pressure gauges, 10 broadband seismometers, and 5 short period seismometers were deployed offshore Gisborne along the east coast of the North Island of New Zealand as part of the HOBITSS Experiment. These instruments were in place during a large Gisborne SSE (peak slip 20 cm) in September and October 2014. Using this new ocean-derived dataset in conjunction with existing land data from the New Zealand National Seismograph Network operated by GeoNet (http://geonet.org.nz), we present an in-depth, systematic investigation of tremor and microseismicity associated with this shallow Gisborne SSE to further examine the spatial heterogeneity of slip processes on the shallow megathrust. Tremor and earthquakes are collocated with the geodetically inverted slow slip patch with tremor occurring offshore and earthquakes concentrated downdip of a shallowly subducted seamount near the region of peak displacement during the SSE. This discovery indicates that the region of the megathrust slipping in these SSEs is capable of multiple types of slip and understanding the spatiotemporal relationships between these strain release modes has implications for local seismic hazards.

Offshore seismicity at Hikurangi Margin from Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS), New Zealand

NASA Astrophysics Data System (ADS)

Yarce, J.; Sheehan, A. F.; Nakai, J. S.; Todd, E. K.; Schwartz, S. Y.; Mochizuki, K.

2016-12-01

The Hikurangi margin off the north island of New Zealand is the target of the "Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip" (HOBITSS) experiment, which successfully recorded a slow slip event in 2014. In the HOBITSS experiment 10 broadband and 5 short period ocean bottom seismometers along with 24 absolute pressure gauges where deployed for one year (May 2014 to June 2015) offshore the east coast of the North Island of New Zealand, near Gisborne. A catalog of local earthquakes is being constructed using STA/LTA detection, event association, and manual picking of P and S wave arrivals from both HOBITSS and GeoNet data. Our examination of initial hypocenters from the first 10 weeks of data yields 849 local earthquakes with a concentration of epicenters offshore over the forearc basin and deformed accretionary wedge. A bimodal distribution of hypocenter depths is identified with peaks at 10 and 35 km. Deeper events (between 50 and 80 km) are found to the west of our seismometer array, presumably on the interface of the subducted Pacific plate beneath the Australian plate. On the eastern edge of the array, on the incoming Pacific plate, seismicity is scarce with shallow hypocenters. For the one-year period, GEONET reports 2109 earthquakes, while our 15 weeks of manual picking has resulted in 1400 events, which suggests an increase of detections of a factor of 2-3 due to the offshore array. Epicentral location and depth results will be explored using different location algorithms such as Bayesloc and Nonlinloc with regionally appropriate local velocity models. The results presented here will be combined with others to build a more complete picture of the relationship between fast (earthquake) and slow slip.

Microseismic Properties of Typhoons in the Western Pacific

NASA Astrophysics Data System (ADS)

Xu, Y.; Koper, K. D.; Burlacu, R.

2017-12-01

We analyzed the ambient seismic noise recorded in 2012 by a temporary array of 240 seismometers deployed in Yunnan, China as part of Phase I of the ChinArray project. The stations were installed with a quasi-uniform spacing of about 70 km by the Yunnan Earthquake Administration. Each station consisted of a three-component Guralp-3ESP seismometer and a Reftek 130 data acquisition system with a sampling interval of 0.01 s. To identify the structure and source of the ambient noise, we applied frequency-dependent polarization analysis to the individual stations and f-k analysis for three sub-arrays consisting of 14-25 stations. The most prominent microseismic signals we observed were surface waves generated at periods of 3-7 s by 15 typhoons that occurred in the Western Pacific, mostly during the summer of 2012. The U.S. Navy's Joint Typhoon Warning Center divides a tropical cyclone into four levels, Tropical Depression (TD), Tropical Storm (TS), Typhoon (TY) and Super Typhoon (ST) based on the estimated wind speed. Four of the 15 analyzed typhoons reached ST intensity. The maximum microseism signals tended to last throughout the lifetime of a typhoon. Sometimes, we observed the splitting of a single microseism spectral peak into two parallel peaks. We compared the seismic observations to storm track data for typhoons Guchol, Jelawat, and Son-Tinh, and with oceanic models of wave-wave interaction. We find that microseismic power is correlated with changes in the direction or speed, or both, of the typhoon track. High wind speed or changing wind speed within the typhoon does not have a clear relationship with the microseismic power.

Site Assessment of a New State-Wide Seismic Network in Texas (TexNet)

NASA Astrophysics Data System (ADS)

Savvaidis, A.; Young, B.; Mukherjee, T.; Hennings, P.; Rathje, E.; Zalachoris, G.; Young, M.; Walter, J. I.; DeShon, H. R.; Frohlich, C.

2016-12-01

Earthquake activity has recently increased in the southern mid-continent of the U.S., including Texas. To monitor seismicity activity in the state of Texas, a new seismicity monitoring program known as TexNet, was funded by the Texas State Legislature in 2015. TexNet consists of 22 new permanent broadband (120s post-hole) seismic stations that will complement the 17 stations currently operating in the State. These permanent stations will provide the baseline seismicity of the state. In addition, 36 portable stations (incorporating both a 20s post-hole seismometer and a post-hole accelerometer) will be used to densify the network in specific areas, of the State, depending on measured seismicity level, proximity to infrastructure, or other scientific investigations. One goal for TexNet is to provide authenticated data needed to evaluate the location, and frequency of earthquakes. To minimize the uncertainties in earthquake locations and increase detectability of the network, an extensive site assessment survey was conducted. The initial station positions were chosen based on Earthscope, Transportable Array (TA) site positions, while ensuring that the stations were relatively evenly-spaced across the State. We then analyzed the noise and earthquake data from the TA seismometers, and added new locations based on geology, topography, and absence of nearby human activities. A 30-min noise test was conducted at each site to identify the site amplification using HVSR information. A 24-hr survey then followed, where the noise level during day and night was identified, analyzed using power spectral density and compared to the NHNM and NLNM (Peterson, 1993; USGS Open File Report, 322). Based on these survey results nearby alternative sites were evaluated to improve final site position. Full deployment and data streaming is expected by December 2016, and will be discussed during this presentation.

Site Assessment of a New State-Wide Seismic Network in Texas (TexNet), USA.

NASA Astrophysics Data System (ADS)

Savvaidis, Alexandros; Young, Bissett; Hennings, Peter; Rathje, Ellen; Zalachoris, George; Young, Michael H.; Walter, Jacob I.; DeShon, Heather R.; Frohlich, Cliff

2017-04-01

Earthquake activity has recently increased in the southern mid-continent of the U.S., including Texas. To monitor seismicity activity in the state of Texas, a new seismicity monitoring program known as TexNet, was funded by the Texas State Legislature in 2015. TexNet consists of 22 new permanent broadband (120s post-hole) seismic stations that will complement the 17 stations currently operating in the State. These permanent stations will provide the baseline seismicity of the state. In addition, 36 portable stations (incorporating both a 20s post-hole seismometer and a post-hole accelerometer) will be used to densify the network in specific areas, of the State, depending on measured seismicity level, proximity to infrastructure, or other scientific investigations. One goal for TexNet is to provide authenticated data needed to evaluate the location, and frequency of earthquakes. To minimize the uncertainties in earthquake locations and increase detectability of the network, an extensive site assessment survey was conducted. The initial station positions were chosen based on Earthscope, Transportable Array (TA) site positions, while ensuring that the stations were relatively evenly-spaced across the State. We then analyzed the noise and earthquake data from the TA seismometers, and added new locations based on geology, topography, and absence of nearby human activities. A 30-min noise test was conducted at each site to identify the site amplification using HVSR information. A 24-hr survey then followed, where the noise level during day and night was identified, analyzed using power spectral density and compared to the NHNM and NLNM (Peterson, 1993; USGS Open File Report, 322). Based on these survey results nearby alternative sites were evaluated to improve final site position. Deployment and data streaming started on September 2016, and will be discussed during this presentation.

Deficiency in Nrf2 transcription factor decreases adipose tissue mass and hepatic lipid accumulation in leptin-deficient mice.

PubMed

Xu, Jialin; Donepudi, Ajay C; More, Vijay R; Kulkarni, Supriya R; Li, Liya; Guo, Liangran; Yan, Bingfang; Chatterjee, Tapan; Weintraub, Neal; Slitt, Angela L

2015-02-01

To evaluate whether Nrf2 deficiency impacts insulin resistance and lipid accumulation in liver and white adipose tissue. Lep(ob/ob) mice (OB) with targeted Nrf2 deletion (OB-Nrf2KO) were generated. Pathogenesis of obesity and type 2 diabetes was measured in C57BL/6J, Nrf2KO, OB, and OB-Nrf2KO mice. Hepatic lipid content, lipid clearance, and very low-density lipoprotein (VLDL) secretion were determined between OB and OB-Nrf2KO mice. OB-Nrf2KO mice exhibited decreased white adipose tissue mass and decreased adipogenic and lipogenic gene expression compared with OB mice. Nrf2 deficiency prolonged hyperglycemia in response to glucose challenge, which was paralleled by reduced insulin-stimulated Akt phosphorylation. In OB mice, Nrf2 deficiency decreased hepatic lipid accumulation, decreased peroxisome proliferator-activated receptor γ expression and nicotinamide adenine dinucleotide phosphate (NADPH) content, and enhanced VLDL secretion. However, this observation was opposite in lean mice. Additionally, OB-Nrf2KO mice exhibited increased plasma triglyceride content, decreased HDL-cholesterol content, and enhanced apolipoprotein B expression, suggesting Nrf2 deficiency caused dyslipidemia in these mice. Nrf2 deficiency in Lep(ob/ob) mice reduced white adipose tissue mass and prevented hepatic lipid accumulation but induced insulin resistance and dyslipidemia. This study indicates a dual role of Nrf2 during metabolic dysregulation-increasing lipid accumulation in liver and white adipose tissue but preventing lipid accumulation in obese mice. © 2014 The Obesity Society.

Chromium (D-phenylalanine)3 improves obesity-induced cardiac contractile defect in ob/ob mice.

PubMed

Dong, Feng; Yang, Xiaoping; Sreejayan, Nair; Ren, Jun

2007-11-01

Low-molecular weight chromium compounds, such as chromium picolinate [Cr(pic)(3)], improve insulin sensitivity, although toxicity is a concern. We synthesized a novel chromium complex, chromium (d-phenylalanine)(3) [Cr(d-phe)(3)], in an attempt to improve insulin sensitivity with reduced toxicity. The aim of this study was to compare the two chromium compounds on cardiac contractile function in ob/ob obese mice. C57BL lean and ob/ob obese mice were randomly divided into three groups: H(2)O, Cr(d-phe)(3), or Cr(pic)(3) (45 mug/kg per day orally for 6 months). The glucose tolerance test displayed improved glucose clearance by Cr(d-phe)(3) but not Cr(pic)(3). Myocytes from ob/ob mice exhibited depressed peak shortening (PS) and maximal velocity of shortening/relengthening (+/-dL/dt), prolonged time-to-PS and time-to-90% relengthening (TR90), reduced electrically stimulated rise in intracellular Ca(2+) (Deltafura-2 fluorescence intensity), and slowed intracellular Ca(2+) decay. Although a 3-month Cr(d-phe)(3) treatment for a separate group of ob/ob and lean 2-month-old mice only rectified reduced +/-dL/dt in ob/ob mice, all mechanical and intracellular Ca(2+) abnormalities were significantly attenuated or ablated by 6 months of Cr(d-phe)(3) but not Cr(pic)(3) treatment (except TR90). Sarco(endo)plasmic reticulum Ca(2+) ATPase activity and Na(+)-Ca(2+) exchanger expression were depressed in ob/ob mice, which were reversed by both Cr(d-phe)(3) and Cr(pic)(3), with a more pronounced effect from Cr(d-phe)(3). Cr(d-phe)(3) corrected reduced insulin-stimulated glucose uptake and improved basal phosphorylation of Akt and insulin receptor, as well as insulin-stimulated phosphorylation of Akt and insulin receptor in ob/ob myocytes. Heart homogenates from ob/ob mice had enhanced oxidative stress and protein carbonyl formation compared with the lean group, which were attenuated by both Cr(d-phe)(3) and Cr(pic)(3). Our data suggest that the new Cr(d-phe)(3) compound possesses better cardio-protective and insulin-sensitizing properties against obesity.

Brain volume in early MS patients with and without IgG oligoclonal bands in CSF.

PubMed

Fenu, G; Lorefice, L; Sechi, V; Loi, L; Contu, F; Cabras, F; Coghe, G; Frau, J; Secci, M A; Melis, C; Schirru, L; Costa, G; Melas, V; Arru, M; Barracciu, M A; Marrosu, M G; Cocco, E

2018-01-01

Oligoclonal bands of IgG (OB) are proposed as an early prognostic factor of the disease. Growing attention is directed towards brain volume evaluation as a possible marker of the severity of MS. Previous studies found that MS patients lacking OB have less brain atrophy. to evaluate a possible relationship between OB and cerebral volume in a cohort of early MS patients. Inclusion criteria were: diagnosis of relapsing-remitting MS; CSF analysis and MRI acquired simultaneously and within 12 months from clinical onset. A total of 15 healthy controls underwent MRI. In 20 MS patients, CSF analysis did not show OB synthesis (OB negative group). A control group of 25 MS patients in whom OB was detected was also randomly recruited (OB positive group). T test showed a significant difference in NWV between the OB positive and OB negative groups (P value = 0.01), and between the OB positive group and the healthy controls (P value = 0.001). No differences were detected between OB negative group and healthy controls. Multivariable linear regression showed a relationship between NWV and OB synthesis (P value = 0.02) controlling for age, gender, and EDSS. Our preliminary results suggest that OB positive patients show more atrophy of white matter since early phases of the disease, supporting the role of CSF analysis as a prognostic factor in MS. Copyright © 2017 Elsevier B.V. All rights reserved.

Switching performance of OBS network model under prefetched real traffic

NASA Astrophysics Data System (ADS)

Huang, Zhenhua; Xu, Du; Lei, Wen

2005-11-01

Optical Burst Switching (OBS) [1] is now widely considered as an efficient switching technique in building the next generation optical Internet .So it's very important to precisely evaluate the performance of the OBS network model. The performance of the OBS network model is variable in different condition, but the most important thing is that how it works under real traffic load. In the traditional simulation models, uniform traffics are usually generated by simulation software to imitate the data source of the edge node in the OBS network model, and through which the performance of the OBS network is evaluated. Unfortunately, without being simulated by real traffic, the traditional simulation models have several problems and their results are doubtable. To deal with this problem, we present a new simulation model for analysis and performance evaluation of the OBS network, which uses prefetched IP traffic to be data source of the OBS network model. The prefetched IP traffic can be considered as real IP source of the OBS edge node and the OBS network model has the same clock rate with a real OBS system. So it's easy to conclude that this model is closer to the real OBS system than the traditional ones. The simulation results also indicate that this model is more accurate to evaluate the performance of the OBS network system and the results of this model are closer to the actual situation.

Holographic otoscope for nano-displacement measurements of surfaces under dynamic excitation

PubMed Central

Flores-Moreno, J. M.; Furlong, Cosme; Rosowski, John J.; Harrington, Ellery; Cheng, Jeffrey T.; Scarpino, C.; Santoyo, F. Mendoza

2011-01-01

Summary We describe a novel holographic otoscope system for measuring nano-displacements of objects subjected to dynamic excitation. Such measurements are necessary to quantify the mechanical deformation of surfaces in mechanics, acoustics, electronics, biology and many other fields. In particular, we are interested in measuring the sound-induced motion of biological samples, such as an eardrum. Our holographic otoscope system consists of laser illumination delivery (IS), optical head (OH), and image processing computer (IP) systems. The IS delivers the object beam (OB) and the reference beam (RB) to the OH. The backscattered light coming from the object illuminated by the OB interferes with the RB at the camera sensor plane to be digitally recorded as a hologram. The hologram is processed by the IP using Fresnel numerical reconstruction algorithm, where the focal plane can be selected freely. Our holographic otoscope system is currently deployed in a clinic, and is packaged in a custom design. It is mounted in a mechatronic positioning system to increase its maneuverability degrees to be conveniently positioned in front of the object to be measured. We present representative results highlighting the versatility of our system to measure deformations of complex elastic surfaces in the wavelength scale including a copper foil membrane and postmortem tympanic membrane (TM). PMID:21898459

Approaching hydrate and free gas distribution at the SUGAR-Site location in the Danube Delta

NASA Astrophysics Data System (ADS)

Bialas, Joerg; Dannowski, Anke; Zander, Timo; Klaeschen, Dirk; Klaucke, Ingo

2017-04-01

Gas hydrates did receive a lot of attention over the last decades when investigating their potential to serve as a possible source for Methane production. Among other world-wide programs the German SUGAR project sets out to investigate the entire chain from exploitation to production in Europe. Therefore research in the scope of the SUGAR project sets out to investigate a site in European EEZ for the detailed studies of hydrate and gas distribution in a permeable sediment matrix. Among others one aim of the project is to provide in situ samples of natural methane hydrate for further investigations by MEBO drilling. The Danube paleo-delta with its ancient canyon and levee systems was chosen as a possible candidate for hydrate formation within the available drilling range of 200 m below seafloor. In order to decide on the best drilling location cruise MSM34 (Bialas et al., 2014) of the German RV MARIA S MERIAN set out to acquire geophysical, geological and geochemical datasets for assessment of the hydrate content within the Danube paleo-delta, Black Sea. The Black Sea is well known for a significant gas content in the sedimentary column. Reports on observations of bottom simulating reflectors (BSR) by Popescu et al. (2007) and others indicate that free gas and hydrate occurrence can be expected within the ancient passive channel levee systems. A variety of inverted reflection events within the gas hydrate stability zone (GHSZ) were observed within the drilling range of MEBO and chosen for further investigation. Here we report on combined seismic investigations of high-resolution 2D & 3D multichannel seismic (MCS) acquisition accompanied by four component Ocean-Bottom-Seismometer (OBS) observations. P- and converted S-wave arrivals within the OBS datasets were analysed to provide overall velocity depth models. Due to the limited length of profiles the majority of OBS events are caused by near vertical reflections. While P-wave events have a significant lateral coverage, converted S-waves do image a much narrower part of the subsurface only because of their low velocities. Therefore detailed modelling of small-scale structural anomalies imaged with MCS data within the GHSZ were undertaken in order to look for promising targets of MEBO drilling. An estimate of the expected hydrate and gas content is provided by comparison with published laboratory studies. Bialas, J., Klaucke, I. and Haeckel, M., 2014. FS MARIA S. MERIAN Fahrtbericht MSM-34 1&2 SUGAR Site, GEOMAR, Kiel. Popescu, I., Lericolais, G., Panin, N., De Batist, M. and Gillet, H., 2007. Seismic expression of gas and gas hydrates across the western Black Sea. Geo-Marine Letters, 27(2): 173-183.

Tsujal Project: New Geophysical Studies about Rivera PLATE and Jalisco Block (MEXICO)

NASA Astrophysics Data System (ADS)

Barba, D. C., Sr.; Nunez-Cornu, F. J.; Danobeitia, J.; Bartolome, R.; Bandy, W. L.; Escudero, C. R.; Cameselle, A. L.; Espindola de Castro, J. M., Sr.; Prada, M.; Nunez, D.; Zamora Camacho, A.; Gomez, A.; Ortiz, M.

2014-12-01

During spring and summer of 2014, it has been carried out the first geophysical fieldwork of the project entitled "Crustal characterization of the Rivera Plate-Jalisco Block boundary and its implications for seismic and tsunami hazard assessment (TSUJAL)". This is project is the result of a wide scientific collaboration between institutions of Mexico and Spain with the main aim of studying the lithospheric structure in Rivera and North American Plates convergence regions and Jalisco Block, and, also, identifying submarine structures that could be tsunamigenic sources. The first phase of this project was carried out in February and March of 2014. More than 5200 km of Multichannel Seismic Reflection (MCS) data were acquired, together with multibeam and parametric soundings and potential fields (gravity and magnetism) data. Wide Angle profiling were recorded deploying 16 OBS in 32 locations, offshore Jalisco and Nayarit regions Onshore, a network of 100 short period seismic portable stations were deployed in 240 locations along 5 seismic lines of 200-300 km length that worked combined with Seismological Network of Jalisco State (SisVOc). In addition, 8 land seismic stations were installed in Marías Islands and Isabel Island. These instruments registered, in continuous mode, the source energy was generated by big airgun array of 5800 ci, shooting every 120 s. The British vessel RRS James Cook, which participated in this project as a part of the exchange program between Spanish and English scientific vessels, was responsible of carrying out the MCS profiles and the deployment of OBS. For them, it was used a 6 km length digital streamer and airgun array of high capacity. Moreover, the ARM Holzinger and RV El Puma participated in this project and were provided by the Mexican Navy and UNAM, respectively. The second phase of this project was carried out in June 2014. 100 short period seismic stations were installed along one seismic profile from La Caldera de la Primavera (Guadalajara) to Barra de Navidad (Jalisco coast), covering 200 km distance. The new data acquired during TSUJAL project provide a dense sampling of studied plates and give new seismic images about continental deformation along and across the subduction zone, accretionary wedge size, about contact between Rivera and North American Plates.

Hyperphagia, lower body temperature, and reduced running wheel activity precede development of morbid obesity in New Zealand obese mice.

PubMed

Jürgens, Hella S; Schürmann, Annette; Kluge, Reinhart; Ortmann, Sylvia; Klaus, Susanne; Joost, Hans-Georg; Tschöp, Matthias H

2006-04-13

Among polygenic mouse models of obesity, the New Zealand obese (NZO) mouse exhibits the most severe phenotype, with fat depots exceeding 40% of total body weight at the age of 6 mo. Here we dissected the components of energy balance including feeding behavior, locomotor activity, energy expenditure, and thermogenesis compared with the related lean New Zealand black (NZB) and obese B6.V-Lep(ob)/J (ob/ob) strains (11% and 65% fat at 23 wk, respectively). NZO mice exhibited a significant hyperphagia that, when food intake was expressed per metabolic body mass, was less pronounced than that of the ob/ob strain. Compared with NZB, NZO mice exhibited increased meal frequency, meal duration, and meal size. Body temperature as determined by telemetry with implanted sensors was reduced in NZO mice, but again to a lesser extent than in the ob/ob strain. In striking contrast to ob/ob mice, NZO mice were able to maintain a constant body temperature during a 20-h cold exposure, thus exhibiting a functioning cold-induced thermogenesis. No significant differences in spontaneous home cage activity were observed among NZO, NZB, and ob/ob strains. When mice had access to voluntary running wheels, however, running activity was significantly lower in NZO than NZB mice and even lower in ob/ob mice. These data indicate that obesity in NZO mice, just as in humans, is due to a combination of hyperphagia, reduced energy expenditure, and insufficient physical activity. Because NZO mice differ strikingly from the ob/ob strain in their resistance to cold stress, we suggest that the molecular defects causing hyperphagia in NZO mice are located distal from leptin and its receptor.

Services for domain specific developments in the Cloud

NASA Astrophysics Data System (ADS)

Schwichtenberg, Horst; Gemuend, André

2015-04-01

We will discuss and demonstrate the possibilities of new Cloud Services where the complete development of code is in the Cloud. We will discuss the possibilities of such services where the complete development cycle from programing to testing is in the cloud. This can be also combined with dedicated research domain specific services and hide the burden of accessing available infrastructures. As an example, we will show a service that is intended to complement the services of the VERCE projects infrastructure, a service that utilizes Cloud resources to offer simplified execution of data pre- and post-processing scripts. It offers users access to the ObsPy seismological toolbox for processing data with the Python programming language, executed on virtual Cloud resources in a secured sandbox. The solution encompasses a frontend with a modern graphical user interface, a messaging infrastructure as well as Python worker nodes for background processing. All components are deployable in the Cloud and have been tested on different environments based on OpenStack and OpenNebula. Deployments on commercial, public Clouds will be tested in the future.

Morphological and biochemical alterations of skeletal muscles from the genetically obese (ob/ob) mouse.

PubMed

Kemp, J G; Blazev, R; Stephenson, D G; Stephenson, G M M

2009-08-01

Knowledge of the morphological and biochemical alterations occurring in skeletal muscles of obese animals is relatively limited, particularly with respect to non-limb muscles and relationship to fibre type. Sternomastoid (SM; fast-twitch), extensor digitorum longus (EDL; fast-twitch), and soleus (SOL; mixed) muscles of ob/ob mouse (18-22 weeks) were examined with respect to size (mass, muscle mass-to-body mass ratio, cross-sectional area (CSA)), fibre CSA, protein content, myosin heavy chain (MHC) content, MHC isoform (MHC(i)) composition, MHC(i)-based fibre type composition, and lactate dehydrogenase isoenzyme (LDH(iso)) composition. Compared with (control) muscles from lean mice, all the three muscles from ob/ob mice were smaller in size (by 13-30%), with SM and EDL being the most affected. The CSA of IIB and IIB+IID fibres (the predominant fibre types in SM and EDL muscles) was markedly smaller (by approximately 30%) in ob/ob mice, consistent with differences in muscle size. Total protein content (normalised to muscle mass) was significantly lower in EDL (-9.7%) and SOL (-14.1%) muscles of ob/ob mice, but there were no differences between SM, EDL, and SOL muscles from the two animal groups with respect to MHC content (also normalised to muscle mass). Electrophoretic analyses of MHC(i) composition in whole muscle homogenates and single muscle fibres showed a shift towards slower MHC(i) content, slower MHC(i) containing fibres, and a greater proportion of hybrid fibres in all the three muscles of ob/ob mice, with a shift towards a more aerobic-oxidative phenotype also observed with respect to LDH(iso) composition. This study showed that SM, EDL, and SOL muscles of ob/ob mice display size reductions to an extent that seems to be largely related to fibre type composition, and a shift in fibre type composition that may result from a process of structural remodelling, as suggested by the increased proportion of hybrid fibres in muscles of ob/ob mice.

All-trans retinoic acid stimulates gene expression of the cardioprotective natriuretic peptide system and prevents fibrosis and apoptosis in cardiomyocytes of obese ob/ob mice.

PubMed

Manolescu, Daniel-Constantin; Jankowski, Marek; Danalache, Bogdan A; Wang, Donghao; Broderick, Tom L; Chiasson, Jean-Louis; Gutkowska, Jolanta

2014-10-01

In hypertensive rodents, retinoic acid (RA) prevents adverse cardiac remodelling and improves myocardial infarction outcome, but its role in obesity-related changes of cardiac tissue are unclear. We hypothesized that all-trans RA (ATRA) treatment will improve the cardioprotective oxytocin-natriuretic peptides (OT-NP) system, preventing apoptosis and collagen accumulation in hearts of ob/ob mice, a mouse model of obesity and insulin resistance. Female 9-week-old B6.V-Lep/J ob/ob mice (n = 16) were divided into 2 groups: 1 group (n = 8) treated with 100 μg of ATRA dissolved in 100 μL of corn oil (vehicle) delivered daily (∼2 μg·g body weight(-1)·day(-1)) by stomach intubation for 16 days, and 1 group (n = 8) that received the vehicle alone. A group of nonobese littermate mice (n = 9) served as controls. Ob/ob mice exhibited obesity, hyperglycaemia, and downregulation of the cardiac OT-NP system, including the mRNA for the transcription factor GATA4, OT receptor and brain NP, and the protein expression for endothelial nitric oxide synthase. Hearts from ob/ob mice also demonstrated increased apoptosis and collagen accumulation. ATRA treatment induced weight loss and decreased adipocytes diameter in the visceral fat, thus reducing visceral obesity, which is associated with a high risk for cardiovascular disease. RA treatment was associated with a reduction in hyperglycemia and a normalization of the OT-NP system's expression in the hearts of ob/ob mice. Furthermore, ATRA treatment prevented apoptosis and collagen accumulation in hearts of ob/ob mice. The present study indicates that ATRA treatment was effective in restoring the cardioprotective OT-NP system and in preventing abnormal cardiac remodelling in the ob/ob mice.

Image quality and diagnostic performance of free-breathing diffusion-weighted imaging for hepatocellular carcinoma.

PubMed

Takayama, Yukihisa; Nishie, Akihiro; Asayama, Yoshiki; Ishigami, Kousei; Kakihara, Daisuke; Ushijima, Yasuhiro; Fujita, Nobuhiro; Shirabe, Ken; Takemura, Atsushi; Honda, Hiroshi

2017-05-18

To retrospectively evaluate the diagnostic performance of free-breathing diffusion-weighted imaging (FB-DWI) with modified imaging parameter settings for detecting hepatocellular carcinomas (HCCs). Fifty-one patients at risk for HCC were scanned with both FB-DWI and respiratory-triggered DWI with the navigator echo respiratory-triggering technique (RT-DWI). Qualitatively, the sharpness of the liver contour, the image noise and the chemical shift artifacts on each DWI with b -values of 1000 s/mm 2 were independently evaluated by three radiologists using 4-point scoring. We compared the image quality scores of each observer between the two DWI methods, using the Wilcoxon signed-rank test. Quantitatively, we compared the signal-to-noise ratios (SNRs) of the liver parenchyma and lesion-to-nonlesion contrast-to-noise ratios (CNRs) after measuring the signal intensity on each DWI with a b-factor of 1000 s/mm 2 . The average SNRs and CNRs between the two DWI methods were compared by the paired t-test. The detectability of HCC on each DWI was also analyzed by three radiologists. The detectability provided by the two DWI methods was compared using McNemar's test. For all observers, the averaged image quality scores of FB-DWI were: Sharpness of the liver contour [observer (Obs)-1, 3.08 ± 0.81; Obs-2, 2.98 ± 0.73; Obs-3, 3.54 ± 0.75], those of the distortion (Obs-1, 2.94 ± 0.50; Obs-2, 2.71 ± 0.70; Obs-3, 3.27 ± 0.53), and the chemical shift artifacts (Obs-1, 3.38 ± 0.60; Obs-2, 3.15 ± 1.07; Obs-3, 3.21 ± 0.85). The averaged image quality scores of RT-DWI were: Sharpness of the liver contour (Obs-1, 2.33 ± 0.65; Obs-2, 2.37 ± 0.74; Obs-3, 2.75 ± 0.81), distortion (Obs-1, 2.81 ± 0.56; Obs-2, 2.25 ± 0.74; Obs-3, 2.96 ± 0.71), and the chemical shift artifacts (Obs-1, 2.92 ± 0.59; Obs-2, 2.21 ± 0.85; Obs-3, 2.77 ± 1.08). All image quality scores of FB-DWI were significantly higher than those of RT-DWI ( P < 0.05). The average SNR of the normal liver parenchyma by FB-DWI (11.0 ± 4.8) was not significantly different from that shown by RT-DWI (11.0 ± 5.0); nor were the lesion-to-nonlesion CNRs significantly different (FB-DWI, 21.4 ± 17.7; RT-DWI, 20.1 ± 15.1). For all three observers, the detectability of FB-DWI (Obs-1, 43.6%; Obs-2, 53.6%; and Obs-3, 45.0%) was significantly higher than that of RT-DWI (Obs-1, 29.1%; Obs-2, 43.6%; and Obs-3, 34.5%) ( P < 0.05). FB-DWI showed better image quality and higher detectability of HCC compared to RT-DWI, without significantly reducing the SNRs of the liver parenchyma and lesion-to-nonlesion CNRs.

