A Web-GIS Procedure Based on Satellite Multi-Spectral and Airborne LIDAR Data to Map the Road blockage Due to seismic Damages of Built-Up Urban Areas

NASA Astrophysics Data System (ADS)

Costanzo, Antonio; Montuori, Antonio; Silva, Juan Pablo; Silvestri, Malvina; Musacchio, Massimo; Buongiorno, Maria Fabrizia; Stramondo, Salvatore

2016-08-01

In this work, a web-GIS procedure to map the risk of road blockage in urban environments through the combined use of space-borne and airborne remote sensing sensors is presented. The methodology concerns (1) the provision of a geo-database through the integration of space-borne multispectral images and airborne LiDAR data products; (2) the modeling of building vulnerability, based on the corresponding 3D geometry and construction time information; (3) the GIS-based mapping of road closure due to seismic- related building collapses based on the building characteristic height and the width of the road. Experimental results, gathered for the Cosenza urban area, allow demonstrating the benefits of both the proposed approach and the GIS-based integration of multi-platforms remote sensing sensors and techniques for seismic road assessment purposes.

Seismic Hazard Maps for Seattle, Washington, Incorporating 3D Sedimentary Basin Effects, Nonlinear Site Response, and Rupture Directivity

USGS Publications Warehouse

Frankel, Arthur D.; Stephenson, William J.; Carver, David L.; Williams, Robert A.; Odum, Jack K.; Rhea, Susan

2007-01-01

This report presents probabilistic seismic hazard maps for Seattle, Washington, based on over 500 3D simulations of ground motions from scenario earthquakes. These maps include 3D sedimentary basin effects and rupture directivity. Nonlinear site response for soft-soil sites of fill and alluvium was also applied in the maps. The report describes the methodology for incorporating source and site dependent amplification factors into a probabilistic seismic hazard calculation. 3D simulations were conducted for the various earthquake sources that can affect Seattle: Seattle fault zone, Cascadia subduction zone, South Whidbey Island fault, and background shallow and deep earthquakes. The maps presented in this document used essentially the same set of faults and distributed-earthquake sources as in the 2002 national seismic hazard maps. The 3D velocity model utilized in the simulations was validated by modeling the amplitudes and waveforms of observed seismograms from five earthquakes in the region, including the 2001 M6.8 Nisqually earthquake. The probabilistic seismic hazard maps presented here depict 1 Hz response spectral accelerations with 10%, 5%, and 2% probabilities of exceedance in 50 years. The maps are based on determinations of seismic hazard for 7236 sites with a spacing of 280 m. The maps show that the most hazardous locations for this frequency band (around 1 Hz) are soft-soil sites (fill and alluvium) within the Seattle basin and along the inferred trace of the frontal fault of the Seattle fault zone. The next highest hazard is typically found for soft-soil sites in the Duwamish Valley south of the Seattle basin. In general, stiff-soil sites in the Seattle basin exhibit higher hazard than stiff-soil sites outside the basin. Sites with shallow bedrock outside the Seattle basin have the lowest estimated hazard for this frequency band.

Bayesian Estimation of the Spatially Varying Completeness Magnitude of Earthquake Catalogs

NASA Astrophysics Data System (ADS)

Mignan, A.; Werner, M.; Wiemer, S.; Chen, C.; Wu, Y.

2010-12-01

Assessing the completeness magnitude Mc of earthquake catalogs is an essential prerequisite for any seismicity analysis. We employ a simple model to compute Mc in space, based on the proximity to seismic stations in a network. We show that a relationship of the form Mcpred(d) = ad^b+c, with d the distance to the 5th nearest seismic station, fits the observations well. We then propose a new Mc mapping approach, the Bayesian Magnitude of Completeness (BMC) method, based on a 2-step procedure: (1) a spatial resolution optimization to minimize spatial heterogeneities and uncertainties in Mc estimates and (2) a Bayesian approach that merges prior information about Mc based on the proximity to seismic stations with locally observed values weighted by their respective uncertainties. This new methodology eliminates most weaknesses associated with current Mc mapping procedures: the radius that defines which earthquakes to include in the local magnitude distribution is chosen according to an objective criterion and there are no gaps in the spatial estimation of Mc. The method solely requires the coordinates of seismic stations. Here, we investigate the Taiwan Central Weather Bureau (CWB) earthquake catalog by computing a Mc map for the period 1994-2010.

Geodesy- and geology-based slip-rate models for the Western United States (excluding California) national seismic hazard maps

USGS Publications Warehouse

Petersen, Mark D.; Zeng, Yuehua; Haller, Kathleen M.; McCaffrey, Robert; Hammond, William C.; Bird, Peter; Moschetti, Morgan; Shen, Zhengkang; Bormann, Jayne; Thatcher, Wayne

2014-01-01

The 2014 National Seismic Hazard Maps for the conterminous United States incorporate additional uncertainty in fault slip-rate parameter that controls the earthquake-activity rates than was applied in previous versions of the hazard maps. This additional uncertainty is accounted for by new geodesy- and geology-based slip-rate models for the Western United States. Models that were considered include an updated geologic model based on expert opinion and four combined inversion models informed by both geologic and geodetic input. The two block models considered indicate significantly higher slip rates than the expert opinion and the two fault-based combined inversion models. For the hazard maps, we apply 20 percent weight with equal weighting for the two fault-based models. Off-fault geodetic-based models were not considered in this version of the maps. Resulting changes to the hazard maps are generally less than 0.05 g (acceleration of gravity). Future research will improve the maps and interpret differences between the new models.

Challenges in making a seismic hazard map for Alaska and the Aleutians

USGS Publications Warehouse

Wesson, R.L.; Boyd, O.S.; Mueller, C.S.; Frankel, A.D.; Freymueller, J.T.

2008-01-01

We present a summary of the data and analyses leading to the revision of the time-independent probabilistic seismic hazard maps of Alaska and the Aleutians. These maps represent a revision of existing maps based on newly obtained data, and reflect best current judgments about methodology and approach. They have been prepared following the procedures and assumptions made in the preparation of the 2002 National Seismic Hazard Maps for the lower 48 States, and will be proposed for adoption in future revisions to the International Building Code. We present example maps for peak ground acceleration, 0.2 s spectral amplitude (SA), and 1.0 s SA at a probability level of 2% in 50 years (annual probability of 0.000404). In this summary, we emphasize issues encountered in preparation of the maps that motivate or require future investigation and research.

Bedrock topography of western Cape Cod, Massachusetts, based on bedrock altitudes from geologic borings and analysis of ambient seismic noise by the horizontal-to-vertical spectral-ratio method

USGS Publications Warehouse

Fairchild, Gillian M.; Lane, John W.; Voytek, Emily B.; LeBlanc, Denis R.

2013-01-01

This report presents a topographic map of the bedrock surface beneath western Cape Cod, Massachusetts, that was prepared for use in groundwater-flow models of the Sagamore lens of the Cape Cod aquifer. The bedrock surface of western Cape Cod had been characterized previously through seismic refraction surveys and borings drilled to bedrock. The borings were mostly on and near the Massachusetts Military Reservation (MMR). The bedrock surface was first mapped by Oldale (1969), and mapping was updated in 2006 by the Air Force Center for Environmental Excellence (AFCEE, 2006). This report updates the bedrock-surface map with new data points collected by using a passive seismic technique based on the horizontal-to-vertical spectral ratio (HVSR) of ambient seismic noise (Lane and others, 2008) and from borings drilled to bedrock since the 2006 map was prepared. The HVSR method is based on a relationship between the resonance frequency of ambient seismic noise as measured at land surface and the thickness of the unconsolidated sediments that overlie consolidated bedrock. The HVSR method was shown by Lane and others (2008) to be an effective method for determining sediment thickness on Cape Cod owing to the distinct difference in the acoustic impedance between the sediments and the underlying bedrock. The HVSR data for 164 sites were combined with data from 559 borings to bedrock in the study area to create a spatially distributed dataset that was manually contoured to prepare a topographic map of the bedrock surface. The interpreted bedrock surface generally slopes downward to the southeast as was shown on the earlier maps by Oldale (1969) and AFCEE (2006). The surface also has complex small-scale topography characteristic of a glacially eroded surface. More information about the methods used to prepare the map is given in the pamphlet that accompanies this plate.

Investigating the complex structural integrity of the Zeit Bay Field, Gulf of Suez, Egypt, using interpretation of 3D seismic reflection data

NASA Astrophysics Data System (ADS)

Afife, M.; Salem, M.; Aziz, M. Abdel

2017-07-01

Zeit Bay Field is one of the most important oil-bearing fields in the Gulf of Suez, Egypt, producing oil from the fractured basement rocks. Due to the complex structural setting of the area and the classical exploration concept that was based mainly on 2D seismic survey data, the area suffered from limited hydrocarbon interest for several years. During this time, most of the drilled wells hit structural highs and resulted in several dry holes. The present study is based on the interpretation of more recently acquired 3D seismic survey data as, matched with the available well logs, used to understand the complex structural setting of the Zeit Bay Field and provide insight into the entrapment style of the implied hydrocarbons. Several selected seismic cross sections were constructed, to extract subsurface geologic information, using available seismic profiles and wells. In addition, structure contour maps (isochronous maps, converted to depth maps) were constructed for the peaks of the basement, Nubian Sandstone, Kareem and Belayim Formations. Folds (anticlines and synclines) and faults (dip-slip) are identified on these maps, both individually and in groups, giving rise to step-like belts, as well as graben and horst blocks.

Evaluation of potential surface rupture and review of current seismic hazards program at the Los Alamos National Laboratory. Final report

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

Not Available

1991-12-09

This report summarizes the authors review and evaluation of the existing seismic hazards program at Los Alamos National Laboratory (LANL). The report recommends that the original program be augmented with a probabilistic analysis of seismic hazards involving assignment of weighted probabilities of occurrence to all potential sources. This approach yields a more realistic evaluation of the likelihood of large earthquake occurrence particularly in regions where seismic sources may have recurrent intervals of several thousand years or more. The report reviews the locations and geomorphic expressions of identified fault lines along with the known displacements of these faults and last knowmore » occurrence of seismic activity. Faults are mapped and categorized into by their potential for actual movement. Based on geologic site characterization, recommendations are made for increased seismic monitoring; age-dating studies of faults and geomorphic features; increased use of remote sensing and aerial photography for surface mapping of faults; the development of a landslide susceptibility map; and to develop seismic design standards for all existing and proposed facilities at LANL.« less

Revision of Time-Independent Probabilistic Seismic Hazard Maps for Alaska

USGS Publications Warehouse

Wesson, Robert L.; Boyd, Oliver S.; Mueller, Charles S.; Bufe, Charles G.; Frankel, Arthur D.; Petersen, Mark D.

2007-01-01

We present here time-independent probabilistic seismic hazard maps of Alaska and the Aleutians for peak ground acceleration (PGA) and 0.1, 0.2, 0.3, 0.5, 1.0 and 2.0 second spectral acceleration at probability levels of 2 percent in 50 years (annual probability of 0.000404), 5 percent in 50 years (annual probability of 0.001026) and 10 percent in 50 years (annual probability of 0.0021). These maps represent a revision of existing maps based on newly obtained data and assumptions reflecting best current judgments about methodology and approach. These maps have been prepared following the procedures and assumptions made in the preparation of the 2002 National Seismic Hazard Maps for the lower 48 States. A significant improvement relative to the 2002 methodology is the ability to include variable slip rate along a fault where appropriate. These maps incorporate new data, the responses to comments received at workshops held in Fairbanks and Anchorage, Alaska, in May, 2005, and comments received after draft maps were posted on the National Seismic Hazard Mapping Web Site. These maps will be proposed for adoption in future revisions to the International Building Code. In this documentation we describe the maps and in particular explain and justify changes that have been made relative to the 1999 maps. We are also preparing a series of experimental maps of time-dependent hazard that will be described in future documents.

USGS National Seismic Hazard Maps

USGS Publications Warehouse

Frankel, A.D.; Mueller, C.S.; Barnhard, T.P.; Leyendecker, E.V.; Wesson, R.L.; Harmsen, S.C.; Klein, F.W.; Perkins, D.M.; Dickman, N.C.; Hanson, S.L.; Hopper, M.G.

2000-01-01

The U.S. Geological Survey (USGS) recently completed new probabilistic seismic hazard maps for the United States, including Alaska and Hawaii. These hazard maps form the basis of the probabilistic component of the design maps used in the 1997 edition of the NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures, prepared by the Building Seismic Safety Council arid published by FEMA. The hazard maps depict peak horizontal ground acceleration and spectral response at 0.2, 0.3, and 1.0 sec periods, with 10%, 5%, and 2% probabilities of exceedance in 50 years, corresponding to return times of about 500, 1000, and 2500 years, respectively. In this paper we outline the methodology used to construct the hazard maps. There are three basic components to the maps. First, we use spatially smoothed historic seismicity as one portion of the hazard calculation. In this model, we apply the general observation that moderate and large earthquakes tend to occur near areas of previous small or moderate events, with some notable exceptions. Second, we consider large background source zones based on broad geologic criteria to quantify hazard in areas with little or no historic seismicity, but with the potential for generating large events. Third, we include the hazard from specific fault sources. We use about 450 faults in the western United States (WUS) and derive recurrence times from either geologic slip rates or the dating of pre-historic earthquakes from trenching of faults or other paleoseismic methods. Recurrence estimates for large earthquakes in New Madrid and Charleston, South Carolina, were taken from recent paleoliquefaction studies. We used logic trees to incorporate different seismicity models, fault recurrence models, Cascadia great earthquake scenarios, and ground-motion attenuation relations. We present disaggregation plots showing the contribution to hazard at four cities from potential earthquakes with various magnitudes and distances.

Maps Showing Seismic Landslide Hazards in Anchorage, Alaska

USGS Publications Warehouse

Jibson, Randall W.; Michael, John A.

2009-01-01

The devastating landslides that accompanied the great 1964 Alaska earthquake showed that seismically triggered landslides are one of the greatest geologic hazards in Anchorage. Maps quantifying seismic landslide hazards are therefore important for planning, zoning, and emergency-response preparation. The accompanying maps portray seismic landslide hazards for the following conditions: (1) deep, translational landslides, which occur only during great subduction-zone earthquakes that have return periods of =~300-900 yr; (2) shallow landslides for a peak ground acceleration (PGA) of 0.69 g, which has a return period of 2,475 yr, or a 2 percent probability of exceedance in 50 yr; and (3) shallow landslides for a PGA of 0.43 g, which has a return period of 475 yr, or a 10 percent probability of exceedance in 50 yr. Deep, translational landslide hazard zones were delineated based on previous studies of such landslides, with some modifications based on field observations of locations of deep landslides. Shallow-landslide hazards were delineated using a Newmark-type displacement analysis for the two probabilistic ground motions modeled.

Maps showing seismic landslide hazards in Anchorage, Alaska

USGS Publications Warehouse

Jibson, Randall W.

2014-01-01

The devastating landslides that accompanied the great 1964 Alaska earthquake showed that seismically triggered landslides are one of the greatest geologic hazards in Anchorage. Maps quantifying seismic landslide hazards are therefore important for planning, zoning, and emergency-response preparation. The accompanying maps portray seismic landslide hazards for the following conditions: (1) deep, translational landslides, which occur only during great subduction-zone earthquakes that have return periods of =300-900 yr; (2) shallow landslides for a peak ground acceleration (PGA) of 0.69 g, which has a return period of 2,475 yr, or a 2 percent probability of exceedance in 50 yr; and (3) shallow landslides for a PGA of 0.43 g, which has a return period of 475 yr, or a 10 percent probability of exceedance in 50 yr. Deep, translational landslide hazards were delineated based on previous studies of such landslides, with some modifications based on field observations of locations of deep landslides. Shallow-landslide hazards were delineated using a Newmark-type displacement analysis for the two probabilistic ground motions modeled.

Re-evaluation and updating of the seismic hazard of Lebanon

NASA Astrophysics Data System (ADS)

Huijer, Carla; Harajli, Mohamed; Sadek, Salah

2016-01-01

This paper presents the results of a study undertaken to evaluate the implications of the newly mapped offshore Mount Lebanon Thrust (MLT) fault system on the seismic hazard of Lebanon and the current seismic zoning and design parameters used by the local engineering community. This re-evaluation is critical, given that the MLT is located at close proximity to the major cities and economic centers of the country. The updated seismic hazard was assessed using probabilistic methods of analysis. The potential sources of seismic activities that affect Lebanon were integrated along with any/all newly established characteristics within an updated database which includes the newly mapped fault system. The earthquake recurrence relationships of these sources were developed from instrumental seismology data, historical records, and earlier studies undertaken to evaluate the seismic hazard of neighboring countries. Maps of peak ground acceleration contours, based on 10 % probability of exceedance in 50 years (as per Uniform Building Code (UBC) 1997), as well as 0.2 and 1 s peak spectral acceleration contours, based on 2 % probability of exceedance in 50 years (as per International Building Code (IBC) 2012), were also developed. Finally, spectral charts for the main coastal cities of Beirut, Tripoli, Jounieh, Byblos, Saida, and Tyre are provided for use by designers.

Toward uniform probabilistic seismic hazard assessments for Southeast Asia

NASA Astrophysics Data System (ADS)

Chan, C. H.; Wang, Y.; Shi, X.; Ornthammarath, T.; Warnitchai, P.; Kosuwan, S.; Thant, M.; Nguyen, P. H.; Nguyen, L. M.; Solidum, R., Jr.; Irsyam, M.; Hidayati, S.; Sieh, K.