Image quality and diagnostic performance of free-breathing diffusion-weighted imaging for hepatocellular carcinoma

PubMed Central

Takayama, Yukihisa; Nishie, Akihiro; Asayama, Yoshiki; Ishigami, Kousei; Kakihara, Daisuke; Ushijima, Yasuhiro; Fujita, Nobuhiro; Shirabe, Ken; Takemura, Atsushi; Honda, Hiroshi

2017-01-01

AIM To retrospectively evaluate the diagnostic performance of free-breathing diffusion-weighted imaging (FB-DWI) with modified imaging parameter settings for detecting hepatocellular carcinomas (HCCs). METHODS Fifty-one patients at risk for HCC were scanned with both FB-DWI and respiratory-triggered DWI with the navigator echo respiratory-triggering technique (RT-DWI). Qualitatively, the sharpness of the liver contour, the image noise and the chemical shift artifacts on each DWI with b-values of 1000 s/mm2 were independently evaluated by three radiologists using 4-point scoring. We compared the image quality scores of each observer between the two DWI methods, using the Wilcoxon signed-rank test. Quantitatively, we compared the signal-to-noise ratios (SNRs) of the liver parenchyma and lesion-to-nonlesion contrast-to-noise ratios (CNRs) after measuring the signal intensity on each DWI with a b-factor of 1000 s/mm2. The average SNRs and CNRs between the two DWI methods were compared by the paired t-test. The detectability of HCC on each DWI was also analyzed by three radiologists. The detectability provided by the two DWI methods was compared using McNemar’s test. RESULTS For all observers, the averaged image quality scores of FB-DWI were: Sharpness of the liver contour [observer (Obs)-1, 3.08 ± 0.81; Obs-2, 2.98 ± 0.73; Obs-3, 3.54 ± 0.75], those of the distortion (Obs-1, 2.94 ± 0.50; Obs-2, 2.71 ± 0.70; Obs-3, 3.27 ± 0.53), and the chemical shift artifacts (Obs-1, 3.38 ± 0.60; Obs-2, 3.15 ± 1.07; Obs-3, 3.21 ± 0.85). The averaged image quality scores of RT-DWI were: Sharpness of the liver contour (Obs-1, 2.33 ± 0.65; Obs-2, 2.37 ± 0.74; Obs-3, 2.75 ± 0.81), distortion (Obs-1, 2.81 ± 0.56; Obs-2, 2.25 ± 0.74; Obs-3, 2.96 ± 0.71), and the chemical shift artifacts (Obs-1, 2.92 ± 0.59; Obs-2, 2.21 ± 0.85; Obs-3, 2.77 ± 1.08). All image quality scores of FB-DWI were significantly higher than those of RT-DWI (P < 0.05). The average SNR of the normal liver parenchyma by FB-DWI (11.0 ± 4.8) was not significantly different from that shown by RT-DWI (11.0 ± 5.0); nor were the lesion-to-nonlesion CNRs significantly different (FB-DWI, 21.4 ± 17.7; RT-DWI, 20.1 ± 15.1). For all three observers, the detectability of FB-DWI (Obs-1, 43.6%; Obs-2, 53.6%; and Obs-3, 45.0%) was significantly higher than that of RT-DWI (Obs-1, 29.1%; Obs-2, 43.6%; and Obs-3, 34.5%) (P < 0.05). CONCLUSION FB-DWI showed better image quality and higher detectability of HCC compared to RT-DWI, without significantly reducing the SNRs of the liver parenchyma and lesion-to-nonlesion CNRs. PMID:28588750

Stratigraphic Profiles for Selected Hanford Site Seismometer Stations and Other Locations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Last, George V.

2014-02-01

Stratigraphic profiles were constructed for eight selected Hanford Site seismometer stations, five Hanford Site facility reference locations, and seven regional three-component broadband seismometer stations. These profiles provide interpretations of the subsurface layers to support estimation of ground motions from past earthquakes, and the prediction of ground motions from future earthquakes. In most cases these profiles terminated at the top of the Wanapum Basalt, but at selected sites profiles were extended down to the top of the crystalline basement. The composite one-dimensional stratigraphic profiles were based primarily on previous interpretations from nearby boreholes, and in many cases the nearest deep boreholemore » is located kilometers away.« less

A Brief Test of the Tokyo Sokushin VSE-355G3 Strong Motion Velocity Seismometer

USGS Publications Warehouse

Hutt, Charles R.; Evans, John R.; Yokoi, Isamu

2008-01-01

The VSE-355G3 seismometer is a broadband seismometer (called a 'servo velocity meter' by Tokyo Sokushin) with a specified clip level of 2 m/s and a flat response to earth velocity from 0.008 Hertz (Hz) to 70 Hz. Mr. Yokoi and Mr. Kurahashi of Tokyo Sokushin shipped one instrument to the U. S. Geological Survey's Albuquerque Seismological Laboratory (ASL) for testing in early September 2007. They gave a presentation on this instrument and some of their other products to the authors and others on September 6, 2007. Testing of the VSE-355G3, Serial Number 70520, commenced on Friday, September 7, 2007.

Guidelines for Standardized Testing of Broadband Seismometers and Accelerometers

USGS Publications Warehouse

Hutt, Charles R.; Evans, John R.; Followill, Fred; Nigbor, Robert L.; Wielandt, Erhard

2010-01-01

Testing and specification of seismic and earthquake-engineering sensors and recorders has been marked by significant variations in procedures and selected parameters. These variations cause difficulty in comparing such specifications and test results. In July 1989, and again in May 2005, the U.S. Geological Survey hosted international pub-lic/private workshops with the goal of defining widely accepted guidelines for the testing of seismological inertial sensors, seismometers, and accelerometers. The Proceedings of the 2005 workshop have been published and include as appendix 6 the report of the 1989 workshop. This document represents a collation and rationalization of a single set of formal guidelines for testing and specifying broadband seismometers and accelerometers.

Microbial mineral colonization across a subsurface redox transition zone

DOE PAGES

Converse, Brandon J.; McKinley, James P.; Resch, Charles T.; ...

2015-08-28

Here our study employed 16S rRNA gene amplicon pyrosequencing to examine the hypothesis that chemolithotrophic Fe(II)-oxidizing bacteria (FeOB) would preferentially colonize the Fe(II)-bearing mineral biotite compared to quartz sand when the minerals were incubated in situ within a subsurface redox transition zone (RTZ) at the Hanford 300 Area site in Richland, WA, USA. The work was motivated by the recently documented presence of neutral-pH chemolithotrophic FeOB capable of oxidizing structural Fe(II) in primary silicate and secondary phyllosilicate minerals in 300 Area sediments and groundwater (Benzine et al., 2013). Sterilized portions of sand+biotite or sand alone were incubated in situ formore » 5 months within a multilevel sampling (MLS) apparatus that spanned a ca. 2-m interval across the RTZ in two separate groundwater wells. Parallel MLS measurements of aqueous geochemical species were performed prior to deployment of the minerals. Contrary to expectations, the 16S rRNA gene libraries showed no significant difference in microbial communities that colonized the sand+biotite vs. sand-only deployments. Both mineral-associated and groundwater communities were dominated by heterotrophic taxa, with organisms from the Pseudomonadaceae accounting for up to 70% of all reads from the colonized minerals. These results are consistent with previous results indicating the capacity for heterotrophic metabolism (including anaerobic metabolism below the RTZ) as well as the predominance of heterotrophic taxa within 300 Area sediments and groundwater. Although heterotrophic organisms clearly dominated the colonized minerals, several putative lithotrophic (NH 4 +, H 2, Fe(II), and HS - oxidizing) taxa were detected in significant abundance above and within the RTZ. Such organisms may play a role in the coupling of anaerobic microbial metabolism to oxidative pathways with attendant impacts on elemental cycling and redox-sensitive contaminant behavior in the vicinity of the RTZ.« less

The soluble leptin receptor.

PubMed

Schaab, Michael; Kratzsch, Juergen

2015-10-01

The adipokine leptin realizes signal transduction via four different leptin receptor (OB-R) isoforms. The amount of functionally active OB-R, however, is affected by constitutive shedding of the extracellular domain. The product of the cleavage process, the so-called soluble leptin receptor (sOB-R), is the main binding protein for leptin in human blood and modulates its bioavailability. Concentrations of sOB-R are differentially regulated in metabolic disorders, such as type 1 diabetes mellitus or obesity, and can, therefore, enhance or reduce leptin sensitivity. Lipotoxicity and apoptosis increase OB-R cleavage via ADAM10-dependent mechanisms. In contrast, although increased sOB-R concentrations seem to directly inhibit leptin effects, reduced amounts of sOB-R may reflect decreased membrane expression of OB-R. These findings, in part, explain alterations of leptin sensitivity that are associated with changes in serum sOB-R concentrations seen in metabolic disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

Leptin receptor mRNA in rat brain astrocytes

PubMed Central

Hsuchou, Hung; Pan, Weihong; Barnes, Maria J.; Kastin, Abba J.

2009-01-01

We recently reported that mouse astrocytes express leptin receptors (ObR), and that obesity induces upregulation of astrocytic ObR. To provide further evidence of the importance of astrocytic ObR expression, we performed double-labeling fluorescent in-situ hybridization (FISH) and immunohistochemistry in the rat hypothalamus. Laser confocal microscopic image analysis showed that ObR mRNA was present in glial fibrillary acidic protein (+) cells that show distinctive astrocytic morphology as well as in neurons. In addition to the presence of ObR mRNA, ObR protein was shown in both astrocytes and neurons in the rat hypothalamus by double-labeling immunohistochemistry. In cultured rat C6 astrocytoma cells treated with different doses of lipopolysaccharide for 6 h, the mRNA for ObRa or ObRb did not show significant changes, as measured by quantitative RT-PCR. However, the protein expression of both ObRa and ObRb, determined by western blotting, was increased after the C6 cells were treated with either lipopolysaccharide or tumor necrosis factor-α. The results indicate that astrocytic ObR expression is present in rats as well as mice, and that it probably plays a role in the neuroinflammatory response. PMID:19747514

Ocean Bottom Seismograph Performance during the Cascadia Initiative

NASA Astrophysics Data System (ADS)

Aderhold, K.; Evers, B.

2015-12-01

The Ocean Bottom Seismograph Instrument Pool (OBSIP) provides instrumentation and operations support for the Cascadia Initiative community experiment. This experiment investigates geophysical processes across the Cascadia subduction zone through a combination of onshore and offshore seismic data. The recovery of Year 4 instruments in September 2015 marks the conclusion of a multi-year experiment that utilized 60 ocean-bottom seismographs (OBSs) specifically designed for the subduction zone boundary, including shallow/deep water deployments and active fisheries. The new instruments feature trawl-resistant enclosures designed by Lamont-Doherty Earth Observatory (LDEO) and Scripps Institution of Oceanography (SIO) for shallow deployment [water depth ≤ 500 m], as well as new deep-water instruments designed by Woods Hole Oceanographic Institute (WHOI). Existing OBSIP instruments were also deployed along the Blanco Transform Fault and on the Gorda Plate through complementary experiments. Stations include differential pressure gauges (DPG) and absolute pressure gauges (APG). All data collected from the Cascadia, Blanco, and Gorda deployments will be freely available through the Incorporated Research Institutions for Seismology (IRIS) Data Management Center (DMC). The Cascadia Initiative is the largest amphibious seismic experiment undertaken to date and demonstrates an effective structure for community experiments through collaborative efforts from the Cascadia Initiative Expedition Team (CIET), OBSIP (institutional instrument contributors [LDEO, SIO, WHOI] and Management Office [IRIS]), and the IRIS DMC. The successes and lessons from Cascadia are a vital resource for the development of a Subduction Zone Observatory (SZO). To guide future efforts, we investigate the quality of the Cascadia OBS data using basic metrics such as instrument recovery and more advanced metrics such as noise characteristics through power spectral density analysis. We also use this broad and diverse deployment to determine how water depth and instrument shielding influence recorded data. Additionally, multi-year data collection allows us to identify temporal noise trends so that we can take advantage of quieter seasons for future deployments.

Teaching Geophysics with a Vertical-Component Seismometer

ERIC Educational Resources Information Center

van Wijk, Kasper; Channel, Ted; Viskupic, Karen; Smith, Martin L.

2013-01-01

Earthquakes are some of the more dramatic expressions of the dynamics of our planet. The sudden release of stress built up slowly by tectonic or volcanic processes often has far-reaching consequences, and can be measured (in classrooms) around the world. This is one reason why designing and building seismometers has been a popular activity, and…

Chronic ethanol consumption lessens the gain of body weight, liver triglycerides, and diabetes in obese ob/ob mice.

PubMed

Fromenty, Bernard; Vadrot, Nathalie; Massart, Julie; Turlin, Bruno; Barri-Ova, Nadège; Lettéron, Philippe; Fautrel, Alain; Robin, Marie-Anne

2009-10-01

Clinical studies suggest that moderate alcohol consumption can have beneficial effects, in particular regarding cardiovascular events, insulin resistance, and type 2 diabetes. In this study, lean and obese diabetic ob/ob mice were submitted or not to chronic ethanol intake via the drinking water for 6 months, which was associated with moderate levels of plasma ethanol. Plasma levels of alanine aminotransferase and aspartate aminotransferase were not increased by alcohol intake. Ethanol consumption progressively reduced the gain of body weight in ob/ob mice, but not in lean mice, and this was observed despite higher calorie intake. Increased plasma free fatty acids and glycerol in ethanol-treated ob/ob mice suggested peripheral lipolysis. Glycemia and insulinemia were significantly reduced, whereas adiponectinemia was increased in ethanol-treated ob/ob mice. Liver weight and triglycerides were significantly decreased in ethanol-treated ob/ob mice, and this was associated with less microvesicular steatosis. Hepatic levels of AMP-activated protein kinase and the phosphorylated form of acetyl-CoA carboxylase were higher in ethanol-treated ob/ob mice, suggesting better fatty acid oxidation. However, hepatic mRNA expression of several lipogenic genes was not reduced by ethanol consumption. Finally, mild oxidative stress was noticed in the liver of ethanol-treated mice, regardless of their genotype. Hence, our data are in keeping with clinical studies suggesting that moderate ethanol intake can have beneficial effects on type 2 diabetes and insulin sensitivity, at least in part through increased levels of plasma adiponectin. However, further studies are needed to determine whether long-term drinking of light-to-moderate amounts of ethanol is safe for the liver.

Comparison of onboard low-field magnetic resonance imaging versus onboard computed tomography for anatomy visualization in radiotherapy.

PubMed

Noel, Camille E; Parikh, Parag J; Spencer, Christopher R; Green, Olga L; Hu, Yanle; Mutic, Sasa; Olsen, Jeffrey R

2015-01-01

Onboard magnetic resonance imaging (OB-MRI) for daily localization and adaptive radiotherapy has been under development by several groups. However, no clinical studies have evaluated whether OB-MRI improves visualization of the target and organs at risk (OARs) compared to standard onboard computed tomography (OB-CT). This study compared visualization of patient anatomy on images acquired on the MRI-(60)Co ViewRay system to those acquired with OB-CT. Fourteen patients enrolled on a protocol approved by the Institutional Review Board (IRB) and undergoing image-guided radiotherapy for cancer in the thorax (n = 2), pelvis (n = 6), abdomen (n = 3) or head and neck (n = 3) were imaged with OB-MRI and OB-CT. For each of the 14 patients, the OB-MRI and OB-CT datasets were displayed side-by-side and independently reviewed by three radiation oncologists. Each physician was asked to evaluate which dataset offered better visualization of the target and OARs. A quantitative contouring study was performed on two abdominal patients to assess if OB-MRI could offer improved inter-observer segmentation agreement for adaptive planning. In total 221 OARs and 10 targets were compared for visualization on OB-MRI and OB-CT by each of the three physicians. The majority of physicians (two or more) evaluated visualization on MRI as better for 71% of structures, worse for 10% of structures, and equivalent for 14% of structures. 5% of structures were not visible on either. Physicians agreed unanimously for 74% and in majority for > 99% of structures. Targets were better visualized on MRI in 4/10 cases, and never on OB-CT. Low-field MR provides better anatomic visualization of many radiotherapy targets and most OARs as compared to OB-CT. Further studies with OB-MRI should be pursued.

Hydrogen sulfide improves diabetic wound healing in ob/ob mice via attenuating inflammation.

PubMed

Zhao, Huichen; Lu, Shengxia; Chai, Jiachao; Zhang, Yuchao; Ma, Xiaoli; Chen, Jicui; Guan, Qingbo; Wan, Meiyan; Liu, Yuantao

2017-09-01

The proposed mechanisms of impaired wound healing in diabetes involve sustained inflammation, excess oxidative stress and compromised agiogenesis. Hydrogen sulfide (H 2 S) has been reported to have multiple biological activities. We aim to investigate the role of H 2 S in impaired wound healing in ob/ob mice and explore the possible mechanisms involved. Full-thickness skin dorsal wounds were created on ob/ob mice and C57BL/6 mice. Cystathionine-γ-lyase (CSE) expression and H 2 S production were determined in granulation tissues of the wounds. Effects of NaHS on wound healing were evaluated. Inflammation and angiogenesis in granulation tissues of the wounds were examined. CSE expression, and H 2 S content were significantly reduced in granulation tissues of wounds in ob/ob mice compared with control mice. NaHS treatment significantly improved wound healing in ob/ob mice, which was associated with reduced neutrophil and macrophage infiltration, decreased production of tumor necrosis factor (TNF)-α, interleukin (IL)-6. NaHS treatment decreased metalloproteinase (MMP)-9, whereas increased collagen deposition and vascular-like structures in granulation tissues of wounds in ob/ob mice. CSE down-regulation may play a role in the pathogenesis of diabetic impaired wound healing. Exogenous H 2 S could be a potential agent to improve diabetic impaired wound healing by attenuating inflammation and increasing angiogenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

Hepatic steatosis inhibits autophagic proteolysis via impairment of autophagosomal acidification and cathepsin expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inami, Yoshihiro; Yamashina, Shunhei, E-mail: syamashi@juntendo.ac.jp; Izumi, Kousuke

2011-09-09

Highlights: {yields} Acidification of autophagosome was blunted in steatotic hepatocytes. {yields} Hepatic steatosis did not disturb fusion of isolated autophagosome and lysosome. {yields} Proteinase activity of cathepsin B and L in autolysosomes was inhibited by steatosis. {yields} Hepatic expression of cathepsin B and L was suppressed by steatosis. -- Abstract: Autophagy, one of protein degradation system, contributes to maintain cellular homeostasis and cell defense. Recently, some evidences indicated that autophagy and lipid metabolism are interrelated. Here, we demonstrate that hepatic steatosis impairs autophagic proteolysis. Though accumulation of autophagosome is observed in hepatocytes from ob/ob mice, expression of p62 was augmentedmore » in liver from ob/ob mice more than control mice. Moreover, degradation of the long-lived protein leucine was significantly suppressed in hepatocytes isolated from ob/ob mice. More than 80% of autophagosomes were stained by LysoTracker Red (LTR) in hepatocytes from control mice; however, rate of LTR-stained autophagosomes in hepatocytes were suppressed in ob/ob mice. On the other hand, clearance of autolysosomes loaded with LTR was blunted in hepatocytes from ob/ob mice. Although fusion of isolated autophagosome and lysosome was not disturbed, proteinase activity of cathepsin B and L in autolysosomes and cathepsin B and L expression of liver were suppressed in ob/ob mice. These results indicate that lipid accumulation blunts autophagic proteolysis via impairment of autophagosomal acidification and cathepsin expression.« less

A novel approach to imaging extinct seafloor massive sulphides (eSMS) by using ocean bottom seismometer data from the Blue Mining project

NASA Astrophysics Data System (ADS)

Gil, A.; Chidlow, K. L.; Vardy, M. E.; Bialas, J.; Schroeder, H.; Stobbs, I. J.; Gehrmann, R. A. S.; North, L. J.; Minshull, T. A.; Petersen, S.; Murton, B. J.

2017-12-01

Seafloor massive sulphide (SMS) deposits have generated great interest regarding their formation and composition, since their discovery in 1977. SMS deposits form through hydrothermal circulation and are therefore commonly found near hydrothermal vent sites. The high base (Cu, Zn) and precious metal (Au, Ag) content has interested mining companies, due to their potentially high economic value. Currently, the possibility of mining extinct seafloor massive sulphides (eSMS) deposits has opened a debate about their environmentally and economically sustainable exploitation. A major goal is the rapid exploration and assessment of deposit structure and volume. This is challenging due to their small dimensions (100s m diameter) and typically great water depths (> 3000 mbsl). Here we present a novel approach combining seismic reflection/refraction forward modelling to data acquired from the TAG hydrothermal field (26ºN, Mid-Atlantic Ridge, 3500mbsl) to image deep-water eSMS deposits. In May 2016, the RV METEOR shot 30, short (<10km) MSC profiles across the TAG area. The data were recorded on a dense cluster (<75 m apart) of ocean bottom seismometers (OBS) and were able to image the subsurface of several 300m diameter eSMS deposits. The results show that the eSMS deposits present high velocities (5.4-6.6 km/s) to depths 200m below the seafloor where they are hosted in a 500m thick low-velocity (3.0-3.7 km/s) layer of altered basalt. In contrast to active hydrothermal systems, we see no evidence in the eSMS of a low-velocity anhydrite layer. The velocity-depth models obtained from this innovative method have been combined with other methods to study these eSMS deposits, such as electromagnetics, rocks physics and drilling technics, and the results are shown to concur, yielding information about deposit structure at depth. For example, the high-velocity layer extends deeper than the conductive layer, indicating a deep stock work of low-connectivity sulphides beneath a main ore body of more massive sulphide. These geophysical methods allow a better constraint on the volume of sulphide at typical SMS with implications for the metal budget within oceanic crust. This work was funded by the European Union's `Blue Mining' project, n˚ 604500.

Proteomic analysis of oil bodies in mature Jatropha curcas seeds with different lipid content.

PubMed

Liu, Hui; Wang, Cuiping; Chen, Fan; Shen, Shihua

2015-01-15

To reveal the difference among three mature Jatropha curcas seeds (JcVH, variant with high lipid content; JcW, wild type and JcVL, variant with low lipid content) with different lipid content, comparative proteomics was employed to profile the changes of oil body (OB) associated protein species by using gels-based proteomic technique. Eighty-three protein species were successfully identified through LTQ-ES-MS/MS from mature JcW seeds purified OBs. Two-dimensional electrophoresis analysis of J. curcas OB associated protein species revealed they had essential interactions with other organelles and demonstrated that oleosin and caleosin were the most abundant OB structural protein species. Twenty-eight OB associated protein species showed significant difference among JcVH, JcW and JcVL according to statistical analysis. Complementary transient expression analysis revealed that calcium ion binding protein (CalBP) and glycine-rich RNA binding protein (GRP) were well targeted in OBs apart from the oleosins. This study demonstrated that ratio of lipid content to caleosins abundance was involved in the regulation of OB size, and the mutant induced by ethylmethylsulfone treatment might be related to the caleosin like protein species. These findings are important for biotechnological improvement with the aim to alter the lipid content in J. curcas seeds. The economic value of Jatropha curcas largely depends on the lipid content in seeds which are mainly stored in the special organelle called oil bodies (OBs). In consideration of the biological importance and applications of J. curcas OB in seeds, it is necessary to further explore the components and functions of J. curcas OBs. Although a previous study concerning the J. curcas OB proteome revealed oleosins were the major OB protein component and additional protein species were similar to those in other oil seed plants, these identified OB associated protein species were corresponding to the protein bands instead of protein spots in the electrophoresis gels. Furthermore, the interaction of OB associated protein species and their contribution to OB formation and stabilization are still blank. In this study, with the overall object of profiling OB protein species from mature J. curcas seeds with different lipid content, we provided a setting of comparative OB proteomics with biochemical data and transient expression to explore the core of OB associated protein species involved in the regulation of OB size and lipid accumulation. The results were important for biotechnological improvement with the aim to a global modification of lipid storage in J. curcas seeds. Meanwhile, this study gave insight into possible associations between OBs and other organelles in mature J. curcas seeds. It may represent new aspects of the biological functions of the OBs during the oil mobilization. Combined the technique of transient transformation, a newly reported protein species, glycine-rich RNA binding protein (GRP) was successfully targeted in OBs. Therefore, further molecular analysis of these protein species is warranted to verify this association and what role they have in OBs. Copyright © 2014 Elsevier B.V. All rights reserved.

Australian Seismometers in Schools - eyes on seismology

NASA Astrophysics Data System (ADS)

Salmon, M.; Balfour, N.; Sambridge, M.

2014-12-01

The Australian Seismometers in Schools (AuSIS) program has installed 42 research quality broadband seismometers in schools around Australia. The school's infrastructure allows for real time data transfers, and eager young students monitor the instruments and report any recorded events. The reporting feature ("Caught it? Report it!") through our website works as a crude type of detection to inform us of what instruments pick up the earthquakes. It also has the added benefits of keeping schools engaged in the program, ongoing learning about earth science and geography, and obviously keeps them returning to our website. A network of professional and amateur seismologists provides support to the schools and helps promote earth science education and earthquake risk awareness. The data is publically available through the IRIS DMC and is used by not just our volunteers but also by government departments, universities and private agencies for research and monitoring. One of the challenges has been to provide a way for schools and to interact with the real time data in an accessible format. We have achieved this through website and mobile app development alongside step-by step how to guides. These tools have the added advantage that they also allow schools without their own seismometer to connect with nearby schools that do. The government run national network of seismometers in Australia is sparse; the AuSIS program provides additional instruments that are now being incorporated into the national network for improved regional earthquake locations. Although schools are not the ideal site for broadband seismometers, the program has proven that with a well-chosen location within the school we can recover high quality data for much of the day. The schools are generally well distributed across the country enabling the program to supplement the national network at the same time as bringing earth science to rural communities that often miss out on this type of opportunity.

Short-period surface-wave phase velocities across the conterminous United States

NASA Astrophysics Data System (ADS)

Ekström, G.

2017-09-01

Surface-wave phase-velocity maps for the full footprint of the USArray Transportable Array (TA) across the conterminous United States are developed and tested. Three-component, long-period continuous seismograms recorded on more than 1800 seismometers, most of which were deployed for 18 months or longer, are processed using a noise cross-correlation technique to derive inter-station Love and Rayleigh dispersion curves at periods between 5 and 40 s. The phase-velocity measurements are quality controlled using an automated algorithm and then used in inversions for Love and Rayleigh phase-velocity models at discrete periods on a 0.25°-by-0.25° pixel grid. The robustness of the results is examined using comparisons of maps derived from subsets of the data. A winter-summer division of the cross-correlation data results in small model differences, indicating relatively minor sensitivity of the results to seasonal variations in the distribution of noise sources. Division of the dispersion data based on inter-station azimuth does not result in geographically coherent model differences, suggesting that azimuthal anisotropy at the regional scale is weak compared with variations in isotropic velocities and does not substantially influence the results for isotropic velocities. The phase-velocity maps and dispersion measurements are documented and made available as data products of the 10-year-long USArray TA deployment.

A low-noise MEMS accelerometer for unattended ground sensor applications

NASA Astrophysics Data System (ADS)

Speller, Kevin E.; Yu, Duli

2004-09-01

A low-noise micro-machined servo accelerometer has been developed for use in Unattended Ground Sensors (UGS). Compared to conventional coil-and-magnet based velocity transducers, this Micro-Electro-Mechanical System (MEMS) accelerometer offers several key benefits for battlefield monitoring. Many UGS require a compass to determine deployment orientation with respect to magnetic North. This orientation information is critical for determining the bearing of incoming signals. Conventional sensors with sensing technology based on a permanent magnet can cause interference with a compass when used in close proximity. This problem is solved with a MEMS accelerometer which does not require any magnetic materials. Frequency information below 10 Hz is valuable for identification of signal sources. Conventional seismometers used in UGS are typically limited in frequency response from 20 to 200 Hz. The MEMS accelerometer has a flat frequency response from DC to 5 kHz. The wider spectrum of signals received improves detection, classification and monitoring on the battlefield. The DC-coupled output of the MEMS accelerometer also has the added benefit of providing tilt orientation data for the deployed UGS. Other performance parameters of the MEMS accelerometer that are important to UGS such as size, weight, shock survivability, phase response, distortion, and cross-axis rejection will be discussed. Additionally, field test data from human footsteps recorded with the MEMS accelerometer will be presented.

Cascadia Initiative Reveals Accumulation of Buoyant Material Beneath the Subducting Juan de Fuca Plate

NASA Astrophysics Data System (ADS)

Hawley, W. B.; Allen, R. M.; Richards, M. A.

2015-12-01

The Cascadia Initiative is a four-year (2011-2015) amphibious seismic deployment that covers the Juan de Fuca plate and the Cascadia Subduction Zone. It is comprised of 70 broadband ocean-bottom seismometers that occupy 120 sites in total, as well as 27 land-based stations. This array offers a unique opportunity to study the 3D structure of a subduction zone in unprecedented detail. We present the results of an inversion using teleseismic body waves recorded by the Cascadia Initiative, EarthScope, and other regional and temporary networks in the Pacific Northwest. A low-velocity feature is visible beneath the subducting slab at shallow depths. Previous studies report ponding of low-viscosity, buoyant material at the top of the asthenosphere, unable to rise through the impermeable lithospheric lid. We show that as the lithospheric lid descends into the mantle, this material is not advected with it; rather, due to its own weakness and buoyancy, it accumulates at the subduction zone. Such material could be partly responsible for the rapid uplift and volcanism in the Coast Range of California, in the wake of the northward migration of the Mendocino Triple Junction. This newly observed feature may play an important role in the structure of subduction zones, but understanding the extent of that role on a global scale will require amphibious seismic deployments in other subduction zones.

Crustal and Upper Mantle S-velocity Structure From Receiver Functions Analisys Around Terra Nova Bay Base, Antartica

NASA Astrophysics Data System (ADS)

Piana Agostinetti, N.; Amato, A.; Cattaneo, M.; de Gori, P.; di Bona, M.

In the framework of the italian PNRA (Progetto Nazionale di Ricerche in Antartide), we have started to re-analize teleseismic waveforms recorded, using three-components seismometers (equipped with 5 seconds sensors, Lennartz 3D-5s), during five summer campaings, from 1993 to 2000. Seismic stations were deployed around Terra Nova Bay (TNB) italian base, from the sea to reach the interior of the Transantartic Moun- tains (TAM), the most striking example of nocontractional mountain belt. During the last campaingn (1999-2000) seismic stations were deployed deep into Northern Vic- toria Land to reach Rennik and Lillie Glaciers Area and George V coast region, the northest part of TAM. Our main goals were: to compute, using frequency-domanin deconvolution method by Di Bona [1998], Receiver Functions covering all the area around TNB italian antartic base; to map of Moho-depth and intercrustal S-waves ve- locity discontinuity from 1-D velocity model computed using Sambridge's inversion scheme [Sambridge,1999]; to analize new teleseimic waveforms recorded near TNB base: continuos recording, from 1999 to present, permits more accurate modelling S-velocity crustal structure in this critical area situated at the edge of the ipothetic rift [Stern and ten Brik, 1989; Stump and Fitzgerald, 1992; ten Brik et al., 1997]; to present final results from BACKTAM expedition.

Broadband characteristics of earthquakes recorded during a dome-building eruption at Mount St. Helens, Washington, between October 2004 and May 2005: Chapter 5 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

USGS Publications Warehouse

Horton, Stephen P.; Norris, Robert D.; Moran, Seth C.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

2008-01-01

From October 2004 to May 2005, the Center for Earthquake Research and Information of the University of Memphis operated two to six broadband seismometers within 5 to 20 km of Mount St. Helens to help monitor recent seismic and volcanic activity. Approximately 57,000 earthquakes identified during the 7-month deployment had a normal magnitude distribution with a mean magnitude of 1.78 and a standard deviation of 0.24 magnitude units. Both the mode and range of earthquake magnitude and the rate of activity varied during the deployment. We examined the time domain and spectral characteristics of two classes of events seen during dome building. These include volcano-tectonic earthquakes and lower-frequency events. Lower-frequency events are further classified into hybrid earthquakes, low-frequency earthquakes, and long-duration volcanic tremor. Hybrid and low-frequency earthquakes showed a continuum of characteristics that varied systematically with time. A progressive loss of high-frequency seismic energy occurred in earthquakes as magma approached and eventually reached the surface. The spectral shape of large and small earthquakes occurring within days of each other did not vary with magnitude. Volcanic tremor events and lower-frequency earthquakes displayed consistent spectral peaks, although higher frequencies were more favorably excited during tremor than earthquakes.

Dense Seismic Recordings of Two Surface-Detonated Chemical Explosions

NASA Astrophysics Data System (ADS)

Koper, K. D.; Hale, J. M.; Burlacu, R.; Goddard, K. J.; Trow, A.; Linville, L. M.; Stein, J. R.; Drobeck, D.; Leidig, M.

2015-12-01

In the summer of 2015 two controlled chemical explosions were carried out near Dugway, Utah. The 2 June 2015 explosion consisted of 30,000 lbs of ammonium nitrate fuel oil (ANFO) and the 22 July 2015 explosion consisted of 60,000 lbs of ANFO. The explosion centroids were 1-2 m above the Earth's surface and both created significant craters in the soft desert alluvium. To better understand the seismic source associated with surface explosions, we deployed an array of wireless, three-component, short-period (5 Hz corner frequency) seismometers for several days around each shot. For the first explosion, 46 receivers were deployed in a "lollipop" geometry that had a sparse ring at a radius of 1 km, and a dense stem with 100 m spacing for distances of 0.5-4.5 km. For the second explosion, 48 receivers were deployed similarly, but with a dense ring spaced in azimuthal increments of 10 degrees at a distance of 1 km, and a sparse stem (~500 m spacing) that extended to a distance of nearly 6 km. A rich variety of phases were recorded including direct P waves, refracted and reflected P waves, nearly monochromatic air-coupled Rayleigh waves, normally dispersed fundamental mode Rayleigh waves (Rg), primary airblast arrivals, some secondary airblast arrivals, and possibly tertiary airblast arrivals. There is also evidence of converted S waves on the radial components and possibly direct S energy on the radial and transverse components, although the transverse energy does not always possess a simple, coherent move-out with distance, implying that it might have a scattering origin. To aid in the phase identification, especially of the apparent SH and Love energy, we are currently performing tau-p, f-k, and particle motion analysis.

Seismic Waveform Modeling of Broadband Data From a Temporary High-Density Deployment in the Los Angeles Basin

NASA Astrophysics Data System (ADS)

Herrman, M.; Polet, J.

2016-12-01

A total of 73 broadband seismometers were deployed for a passive source seismic experiment called the Los Angeles Syncline Seismic Interferometry Experiment (LASSIE) from September to November of 2014. The purpose of this experiment was to collect high density seismic data for the Los Angeles Basin (LAB) to better understand basin structure and response. This research will use the data collected from LASSIE to assess and refine current velocity models of the LAB using a full waveform modeling approach. To this end we will compare seismograms recorded by LASSIE for a subset of the 53 earthquakes and quarry blasts located by the Southern California Seismic Network (SCSN) that occurred within or near the LAB during the deployment period to synthetic seismograms generated by the Frequency-Wavenumber (FK) code developed by Zhu and Rivera (2002). A first analysis of the data indicates that roughly 25 of the 53 events have waveforms with sufficiently high signal to noise ratio, providing approximately 500 seismograms that are of suitable quality for comparison. We observe significant changes in waveform characteristics between stations with a very small separation distance of approximately 1 km. Focal mechanisms for most of these events have been obtained from Dr. Egill Hauksson (personal communication). We will show comparisons between the broadband velocity waveforms recorded by stations across the LASSIE array and FK synthetics determined for a variety of 1D velocity models that have been developed for the LAB area (such as Hadley and Kanamori, 1977; Hauksson, 1989, 1995 and Magistrale, 1992). The results of these comparisons will be analyzed to provide additional constraints on the subsurface seismic velocity structure within the Los Angeles basin.

Recent Instrumentation Developments in the Global Seismographic Network (GSN)

NASA Astrophysics Data System (ADS)

Hafner, K.; Davis, J. P.; Wilson, D.

2016-12-01

One of the challenges facing the GSN is continuing to provide robust, uniform high-quality, very broadband, high-dynamic range recordings of ground motion data as the original primary seismometers age. Recently the GSN has been upgrading all stations with the next generation of digital data acquisition systems (DASs), which has significantly increased the station data availability. In 2012, the Department of Energy received an additional $5.7M to support GSN refurbishment. The funds were transferred to the USGS via a 5-year interagency agreement and have been used for developing the next generation of very broadband (VBB) sensors. The USGS Albuquerque Seismic Laboratory (ASL) received the first prototype of a very broadband borehole sensor (Streckeisen STS-6A) in November 2015. Initial testing showed this prototype met all the required sensor specifications. Three pre-production sensors are scheduled to arrive by late August 2016. We will present the results of testing these devices, as well as an update on other recent VBB sensor developments (Trillium T360) and how they compare to the performance of the STS-1 and other available sensors. Recent work at ASL and the USArray Transportable Array has shown that installing sensors in shallow postholes up to 10 meters deep can lead to significant improvement in data quality. The GSN is investigating the potential of installing borehole sensors at some GSN stations where the STS-1 has shown significant susceptibility to pier tilt, temperature instability, or cultural noise. The GSN is also broadening the types of sensors deployed at GSN stations. After initial testing at ASL and UCSD's Pinyon Flat test site, the first infrasound sensor deployment will take place in Fall 2016. We will present the results of these tests and descriptions of the initial deployment.

Seismic Structure of Perth Basin (Australia) and surroundings from Passive Seismic Deployments

NASA Astrophysics Data System (ADS)

Issa, N.; Saygin, E.; Lumley, D. E.; Hoskin, T. E.

2016-12-01

We image the subsurface structure of Perth Basin, Western Australia and surroundings by using ambient seismic noise data from 14 seismic stations recently deployed by University of Western Australia (UWA) and other available permanent stations from Geoscience Australia seismic network and the Australian Seismometers in Schools program. Each of these 14 UWA seismic stations comprises a broadband sensor and a high fidelity 3-component 10 Hz geophone, recording in tandem at 250 Hz and 1000 Hz. The other stations used in this study are equipped with short period and broadband sensors. In addition, one shallow borehole station is operated with eight 3 component geophones at depths of between 2 and 44 m. The network is deployed to characterize natural seismicity in the basin and to try and identify any microseismic activity across Darling Fault Zone (DFZ), bounding the basin to the east. The DFZ stretches to approximately 1000 km north-south in Western Australia, and is one of the longest fault zones on the earth with a limited number of detected earthquakes. We use seismic noise cross- and auto-correlation methods to map seismic velocity perturbations across the basin and the transition from DFZ to the basin. Retrieved Green's functions are stable and show clear dispersed waveforms. Travel times of the surface wave Green's functions from noise cross-correlations are inverted with a two-step probabilistic framework to map the absolute shear wave velocities as a function of depth. The single station auto-correlations from the seismic noise yields P wave reflectivity under each station, marking the major discontinuities. Resulting images show the shear velocity perturbations across the region. We also quantify the variation of ambient seismic noise at different depths in the near surface using the geophones in the shallow borehole array.

Artist Concept of InSight Lander on Mars

NASA Image and Video Library

2015-08-18

This artist's concept from August 2015 depicts NASA's InSight Mars lander fully deployed for studying the deep interior of Mars. This illustration updates the correct placement and look of Insight's main instruments. For an earlier artist rendition, see PIA17358. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, will investigate processes that formed and shaped Mars. Its findings will improve understanding about the evolution of our inner solar system's rocky planets, including Earth. The lander will be the first mission to permanently deploy instruments directly onto Martian ground using a robotic arm. The two instruments to be placed into a work area in front of the lander are a seismometer (contributed by the French space agency Centre National d'Études Spatiales, or CNES) to measure the microscopic ground motions from distant marsquakes providing information about the interior structure of Mars, and a heat-flow probe (contributed by the German Aerospace Center, or DLR) designed to hammer itself 3 to 5 meters (about 16 feet) deep and monitor heat coming from the planet's interior. The mission will also track the lander's radio to measure wobbles in the planet's rotation that relate to the size of its core and a suite of environmental sensors to monitor the weather and variations in the magnetic field. Two cameras will aid in instrument deployment and monitoring the local environment. Note: After thorough examination, NASA managers have decided to suspend the planned March 2016 launch of the Interior Exploration using Seismic Investigations Geodesy and Heat Transport (InSight) mission. The decision follows unsuccessful attempts to repair a leak in a section of the prime instrument in the science payload. http://photojournal.jpl.nasa.gov/catalog/PIA19811

Odor-Induced Neuronal Rhythms in the Olfactory Bulb Are Profoundly Modified in ob/ob Obese Mice

PubMed Central

Chelminski, Yan; Magnan, Christophe; Luquet, Serge H.; Everard, Amandine; Meunier, Nicolas; Gurden, Hirac; Martin, Claire

2017-01-01

Leptin, the product of the Ob(Lep) gene, is a peptide hormone that plays a major role in maintaining the balance between food intake and energy expenditure. In the brain, leptin receptors are expressed by hypothalamic cells but also in the olfactory bulb, the first central structure coding for odors, suggesting a precise function of this hormone in odor-evoked activities. Although olfaction plays a key role in feeding behavior, the ability of the olfactory bulb to integrate the energy-related signal leptin is still missing. Therefore, we studied the fate of odor-induced activity in the olfactory bulb in the genetic context of leptin deficiency using the obese ob/ob mice. By means of an odor discrimination task with concomitant local field potential recordings, we showed that ob/ob mice perform better than wild-type (WT) mice in the early stage of the task. This behavioral gain of function was associated in parallel with profound changes in neuronal oscillations in the olfactory bulb. The distribution of the peaks in the gamma frequency range was shifted toward higher frequencies in ob/ob mice compared to WT mice before learning. More notably, beta oscillatory activity, which has been shown previously to be correlated with olfactory discrimination learning, was longer and stronger in expert ob/ob mice after learning. Since oscillations in the olfactory bulb emerge from mitral to granule cell interactions, our results suggest that cellular dynamics in the olfactory bulb are deeply modified in ob/ob mice in the context of olfactory learning. PMID:28154537

Reduction of obesity, as induced by leptin, reverses endothelial dysfunction in obese (Lep(ob)) mice

NASA Technical Reports Server (NTRS)

Winters, B.; Mo, Z.; Brooks-Asplund, E.; Kim, S.; Shoukas, A.; Li, D.; Nyhan, D.; Berkowitz, D. E.

2000-01-01

Obesity is a major health care problem and is associated with significant cardiovascular morbidity. Leptin, a neuroendocrine hormone released by adipose tissue, is important in modulating obesity by signaling satiety and increasing metabolism. Moreover, leptin receptors are expressed on vascular endothelial cells (ECs) and mediate angiogenesis. We hypothesized that leptin may also play an important role in vasoregulation. We investigated vasoregulatory mechanisms in the leptin-deficient obese (ob/ob) mouse model and determined the influence of leptin replacement on endothelial-dependent vasorelaxant responses. The direct effect of leptin on EC nitric oxide (NO) production was also tested by using 4, 5-diaminofluorescein-2 diacetate staining and measurement of nitrate and nitrite concentrations. Vasoconstrictor responses to phenylephrine, norepinephrine, and U-46619 were markedly enhanced in aortic rings from ob/ob mice and were modulated by NO synthase inhibition. Vasorelaxant responses to ACh were markedly attenuated in mesenteric microvessels from ob/ob mice. Leptin replacement resulted in significant weight loss and reversal of the impaired endothelial-dependent vasorelaxant responses observed in ob/ob mice. Preincubation of ECs with leptin enhanced the release of NO production. Thus leptin-deficient ob/ob mice demonstrate marked abnormalities in vasoregulation, including impaired endothelial-dependent vasodilation, which is reversed by leptin replacement. These findings may be partially explained by the direct effect of leptin on endothelial NO production. These vascular abnormalities are similar to those observed in obese, diabetic, leptin-resistant humans. The ob/ob mouse may, therefore, be an excellent new model for the study of the cardiovascular effects of obesity.

iNOS inhibits hair regeneration in obese diabetic (ob/ob) mice.

PubMed

Sasaki, Mari; Shinozaki, Shohei; Morinaga, Hironobu; Kaneki, Masao; Nishimura, Emi; Shimokado, Kentaro

2018-07-02

Previous studies have shown that androgenic alopecia is associated with metabolic syndrome and diabetes. However, the detailed mechanism whereby diabetes causes alopecia still remains unclear. We focused on the inflammatory response that is caused by diabetes or obesity, given that inflammation is a risk factor for hair loss. Inducible nitric oxide synthase (iNOS) is known to be upregulated under conditions of acute or chronic inflammation. To clarify the potential role of iNOS in diabetes-related alopecia, we generated obese diabetic iNOS-deficient (ob/ob; iNOS-KO mice). We observed that ob/ob; iNOS-KO mice were potentiated for the transition from telogen (rest phase) to anagen (growth phase) in the hair cycle compared with iNOS-proficient ob/ob mice. To determine the effect of nitric oxide (NO) on the hair cycle, we administered an iNOS inhibitor intraperitoneally (compound 1400 W, 10 mg/kg) or topically (10% aminoguanidine) in ob/ob mice. We observed that iNOS inhibitors promoted anagen transition in ob/ob mice. Next, we administered an NO donor (S-nitrosoglutathione, GSNO), to test whether NO has the telogen elongation effects. The NO donor was sufficient to induce telogen elongation in wild-type mice. Together, our data indicate that iNOS-derived NO plays a role in telogen elongation under the inflammatory conditions associated with diabetes in mice. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Deficient copper concentrations in dried-defatted hepatic tissue from ob/ob mice: A potential model for study of defective copper regulation in metabolic liver disease.

PubMed

Church, Stephanie J; Begley, Paul; Kureishy, Nina; McHarg, Selina; Bishop, Paul N; Bechtold, David A; Unwin, Richard D; Cooper, Garth J S

2015-05-08

Ob/ob mice provide an animal model for non-alcoholic fatty liver disease/non-alcoholic steatohepatitis (NAFLD/NASH) in patients with obesity and type-2 diabetes. Low liver copper has been linked to hepatic lipid build-up (steatosis) in animals with systemic copper deficiency caused by low-copper diets. However, hepatic copper status in patients with NAFLD or NASH is uncertain, and a validated animal model useful for the study of hepatic copper regulation in common forms of metabolic liver disease is lacking. Here, we report parallel measurements of essential metal levels in whole-liver tissue and defatted-dried liver tissue from ob/ob and non-obese control mice. Measurements in whole-liver tissue from ob/ob mice at an age when they have developed NAFLD/NASH, provide compelling evidence for factitious lowering of copper and all other essential metals by steatosis, and so cannot be used to study hepatic metal regulation in this model. By marked contrast, metal measurements in defatted-dried liver samples reveal that most essential metals were actually normal and indicate specific lowering of copper in ob/ob mice, consistent with hepatic copper deficiency. Thus ob/ob mice can provide a model useful for the study of copper regulation in NAFLD and NASH, provided levels are measured in defatted-dried liver tissue. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Tau hyperphosphorylation in the brain of ob/ob mice is due to hypothermia: Importance of thermoregulation in linking diabetes and Alzheimer's disease.

PubMed

Gratuze, Maud; El Khoury, Noura B; Turgeon, Andréanne; Julien, Carl; Marcouiller, François; Morin, Françoise; Whittington, Robert A; Marette, André; Calon, Frédéric; Planel, Emmanuel

2017-02-01

Over the last few decades, there has been a significant increase in epidemiological studies suggesting that type 2 diabetes (T2DM) is linked to a higher risk of Alzheimer's disease (AD). However, how T2DM affects AD pathology, such as tau hyperphosphorylation, is not well understood. In this study, we investigated the impact of T2DM on tau phosphorylation in ob/ob mice, a spontaneous genetic model of T2DM. Tau phosphorylation at the AT8 epitope was slightly elevated in 4-week-old ob/ob mice while 26-week-old ob/ob mice exhibited tau hyperphosphorylation at multiple tau phospho-epitopes (Tau1, CP13, AT8, AT180, PHF1). We then examined the mechanism of tau hyperphosphorylation and demonstrated that it is mostly due to hypothermia, as ob/ob mice were hypothermic and normothermia restored tau phosphorylation to control levels. As caffeine has been shown to be beneficial for diabetes, obesity and tau phosphorylation, we, therefore, used it as therapeutic treatment. Unexpectedly, chronic caffeine intake exacerbated tau hyperphosphorylation by promoting deeper hypothermia. Our data indicate that tau hyperphosphorylation is predominately due to hypothermia consequent to impaired thermoregulation in ob/ob mice. This study establishes a novel link between diabetes and AD, and reinforces the importance of recording body temperature to better assess the relationship between diabetes and AD. Copyright © 2016 Elsevier Inc. All rights reserved.

Cytochrome P450 (CYP) epoxygenases as potential targets in the management of impaired diabetic wound healing.

PubMed

Zhao, Huichen; Chen, Jicui; Chai, Jiachao; Zhang, Yuchao; Yu, Cong; Pan, Zhe; Gao, Peng; Zong, Chen; Guan, Qingbo; Fu, Yuqin; Liu, Yuantao

2017-07-01

Epoxyeicosatrienoic acids (EETs) are the epoxidation products of arachidonic acid catalyzed by cytochrome P450 (CYP) epoxygenases, which possess multiple biological activities. In the present study, we aimed to explore the role and effects of CYP epoxygenases/EETs in wound healing in ob/ob mice. Full-thickness skin dorsal wounds were made on ob/ob mice and C57BL/6 control mice. The mRNA and protein expression of CYP epoxygenases were determined in granulation tissues of wounds. Effects of EETs on wound healing were evaluated. Inflammation and angiogenesis in wounds were also observed. Compared with C57BL/6 mice, the mRNA and protein expression of CYP2C65 and CYP2J6 in the granulation tissues in ob/ob mice were significantly reduced. 11,12-EET treatment significantly improved wound healing in ob/ob mice, whereas 14,15-EEZE, an EET antagonist, showed the opposite effect. 11,12-EET treatment decreased neutrophil and macrophage infiltration to the wound sites, resulting in reduced production of inflammatory cytokines, decreased MMP-9 expression, and increased collagen accumulation in the granulation tissues of ob/ob mice. In addition, 11,12-EET increased angiogenesis in the granulation tissues of wounds in ob/ob mice. These findings indicate that reduced expression of CYP epoxygenases may contribute to impaired diabetic wound healing, and exogenous EETs may improve diabetic wound healing by modulating inflammation and angiogenesis.

High Temperature, Wireless Seismometer Sensor for Venus

NASA Technical Reports Server (NTRS)

Ponchak, George E.; Scardelletti, Maximilian C.; Taylor, Brandt; Beard, Steve; Meredith, Roger D.; Beheim, Glenn M.; Hunter Gary W.; Kiefer, Walter S.

2012-01-01

Space agency mission plans state the need to measure the seismic activity on Venus. Because of the high temperature on Venus (462? C average surface temperature) and the difficulty in placing and wiring multiple sensors using robots, a high temperature, wireless sensor using a wide bandgap semiconductor is an attractive option. This paper presents the description and proof of concept measurements of a high temperature, wireless seismometer sensor for Venus. A variation in inductance of a coil caused by the movement of an aluminum probe held in the coil and attached to a balanced leaf-spring seismometer causes a variation of 700 Hz in the transmitted signal from the oscillator/sensor system at 426? C. This result indicates that the concept may be used on Venus.

Use of a bubble tiltmeter as a horizontal seismometer

NASA Technical Reports Server (NTRS)

Miller, W. F.; Geller, R. J.; Stein, S.

1978-01-01

A bubble tiltmeter has been used as a horizontal seismometer. With the appropriate filters, the bubble system has good response for displacement over the passband of conventional seismometers (from about 10 Hz to 200 s), and for tilt from about 1 Hz to DC. The accuracy of the response is confirmed by comparing the filtered bubble output to conventional seismic instruments. The agreement between the filtered bubble records and broad band and short period conventional records is extremely good in every case. The small size, broad-band response, and lack of moving parts make the bubble ideal as an instrument for remote environments. In particular, the instrument seems ideal for the ocean bottom, land and marine boreholes and planetary missions.

Corrigendum to "Depth-varying seismogenesis on an oceanic detachment fault at 13°20‧N on the Mid-Atlantic Ridge" [Earth Planet. Sci. Lett. 479 (2017) 60-70

NASA Astrophysics Data System (ADS)

Craig, Timothy J.; Parnell-Turner, Ross

2018-06-01

The microseismic hypocenters plotted in our study, derived in Parnell-Turner et al. (2017), used data collected by instrumentation from the NERC Ocean-Bottom Instrumentation Facility (Minshull et al., 2005) under the auspices of NERC projects NE/J022551/1, NE/J02029X/1 and NE/J021741/1 led by Tim Reston, Christine Peirce and Christopher MacLeod, during cruises JC102 and JC109 led by Christine Peirce. The raw seismic data from the OBS deployment are available from the NERC's British Oceanographic Data Centre (https://www.bodc.ac.uk), or by contacting the NERC grant-holders directly.

Environmental Impact Analysis Process. Deployment Area Selection and Land Withdrawal/Acquisition DEIS. Chapter IV. Part III. Environmental Consequences to the Study Regions and Operating Base Vicinities.

DTIC Science & Technology

1980-12-01

4.4.2-4 Distribution of the larger playa lakes in the Texas high plains. 4-793 4.4.2-5 Distribution of elk in the vicinity of Beryl, Utah, OB. 4-796 4.4.2... lIMA 28DAA SUITABILITY AREAS * 221 Ci~)HYDROLOGIC SUBUNITS 08 SUITABILITY AREAS (2 ARIONA In 22M 2211 212 / 3222-D Table 4.3.2.10-1. Summary of energy...is constructed 4-636 W F’ 130 --- *47 In- IGIA 744 711 soo LPL IS12 13 0 Um ?S ______________ 119 47 lIMA 14PROVO 13 UTN4 SEVE -. 4 t UT "SA 2111 06

The potential effects of Ocimum basilicum on health: a review of pharmacological and toxicological studies.

PubMed

Sestili, Piero; Ismail, Tariq; Calcabrini, Cinzia; Guescini, Michele; Catanzaro, Elena; Turrini, Eleonora; Layla, Anam; Akhtar, Saeed; Fimognari, Carmela

2018-07-01

Basil (Ocimum basilicum L., OB) is a plant world widely used as a spice and a typical ingredient of the healthy Mediterranean diet. In traditional medicine, OB is indicated for many maladies and conditions; OB-containing nutritional supplements are increasingly sold. Conversely, safety concerns have been raised about the promutagens and procarcinogens alkenylbenzenes contained in OB. Areas covered: A critical review of the current status of OB as a nutraceutical, the pharmacology of its bioactive components, the rationale for its indications, and its safety. Expert opinion: Due to the polyphenolic and flavonoidic content, OB can be considered as an important ingredient in healthy diets; OB preparations may be effective as chemopreventive agents or adjunctive therapy in the treatment of different clinical conditions. From a toxicological perspective, since the tumorigenic potential of alkenylbenzenes is counteracted by other OB constituents such as nevadensin, it can be concluded that OB consumption in food and preparations is safe. The only concern relates to OB essential oils: in this case, a concentration limit for alkenylbenzenes should be precautionary defined, and the use of plant chemotypes with no or low levels of these alkylbenzenes for the preparation of essential oils should be made compulsory.

Leptin Increases Striatal Dopamine D2 Receptor Binding in Leptin-Deficient Obese (ob/ob) Mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pfaffly, J.; Michaelides, M.; Wang, G-J.

2010-06-01

Peripheral and central leptin administration have been shown to mediate central dopamine (DA) signaling. Leptin-receptor deficient rodents show decreased DA D2 receptor (D2R) binding in striatum and unique DA profiles compared to controls. Leptin-deficient mice show increased DA activity in reward-related brain regions. The objective of this study was to examine whether basal D2R-binding differences contribute to the phenotypic behaviors of leptin-deficient ob/ob mice, and whether D2R binding is altered in response to peripheral leptin treatment in these mice. Leptin decreased body weight, food intake, and plasma insulin concentration in ob/ob mice but not in wild-type mice. Basal striatal D2Rmore » binding (measured with autoradiography [{sup 3}H] spiperone) did not differ between ob/ob and wild-type mice but the response to leptin did. In wild-type mice, leptin decreased striatal D2R binding, whereas, in ob/ob mice, leptin increased D2R binding. Our findings provide further evidence that leptin modulates D2R expression in striatum and that these effects are genotype/phenotype dependent.« less

The Cygnus OB2 Star Forming Complex

NASA Astrophysics Data System (ADS)

Rybarczyk, Daniel R.; Bania, Thomas

2018-01-01

Almost all astrophysical systems—from planets to stars to supernovae to entire galaxies—are impacted by the process of star formation. The brightest, most massive stars (OB stars) form in hot young clusters called OB associations. Cygnus OB2 is an OB association containing over 160 OB stars, making it one of the largest in the Milky Way Galaxy. At a distance of less than 1.5 kpc, its proximity to the Sun makes it optimal for assessing the process of Galactic star formation and its implications for stellar evolution, Galactic structure, and Galactic chemical evolution. Using existing data sets, we derive comprehensive maps of the distribution of thermal continuum, atomic, and molecular emission from the interstellar gas in Cyg OB2. The thermal continuum emission stems from the plasma ionized by OB stars. The atomic gas is probed by emission from atomic hydrogen, HI, at 21 cm wavelength. The molecular gas is traced by emission from the CO molecule which is a proxy for molecular hydrogen, H2. We combine these atomic and molecular data to derive a map of the total proton column density distribution in Cyg OB2. We also analyze the velocity fields of the OB stars, the atomic and molecular hydrogen gas, and the HII regions' radio recombination emission. As expected, we find HII regions to be spatially coincident with zones of higher cloud density. Surrounding the greatest concentration of OB stars is a cavity in the radio continuum and CO emission. This results from shock waves produced by the combined action of the high HII region pressure and winds from the OB stars. Such a distribution implies that Cyg OB2 is old enough to have evolved to this state.

Ob/ob Mouse Livers Show Decreased Oxidative Phosphorylation Efficiencies and Anaerobic Capacities after Cold Ischemia

PubMed Central

Tagaloa, Sherry; Zhang, Linda; Dare, Anna J.; MacDonald, Julia R.; Yeong, Mee-Ling; Bartlett, Adam S. J. R.; Phillips, Anthony R. J.

2014-01-01

Background Hepatic steatosis is a major risk factor for graft failure in liver transplantation. Hepatic steatosis shows a greater negative influence on graft function following prolonged cold ischaemia. As the impact of steatosis on hepatocyte metabolism during extended cold ischaemia is not well-described, we compared markers of metabolic capacity and mitochondrial function in steatotic and lean livers following clinically relevant durations of cold preservation. Methods Livers from 10-week old leptin-deficient obese (ob/ob, n = 9) and lean C57 mice (n = 9) were preserved in ice-cold University of Wisconsin solution. Liver mitochondrial function was then assessed using high resolution respirometry after 1.5, 3, 5, 8, 12, 16 and 24 hours of storage. Metabolic marker enzymes for anaerobiosis and mitochondrial mass were also measured in conjunction with non-bicarbonate tissue pH buffering capacity. Results Ob/ob and lean mice livers showed severe (>60%) macrovesicular and mild (<30%) microvesicular steatosis on Oil Red O staining, respectively. Ob/ob livers had lower baseline enzymatic complex I activity but similar adenosine triphosphate (ATP) levels compared to lean livers. During cold storage, the respiratory control ratio and complex I-fueled phosphorylation deteriorated approximately twice as fast in ob/ob livers compared to lean livers. Ob/ob livers also demonstrated decreased ATP production capacities at all time-points analyzed compared to lean livers. Ob/ob liver baseline lactate dehydrogenase activities and intrinsic non-bicarbonate buffering capacities were depressed by 60% and 40%, respectively compared to lean livers. Conclusions Steatotic livers have impaired baseline aerobic and anaerobic capacities compared to lean livers, and mitochondrial function indices decrease particularly from after 5 hours of cold preservation. These data provide a mechanistic basis for the clinical recommendation of shorter cold storage durations in steatotic donor livers. PMID:24956382

iPLA2β deficiency attenuates obesity and hepatic steatosis in ob/ob mice through hepatic fatty-acyl phospholipid remodeling.

PubMed

Deng, Xiuling; Wang, Jiliang; Jiao, Li; Utaipan, Tanyarath; Tuma-Kellner, Sabine; Schmitz, Gerd; Liebisch, Gerhard; Stremmel, Wolfgang; Chamulitrat, Walee

2016-05-01

PLA2G6 or GVIA calcium-independent PLA2 (iPLA2β) is identified as one of the NAFLD modifier genes in humans, and thought to be a target for NAFLD therapy. iPLA2β is known to play a house-keeping role in phospholipid metabolism and remodeling. However, its role in NAFLD pathogenesis has not been supported by results obtained from high-fat feeding of iPLA2β-null (PKO) mice. Unlike livers of human NAFLD and genetically obese rodents, fatty liver induced by high-fat diet is not associated with depletion of hepatic phospholipids. We therefore tested whether iPLA2β could regulate obesity and hepatic steatosis in leptin-deficient mice by cross-breeding PKO with ob/ob mice to generate ob/ob-PKO mice. Here we observed an improvement in ob/ob-PKO mice with significant reduction in serum enzymes, lipids, glucose, insulin as well as improved glucose tolerance, and reduction in islet hyperplasia. The improvement in hepatic steatosis measured by liver triglycerides, fatty acids and cholesterol esters was associated with decreased expression of PPARγ and de novo lipogenesis genes, and the reversal of β-oxidation gene expression. Notably, ob/ob livers contained depleted levels of lysophospholipids and phospholipids, and iPLA2β deficiency in ob/ob-PKO livers lowers the former, but replenished the latter particularly phosphatidylethanolamine (PE) and phosphatidylcholine (PC) that contained arachidonic (AA) and docosahexaenoic (DHA) acids. Compared with WT livers, PKO livers also contained increased PE and PC containing AA and DHA. Thus, iPLA2β deficiency protected against obesity and ob/ob fatty liver which was associated with hepatic fatty-acyl phospholipid remodeling. Our results support the deleterious role of iPLA2β in severe obesity associated NAFLD. Copyright © 2016 Elsevier B.V. All rights reserved.