2017-12-01

Although most Southeast Asian countries have seismic hazard maps, various methodologies and quality result in appreciable mismatches at national boundaries. We aim to conduct a uniform assessment across the region by through standardized earthquake and fault databases, ground-shaking scenarios, and regional hazard maps. Our earthquake database contains earthquake parameters obtained from global and national seismic networks, harmonized by removal of duplicate events and the use of moment magnitude. Our active-fault database includes fault parameters from previous studies and from the databases implemented for national seismic hazard maps. Another crucial input for seismic hazard assessment is proper evaluation of ground-shaking attenuation. Since few ground-motion prediction equations (GMPEs) have used local observations from this region, we evaluated attenuation by comparison of instrumental observations and felt intensities for recent earthquakes with predicted ground shaking from published GMPEs. We then utilize the best-fitting GMPEs and site conditions into our seismic hazard assessments. Based on the database and proper GMPEs, we have constructed regional probabilistic seismic hazard maps. The assessment shows highest seismic hazard levels near those faults with high slip rates, including the Sagaing Fault in central Myanmar, the Sumatran Fault in Sumatra, the Palu-Koro, Matano and Lawanopo Faults in Sulawesi, and the Philippine Fault across several islands of the Philippines. In addition, our assessment demonstrates the important fact that regions with low earthquake probability may well have a higher aggregate probability of future earthquakes, since they encompass much larger areas than the areas of high probability. The significant irony then is that in areas of low to moderate probability, where building codes are usually to provide less seismic resilience, seismic risk is likely to be greater. Infrastructural damage in East Malaysia during the 2015 Sabah earthquake offers a case in point.

Seismic slope-performance analysis: from hazard map to decision support system

USGS Publications Warehouse

Miles, Scott B.; Keefer, David K.; Ho, Carlton L.

1999-01-01

In response to the growing recognition of engineers and decision-makers of the regional effects of earthquake-induced landslides, this paper presents a general approach to conducting seismic landslide zonation, based on the popular Newmark's sliding block analogy for modeling coherent landslides. Four existing models based on the sliding block analogy are compared. The comparison shows that the models forecast notably different levels of slope performance. Considering this discrepancy along with the limitations of static maps as a decision tool, a spatial decision support system (SDSS) for seismic landslide analysis is proposed, which will support investigations over multiple scales for any number of earthquake scenarios and input conditions. Most importantly, the SDSS will allow use of any seismic landslide analysis model and zonation approach. Developments associated with the SDSS will produce an object-oriented model for encapsulating spatial data, an object-oriented specification to allow construction of models using modular objects, and a direct-manipulation, dynamic user-interface that adapts to the particular seismic landslide model configuration.

Seismic hazard in the Nation's breadbasket

USGS Publications Warehouse

Boyd, Oliver; Haller, Kathleen; Luco, Nicolas; Moschetti, Morgan P.; Mueller, Charles; Petersen, Mark D.; Rezaeian, Sanaz; Rubinstein, Justin L.

2015-01-01

The USGS National Seismic Hazard Maps were updated in 2014 and included several important changes for the central United States (CUS). Background seismicity sources were improved using a new moment-magnitude-based catalog; a new adaptive, nearest-neighbor smoothing kernel was implemented; and maximum magnitudes for background sources were updated. Areal source zones developed by the Central and Eastern United States Seismic Source Characterization for Nuclear Facilities project were simplified and adopted. The weighting scheme for ground motion models was updated, giving more weight to models with a faster attenuation with distance compared to the previous maps. Overall, hazard changes (2% probability of exceedance in 50 years, across a range of ground-motion frequencies) were smaller than 10% in most of the CUS relative to the 2008 USGS maps despite new ground motion models and their assigned logic tree weights that reduced the probabilistic ground motions by 5–20%.

Documentation for Initial Seismic Hazard Maps for Haiti

USGS Publications Warehouse

Frankel, Arthur; Harmsen, Stephen; Mueller, Charles; Calais, Eric; Haase, Jennifer

2010-01-01

In response to the urgent need for earthquake-hazard information after the tragic disaster caused by the moment magnitude (M) 7.0 January 12, 2010, earthquake, we have constructed initial probabilistic seismic hazard maps for Haiti. These maps are based on the current information we have on fault slip rates and historical and instrumental seismicity. These initial maps will be revised and improved as more data become available. In the short term, more extensive logic trees will be developed to better capture the uncertainty in key parameters. In the longer term, we will incorporate new information on fault parameters and previous large earthquakes obtained from geologic fieldwork. These seismic hazard maps are important for the management of the current crisis and the development of building codes and standards for the rebuilding effort. The boundary between the Caribbean and North American Plates in the Hispaniola region is a complex zone of deformation. The highly oblique ~20 mm/yr convergence between the two plates (DeMets and others, 2000) is partitioned between subduction zones off of the northern and southeastern coasts of Hispaniola and strike-slip faults that transect the northern and southern portions of the island. There are also thrust faults within the island that reflect the compressional component of motion caused by the geometry of the plate boundary. We follow the general methodology developed for the 1996 U.S. national seismic hazard maps and also as implemented in the 2002 and 2008 updates. This procedure consists of adding the seismic hazard calculated from crustal faults, subduction zones, and spatially smoothed seismicity for shallow earthquakes and Wadati-Benioff-zone earthquakes. Each one of these source classes will be described below. The lack of information on faults in Haiti requires many assumptions to be made. These assumptions will need to be revisited and reevaluated as more fieldwork and research are accomplished. We made two sets of maps using different assumptions about site conditions. One set of maps is for a firm-rock site condition (30-m averaged shear-wave velocity, Vs30, of 760 m/s). We also developed hazard maps that contain site amplification based on a grid of Vs30 values estimated from topographic slope. These maps take into account amplification from soils. We stress that these new maps are designed to quantify the hazard for Haiti; they do not consider all the sources of earthquake hazard that affect the Dominican Republic and therefore should not be considered as complete hazard maps for eastern Hispaniola. For example, we have not included hazard from earthquakes in the Mona Passage nor from large earthquakes on the subduction zone interface north of Puerto Rico. Furthermore, they do not capture all the earthquake hazards for eastern Cuba.

A Framework for the Validation of Probabilistic Seismic Hazard Analysis Maps Using Strong Ground Motion Data

NASA Astrophysics Data System (ADS)

Bydlon, S. A.; Beroza, G. C.

2015-12-01

Recent debate on the efficacy of Probabilistic Seismic Hazard Analysis (PSHA), and the utility of hazard maps (i.e. Stein et al., 2011; Hanks et al., 2012), has prompted a need for validation of such maps using recorded strong ground motion data. Unfortunately, strong motion records are limited spatially and temporally relative to the area and time windows hazard maps encompass. We develop a framework to test the predictive powers of PSHA maps that is flexible with respect to a map's specified probability of exceedance and time window, and the strong motion receiver coverage. Using a combination of recorded and interpolated strong motion records produced through the ShakeMap environment, we compile a record of ground motion intensity measures for California from 2002-present. We use this information to perform an area-based test of California PSHA maps inspired by the work of Ward (1995). Though this framework is flexible in that it can be applied to seismically active areas where ShakeMap-like ground shaking interpolations have or can be produced, this testing procedure is limited by the relatively short lifetime of strong motion recordings and by the desire to only test with data collected after the development of the PSHA map under scrutiny. To account for this, we use the assumption that PSHA maps are time independent to adapt the testing procedure for periods of recorded data shorter than the lifetime of a map. We note that accuracy of this testing procedure will only improve as more data is collected, or as the time-horizon of interest is reduced, as has been proposed for maps of areas experiencing induced seismicity. We believe that this procedure can be used to determine whether PSHA maps are accurately portraying seismic hazard and whether discrepancies are localized or systemic.

Documentation for the 2008 Update of the United States National Seismic Hazard Maps

USGS Publications Warehouse

Petersen, Mark D.; Frankel, Arthur D.; Harmsen, Stephen C.; Mueller, Charles S.; Haller, Kathleen M.; Wheeler, Russell L.; Wesson, Robert L.; Zeng, Yuehua; Boyd, Oliver S.; Perkins, David M.; Luco, Nicolas; Field, Edward H.; Wills, Chris J.; Rukstales, Kenneth S.

2008-01-01

The 2008 U.S. Geological Survey (USGS) National Seismic Hazard Maps display earthquake ground motions for various probability levels across the United States and are applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. This update of the maps incorporates new findings on earthquake ground shaking, faults, seismicity, and geodesy. The resulting maps are derived from seismic hazard curves calculated on a grid of sites across the United States that describe the frequency of exceeding a set of ground motions. The USGS National Seismic Hazard Mapping Project developed these maps by incorporating information on potential earthquakes and associated ground shaking obtained from interaction in science and engineering workshops involving hundreds of participants, review by several science organizations and State surveys, and advice from two expert panels. The National Seismic Hazard Maps represent our assessment of the 'best available science' in earthquake hazards estimation for the United States (maps of Alaska and Hawaii as well as further information on hazard across the United States are available on our Web site at http://earthquake.usgs.gov/research/hazmaps/).

Use of raster-based data layers to model spatial variation of seismotectonic data in probabilistic seismic hazard assessment

NASA Astrophysics Data System (ADS)

Zolfaghari, Mohammad R.

2009-07-01

Recent achievements in computer and information technology have provided the necessary tools to extend the application of probabilistic seismic hazard mapping from its traditional engineering use to many other applications. Examples for such applications are risk mitigation, disaster management, post disaster recovery planning and catastrophe loss estimation and risk management. Due to the lack of proper knowledge with regard to factors controlling seismic hazards, there are always uncertainties associated with all steps involved in developing and using seismic hazard models. While some of these uncertainties can be controlled by more accurate and reliable input data, the majority of the data and assumptions used in seismic hazard studies remain with high uncertainties that contribute to the uncertainty of the final results. In this paper a new methodology for the assessment of seismic hazard is described. The proposed approach provides practical facility for better capture of spatial variations of seismological and tectonic characteristics, which allows better treatment of their uncertainties. In the proposed approach, GIS raster-based data models are used in order to model geographical features in a cell-based system. The cell-based source model proposed in this paper provides a framework for implementing many geographically referenced seismotectonic factors into seismic hazard modelling. Examples for such components are seismic source boundaries, rupture geometry, seismic activity rate, focal depth and the choice of attenuation functions. The proposed methodology provides improvements in several aspects of the standard analytical tools currently being used for assessment and mapping of regional seismic hazard. The proposed methodology makes the best use of the recent advancements in computer technology in both software and hardware. The proposed approach is well structured to be implemented using conventional GIS tools.

Automatic recognition of seismic intensity based on RS and GIS: a case study in Wenchuan Ms8.0 earthquake of China.

PubMed

Zhang, Qiuwen; Zhang, Yan; Yang, Xiaohong; Su, Bin

2014-01-01

In recent years, earthquakes have frequently occurred all over the world, which caused huge casualties and economic losses. It is very necessary and urgent to obtain the seismic intensity map timely so as to master the distribution of the disaster and provide supports for quick earthquake relief. Compared with traditional methods of drawing seismic intensity map, which require many investigations in the field of earthquake area or are too dependent on the empirical formulas, spatial information technologies such as Remote Sensing (RS) and Geographical Information System (GIS) can provide fast and economical way to automatically recognize the seismic intensity. With the integrated application of RS and GIS, this paper proposes a RS/GIS-based approach for automatic recognition of seismic intensity, in which RS is used to retrieve and extract the information on damages caused by earthquake, and GIS is applied to manage and display the data of seismic intensity. The case study in Wenchuan Ms8.0 earthquake in China shows that the information on seismic intensity can be automatically extracted from remotely sensed images as quickly as possible after earthquake occurrence, and the Digital Intensity Model (DIM) can be used to visually query and display the distribution of seismic intensity.

Seismic hazard in the South Carolina coastal plain: 2002 update of the USGS national seismic hazard maps

USGS Publications Warehouse

Cramer, C.H.; Mays, T.W.; ,

2005-01-01

The damaging 1886 moment magnitude ???7 Charleston, South Carolina earthquake is indicative of the moderately likely earthquake activity along this portion of the Atlantic Coast. A recurrence of such an earthquake today would have serious consequences for the nation. The national seismic hazard maps produced by the U.S. Geological Survey (USGS) provide a picture of the levels of seismic hazard across the nation based on the best and most current scientific information. The USGS national maps were updated in 2002 and will become part of the International Codes in 2006. In the past decade, improvements have occurred in the scientific understanding of the nature and character of earthquake activity and expected ground motions in the central and eastern U.S. The paper summarizes the new knowledge of expected earthquake locations, magnitudes, recurrence, and ground-motion decay with distance. New estimates of peak ground acceleration and 0.2 s and 1.0 s spectral acceleration are compared with those displayed in the 1996 national maps. The 2002 maps show increased seismic hazard in much of the coastal plain of South Carolina, but a decrease in long period (1 s and greater) hazard by up to 20% at distances of over 50 km from the Charleston earthquake zone. Although the national maps do not account for the effects of local or regional sediments, deep coastal-plain sediments can significally alter expected ground shaking, particularly at long period motions where it can be 100% higher than the national maps.

Neo-Deterministic and Probabilistic Seismic Hazard Assessments: a Comparative Analysis

NASA Astrophysics Data System (ADS)

Peresan, Antonella; Magrin, Andrea; Nekrasova, Anastasia; Kossobokov, Vladimir; Panza, Giuliano F.

2016-04-01

Objective testing is the key issue towards any reliable seismic hazard assessment (SHA). Different earthquake hazard maps must demonstrate their capability in anticipating ground shaking from future strong earthquakes before an appropriate use for different purposes - such as engineering design, insurance, and emergency management. Quantitative assessment of maps performances is an essential step also in scientific process of their revision and possible improvement. Cross-checking of probabilistic models with available observations and independent physics based models is recognized as major validation procedure. The existing maps from the classical probabilistic seismic hazard analysis (PSHA), as well as those from the neo-deterministic analysis (NDSHA), which have been already developed for several regions worldwide (including Italy, India and North Africa), are considered to exemplify the possibilities of the cross-comparative analysis in spotting out limits and advantages of different methods. Where the data permit, a comparative analysis versus the documented seismic activity observed in reality is carried out, showing how available observations about past earthquakes can contribute to assess performances of the different methods. Neo-deterministic refers to a scenario-based approach, which allows for consideration of a wide range of possible earthquake sources as the starting point for scenarios constructed via full waveforms modeling. The method does not make use of empirical attenuation models (i.e. Ground Motion Prediction Equations, GMPE) and naturally supplies realistic time series of ground shaking (i.e. complete synthetic seismograms), readily applicable to complete engineering analysis and other mitigation actions. The standard NDSHA maps provide reliable envelope estimates of maximum seismic ground motion from a wide set of possible scenario earthquakes, including the largest deterministically or historically defined credible earthquake. In addition, the flexibility of NDSHA allows for generation of ground shaking maps at specified long-term return times, which may permit a straightforward comparison between NDSHA and PSHA maps in terms of average rates of exceedance for specified time windows. The comparison of NDSHA and PSHA maps, particularly for very long recurrence times, may indicate to what extent probabilistic ground shaking estimates are consistent with those from physical models of seismic waves propagation. A systematic comparison over the territory of Italy is carried out exploiting the uniqueness of the Italian earthquake catalogue, a data set covering more than a millennium (a time interval about ten times longer than that available in most of the regions worldwide) with a satisfactory completeness level for M>5, which warrants the results of analysis. By analysing in some detail seismicity in the Vrancea region, we show that well constrained macroseismic field information for individual earthquakes may provide useful information about the reliability of ground shaking estimates. Finally, in order to generalise observations, the comparative analysis is extended to further regions where both standard NDSHA and PSHA maps are available (e.g. State of Gujarat, India). The final Global Seismic Hazard Assessment Program (GSHAP) results and the most recent version of Seismic Hazard Harmonization in Europe (SHARE) project maps, along with other national scale probabilistic maps, all obtained by PSHA, are considered for this comparative analysis.

Seismic hazard maps of Mexico, the Caribbean, and Central and South America

USGS Publications Warehouse

Tanner, J.G.; Shedlock, K.M.

2004-01-01

The growth of megacities in seismically active regions around the world often includes the construction of seismically unsafe buildings and infrastructures due to an insufficient knowledge of existing seismic hazard and/or economic constraints. Minimization of the loss of life, property damage, and social and economic disruption due to earthquakes depends on reliable estimates of seismic hazard. We have produced a suite of seismic hazard estimates for Mexico, the Caribbean, and Central and South America. One of the preliminary maps in this suite served as the basis for the Caribbean and Central and South America portion of the Global Seismic Hazard Map (GSHM) published in 1999, which depicted peak ground acceleration (pga) with a 10% chance of exceedance in 50 years for rock sites. Herein we present maps depicting pga and 0.2 and 1.0 s spectral accelerations (SA) with 50%, 10%, and 2% chances of exceedance in 50 years for rock sites. The seismicity catalog used in the generation of these maps adds 3 more years of data to those used to calculate the GSH Map. Different attenuation functions (consistent with those used to calculate the U.S. and Canadian maps) were used as well. These nine maps are designed to assist in global risk mitigation by providing a general seismic hazard framework and serving as a resource for any national or regional agency to help focus further detailed studies required for regional/local needs. The largest seismic hazard values in Mexico, the Caribbean, and Central and South America generally occur in areas that have been, or are likely to be, the sites of the largest plate boundary earthquakes. High hazard values occur in areas where shallow-to-intermediate seismicity occurs frequently. ?? 2004 Elsevier B.V. All rights reserved.