Clinical effect of four different ointment bases on healthy cat eyes.

PubMed

Eördögh, Réka; Schwendenwein, Ilse; Tichy, Alexander; Loncaric, Igor; Nell, Barbara

2016-07-01

To describe the effects of long-term treatment with four different eye ointment bases (OBs) in cats. Ten healthy cats. The study was performed in two periods. Four different OBs were tested. Hundred grams of OB contained the following: OB-A: 35.17 g liquid paraffin (lp), 64.83 g white petrolatum (wp); OB-B: 10.03 g lp, 84.95 g wp 5.02 g lanolin; OB-C: 18.34 g lp, 51.40 g wp, 25.00 mg KH2 PO4 , 57.00 mg K2 HPO4 , 18.90 g eucerinum anhydricum, 11.28 g water for injections; and OB-D: 70 g unguentum lanalcoli, 20 g lp, 10 g aqua conservans. One eye was treated, and the other served as a negative control. Cats received the OBs TID for 28 days. The two study periods were separated by a 4-month washout phase. Samples for conjunctival impression cytology, swabs for bacteriologic and mycologic examination, and cytobrush samples for FHV-1 and Chlamydophila felis PCR detection were obtained. Both eyes were examined daily. Severity of ocular symptoms was scored using a modified Draize eye irritation test. A total of five eyes were treated with OB-A, five with OB-B, four with OB-C, and five with OB-D. Treated eyes had significantly higher clinical scores. Eyes receiving OB-A had the highest overall clinical score. The results of bacteriologic and mycologic examination concur with the previously published data. All samples tested were negative for FHV-1 and Chlamydophila felis. There was no significant difference between treated and control eyes upon cytological examination. The application of OBs resulted in clinical symptoms in treated eyes. The long-term use of ointments is not well tolerated in cats and may lead to ocular irritation. © 2015 American College of Veterinary Ophthalmologists.

[Development of the Human Olfactory Bulbs in the Prenatal Ontogenesis: an Immunochistochemical Study with Markers of Presynaptic Terminals (anti-SNAP-25, -Synapsin-I, -Synaptophysin)].

PubMed

Kharlamova, A S; Barabanov, V M; Saveliev, S V

2015-01-01

We provide the data of the olfactory bulbs (OB) development in the human fetuses on the stages from 8 week to birth. Immunochistochemical markers of presynaptic terminals (anti-SNAP-25, -synapsin-I, -synaptophysin) were used to evaluate the maturation of the OB. Differentiation of the OB layers begins from periphery, which implicitly evidences that growth of the olfactory nerves fibers induses not only anatomical differentiation of the OB, but also differentiation of its functional layers. The sites of the developing glomerulus are revealed using the immunochistochemical prosedure on the stage before distinct glomerulus can be identified with common histological procedure. OB conductive system demonstrates immunoreactivity with the antibodies to the presynaptic proteins on the all stages from 10-11 weeks of fetus development. Four stages of the OB development are described. All functional layers of the OB are mature at the 22-weeks stage. Further differentiation of the OB neuroblasts, including lamina formation of the internal granular leyer, glomerular layer development, OB growth continue after 20-22 weeks stage until 38-40 weeks of the fetus develoment. Patterns of the immunoreactivity with antibodies to SNAP-25, synapsin-I and synaptophysin are completely appropriate to those of adult's OB on the 38-40 weeks of the prenatal development. Complete maturity of the human OB is achived at 38-40 weeks of the prenatal development.

Kinematics of OB-associations in Gaia epoch

NASA Astrophysics Data System (ADS)

Mel'nik, A. M.; Dambis, A. K.

2017-12-01

We use stellar proper motions from the Tycho-Gaia Astrometric Solution (TGAS) catalogue to study the kinematics of OB-associations. The TGAS proper motions of OB-associations generally agree well with the Hipparcos proper motions. The parameters of the Galactic rotation curve obtained with TGAS and Hipparcos proper motions agree within the errors. The average one-dimensional velocity dispersion inside 18 OB-associations with more than 10 TGAS stars is σv = 3.9 km s-1, which is considerably smaller, by a factor of 0.4, than the velocity dispersions derived from Hipparcos data. The effective contribution from orbital motions of binary OB-stars into the velocity dispersion σv inside OB-associations is σb = 1.2 km s-1. The median virial and stellar masses of OB-associations are equal to 7.1 × 105 and 9.0 × 103 M⊙, respectively. Thus, OB-associations must be unbound objects, provided they do not include a lot of dense gas. The median star-formation efficiency is ε = 2.1 per cent. Nearly one-third of stars of OB-associations must lie outside their tidal radius. We found that the Per OB1 and Car OB1 associations are expanding with the expansion started in a small region of 11-27 pc 7-10 Myr ago. The average expansion velocity is 6.3 km s-1.

Broadband measurements of the sources of explosions at Stromboli Volcano, Italy

USGS Publications Warehouse

Chouet, B.; Saccorotti, G.; Dawson, P.; Martini, M.; Scarpa, R.; De Luca, G.; Milana, G.; Cattaneo, M.

1999-01-01

During September-October 1997, 21 three-component broadband seismometers were deployed on Stromboli Volcano at radial distances of 0.3-2.2 km from the active crater to investigate the source mechanisms of Strombolian explosions. In the 2-50 s band, the very-long period (VLP) signals associated with explosions are consistent with two stationary sources repeatedly activated in time. VLP particle motions are essentially linear and analyses of semblance and particle motions are consistent with a source centroid offset 300 m beneath and 300 m northwest of the active vents. Similar VLP waveforms are observed at all 21 stations, indicating that the seismograms are source-dominated. The VLP ground displacement response to each explosion may be qualitatively interpreted as: (1) pressurization of the conduit associated with the ascent of a slug of gas; (2) depressurization of the conduit in response to mass withdrawal during the eruption; and (3) repressurization of the conduit associated with the replenishment of the source with fluid. Copyright 1999 by the American Geophysical Union.

Six components observations of local earthquakes during the 2016 Central Italy seismic sequence

NASA Astrophysics Data System (ADS)

Simonelli, A.; Bernauer, F.; Chow, B.; Braun, T.; Wassermann, J. M.; Igel, H.

2017-12-01

For many years the seismological community has looked for a reliable, sensitive, broadband three-component portable rotational sensor. In this preliminary study, we show the possibility of measuring and extracting relevant seismological information from local earthquakes. We employ portable three-component rotational sensors, insensitive to translations, which operate on optical interferometry principles (Sagnac effect). Multiple sensors recording redundantly add significance to the measurements.During the Central Italy seismic sequence in November 2016, we deployed two portable fiber-optic gyroscopes (BlueSeis3A from iXBlue and LCG demonstrator from LITEF) and a broadband seismometer in Colfiorito, Italy. We present here the six-component observations, with analysis of rotational (three redundant components) and translational (three components) ground motions, generated by earthquakes at local distances. For each seismic event, we compare coherence between rotational sensors and estimate a back azimuth consistent with theoretical values. We also estimate Love and Rayleigh wave phase velocities in the 5 to 10 Hz frequency range.

Lunar Meteoroid Impact Observations and the Flux of Kilogram-Size Meteoroids

NASA Technical Reports Server (NTRS)

Suggs, Rob; Cooke, Bill; Koehler, Heather; Moser, Danielle; Suggs, Ron; Swift, Wes

2010-01-01

Meteor showers dominate the environment in this size range and explain the evening/morning flux asymmetry of 1.5:1. With sufficient numbers of impacts, this technique can help determine the population index for some showers. Measured flux of meteoroids in the 100g to kilograms range is consistent with other observations. We have a fruitful observing program underway which has significantly increased the number of lunar impacts observed. Over 200 impacts have been recorded in about 4 years. This analysis reports on the 115 impacts taken under photometric conditions during the first 3 full years of operation. We plan to continue for the foreseeable future as follows: 1) Run detailed model to try explain the concentration near the trailing limb; 2) Build up statistics to better understand the meteor shower environment; 3) Provide support for robotic seismometers and dust missions; and 4) Deploy near-infrared and visible cameras with dichroic beamsplitter to 0.5m telescope in New Mexico.

Integrating science and education during an international, multi-parametric investigation of volcanic activity at Santiaguito volcano, Guatemala

NASA Astrophysics Data System (ADS)

Lavallée, Yan; Johnson, Jeffrey; Andrews, Benjamin; Wolf, Rudiger; Rose, William; Chigna, Gustavo; Pineda, Armand

2016-04-01

In January 2016, we held the first scientific/educational Workshops on Volcanoes (WoV). The workshop took place at Santiaguito volcano - the most active volcano in Guatemala. 69 international scientists of all ages participated in this intensive, multi-parametric investigation of the volcanic activity, which included the deployment of seismometers, tiltmeters, infrasound microphones and mini-DOAS as well as optical, thermographic, UV and FTIR cameras around the active vent. These instruments recorded volcanic activity in concert over a period of 3 to 9 days. Here we review the research activities and present some of the spectacular observations made through this interdisciplinary efforts. Observations range from high-resolution drone and IR footage of explosions, monitoring of rock falls and quantification of the erupted mass of different gases and ash, as well as morphological changes in the dome caused by recurring explosions (amongst many other volcanic processes). We will discuss the success of such integrative ventures in furthering science frontiers and developing the next generation of geoscientists.

Offset-vertical seismic profiling for marine gas hydrate exploration: Is it a suitable technique? First results from ODP Leg 164

USGS Publications Warehouse

Pecher, I.A.; Holbrook, W.S.; Stephen, R.A.; Hoskins, H.; Lizarralde, D.; Hutchinson, D.R.; Wood, W.T.

1997-01-01

Walkaway vertical seismic profiles were acquired during Ocean Drilling Project (ODP) Leg 164 at the Blake Ridge to investigate seismic properties of hydrate-bearing sediments and the zone of free gas beneath them. An evaluation of compressional (P-) wave arrivals Site 994 indicates P-wave anisotrophy in the sediment column. We identified several shear (S-) wave arrivals in the horizontal components of the geophone array in the borehole and in data recorded with an ocean bottom seismometer deployed at the seafloor. S-waves were converted from P-waves at several depth levels in the sediment column. One of the most prominent conversion points appears to be the bottom simulating reflector (BSR). It is likely that other conversion points are located in the zone of low P-wave reflectivity above the BSR. Modeling suggests that a change of the shear modulus is sufficient to cause significant shear conversion without a significant normal-incidence P-wave reflection.

In Situ Geophysical Exploration by Humans in Mars Analog Environments

NASA Technical Reports Server (NTRS)

Shiro, B. R.; Ferrone, K. L.

2010-01-01

We carried out three geophysical experiments in Mars analog environments in order to better understand the challenges future astronauts will face when conducting similar surveys on Mars or the Moon. The experiments included a passive seismometer deployment and a time-domain electromagnetic survey at the Flashline Mars Arctic Research Station (FMARS) on Devon Island, Canada and a seismic refraction survey in southeastern Utah at the Mars Desert Research Station (MDRS). FMARS is located on the rim of the 23 Ma Haughton Crater in a polar desert environment. MDRS is located in an area with sedimentary plateaus and canyons of Jurassic to Cretaceous age. Both facilities were built by The Mars Society to help develop key knowledge about human Mars exploration. Crews of six spend 2-4 weeks in the habitats and conduct eld research on simulated extravehicular activities (EVAs) wearing mock spacesuits. The work reported here was conducted in July 2009 at FMARS and February 2010 at MDRS.

Upper crustal structure of the Hawaiian Swell from seafloor compliance measurements

NASA Astrophysics Data System (ADS)

Doran, A. K.; Laske, G.

2017-12-01

We present new constraints on elastic properties of the marine sediments and crust surrounding the Hawaiian Islands derived from seafloor compliance measurements. We analyze long-period seismic and pressure data collected during the Plume-Lithosphere Undersea Mantle Experiment [Laske et al, 2009], a deployment consisting of nearly 70 broadband ocean-bottom seismometers with an array aperture of over 1000 kilometers. Our results are supported by previous reflection & refraction studies and by direct sampling of the crust from regional drilling logs. We demonstrate the importance of simultaneously modeling density, compressional velocity, and shear velocity, the former two of which are often ignored during compliance investigations. We find variable sediment thickness and composition across the Hawaiian Swell, with the thickest sediments located within the Hawaiian Moat. Improved resolution of near-surface structure of the Hawaiian Swell is crucially important to improve tomographic images of the underlying lithosphere and asthenosphere and to address outstanding questions regarding the size, source, and location of the hypothesized mantle plume.

New massive members of Cygnus OB2

NASA Astrophysics Data System (ADS)

Berlanas, S. R.; Herrero, A.; Comerón, F.; Pasquali, A.; Motta, C. Bertelli; Sota, A.

2018-04-01

Context. The Cygnus complex is one of the most powerful star forming regions at a close distance from the Sun ( 1.4 kpc). Its richest OB association Cygnus OB2 is known to harbor many tens of O-type stars and hundreds of B-type stars, providing a large homogeneous population of OB stars that can be analyzed. Many studies of its massive population have been developed in the last decades, although the total number of OB stars is still incomplete. Aim. Our aim is to increase the sample of O and B members of Cygnus OB2 and its surroundings by spectroscopically classifying 61 candidates as possible OB-type members of Cygnus OB2, using new intermediate resolution spectroscopy. Methods: We have obtained intermediate resolution (R 5000) spectra for all of the OB-type candidates between 2013 and 2017. We thus performed a spectral classification of the sample using HeI-II and metal lines rates, as well as the Marxist Ghost Buster (MGB) software for O-type stars and the IACOB standards catalog for B-type stars. Results: From the whole sample of 61 candidates, we have classified 42 stars as new massive OB-type stars, earlier than B3, in Cygnus OB2 and surroundings, including 11 O-type stars. The other candidates are discarded as they display later spectral types inconsistent with membership in the association. We have also obtained visual extinctions for all the new confirmed massive OB members, placing them in a Hertzsprung-Russell Diagram using calibrations for Teff and luminosity. Finally, we have studied the age and extinction distribution of our sample within the region. Conclusions: We have obtained new blue intermediate-resolution spectra suitable for spectral classification of 61 OB candidates in Cygnus OB2 and surroundings. The confirmation of 42 new OB massive stars (earlier than B3) in the region allows us to increase the young massive population known in the field. We have also confirmed the correlation between age and Galactic longitude previously found in the region. We conclude that many O and early B stars at B > 16 mag are still undiscovered in Cygnus.

The role of gap junctions in megakaryocyte-mediated osteoblast proliferation and differentiation.

PubMed

Ciovacco, Wendy A; Goldberg, Carolyn G; Taylor, Amanda F; Lemieux, Justin M; Horowitz, Mark C; Donahue, Henry J; Kacena, Melissa A

2009-01-01

Gap junctions (GJs) are membrane-spanning channels that facilitate intercellular communication by allowing small signaling molecules (e.g. calcium ions, inositol phosphates, and cyclic nucleotides) to pass from cell to cell. Over the past two decades, many studies have described a role for GJ intercellular communication (GJIC) in the proliferation and differentiation of many cells, including bone cells. Recently, we reported that megakaryocytes (MKs) enhance osteoblast (OB) proliferation by a juxtacrine signaling mechanism. Here we determine whether this response is facilitated by GJIC. First we demonstrate that MKs express connexin 43 (Cx43), the predominant GJ protein expressed by bone cells, including OBs. Next, we provide data showing that MKs can communicate with OBs via GJIC, and that the addition of two distinct GJ uncouplers, 18alpha-glycyrrhetinic acid (alphaGA) or oleamide, inhibits this communication. We then demonstrate that inhibiting MK-mediated GJIC further enhances the ability of MKs to stimulate OB proliferation. Finally, we show that while culturing MKs with OBs reduces gene expression of several differentiation markers/matrix proteins (type I collagen, osteocalcin, and alkaline phosphatase), reduces alkaline phosphatase enzymatic activity, and decreases mineralization in OBs, blocking GJIC does not result in MK-induced reductions in OB gene expression, enzymatic levels, or mineralized nodule formation. Overall, these data provide evidence that GJIC between MKs and OBs is functional, and that inhibiting GJIC in MK-OB cultures enhances OB proliferation without apparently altering differentiation when compared to similarly treated OB cultures. Thus, these observations regarding MK-OB GJIC inhibition may provide insight regarding potential novel targets for anabolic bone formation.

The Role of Gap Junctions in Megakaryocyte-Mediated Osteoblast Proliferation and Differentiation

PubMed Central

Ciovacco, Wendy A.; Goldberg, Carolyn G.; Taylor, Amanda F.; Lemieux, Justin M.; Horowitz, Mark C.; Donahue, Henry J.; Kacena, Melissa A.

2009-01-01

Gap junctions (GJs) are membrane-spanning channels that facilitate intercellular communication by allowing small signaling molecules (e.g. calcium ions, inositol phosphates, and cyclic nucleotides) to pass from cell to cell. Over the past two decades, many studies have described a role for GJ intercellular communication (GJIC) in the proliferation and differentiation of many cells, including bone cells. Recently, we reported that megakaryocytes (MKs) enhance osteoblast (OB) proliferation by a juxtacrine signaling mechanism. Here we determine whether that response is facilitated by GJIC. First we demonstrate that MKs express connexin 43 (Cx43), the predominant GJ protein expressed by bone cells, including OBs. Next, we provide data showing that MKs can communicate with OBs via GJIC, and that the addition of two distinct GJ uncouplers, 18α-glycyrrhetinic acid (αGA) or oleamide, inhibits this communication. We then demonstrate that inhibiting MK-mediated GJIC further enhances the ability of MK to stimulate OB proliferation. Finally, we show that while culturing MKs with OBs reduces gene expression of several differentiation markers/matrix proteins (type I collagen, osteocalcin, and alkaline phosphatase), reduces alkaline phosphatase enzymatic activity, and decreases mineralization in OBs, blocking GJIC does not result in MK-induced reductions in OB gene expression, enzymatic levels, or mineralized nodule formation. Overall, these data provide evidence that GJIC between MKs and OBs is functional, and that inhibiting GJIC in MK-OB cultures enhances OB proliferation without apparently altering differentiation when compared to similarly treated OB cultures. Thus, these observations regarding MK-OB GJIC inhibition may provide insight regarding potential novel targets for anabolic bone formation. PMID:18848655

Racial and Ethnic Disparities in Cardiovascular Disease: An Assessment of Obstetrician-Gynecologists' Knowledge, Attitudes, and Practice Patterns.

PubMed

Jones, Katherine M; Carter, Michele M; Schulkin, Jay

2015-06-01

African American and Hispanic women are disproportionately affected by cardiovascular disease (CVD) and its many risk factors. Obstetrician-gynecologists (OB/GYNs) play an integral role in well-woman care and have a unique opportunity to provide CVD counseling and screening to these at-risk and underserved groups. To assess whether OB/GYN race/ethnicity and OB/GYN practices with increasing minority patient populations predicted differences in OB/GYNs' knowledge, attitudes, and practice patterns relevant to racial/ethnic disparities in CVD. This study also sought to determine provider and patient-related barriers to CVD care. A questionnaire on CVD was mailed to 273 members of The American College of Obstetricians and Gynecologists in March-July 2013. African American and Hispanic OB/GYNs and OB/GYN practices with increasing minority patient populations were more knowledgeable of CVD disparities. These OB/GYNs reported greater concern for minority women's CVD risk relative to White OB/GYNs. Overall, OB/GYNs appear less knowledgeable and concerned with Hispanics' increased CVD risk relative to African Americans'. The most commonly reported provider and patient-related barriers to CVD care were time constraints, patient nonadherence to treatment recommendations, and inadequate training. It is likely that minority OB/GYNs and those with practices with increasing minority patient populations have greater exposure to women at risk for CVD. Dissemination of educational information regarding Hispanic women's CVD risk profile may improve OB/GYN knowledge, counseling, and screening. Increased training in CVD and multicultural competency during medical school and residency should help OB/GYNs overcome what they report as primary barriers to CVD care.

Overexpression of leptin receptor in human glioblastoma: Correlation with vasculogenic mimicry and poor prognosis

PubMed Central

Yue, Zhijian; Zhang, Yuhui; Wang, Laixing; Liu, Jianmin

2017-01-01

Vasculogenic mimicry (VM) was an important tumor blood supply to complement the endothelial cell-dependent angiogenesis, while leptin and receptor (ObR) involved in angiogenesis in glioblastoma has been reported on previous study, but the relationship between ObR expression and VM formation in human glioblastoma tissues, as well as their prognostic significance still remains unclear. In our study, we found that VM recognized by CD31-/PAS+ immunohistochemical staining in glioblastoma tissues showed a positive correlation with leptin expression (r = 0.58, P < 0.01), as well as ObR expression in glioblastoma tissues (r = 0.61, P < 0.01). Association of glial to mesenchymal transition (GMT)-related molecular with ObR expression and VM formation in glioblastoma tissues indicated that ObR-positive glioblastoma cells with GMT phenotype might be more likely to constitute VM, and co-expression of ObR and CD133 or Nestin to constitute the channel impliated that ObR-positive glioblastoma cells displayed glioblastoma stem cells (GSC) properties. Moreover, Kaplan–Meier statistical analysis showed that patients with more VM or ObR expression displayed poorer prognosis for overall survival times than patients with less expression (VMhigh vs. VMlow: P = 0.033; ObRhigh vs. ObRlow: P = 0.009). And ObR+ glioblastoma cells with GSC characteristic were mostly involved in VM formation, whereas a little part of cells were also related to microvascular density (MVD), which suggested that ObR was an important target for anticancer therapy, so further related studies were needed to improve glioblastoma treatment. PMID:28938545

Overview of SAFOD Phases 1 and 2: Drilling, Sampling and Measurements in the San Andreas Fault Zone at Seismogenic Depth

NASA Astrophysics Data System (ADS)

Zoback, M. D.; Hickman, S.; Ellsworth, W.

2005-12-01

In this talk we provide an overview of on-site drilling, sampling and downhole measurement activities associated with the first two Phases of the San Andreas Fault Observatory at Depth. SAFOD is located at the transition between the creeping and locked sections of the fault, 9 km NW of Parkfield, CA. A 2.1 km deep vertical pilot hole was drilled at the site in 2002. The SAFOD main borehole was drilled vertically to a depth of 1.5 km and then deviated at an average angle of 55° to vertical, passing beneath the surface trace of the San Andreas fault, 1.8 km to the NW at a depth of 3.2 km. Repeating microearthquakes on the San Andreas define the main active fault trace at depth, as well as a secondary active fault about 250 m to the SW (i.e., closer to SAFOD). The hole was rotary drilled, comprehensive cuttings were obtained and a real-time analysis of gases in the drilling mud was carried out. Spot cores were obtained at three depths (at casing set points) in the shallow granite and deeper sedimentary rocks penetrated by the hole, augmented by over fifty side-wall cores. Continuous coring of the San Andreas Fault Zone will be carried out in Phase 3 of the project in the summer of 2007. In addition to sampling mud gas, discrete fluid and gas samples were obtained at several depths for geochemical analysis. Real-time geophysical measurements were made while drilling through most of the San Andreas Fault Zone. A suite of "open hole" geophysical measurements were also made over essentially the entire depth of the hole. Construction of the multi-component SAFOD observatory is well underway, with a seismometer and tiltmeter operating at 1 km depth in the pilot hole and a fiber-optic laser strainmeter cemented behind casing in the main hole. A seismometer deployed at depth in the hole between Phases 1 and 2 detected one of the target earthquakes. A number of surface-to-borehole seismic experiments have been carried out to characterize seismic velocities and structures at depth, including deployment of an 80-level, 240-component seismic array in SAFOD in the spring of 2005. With knowledge of P- and S-wave velocities obtained from the geophysical measurements in conjunction with downhole recordings of the SAFOD target earthquake, it appears that the seismically active main trace of the fault is on the order of 400 m SW of the surface trace, in proximity to several candidate zones of particularly anomalous geophysical properties. Observations of casing deformation to be made over the next several years, as well as monitoring of the microearthquakes using seismometers directly within the fault zone, will pinpoint the exact location of this and other active fault traces prior to continuous coring in Phase 3. As will be elaborated in detail by the presentations of the SAFOD science team at this meeting, the activities carried out as part of Phases 1 and 2 of SAFOD lay the ground work for years of exciting research in earthquake physics, fault-rock geology, rock mechanics and the role of fluids and gases in faulting and earthquake generation.

Teaching Geophysics with a Vertical-Component Seismometer

NASA Astrophysics Data System (ADS)

van Wijk, Kasper; Channel, Ted; Viskupic, Karen; Smith, Martin L.

2013-12-01

Earthquakes are some of the more dramatic expressions of the dynamics of our planet. The sudden release of stress built up slowly by tectonic or volcanic processes often has far-reaching consequences, and can be measured (in classrooms) around the world. This is one reason why designing and building seismometers has been a popular activity, , 2 and why different versions of "Seismometer in Schools" projects thrive in the United States, Australia, and Europe. We present a cheap, robust, and easy-to-build seismometer—called the TC1 —to measure seismic displacements in the vertical direction. Its components are easy to obtain and assemble, yet the resulting instrument is accurate enough to record earthquakes from around the globe. The parts list and building instructions of the TC1 seismometer are freely available online. Alternatively, a complete kit can be purchased for around US300. Assembling the system naturally introduces students to a number of concepts in physics and engineering, while upon completion seismic recordings trigger discussions about the dynamics and internal structure of the Earth. The discussions are fostered by service learning and shared in the network of TC1s called the Z-NET.

Occupant behavior models: A critical review of implementation and representation approaches in building performance simulation programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Tianzhen; Chen, Yixing; Belafi, Zsofia

Occupant behavior (OB) in buildings is a leading factor influencing energy use in buildings. Quantifying this influence requires the integration of OB models with building performance simulation (BPS). This study reviews approaches to representing and implementing OB models in today’s popular BPS programs, and discusses weaknesses and strengths of these approaches and key issues in integrating of OB models with BPS programs. Two of the key findings are: (1) a common data model is needed to standardize the representation of OB models, enabling their flexibility and exchange among BPS programs and user applications; the data model can be implemented usingmore » a standard syntax (e.g., in the form of XML schema), and (2) a modular software implementation of OB models, such as functional mock-up units for co-simulation, adopting the common data model, has advantages in providing a robust and interoperable integration with multiple BPS programs. Such common OB model representation and implementation approaches help standardize the input structures of OB models, enable collaborative development of a shared library of OB models, and allow for rapid and widespread integration of OB models with BPS programs to improve the simulation of occupant behavior and quantification of their impact on building performance.« less

Occupant behavior models: A critical review of implementation and representation approaches in building performance simulation programs

DOE PAGES

Hong, Tianzhen; Chen, Yixing; Belafi, Zsofia; ...

2017-07-27

Occupant behavior (OB) in buildings is a leading factor influencing energy use in buildings. Quantifying this influence requires the integration of OB models with building performance simulation (BPS). This study reviews approaches to representing and implementing OB models in today’s popular BPS programs, and discusses weaknesses and strengths of these approaches and key issues in integrating of OB models with BPS programs. Two of the key findings are: (1) a common data model is needed to standardize the representation of OB models, enabling their flexibility and exchange among BPS programs and user applications; the data model can be implemented usingmore » a standard syntax (e.g., in the form of XML schema), and (2) a modular software implementation of OB models, such as functional mock-up units for co-simulation, adopting the common data model, has advantages in providing a robust and interoperable integration with multiple BPS programs. Such common OB model representation and implementation approaches help standardize the input structures of OB models, enable collaborative development of a shared library of OB models, and allow for rapid and widespread integration of OB models with BPS programs to improve the simulation of occupant behavior and quantification of their impact on building performance.« less

Obtaining changes in calibration-coil to seismometer output constants using sine waves

USGS Publications Warehouse

Ringler, Adam T.; Hutt, Charles R.; Gee, Lind S.; Sandoval, Leo D.; Wilson, David C.

2013-01-01

The midband sensitivity of a broadband seismometer is one of the most commonly used parameters from station metadata. Thus, it is critical for station operators to robustly estimate this quantity with a high degree of accuracy. We develop an in situ method for estimating changes in sensitivity using sine‐wave calibrations, assuming the calibration coil and its drive are stable over time and temperature. This approach has been used in the past for passive instruments (e.g., geophones) but has not been applied, to our knowledge, to derive sensitivities of modern force‐feedback broadband seismometers. We are able to detect changes in sensitivity to well within 1%, and our method is capable of detecting these sensitivity changes using any frequency of sine calibration within the passband of the instrument.

Neutralizing IL-17 Prevents Obliterative Bronchiolitis in Murine Orthotopic Lung Transplantation

PubMed Central

Fan, Lin; Benson, Heather L.; Vittal, Ragini; Mickler, Elizabeth A.; Presson, Robin; Jo Fisher, Amanda; Cummings, Oscar W.; Heidler, Kathleen M.; Keller, Melissa R.; Burlingham, William J.; Wilkes, David S.

2011-01-01

Obliterative bronchiolitis (OB) is the key impediment to the long term survival of lung transplant recipients and the lack of a robust pre-clinical model precludes examining OB immunopathogenesis. In the current study, lungs from C57BL/10 H-2b mice that are MHC compatible, but minor histocompatability antigen incompatible, were transplanted into C57BL/6 mice. Histological features and cytokine profiles of OB were assessed. Moderate rejection (grade A3) developed by day 14, with evidence of OB at that time point. At 21 days, OB was present in 55% of grafts and moderate to severe rejection (Grade A3-A4) was present in all mice. At 28 days, OB was present in 44% of mice and severe rejection (Grade A4) was present in all. IL-17A, but not IL-17F, splenic mRNA transcripts and serum protein levels were increased only in mice that developed OB, whereas IL-10 transcripts and protein were increased only in non-OB mice. Neutralizing IL-17 prevented OB, down regulated acute rejection, and upregulated systemic IL-10. Collectively, these data show that transplantation of minor histoincompatible lungs from C57BL/10 mice into C57BL/6 mice results in a highly reproducible pre-clinical model of OB. In addition, these data indicate that neutralizing IL-17A or augmenting IL-10 could be therapeutic interventions to prevent OB. PMID:21521466

The Overt Behaviour Scale-Self-Report (OBS-SR) for acquired brain injury: exploratory analysis of reliability and validity.

PubMed

Kelly, Glenn; Simpson, Grahame K; Brown, Suzanne; Kremer, Peter; Gillett, Lauren

2017-05-23

The objectives were to test the properties, via a psychometric study, of the Overt Behaviour Scale-Self-Report (OBS-SR), a version of the OBS-Adult Scale developed to provide a client perspective on challenging behaviours after acquired brain injury. Study sample 1 consisted of 37 patients with primary brain tumour (PBT) and a family-member informant. Sample 2 consisted of 34 clients with other acquired brain injury (mixed brain injury, MBI) and a service-provider informant. Participants completed the OBS-SR (at two time points), and the Awareness Questionnaire (AQ) and Mayo Portland Adaptability Inventory-III (MPAI-III) once; informants completed the OBS-Adult and AQ once only. PBT-informant dyads displayed "good" levels of agreement (ICC 2,k  = .74; OBS-SR global index). Although MBI-informant dyads displayed no agreement (ICC 2,k  = .22; OBS-SR global index), the sub-group (17/29) rated by clinicians as having moderate to good levels of awareness displayed "fair" agreement (ICC 2,k  = .58; OBS-SR global index). Convergent/divergent validity was demonstrated by significant correlations between OBS-SR subscales and MPAI-III subscales with behavioural content (coefficients in the range .36 -.61). Scores had good reliability across one week (ICC 2,k  = .69). The OBS-SR took approximately 15 minutes to complete. It was concluded that the OBS-SR demonstrated acceptable reliability and validity, providing a useful resource in understanding clients' perspectives about their behaviour.

HIERARCHICAL ORGANIZATION OF OSTEOBLASTS REVEALS THE SIGNIFICANT ROLE OF CD166 IN HEMATOPOIETIC STEM CELL MAINTANANCE AND FUNCTION

PubMed Central

Chitteti, Brahmananda R.; Cheng, Ying-Hua; Kacena, Melissa A.; Srour, Edward F.

2013-01-01

The role of osteoblasts (OB) in maintaining hematopoietic stem cells (HSC) in their niche is well elucidated, but the exact definition, both phenotypically and hierarchically of OB responsible for these functions is not clearly known. We previously demonstrated that OB maturational status influences HSC function whereby immature OB with high Runx2 expression promote hematopoietic expansion. Here, we show that Activated Leukocyte Cell Adhesion Molecule (ALCAM) or CD166 expression on OB is directly correlated with Runx2 expression and high hematopoiesis enhancing activity (HEA). Fractionation of OB with lineage markers: Sca1, osteopontin (OPN), CD166, CD44, and CD90 revealed that Lin-Sca1-OPN+CD166+ cells (CD166+) and their subpopulations fractionated with CD44 and CD90 expressed high levels of Runx2 and low levels of osteocalcin (OC) demonstrating the relatively immature status of these cells. Conversely, the majority of the Lin-Sca1-OPN+CD166− cells (CD166−) expressed high OC levels suggesting that CD166− OB are more mature. In vitro hematopoietic potential of LSK cells co-cultured for 7 days with fresh OB or OB pre-cultured for 1, 2, or 3 weeks declined precipitously with increasing culture duration concomitant with loss of CD166 expression. Importantly, LSK cells co-cultured with CD166+CD44+CD90+ OB maintained their in vivo repopulating potential through primary and secondary transplantation, suggesting that robust HEA activity is best mediated by immature CD166+ OB with high Runx2 and low OC expression. These studies begin to define the hierarchical organization of osteoblastic cells and provide a more refined definition of OB that can mediate HEA. PMID:23369988

Reduced inflammatory response and increased microcirculatory disturbances during hepatic ischemia-reperfusion injury in steatotic livers of ob/ob mice

PubMed Central

Hasegawa, Tadashi; Ito, Yoshiya; Wijeweera, Jayanthika; Liu, Jie; Malle, Ernst; Farhood, Anwar; McCuskey, Robert S.; Jaeschke, Hartmut

2016-01-01

Steatosis is a major risk factor for complications after liver surgery. Since neutrophil cytotoxicity is critical for ischemia-reperfusion injury in normal livers, the aim of the present study was to evaluate whether an exaggerated inflammatory response could cause the increased injury in steatotic livers. In C57Bl/6 mice, 60 min of warm hepatic ischemia triggered a gradual increase in hepatic neutrophil accumulation during reperfusion with peak levels of 100-fold over baseline at 12 h of reperfusion. Neutrophil extravasation and a specific neutrophil-induced oxidant stress (immunostaining for hypochlorous acid-modified epitopes) started at 6 h of reperfusion and peaked at 12–24 h. Ob/ob mice, which had a severe macrovesicular steatosis, suffered significantly higher injury (alanine transaminase activity: 18,000 ± 2,100 U/l; 65% necrosis) compared with lean littermates (alanine transaminase activity: 4,900 ± 720 U/l; 24% necrosis) at 6 h of reperfusion. However, 62% fewer neutrophils accumulated in steatotic livers. This correlated with an attenuated increase in mRNA levels of several proinflammatory genes in ob/ob mice during reperfusion. In contrast, sham-operated ob/ob mice had a 50% reduction in liver blood flow and 35% fewer functional sinusoids compared with lean littermates. These deficiencies in liver blood flow and the microcirculation were further aggravated only in ob/ob mice during reperfusion. The attenuated inflammatory response and reduced neutrophil-induced oxidant stress observed in steatotic livers during reperfusion cannot be responsible for the dramatically increased injury in ob/ob mice. In contrast, the aggravated injury appears to be mediated by ischemic necrosis due to massive impairment of blood and oxygen supply in the steatotic livers. PMID:17307725

Plasma lipoproteins and the synthesis and turnover of plasma triglyceride in normal and genetically obese mice

PubMed Central

Salmon, D. Michael W.; Hems, Douglas A.

1973-01-01

1. Lipoproteins in the plasma of mice were characterized by agarose-gel chromatography and polyacrylamide-gel electrophoresis: genetically obese (ob/ob) mice exhibited hyperlipoproteinaemia (compared with lean mice), largely owing to an increase in the concentration of cholesterol in high-density lipoprotein. Plasma concentrations of triglyceride and phospholipid were not markedly increased in genetically obese mice. 2. The formation of glycerolipids in liver and plasma was investigated with 14C-labelled precursors. The synthesis of hepatic triglyceride and phospholipid from glucose or palmitate was enhanced in ob/ob mice, compared with lean mice. The rate of entry of triglyceride into plasma, calculated from the time-course of incorporation of 14C from [14C]palmitate into plasma triglyceride, was increased in ob/ob mice (0.5μmol of fatty acid/min, compared with 0.2 in lean mice). 3. The removal from plasma of murine lipoprotein triglyceride-[14C]fatty acid was increased in ob/ob mice (half-time 2.2min, compared with 7.2min in lean mice). Similar results were obtained with an injected lipid emulsion (Intralipid). 4. From these measurements, estimates of the rates of turnover of plasma triglyceride in mice (fed on a mixed diet, female, 3 months old) are about 1.0μmol of fatty acid/min in ob/ob mice, and 0.25 in lean mice. 5. The major precursor of hepatic and plasma triglyceride in lean and ob/ob mice was calculated to be plasma free fatty acid. 6. These results are discussed, in connexion with the role of the liver in triglyceride metabolism in mice, especially in relation to genetic obesity. PMID:4360712

Norepinephrine regulates hepatic innate immune system in leptin-deficient mice with nonalcoholic steatohepatitis.

PubMed

Li, Zhiping; Oben, Jude A; Yang, Shiqi; Lin, Huizhi; Stafford, Elizabeth A; Soloski, Mark J; Thomas, Steven A; Diehl, Anna Mae

2004-08-01

It is not known why natural killer T (NKT) cells, which modulate liver injury by regulating local cytokine production, are reduced in leptin-deficient ob/ob mice. NKT cells express adrenoceptors. Thus, we hypothesize that the low norepinephrine (NE) activity of ob/ob mice promotes depletion of liver NKT cells, thereby sensitizing ob/ob livers to lipopolysaccharide (LPS) toxicity. To evaluate this hypothesis, hepatic NKT cells were quantified in wild-type mice before and after treatment with NE inhibitors, and in dopamine beta-hydroxylase knockout mice (which cannot synthesize NE) and ob/ob mice before and after 4 weeks of NE supplementation. Decreasing NE activity consistently reduces liver NKT cells, while increasing NE has the opposite effect. Analysis of hepatic and thymic NKT cells in mice of different ages demonstrate an age-related accumulation of hepatic NKT cells in normal mice, while liver NKT cells become depleted after birth in ob/ob mice, which have increased apoptosis of hepatic NKT cells. NE treatment inhibits apoptosis and restores hepatic NKT cells. In ob/ob mice with reduced hepatic NKT cells, hepatic T and NKT cells produce excessive T helper (Th)-1 proinflammatory cytokines and the liver is sensitized to LPS toxicity. NE treatment decreases Th-1 cytokines, increases production of Th-2 cytokines, and reduces hepatotoxicity. Studies of CD1d-deficient mice, which lack the receptor required for NKT cell development, demonstrate that they are also unusually sensitive to LPS hepatotoxicity. In conclusion, low NE activity increases hepatic NKT cell apoptosis and depletes liver NKT cells, promoting proinflammatory polarization of hepatic cytokine production that sensitizes the liver to LPS toxicity. Copyright 2004 American Association for the Study of Liver Diseases

Sucrose diet induced enzymatic and hormonal responses affecting carbohydrate, lipid and energy metabolism in two species differing in insulin availability: spiny and ob/ob mice.

PubMed

Shafrir, E; Trostler, N

1984-01-01

The low-insulin responding spiny mice (Acomys cahirinus), maintained on a 50% sucrose diet vs isocaloric regular diet, responded with an impressive increase in the activity of hepatic enzymes of glycolysis and lipogenesis and in hyperlipidemia. There was no hyperinsulinemia or hyperglycemia and spiny mice did not gain weight on sucrose due to loss of adipose tissue. Serum T3 levels rose 1.8 fold and the activity of the hepatic mitochondrial FAD-glycerol-3-phosphate oxidase became induced 2.6 fold representing the enhancement of multiple, T3-dependent, energy-consuming metabolic cycles. An increased TG lipolysis in adipose tissue was also observed. C57BL/6J ob/ob mice were markedly hyperinsulinemic and gained weight on sucrose almost as much as those on regular diet, without changes in serum glucose or insulin. Serum triglyceride level decreased, whereas liver triglycerides accumulated markedly. The extent of the increase in hepatic enzyme activities related to lipogenesis was much lower both in the ob/ob mice and their lean siblings, than in spiny mice, but the basal enzyme activities in ob/ob mice were remarkably elevated. Serum T3 level was also elevated already on the regular diet and rose only slightly on sucrose. Basal glycerol phosphate oxidase activity in ob/ob mice exceeded that in spiny mice and rose only marginally on sucrose. Adipose tissue lipolysis was not increased. Thus, sucrose diet by enhancing the T3 production appeared to activate protective mechanism against weight gain in normoinsulinemic spiny mice, whereas the full expression of these mechanisms appeared to be precluded by the hyperinsulinemia of ob/ob mice.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo evidence for unidentified leptin-induced circulating factors that control white fat mass.

PubMed

Harris, Ruth B S

2015-12-15

Fat transplants increase body fat mass without changing the energy status of an animal and provide a tool for investigating control of total body fat. Early transplant studies found that small pieces of transplanted fat took on the morphology of the transplant recipient. Experiments described here tested whether this response was dependent upon expression of leptin receptors in either transplanted fat or the recipient mouse. Fat from leptin receptor deficient db/db mice or wild-type mice was placed subcutaneously in db/db mice. After 12 wk, cell size distribution in the transplant was the same as in endogenous fat of the recipient. Thus, wild-type fat cells, which express leptin receptors, were enlarged in a hyperleptinemic environment, indicating that leptin does not directly control adipocyte size. By contrast, db/db or wild-type fat transplanted into wild-type mice decreased in size, suggesting that a functional leptin system in the recipient is required for body fat mass to be controlled. In the final experiment, wild-type fat was transplanted into a db/db mouse parabiosed to either another db/db mouse to an ob/ob mouse or in control pairs in which both parabionts were ob/ob mice. Transplants increased in size in db/db-db/db pairs, decreased in db/db-ob/ob pairs and did not change in ob/ob-ob/ob pairs. We propose that leptin from db/db parabionts activated leptin receptors in their ob/ob partners. This, in turn, stimulated release of unidentified circulating factors, which travelled back to the db/db partner and acted on the transplant to reduce fat cell size. Copyright © 2015 the American Physiological Society.

Leptin and leucine synergistically regulate protein metabolism in C2C12 myotubes and mouse skeletal muscles.

PubMed

Mao, Xiangbing; Zeng, Xiangfang; Huang, Zhimin; Wang, Junjun; Qiao, Shiyan

2013-07-28

Leucine and leptin play important roles in regulating protein synthesis and degradation in skeletal muscles in vitro and in vivo. However, the objective of the present study was to determine whether leptin and leucine function synergistically in regulating protein metabolism of skeletal muscles. In the in vitro experiment, C2C12 myotubes were cultured for 2 h in the presence of 5 mm-leucine and/or 50 ng/ml of leptin. In the in vivo experiment, C57BL/6 and ob/ob mice were randomly assigned to be fed a non-purified diet supplemented with 3 % L-leucine or 2·04 % L-alanine (isonitrogenous control) for 14 d. Ob/ob mice were injected intraperitoneally with sterile PBS or recombinant mouse leptin (0·1 μg/g body weight) for 14 d. In C57BL/6 mice, dietary leucine supplementation increased (P< 0·05) plasma leptin, leptin receptor expression and protein synthesis in skeletal muscles, but reduced (P< 0·05) plasma urea and protein degradation in skeletal muscles. Dietary leucine supplementation and leptin injection increased the relative weight of the gastrocnemius and soleus muscles in ob/ob mice. Moreover, leucine and leptin treatments stimulated (P< 0·05) protein synthesis and inhibited (P< 0·05) protein degradation in C2C12 myotubes and skeletal muscles of ob/ob mice. There were interactions (P< 0·05) between the leucine and leptin treatments with regard to protein metabolism in C2C12 myotubes and soleus muscles of ob/ob mice but not in the gastrocnemius muscles of ob/ob mice. Collectively, these results suggest that leptin and leucine synergistically regulate protein metabolism in skeletal muscles both in vitro and in vivo.

Diversity in olfactory bulb size in birds reflects allometry, ecology, and phylogeny

PubMed Central

Corfield, Jeremy R.; Price, Kasandra; Iwaniuk, Andrew N.; Gutierrez-Ibañez, Cristian; Birkhead, Tim; Wylie, Douglas R.

2015-01-01

The relative size of olfactory bulbs (OBs) is correlated with olfactory capabilities across vertebrates and is widely used to assess the relative importance of olfaction to a species’ ecology. In birds, variations in the relative size of OBs are correlated with some behaviors; however, the factors that have led to the high level of diversity seen in OB sizes across birds are still not well understood. In this study, we use the relative size of OBs as a neuroanatomical proxy for olfactory capabilities in 135 species of birds, representing 21 orders. We examine the scaling of OBs with brain size across avian orders, determine likely ancestral states and test for correlations between OB sizes and habitat, ecology, and behavior. The size of avian OBs varied with the size of the brain and this allometric relationship was for the most part isometric, although species did deviate from this trend. Large OBs were characteristic of more basal species and in more recently derived species the OBs were small. Living and foraging in a semi-aquatic environment was the strongest variable driving the evolution of large OBs in birds; olfaction may provide cues for navigation and foraging in this otherwise featureless environment. Some of the diversity in OB sizes was also undoubtedly due to differences in migratory behavior, foraging strategies and social structure. In summary, relative OB size in birds reflect allometry, phylogeny and behavior in ways that parallel that of other vertebrate classes. This provides comparative evidence that supports recent experimental studies into avian olfaction and suggests that olfaction is an important sensory modality for all avian species. PMID:26283931

Biphasic positive effect of formononetin on metabolic activity of human normal and osteoarthritic subchondral osteoblasts.

PubMed

Huh, Jeong-Eun; Seo, Dong-Min; Baek, Yong-Hyeon; Choi, Do-Young; Park, Dong-Suk; Lee, Jae-Dong

2010-04-01

Osteoarthritis is a multifactorial disease characterized by loss of articular cartilage and subchondral plate thickening. Therefore, biochemical analysis of the underlying bone tissue has provided important information for treatment of osteoarthritis. In this study, we determined the potential role of formononetin, a phytoestrogen isolated from Astragalus membranaceus to alter the expression of metabolic markers and cytokine production of human normal osteoblasts (Obs) and osteoarthritis subchondral osteoblasts (OA Obs). Human OA Obs and normal Obs were cultured for 3days, 7days or 14days in the present medium only or were treated with various doses of formononetin. Cells were analyzed for viability by WST-8 assay, alkaline phosphatase (ALP) activity, osteogenic markers (osteocalcin (OCN) and type I collagen (Col I)) and cytokines (interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), bone morphogenic protein-2 (BMP-2)). The level of IL-6, VEGF, BMP-2, OCN and Col I was increased in OA Obs compared with normal Obs. Formononetin dose-dependently decreased ALP, IL-6, VEGF, BMP-2, OCN and Col I in OA Obs, while markedly increased ALP, VEGF, BMP-2, OCN and Col I in normal Obs. Interestingly, formononetin markedly increased the expression of VEGF and BMP-2 for 3days of culture and significantly increased OCN and Col I at 14days in human normal Obs. The remodeling effect of formononetin on osteogenic markers and cytokines of inflammatory mediators was more striking in OA Obs as well. Taken together, these results could suggest that formononetin has biphasic positive effects on normal Obs and OA Obs by modifying their biological synthetic capacities. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

Seismic velocity structure of the incoming Pacific Plate subducting into the central part of the Japan Trench revealed by traveltime tomography using OBS data

NASA Astrophysics Data System (ADS)

Obana, K.; Fujie, G.; Kodaira, S.; Takahashi, T.; Yamamoto, Y.; Miura, S.; Shinohara, M.

2016-12-01

Subduction of oceanic plates plays an important role in the water transportation from the earth surface into the deep mantle. Recent active seismic survey studies succeed to image that the seismic velocities within the oceanic crust and the uppermost mantle in the outer rise region decreases toward the trench axis. These velocity changes are considered as an indication of the hydration and alteration of the incoming oceanic plates prior to the subduction. However, the area with sufficient resolution of the active seismic studies is often limited at depths corresponding to the oceanic crust and several km beneath the oceanic Moho. In this study, we have examined the seismic velocity structure of the incoming/subducting Pacific Plate beneath the trench axis and outer trench-slope of the central part of the Japan Trench. The seismicity in the Pacific Plate, including several M7-class intra-plate earthquakes, has been active since the 2011 Tohoku-Oki earthquake in the study area. These activities were observed by the ocean bottom seismographs (OBS) deployed repeatedly. The data obtained from these OBS observations allow us to resolve the seismic velocity structures at greater depths compared to the active seismic surveys. We conducted 3-D traveltime tomography by using double-difference tomography method (Zhang and Thurber, 2003). The results show that the seismic velocities within the oceanic mantle decreased toward the trench axis. The velocity reduction begins at about 80 km seaward of the trench axis and extended to a depth of at least 30 km beneath the trench axis area. If the observed P-wave velocity reduction from 8.4 km/s to 7.7 km/s at a depth of 15 km below the oceanic Moho is caused by the serpentinization of the oceanic mantle (Carlson and Miller, 2003), roughly 2.5 weight per cent of water is expected in the low velocity anomalies in the oceanic mantle.

Holographic otoscope for nanodisplacement measurements of surfaces under dynamic excitation.

PubMed

Flores-Moreno, J M; Furlong, Cosme; Rosowski, John J; Harrington, Ellery; Cheng, Jeffrey T; Scarpino, C; Santoyo, F Mendoza

2011-01-01

We describe a novel holographic otoscope system for measuring nanodisplacements of objects subjected to dynamic excitation. Such measurements are necessary to quantify the mechanical deformation of surfaces in mechanics, acoustics, electronics, biology, and many other fields. In particular, we are interested in measuring the sound-induced motion of biological samples, such as an eardrum. Our holographic otoscope system consists of laser illumination delivery (IS), optical head (OH), and image processing computer (IP) systems. The IS delivers the object beam (OB) and the reference beam (RB) to the OH. The backscattered light coming from the object illuminated by the OB interferes with the RB at the camera sensor plane to be digitally recorded as a hologram. The hologram is processed by the IP using the Fresnel numerical reconstruction algorithm, where the focal plane can be selected freely. Our holographic otoscope system is currently deployed in a clinic, and is packaged in a custom design. It is mounted in a mechatronic positioning system to increase its maneuverability degrees to be conveniently positioned in front of the object to be measured. We present representative results highlighting the versatility of our system to measure deformations of complex elastic surfaces in the wavelength scale including a copper foil membrane and postmortem tympanic membrane. SCANNING 33: 342-352, 2011. © 2011 Wiley Periodicals, Inc. Copyright © 2011 Wiley Periodicals, Inc.

Large-scale magnetic topologies of mid M dwarfs

NASA Astrophysics Data System (ADS)

Morin, J.; Donati, J.-F.; Petit, P.; Delfosse, X.; Forveille, T.; Albert, L.; Aurière, M.; Cabanac, R.; Dintrans, B.; Fares, R.; Gastine, T.; Jardine, M. M.; Lignières, F.; Paletou, F.; Ramirez Velez, J. C.; Théado, S.

2008-10-01

We present in this paper, the first results of a spectropolarimetric analysis of a small sample (~20) of active stars ranging from spectral type M0 to M8, which are either fully convective or possess a very small radiative core. This study aims at providing new constraints on dynamo processes in fully convective stars. This paper focuses on five stars of spectral type ~M4, i.e. with masses close to the full convection threshold (~=0.35Msolar), and with short rotational periods. Tomographic imaging techniques allow us to reconstruct the surface magnetic topologies from the rotationally modulated time-series of circularly polarized profiles. We find that all stars host mainly axisymmetric large-scale poloidal fields. Three stars were observed at two different epochs separated by ~1 yr; we find the magnetic topologies to be globally stable on this time-scale. We also provide an accurate estimation of the rotational period of all stars, thus allowing us to start studying how rotation impacts the large-scale magnetic field. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) and the Télescope Bernard Lyot (TBL). CFHT is operated by the National Research Council of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique of France (INSU/CNRS) and the University of Hawaii, while the TBL is operated by CNRS/INSU. E-mail: jmorin@ast.obs-mip.fr (JM); donati@ast.obs-mip.fr (J-FD); petit@ast.obs-mip.fr (PP); xavier.delfosse@obs.ujf-grenoble.fr (XD); thierry.forveille@obs.ujf-grenoble.fr (TF); albert@cfht.hawaii.edu (LA); auriere@ast.obs-mip.fr (MA); remi.cabanac@ast.obs-mip.fr (RC); dintrans@ast.obs-mip.fr (BD); rfares@ast.obs-mip.fr (RF); tgastine@ast.obs-mip.fr (TG); mmj@st-andrews.ac.uk (MMJ); ligniere@ast.obs-mip.fr (FL); fpaletou@ast.obs-mip.fr (FP); jramirez@mesiog.obspm.fr (JR); sylvie.theado@ast.obs-mip.fr (ST)

Oral delivery of [D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3, synthetic peptide leptin mimetics: Immunofluorescent localization in the mouse hypothalamus.

PubMed

Anderson, Brian M; Jacobson, Lauren; Novakovic, Zachary M; Grasso, Patricia

2017-06-01

This study describes the localization of [D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3, synthetic peptide leptin mimetics, in the hypothalamus of Swiss Webster and C57BL/6J wild-type mice, leptin-deficient ob/ob mice, and leptin-resistant diet-induced obese (DIO) mice. The mice were given [D-Leu-4]-OB3 or MA-[D-Leu-4]-OB3 in 0.3% dodecyl maltoside by oral gavage. Once peak serum concentrations were reached, the mice received a lethal dose of pentobarbital and were subjected to intracardiac perfusion fixation. The brains were excised, post-fixed in paraformaldehyde, and cryo-protected in sucrose. Free-floating frozen coronal sections were cut at 25-µm and processed for imaging by immunofluorescence microscopy. In all four strains of mice, dense staining was concentrated in the area of the median eminence, at the base and/or along the inner wall of the third ventricle, and in the brain parenchyma at the level of the arcuate nucleus. These results indicate that [D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3 cross the blood-brain barrier and concentrate in an area of the hypothalamus known to regulate energy balance and glucose homeostasis. Most noteworthy is the localization of [D-Leu-4]-OB3 immunoreactivity within the hypothalamus of DIO mice via a conduit that is closed to leptin in this rodent model, and in most cases of human obesity. Together with our previous studies describing the effects of [D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3 on energy balance, glucose regulation, and signal transduction pathway activation, these findings are consistent with a central mechanism of action for these synthetic peptide leptin mimetics, and suggest their potential usefulness in the management of leptin-resistant obesity and type 2 diabetes in humans. Copyright © 2017 Elsevier B.V. All rights reserved.

Olfactory bulb volume in Taiwanese patients with posttraumatic anosmia.

PubMed

Jiang, Rong-San; Chai, Jyh-Wen; Chen, Wen-Hsien; Fuh, Wen-Bin; Chiang, Chin-Ming; Chen, Clayton Chi-Chang

2009-01-01

Olfactory bulb (OB) volume has been shown to be an indicator of olfactory function. However, few studies have been done in Asia to investigate the influence of different disorders on OB volume. Data from patients with posttraumatic anosmia were collected in our department. Their olfactory thresholds were assessed by the phenyl ethyl alcohol threshold test. They were treated with a course of high-dose steroid, and followed up for at least 3 months without any olfactory improvement. Magnetic resonance imaging was subsequently used to measure patients' OB volumes. Subjects who self-reported their olfactory function was normal were also included in the control group for comparison. Fifty-four patients with posttraumatic anosmia and 30 subjects who self-reported their olfactory function was normal were enrolled in this study. The mean right OB volume was 45.2 mm3, and the mean left OB volume was 46.3 mm3 in patients with posttraumatic anosmia. The mean right OB volume was 59.7 mm3, and the mean left OB volume was 66.0 mm3 in control subjects. The OB volumes were significantly lower in patients with posttraumatic anosmia. OB volumes were significantly lower in Taiwanese patients with posttraumatic anosmia.

Leptin produced by obese adipose stromal/stem cells enhances proliferation and metastasis of estrogen receptor positive breast cancers.

PubMed

Strong, Amy L; Ohlstein, Jason F; Biagas, Brandi A; Rhodes, Lyndsay V; Pei, Dorothy T; Tucker, H Alan; Llamas, Claire; Bowles, Annie C; Dutreil, Maria F; Zhang, Shijia; Gimble, Jeffrey M; Burow, Matthew E; Bunnell, Bruce A

2015-08-19

The steady increase in the incidence of obesity among adults has been paralleled with higher levels of obesity-associated breast cancer. While recent studies have suggested that adipose stromal/stem cells (ASCs) isolated from obese women enhance tumorigenicity, the mechanism(s) by which this occurs remains undefined. Evidence suggests that increased adiposity results in increased leptin secretion from adipose tissue, which has been shown to increased cancer cell proliferation. Previously, our group demonstrated that ASCs isolated from obese women (obASCs) also express higher levels of leptin relative to ASCs isolated from lean women (lnASCs) and that this obASC-derived leptin may account for enhanced breast cancer cell growth. The current study investigates the impact of inhibiting leptin expression in lnASCs and obASCs on breast cancer cell (BCC) growth and progression. Estrogen receptor positive (ER+) BCCs were co-cultured with leptin shRNA lnASCs or leptin shRNA obASCs and changes in the proliferation, migration, invasion, and gene expression of BCCs were investigated. To assess the direct impact of leptin inhibition in obASCs on BCC proliferation, MCF7 cells were injected alone or mixed with control shRNA obASCs or leptin shRNA obASCs into SCID/beige mice. ER+ BCCs were responsive to obASCs during direct co-culture, whereas lnASCs were unable to increase ER(+) BCC growth. shRNA silencing of leptin in obASCs negated the enhanced proliferative effects of obASC on BCCs following direct co-culture. BCCs co-cultured with obASCs demonstrated enhanced expression of epithelial-to-mesenchymal transition (EMT) and metastasis genes (SERPINE1, MMP-2, and IL-6), while BCCs co-cultured with leptin shRNA obASCs did not display similar levels of gene induction. Knockdown of leptin significantly reduced tumor volume and decreased the number of metastatic lesions to the lung and liver. These results correlated with reduced expression of both SERPINE1 and MMP-2 in tumors formed with MCF7 cells mixed with leptin shRNA obASCs, when compared to tumors formed with MCF7 cells mixed with control shRNA obASCs. This study provides mechanistic insight as to how obesity enhances the proliferation and metastasis of breast cancer cells; specifically, obASC-derived leptin contributes to the aggressiveness of breast cancer in obese women.

The GEMS-2 SEIS Experiment

NASA Astrophysics Data System (ADS)

Tillier, S.; De Raucourt, S.; Mimoun, D.; Lognonne, P.; Giardini, D.; Christensen, U. R.; Pike, W. T.; Banerdt, B.; Laudet, P.; Kerjean, L.; Hurst, K. J.; Zweifel, P.; Mance, D.; Roll, R.; Bierwirth, M.; Gagnepain-Beyneix, J.; Nibut, T.; Robert, O.; Gabsi, T.; Pot, O.; Lecomte, B.; Schibler, P.; Mocquet, A.; Garcia, R.

2011-12-01

The SEIS experiment is the primary payload of the Geophysical Monitoring Station (GEMS) Mission Proposal, submitted to NASA in the frame of the 2010 Discovery program, and recently selected for the phase A study. The objective of the GEMS SEIS experiment is the determination of the deep internal structure of Mars. In particular, geophysical parameters of first importance, such as the state (liquid/solid) and size of the core, as well as structure of the mantle and shape of discontinuities will be determined by the experiment. It will measure seismic activity in a very broad band of signal, from the tidal frequencies (0.05 mHz) up to the short period frequencies (50 Hz), to address the widest range of scientific questions, from the state of the inner core to the meteoritic rate measurement. Infrasound, which might be associated to dust devils and atmospheric discharge, will be also monitored. The instrument integrates a Very Broad Band (VBB) 3 axis seismometer, completed by another trihedron of MEMS short period seismometers, environmental sensors for pressure, wind and temperature, and an infrasound sensor is additionally considered. The sensors will be deployed on the Martian ground by a robotic arm from the Phoenix lander platform and protected by a wind and thermal shield. The sensor assembly, which contains all seismic sensors, the leveling system, as well as house-keeping and temperature measurements, will be deployed on the soil in order to allow the best possible mechanical coupling with the ground motion. Thanks to the wind and thermal shield, together with the sensors' specific containers (vacuum sphere for VBBs), long term VBB bias will be protected from both temperature and pressure variations (as well as passively compensated), allowing the sensor to operate in the rough Martian thermal environment. A dedicated electronics will manage the overall experiment and ultra-low noise, space qualified 24 bits A/D converters will perform the acquisition. The overall mass of the SEIS instrument is about 9.6 kg, including all sensors, data control processors and installation devices, while power consumption is not exceeding 2W. The proposed instrument has been developed up to PDR in the frame of the ExoMars Humbold payload, and further developments were achieved in the frame of the Japanese SELENE2 project. Most critical parts have been tested, including shock tests for pivots, electronics components and displacement sensors. TRL 6 is expected at the end of 2011. The GEMS phase A will end by March 2012, and the final NASA continuation decision is due in June 2012. GEMS is planned to be launched in 2016.