Reducing the uncertainty in the fidelity of seismic imaging results

NASA Astrophysics Data System (ADS)

Zhou, H. W.; Zou, Z.

2017-12-01

A key aspect in geoscientific inversion is quantifying the quality of the results. In seismic imaging, we must quantify the uncertainty of every imaging result based on field data, because data noise and methodology limitations may produce artifacts. Detection of artifacts is therefore an important aspect in uncertainty quantification in geoscientific inversion. Quantifying the uncertainty of seismic imaging solutions means assessing their fidelity, which defines the truthfulness of the imaged targets in terms of their resolution, position error and artifact. Key challenges to achieving the fidelity of seismic imaging include: (1) Difficulty to tell signal from artifact and noise; (2) Limitations in signal-to-noise ratio and seismic illumination; and (3) The multi-scale nature of the data space and model space. Most seismic imaging studies of the Earth's crust and mantle have employed inversion or modeling approaches. Though they are in opposite directions of mapping between the data space and model space, both inversion and modeling seek the best model to minimize the misfit in the data space, which unfortunately is not the output space. The fact that the selection and uncertainty of the output model are not judged in the output space has exacerbated the nonuniqueness problem for inversion and modeling. In contrast, the practice in exploration seismology has long established a two-fold approach of seismic imaging: Using velocity modeling building to establish the long-wavelength reference velocity models, and using seismic migration to map the short-wavelength reflectivity structures. Most interestingly, seismic migration maps the data into an output space called imaging space, where the output reflection images of the subsurface are formed based on an imaging condition. A good example is the reverse time migration, which seeks the reflectivity image as the best fit in the image space between the extrapolation of time-reversed waveform data and the prediction based on estimated velocity model and source parameters. I will illustrate the benefits of deciding the best output result in the output space for inversion, using examples from seismic imaging.

Using geologic maps and seismic refraction in pavement-deflection analysis

DOT National Transportation Integrated Search

1999-10-01

The researchers examined the relationship between three data types -- geologic maps, pavement deflection, and seismic refraction data -- from diverse geologic settings to determine whether geologic maps and seismic data might be used to interpret def...

Fault specific GIS based seismic hazard maps for the Attica region, Greece

NASA Astrophysics Data System (ADS)

Deligiannakis, G.; Papanikolaou, I. D.; Roberts, G.

2018-04-01

Traditional seismic hazard assessment methods are based on the historical seismic records for the calculation of an annual probability of exceedance for a particular ground motion level. A new fault-specific seismic hazard assessment method is presented, in order to address problems related to the incompleteness and the inhomogeneity of the historical records and to obtain higher spatial resolution of hazard. This method is applied to the region of Attica, which is the most densely populated area in Greece, as nearly half of the country's population lives in Athens and its surrounding suburbs, in the Greater Athens area. The methodology is based on a database of 24 active faults that could cause damage to Attica in case of seismic rupture. This database provides information about the faults slip rates, lengths and expected magnitudes. The final output of the method is four fault-specific seismic hazard maps, showing the recurrence of expected intensities for each locality. These maps offer a high spatial resolution, as they consider the surface geology. Despite the fact that almost half of the Attica region lies on the lowest seismic risk zone according to the official seismic hazard zonation of Greece, different localities have repeatedly experienced strong ground motions during the last 15 kyrs. Moreover, the maximum recurrence for each intensity occurs in different localities across Attica. Highest recurrence for intensity VII (151-156 times over 15 kyrs, or up to a 96 year return period) is observed in the central part of the Athens basin. The maximum intensity VIII recurrence (115 times over 15 kyrs, or up to a 130 year return period) is observed in the western part of Attica, while the maximum intensity IX (73-77/15 kyrs, or a 195 year return period) and X (25-29/15 kyrs, or a 517 year return period) recurrences are observed near the South Alkyonides fault system, which dominates the strong ground motions hazard in the western part of the Attica mainland.

Incorporating induced seismicity in the 2014 United States National Seismic Hazard Model: results of the 2014 workshop and sensitivity studies

USGS Publications Warehouse

Petersen, Mark D.; Mueller, Charles S.; Moschetti, Morgan P.; Hoover, Susan M.; Rubinstein, Justin L.; Llenos, Andrea L.; Michael, Andrew J.; Ellsworth, William L.; McGarr, Arthur F.; Holland, Austin A.; Anderson, John G.

2015-01-01

The U.S. Geological Survey National Seismic Hazard Model for the conterminous United States was updated in 2014 to account for new methods, input models, and data necessary for assessing the seismic ground shaking hazard from natural (tectonic) earthquakes. The U.S. Geological Survey National Seismic Hazard Model project uses probabilistic seismic hazard analysis to quantify the rate of exceedance for earthquake ground shaking (ground motion). For the 2014 National Seismic Hazard Model assessment, the seismic hazard from potentially induced earthquakes was intentionally not considered because we had not determined how to properly treat these earthquakes for the seismic hazard analysis. The phrases “potentially induced” and “induced” are used interchangeably in this report, however it is acknowledged that this classification is based on circumstantial evidence and scientific judgment. For the 2014 National Seismic Hazard Model update, the potentially induced earthquakes were removed from the NSHM’s earthquake catalog, and the documentation states that we would consider alternative models for including induced seismicity in a future version of the National Seismic Hazard Model. As part of the process of incorporating induced seismicity into the seismic hazard model, we evaluate the sensitivity of the seismic hazard from induced seismicity to five parts of the hazard model: (1) the earthquake catalog, (2) earthquake rates, (3) earthquake locations, (4) earthquake Mmax (maximum magnitude), and (5) earthquake ground motions. We describe alternative input models for each of the five parts that represent differences in scientific opinions on induced seismicity characteristics. In this report, however, we do not weight these input models to come up with a preferred final model. Instead, we present a sensitivity study showing uniform seismic hazard maps obtained by applying the alternative input models for induced seismicity. The final model will be released after further consideration of the reliability and scientific acceptability of each alternative input model. Forecasting the seismic hazard from induced earthquakes is fundamentally different from forecasting the seismic hazard for natural, tectonic earthquakes. This is because the spatio-temporal patterns of induced earthquakes are reliant on economic forces and public policy decisions regarding extraction and injection of fluids. As such, the rates of induced earthquakes are inherently variable and nonstationary. Therefore, we only make maps based on an annual rate of exceedance rather than the 50-year rates calculated for previous U.S. Geological Survey hazard maps.

The new Central American seismic hazard zonation: Mutual consensus based on up to day seismotectonic framework

NASA Astrophysics Data System (ADS)

Alvarado, Guillermo E.; Benito, Belén; Staller, Alejandra; Climent, Álvaro; Camacho, Eduardo; Rojas, Wilfredo; Marroquín, Griselda; Molina, Enrique; Talavera, J. Emilio; Martínez-Cuevas, Sandra; Lindholm, Conrad

2017-11-01

Central America is one of the most active seismic zones in the World, due to the interaction of five tectonic plates (North America, Caribbean, Coco, Nazca and South America), and its internal deformation, which generates almost one destructive earthquakes (5.4 ≤ Mw ≤ 8.1) every year. A new seismological zonation for Central America is proposed based on seismotectonic framework, a geological context (tectonic and geological maps), geophysical and geodetic evidence (gravimetric maps, magnetometric, GPS observations), and previous works. As a main source of data a depurated earthquake catalog was collected covering the period from 1522 to 2015. This catalog was homogenized to a moment magnitude scale (Mw). After a careful analysis of all the integrated geological and seismological information, the seismogenic zones were established into seismic areas defined by similar patterns of faulting, seismicity, and rupture mechanism. The tectonic environment has required considering seismic zones in two particular seismological regimes: a) crustal faulting (including local faults, major fracture zones of plate boundary limits, and thrust fault of deformed belts) and b) subduction, taking into account the change in the subduction angle along the trench, and the type and location of the rupture. The seismicity in the subduction zone is divided into interplate and intraplate inslab seismicity. The regional seismic zonation proposed for the whole of Central America, include local seismic zonations, avoiding discontinuities at the national boundaries, because of a consensus between the 7 countries, based on the cooperative work of specialists on Central American seismotectonics and related topics.

Seismic design parameters - A user guide

USGS Publications Warehouse

Leyendecker, E.V.; Frankel, A.D.; Rukstales, K.S.

2001-01-01

The 1997 NEHRP Recommended Provisions for Seismic Regulations for New Buildings (1997 NEHRP Provisions) introduced seismic design procedure that is based on the explicit use of spectral response acceleration rather than the traditional peak ground acceleration and/or peak ground velocity or zone factors. The spectral response accelerations are obtained from spectral response acceleration maps accompanying the report. Maps are available for the United States and a number of U.S. territories. Since 1997 additional codes and standards have also adopted seismic design approaches based on the same procedure used in the NEHRP Provisions and the accompanying maps. The design documents using the 1997 NEHRP Provisions procedure may be divided into three categories -(1) Design of New Construction, (2) Design and Evaluation of Existing Construction, and (3) Design of Residential Construction. A CD-ROM has been prepared for use in conjunction with the design documents in each of these three categories. The spectral accelerations obtained using the software on the CD are the same as those that would be obtained by using the maps accompanying the design documents. The software has been prepared to operate on a personal computer using a Windows (Microsoft Corporation) operating environment and a point and click type of interface. The user can obtain the spectral acceleration values that would be obtained by use of the maps accompanying the design documents, include site factors appropriate for the Site Class provided by the user, calculate a response spectrum that includes the site factor, and plot a response spectrum. Sites may be located by providing the latitude-longitude or zip code for all areas covered by the maps. All of the maps used in the various documents are also included on the CDROM

Assessment of macroseismic intensity in the Nile basin, Egypt

NASA Astrophysics Data System (ADS)

Fergany, Elsayed

2018-01-01

This work intends to assess deterministic seismic hazard and risk analysis in terms of the maximum expected intensity map of the Egyptian Nile basin sector. Seismic source zone model of Egypt was delineated based on updated compatible earthquake catalog in 2015, focal mechanisms, and the common tectonic elements. Four effective seismic source zones were identified along the Nile basin. The observed macroseismic intensity data along the basin was used to develop intensity prediction equation defined in terms of moment magnitude. Expected maximum intensity map was proven based on the developed intensity prediction equation, identified effective seismic source zones, and maximum expected magnitude for each zone along the basin. The earthquake hazard and risk analysis was discussed and analyzed in view of the maximum expected moment magnitude and the maximum expected intensity values for each effective source zone. Moderate expected magnitudes are expected to put high risk at Cairo and Aswan regions. The results of this study could be a recommendation for the planners in charge to mitigate the seismic risk at these strategic zones of Egypt.

SiSeRHMap v1.0: a simulator for mapped seismic response using a hybrid model

NASA Astrophysics Data System (ADS)

Grelle, G.; Bonito, L.; Lampasi, A.; Revellino, P.; Guerriero, L.; Sappa, G.; Guadagno, F. M.

2015-06-01

SiSeRHMap is a computerized methodology capable of drawing up prediction maps of seismic response. It was realized on the basis of a hybrid model which combines different approaches and models in a new and non-conventional way. These approaches and models are organized in a code-architecture composed of five interdependent modules. A GIS (Geographic Information System) Cubic Model (GCM), which is a layered computational structure based on the concept of lithodynamic units and zones, aims at reproducing a parameterized layered subsoil model. A metamodeling process confers a hybrid nature to the methodology. In this process, the one-dimensional linear equivalent analysis produces acceleration response spectra of shear wave velocity-thickness profiles, defined as trainers, which are randomly selected in each zone. Subsequently, a numerical adaptive simulation model (Spectra) is optimized on the above trainer acceleration response spectra by means of a dedicated Evolutionary Algorithm (EA) and the Levenberg-Marquardt Algorithm (LMA) as the final optimizer. In the final step, the GCM Maps Executor module produces a serial map-set of a stratigraphic seismic response at different periods, grid-solving the calibrated Spectra model. In addition, the spectra topographic amplification is also computed by means of a numerical prediction model. This latter is built to match the results of the numerical simulations related to isolate reliefs using GIS topographic attributes. In this way, different sets of seismic response maps are developed, on which, also maps of seismic design response spectra are defined by means of an enveloping technique.

SiSeRHMap v1.0: a simulator for mapped seismic response using a hybrid model

NASA Astrophysics Data System (ADS)

Grelle, Gerardo; Bonito, Laura; Lampasi, Alessandro; Revellino, Paola; Guerriero, Luigi; Sappa, Giuseppe; Guadagno, Francesco Maria

2016-04-01

The SiSeRHMap (simulator for mapped seismic response using a hybrid model) is a computerized methodology capable of elaborating prediction maps of seismic response in terms of acceleration spectra. It was realized on the basis of a hybrid model which combines different approaches and models in a new and non-conventional way. These approaches and models are organized in a code architecture composed of five interdependent modules. A GIS (geographic information system) cubic model (GCM), which is a layered computational structure based on the concept of lithodynamic units and zones, aims at reproducing a parameterized layered subsoil model. A meta-modelling process confers a hybrid nature to the methodology. In this process, the one-dimensional (1-D) linear equivalent analysis produces acceleration response spectra for a specified number of site profiles using one or more input motions. The shear wave velocity-thickness profiles, defined as trainers, are randomly selected in each zone. Subsequently, a numerical adaptive simulation model (Emul-spectra) is optimized on the above trainer acceleration response spectra by means of a dedicated evolutionary algorithm (EA) and the Levenberg-Marquardt algorithm (LMA) as the final optimizer. In the final step, the GCM maps executor module produces a serial map set of a stratigraphic seismic response at different periods, grid solving the calibrated Emul-spectra model. In addition, the spectra topographic amplification is also computed by means of a 3-D validated numerical prediction model. This model is built to match the results of the numerical simulations related to isolate reliefs using GIS morphometric data. In this way, different sets of seismic response maps are developed on which maps of design acceleration response spectra are also defined by means of an enveloping technique.

Characterising large scenario earthquakes and their influence on NDSHA maps

NASA Astrophysics Data System (ADS)

Magrin, Andrea; Peresan, Antonella; Panza, Giuliano F.

2016-04-01

The neo-deterministic approach to seismic zoning, NDSHA, relies on physically sound modelling of ground shaking from a large set of credible scenario earthquakes, which can be defined based on seismic history and seismotectonics, as well as incorporating information from a wide set of geological and geophysical data (e.g. morphostructural features and present day deformation processes identified by Earth observations). NDSHA is based on the calculation of complete synthetic seismograms; hence it does not make use of empirical attenuation models (i.e. ground motion prediction equations). From the set of synthetic seismograms, maps of seismic hazard that describe the maximum of different ground shaking parameters at the bedrock can be produced. As a rule, the NDSHA, defines the hazard as the envelope ground shaking at the site, computed from all of the defined seismic sources; accordingly, the simplest outcome of this method is a map where the maximum of a given seismic parameter is associated to each site. In this way, the standard NDSHA maps permit to account for the largest observed or credible earthquake sources identified in the region in a quite straightforward manner. This study aims to assess the influence of unavoidable uncertainties in the characterisation of large scenario earthquakes on the NDSHA estimates. The treatment of uncertainties is performed by sensitivity analyses for key modelling parameters and accounts for the uncertainty in the prediction of fault radiation and in the use of Green's function for a given medium. Results from sensitivity analyses with respect to the definition of possible seismic sources are discussed. A key parameter is the magnitude of seismic sources used in the simulation, which is based on information from earthquake catalogue, seismogenic zones and seismogenic nodes. The largest part of the existing Italian catalogues is based on macroseismic intensities, a rough estimate of the error in peak values of ground motion can therefore be the factor of two, intrinsic in MCS and other discrete scales. A simple test supports this hypothesis: an increase of 0.5 in the magnitude, i.e. one degrees in epicentral MCS, of all sources used in the national scale seismic zoning produces a doubling of the maximum ground motion. The analysis of uncertainty in ground motion maps, due to the catalogue random errors in magnitude and localization, shows a not uniform distribution of ground shaking uncertainty. The available information from catalogues of past events, that is not complete and may well not be representative of future earthquakes, can be substantially completed using independent indicators of the seismogenic potential of a given area, such as active faulting data and the seismogenic nodes.

A seismic hazard uncertainty analysis for the New Madrid seismic zone

USGS Publications Warehouse

Cramer, C.H.

2001-01-01

A review of the scientific issues relevant to characterizing earthquake sources in the New Madrid seismic zone has led to the development of a logic tree of possible alternative parameters. A variability analysis, using Monte Carlo sampling of this consensus logic tree, is presented and discussed. The analysis shows that for 2%-exceedence-in-50-year hazard, the best-estimate seismic hazard map is similar to previously published seismic hazard maps for the area. For peak ground acceleration (PGA) and spectral acceleration at 0.2 and 1.0 s (0.2 and 1.0 s Sa), the coefficient of variation (COV) representing the knowledge-based uncertainty in seismic hazard can exceed 0.6 over the New Madrid seismic zone and diminishes to about 0.1 away from areas of seismic activity. Sensitivity analyses show that the largest contributor to PGA, 0.2 and 1.0 s Sa seismic hazard variability is the uncertainty in the location of future 1811-1812 New Madrid sized earthquakes. This is followed by the variability due to the choice of ground motion attenuation relation, the magnitude for the 1811-1812 New Madrid earthquakes, and the recurrence interval for M>6.5 events. Seismic hazard is not very sensitive to the variability in seismogenic width and length. Published by Elsevier Science B.V.