Proposed Construction of Boulder Seismic Station Monitoring Sites, Boulder, Wyoming. Environmental Assessment

DTIC Science & Technology

2009-02-01

power battery box and controllers, WiFi radio, network switch, vault seismometers, infrasonic digitizers, and excess cabling. In addition to the...installed around the boreholes. Immediately upon completion, each site will be cleared of all unused equipment, debris, materials, and trash . All...controllers, WiFi radio, network switch, vault seismometers, infrasonic digitizers, and excess cabling. In addition to the permanent infrastructure listed

The Wireless Data Acquisition System for the Vibration Table

NASA Astrophysics Data System (ADS)

Teng, Y. T.; Hu, X.

2014-12-01

The vibration table is a large-scaled tool used for inspecting the performance of seismometers. The output from a seismometer on the table can be directly monitored when the vibration table moves in certain pattern. Compared with other inspection methods, inspecting seismometers' performance indicators (frequency response, degree of linearity, sensitivity, lateral inhibition and dynamic range etc). using vibration tables is more intuitive. Therefore, the vibration tables are an essential testing part in developing new seismometers and seismometer quality control. Whereas, in practice, a cable is needed to connect the seismometer to the ground equipments for its signal outputs and power supply, that means adding a time-varying nonlinear spring between the vibration table and ground. The cable adds nonlinear feature to the table, distorts the table-board movement and bring extra errors to the inspecting work and affected the testing accuracy and precision. In face of this problem, we developed a wireless acquiring system for the vibration table. The system is consisted of a three-channel analog-to-digital conversion, an acquisition control part, local data storage, network interface, wireless router and power management, etc. The analog-to-digital conversion part uses a 24-digit high-precision converter, which has a programmable amplifier at the front end of its artificial circuit, with the function of matching outputs with different amplifier from the vibration table. The acquisition control part uses a 32 bit ARM processor, with low-power dissipation, minute extension and high performance. The application software platform is written in Linux to make the system convenient for multitasking work. Large volume local digital storage is achieved by a 32G SD card, which is used for saving real time acquired data. Data transmission is achieved by network interface and wireless router, which can simplify the application software by the supported TCP/IP protocol. Besides, the acquisition system uses built-in power supply, which provides power to the system with Li-On rechargeable battery with high capacity, then all the cable link between the vibration table and the ground equipment have been removed. With all these changes, the whole system is immobilized on board of the vibration table after being packaged.

[D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3, small molecule synthetic peptide leptin mimetics, improve glycemic control in diet-induced obese (DIO) mice.

PubMed

Wang, Anke; Anderson, Brian M; Novakovic, Zachary M; Grasso, Patricia

2018-03-01

We have previously shown that following oral delivery in dodecyl maltoside (DDM), [D-Leu-4]-OB3 and its myristic acid conjugate, MA-[D-Leu-4]-OB3, improved energy balance and glucose homeostasis in genetically obese/diabetic mouse models. More recently, we have provided immunohistochemical evidence indicating that these synthetic peptide leptin mimetics cross the blood-brain barrier and concentrate in the area of the arcuate nucleus of the hypothalamus in normal C57BL/6J and Swiss Webster mice, in genetically obese ob/ob mice, and in diet-induced obese (DIO) mice. In the present study, we describe the effects of oral delivery of [D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3 on glycemic control in diet-induced (DIO) mice, a non-genetic rodent model of obesity and its associated insulin resistance, which more closely recapitulates common obesity and diabetes in humans. Male C57BL/6J and DIO mice, 17, 20, and 28 weeks of age, were maintained on a low-fat or high-fat diet and given vehicle (DDM) alone or [D-Leu-4]-OB3 or MA-[D-Leu-4]-OB3 in DDM by oral gavage for 12 or 14 days. Body weight gain, food and water intake, fasting blood glucose, oral glucose tolerance, and serum insulin levels were measured. Our data indicate that (1) [D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3 restore glucose tolerance in male DIO mice maintained on a high-fat diet to levels comparable to those of non-obese C57BL/6J wild-type mice of the same age and sex maintained on a low-fat diet; and (2) the influence of [D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3 on glycemic control appears to be independent of their effects on energy balance. These results suggest that [D-Leu-4]-OB3 and/or MA-[D-Leu-4]-OB3 may have application to the management of the majority of cases of common obesity in humans, a state characterized at least in part, by leptin resistance resulting from a defect in leptin transport across the blood-brain barrier. They further suggest that these small molecule synthetic peptide leptin mimetics, through their influence on glycemic control, may prevent the pre-diabetic state associated with most cases of common obesity from escalating into overt type 2 diabetes mellitus. Copyright © 2017 Elsevier Inc. All rights reserved.

Olfactory bulb and olfactory sulcus depths are associated with disease duration and attack frequency in multiple sclerosis patients.

PubMed

Tanik, Nermin; Serin, Halil Ibrahim; Celikbilek, Asuman; Inan, Levent Ertugrul; Gundogdu, Fatma

2015-11-15

Multiple sclerosis (MS) is a neuroinflammatory and neurodegenerative disease that progresses to axonal loss and demyelinization. Olfactory dysfunction in patients with MS has been reported frequently. We were interested in the associations of olfactory bulb (OB) and olfactory sulcus depth (OSD) with disease duration and attack frequency. We included 25 patients with MS and 30 age- and sex-matched controls in this study. The Expanded Disability Status Scale, Beck Depression Inventory, and Mini Mental State Examination were applied. OB, OSD, and magnetic resonance imaging plaque numbers were calculated. OB volume and OSD in patients with MS were significantly lower than those in the control group (right and left OB: p<0.001; right OSD: p=0.001; and left OSD: p=0.039). Disease duration was negatively correlated with right and left OB volume (right OB: r=-0.434, p=0.030 and left OB: r=-0.518, p=0.008). Attack frequency was negatively correlated with left OB volume and left OSD (left OB: r=-0.428, p=0.033 and left OSD: r=-0.431, p=0.032). The OB and OSD were atrophied significantly in patients with MS, and this was correlated with disease duration and attack frequency. The left side tended to be dominant. Copyright © 2015 Elsevier B.V. All rights reserved.

Oil Bodies Extracted from High-Fat and Low-Fat Soybeans: Stability and Composition During Storage.

PubMed

Wang, Qiu Ling; Li Cui, Chun; Jiang, Lian Zhou; Liu, Yue; Liang, Xin Ting; Hou, Jun Cai

2017-06-01

Soybeans contain oil bodies (OBs) that encapsulate triacylglycerols (TAGs) with a phospholipid monolayer carrying scattered proteins. In nature, soybean OBs can form natural emulsions in aqueous media and may serve as natural, minimally processed, stable, and pre-emulsified oil for addition into appropriate food systems. In this study, OBs were obtained by aqueous extraction from the mature seeds of 2 soybean crop cultivars, high-fat soybean and low-fat soybeans. The compositions of the extracted OBs were analyzed during storage at room temperature up to 14 d (pH = 7). The oxidative stability of these OBs, stored at 60 °C, was evaluated by measuring the presence of primary (lipid hydroperoxides) and secondary lipid oxidation products (malondialdehyde) by determining the standard peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS) value. During storage, the contents of unsaturated fatty acids, phospholipids, and tocopherols declined in both OBs, while their mean particle diameters (d 32 ) and ζ-potentials increased. The changes in PV and TBARS values exhibited a similar trend for both OBs, but the OBs from low-fat soybeans had significantly lower PV and higher TBARS values than the OBs from high-fat soybean cultivars (P < 0.05). Overall, the OBs from both soybean cultivars had good stability during storage. © 2017 Institute of Food Technologists®.

Surface Observation Climatic Summaries (SOCS) For Mather AFB, California

DTIC Science & Technology

1992-02-01

1100 SPEND (RTS) CE14 GEIS GE25 OBS GE14 GEl8 GE25 OBS GE14 GEl8 GE25 OBS GE14 GEl8 GE25 OBS CATEGORY A 1.7 .5 .1 930 1.6 .6 .1 930 1.6 .4 930 3.4 1.0...ITS) GE14 0E18 GE25 ORS GE14 GEIS GE25 OS GE14 GEl8 GE25 OBS GE14 GE18 GE25 OBS CATEGORY A 5.7 2.4 930 5.2 1.3 .2 930 1.7 .5 .2 930 1.5 .5 .1 930...TIME (LST) 0600 - 2000 ALL HOURS SPEED K75 GE14 GEl8 GE25 OBS GE14 GEl8 UE25 OS CAT Y A 3.5 1.1 .1 4650 2.8 .9

Genetic ablation of phosphatidylcholine transfer protein/StarD2 in ob/ob mice improves glucose tolerance without increasing energy expenditure.

PubMed

Krisko, Tibor I; LeClair, Katherine B; Cohen, David E

2017-03-01

Phosphatidylcholine transfer protein (PC-TP; synonym StarD2) is highly expressed in liver and oxidative tissues. PC-TP promotes hepatic glucose production during fasting and aggravates glucose intolerance in high fat fed mice. However, because PC-TP also suppresses thermogenesis in brown adipose tissue (BAT), its direct contribution to obesity-associated diabetes in mice remains unclear. Here we examined the effects of genetic PC-TP ablation on glucose homeostasis in leptin-deficient ob/ob mice, which exhibit both diabetes and altered thermoregulation. Mice lacking both PC-TP and leptin (Pctp -/- ;ob/ob) were prepared by crossing Pctp -/- with ob/+ mice. Glucose homeostasis was assessed by standard assays, and energy expenditure was determined by indirect calorimetry using a comprehensive laboratory animal monitoring system, which also recorded physical activity and food intake. Body composition was determined by NMR and hepatic lipids by enzymatic assays. Core body temperature was measured using a rectal thermocouple probe. Pctp -/- ;ob/ob mice demonstrated improved glucose homeostasis, as evidenced by markedly improved glucose and pyruvate tolerance tests, without changes in insulin tolerance. However, there were no differences in EE at any ambient temperature. There were also no effects of PC-TP expression on physical activity, food intake or core body temperature. Improved glucose tolerance in Pctp -/- ;ob/ob mice in the absence of increases in energy expenditure or core body temperature indicates a direct pathogenic role for PC-TP in diabetes in leptin deficient mice. Copyright © 2016 Elsevier Inc. All rights reserved.

Leptin differentially regulates STAT3 activation in the ob/ob mice adipose mesenchymal stem cells

USDA-ARS?s Scientific Manuscript database

Leptin-deficient genetically obese ob/ob mice exhibit adipocyte hypertrophy and hyperplasia as well as elevated adipose tissue and systemic inflammation. Studies have shown that multipotent stem cells isolated from adult adipose tissue can differentiate into adipocytes ex vivo and thereby contribute...

Mapping the extent of thinned continental crust across the Orphan Basin, offshore Newfoundland, Canada, using a combination of vintage and new seismic refraction/wide-angle reflection data

NASA Astrophysics Data System (ADS)

Welford, J. Kim; Dehler, Sonya; Funck, Thomas

2017-04-01

The SIGNAL (Seismic Investigations off Greenland, Newfoundland and Labrador) 2009 cruise was undertaken by the Geological Survey of Canada (GSC) and the Geological Survey of Denmark and Greenland (GEUS), with scientific contributions from Dalhousie University, to collect refraction/wide-angle reflection (RWAR) profiles as part of each country's continental shelf program under UNCLOS (United Nations Convention on the Law of the Sea) Article 76. Line 1 extended from the Bonavista Platform off Newfoundland, across the Orphan Basin, to Orphan Knoll and beyond into oceanic crust. The line followed the same track as an earlier seismic refraction line and ocean-bottom seismometer (OBS) locations were chosen to complement and to extend the original station coverage. The final crustal velocity model across Orphan Basin shows thinned continental crust (15 to 20 km thick) beneath most of the basin with thinner crust (10 km thick) immediately outboard of the Bonavista Platform, interpreted as a failed rift zone. Seaward of the failed rift, the velocity structure of the thinned continental crust is generally uniform over 250 km toward Orphan Knoll. Immediately outboard of Orphan Knoll, the crust thins to 8 km and exhibits a velocity structure consistent with oceanic crust. The results from modelling of the combined refraction/wide-angle reflection dataset support an extension of Canada's continental shelf beyond the seaward limits of the Orphan Basin.

Hunting for shallow slow-slip events at Cascadia

NASA Astrophysics Data System (ADS)

Tan, Y. J.; Bletery, Q.; Fan, W.; Janiszewski, H. A.; Lynch, E.; McCormack, K. A.; Phillips, N. J.; Rousset, B.; Seyler, C.; French, M. E.; Gaherty, J. B.; Regalla, C.

2017-12-01

The discovery of slow earthquakes at subduction zones is one of the major breakthroughs of Earth science in the last two decades. Slow earthquakes involve a wide spectrum of fault slip behaviors and seismic radiation patterns, such as tremor, low-frequency earthquakes, and slow-slip events. The last of these are particularly interesting due to their large moment releases accompanied by minimal ground shaking. Slow-slip events have been reported at various subduction zones ; most of these slow-slip events are located down-dip of the megathrust seismogenic zone, while a few up-dip cases have recently been observed at Nankai and New Zealand. Up-dip slow-slip events illuminate the structure of faulting environments and rupture mechanisms of tsunami earthquakes. Their possible presence and location at a particular subduction zone can help assess earthquake and tsunami hazard for that region. However, their typical location distant from the coast requires the development of techniques using offshore instrumentation. Here, we investigate the absolute pressure gauges (APG) of the Cascadia Initiative, a four year amphibious seismic experiment, to search for possible shallow up-dip slow-slip events in the Cascadia subduction zone. These instruments are collocated with ocean bottom seismometers (OBS) and located close to buoys and onshore GPS stations, offering the opportunity to investigate the utility of multiple datasets. Ultimately, we aim to develop a protocol to analyze APG data for offshore shallow slow-slip event detections and quantify uncertainties, with direct applications to understanding the up-dip subduction interface system in Cascadia.

Evaluation of Two Guralp Preamplifiers for GS21 Seismometer Application.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion J.; Slad, George William

2015-08-01

Sandia National Laboratories has tested and evaluated two Guralp preamplifiers for use with a GS21 seismometer application. The two preamplifiers have a gain factor of 61.39. The purpose of the preamplifier evaluation was to determine a measured gain factor, transfer function, total harmonic distortion, self-noise, application passband, dynamic range, seismometer calibration pass-through, and to comment on any issues encountered during the evaluation. The test results included in this report were in response to static, tonal, and dynamic input signals. The Guralp GS21 preamplifiers are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treatymore » Organization (CTBTO). Test methodologies used were based on IEEE Standards 1057 for Digitizing Waveform Recorders and 1241 for Analog to Digital Converters« less

Automated identification of OB associations in M31

NASA Technical Reports Server (NTRS)

Magnier, Eugene A.; Battinelli, Paolo; Lewin, Walter H. G.; Haiman, Zoltan; Paradijs, Jan Van; Hasinger, Guenther; Pietsch, Wolfgang; Supper, Rodrigo; Truemper, Joachim

1993-01-01

A new identification of OB associations in M31 has been performed using the Path Linkage Criterion (PLC) technique of Battinelli (1991). We found 174 associations with a very small contamination (less than 5%) by random clumps of stars. The expected total number and average size of OB associations in the region of M 31 covered by our data set (Magnier et al. 1992) are approximately 280 and approximately 90 pc, respectively. M31 associations therefore have sizes similar to those of OB associations observed in nearby galaxies, so that we can consider them to be classical OB associations. This list of OB associations will be used for the study of the spatial distribution of OB associations and their correlation with other objects. Taking into account the fact that we do not cover the entire disk of M31, we extrapolate a total number of association in M31 of approximately 420.

Organic brain syndrome and aging. A six-year follow-up of surviving twins.

PubMed

Jarvik, L F; Ruth, V; Matsuyama, S S

1980-03-01

The development of organic brain syndrome (OBS) was studied in a small group of survivors from a longitudinal investigation of aging twins. At the time of initial evaluation, the frequency of moderate to severe OBS was 25%. Among the 22 survivors who had a second psychiatric evaluation after approximately six years, the corrected rate for the development of OBS among those without it at the initial examination was 16%. Thus, the vast majority of those diagnosed as being without OBS at about the age of 80 years remained asymptomatic in subsequent years, supporting the view that OBS is not a necessary concomitant of old age, but the result of disease for which prevention and cure should be sought. Persons originally diagnosed as having OBS had the higher mortality, an observation in accord with prior reports in the literature. In the present study, the increased mortality was related to the severity of OBS but apparently independent of coexisting physical illness, again supporting the argument that OBS represents pathological as distinct from physiological aging.

Structural anatomy of telomere OB proteins.

PubMed

Horvath, Martin P

2011-10-01

Telomere DNA-binding proteins protect the ends of chromosomes in eukaryotes. A subset of these proteins are constructed with one or more OB folds and bind with G+T-rich single-stranded DNA found at the extreme termini. The resulting DNA-OB protein complex interacts with other telomere components to coordinate critical telomere functions of DNA protection and DNA synthesis. While the first crystal and NMR structures readily explained protection of telomere ends, the picture of how single-stranded DNA becomes available to serve as primer and template for synthesis of new telomere DNA is only recently coming into focus. New structures of telomere OB fold proteins alongside insights from genetic and biochemical experiments have made significant contributions towards understanding how protein-binding OB proteins collaborate with DNA-binding OB proteins to recruit telomerase and DNA polymerase for telomere homeostasis. This review surveys telomere OB protein structures alongside highly comparable structures derived from replication protein A (RPA) components, with the goal of providing a molecular context for understanding telomere OB protein evolution and mechanism of action in protection and synthesis of telomere DNA.

Structural anatomy of telomere OB proteins

PubMed Central

Horvath, Martin P.

2015-01-01

Telomere DNA-binding proteins protect the ends of chromosomes in eukaryotes. A subset of these proteins are constructed with one or more OB folds and bind with G+T-rich single-stranded DNA found at the extreme termini. The resulting DNA-OB protein complex interacts with other telomere components to coordinate critical telomere functions of DNA protection and DNA synthesis. While the first crystal and NMR structures readily explained protection of telomere ends, the picture of how single-stranded DNA becomes available to serve as primer and template for synthesis of new telomere DNA is only recently coming into focus. New structures of telomere OB fold proteins alongside insights from genetic and biochemical experiments have made significant contributions towards understanding how protein-binding OB proteins collaborate with DNA-binding OB proteins to recruit telomerase and DNA polymerase for telomere homeostasis. This review surveys telomere OB protein structures alongside highly comparable structures derived from replication protein A (RPA) components, with the goal of providing a molecular context for understanding telomere OB protein evolution and mechanism of action in protection and synthesis of telomere DNA. PMID:21950380

Oral Administration of Apple Procyanidins Ameliorates Insulin Resistance via Suppression of Pro-Inflammatory Cytokine Expression in Liver of Diabetic ob/ob Mice.

PubMed

Ogura, Kasane; Ogura, Masahito; Shoji, Toshihiko; Sato, Yuichi; Tahara, Yumiko; Yamano, Gen; Sato, Hiroki; Sugizaki, Kazu; Fujita, Naotaka; Tatsuoka, Hisato; Usui, Ryota; Mukai, Eri; Fujimoto, Shimpei; Inagaki, Nobuya; Nagashima, Kazuaki

2016-11-23

Procyanidins, the main ingredient of apple polyphenols, are known to possess antioxidative and anti-inflammatory effects associated closely with the pathophysiology of insulin resistance and type 2 diabetes. We investigated the effects of orally administered apple procyanidins (APCs) on glucose metabolism using diabetic ob/ob mice. We found no difference in body weight or body composition between mice treated with APCs and untreated mice. A 4 week oral administration of APCs containing water [0.5% (w/v)] ameliorated glucose tolerance, insulin resistance, and hepatic gluconeogenesis in ob/ob mice. APCs also suppressed the increase in the level of the pancreatic β-cell. Insulin-stimulated Akt phosphorylation was significantly enhanced; pro-inflammatory cytokine expression levels were significantly decreased, and c-Jun N-terminal kinase phosphorylation was downregulated in the liver of those mice treated with APCs. In conclusion, APCs ameliorate insulin resistance by improving hepatic insulin signaling through suppression of hepatic inflammation in ob/ob mice, which may be a mechanism with possible beneficial health effects of APCs in disturbed glucose metabolism.

Oligoclonal bands and periventricular lesions in multiple sclerosis will not increase blood-brain barrier permeability.

PubMed

Akaishi, Tetsuya; Takahashi, Toshiyuki; Nakashima, Ichiro

2018-04-15

To elucidate the etiology and clinical significance of periventricular lesions (PVLs) and oligoclonal bands (OB) in multiple sclerosis (MS). We enrolled a total of 97 MS patients (67 OB-positive and 30 OB-negative) who were negative both for anti-aquaporin-4 (AQP4) autoantibody and anti-myelin oligodendrocyte glycoprotein (MOG) antibody. In these patients, comprehensive data including clinical, laboratory, and MRI were collected to investigate the significance of OB and PVLs. Within the MS patients, OB-positivity and the number of PVLs were associated each other. Both of OB-positivity and PVLs did not affect clinical severity or relapse rate, though the patients with ≥3 PVLs showed faster cerebral atrophy than those with <3 PVLs. The patients with OB or ≥3 PVLs showed lower values of quotient of albumin (QAlb), a biomarker of blood-brain barrier (BBB)-permeability and possibly reflects the ongoing disease activity, and lower protein levels in cerebrospinal fluid (CSF). The causal relationship between the decreased QAlb and OB or ≥3 PVLs was not determined. OB and PVLs were associated each other, but they did not affect the clinical course or increased the BBB-permeability within MS patients. Copyright © 2018 Elsevier B.V. All rights reserved.

Scale Factor and Noise Performance Tests of the Bendix Corporation Rate Gyro Assembly (RGA).

DTIC Science & Technology

1980-08-01

tiltmeters , seismometers, and an ambient temperature monitor. 3.2 Test Support Equipment Bendix supplied all necessary test support equipment and...001A 2-Axis Tiltmeter Electrotechnical Lab EV22C Portable Seismic Mon- itor (PRM) Sensors USAF Sieler Laboratory PSM Electronics Rockland 816...acquisition system recorded the tiltmeter , seismometer, and temperature data on magnetic tape. The seismic, tilt, and temperature information was filtered

Compilation of Reprints Number 63.

DTIC Science & Technology

1986-03-01

Michel Be6, Stephen H1. Johnson, and E.F. Chiburis PRELIMINARY SEISMIC REFRACTION RESULTS USING A BOREHOLE SEISMOMETER IN DEEP SEA DRILLING PROJECT HOLE...refraction data with wells drilled on land and offshore reflection profiles permits tentative identification of geologic sequences on the basis of...PERIOD CO’VEAEO PRELIMINARY SEISMIC REFRACTION RESULTS USING A Rern BOREHOLE SEISMOMETER IN DEEP SEA DRILLING ~ rn PROJECT HOLE 395A 6.PERFORMING ORG

Oil Bodies and Oleosins in Physcomitrella Possess Characteristics Representative of Early Trends in Evolution1[W][OA

PubMed Central

Huang, Chien-Yu; Chung, Chun-I; Lin, Yao-Cheng; Hsing, Yue-Ie Caroline; Huang, Anthony H.C.

2009-01-01

Searches of sequenced genomes of diverse organisms revealed that the moss Physcomitrella patens is the most primitive organism possessing oleosin genes. Microscopy examination of Physcomitrella revealed that oil bodies (OBs) were abundant in the photosynthetic vegetative gametophyte and the reproductive spore. Chromatography illustrated the neutral lipids in OBs isolated from the gametophyte to be largely steryl esters and triacylglycerols, and SDS-PAGE showed the major proteins to be oleosins. Reverse transcription-PCR revealed the expression of all three oleosin genes to be tissue specific. This tissue specificity was greatly altered via alternative splicing, a control mechanism of oleosin gene expression unknown in higher plants. During the production of sex organs at the tips of gametophyte branches, the number of OBs in the top gametophyte tissue decreased concomitant with increases in the number of peroxisomes and level of transcripts encoding the glyoxylate cycle enzymes; thus, the OBs are food reserves for gluconeogenesis. In spores during germination, peroxisomes adjacent to OBs, along with transcripts encoding the glyoxylate cycle enzymes, appeared; thus, the spore OBs are food reserves for gluconeogenesis and equivalent to seed OBs. The one-cell-layer gametophyte could be observed easily with confocal microscopy for the subcellular OBs and other structures. Transient expression of various gene constructs transformed into gametophyte cells revealed that all OBs were linked to the endoplasmic reticulum (ER), that oleosins were synthesized in extended regions of the ER, and that two different oleosins were colocated in all OBs. PMID:19420327

Macronutrients and micronutrients of soybean oil bodies extracted at different pH.

PubMed

Chen, Yeming; Cao, Yanyun; Zhao, Luping; Kong, Xiangzhen; Hua, Yufei

2014-07-01

In this study, the macronutrients and micronutrients of pH 6.8, 8.0, 9.5, and 11.0 extracted soybean oil bodies (OBs) were examined, revealing that soybean OBs might be used as a natural carrier for bioactive components (unsaturated fatty acids, phospholipid, tocopherol, and phytosterol). pH 6.8 extracted OBs (dry basis) contained 85.88% neutral lipid, 8.18% protein, and 5.85% polar lipid (mainly phospholipid) by gravimetric analysis. The percentage of neutral lipid was increased, while those of protein and polar lipid were decreased with increasing pH. Tocopherol (about 75 mg/100 g neutral lipid of OBs) was not affected, while phytosterol was decreased (136 to 110 mg/100 g neutral lipid of OBs) with increasing pH. The detectable total monosaccaride (galactosamine, glucosamine, and glucose) content of extracted OBs was low and also decreased (35.80 to 6.13 mg/100 g neutral lipid of OBs) with increasing pH. The protein of extracted OBs had higher percentage of essential amino acids than soybean protein isolate with tryptophan and methionine as limited amino acids. The fatty acid composition of extracted OBs was rich in linoleic acid (about 59%), oleic acid (about 20%), and α-linolenic acid (about 7%). Oil bodies (OBs) from soybean and other plant seeds are greatly examined owing to their potential utilizations in food ingredients. The determination of its macronutrients and micronutrients would be very meaningful for its efficient utilization in the future. © 2014 Institute of Food Technologists®

Viking-2 Seismometer Measurements on Mars: PDS Data Archive and Meteorological Applications

NASA Astrophysics Data System (ADS)

Lorenz, Ralph D.; Nakamura, Yosio; Murphy, James R.

2017-11-01

A data product has been generated and archived on the NASA Planetary Data System (Geosciences Node), which presents the seismometer readings of Viking Lander 2 in an easy-to-access form, for both the raw ("high rate") waveform records and the compressed ("event mode") amplitude and frequency records. In addition to the records themselves, a separate summary file for each instrument mode lists key statistics of each record together with the meteorological measurements made closest in time to the seismic record. This juxtaposition facilitates correlation of the seismometer instrument response to different meteorological conditions, or the selection of seismic data during which wind disturbances can be expected to be small. We summarize data quality issues and also discuss lander-generated seismic signals, due to operation of the sampling arm or other systems, which may be of interest for prospective missions to other bodies. We review wind-seismic correlation, the "Martian solar day (sol) 80" candidate seismic event, and identify the seismic signature of a probable dust devil vortex on sol 482 : the seismometer data allow an estimate of the peak wind, occurring between coarsely spaced meteorology measurements. We present code to generate the plots in this paper to illustrate use of the data product.

Sirtuin-2 Regulates Sepsis Inflammation in ob/ob Mice

PubMed Central

Wang, Xianfeng; Buechler, Nancy L.; Martin, Ayana; Wells, Jonathan; Yoza, Barbara; McCall, Charles E.; Vachharajani, Vidula

2016-01-01

Objective Obesity increases morbidity and resource utilization in sepsis patients. Sepsis transitions from early/hyper-inflammatory to late/hypo-inflammatory phase. Majority of sepsis-mortality occurs during the late sepsis; no therapies exist to treat late sepsis. In lean mice, we have shown that sirtuins (SIRTs) modulate this transition. Here, we investigated the role of sirtuins, especially the adipose-tissue abundant SIRT-2 on transition from early to late sepsis in obese with sepsis. Methods Sepsis was induced using cecal ligation and puncture (CLP) in ob/ob mice. We measured microvascular inflammation in response to lipopolysaccharide/normal saline re-stimulation as a “second-hit” (marker of immune function) at different time points to track phases of sepsis in ob/ob mice. We determined SIRT-2 expression during different phases of sepsis. We studied the effect of SIRT-2 inhibition during the hypo-inflammatory phase on immune function and 7-day survival. We used a RAW264.7 (RAW) cell model of sepsis for mechanistic studies. We confirmed key findings in diet induced obese (DIO) mice with sepsis. Results We observed that the ob/ob-septic mice showed an enhanced early inflammation and a persistent and prolonged hypo-inflammatory phase when compared to WT mice. Unlike WT mice that showed increased SIRT1 expression, we found that SIRT2 levels were increased in ob/ob mice during hypo-inflammation. SIRT-2 inhibition in ob/ob mice during the hypo-inflammatory phase of sepsis reversed the repressed microvascular inflammation in vivo via activation of endothelial cells and circulating leukocytes and significantly improved survival. We confirmed the key finding of the role of SIRT2 during hypo-inflammatory phase of sepsis in this project in DIO-sepsis mice. Mechanistically, in the sepsis cell model, SIRT-2 expression modulated inflammatory response by deacetylation of NFκBp65. Conclusion SIRT-2 regulates microvascular inflammation in obese mice with sepsis and may provide a novel treatment target for obesity with sepsis. PMID:27500833

Impact of diet on the cardiovascular risk profile of Japanese immigrants living in Brazil: contributions of World Health Organization CARDIAC and MONALISA studies.

PubMed

Moriguchi, E H; Moriguchi, Y; Yamori, Y

2004-12-01

1. Japanese immigrants from Okinawa living in Brazil have a higher mortality from cardiovascular diseases and have their mean life expectancy shortened compared with their counterparts living in Japan. 2. A cross-sectional study comparing Okinawans living in Okinawa (OO) and Okinawan immigrants living in Brazil (OB) was designed to characterize the dietary factors that could interfere with the profile of cardiovascular risk factors and with this reduction on the life expectancy when Okinawans emigrate to Brazil. 3. In total, 234 OO and 160 OB (aged 45-59 years) were recruited to the present study to undergo medical and dietary history, blood pressure measurement, electrocardiograph (ECG), blood tests and 24 h food/urine collection. 4. In the present study, OO subjects presented with 37% less obesity and 50% less systemic hypertension than OB. The OB subjects used threefold more antihypertensive medication than OO. Meat intake was 34% higher in OB than OO, whereas fish intake was sevenfold higher in OO than OB. Serum potassium levels were 10% higher in OO than OB. Urinary taurine (an index of seafood intake) was 43% higher in OO than OB. Urinary isoflavones (an index of the intake of soy products) were significantly lower in OB than in OO. Of acid (20:5) and docosahexaenoic acid (22:6) were two- and threefold higher in OO than OB, respectively. 5. The rate of ischaemic ECG changes in OO subjects was only 50% of that of OB subjects. 6. There were no differences in the smoking rate between OO and OB subjects. 7. The results of the present study suggest that coronary risk factors and cardiovascular health are not only regulated by genetic factors, but that the impact of lifestyle (mainly diet) can be large enough to modulate the expression of genes.

Importance of reward and prefrontal circuitry in hunger and satiety: Prader-Willi syndrome vs simple obesity.