Integrating population dynamics into mapping human exposure to seismic hazard

NASA Astrophysics Data System (ADS)

Freire, S.; Aubrecht, C.

2012-11-01

Disaster risk is not fully characterized without taking into account vulnerability and population exposure. Assessment of earthquake risk in urban areas would benefit from considering the variation of population distribution at more detailed spatial and temporal scales, and from a more explicit integration of this improved demographic data with existing seismic hazard maps. In the present work, "intelligent" dasymetric mapping is used to model population dynamics at high spatial resolution in order to benefit the analysis of spatio-temporal exposure to earthquake hazard in a metropolitan area. These night- and daytime-specific population densities are then classified and combined with seismic intensity levels to derive new spatially-explicit four-class-composite maps of human exposure. The presented approach enables a more thorough assessment of population exposure to earthquake hazard. Results show that there are significantly more people potentially at risk in the daytime period, demonstrating the shifting nature of population exposure in the daily cycle and the need to move beyond conventional residence-based demographic data sources to improve risk analyses. The proposed fine-scale maps of human exposure to seismic intensity are mainly aimed at benefiting visualization and communication of earthquake risk, but can be valuable in all phases of the disaster management process where knowledge of population densities is relevant for decision-making.

Implementation of NGA-West2 ground motion models in the 2014 U.S. National Seismic Hazard Maps

USGS Publications Warehouse

Rezaeian, Sanaz; Petersen, Mark D.; Moschetti, Morgan P.; Powers, Peter; Harmsen, Stephen C.; Frankel, Arthur D.

2014-01-01

The U.S. National Seismic Hazard Maps (NSHMs) have been an important component of seismic design regulations in the United States for the past several decades. These maps present earthquake ground shaking intensities at specified probabilities of being exceeded over a 50-year time period. The previous version of the NSHMs was developed in 2008; during 2012 and 2013, scientists at the U.S. Geological Survey have been updating the maps based on their assessment of the “best available science,” resulting in the 2014 NSHMs. The update includes modifications to the seismic source models and the ground motion models (GMMs) for sites across the conterminous United States. This paper focuses on updates in the Western United States (WUS) due to the use of new GMMs for shallow crustal earthquakes in active tectonic regions developed by the Next Generation Attenuation (NGA-West2) project. Individual GMMs, their weighted combination, and their impact on the hazard maps relative to 2008 are discussed. In general, the combined effects of lower medians and increased standard deviations in the new GMMs have caused only small changes, within 5–20%, in the probabilistic ground motions for most sites across the WUS compared to the 2008 NSHMs.

Seismic zonation of Port-Au-Prince using pixel- and object-based imaging analysis methods on ASTER GDEM

USGS Publications Warehouse

Yong, Alan; Hough, Susan E.; Cox, Brady R.; Rathje, Ellen M.; Bachhuber, Jeff; Dulberg, Ranon; Hulslander, David; Christiansen, Lisa; and Abrams, Michael J.

2011-01-01

We report about a preliminary study to evaluate the use of semi-automated imaging analysis of remotely-sensed DEM and field geophysical measurements to develop a seismic-zonation map of Port-au-Prince, Haiti. For in situ data, VS30 values are derived from the MASW technique deployed in and around the city. For satellite imagery, we use an ASTER GDEM of Hispaniola. We apply both pixel- and object-based imaging methods on the ASTER GDEM to explore local topography (absolute elevation values) and classify terrain types such as mountains, alluvial fans and basins/near-shore regions. We assign NEHRP seismic site class ranges based on available VS30 values. A comparison of results from imagery-based methods to results from traditional geologic-based approaches reveals good overall correspondence. We conclude that image analysis of RS data provides reliable first-order site characterization results in the absence of local data and can be useful to refine detailed site maps with sparse local data.

Urban Seismic Hazard Mapping for Memphis, Shelby County, Tennessee

USGS Publications Warehouse

Gomberg, Joan

2006-01-01

Earthquakes cannot be predicted, but scientists can forecast how strongly the ground is likely to shake as a result of an earthquake. Seismic hazard maps provide one way of conveying such forecasts. The U.S. Geological Survey (USGS), which produces seismic hazard maps for the Nation, is now engaged in developing more detailed maps for vulnerable urban areas. The first set of these maps is now available for Memphis, Tennessee.

Receiver deghosting in the t-x domain based on super-Gaussianity

NASA Astrophysics Data System (ADS)

Lu, Wenkai; Xu, Ziqiang; Fang, Zhongyu; Wang, Ruiliang; Yan, Chengzhi

2017-01-01

Deghosting methods in the time-space (t-x) domain have attracted a lot of attention because of their flexibility for various source/receiver configurations. Based on the well-known knowledge that the seismic signal has a super-Gaussian distribution, we present a Super-Gaussianity based Receiver Deghosting (SRD) method in the t-x domain. In our method, we denote the upgoing wave and its ghost (downgoing wave) as a single seismic signal, and express the relationship between the upgoing wave and its ghost using two ghost parameters: the sea surface reflection coefficient and the time-shift between the upgoing wave and its ghost. For a single seismic signal, we estimate these two parameters by maximizing the super-Gaussianity of the deghosted output, which is achieved by a 2D grid search method using an adaptively predefined discrete solution space. Since usually a large number of seismic signals are mixed together in a seismic trace, in the proposed method we divide the seismic trace into overlapping frames using a sliding time window with a step of one time sample, and consider each frame as a replacement for a single seismic signal. For a 2D seismic gather, we obtain two 2D maps of the ghost parameters. By assuming that these two parameters vary slowly in the t-x domain, we apply a 2D average filter to these maps, to improve their reliability further. Finally, these deghosted outputs are merged to form the final deghosted result. To demonstrate the flexibility of the proposed method for arbitrary variable depths of the receivers, we apply it to several synthetic and field seismic datasets acquired by variable depth streamer.

Seismic hazard assessment of the cultural heritage sites: A case study in Cappadocia (Turkey)

NASA Astrophysics Data System (ADS)

Seyrek, Evren; Orhan, Ahmet; Dinçer, İsmail

2014-05-01

Turkey is one of the most seismically active regions in the world. Major earthquakes with the potential of threatening life and property occur frequently here. In the last decade, over 50,000 residents lost their lives, commonly as a result of building failures in seismic events. The Cappadocia region is one of the most important touristic sites in Turkey. At the same time, the region has been included to the Word Heritage List by UNESCO at 1985 due to its natural, historical and cultural values. The region is undesirably affected by several environmental conditions, which are subjected in many previous studies. But, there are limited studies about the seismic evaluation of the region. Some of the important historical and cultural heritage sites are: Goreme Open Air Museum, Uchisar Castle, Ortahisar Castle, Derinkuyu Underground City and Ihlara Valley. According to seismic hazard zonation map published by the Ministry of Reconstruction and Settlement these heritage sites fall in Zone III, Zone IV and Zone V. This map show peak ground acceleration or 10 percent probability of exceedance in 50 years for bedrock. In this connection, seismic hazard assessment of these heritage sites has to be evaluated. In this study, seismic hazard calculations are performed both deterministic and probabilistic approaches with local site conditions. A catalog of historical and instrumental earthquakes is prepared and used in this study. The seismic sources have been identified for seismic hazard assessment based on geological, seismological and geophysical information. Peak Ground Acceleration (PGA) at bed rock level is calculated for different seismic sources using available attenuation relationship formula applicable to Turkey. The result of the present study reveals that the seismic hazard at these sites is closely matching with the Seismic Zonation map published by the Ministry of Reconstruction and Settlement. Keywords: Seismic Hazard Assessment, Probabilistic Approach, Deterministic Approach, Historical Heritage, Cappadocia.

Neo-deterministic seismic hazard scenarios for India—a preventive tool for disaster mitigation

NASA Astrophysics Data System (ADS)

Parvez, Imtiyaz A.; Magrin, Andrea; Vaccari, Franco; Ashish; Mir, Ramees R.; Peresan, Antonella; Panza, Giuliano Francesco

2017-11-01

Current computational resources and physical knowledge of the seismic wave generation and propagation processes allow for reliable numerical and analytical models of waveform generation and propagation. From the simulation of ground motion, it is easy to extract the desired earthquake hazard parameters. Accordingly, a scenario-based approach to seismic hazard assessment has been developed, namely the neo-deterministic seismic hazard assessment (NDSHA), which allows for a wide range of possible seismic sources to be used in the definition of reliable scenarios by means of realistic waveforms modelling. Such reliable and comprehensive characterization of expected earthquake ground motion is essential to improve building codes, particularly for the protection of critical infrastructures and for land use planning. Parvez et al. (Geophys J Int 155:489-508, 2003) published the first ever neo-deterministic seismic hazard map of India by computing synthetic seismograms with input data set consisting of structural models, seismogenic zones, focal mechanisms and earthquake catalogues. As described in Panza et al. (Adv Geophys 53:93-165, 2012), the NDSHA methodology evolved with respect to the original formulation used by Parvez et al. (Geophys J Int 155:489-508, 2003): the computer codes were improved to better fit the need of producing realistic ground shaking maps and ground shaking scenarios, at different scale levels, exploiting the most significant pertinent progresses in data acquisition and modelling. Accordingly, the present study supplies a revised NDSHA map for India. The seismic hazard, expressed in terms of maximum displacement (Dmax), maximum velocity (Vmax) and design ground acceleration (DGA), has been extracted from the synthetic signals and mapped on a regular grid over the studied territory.

Successful gas hydrate prospecting using 3D seismic - A case study for the Mt. Elbert prospect, Milne Point, North Slope Alaska

USGS Publications Warehouse

Inks, T.L.; Agena, W.F.

2008-01-01

In February 2007, the Mt. Elbert Prospect stratigraphic test well, Milne Point, North Slope Alaska encountered thick methane gas hydrate intervals, as predicted by 3D seismic interpretation and modeling. Methane gas hydrate-saturated sediment was found in two intervals, totaling more than 100 ft., identified and mapped based on seismic character and wavelet modeling.

Near-real-time information products for Mount St. Helens -- tracking the ongoing eruption: Chapter 3 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

USGS Publications Warehouse

Qamar, Anthony I.; Malone, Stephen; Moran, Seth C.; Steele, William P.; Thelen, Weston A.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

2008-01-01

The rapid onset of energetic seismicity on September 23, 2004, at Mount St. Helens caused seismologists at the Pacific Northwest Seismic Network and the Cascades Volcano Observatory to quickly improve and develop techniques that summarized and displayed seismic parameters for use by scientists and the general public. Such techniques included webicorders (Web-based helicorder-like displays), graphs showing RSAM (real-time seismic amplitude measurements), RMS (root-mean-square) plots, spectrograms, location maps, automated seismic-event detectors, focal mechanism solutions, automated approximations of earthquake magnitudes, RSAM-based alarms, and time-depth plots for seismic events. Many of these visual-information products were made available publicly as Web pages generated and updated routinely. The graphs and maps included short written text that explained the concepts behind them, which increased their value to the nonseismologic community that was tracking the eruption. Laypeople could read online summaries of the scientific interpretations and, if they chose, review some of the basic data, thereby providing a better understanding of the data used by scientists to make interpretations about ongoing eruptive activity, as well as a better understanding of how scientists worked to monitor the volcano.

Effect of Fault Parameter Uncertainties on PSHA explored by Monte Carlo Simulations: A case study for southern Apennines, Italy

NASA Astrophysics Data System (ADS)

Akinci, A.; Pace, B.

2017-12-01

In this study, we discuss the seismic hazard variability of peak ground acceleration (PGA) at 475 years return period in the Southern Apennines of Italy. The uncertainty and parametric sensitivity are presented to quantify the impact of the several fault parameters on ground motion predictions for 10% exceedance in 50-year hazard. A time-independent PSHA model is constructed based on the long-term recurrence behavior of seismogenic faults adopting the characteristic earthquake model for those sources capable of rupturing the entire fault segment with a single maximum magnitude. The fault-based source model uses the dimensions and slip rates of mapped fault to develop magnitude-frequency estimates for characteristic earthquakes. Variability of the selected fault parameter is given with a truncated normal random variable distribution presented by standard deviation about a mean value. A Monte Carlo approach, based on the random balanced sampling by logic tree, is used in order to capture the uncertainty in seismic hazard calculations. For generating both uncertainty and sensitivity maps, we perform 200 simulations for each of the fault parameters. The results are synthesized both in frequency-magnitude distribution of modeled faults as well as the different maps: the overall uncertainty maps provide a confidence interval for the PGA values and the parameter uncertainty maps determine the sensitivity of hazard assessment to variability of every logic tree branch. These branches of logic tree, analyzed through the Monte Carlo approach, are maximum magnitudes, fault length, fault width, fault dip and slip rates. The overall variability of these parameters is determined by varying them simultaneously in the hazard calculations while the sensitivity of each parameter to overall variability is determined varying each of the fault parameters while fixing others. However, in this study we do not investigate the sensitivity of mean hazard results to the consideration of different GMPEs. Distribution of possible seismic hazard results is illustrated by 95% confidence factor map, which indicates the dispersion about mean value, and coefficient of variation map, which shows percent variability. The results of our study clearly illustrate the influence of active fault parameters to probabilistic seismic hazard maps.

Seismic hazard map of North and Central America and the Caribbean

USGS Publications Warehouse

Shedlock, K.M.

1999-01-01

Minimization of the loss of life, property damage, and social and economic disruption due to earthquakes depends on reliable estimates of seismic hazard. National, state, and local government, decision makers, engineers, planners, emergency response organizations, builders, universities, and the general public require seismic hazard estimates for land use planning, improved building design and construction (including adoption of building construction codes), emergency response preparedness plans, economic forecasts, housing and employment decisions, and many more types of risk mitigation. The seismic hazard map of North and Central America and the Caribbean is the concatenation of various national and regional maps, involving a suite of approaches. The combined maps and documentation provide a useful regional seismic hazard framework and serve as a resource for any national or regional agency for further detailed studies applicable to their needs. This seismic hazard map depicts Peak Ground Acceleration (PGA) with a 10% chance of exceedance in 50 years. PGA, a short-period ground motion parameter that is proportional to force, is the most commonly mapped ground motion parameter because current building codes that include seismic provisions specify the horizontal force a building should be able to withstand during an earthquake. This seismic hazard map of North and Central America and the Caribbean depicts the likely level of short-period ground motion from earthquakes in a fifty-year window. Short-period ground motions effect short-period structures (e.g., one-to-two story buildings). The highest seismic hazard values in the region generally occur in areas that have been, or are likely to be, the sites of the largest plate boundary earthquakes.

Seismic Hazard Assessment at Esfaraen‒Bojnurd Railway, North‒East of Iran

NASA Astrophysics Data System (ADS)

Haerifard, S.; Jarahi, H.; Pourkermani, M.; Almasian, M.

2018-01-01

The objective of this study is to evaluate the seismic hazard at the Esfarayen-Bojnurd railway using the probabilistic seismic hazard assessment (PSHA) method. This method was carried out based on a recent data set to take into account the historic seismicity and updated instrumental seismicity. A homogenous earthquake catalogue was compiled and a proposed seismic sources model was presented. Attenuation equations that recently recommended by experts and developed based upon earthquake data obtained from tectonic environments similar to those in and around the studied area were weighted and used for assessment of seismic hazard in the frame of logic tree approach. Considering a grid of 1.2 × 1.2 km covering the study area, ground acceleration for every node was calculated. Hazard maps at bedrock conditions were produced for peak ground acceleration, in addition to return periods of 74, 475 and 2475 years.

The U.S. Geological Survey's Earthquake Summary Posters: A GIS-based Education and Communication Product for Presenting Consolidated Post-Earthquake Information

NASA Astrophysics Data System (ADS)

Tarr, A.; Benz, H.; Earle, P.; Wald, D. J.

2003-12-01

Earthquake Summary Posters (ESP's), a new product of the U.S. Geological Survey's Earthquake Program, are produced at the National Earthquake Information Center (NEIC) in Golden. The posters consist of rapidly-generated, GIS-based maps made following significant earthquakes worldwide (typically M>7.0, or events of significant media/public interest). ESP's consolidate, in an attractive map format, a large-scale epicentral map, several auxiliary regional overviews (showing tectonic and geographical setting, seismic history, seismic hazard, and earthquake effects), depth sections (as appropriate), a table of regional earthquakes, and a summary of the reional seismic history and tectonics. The immediate availability of the latter text summaries has been facilitated by the availability of Rapid, Accurate Tectonic Summaries (RATS) produced at NEIC and posted on the web following significant events. The rapid production of ESP's has been facilitated by generating, during the past two years, regional templates for tectonic areas around the world by organizing the necessary spatially-referenced data for the map base and the thematic layers that overlay the base. These GIS databases enable scripted Arc Macro Language (AML) production of routine elements of the maps (for example background seismicity, tectonic features, and probabilistic hazard maps). However, other elements of the maps are earthquake-specific and are produced manually to reflect new data, earthquake effects, and special characteristics. By the end of this year, approximately 85% of the Earth's seismic zones will be covered for generating future ESP's. During the past year, 13 posters were completed, comparable to the yearly average expected for significant earthquakes. Each year, all ESPs will be published on a CD in PDF format as an Open-File Report. In addition, each is linked to the special event earthquake pages on the USGS Earthquake Program web site (http://earthquake.usgs.gov). Although three formats are generated, the poster-size format is the most popular for display, outreach, and use as a working map for project scientists (JPEG format for web; PDF for download, editing, and printing) whereas the other (smaller) formats are suitable for briefing packages. We will soon make both GIS and PDF files of individual elements of the posters available online. ESP's provide an unprecedented opportunity for college earth-science faculty to take advantage of current events for timely lessons in global tectonics. They are also invaluable to communicate with the media and with government officials. ESP's will be used as a vehicle to present other products now under development under the auspices of NEIC and the ANSS, including rapid finite-fault models, global predictive ShakeMaps, "Did You Feel It?", and Rapid Assessments of Global Earthquakes (RAGE, Earle and others, this meeting).

Numerical investigations on mapping permeability heterogeneity in coal seam gas reservoirs using seismo-electric methods

NASA Astrophysics Data System (ADS)

Gross, L.; Shaw, S.

2016-04-01

Mapping the horizontal distribution of permeability is a key problem for the coal seam gas industry. Poststack seismic data with anisotropy attributes provide estimates for fracture density and orientation which are then interpreted in terms of permeability. This approach delivers an indirect measure of permeability and can fail if other sources of anisotropy (for instance stress) come into play. Seismo-electric methods, based on recording the electric signal from pore fluid movements stimulated through a seismic wave, measure permeability directly. In this paper we use numerical simulations to demonstrate that the seismo-electric method is potentially suitable to map the horizontal distribution of permeability changes across coal seams. We propose the use of an amplitude to offset (AVO) analysis of the electrical signal in combination with poststack seismic data collected during the exploration phase. Recording of electrical signals from a simple seismic source can be closer to production planning and operations. The numerical model is based on a sonic wave propagation model under the low frequency, saturated media assumption and uses a coupled high order spectral element and low order finite element solver. We investigate the impact of seam thickness, coal seam layering, layering in the overburden and horizontal heterogeneity of permeability.

Structural and Sequence Stratigraphic Analysis of the Onshore Nile Delta, Egypt.

NASA Astrophysics Data System (ADS)

Barakat, Moataz; Dominik, Wilhelm

2010-05-01

The Nile Delta is considered the earliest known delta in the world. It was already described by Herodotus in the 5th Century AC. Nowadays; the Nile Delta is an emerging giant gas province in the Middle East with proven gas reserves which have more than doubled in size in the last years. The Nile Delta basin contains a thick sedimentary sequence inferred to extend from Jurassic to recent time. Structural styles and depositional environments varied during this period. Facies architecture and sequence stratigraphy of the Nile Delta are resolved using seismic stratigraphy based on (2D seismic lines) including synthetic seismograms and tying in well log data. Synthetic seismograms were constructed using sonic and density logs. The combination of structural interpretation and sequence stratigraphy of the development of the basin was resolved. Seven chrono-stratigraphic boundaries have been identified and correlated on seismic and well log data. Several unconformity boundaries also identified on seismic lines range from angular to disconformity type. Furthermore, time structure maps, velocity maps, depth structure maps as well as Isopach maps were constructed using seismic lines and log data. Several structural features were identified: normal faults, growth faults, listric faults, secondary antithetic faults and large rotated fault blocks of manly Miocene age. In some cases minor rollover structures could be identified. Sedimentary features such as paleo-channels were distinctively recognized. Typical Sequence stratigraphic features such as incised valley, clinoforms, topsets, offlaps and onlaps are identified and traced on the seismic lines allowing a good insight into sequence stratigraphic history of the Nile Delta most especially in the Miocene to Pliocene clastic sedimentary succession.

How a Country-Wide Seismological Network Can Improve Understanding of Seismicity and Seismic Hazard -- The Example of Bhutan

NASA Astrophysics Data System (ADS)

Hetényi, G.; Diehl, T.; Singer, J.; Kissling, E. H.; Clinton, J. F.; Wiemer, S.

2015-12-01

The Eastern Himalayas are home to a seemingly complex seismo-tectonic evolution. The rate of instrumental seismicity is lower than the average along the orogen, there is no record of large historical events, but both paleoseismology and GPS studies point to potentially large (M>8) earthquakes. Due to the lack of a permanent seismic monitoring system in the area, our current level of understanding is inappropriate to create a reliable quantitative seismic hazard model for the region. Existing maps are based on questionable hypotheses and show major inconsistencies when compared to each other. Here we present results on national and regional scales from a 38-station broadband seismological network we operated for almost 2 years in the Kingdom of Bhutan. A thorough, state-of-the-art analysis of local and regional earthquakes builds a comprehensive catalogue that reveals significantly (2-to-3 orders of magnitude) more events than detected from global networks. The seismotectonic analysis reveals new patterns of seismic activity as well as striking differences over relatively short distances within the Himalayas, only partly explained by surface observations such as geology. We compare a priori and a posteriori (BMC) magnitude of completeness maps and show that our network was able to detect all felt events during its operation. Some of these events could be felt at surprisingly large distances. Based on our experiment and experience, we draft the pillars on which a permanent seismological observatory for Bhutan could be constructed. Such a continuous monitoring system of seismic activity could then lead to a reliable quantitative seismic hazard model for Bhutan and surrounding regions, and serve as a base to improve building codes and general preparedness.

Seismic hazards in Thailand: a compilation and updated probabilistic analysis

NASA Astrophysics Data System (ADS)

Pailoplee, Santi; Charusiri, Punya

2016-06-01

A probabilistic seismic hazard analysis (PSHA) for Thailand was performed and compared to those of previous works. This PSHA was based upon (1) the most up-to-date paleoseismological data (slip rates), (2) the seismic source zones, (3) the seismicity parameters ( a and b values), and (4) the strong ground-motion attenuation models suggested as being suitable models for Thailand. For the PSHA mapping, both the ground shaking and probability of exceedance (POE) were analyzed and mapped using various methods of presentation. In addition, site-specific PSHAs were demonstrated for ten major provinces within Thailand. For instance, a 2 and 10 % POE in the next 50 years of a 0.1-0.4 g and 0.1-0.2 g ground shaking, respectively, was found for western Thailand, defining this area as the most earthquake-prone region evaluated in Thailand. In a comparison between the ten selected specific provinces within Thailand, the Kanchanaburi and Tak provinces had comparatively high seismic hazards, and therefore, effective mitigation plans for these areas should be made. Although Bangkok was defined as being within a low seismic hazard in this PSHA, a further study of seismic wave amplification due to the soft soil beneath Bangkok is required.

A method for producing digital probabilistic seismic landslide hazard maps

USGS Publications Warehouse

Jibson, R.W.; Harp, E.L.; Michael, J.A.

2000-01-01

The 1994 Northridge, California, earthquake is the first earthquake for which we have all of the data sets needed to conduct a rigorous regional analysis of seismic slope instability. These data sets include: (1) a comprehensive inventory of triggered landslides, (2) about 200 strong-motion records of the mainshock, (3) 1:24 000-scale geologic mapping of the region, (4) extensive data on engineering properties of geologic units, and (5) high-resolution digital elevation models of the topography. All of these data sets have been digitized and rasterized at 10 m grid spacing using ARC/INFO GIS software on a UNIX computer. Combining these data sets in a dynamic model based on Newmark's permanent-deformation (sliding-block) analysis yields estimates of coseismic landslide displacement in each grid cell from the Northridge earthquake. The modeled displacements are then compared with the digital inventory of landslides triggered by the Northridge earthquake to construct a probability curve relating predicted displacement to probability of failure. This probability function can be applied to predict and map the spatial variability in failure probability in any ground-shaking conditions of interest. We anticipate that this mapping procedure will be used to construct seismic landslide hazard maps that will assist in emergency preparedness planning and in making rational decisions regarding development and construction in areas susceptible to seismic slope failure. ?? 2000 Elsevier Science B.V. All rights reserved.

A method for producing digital probabilistic seismic landslide hazard maps; an example from the Los Angeles, California, area

USGS Publications Warehouse

Jibson, Randall W.; Harp, Edwin L.; Michael, John A.

1998-01-01

The 1994 Northridge, California, earthquake is the first earthquake for which we have all of the data sets needed to conduct a rigorous regional analysis of seismic slope instability. These data sets include (1) a comprehensive inventory of triggered landslides, (2) about 200 strong-motion records of the mainshock, (3) 1:24,000-scale geologic mapping of the region, (4) extensive data on engineering properties of geologic units, and (5) high-resolution digital elevation models of the topography. All of these data sets have been digitized and rasterized at 10-m grid spacing in the ARC/INFO GIS platform. Combining these data sets in a dynamic model based on Newmark's permanent-deformation (sliding-block) analysis yields estimates of coseismic landslide displacement in each grid cell from the Northridge earthquake. The modeled displacements are then compared with the digital inventory of landslides triggered by the Northridge earthquake to construct a probability curve relating predicted displacement to probability of failure. This probability function can be applied to predict and map the spatial variability in failure probability in any ground-shaking conditions of interest. We anticipate that this mapping procedure will be used to construct seismic landslide hazard maps that will assist in emergency preparedness planning and in making rational decisions regarding development and construction in areas susceptible to seismic slope failure.

Quantifying the uncertainty in site amplification modeling and its effects on site-specific seismic-hazard estimation in the upper Mississippi embayment and adjacent areas

USGS Publications Warehouse

Cramer, C.H.

2006-01-01

The Mississippi embayment, located in the central United States, and its thick deposits of sediments (over 1 km in places) have a large effect on earthquake ground motions. Several previous studies have addressed how these thick sediments might modify probabilistic seismic-hazard maps. The high seismic hazard associated with the New Madrid seismic zone makes it particularly important to quantify the uncertainty in modeling site amplification to better represent earthquake hazard in seismic-hazard maps. The methodology of the Memphis urban seismic-hazard-mapping project (Cramer et al., 2004) is combined with the reference profile approach of Toro and Silva (2001) to better estimate seismic hazard in the Mississippi embayment. Improvements over previous approaches include using the 2002 national seismic-hazard model, fully probabilistic hazard calculations, calibration of site amplification with improved nonlinear soil-response estimates, and estimates of uncertainty. Comparisons are made with the results of several previous studies, and estimates of uncertainty inherent in site-amplification modeling for the upper Mississippi embayment are developed. I present new seismic-hazard maps for the upper Mississippi embayment with the effects of site geology incorporating these uncertainties.

Seismic-zonation of Port-au-Prince using pixel- and object-based imaging analysis methods on ASTER GDEM

USGS Publications Warehouse

Yong, A.; Hough, S.E.; Cox, B.R.; Rathje, E.M.; Bachhuber, J.; Dulberg, R.; Hulslander, D.; Christiansen, L.; Abrams, M.J.

2011-01-01

We report about a preliminary study to evaluate the use of semi-automated imaging analysis of remotely-sensed DEM and field geophysical measurements to develop a seismic-zonation map of Port-au-Prince, Haiti. For in situ data, Vs30 values are derived from the MASW technique deployed in and around the city. For satellite imagery, we use an ASTER GDEM of Hispaniola. We apply both pixel- and object-based imaging methods on the ASTER GDEM to explore local topography (absolute elevation values) and classify terrain types such as mountains, alluvial fans and basins/near-shore regions. We assign NEHRP seismic site class ranges based on available Vs30 values. A comparison of results from imagery-based methods to results from traditional geologic-based approaches reveals good overall correspondence. We conclude that image analysis of RS data provides reliable first-order site characterization results in the absence of local data and can be useful to refine detailed site maps with sparse local data. ?? 2011 American Society for Photogrammetry and Remote Sensing.

Seismic hazard map of the western hemisphere

USGS Publications Warehouse

Shedlock, K.M.; Tanner, J.G.

1999-01-01

Vulnerability to natural disasters increases with urbanization and development of associated support systems (reservoirs, power plants, etc.). Catastrophic earthquakes account for 60% of worldwide casualties associated with natural disasters. Economic damage from earthquakes is increasing, even in technologically advanced countries with some level of seismic zonation, as shown by the 1989 Loma Prieta, CA ($6 billion), 1994 Northridge, CA ($ 25 billion), and 1995 Kobe, Japan (> $ 100 billion) earthquakes. The growth of megacities in seismically active regions around the world often includes the construction of seismically unsafe buildings and infrastructures, due to an insufficient knowledge of existing seismic hazard. Minimization of the loss of life, property damage, and social and economic disruption due to earthquakes depends on reliable estimates of seismic hazard. National, state, and local governments, decision makers, engineers, planners, emergency response organizations, builders, universities, and the general public require seismic hazard estimates for land use planning, improved building design and construction (including adoption of building construction codes), emergency response preparedness plans, economic forecasts, housing and employment decisions, and many more types of risk mitigation. The seismic hazard map of the Americas is the concatenation of various national and regional maps, involving a suite of approaches. The combined maps and documentation provide a useful global seismic hazard framework and serve as a resource for any national or regional agency for further detailed studies applicable to their needs. This seismic hazard map depicts Peak Ground Acceleration (PGA) with a 10% chance of exceedance in 50 years for the western hemisphere. PGA, a short-period ground motion parameter that is proportional to force, is the most commonly mapped ground motion parameter because current building codes that include seismic provisions specify the horizontal force a building should be able to withstand during an earthquake. This seismic hazard map of the Americas depicts the likely level of short-period ground motion from earthquakes in a fifty-year window. Short-period ground motions effect short-period structures (e.g., one-to-two story buildings). The largest seismic hazard values in the western hemisphere generally occur in areas that have been, or are likely to be, the sites of the largest plate boundary earthquakes. Although the largest earthquakes ever recorded are the 1960 Chile and 1964 Alaska subduction zone earthquakes, the largest seismic hazard (PGA) value in the Americas is in Southern California (U.S.), along the San Andreas fault.

Seismic Microzonation of Breginjski Kot (NW Slovenia) Based on Detailed Engineering Geological Mapping

PubMed Central

2013-01-01

Breginjski kot is among the most endangered seismic zones in Slovenia with the seismic hazard assessed to intensity IX MSK and the design ground acceleration of 0.250 g, both for 500-year return period. The most destructive was the 1976 Friuli Mw = 6.4 earthquake which had maximum intensity VIII-IX. Since the previous microzonation of the area was based solely on the basic geological map and did not include supplementary field research, we have performed a new soil classification of the area. First, a detailed engineering geological mapping in scale 1 : 5.000 was conducted. Mapped units were described in detail and some of them interpreted anew. Stiff sites are composed of hard to medium-hard rocks which were subjected to erosion mainly evoked by glacial and postglacial age. At that time a prominent topography was formed and different types of sediments were deposited in valleys by mass flows. A distinction between sediments and weathered rocks, their exact position, and thickness are of significant importance for microzonation. On the basis of geological mapping, a soil classification was carried out according to the Medvedev method (intensity increments) and the Eurocode 8 standard (soil factors) and two microzonation maps were prepared. The bulk of the studied area is covered by soft sediments and nine out of ten settlements are situated on them. The microzonation clearly points out the dependence of damage distribution in the case of 1976 Friuli earthquake to local site effects. PMID:24453884

An updated stress map of the continental United States reveals heterogeneous intraplate stress

NASA Astrophysics Data System (ADS)

Levandowski, Will; Herrmann, Robert B.; Briggs, Rich; Boyd, Oliver; Gold, Ryan

2018-06-01

Knowledge of the state of stress in Earth's crust is key to understanding the forces and processes responsible for earthquakes. Historically, low rates of natural seismicity in the central and eastern United States have complicated efforts to understand intraplate stress, but recent improvements in seismic networks and the spread of human-induced seismicity have greatly improved data coverage. Here, we compile a nationwide stress map based on formal inversions of focal mechanisms that challenges the idea that deformation in continental interiors is driven primarily by broad, uniform stress fields derived from distant plate boundaries. Despite plate-boundary compression, extension dominates roughly half of the continent, and second-order forces related to lithospheric structure appear to control extension directions. We also show that the states of stress in several active eastern United States seismic zones differ significantly from those of surrounding areas and that these anomalies cannot be explained by transient processes, suggesting that earthquakes are focused by persistent, locally derived sources of stress. Such spatially variable intraplate stress appears to justify the current, spatially variable estimates of seismic hazard. Future work to quantify sources of stress, stressing-rate magnitudes and their relationship with strain and earthquake rates could allow prospective mapping of intraplate hazard.