PubMed

Holsen, L M; Savage, C R; Martin, L E; Bruce, A S; Lepping, R J; Ko, E; Brooks, W M; Butler, M G; Zarcone, J R; Goldstein, J M

2012-05-01

The majority of research on obesity (OB) has focused primarily on clinical features (eating behavior, adiposity measures) or peripheral appetite-regulatory peptides (leptin, ghrelin). However, recent functional neuroimaging studies have demonstrated that some reward circuitry regions that are associated with appetite-regulatory hormones are also involved in the development and maintenance of OB. Prader-Willi syndrome (PWS), characterized by hyperphagia and hyperghrelinemia reflecting multi-system dysfunction in inhibitory and satiety mechanisms, serves as an extreme model of genetic OB. Simple (non-PWS) OB represents an OB-control state. This study investigated subcortical food motivation circuitry and prefrontal inhibitory circuitry functioning in response to food stimuli before and after eating in individuals with PWS compared with OB. We hypothesized that groups would differ in limbic regions (that is, hypothalamus, amygdala) and prefrontal regions associated with cognitive control (that is, dorsolateral prefrontal cortex (DLPFC), orbitofrontal cortex (OFC) after eating. A total of 14 individuals with PWS, 14 BMI- and age-matched individuals with OB, and 15 age-matched healthy-weight controls viewed food and non-food images while undergoing functional MRI before (pre-meal) and after (post-meal) eating. Using SPM8, group contrasts were tested for hypothesized regions: hypothalamus, nucleus accumbens (NAc), amygdala, hippocampus, OFC, medial PFC and DLPFC. Compared with OB and HWC, PWS demonstrated higher activity in reward/limbic regions (NAc, amygdala) and lower activity in the hypothalamus and hippocampus in response to food (vs non-food) images pre-meal. Post meal, PWS exhibited higher subcortical activation (hypothalamus, amygdala, hippocampus) compared with OB and HWC. OB showed significantly higher activity versus PWS and HWC in cortical regions (DLPFC, OFC) associated with inhibitory control. In PWS, compared with OB per se, results suggest hyperactivations in subcortical reward circuitry and hypoactivations in cortical inhibitory regions after eating, which provides evidence of neural substrates associated with variable abnormal food motivation phenotypes in PWS and simple OB.

Soluble Leptin Receptor Predicts Insulin Sensitivity and Correlates With Upregulation of Metabolic Pathways in Men.

PubMed

Sommer, Christine; Lee, Sindre; Gulseth, Hanne Løvdal; Jensen, Jørgen; Drevon, Christian A; Birkeland, Kåre Inge

2018-03-01

Plasma soluble leptin receptor (sOb-R) seems protective of gestational and type 2 diabetes in observational studies, but the mechanisms are unknown. sOb-R is formed by ectodomain shedding of membrane-bound leptin receptors (Ob-Rs), but its associations with messenger RNA (mRNA) expression are scarcely explored. To explore associations between plasma levels of sOb-R and (1) insulin sensitivity, (2) mRNA pathways in adipose tissue and skeletal muscle, and (3) mRNA of candidate genes for sOb-R generation in adipose tissue and skeletal muscle. The MyoGlu study included 26 sedentary, middle-aged men who underwent a 12-week intensive exercise intervention. We measured plasma sOb-R with enzyme-linked immunosorbent assay, insulin sensitivity with a hyperinsulinemic euglycemic clamp, and mRNA in skeletal muscle and adipose tissue with high-throughput sequencing. Baseline plasma sOb-R was strongly associated with baseline glucose infusion rate (GIR) [β (95% confidence interval), 1.19 (0.57 to 1.82) mg/kg/min, P = 0.0006] and GIR improvement after the exercise intervention [0.58 (0.03 to 1.12) mg/kg/min, P = 0.039], also independently of covariates, including plasma leptin. In pathway analyses, high plasma sOb-R correlated with upregulation of metabolic pathways and downregulation of inflammatory pathways in both adipose tissue and skeletal muscle. In skeletal muscle, mRNA of LEPROT and LEPROTL1 (involved in Ob-R cell surface expression) and ADAM10 and ADAM17 (involved sOb-R-shedding) increased after the exercise intervention. Higher plasma sOb-R was associated with improved GIR, upregulation of metabolic pathways, and downregulation of inflammatory pathways, which may be possible mechanisms for the seemingly protective effect of plasma sOb-R on subsequent risk of gestational and type 2 diabetes found in observational studies.

Gender Dimorphism in Skeletal Muscle Leptin Receptors, Serum Leptin and Insulin Sensitivity

PubMed Central

Guerra, Borja; Fuentes, Teresa; Delgado-Guerra, Safira; Guadalupe-Grau, Amelia; Olmedillas, Hugo; Santana, Alfredo; Ponce-Gonzalez, Jesus Gustavo; Dorado, Cecilia; Calbet, José A. L.

2008-01-01

To determine if there is a gender dimorphism in the expression of leptin receptors (OB-R170, OB-R128 and OB-R98) and the protein suppressor of cytokine signaling 3 (SOCS3) in human skeletal muscle, the protein expression of OB-R, perilipin A, SOCS3 and alpha-tubulin was assessed by Western blot in muscle biopsies obtained from the m. vastus lateralis in thirty-four men (age = 27.1±6.8 yr) and thirty-three women (age = 26.7±6.7 yr). Basal serum insulin concentration and HOMA were similar in both genders. Serum leptin concentration was 3.4 times higher in women compared to men (P<0.05) and this difference remained significant after accounting for the differences in percentage of body fat or soluble leptin receptor. OB-R protein was 41% (OB-R170, P<0.05) and 163% (OB-R128, P<0.05) greater in women than men. There was no relationship between OB-R expression and the serum concentrations of leptin or 17β-estradiol. In men, muscle OB-R128 protein was inversely related to serum free testosterone. In women, OB-R98 and OB-R128 were inversely related to total serum testosterone concentration, and OB-R128 to serum free testosterone concentration. SOCS3 protein expression was similar in men and women and was not related to OB-R. In women, there was an inverse relationship between the logarithm of free testosterone and SCOS3 protein content in skeletal muscle (r = −0.46, P<0.05). In summary, there is a gender dimorphism in skeletal muscle leptin receptors expression, which can be partly explained by the influence of testosterone. SOCS3 expression in skeletal muscle is not up-regulated in women, despite very high serum leptin concentrations compared to men. The circulating form of the leptin receptor can not be used as a surrogate measure of the amount of leptin receptors expressed in skeletal muscles. PMID:18941624

The fiber optic gyroscope - a portable rotational ground motion sensor

NASA Astrophysics Data System (ADS)

Wassermann, J. M.; Bernauer, F.; Guattari, F.; Igel, H.

2016-12-01

It was already shown that a portable broadband rotational ground motion sensor will have large impact on several fields of seismological research such as volcanology, marine geophysics, seismic tomography and planetary seismology. Here, we present results of tests and experiments with one of the first broadband rotational motion sensors available. BlueSeis-3A, is a fiber optic gyroscope (FOG) especially designed for the needs of seismology, developed by iXBlue, France, in close collaboration with researchers financed by the European Research council project ROMY (Rotational motions - a new observable for seismology). We first present the instrument characteristics which were estimated by different standard laboratory tests, e.g. self noise using operational range diagrams or Allan deviation. Next we present the results of a field experiment which was designed to demonstrate the value of a 6C measurement (3 components of translation and 3 components of rotation). This field test took place at Mt. Stromboli volcano, Italy, and is accompanied by seismic array installation to proof the FOG output against more commonly known array derived rotation. As already shown with synthetic data an additional direct measurement of three components of rotation can reduce the ambiguity in source mechanism estimation and can be taken to correct for dynamic tilt of the translational sensors (i.e. seismometers). We can therefore demonstrate that the deployment of a weak motion broadband rotational motion sensor is in fact producing superior results by a reduction of the number of deployed instruments.

An Analysis of the Impact of Outward Bound on Twelve High Schools.

ERIC Educational Resources Information Center

Schulze, Joseph R.

Describing and analyzing the impact of Outward Bound (OB) programs on 12 high schools which reflect OB involvement varying from 1 to 5 years and include urban, suburban, and rural (public, private, boarding, and day) schools, this 1970-71 report is aimed at furthering OB philosophy and method. The report presents OB program: background; evaluation…

Complete Genome Sequence of Escherichia coli Strain M8, Isolated from ob/ob Mice

PubMed Central

Siddharth, Jay; Membrez, Mathieu; Chakrabarti, Anirikh; Betrisey, Bertrand; Chou, Chieh Jason

2017-01-01

ABSTRACT Escherichia coli is one of the common inhabitants of the mammalian gastrointestinal track. We isolated a strain from an ob/ob mouse and performed whole-genome sequencing, which yielded a chromosome of ~5.1 Mb and three plasmids of ~160 kb, ~6 kb, and ~4 kb. PMID:28572322

Geodetic Infrastructure, Data, Education and Community Engagement in Response to Earthquakes and Other Geophysical Events: An Overview of UNAVCO Support Resources Plus Highlights from Recent Event Response

NASA Astrophysics Data System (ADS)

Phillips, D. A.; Meertens, C. M.; Mattioli, G. S.; Miller, M. M.; Charlevoix, D. J.; Maggert, D.; Hodgkinson, K. M.; Henderson, D. B.; Puskas, C. M.; Bartel, B. A.; Baker, S.; Blume, F.; Normandeau, J.; Feaux, K.; Galetzka, J.; Williamson, H.; Pettit, J.; Crosby, C. J.; Boler, F. M.

2015-12-01

UNAVCO responds to community requests for support during and following significant geophysical events such as earthquakes, volcanic activity, landslides, glacial and ice-sheet movements, unusual uplift or subsidence, extreme meteorological events, or other hazards. UNAVCO can also respond proactively to events in anticipation of community demand for relevant data, data products or other services. Recent major events to which UNAVCO responded include the 2015 M7.8 Nepal EQ, the 2014 M6.0 American Canyon (Napa) EQ, the 2014 M8.2 Chile EQ, the 2011 M9.0 Tohoku, Japan EQ and tsunami, the 2010 M8.8 Maule, Chile EQ, and the 2010 M7.0 Haiti EQ. UNAVCO provided geophysical event response support for 15 events in 2014 alone. UNAVCO event response resources include geodetic infrastructure, data, and education and community engagement. Specific support resources include: field engineering personnel; continuous and campaign GNSS/GPS station deployment; real-time and/or high rate field GNSS/GPS station upgrades or deployment; data communications and power systems deployment; tiltmeter, strainmeter, and borehole seismometer deployments; terrestrial laser scanning (TLS a.k.a. ground-based LiDAR); InSAR data support; education and community engagement assistance or products; data processing services; generation of custom GNSS/GPS or borehole data sets and products; equipment shipping and logistics coordination; and assistance with RAPID proposal preparation, budgeting, and submission. The most critical aspect of a successful event response is effective and efficient communication. To facilitate such communication, UNAVCO creates event response web pages describing the event and the support being provided, and in the case of major events also provides an online event response forum. These resources are shared broadly with the geophysical community through multiple dissemination strategies including social media of UNAVCO and partner organizations. We will provide an overview of resources available to the community from UNAVCO in response to events. We will also highlight examples of the infrastructure, data and data products, and education and community engagement support provided by UNAVCO for major recent events.

The effect of spaceflight on mouse olfactory bulb volume, neurogenesis, and cell death indicates the protective effect of novel environment.

PubMed

Latchney, Sarah E; Rivera, Phillip D; Mao, Xiao W; Ferguson, Virginia L; Bateman, Ted A; Stodieck, Louis S; Nelson, Gregory A; Eisch, Amelia J

2014-06-15

Space missions necessitate physiological and psychological adaptations to environmental factors not present on Earth, some of which present significant risks for the central nervous system (CNS) of crewmembers. One CNS region of interest is the adult olfactory bulb (OB), as OB structure and function are sensitive to environmental- and experience-induced regulation. It is currently unknown how the OB is altered by spaceflight. In this study, we evaluated OB volume and neurogenesis in mice shortly after a 13-day flight on Space Shuttle Atlantis [Space Transport System (STS)-135] relative to two groups of control mice maintained on Earth. Mice housed on Earth in animal enclosure modules that mimicked the conditions onboard STS-135 (AEM-Ground mice) had greater OB volume relative to mice maintained in standard housing on Earth (Vivarium mice), particularly in the granule (GCL) and glomerular (GL) cell layers. AEM-Ground mice also had more OB neuroblasts and fewer apoptotic cells relative to Vivarium mice. However, the AEM-induced increase in OB volume and neurogenesis was not seen in STS-135 mice (AEM-Flight mice), suggesting that spaceflight may have negated the positive effects of the AEM. In fact, when OB volume of AEM-Flight mice was considered, there was a greater density of apoptotic cells relative to AEM-Ground mice. Our findings suggest that factors present during spaceflight have opposing effects on OB size and neurogenesis, and provide insight into potential strategies to preserve OB structure and function during future space missions. Copyright © 2014 the American Physiological Society.

G Protein–Coupled Receptor Kinase 2, With β-Arrestin 2, Impairs Insulin-Induced Akt/Endothelial Nitric Oxide Synthase Signaling in ob/ob Mouse Aorta

PubMed Central

Taguchi, Kumiko; Matsumoto, Takayuki; Kamata, Katsuo; Kobayashi, Tsuneo

2012-01-01

In type 2 diabetes, impaired insulin-induced Akt/endothelial nitric oxide synthase (eNOS) signaling may decrease the vascular relaxation response. Previously, we reported that this response was negatively regulated by G protein–coupled receptor kinase 2 (GRK2). In this study, we investigated whether/how in aortas from ob/ob mice (a model of type 2 diabetes) GRK2 and β-arrestin 2 might regulate insulin-induced signaling. Endothelium-dependent relaxation was measured in aortic strips. GRK2, β-arrestin 2, and Akt/eNOS signaling pathway proteins and activities were mainly assayed by Western blotting. In ob/ob (vs. control [Lean]) aortas: 1) insulin-induced relaxation was reduced, and this deficit was prevented by GRK2 inhibitor, anti-GRK2 antibody, and an siRNA specifically targeting GRK2. The Lean aorta relaxation response was reduced to the ob/ob level by pretreatment with an siRNA targeting β-arrestin 2. 2) Insulin-stimulated Akt and eNOS phosphorylations were decreased. 3) GRK2 expression in membranes was elevated, and, upon insulin stimulation, this expression was further increased, but β-arrestin 2 was decreased. In ob/ob aortic membranes under insulin stimulation, the phosphorylations of Akt and eNOS were augmented by GRK2 inhibitor. In mouse aorta, GRK2 may be, upon translocation, a key negative regulator of insulin responsiveness and an important regulator of the β-arrestin 2/Akt/eNOS signaling, which is implicated in diabetic endothelial dysfunction. PMID:22688330

G protein-coupled receptor kinase 2, with β-arrestin 2, impairs insulin-induced Akt/endothelial nitric oxide synthase signaling in ob/ob mouse aorta.

PubMed

Taguchi, Kumiko; Matsumoto, Takayuki; Kamata, Katsuo; Kobayashi, Tsuneo

2012-08-01

In type 2 diabetes, impaired insulin-induced Akt/endothelial nitric oxide synthase (eNOS) signaling may decrease the vascular relaxation response. Previously, we reported that this response was negatively regulated by G protein-coupled receptor kinase 2 (GRK2). In this study, we investigated whether/how in aortas from ob/ob mice (a model of type 2 diabetes) GRK2 and β-arrestin 2 might regulate insulin-induced signaling. Endothelium-dependent relaxation was measured in aortic strips. GRK2, β-arrestin 2, and Akt/eNOS signaling pathway proteins and activities were mainly assayed by Western blotting. In ob/ob (vs. control [Lean]) aortas: 1) insulin-induced relaxation was reduced, and this deficit was prevented by GRK2 inhibitor, anti-GRK2 antibody, and an siRNA specifically targeting GRK2. The Lean aorta relaxation response was reduced to the ob/ob level by pretreatment with an siRNA targeting β-arrestin 2. 2) Insulin-stimulated Akt and eNOS phosphorylations were decreased. 3) GRK2 expression in membranes was elevated, and, upon insulin stimulation, this expression was further increased, but β-arrestin 2 was decreased. In ob/ob aortic membranes under insulin stimulation, the phosphorylations of Akt and eNOS were augmented by GRK2 inhibitor. In mouse aorta, GRK2 may be, upon translocation, a key negative regulator of insulin responsiveness and an important regulator of the β-arrestin 2/Akt/eNOS signaling, which is implicated in diabetic endothelial dysfunction.

Remarkably efficient production of a highly insecticidal Chrysodeixis chalcites nucleopolyhedrovirus (ChchNPV) isolate in its homologous host.

PubMed

Bernal, Alexandra; Simón, Oihane; Williams, Trevor; Muñoz, Delia; Caballero, Primitivo

2018-01-03

A Chrysodeixis chalcites nucleopolyhedrovirus from the Canary Islands (ChchNPV-TF1) has proved to be effective for control of Chrysodeixis chalcites on banana crops. Commercialization of this virus as a bioinsecticide requires an efficient production system. The sixth instar (L 6 ) was the most suitable for virus production, producing 1.80 × 10 11 occlusion bodies (OB)/larva and showed a lower prevalence of cannibalism (5.4%) than fourth (L 4 ) or fifth (L 5 ) instars. Inoculation of L 6 at 24 h post molting produced six times more OB (5.72 × 10 11 OB/larva) than recently molted L 6 larvae (1.00 × 10 11 OB/larva). No significant differences were recorded in mean time to death (165-175 h) or OB production per larva (3.75 × 10 11 to 5.97 × 10 11 ) or per mg larval weight (1.30 × 10 11 to 2.11 × 10 9 ), in larvae inoculated with a range of inoculum concentrations (LC 50 -LC 90 ). Groups of infected L 6 larvae reared at a density of 150 larvae/container produced a greater total number of OBs (8.07 × 10 13 OB/container) than lower densities (25, 50 and 100 OB/container), and a similar number to containers with 200 inoculated larvae (8.43 × 10 13 OB/container). The processes described here allow efficient production of sufficient OBs to treat ∼ 40 ha of banana crops using the insects from a single container. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

The VBB SEIS experiment of InSight

NASA Astrophysics Data System (ADS)

De Raucourt, Sebastien; Gabsi, Taoufik; Tanguy, Nebut; Mimoun, David; Lognonne, Philippe; Gagnepain-Beyneix, Jeannine; Banerdt, William; Tillier, Sylvain; Hurst, Kenneth

2012-07-01

SEIS is the core payload of InSight, one of the three missions selected for competitive phase A in the frame of the 2010 Discovery AO. It aims at providing unique observation of the interior structure of Mars and to monitor seismic activity of Mars. SEIS will provide the first seismic model from another planet than Earth. SEIS is an hybrid seismometer composed of 3 SPs and 3 VBBs axes providing ground motion measurement from Dc to 50Hz. A leveling system will ensure the coupling between the ground and the sensors as well as the horizontality of the VBB sphere. This assembly will be deployed on the ground of Mars and will be shielded by a strong thermal insulation and a wind shield. The 24 bits low noise acquisition electronics will remain in the warm electronic box of the lander with the sensors feedback and leveling system electronics. The VBB sphere enclosed three single axis sensors. Those sensors are based on an inverted leaf spring pendulum, which convert ground acceleration into mobile mass displacement. A capacitive displacement sensor monitors this mass displacement to provide a measurement. A force feedback allows transfer function and sensitivity tuning. The VBB sensor has a very strong heritage from previous project and benefits from recent work to improve its performances. Both the mechanical design and the displacement sensors have optimized to improve performances while reducing technological risk and keeping a high TRL. From those development a self-noise well below 10 ^{-9} m.s ^{-2}/sqrt Hz is expected. Environmental sensitivity of SEIS has been minimized by the design of a very efficient wind and thermal shield. Remaining noise is expected to be very close to the VBB self-noise. Associated sources and budget will be discussed. If InSight is selected to fly in 2016, this experiment will provide very high quality seismic signal measurement with a wider bandwidth, higher sensitivity and lower noise than previous Mars seismometer (Viking and Optimism/Mars 96).

Structure of the North Anatolian Fault Zone from the Auto-Correlation of Ambient Seismic Noise Recorded at a Dense Seismometer Array

NASA Astrophysics Data System (ADS)

Taylor, D. G.; Rost, S.; Houseman, G.

2015-12-01

In recent years the technique of cross-correlating the ambient seismic noise wavefield at two seismometers to reconstruct empirical Green's Functions for the determination of Earth structure has been a powerful tool to study the Earth's interior without earthquake or man-made sources. However, far less attention has been paid to using auto-correlations of seismic noise to reveal body wave reflections from interfaces in the subsurface. In principle, the Green's functions thus derived should be comparable to the Earth's impulse response to a co-located source and receiver. We use data from a dense seismic array (Dense Array for Northern Anatolia - DANA) deployed across the northern branch of the North Anatolian Fault Zone (NAFZ) in the region of the 1999 magnitude 7.6 Izmit earthquake in western Turkey. The NAFZ is a major strike-slip system that extends ~1200 km across northern Turkey and continues to pose a high level of seismic hazard, in particular to the mega-city of Istanbul. We construct reflection images for the entire crust and upper mantle over the ~35 km by 70 km footprint of the 70-station DANA array. Using auto-correlations of vertical and horizontal components of ground motion, both P- and S-wave velocity information can be retrieved from the wavefield to constrain crustal structure further to established methods. We show that clear P-wave reflections from the crust-mantle boundary (Moho) can be retrieved using the autocorrelation technique, indicating topography on the Moho on horizontal scales of less than 10 km. Offsets in crustal structure can be identified that seem to be correlated with the surface expression of the fault zone in the region. The combined analysis of auto-correlations using vertical and horizontal components will lead to further insight into the fault zone structure throughout the crust and upper mantle.

Autophagy in osteoblasts is involved in mineralization and bone homeostasis

PubMed Central

Nollet, Marie; Santucci-Darmanin, Sabine; Breuil, Véronique; Al-Sahlanee, Rasha; Cros, Chantal; Topi, Majlinda; Momier, David; Samson, Michel; Pagnotta, Sophie; Cailleteau, Laurence; Battaglia, Séverine; Farlay, Delphine; Dacquin, Romain; Barois, Nicolas; Jurdic, Pierre; Boivin, Georges; Heymann, Dominique; Lafont, Frank; Lu, Shi Shou; Dempster, David W; Carle, Georges F; Pierrefite-Carle, Valérie

2014-01-01

Bone remodeling is a tightly controlled mechanism in which osteoblasts (OB), the cells responsible for bone formation, osteoclasts (OC), the cells specialized for bone resorption, and osteocytes, the multifunctional mechanosensing cells embedded in the bone matrix, are the main actors. Increased oxidative stress in OB, the cells producing and mineralizing bone matrix, has been associated with osteoporosis development but the role of autophagy in OB has not yet been addressed. This is the goal of the present study. We first show that the autophagic process is induced in OB during mineralization. Then, using knockdown of autophagy-essential genes and OB-specific autophagy-deficient mice, we demonstrate that autophagy deficiency reduces mineralization capacity. Moreover, our data suggest that autophagic vacuoles could be used as vehicles in OB to secrete apatite crystals. In addition, autophagy-deficient OB exhibit increased oxidative stress and secretion of the receptor activator of NFKB1 (TNFSF11/RANKL), favoring generation of OC, the cells specialized in bone resorption. In vivo, we observed a 50% reduction in trabecular bone mass in OB-specific autophagy-deficient mice. Taken together, our results show for the first time that autophagy in OB is involved both in the mineralization process and in bone homeostasis. These findings are of importance for mineralized tissues which extend from corals to vertebrates and uncover new therapeutic targets for calcified tissue-related metabolic pathologies. PMID:25484092

Effect of Caloric Restriction and AMPK Activation on Hepatic Nuclear Receptor, Biotransformation Enzyme, and Transporter Expression in Lean and Obese Mice

PubMed Central

Kulkarni, Supriya R.; Xu, Jialin; Donepudi, Ajay C.; Wei, Wei

2014-01-01

Purpose Fatty liver alters liver transporter expression. Caloric restriction (CR), the recommended therapy to reverse fatty liver, increases Sirtuin1 deacetylase activity in liver. This study evaluated whether CR and CR mimetics reversed obesity-induced transporter expression in liver and hepatocytes. Methods mRNA and protein expression was determined in adult lean (lean) and leptin-deficient obese (OB) mice fed ad libitum or placed on 40% (kCal) reduced diet. Hepatocytes were isolated from lean and OB mice, treated with AMP Kinase activators, and gene expression was determined. Results CR decreased Oatp1a1, Oatp1b2, and Abcb11 mRNA expression in lean, but not OB mice. CR increased Abcc2 mRNA OB livers, whereas protein expression increased in both genotypes. CR increased Abcc3 protein expression increased in OB livers. CR did not alter Abcc1, 4 and 5 mRNA expression in lean mice but decreased expression in livers of OB mice. CR increased Abcc4 protein in lean, but not OB mice. Conclusions CR restriction reversed the expression of some, but not all transporters in livers of OB mice. Overall, these data indicate a potential for CR to restore some hepatic transporter changes in OB mice, but suggest a functional leptin axis is needed for reversal of expression for some transporters. PMID:23949303

An Examination of the Ability of Ocean Obervatory Systems to Determine Merchant Ship Direction and Draft

DTIC Science & Technology

2013-09-01

history of ocean measurements and of Ocean Bottom Seismometers in particular. This background will also discuss previous work on beamforming seismic...unsuccessful. The measured bearings changed in a seemingly random fashion despite high signal to noise (SNR). This result is in agreement with other...capabilities increase. One of the types of sensors used in OOSs is the Ocean Bottom Seismometer. These sensors are primarily used to measure

Seismometer using a vertical long natural-period rotational pendulum with magnetic levitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Otake, Yuji; Araya, Akito; Hidano, Kazuo

We have demonstrated a highly sensitive/wideband vertical-component seismometer using an astatic rotational pendulum to obtain a long natural period. This seismometer employs magnetic levitation for removing any parasitic resonances of a spring to support a weight due to gravity and the thermal dependence of the spring constant. The pendulum has a cylindrical plunger-type permanent magnet that has a weight at one side of its end edge. The plunger magnet is inserted into a uniform magnetic field generated by a window-frame-type permanent magnet, and attached to two crossed-leaf spring hinges as a rotational axis outside of the bore of the magnet.more » Magnetic forces applied to the plunger magnet counterbalance the gravitational force at the weight. To realize stable operation of the rotational pendulum without any unnecessary movements of the plunger magnet, a tilt of lines of the magnetic force in the bore of the window-frame magnet was compensated by a tilted magnetic-pole surface near to its opening. The field uniformity reached 10{sup -4} owing to this compensation. The thermal dependence of a magnetic field strength of about 10{sup -3}/K was also compensated by as much as 9x10{sup -5}/K by Ni-Fe metal having a negative permeability coefficient. The metal was attached along the sidewalls of the window-frame magnet. To determine the feedback control parameters for a feedback control seismometer, the natural period of a prototype rotational pendulum was measured. It was more than 8 s, and was able to be changed from 5 to 8 s by using an additional magnetic spring, similar to the voice coil actuator of a speaker. This change was in accordance with theoretical calculations, and showed that the pendulum movement did not include a big nonlinearity caused by the tilt of the lines of the magnetic force. No parasitic resonances were found during experiments. A velocity feedback-control circuit and a capacitance position detector to measure the weight position were applied to the rotational pendulum for building a feedback control seismometer. Observations showed that the noise level of the seismometer was less than about 10{sup -8} m/s at 1 Hz. This fruitful value is close to the specifications of the most sensitive seismometer, such as STS-I. However, low-frequency noise of about 10{sup -7} m/s, caused by a buoyancy change at the pendulum weight arising from atmospheric pressure variation, could be recognized. To decrease the noise, a vacuum chamber to isolate the atmospheric pressure variation should be employed in the next step of the study.« less

Effects of bleach activator, sodium alkyl acyloxybenzene sulfonate, on house dust mites (Dermatophagoides farinae).

PubMed

Tobe, Seiichi; Kamezaki, Hiroki; Watanabe, Toshiyuki; Takaoka, Hiromitsu; Sakaguchi, Masahiro

2010-01-01

House dust mites (Dermatophagoides farinae) in bedding and clothes are a major allergen. However, house dust mites cannot be killed by general washing conditions under 50 degrees C. Therefore, low-temperature washing conditions must be improved to eliminate house dust mites. Sodium alkyl acyloxybenzene sulfonate (OBS) is a bleach activator that is used to intensify the bleaching effects of some laundry products. The purpose of this study was to evaluate the effect of OBS on the elimination of house dust mites in low-temperature washing conditions. D. farinae was soaked in solutions containing different types of OBS for various durations and at various temperatures. The miticidal effects of the various washing conditions were also evaluated for D. farinae. Then sodium lauroyloxybenzene sulfonate (OBS-12) produced the highest D. farinae mortality rate among the OBS solutions that were examined and had a stronger miticidal effect than available chlorine under general washing conditions. OBS exhibited miticidal effects under general washing conditions at low temperatures. Since OBS is already used as an additive in some laundry products to increase the bleaching activity, OBS can be easily used to kill house dust mites under general washing conditions.

Identification of the Relationship between Oil Body Morphology and Oil Content by Microstructure Comparison Combining with QTL Analysis in Brassica napus

PubMed Central

Gu, Jianwei; Chao, Hongbo; Wang, Hao; Li, Yonghong; Li, Dianrong; Xiang, Jun; Gan, Jianping; Lu, Guangyuan; Zhang, Xuekun; Long, Yan; Li, Maoteng

2017-01-01

Oil bodies (OBs) are relatively simple but very important organelles comprising a matrix of triacylglycerol (TAG) surrounded by a phospholipid monolayer embedded and covered with unique proteins. The OB structure in Brassica napus with different oil content and the relationship between the oil content and the OB structure needs to be better understood. In this paper, the characteristics of OBs in the embryo of a series of B. napus materials with different oil content ranging from 34% to over 60% were studied. The results indicated that the OB size was significantly positively correlated with the oil content but was significantly negatively correlated with the glucosinolates and the protein content. Many genes associated with TAG synthesis, OB-membrane proteins, and the cell progress regulatory pathway were identified in the confidence interval of co-located QTLs for oil content, fatty acid (FA) compositions, and protein content. Our results suggested that the morphology of OBs might be directly controlled by the genes associated with OB-membrane proteins and indirectly controlled by the genes associated with TAG synthesis and cell progress regulatory pathway. PMID:28111582

Identification of the Relationship between Oil Body Morphology and Oil Content by Microstructure Comparison Combining with QTL Analysis in Brassica napus.