Identification of Sungai Batu Sediment using 2-D Resistivity Imaging and Seismic Refraction Methods for Ancient River Mapping at Kedah, Malaysia

NASA Astrophysics Data System (ADS)

Andika, F.; Saad, R.; Saidin, M. M.; Muztaza, N. M.; Amsir

2018-04-01

Sungai Batu is an earliest civilization in Southeast Asia with evidenced by the discovery of riverside jetty, iron smelting, and ritual monuments. The evidences can lead to prediction of buried river caused by geological and sedimentation process. This study was conducted to study sediment deposit characteristic and to map thickness of the sediments using 2-D resistivity imaging and seismic refraction for ancient river mapping. A total of thirty, 2-D resistivity and nine seismic survey lines were conducted at the study area. Four of the lines R1-R4 and S1-S4 were correlated and validated with existing on site boreholes BH1-BH4 to identify sediment type and thickness. The validated values applied to the remaining survey lines which no borehole record to map the subsurface of the study area. Based on the results, Sungai Batu area consist of clay with resistivity value of 6.6-25.9 Ω.m and velocity value of 716.9-1606.9 m/s; sandy clay with resistivity value of 6-265.1 Ω.m and velocity value of 1003.6-1901.4 m/s; while shale was identified with resistivity value of >668.6 Ω.m and velocity value of >2051.7 m/s. Boundary between clay/sandy clay with shale was identified with resistivity value of 314 Ω.m and velocity value of 1822 m/s. The integration of the 2-D resistivity and seismic refraction identified that the thickness of Sungai Batu sediment is 0-150 m and Sungai Batu ancient river was successfully map based on thickness of sediment which is >45 m.

Probabilistic Seismic Hazard Maps for Ecuador

NASA Astrophysics Data System (ADS)

Mariniere, J.; Beauval, C.; Yepes, H. A.; Laurence, A.; Nocquet, J. M.; Alvarado, A. P.; Baize, S.; Aguilar, J.; Singaucho, J. C.; Jomard, H.

2017-12-01

A probabilistic seismic hazard study is led for Ecuador, a country facing a high seismic hazard, both from megathrust subduction earthquakes and shallow crustal moderate to large earthquakes. Building on the knowledge produced in the last years in historical seismicity, earthquake catalogs, active tectonics, geodynamics, and geodesy, several alternative earthquake recurrence models are developed. An area source model is first proposed, based on the seismogenic crustal and inslab sources defined in Yepes et al. (2016). A slightly different segmentation is proposed for the subduction interface, with respect to Yepes et al. (2016). Three earthquake catalogs are used to account for the numerous uncertainties in the modeling of frequency-magnitude distributions. The hazard maps obtained highlight several source zones enclosing fault systems that exhibit low seismic activity, not representative of the geological and/or geodetical slip rates. Consequently, a fault model is derived, including faults with an earthquake recurrence model inferred from geological and/or geodetical slip rate estimates. The geodetical slip rates on the set of simplified faults are estimated from a GPS horizontal velocity field (Nocquet et al. 2014). Assumptions on the aseismic component of the deformation are required. Combining these alternative earthquake models in a logic tree, and using a set of selected ground-motion prediction equations adapted to Ecuador's different tectonic contexts, a mean hazard map is obtained. Hazard maps corresponding to the percentiles 16 and 84% are also derived, highlighting the zones where uncertainties on the hazard are highest.

Multisensor of Remotely Sensed Data for Characterizing Seismotectonic Activities in Malaysia

NASA Astrophysics Data System (ADS)

Abu Bakar, Rabieahtul; Azahari Razak, Khamarrul; Anuar Jamaludin, Tajul; Tongkul, Felix; Mohamad, Zakaria; Ramli, Zamri; Abd Manap, Mohamad; Rahman, Muhammad Zulkarnain Abdul

2015-04-01

Seismically induced events pose serious hazards yet are difficult to predict. Despite remarkable efforts of mapping, monitoring and modelling of such great events at regional or local scales, the understanding of the processes in the Earth's dynamic system remains elusive. Although Malaysia is in a relatively low seismic hazard zone, the current trend and pattern of seismotectonic activities triggered a series of fundamental study to better understand the relationship between the earthquakes, recent tectonics and seismically active fault zones. Several conventional mapping techniques have been intensively used but shown some limitations. Remote sensing is the preferable mean to quantify the seismic activity accurately in a larger area within a short period. Still, only few of such studies have been carried out in this subduction region. Characterization of seismotectonic activities from space in a tropical environment is very challenging given the complexity of its physiographic, climatic, geologic conditions and anthropogenic activities. There are many factors controlling the success rate of the implementation mainly due to the lack of historical earthquakes, geomorphological evidence, and proper identification of regional tectonic patterns. In this study, we aim at providing better insight to extract and characterize seismotectonic activities by integrating passive and active remotely-sensed data, geodetic data, historical records, GIS-based data analysis and in-situ measurements as well quantify them based on field investigation and expert knowledge. It is crucial to perform spatiotemporal analysis of its activities in the most seismically induced region in North-Western Sabah. A comprehensive geodatabase of seismotectonic events are developed and allowed us to analyse the spatiotemporal activities. A novelty of object-based image method for extracting tropical seismically active faults and related seismotectonic features are introduced and evaluated. We aim to develop the exchangeable and transferable rule-set with optimal parameterization for such aforementioned tasks. A geomorphometric-based remotely sensed approach is used to understand the tectonic geomorphology in processes affecting the environment at different spatial scales. As a result of this study, questions related to cascading natural disasters, e.g. landslides can be quantitatively answered. Development and applications of seismically induced landslide hazard and risk zonation at different scales are conceptually presented and critically discussed. So far, quantification evaluation of uncertainties associated to spatial seismic hazard and risks prediction remains very challenging to understand and it is an interest of on-going research. In the near-future, it is crucial to address the changes of climate and land-use-land-cover in relation to temporal and spatial pattern of seismically induced landslides. It is also important to assess, model and incorporate the changes due to natural disasters into a sustainable risk management. As a conclusion, the characteristics, development and function of tectonic movement, as one of the components for geomorphological process-response system is crucial for a regional seismic study. With newly emerging multi-sensor of remotely sensed data coupled with the satellite positioning system promises a better mapping and monitoring tool for seismotectonic activities in such a way that it can be used to map, monitor, and model related seismically induced processes for a comprehensive hazard and associated risk assessment.

Synthesis of regional crust and upper-mantle structure from seismic and gravity data

NASA Technical Reports Server (NTRS)

Alexander, S. S.; Lavin, P. M.

1979-01-01

Available seismic and ground based gravity data are combined to infer the three dimensional crust and upper mantle structure in selected regions. This synthesis and interpretation proceeds from large-scale average models suitable for early comparison with high-altitude satellite potential field data to more detailed delineation of structural boundaries and other variations that may be significant in natural resource assessment. Seismic and ground based gravity data are the primary focal point, but other relevant information (e.g. magnetic field, heat flow, Landsat imagery, geodetic leveling, and natural resources maps) is used to constrain the structure inferred and to assist in defining structural domains and boundaries. The seismic data consists of regional refraction lines, limited reflection coverage, surface wave dispersion, teleseismic P and S wave delay times, anelastic absorption, and regional seismicity patterns. The gravity data base consists of available point gravity determinations for the areas considered.

2008 United States National Seismic Hazard Maps

USGS Publications Warehouse

Petersen, M.D.; ,

2008-01-01

The U.S. Geological Survey recently updated the National Seismic Hazard Maps by incorporating new seismic, geologic, and geodetic information on earthquake rates and associated ground shaking. The 2008 versions supersede those released in 1996 and 2002. These maps are the basis for seismic design provisions of building codes, insurance rate structures, earthquake loss studies, retrofit priorities, and land-use planning. Their use in design of buildings, bridges, highways, and critical infrastructure allows structures to better withstand earthquake shaking, saving lives and reducing disruption to critical activities following a damaging event. The maps also help engineers avoid costs from over-design for unlikely levels of ground motion.

Seismic Hazard Assessment for a Characteristic Earthquake Scenario: Probabilistic-Deterministic Method

NASA Astrophysics Data System (ADS)

mouloud, Hamidatou

2016-04-01

The objective of this paper is to analyze the seismic activity and the statistical treatment of seismicity catalog the Constantine region between 1357 and 2014 with 7007 seismic event. Our research is a contribution to improving the seismic risk management by evaluating the seismic hazard in the North-East Algeria. In the present study, Earthquake hazard maps for the Constantine region are calculated. Probabilistic seismic hazard analysis (PSHA) is classically performed through the Cornell approach by using a uniform earthquake distribution over the source area and a given magnitude range. This study aims at extending the PSHA approach to the case of a characteristic earthquake scenario associated with an active fault. The approach integrates PSHA with a high-frequency deterministic technique for the prediction of peak and spectral ground motion parameters in a characteristic earthquake. The method is based on the site-dependent evaluation of the probability of exceedance for the chosen strong-motion parameter. We proposed five sismotectonique zones. Four steps are necessary: (i) identification of potential sources of future earthquakes, (ii) assessment of their geological, geophysical and geometric, (iii) identification of the attenuation pattern of seismic motion, (iv) calculation of the hazard at a site and finally (v) hazard mapping for a region. In this study, the procedure of the earthquake hazard evaluation recently developed by Kijko and Sellevoll (1992) is used to estimate seismic hazard parameters in the northern part of Algeria.

Mapping apparent stress and energy radiation over fault zones of major earthquakes

USGS Publications Warehouse

McGarr, A.; Fletcher, Joe B.

2002-01-01

Using published slip models for five major earthquakes, 1979 Imperial Valley, 1989 Loma Prieta, 1992 Landers, 1994 Northridge, and 1995 Kobe, we produce maps of apparent stress and radiated seismic energy over their fault surfaces. The slip models, obtained by inverting seismic and geodetic data, entail the division of the fault surfaces into many subfaults for which the time histories of seismic slip are determined. To estimate the seismic energy radiated by each subfault, we measure the near-fault seismic-energy flux from the time-dependent slip there and then multiply by a function of rupture velocity to obtain the corresponding energy that propagates into the far-field. This function, the ratio of far-field to near-fault energy, is typically less than 1/3, inasmuch as most of the near-fault energy remains near the fault and is associated with permanent earthquake deformation. Adding the energy contributions from all of the subfaults yields an estimate of the total seismic energy, which can be compared with independent energy estimates based on seismic-energy flux measured in the far-field, often at teleseismic distances. Estimates of seismic energy based on slip models are robust, in that different models, for a given earthquake, yield energy estimates that are in close agreement. Moreover, the slip-model estimates of energy are generally in good accord with independent estimates by others, based on regional or teleseismic data. Apparent stress is estimated for each subfault by dividing the corresponding seismic moment into the radiated energy. Distributions of apparent stress over an earthquake fault zone show considerable heterogeneity, with peak values that are typically about double the whole-earthquake values (based on the ratio of seismic energy to seismic moment). The range of apparent stresses estimated for subfaults of the events studied here is similar to the range of apparent stresses for earthquakes in continental settings, with peak values of about 8 MPa in each case. For earthquakes in compressional tectonic settings, peak apparent stresses at a given depth are substantially greater than corresponding peak values from events in extensional settings; this suggests that crustal strength, inferred from laboratory measurements, may be a limiting factor. Lower bounds on shear stresses inferred from the apparent stress distribution of the 1995 Kobe earthquake are consistent with tectonic-stress estimates reported by Spudich et al. (1998), based partly on slip-vector rake changes.

Earthquake Building Damage Mapping Based on Feature Analyzing Method from Synthetic Aperture Radar Data

NASA Astrophysics Data System (ADS)

An, L.; Zhang, J.; Gong, L.

2018-04-01

Playing an important role in gathering information of social infrastructure damage, Synthetic Aperture Radar (SAR) remote sensing is a useful tool for monitoring earthquake disasters. With the wide application of this technique, a standard method, comparing post-seismic to pre-seismic data, become common. However, multi-temporal SAR processes, are not always achievable. To develop a post-seismic data only method for building damage detection, is of great importance. In this paper, the authors are now initiating experimental investigation to establish an object-based feature analysing classification method for building damage recognition.

First USGS urban seismic hazard maps predict the effects of soils

USGS Publications Warehouse

Cramer, C.H.; Gomberg, J.S.; Schweig, E.S.; Waldron, B.A.; Tucker, K.

2006-01-01

Probabilistic and scenario urban seismic hazard maps have been produced for Memphis, Shelby County, Tennessee covering a six-quadrangle area of the city. The nine probabilistic maps are for peak ground acceleration and 0.2 s and 1.0 s spectral acceleration and for 10%, 5%, and 2% probability of being exceeded in 50 years. Six scenario maps for these three ground motions have also been generated for both an M7.7 and M6.2 on the southwest arm of the New Madrid seismic zone ending at Marked Tree, Arkansas. All maps include the effect of local geology. Relative to the national seismic hazard maps, the effect of the thick sediments beneath Memphis is to decrease 0.2 s probabilistic ground motions by 0-30% and increase 1.0 s probabilistic ground motions by ???100%. Probabilistic peak ground accelerations remain at levels similar to the national maps, although the ground motion gradient across Shelby County is reduced and ground motions are more uniform within the county. The M7.7 scenario maps show ground motions similar to the 5%-in-50-year probabilistic maps. As an effect of local geology, both M7.7 and M6.2 scenario maps show a more uniform seismic ground-motion hazard across Shelby County than scenario maps with constant site conditions (i.e., NEHRP B/C boundary).

Co- and post-seismic deformation for the 2014 Napa Valley Earthquake from Sentinel-1A interferometry

NASA Astrophysics Data System (ADS)

Elliott, J. R.; Wright, T. J.; Elliott, A. J.; González, P. J.; Hooper, A. J.; Larsen, Y.; Marinkovic, P.; Plain, M.; Walters, R. J.

2014-12-01

Here we present analysis of co- and post-seismic deformation for the 24 August 2014 Napa Valley Earthquake derived from Sentinel-1A interferometry. We use these to derive the co-seismic slip distribution and map the evolution of post-seismic afterslip. The 24 August 2014 Napa Valley earthquake was the first earthquake for which surface deformation was measured by Sentinel-1A, a new radar satellite launched by the European Space Agency on 3 April 2014, and operated by the European Commission's Copernicus program. Sentinel-1A reached its final operational orbit on 7 August, and fortuitously acquired a pre-earthquake image of the San Francisco Bay area on that day in StripMap mode. By comparing it with an image acquired on 31 August, we formed a co-seismic interferogram, which reveals the surface deformation that occurred during the earthquake and the first 7 days of the post-seismic period. We use this to constrain a simple elastic model of the co-seismic slip distribution; preliminary inversion results show that the slip at depth reached a peak of >1.5 m at a depth of ~4 km. Following the earthquake, Sentinel-1A has acquired further acquisitions in both StripMap and Interferometric Wide Swath modes. The first 12-day post-seismic StripMap interferogram shows a sharp discontinuity along the entire fault rupture, consistent with field observations of rapid afterslip. We will use the full time series from August to December to measure the spatio-temporal behaviour of the afterslip, and discuss the implications for the frictional properties of the fault. The results from Napa point to an exciting and impactful future for the Sentinel-1 radar constellation. By mid-2014, Sentinel-1A will be acquiring data systematically over all the seismic belts, and the launch of Sentinel-1B in 2016 will increase the temporal frequency of acquisitions. The data will be available free of charge and will transform our ability to conduct tectonic geodesy, particularly in remote areas of the planet or developing countries unable to afford dense ground-based GNSS networks.

A reliable simultaneous representation of seismic hazard and of ground shaking recurrence

NASA Astrophysics Data System (ADS)

Peresan, A.; Panza, G. F.; Magrin, A.; Vaccari, F.

2015-12-01

Different earthquake hazard maps may be appropriate for different purposes - such as emergency management, insurance and engineering design. Accounting for the lower occurrence rate of larger sporadic earthquakes may allow to formulate cost-effective policies in some specific applications, provided that statistically sound recurrence estimates are used, which is not typically the case of PSHA (Probabilistic Seismic Hazard Assessment). We illustrate the procedure to associate the expected ground motions from Neo-deterministic Seismic Hazard Assessment (NDSHA) to an estimate of their recurrence. Neo-deterministic refers to a scenario-based approach, which allows for the construction of a broad range of earthquake scenarios via full waveforms modeling. From the synthetic seismograms the estimates of peak ground acceleration, velocity and displacement, or any other parameter relevant to seismic engineering, can be extracted. NDSHA, in its standard form, defines the hazard computed from a wide set of scenario earthquakes (including the largest deterministically or historically defined credible earthquake, MCE) and it does not supply the frequency of occurrence of the expected ground shaking. A recent enhanced variant of NDSHA that reliably accounts for recurrence has been developed and it is applied to the Italian territory. The characterization of the frequency-magnitude relation can be performed by any statistically sound method supported by data (e.g. multi-scale seismicity model), so that a recurrence estimate is associated to each of the pertinent sources. In this way a standard NDSHA map of ground shaking is obtained simultaneously with the map of the corresponding recurrences. The introduction of recurrence estimates in NDSHA naturally allows for the generation of ground shaking maps at specified return periods. This permits a straightforward comparison between NDSHA and PSHA maps.