PubMed

Gu, Jianwei; Chao, Hongbo; Wang, Hao; Li, Yonghong; Li, Dianrong; Xiang, Jun; Gan, Jianping; Lu, Guangyuan; Zhang, Xuekun; Long, Yan; Li, Maoteng

2016-01-01

Oil bodies (OBs) are relatively simple but very important organelles comprising a matrix of triacylglycerol (TAG) surrounded by a phospholipid monolayer embedded and covered with unique proteins. The OB structure in Brassica napus with different oil content and the relationship between the oil content and the OB structure needs to be better understood. In this paper, the characteristics of OBs in the embryo of a series of B. napus materials with different oil content ranging from 34% to over 60% were studied. The results indicated that the OB size was significantly positively correlated with the oil content but was significantly negatively correlated with the glucosinolates and the protein content. Many genes associated with TAG synthesis, OB-membrane proteins, and the cell progress regulatory pathway were identified in the confidence interval of co-located QTLs for oil content, fatty acid (FA) compositions, and protein content. Our results suggested that the morphology of OBs might be directly controlled by the genes associated with OB-membrane proteins and indirectly controlled by the genes associated with TAG synthesis and cell progress regulatory pathway.

Oil body proteins sequentially accumulate throughout seed development in Brassica napus.

PubMed

Jolivet, Pascale; Boulard, Céline; Bellamy, Annick; Valot, Benoît; d'Andréa, Sabine; Zivy, Michel; Nesi, Nathalie; Chardot, Thierry

2011-11-15

Despite the importance of seed oil bodies (OBs) as enclosed compartments for oil storage, little is known about lipid and protein accumulation in OBs during seed formation. OBs from rapeseed (Brassica napus) consist of a triacylglycerol (TAG) core surrounded by a phospholipid monolayer embedded with integral proteins which confer high stability to OBs in the mature dry seed. In the present study, we investigated lipid and protein accumulation patterns throughout seed development (from 5 to 65 days after pollination [DAP]) both in the whole seed and in purified OBs. Deposition of the major proteins (oleosins, caleosins and steroleosins) into OBs was assessed through (i) gene expression pattern, (ii) proteomics analysis, and (iii) protein immunodetection. For the first time, a sequential deposition of integral OB proteins was established. Accumulation of oleosins and caleosins was observed starting from early stages of seed development (12-17 DAP), while steroleosins accumulated later (~25 DAP) onwards. Copyright © 2011 Elsevier GmbH. All rights reserved.

The Puppis region and the last crusade for faint OB stars

NASA Astrophysics Data System (ADS)

Orsatti, Ana M.

1992-08-01

UBV photoelectric and photographic measurements of OB stars from a list of 397 OB stars and 5 early-type supergiants and from the Luminous Stars Survey are presented. The galactic distribution of the OB stars in the region shows concentrations around the open clusters Ruprecht 44 and Ruprecht 55, and the presence of an important grouping of young stars located far below the plane. The distribution in latitude shows that young stars in the region are not restricted to a thin sheet around the plane but are spread over negative latitudes reaching at least b = -5 deg. In longitude, the OB distribution exhibits a concentration of Ob stars in the interval 244-251 deg; this is argued to be due to the presence of the local arm extension.

Seismic monitoring at Deception Island volcano (Antarctica): the 2010-2011 survey

NASA Astrophysics Data System (ADS)

Martín, R.; Carmona, E.; Almendros, J.; Serrano, I.; Villaseñor, A.; Galeano, J.

2012-04-01

As an example of the recent advances introduced in seismic monitoring of Deception Island volcano (Antarctica) during recent years, we describe the instrumental network deployed during the 2010-2011 survey by the Instituto Andaluz de Geofísica of University of Granada, Spain (IAG-UGR). The period of operation extended from December 19, 2010 to March 5, 2011. We deployed a wireless seismic network composed by four three-component seismic stations. These stations are based on 24-bit SL04 SARA dataloggers sampling at 100 sps. They use a PC with embedded linux and SEISLOG data acquisition software. We use two types of three-component seismometers: short-period Mark L4C with natural frequency of 1 Hz and medium-period Lennartz3D/5s with natural frequency of 0.2 Hz. The network was designed for an optimum spatial coverage of the northern half of Deception, where a magma chamber has been reported. Station locations include the vicinity of the Spanish base "Gabriel de Castilla" (GdC), Obsidianas Beach, a zone near the craters from the 1970 eruptions, and the Chilean Shelter located south of Pendulum Cove. Continuous data from the local seismic network are received in real-time in the base by wifi transmission. We used Ubiquiti Networks Nanostation2 antennas with 2.4 GHz, dual-polarity, 10 dBi gain, and 54 Mbps transmission rate. They have shown a great robustness and speed for real-time applications. To prioritize data acquisition when the battery level is low, we have designed a circuit that allows independent power management for the seismic station and wireless transmission system. The reception antenna located at GdC is connected to a computer running SEISCOMP. This software supports several transmission protocols and manages the visualization and recording of seismic data, including the generation of summary plots to show the seismic activity. These twelve data channels are stored in miniseed format and displayed in real time, which allows for a rapid evaluation of the seismic activity and an efficient seismo-volcanic surveillance. The data are processed and analyzed using the SEISAN database management software. In addition to the seismic network, we deployed a small-aperture seismic array south of Fumarole Bay. It is composed by 9 vertical and 1 three-component short-period stations. The 24-bit data acquisition system samples these 12 channels at 100 sps. There is also a permanent seismic station operating since 2008 and located near GdC, that is very useful for the preliminary evaluation of the seismicity at the start of the survey. This station is composed by a 16-s electrolytic seismometer (Eentec SP400) and a 24-bit datalogger (Eentec DR4000) sampling at 100 sps. During the 2010-2011 survey we identified 33 regional earthquakes, 80 volcano-tectonic (VT) earthquakes, and 929 long-period (LP) events. The volcanic alert system has remained green (the lowest level) at all times. The seismic activity has been similar to previous surveys and remained within limits that are normal for the island.

MULTIMERMAID: A dedicated multichannel seismic/weather/zoological float for monitoring of the oceans

NASA Astrophysics Data System (ADS)

Hello, Y. M.; Bonnieux, S.; Joubert, C.; Sukhovich, A.; Argentino, J.; Yegikyan, M.; Nolet, G.

2013-12-01

Delays of seismic P waves are used to make scans or 3D images of the variations in seismic wave speed in the Earth's interior using the techniques of seismic tomography. Observations of such delays are ubiquitous on the continents but rare in oceanic regions, mostly because of the large cost associated with deploying ocean-bottom seismometers. At the same time, several thousand free-drifting profiling floats measure the temperature, salinity and current of the upper 2000 m of the ocean in the Argo program, but are incapable to record and transmit seismic signals. Simons et al. (JGR, 2009) developed the idea to use such floats in order to compensate for the lack of seismic delay observations, especially in the southern hemisphere. We built and tested a prototype of such a seismological sensor using an Apex float from Teledyne Webb Research, a Rafos hydrophone, and electronics developed in collaboration with Osean, a small engineering firm in France. This `MERMAID', for `Mobile Earthquake Recorder in Marine Areas by Independent Divers', has concluded its final design stage and a fleet of 20 units is available for experiments. Since 2012, half of these floats have been deployed in the Mediterranean and in the South Indian Ocean. 10 more will be deployed early in 2014 near the Galapagos islands in the Pacific. Analysis of the first data is allowing us to sharpen the wavelet-based algorithm parameters used to discriminate P-waves from the continuous input signal and adapt it to specific noise conditions. A new multidisciplinary version of Mermaid using a dedicated hydrophone is designed to enlarge the band pass for acoustic signals with much higher frequency than seismic. By combining the same algorithm using wavelet transforms, and by adopting a different monitoring strategy with a dedicated processing, Mermaid is able to continuously analyzes acoustic signals to detect major seismic events, while at the same time regularly checking for weather phenomena such rain, drizzle, open sea and ice, or whale migration. This extension to multi-purpose applications makes the Mermaid very attractive for the Argo program. In fact, Mermaids using passive low cost sensors form a very light and complementary solution that can easily be integrated with an Argo float since CTD data are taken during ascent. Such multidisciplinary approach should allow seismologists to participate in international programs such as Argo and obtain the dense ocean coverage needed to image the deep structure of the Earth. We estimate that about 300 Mermaids, operated over a time span of five years, can provide a ray coverage beneath the oceans comparable to that now available beneath the continents with the Global Seismic Network (GSN). To compensate for the extra energy needed for multidisciplinary applications, Geoazur and Osean are developing a new float, called Multimermaid, that uses the same 17' glass sphere as the Ocean Bottom Seismometers constructed by Geoazur. The Multimermaid can navigate up to a depth of 3000 m and hold 2.5 times more battery power than a conventional float.

What is an Obstetrics/Gynecology Hospitalist?

PubMed

McCue, Brigid

2015-09-01

The obstetrics/gynecology (OB/GYN) hospitalist is the latest subspecialist to evolve from obstetrics and gynecology. Starting in 2002, academic leaders recognized the impact of such coalescing forces as the pressure to reduce maternal morbidity and mortality, stagnant reimbursements and the increasing cost of private practice, the decrease in applications for OB/GYN residencies, and the demand among practicing OB/GYNs for work/life balance. Initially coined laborist, the concept of the OB/GYN hospitalist emerged. Thinking of becoming an OB/GYN hospitalist? Here is what you need to know. Copyright © 2015 Elsevier Inc. All rights reserved.

In obese mice, exercise training increases 11β-HSD1 expression, contributing to glucocorticoid activation and suppression of pulmonary inflammation.

PubMed

Du, Shu-Fang; Yu, Qing; Chuan, Kai; Ye, Chang-Lin; He, Ze-Jia; Liu, Shu-Juan; Zhu, Xiao-Yan; Liu, Yu-Jian

2017-10-01

Exercise training is advocated for treating chronic inflammation and obesity-related metabolic syndromes. Glucocorticoids (GCs), the anti-inflammatory hormones, are synthesized or metabolized in extra-adrenal organs. This study aims to examine whether exercise training affects obesity-associated pulmonary inflammation by regulating local GC synthesis or metabolism. We found that sedentary obese ( ob/ob ) mice exhibited increased levels of interleukin (IL)-1β, IL-18, monocyte chemotactic protein (MCP)-1, and leukocyte infiltration in lung tissues compared with lean mice, which was alleviated by 6 wk of exercise training. Pulmonary corticosterone levels were decreased in ob/ob mice. Exercise training increased pulmonary corticosterone levels in both lean and ob/ob mice. Pulmonary corticosterone levels were negatively correlated with IL-1β, IL-18, and MCP-1. Immunohistochemical staining of the adult mouse lung sections revealed positive immunoreactivities for the steroidogenic acute regulatory protein, the cholesterol side-chain cleavage enzyme (CYP11A1), the steroid 21-hydroxylase (CYP21), 3β-hydroxysteroid dehydrogenase (3β-HSD), and type 1 and type 2 11β-hydroxysteroid dehydrogenase (11β-HSD) but not for 11β-hydroxylase (CYP11B1). Exercise training significantly increased pulmonary 11β-HSD1 expression in both lean and ob/ob mice. In contrast, exercise training per se had no effect on pulmonary 11β-HSD2 expression, although pulmonary 11β-HSD2 levels in ob/ob mice were significantly higher than in lean mice. RU486, a glucocorticoid receptor antagonist, blocked the anti-inflammatory effects of exercise training in lung tissues of obese mice and increased inflammatory cytokines in lean exercised mice. These findings indicate that exercise training increases pulmonary expression of 11β-HSD1, thus contributing to local GC activation and suppression of pulmonary inflammation in obese mice. NEW & NOTEWORTHY Treadmill training leads to a significant increase in pulmonary corticosterone levels in ob/ob mice, which is in parallel with the favorable effects of exercise on obesity-associated pulmonary inflammation. Exercise training increases pulmonary 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) expression but has no significant effect on 11β-HSD2 expression in both lean and ob/ob mice. These findings indicate that exercise training increases pulmonary expression of 11β-HSD1, thus contributing to local glucocorticoid activation and suppression of pulmonary inflammation in obese mice. Copyright © 2017 the American Physiological Society.

Offshore seismicity in the western Marmara Sea, Turkey, revealed by ocean bottom observation

NASA Astrophysics Data System (ADS)

Yamamoto, Yojiro; Takahashi, Narumi; Citak, Seckin; Kalafat, Doǧan; Pinar, Ali; Gürbüz, Cemil; Kaneda, Yoshiyuki

2015-04-01

The North Anatolian Fault (NAF) extends 1600 km westward from a junction with the East Anatolian Fault at the Karliova Triple Junction in eastern Turkey, across northern Turkey and into the Aegean Sea, accommodating about 25 mm/yr of right-lateral motion between Anatolia and the Eurasian plate. Since 1939, devastating earthquakes with magnitude greater than seven ruptured NAF westward, starting from 1939 Erzincan (Ms=7.9) at the eastern Turkey and including the latest 1999 Izmit-Golcuk (Ms=7.7) and the Duzce (Ms=7.4) earthquakes in the Marmara region. Considering the fault segments ruptured by the May 24th, 2014 Northern Aegean earthquake (Mw=6.9), the only un-ruptured segments left behind the 1600 km long NAF locate beneath the Marmara Sea and those segments keep their mystery due to their underwater location. To consider the earthquake hazard and disaster mitigation, the detailed information about fault geometry and its stick-slip behavior beneath the western Marmara Sea is very important. Thus, we started to operate a series of ocean bottom seismographic (OBS) observations to estimate the fault geometry from microearthquake distribution. As a first step, we deployed 3 pop-up type OBSs on 20th of March 2014 as a trial observation, and recovered them on 18th of June 2014. Although one of the OBSs worked only 6 days from the start of the observation, other two OBSs functioned properly during the whole 3-month observation period. We first searched for the microearthquakes missing by the land seismic network and estimated their precious location by using the initial 6 days data, i.e., using all the temporary OBS stations. Although there are only 3 earthquakes listed on the Kandilli Observatory and Earthquake Research Institute (KOERI) catalogue, we could identify 41 earthquakes with more than 5 picking data of P and S first arrivals, and two-third of them located within the OBS network. We found the earthquake cluster along the main NAF and whose depth interval is 12-20 km. This cluster indicates that the dip angle of the main NAF is almost vertical. We also relocated the KOERI-catalogued earthquakes in 3 months periods by combining the land and OBS seismic data. The results indicated that some earthquakes occurred 5-10 km away from the main NAF. Besides, the upper limit of seismicity along NAF seems to dip eastward. To obtain more information of the fault geometry beneath the Marmara Sea, we started a second step observation by using 10 OBSs from September 2014 to June 2015. In addition, we are planning to add 5 OBSs to this observation in Mar. 2015. All OBS observations are conducted as a part of the "Earthquake and Tsunami Disaster Mitigation in the Marmara Region and Disaster Education in Turkey" project, financially supported by Japan International Cooperation Agency (JICA), Japan Science and Technology Agency (JST), and the Ministry of Development in Turkey.

A Characterization of Movement Skills in Obese Children with and without Prader-Willi Syndrome

ERIC Educational Resources Information Center

Lam, Melanie Y.; Rubin, Daniela A.; Duran, Andrea T.; Chavoya, Frank A.; White, Elizabeth; Rose, Debra J.

2016-01-01

Purpose: The aim of this study was twofold: (a) to measure and compare motor proficiency in obese children with Prader-Willi syndrome (OB-PWS) to that in obese children without PWS (OB), and (b) to compare motor proficiency in OB-PWS and OB to normative data. Method: Motor proficiency was measured using the Bruininks-Oseretsky Test of Motor…

Comparative genomic insights into ecophysiology of neutrophilic, microaerophilic iron oxidizing bacteria

DOE PAGES

Kato, Shingo; Ohkuma, Moriya; Powell, Deborah H.; ...

2015-11-13

Neutrophilic microaerophilic iron-oxidizing bacteria (FeOB) are thought to play a significant role in cycling of carbon, iron and associated elements in both freshwater and marine iron-rich environments. However, the roles of the neutrophilic microaerophilic FeOB are still poorly understood due largely to the difficulty of cultivation and lack of functional gene markers. Here, we analyze the genomes of two freshwater neutrophilic microaerophilic stalk-forming FeOB, Ferriphaselus amnicola OYT1 and Ferriphaselus strain R-1. Phylogenetic analyses confirm that these are distinct species within Betaproteobacteria; we describe strain R-1 and propose the name F. globulitus. We compare the genomes to those of two freshwatermore » Betaproteobacterial and three marine Zetaproteobacterial FeOB isolates in order to look for mechanisms common to all FeOB, or just stalk-forming FeOB. The OYT1 and R-1 genomes both contain homologs to cyc2, which encodes a protein that has been shown to oxidize Fe in the acidophilic FeOB, Acidithiobacillus ferrooxidans. This c-type cytochrome common to all seven microaerophilic FeOB isolates, strengthening the case for its common utility in the Fe oxidation pathway. In contrast, the OYT1 and R-1 genomes lack mto genes found in other freshwater FeOB. OYT1 and R-1 both have genes that suggest they can oxidize sulfur species. Both have the genes necessary to fix carbon by the Calvin–Benson– Basshom pathway, while only OYT1 has the genes necessary to fix nitrogen. The stalk-forming FeOB share xag genes that may help form the polysaccharide structure of stalks. Both OYT1 and R-1 make a novel biomineralization structure, short rod-shaped Fe oxyhydroxides much smaller than their stalks; these oxides are constantly shed, and may be a vector for C, P, and metal transport to downstream environments. Lastly, our results show that while different FeOB are adapted to particular niches, freshwater and marine FeOB likely share common mechanisms for Fe oxidation electron transport and biomineralization pathways.« less

Modulation of insulin-like growth factor 1 levels in human osteoarthritic subchondral bone osteoblasts.

PubMed

Massicotte, Frédéric; Fernandes, Julio Cesar; Martel-Pelletier, Johanne; Pelletier, Jean-Pierre; Lajeunesse, Daniel

2006-03-01

Human osteoarthritis (OA) is characterized by cartilage loss, bone sclerosis, osteophyte formation and inflammation of the synovial membrane. We previously reported that OA osteoblasts (Ob) show abnormal phenotypic characteristics possibly responsible for bone sclerosis and that two subgroups of OA patients can be identified by low or high endogenous production of prostaglandin E2 (PGE2) by OA Ob. Here, we determined that the elevated PGE2 levels in the high OA subgroup were linked with enhanced cyclooxygenase-2 (COX-2) protein levels compared to normal and low OA Ob. A linear relationship was observed between endogenous PGE2 levels and insulin-like growth factor 1 (IGF-1) levels in OA Ob. As parathyroid hormone (PTH) and PGE2 are known stimulators of IGF-1 production in Ob, we next evaluated their effect in OA Ob. Both subgroups increased their IGF-1 production similarly in response to PGE2, while the high OA subgroup showed a blunted response to PTH compared to the low OA group. Conversely, only the high OA group showed a significant inhibition of IGF-1 production when PGE2 synthesis was reduced with Naproxen, a non-steroidal antiinflammatory drug (NSAID) that inhibits cyclooxygenases (COX). The PGE2-dependent stimulation of IGF-1 synthesis was due in part to the cAMP/protein kinase A pathway since both the direct inhibition of this pathway with H-89 and the inhibition of EP2 or EP4 receptors, linked to cAMP production, reduced IGF-1 synthesis. The production of the most abundant IGF-1 binding proteins (IGFBPs) in bone tissue, IGFBP-3, -4, and -5, was lower in OA compared to normal Ob independently of the OA group. Under basal condition, OA Ob expressed similar IGF-1 mRNA to normal Ob; however, PGE2 stimulated IGF-1 mRNA expression more in OA than normal Ob. These data suggest that increased IGF-1 levels correlate with elevated endogenous PGE2 levels in OA Ob and that higher IGF-1 levels in OA Ob could be important for bone sclerosis in OA.

Effect of hypothalamic electrolytic lesions in White Leghorn and broiler male cockerels.

PubMed

Arnon, E; Snapir, N; Robinzon, B; Heiblum, R

2004-06-01

1. This study compared the effect of bilateral electrolytic lesions of the basomedial hypothalamus (HL) in broiler and White Leghorn (WL) males. 2. Hypothalamic lesions were placed in WL at 10 weeks of age (body weight 1.1 kg) and in broilers, either at 6 weeks (body weight 1.5kg) or at 10 weeks of age (body weight 3.4kg). They were fed ad libitum until autopsy at 16 and 17 weeks of age for broilers and WL, respectively. 3. Hypothalamic lesions caused obesity (high percentage weight of abdominal adipose tissue) in both strains. Obese fowls with unimpaired reproductive systems were classified as OB and those with functional castration as FC (functionally castrated) or FCLC (functionally castrated with large comb). 4. All post-HL syndromes-OB, FC and FCLC-were present in WL, whereas all obese broilers (which are immature at this age) were classified as OB. 5. The percentage weight of abdominal adipose tissue in OB broilers was lower than in OB WL (3% vs 5%, respectively). 6. Daily food intake of OB broilers was higher than control at 12 to 15 weeks of age, regardless of time of placement of HL, whereas daily food intake of OB WL was significantly higher than that of control WL only during the first 2 weeks following HL. 7. Body weight of OB broilers at autopsy was 20% higher than control broilers, whereas body weight of OB WL was not significantly affected. 8. An additional group of broilers was reared to sexual maturity under food restriction until 28 weeks of age. HL were placed at 10 weeks of age (body weight 1.7 kg). Autopsy was performed after a 4-week period of ad libitum feeding. 9. There were OB as well as FC and FCLC among the HL, food-restricted broilers. Percentage weight of testes and spleen were reduced in OB fowls of both strains, but more so in OB WL. 10. Hyperphagia and weight gain were not observed during the ad libitum feeding period of those obese broilers after HL, indicating that hyperphagia and weight gain are secondary to obesity.

Remote Determination of the in situ Sensitivity of a Streckeisen STS-2 Broadband Seismometer

NASA Astrophysics Data System (ADS)

Uhrhammer, R. A.; Taira, T.; Hellweg, M.

2015-12-01

The sensitivity of a STS-2 broadband seismometer can be determined remotely by two basic methods: 1) via comparison of the inferred ground motions with a reference seismometer, and: 2) via excitation of the calibration coil with a simultaneously recorded stimulus signal. The first method is limited by the accuracy of the reference seismometer and the second method is limited by the accuracy of the motor constant (Gc) of the calibration coil. The accuracy of both methods is also influenced by the signal-to-noise ratio (SNR) in the presence of background seismic noise and the degree of orthogonality of the tri-axial suspension in the STS-2 seismometer. The Streckeisen STS-2 manual states that the signal coil sensitivity (Gs) is 1500 V/(m/s) (+/-1.5%) and it gives Gc to only one decimal place (ie, Gc = 2 g/A). Unfortunately the factory Gc value is not given with sufficient accuracy to be useful for determining the sensitivity of Gs to within 1.5%. Thus we need to determine Gc to enable accurate calibration of the STS-2 via remote excitation of the Gc with a known stimulus. The Berkeley Digital Seismic Network (BDSN) has 12 STS-2 seismometers with co-sited reference sensors (strong motion accelerometers) and they are all recorded by Q330HR data loggers with factory cabling. The procedure is to first verify the sensitivity of the STS-2 signal coils (Gs) via comparison of the ground motions recorded by the STS-2 with the ground motions recorded by the co-sited strong motion accelerometer for an earthquake with has sufficiently high SNR in a passband common to both sensors. The second step in the procedure is to remotely (from Berkeley) excite to calibration coil with a 1 Hz sinusoid which is simultaneously recorded and, using the above measured Gs values, solve for Gc of the calibration coils. The resulting Gc values are typically 2.20-2.50 g/A (accurate to 3+ decimal places) and once the Gc values are found, the STS-2 absolute sensitivity can be determined remotely to an accuracy of better than 1%. The primary advantage of using strong motion accelerometers as the reference instrument is that their absolute calibration can be checked via tilt tests if the need arises.

Results From a Borehole Seismometer Array I: Microseismicity at a Productive Geothermal Field, Kilauea Lower East Rift Zone, Puna, Hawaii

NASA Astrophysics Data System (ADS)

Kenedi, C. L.; Shalev, E.; Malin, P.; Kaleikini, M.; Dahl, G.

2008-12-01

Borehole seismometer arrays have proven successful in both the exploration and monitoring of geothermal fields. Because the seismometers are located at depth, they are isolated from human noise and record microearthquakes with clearly identifiable seismic phases that can be used for event location. Further analysis of these events can be used to resolve earthquake clouds into identifiable faults. The local fault and dike structures in Puna, in southeastern Hawaii, are of interest both in terms of electricity production and volcanic hazard monitoring. The geothermal power plant at Puna has a 30MW capacity and is built on a section of the Kilauea Lower East Rift Zone where lava flows erupted as recently as 1955. In order to improve seismic monitoring in this area, we installed eight 3-component borehole seismometers. The instrument depths range from 24 to 210 m (80 to 690 ft); the shallower instruments have 2 Hz geophones and the deepest have 4.5 Hz geophones. The seismometers are located at the vertices of two rhombs, 2 km wide x 4 km long and 4 km wide x 8 km long, both centered at the power plant. Since June 2006, we have located >4500 earthquakes; P- and S-wave arrivals were hand picked and events located using Hypoinverse-2000. Most of the earthquakes occurred at depths between 2.5 and 3 km. The large majority of events were M-0.5 to M0.5; the Gutenberg-Richter b-value is 1.4, which is consistent with microearthquake swarms. Frequency analysis indicates a 7-day periodicity; a Schuster diagram confirms increased seismicity on a weekly cycle. The location, depth, and period of the microearthquakes suggest that power plant activity affects local seismicity. Southwest of the geothermal facility, up-rift towards the Kilauea summit, earthquakes were progressively deeper at greater distances. Depths also increased towards the south, which is consistent with the eastern extension of the south-dipping, east-striking Hilina fault system. To the northeast, down-rift of the array, there is a sudden cessation of seismicity not accounted for by known geologic structures. This borehole seismometer network is providing essential data for the detailed characterization of the Kilauea Lower East Rift Zone and the Puna geothermal field.

Functional imaging of cortical feedback projections to the olfactory bulb

PubMed Central

Rothermel, Markus; Wachowiak, Matt

2014-01-01

Processing of sensory information is substantially shaped by centrifugal, or feedback, projections from higher cortical areas, yet the functional properties of these projections are poorly characterized. Here, we used genetically-encoded calcium sensors (GCaMPs) to functionally image activation of centrifugal projections targeting the olfactory bulb (OB). The OB receives massive centrifugal input from cortical areas but there has been as yet no characterization of their activity in vivo. We focused on projections to the OB from the anterior olfactory nucleus (AON), a major source of cortical feedback to the OB. We expressed GCaMP selectively in AON projection neurons using a mouse line expressing Cre recombinase (Cre) in these neurons and Cre-dependent viral vectors injected into AON, allowing us to image GCaMP fluorescence signals from their axon terminals in the OB. Electrical stimulation of AON evoked large fluorescence signals that could be imaged from the dorsal OB surface in vivo. Surprisingly, odorants also evoked large signals that were transient and coupled to odorant inhalation both in the anesthetized and awake mouse, suggesting that feedback from AON to the OB is rapid and robust across different brain states. The strength of AON feedback signals increased during wakefulness, suggesting a state-dependent modulation of cortical feedback to the OB. Two-photon GCaMP imaging revealed that different odorants activated different subsets of centrifugal AON axons and could elicit both excitation and suppression in different axons, indicating a surprising richness in the representation of odor information by cortical feedback to the OB. Finally, we found that activating neuromodulatory centers such as basal forebrain drove AON inputs to the OB independent of odorant stimulation. Our results point to the AON as a multifunctional cortical area that provides ongoing feedback to the OB and also serves as a descending relay for other neuromodulatory systems. PMID:25071454

Clinical Variability in Cardiovascular Disease Risk Factor Screening and Management in Adolescent and Young Adult Women with Polycystic Ovary Syndrome.

PubMed

Baer, Tamara E; Milliren, Carly E; Walls, Courtney; DiVasta, Amy D

2015-10-01

To review the clinical presentation, evaluation, and management of normal-weight (NW), overweight (OW), and obese (OB) adolescent and young adult women with polycystic ovary syndrome (PCOS) during a 2-year follow-up. Retrospective chart review. One hundred seventy-three adolescent and young adult women, aged 12-22 years, diagnosed with PCOS. Demographic, health data, and laboratory measures were abstracted from 3 clinic visits: baseline and 1- and 2-year follow-up. Subjects were classified as NW, OW, or OB. Longitudinal data were analyzed using repeated-measures analysis of variance. Body mass index, self-reported concerns, and lifestyle changes. Most patients (73%) were OW or OB. Family history of type 2 diabetes was greater in OW (38%) and OB (53%) patients compared with NW (22%) patients (P = .002). Acanthosis nigricans was identified in OW (62%) and OB (21%) patients but not in NW patients (0%; P < .001). OW and OB patients had higher fasting insulin (P < .001) and lower high-density lipoprotein cholesterol (P = .005) levels than NW patients, although screening rates were low. Body mass index Z-scores decreased in both OW and OB patients over time (0.07 unit/yr, P < .001). Most patients with PCOS were OW or OB. Substantial clinical variability existed in cardiovascular disease (CVD) screening; among those screened, OW and OB patients had greater CVD risk factors. Despite self-reported concerns about weight and diabetes risk among OW and OB patients, no clinically significant change in body mass index percentile occurred. Evidence-based interventions and recommendations for screening tests are needed to address CVD risk in adolescents and young adults with PCOS. Copyright © 2015 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

Tumour necrosis factor-α inhibition with lenalidomide alleviates tissue oxidative injury and apoptosis in ob/ob obese mice.

PubMed

Zhu, Xiaoling; Jiang, Shasha; Hu, Nan; Luo, Fuling; Dong, Hailong; Kang, Yu-Ming; Jones, Kyla R; Zou, Yunzeng; Xiong, Lize; Ren, Jun

2014-07-01

Lenalidomide (Revlimid; Selleck Chemicals, Houston, TX, USA), an analogue of thalidomide, possesses potent cytokine modulatory capacity through inhibition of cytokines such as tumour necrosis factor (TNF)-α, a cytokine pivotal for the onset and development of complications in obesity and diabetes mellitus. The present study was designed to evaluate the effect of lenalidomide on oxidative stress, protein and DNA damage in multiple organs in an ob/ob murine model of obesity. To this end, C57BL/6 lean and ob/ob obese mice were administered lenalidomide (50 mg/kg per day, p.o.) for 5 days. Oxidative stress, protein and DNA damage were assessed using the conversion of reduced glutathione (GSH) to oxidized glutathione (GSSG), carbonyl formation and Comet assay, respectively. Apoptosis was evaluated using caspase 3 activity, and levels of Bax, Bcl-2, Bip, caspase 8, caspase 9 and TNF-α were assessed using western blot analysis. Lenalidomide treatment did not affect glucose clearance in lean or ob/ob mice. Obese mice exhibited a reduced GSH/GSSG ratio in the liver, gastrocnemius skeletal muscle and small intestine, as well as enhanced protein carbonyl formation, DNA damage and caspase 3 activity in the liver, kidney, skeletal muscle and intestine; these effects were alleviated by lenalidomide, with the exception of obesity-associated DNA damage in the liver and kidney. Western blot analysis revealed elevated TNF-α, Bax, Bcl-2, Bip, caspase 8 and caspase 9 in ob/ob mice with various degrees of reversal by lenalidomide treatment. Together, these data indicate that lenalidomide protects against obesity-induced tissue injury and protein damage, possibly in association with antagonism of cytokine production and cytokine-induced apoptosis and oxidative stress. © 2014 Wiley Publishing Asia Pty Ltd.