Seismic hazard assessment of the Kivu rift segment based on a new seismotectonic zonation model (western branch, East African Rift system)

NASA Astrophysics Data System (ADS)

Delvaux, Damien; Mulumba, Jean-Luc; Sebagenzi, Mwene Ntabwoba Stanislas; Bondo, Silvanos Fiama; Kervyn, François; Havenith, Hans-Balder

2017-10-01

In the frame of the Belgian GeoRisCA multi-risk assessment project focusing on the Kivu and northern Tanganyika rift region in Central Africa, a new probabilistic seismic hazard assessment has been performed for the Kivu rift segment in the central part of the western branch of the East African rift system. As the geological and tectonic setting of this region is incompletely known, especially the part lying in the Democratic Republic of the Congo, we compiled homogeneous cross-border tectonic and neotectonic maps. The seismic risk assessment is based on a new earthquake catalogue based on the ISC reviewed earthquake catalogue and supplemented by other local catalogues and new macroseismic epicenter data spanning 126 years, with 1068 events. The magnitudes have been homogenized to Mw and aftershocks removed. The final catalogue used for the seismic hazard assessment spans 60 years, from 1955 to 2015, with 359 events and a magnitude of completeness of 4.4. The seismotectonic zonation into 7 seismic source areas was done on the basis of the regional geological structure, neotectonic fault systems, basin architecture and distribution of thermal springs and earthquake epicenters. The Gutenberg-Richter seismic hazard parameters were determined by the least square linear fit and the maximum likelihood method. Seismic hazard maps have been computed using existing attenuation laws with the Crisis 2012 software. We obtained higher PGA values (475 years return period) for the Kivu rift region than the previous estimates. They also vary laterally in function of the tectonic setting, with the lowest value in the volcanically active Virunga - Rutshuru zone, highest in the currently non-volcanic parts of Lake Kivu, Rusizi valley and North Tanganyika rift zone, and intermediate in the regions flanking the axial rift zone.

Seismic Hazard Assessment of Tehran Based on Arias Intensity

NASA Astrophysics Data System (ADS)

Amiri, G. Ghodrati; Mahmoodi, H.; Amrei, S. A. Razavian

2008-07-01

In this paper probabilistic seismic hazard assessment of Tehran for Arias intensity parameter is done. Tehran is capital and most populated city of Iran. From economical, political and social points of view, Tehran is the most significant city of Iran. Since in the previous centuries, catastrophic earthquakes have occurred in Tehran and its vicinity, probabilistic seismic hazard assessment of this city for Arias intensity parameter is useful. Iso-intensity contour lines maps of Tehran on the basis of different attenuation relationships for different earthquake periods are plotted. Maps of iso-intensity points in the Tehran region are presented using proportional attenuation relationships for rock and soil beds for 2 hazard levels of 10% and 2% in 50 years. Seismicity parameters on the basis of historical and instrumental earthquakes for a time period that initiate from 4th century BC and ends in the present time are calculated using Tow methods. For calculation of seismicity parameters, the earthquake catalogue with a radius of 200 km around Tehran has been used. SEISRISKIII Software has been employed. Effects of different parameters such as seismicity parameters, length of fault rupture relationships and attenuation relationships are considered using Logic Tree.

Seismic Hazard Assessment of Tehran Based on Arias Intensity

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

Amiri, G. Ghodrati; Mahmoodi, H.; Amrei, S. A. Razavian

2008-07-08

In this paper probabilistic seismic hazard assessment of Tehran for Arias intensity parameter is done. Tehran is capital and most populated city of Iran. From economical, political and social points of view, Tehran is the most significant city of Iran. Since in the previous centuries, catastrophic earthquakes have occurred in Tehran and its vicinity, probabilistic seismic hazard assessment of this city for Arias intensity parameter is useful. Iso-intensity contour lines maps of Tehran on the basis of different attenuation relationships for different earthquake periods are plotted. Maps of iso-intensity points in the Tehran region are presented using proportional attenuation relationshipsmore » for rock and soil beds for 2 hazard levels of 10% and 2% in 50 years. Seismicity parameters on the basis of historical and instrumental earthquakes for a time period that initiate from 4th century BC and ends in the present time are calculated using Tow methods. For calculation of seismicity parameters, the earthquake catalogue with a radius of 200 km around Tehran has been used. SEISRISKIII Software has been employed. Effects of different parameters such as seismicity parameters, length of fault rupture relationships and attenuation relationships are considered using Logic Tree.« less

Challenges in assessing seismic hazard in intraplate Europe

NASA Astrophysics Data System (ADS)

Brooks, Edward; Stein, Seth; Liu, Mian; Camelbeeck, Thierry; Merino, Miguel; Landgraf, Angela; Hintersberger, Esther; Kübler, Simon

2016-04-01

Intraplate seismicity is often characterized by episodic, clustered and migrating earth- quakes and extended after-shock sequences. Can these observations - primarily from North America, China and Australia - usefully be applied to seismic hazard assessment for intraplate Europe? Existing assessments are based on instrumental and historical seismicity of the past c. 1000 years, as well as some data for active faults. This time span probably fails to capture typical large-event recurrence intervals of the order of tens of thousands of years. Palaeoseismology helps to lengthen the observation window, but preferentially produces data in regions suspected to be seismically active. Thus the expected maximum magnitudes of future earthquakes are fairly uncertain, possibly underestimated, and earthquakes are likely to occur in unexpected locations. These issues particularly arise in considering the hazards posed by low-probability events to both heavily populated areas and critical facilities. For example, are the variations in seismicity (and thus assumed seismic hazard) along the Rhine Graben a result of short sampling or are they real? In addition to a better assessment of hazards with new data and models, it is important to recognize and communicate uncertainties in hazard estimates. The more users know about how much confidence to place in hazard maps, the more effectively the maps can be used.

Seismic properties of the crust and uppermost mantle of North America

NASA Technical Reports Server (NTRS)

Braile, L. W.; Hinze, W. J.; Vonfrese, R. R. B.; Keller, G. R.

1983-01-01

Seismic refraction profiles for the North American continent were compiled. The crustal models compiled data on the upper mantle seismic velocity (P sub n), the crustal thickness (H sub c) and the average seismic velocity of the crystalline crust (V sub p). Compressional wave parameters were compared with shear wave data derived from surface wave dispersion models and indicate an average value for Poisson's ratio of 0.252 for the crust and of 0.273 for the uppermost mantle. Contour maps illustrate lateral variations in crustal thickness, upper mantle velocity and average seismic velocity of the crystalline crust. The distribution of seismic parameters are compared with a smoothed free air anomaly map of North America and indicate that a complidated mechanism of isostatic compensation exists for the North American continent. Several features on the seismic contour maps also correlate with regional magnetic anomalies.

Understanding Seismic Anisotropy in Hunt Well of Fort McMurray, Canada

NASA Astrophysics Data System (ADS)

Malehmir, R.; Schmitt, D. R.; Chan, J.

2014-12-01

Seismic imaging plays vital role in geothermal systems as a sustainable energy resource. In this paper, we acquired and processed zero-offset and walk-away VSP and logging as well as surface seismic in Athabasca oil sand area, Alberta. Seismic data were highly processed to make better image geothermal system. Through data processing, properties of natural fractures such as orientation and width were studied and high probable permeable zones were mapped along the deep drilled to the depth of 2363m deep into crystalline basement rocks. In addition to logging data, seismic data were processed to build a reliable image of underground. Velocity analysis in high resolution multi-component walk-away VSP informed us about the elastic anisotropy in place. Study of the natural and induced fracture as well as elastic anisotropy in the seismic data, led us to better map stress regime around the well bore. The seismic image and map of fractures optimizes enhanced geothermal stages through hydraulic stimulation. Keywords: geothermal, anisotropy, VSP, logging, Hunt well, seismic

Errors in Seismic Hazard Assessment are Creating Huge Human Losses

NASA Astrophysics Data System (ADS)

Bela, J.

2015-12-01

The current practice of representing earthquake hazards to the public based upon their perceived likelihood or probability of occurrence is proven now by the global record of actual earthquakes to be not only erroneous and unreliable, but also too deadly! Earthquake occurrence is sporadic and therefore assumptions of earthquake frequency and return-period are both not only misleading, but also categorically false. More than 700,000 people have now lost their lives (2000-2011), wherein 11 of the World's Deadliest Earthquakes have occurred in locations where probability-based seismic hazard assessments had predicted only low seismic low hazard. Unless seismic hazard assessment and the setting of minimum earthquake design safety standards for buildings and bridges are based on a more realistic deterministic recognition of "what can happen" rather than on what mathematical models suggest is "most likely to happen" such future huge human losses can only be expected to continue! The actual earthquake events that did occur were at or near the maximum potential-size event that either already had occurred in the past; or were geologically known to be possible. Haiti's M7 earthquake, 2010 (with > 222,000 fatalities) meant the dead could not even be buried with dignity. Japan's catastrophic Tohoku earthquake, 2011; a M9 Megathrust earthquake, unleashed a tsunami that not only obliterated coastal communities along the northern Japanese coast, but also claimed > 20,000 lives. This tsunami flooded nuclear reactors at Fukushima, causing 4 explosions and 3 reactors to melt down. But while this history of huge human losses due to erroneous and misleading seismic hazard estimates, despite its wrenching pain, cannot be unlived; if faced with courage and a more realistic deterministic estimate of "what is possible", it need not be lived again. An objective testing of the results of global probability based seismic hazard maps against real occurrences has never been done by the GSHAP team; even though the obvious inadequacy of the GSHAP map could have been established in the course of a simple check before the project completion. The doctrine of "psha exceptionalism" that created the maps can only be esponged by carefully examining the facts . . . which unfortunately include huge human losses!

Seismic hazard and seismic risk assessment based on the unified scaling law for earthquakes: Himalayas and adjacent regions

NASA Astrophysics Data System (ADS)

Nekrasova, A. K.; Kossobokov, V. G.; Parvez, I. A.

2015-03-01

For the Himalayas and neighboring regions, the maps of seismic hazard and seismic risk are constructed with the use of the estimates for the parameters of the unified scaling law for earthquakes (USLE), in which the Gutenberg-Richter law for magnitude distribution of seismic events within a given area is applied in the modified version with allowance for linear dimensions of the area, namely, log N( M, L) = A + B (5 - M) + C log L, where N( M, L) is the expected annual number of the earthquakes with magnitude M in the area with linear dimension L. The spatial variations in the parameters A, B, and C for the Himalayas and adjacent regions are studied on two time intervals from 1965 to 2011 and from 1980 to 2011. The difference in A, B, and C between these two time intervals indicates that seismic activity experiences significant variations on a scale of a few decades. With a global consideration of the seismic belts of the Earth overall, the estimates of coefficient A, which determines the logarithm of the annual average frequency of the earthquakes with a magnitude of 5.0 and higher in the zone with a linear dimension of 1 degree of the Earth's meridian, differ by a factor of 30 and more and mainly fall in the interval from -1.1 to 0.5. The values of coefficient B, which describes the balance between the number of earthquakes with different magnitudes, gravitate to 0.9 and range from less than 0.6 to 1.1 and higher. The values of coefficient C, which estimates the fractal dimension of the local distribution of epicenters, vary from 0.5 to 1.4 and higher. In the Himalayas and neighboring regions, the USLE coefficients mainly fall in the intervals of -1.1 to 0.3 for A, 0.8 to 1.3 for B, and 1.0 to 1.4 for C. The calculations of the local value of the expected peak ground acceleration (PGA) from the maximal expected magnitude provided the necessary basis for mapping the seismic hazards in the studied region. When doing this, we used the local estimates of the magnitudes which, according to USLE, corresponded to the probability of exceedance 1% and 10% during 50 years or, if the reliable estimate is absent, the maximal magnitudes reported during the instrumental period. As a result, the seismic hazard maps for the Himalayas and the adjacent regions in terms of standard seismic zoning were constructed. Based on these calculations, in order to exemplify the method, we present a series of seismic risk maps taking into account the population density prone to seismic hazard and the dependence of the risk on the vulnerability as a function of population density.

Seismic facies analysis based on self-organizing map and empirical mode decomposition

NASA Astrophysics Data System (ADS)

Du, Hao-kun; Cao, Jun-xing; Xue, Ya-juan; Wang, Xing-jian

2015-01-01

Seismic facies analysis plays an important role in seismic interpretation and reservoir model building by offering an effective way to identify the changes in geofacies inter wells. The selections of input seismic attributes and their time window have an obvious effect on the validity of classification and require iterative experimentation and prior knowledge. In general, it is sensitive to noise when waveform serves as the input data to cluster analysis, especially with a narrow window. To conquer this limitation, the Empirical Mode Decomposition (EMD) method is introduced into waveform classification based on SOM. We first de-noise the seismic data using EMD and then cluster the data using 1D grid SOM. The main advantages of this method are resolution enhancement and noise reduction. 3D seismic data from the western Sichuan basin, China, are collected for validation. The application results show that seismic facies analysis can be improved and better help the interpretation. The powerful tolerance for noise makes the proposed method to be a better seismic facies analysis tool than classical 1D grid SOM method, especially for waveform cluster with a narrow window.

Earthquake hazard assessment in the Zagros Orogenic Belt of Iran using a fuzzy rule-based model

NASA Astrophysics Data System (ADS)

Farahi Ghasre Aboonasr, Sedigheh; Zamani, Ahmad; Razavipour, Fatemeh; Boostani, Reza

2017-08-01

Producing accurate seismic hazard map and predicting hazardous areas is necessary for risk mitigation strategies. In this paper, a fuzzy logic inference system is utilized to estimate the earthquake potential and seismic zoning of Zagros Orogenic Belt. In addition to the interpretability, fuzzy predictors can capture both nonlinearity and chaotic behavior of data, where the number of data is limited. In this paper, earthquake pattern in the Zagros has been assessed for the intervals of 10 and 50 years using fuzzy rule-based model. The Molchan statistical procedure has been used to show that our forecasting model is reliable. The earthquake hazard maps for this area reveal some remarkable features that cannot be observed on the conventional maps. Regarding our achievements, some areas in the southern (Bandar Abbas), southwestern (Bandar Kangan) and western (Kermanshah) parts of Iran display high earthquake severity even though they are geographically far apart.

High-resolution diapycnal mixing map of the Alboran Sea thermocline from seismic reflection images

NASA Astrophysics Data System (ADS)

Mojica, Jhon F.; Sallarès, Valentí; Biescas, Berta

2018-06-01

The Alboran Sea is a dynamically active region where the salty and warm Mediterranean water first encounters the incoming milder and cooler Atlantic water. The interaction between these two water masses originates a set of sub-mesoscale structures and a complex sequence of processes that entail mixing close to the thermocline. Here we present a high-resolution map of the diapycnal diffusivity around the thermocline depth obtained using acoustic data recorded with a high-resolution multichannel seismic system. The map reveals a patchy thermocline, with spots of strong diapycnal mixing juxtaposed with areas of weaker mixing. The patch size is of a few kilometers in the horizontal scale and of 10-15 m in the vertical one. The comparison of the obtained maps with the original acoustic images shows that mixing tends to concentrate in areas where internal waves, which are ubiquitous in the surveyed area, become unstable and shear instabilities develop, enhancing energy transfer towards the turbulent regime. These results are also compared with others obtained using more conventional oceanographic probes. The values estimated based on the seismic data are within the ranges of values obtained from oceanographic data analysis, and they are also consistent with reference theoretical values. Overall, our results demonstrate that high-resolution seismic systems allow the remote quantification of mixing at the thermocline depth with unprecedented resolution.

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

Burrell, J.; Luheshi, M.; Mackenzie, A.

Gyda field (operated by BP) is located in Block 2/1 of the Norwegian outer continental shelf. The reservoir comprises a thin, wedge-shaped Upper Jurassic sand, overlain by Lower Cretaceous mudstones. For field development, it is necessary to accurately map a laterally discontinuous high-porosity zone and thus to help site well locations. To this end, it was decided to invert the 3-D seismic data set over the field to the seismic attribute of absolute acoustic impedance (AAI). This was based on the observation that there is a good correlation between porosity and AII derived from well logs. Comparisons of core porosity,more » log-derived porosity, and seismic-derived porosity at several well locations showed this technique to be generally satisfactory. An additional problem in Gyda is the detection of the truncation edge of the reservoir along the southeastern part of the field. Deterministic methods based on AAI and on forward seismic modeling were not able to unambiguously define the edge of the reservoir. The truncation of th reservoir is not clear on normal seismic amplitude displays. In order to investigate the zone where the reservoir interval changes form sand to shale, certain special seismic attributes were computer over a gate of seismic data covering the top reservoir reflection. These attributes represented the energy, phase, and frequency content of the gate of seismic data. The area investigated was between wells where the reservoir sand was known to pinch out. These attributes were clustered using the statistical technique of projection pursuit. The cluster map correlates with the observations from the wells in this area of the field and appears to show the edge of the effective reservoir in the field.« less

Focal Mechanisms of Recent Earthquakes in the Southern Korean Peninsula

NASA Astrophysics Data System (ADS)

Park, J.; Kim, W.; Chung, T.; Baag, C.; Ree, J.

2005-12-01

There has been a lack of seismic data in the Korean Peninsula mainly because it is in a seismically stable area within the Eurasian plate (or Amurian microplate) and because a network of seismic stations has been poor until recently. Consequently, first motion studies on the peninsula showed a large uncertainty or covered only local areas. Also, a tectonic province map constructed based on pre-Cenozoic tectonic events in Korea has been used for a seismic zonation. To solve these problems, we made focal mechanism solutions for 71 earthquakes (ML = 1.9 to 5.2) occurred in and around the peninsula from 1999 to 2004 and collected by a new dense seismic network established since 1995. For this, we relocated the hypocenters and obtained fault plane solutions with errors of fault parameter less than 15° from the data set of 1,270 clear P-wave polarities and from 46 SH/P amplitude ratios. The focal mechanism solutions show that subhorizontal ENE P- and subhorizontal NNW T-axes are predominant, representing the common direction of P- and T-axes within the Amurian plate. The faulting mechanisms are mostly strike-slip faulting or strike-slip-dominant-oblique-slip faulting with a reverse-slip component, although normal-slip-dominant-oblique-slip faultings occur locally probably due to a local reorientation of stress. These results incorporated with those from the kinematic studies of the Quaternary faults imply that NNE-striking faults (dextral strike-slip or oblique-slip with a reverse-slip component) are highly likely to generate earthquakes in South Korea. The spatial distribution of the maximum horizontal stress direction and faulting types does not correlate with the preexisting tectonic province map of Korea, and a new construction of seismic zonation map is required for a better seismic evaluation.

Mapping the Influence of Prior Tectonism on Seismicity in the Central and Eastern US

NASA Astrophysics Data System (ADS)

Boyd, O. S.; Levandowski, W.; Ramirez-Guzman, L.; Zellman, M.; Briggs, R.

2015-12-01

From the Atlantic margin to the Rockies, most earthquakes in the central and eastern U.S. occur in ancient tectonic zones, yet many such features have been historically quiescent. If all intraplate stress were transferred from plate boundaries or bases, the stress field would be broadly uniform, with all well-oriented faults equally likely to slip. But faults are not the only product of tectonism; intrusions, metamorphism, or any number of other alterations may modify crustal and/or upper mantle density, leaving behind lithostatic pressure gradients that can locally elevate or reduce stress on faults. With data provided by Earthscope, we are working to map lithospheric density across the U.S. and to quantify gravitational body-forces using analytical and finite-element methods. Regional-scale 3D models show that gravitational forces focus seismicity and reorient principal stress both in the New Madrid seismic zone and the western Great Plains. Sedimentary fill and low elevation encourage Reelfoot Rift-normal contraction, yet along-strike variations in lower crustal density rotate body-forces beneath New Madrid to interfere constructively with far-field compression, augmenting differential stress by 5-10 MPa. On the plains of SE Colorado and SE Wyoming, the Cheraw and Wheatland/Whalen faults collocate with multiply reactivated Proterozoic sutures, enigmatic Quaternary extension, and focused seismicity with regionally anomalous NW-SE moment tensor T-axes. Earthscope data help reveal anomalously buoyant lower crust beneath each suture -­- which we hypothesize reflects hydration by Farallon slab-derived fluids that have preferentially migrated along ancient fracture networks -- that generates 10 MPa of localized suture-normal tension, consistent with geomorphic strain- and seismic stress-indicators. As continent-wide seismic models emerge from Earthscope data, we will continue to map regions where inherited structures encourage intraplate seismicity.

California Fault Parameters for the National Seismic Hazard Maps and Working Group on California Earthquake Probabilities 2007

USGS Publications Warehouse

Wills, Chris J.; Weldon, Ray J.; Bryant, W.A.

2008-01-01

This report describes development of fault parameters for the 2007 update of the National Seismic Hazard Maps and the Working Group on California Earthquake Probabilities (WGCEP, 2007). These reference parameters are contained within a database intended to be a source of values for use by scientists interested in producing either seismic hazard or deformation models to better understand the current seismic hazards in California. These parameters include descriptions of the geometry and rates of movements of faults throughout the state. These values are intended to provide a starting point for development of more sophisticated deformation models which include known rates of movement on faults as well as geodetic measurements of crustal movement and the rates of movements of the tectonic plates. The values will be used in developing the next generation of the time-independent National Seismic Hazard Maps, and the time-dependant seismic hazard calculations being developed for the WGCEP. Due to the multiple uses of this information, development of these parameters has been coordinated between USGS, CGS and SCEC. SCEC provided the database development and editing tools, in consultation with USGS, Golden. This database has been implemented in Oracle and supports electronic access (e.g., for on-the-fly access). A GUI-based application has also been developed to aid in populating the database. Both the continually updated 'living' version of this database, as well as any locked-down official releases (e.g., used in a published model for calculating earthquake probabilities or seismic shaking hazards) are part of the USGS Quaternary Fault and Fold Database http://earthquake.usgs.gov/regional/qfaults/ . CGS has been primarily responsible for updating and editing of the fault parameters, with extensive input from USGS and SCEC scientists.

ROSSMAP; Regional Seismic Stratigraphic Correlations in the Victoria Land Basin and the Timing of Rifting Episodes

NASA Astrophysics Data System (ADS)

Davy, B. W.; Henrys, S. A.; Wilson, T. J.; Fielding, C. R.; Levy, R. H.; Andrill Mis-Science Team

2010-12-01

ROSSMAP aims to produce a new series of digital seismic stratigraphic and structural maps for the Ross Sea region, and develop reconstructions of past sedimentary volumes and paleo-bathymetry that will be used in numerical models to help identify tectonic and climate feedbacks. In particular, ROSSMAP will define targets for future drilling initiatives in the Ross Sea region, and provide a legacy of web-based electronic databases that will be available to other researcher. Interpretation in the Victoria Land Basin (VLB) has focused on establishing links to new and existing drill holes. Several regional seismic reflectors were mapped throughout the southern portion of the Victoria Land Basin (VLB) and are tied to the ANDRILL McMurdo Sound drill cores. The age of one prominent reflector (Ri - red, correlative with RSU-2) is 4.7-4.3 Ma based on a tie to AND-1B and extensively mapped in the VLB. Mapping, together with quantitative biostratigraphic correlation techniques, indicates that the red reflector is associated with relative sea-level fall resulting from ice-sheet growth and/or local tectonic uplift. Correlative sediments preserved in AND-1B indicate regional climatic warmth, which suggests that the red reflector is more likely related to a tectonic event. Furthermore, the onset of sediment accumulation at CIROS-2 post-dates 4.5 Ma, suggesting that local subsidence and creation of accommodation space began at this time. Two other stratigraphic horizons (Rh and Rg) have been extensively mapped where seismic data image above the seafloor multiple. Reflector Rh (dark green and correlative with RSU-4a marks a basin-wide unconformity. Near the western margin of the Victoria Land Basin, this horizon is a marked angular discordance with angularity increasing westward. In AND-1B Rh is correlated with the base of a ~180-m-thick interval of late Miocene-early Pliocene, pyrite-cemented, high-velocity volcanic sandstone and mudstone. Volcanic rocks in a tongue extending from beneath White Island have been mapped at the dark green horizon in ROSSMAP seismic data data. If a new maximum age for White Island of 7.6 Ma is adopted, then this provides an approximate estimate for the age of Rh. Rg (light green and correlative with RSU-5) is a regionally extensive discontinuity correlated with the base of a 150-m-thick, high-velocity (3000 ms-1) interval of diamictite cycles in AND-1B and the base of a similarly thick diamictite dominated sequences in AND-2A. In AND-1B, 40Ar/39Ar dates on ashes beneath Rg indicate that this discontinuity is <13.8 Ma. In regional mapping Rg marks the onset of renewed rifting (Terror Rift) in the VLB but also may coincide with major global cooling associated with Mi3 event.

Time-dependent seismic hazard analysis for the Greater Tehran and surrounding areas

NASA Astrophysics Data System (ADS)

Jalalalhosseini, Seyed Mostafa; Zafarani, Hamid; Zare, Mehdi

2018-01-01

This study presents a time-dependent approach for seismic hazard in Tehran and surrounding areas. Hazard is evaluated by combining background seismic activity, and larger earthquakes may emanate from fault segments. Using available historical and paleoseismological data or empirical relation, the recurrence time and maximum magnitude of characteristic earthquakes for the major faults have been explored. The Brownian passage time (BPT) distribution has been used to calculate equivalent fictitious seismicity rate for major faults in the region. To include ground motion uncertainty, a logic tree and five ground motion prediction equations have been selected based on their applicability in the region. Finally, hazard maps have been presented.

Centrality in earthquake multiplex networks

NASA Astrophysics Data System (ADS)

Lotfi, Nastaran; Darooneh, Amir Hossein; Rodrigues, Francisco A.

2018-06-01

Seismic time series has been mapped as a complex network, where a geographical region is divided into square cells that represent the nodes and connections are defined according to the sequence of earthquakes. In this paper, we map a seismic time series to a temporal network, described by a multiplex network, and characterize the evolution of the network structure in terms of the eigenvector centrality measure. We generalize previous works that considered the single layer representation of earthquake networks. Our results suggest that the multiplex representation captures better earthquake activity than methods based on single layer networks. We also verify that the regions with highest seismological activities in Iran and California can be identified from the network centrality analysis. The temporal modeling of seismic data provided here may open new possibilities for a better comprehension of the physics of earthquakes.

New seismic hazard maps for Puerto Rico and the U.S. Virgin Islands

USGS Publications Warehouse

Mueller, C.; Frankel, A.; Petersen, M.; Leyendecker, E.

2010-01-01

The probabilistic methodology developed by the U.S. Geological Survey is applied to a new seismic hazard assessment for Puerto Rico and the U.S. Virgin Islands. Modeled seismic sources include gridded historical seismicity, subduction-interface and strike-slip faults with known slip rates, and two broad zones of crustal extension with seismicity rates constrained by GPS geodesy. We use attenuation relations from western North American and worldwide data, as well as a Caribbean-specific relation. Results are presented as maps of peak ground acceleration and 0.2- and 1.0-second spectral response acceleration for 2% and 10% probabilities of exceedance in 50 years (return periods of about 2,500 and 500 years, respectively). This paper describes the hazard model and maps that were balloted by the Building Seismic Safety Council and recommended for the 2003 NEHRP Provisions and the 2006 International Building Code. ?? 2010, Earthquake Engineering Research Institute.

New insights on the seismic hazard in the Balkans inferred from GPS

NASA Astrophysics Data System (ADS)

D'Agostino, Nicola; Métois, Marianne; Avallone, Antonio; Chamot-Rooke, Nicolas

2014-05-01

The Balkans region sits at the transition between stable Eurasia and highly straining continental Eastern Mediterranean, resulting in a widespread seismicity and high seismic hazard. Because of intensive human and economic development over the last decades, the vulnerability has increased in the region faster than the progress in seismic hazard assessments. Opposite to the relatively good understanding of the seismicity in plate boundaries contexts, the seismic hazard is poorly known in the regions of distributed continental deformation like the Balkan region and is often underestimated (England and Jackson, 2011). Current seismic hazard assessments are based on the historical and instrumental catalogues. However, the completeness interval of the historical data bases may be below the average recurrence of individual seismogenic structures. In addition, relatively sparse seismological networks in the region and limited cross-border seismic data exchanges cast doubts in seismotectonic interpretation and challenge our understanding of seismic and geodynamic processes. This results in a inhomogeneous knowledge of the seismic hazard of the region to date. Geodetic measurements have the capability to contribute to seismic hazard by mapping the field of current active deformation and translating it into estimates of the seismogenic potential. With simple assumptions, measurements of crustal deformation can be translated in estimates of the average frequency and magnitude of the largest events and assessments of the aseismic deformation. GPS networks in the Balkans have been growing during the last few years mainly for civilian application (e.g. Cadastral plan, telecommunications), but opening new opportunities to quantify the present-day rates of crustal deformation. Here we present the initial results of GEOSAB (Geodetic Estimate of Strain Accumulation over Balkans), an AXA-Research-Fund supported project devoted to the estimation of crustal deformation and the associated seismic hazard of the Balkan region. We processed all the currently available data acquired on these new networks using the precise point positioning strategy of the Gipsy-Oasis software (Bertiger et al. 2010) and the daily ITF2008 transformation parameters (x-files) from JPL. Daily coordinates are obtained in a Eurasia-fix reference frame obtained using the strategy developed by Blewitt et al. (2012). Here we present this new velocity field combined with previously published data sets covering the Balkan Peninsula. This unusually dense picture of the current deformation, in particular in Slovenia and Serbia, enables us to derive a continuous map of the strain rate over the region using the approach of Haines and Holt (1993). We then derive the seismogenic potential of the region combining the geodetic strain rate and the available regional CMT moment tensor solutions. These maps bring new insights on areas of significant strain accumulation over the Balkan Peninsula and are a first step to better assess seismic hazard there.

Application of Geostatistical Methods and Machine Learning for spatio-temporal Earthquake Cluster Analysis

NASA Astrophysics Data System (ADS)

Schaefer, A. M.; Daniell, J. E.; Wenzel, F.

2014-12-01

Earthquake clustering tends to be an increasingly important part of general earthquake research especially in terms of seismic hazard assessment and earthquake forecasting and prediction approaches. The distinct identification and definition of foreshocks, aftershocks, mainshocks and secondary mainshocks is taken into account using a point based spatio-temporal clustering algorithm originating from the field of classic machine learning. This can be further applied for declustering purposes to separate background seismicity from triggered seismicity. The results are interpreted and processed to assemble 3D-(x,y,t) earthquake clustering maps which are based on smoothed seismicity records in space and time. In addition, multi-dimensional Gaussian functions are used to capture clustering parameters for spatial distribution and dominant orientations. Clusters are further processed using methodologies originating from geostatistics, which have been mostly applied and developed in mining projects during the last decades. A 2.5D variogram analysis is applied to identify spatio-temporal homogeneity in terms of earthquake density and energy output. The results are mitigated using Kriging to provide an accurate mapping solution for clustering features. As a case study, seismic data of New Zealand and the United States is used, covering events since the 1950s, from which an earthquake cluster catalogue is assembled for most of the major events, including a detailed analysis of the Landers and Christchurch sequences.

Shallow subsurface structure of the Wasatch fault, Provo segment, Utah, from integrated compressional and shear-wave seismic reflection profiles with implications for fault structure and development

USGS Publications Warehouse

McBride, J.H.; Stephenson, W.J.; Williams, R.A.; Odum, J.K.; Worley, D.M.; South, J.V.; Brinkerhoff, A.R.; Keach, R.W.; Okojie-Ayoro, A. O.

2010-01-01

Integrated vibroseis compressional and experimental hammer-source, shear-wave, seismic reflection profiles across the Provo segment of the Wasatch fault zone in Utah reveal near-surface and shallow bedrock structures caused by geologically recent deformation. Combining information from the seismic surveys, geologic mapping, terrain analysis, and previous seismic first-arrival modeling provides a well-constrained cross section of the upper ~500 m of the subsurface. Faults are mapped from the surface, through shallow, poorly consolidated deltaic sediments, and cutting through a rigid bedrock surface. The new seismic data are used to test hypotheses on changing fault orientation with depth, the number of subsidiary faults within the fault zone and the width of the fault zone, and the utility of integrating separate elastic methods to provide information on a complex structural zone. Although previous surface mapping has indicated only a few faults, the seismic section shows a wider and more complex deformation zone with both synthetic and antithetic normal faults. Our study demonstrates the usefulness of a combined shallow and deeper penetrating geophysical survey, integrated with detailed geologic mapping to constrain subsurface fault structure. Due to the complexity of the fault zone, accurate seismic velocity information is essential and was obtained from a first-break tomography model. The new constraints on fault geometry can be used to refine estimates of vertical versus lateral tectonic movements and to improve seismic hazard assessment along the Wasatch fault through an urban area. We suggest that earthquake-hazard assessments made without seismic reflection imaging may be biased by the previous mapping of too few faults. ?? 2010 Geological Society of America.

Probabilistic seismic hazard assessment of southern part of Ghana

NASA Astrophysics Data System (ADS)

Ahulu, Sylvanus T.; Danuor, Sylvester Kojo; Asiedu, Daniel K.

2018-05-01

This paper presents a seismic hazard map for the southern part of Ghana prepared using the probabilistic approach, and seismic hazard assessment results for six cities. The seismic hazard map was prepared for 10% probability of exceedance for peak ground acceleration in 50 years. The input parameters used for the computations of hazard were obtained using data from a catalogue that was compiled and homogenised to moment magnitude (Mw). The catalogue covered a period of over a century (1615-2009). The hazard assessment is based on the Poisson model for earthquake occurrence, and hence, dependent events were identified and removed from the catalogue. The following attenuation relations were adopted and used in this study—Allen (for south and eastern Australia), Silva et al. (for Central and eastern North America), Campbell and Bozorgnia (for worldwide active-shallow-crust regions) and Chiou and Youngs (for worldwide active-shallow-crust regions). Logic-tree formalism was used to account for possible uncertainties associated with the attenuation relationships. OpenQuake software package was used for the hazard calculation. The highest level of seismic hazard is found in the Accra and Tema seismic zones, with estimated peak ground acceleration close to 0.2 g. The level of the seismic hazard in the southern part of Ghana diminishes with distance away from the Accra/Tema region to a value of 0.05 g at a distance of about 140 km.

United States National Seismic Hazard Maps

USGS Publications Warehouse

Petersen, M.D.; ,

2008-01-01

The U.S. Geological Survey?s maps of earthquake shaking hazards provide information essential to creating and updating the seismic design provisions of building codes and insurance rates used in the United States. Periodic revisions of these maps incorporate the results of new research. Buildings, bridges, highways, and utilities built to meet modern seismic design provisions are better able to withstand earthquakes, not only saving lives but also enabling critical activities to continue with less disruption. These maps can also help people assess the hazard to their homes or places of work and can also inform insurance rates.

Seismic risk assessment of architectural heritages in Gyeongju considering local site effects

NASA Astrophysics Data System (ADS)

Park, H.-J.; Kim, D.-S.; Kim, D.-M.

2013-02-01

A seismic risk assessment is conducted for cultural heritage sites in Gyeongju, the capital of Korea's ancient Silla Kingdom. Gyeongju, home to UNESCO World Heritage sites, contains remarkable artifacts of Korean Buddhist art. An extensive geotechnical survey including a series of in situ tests is presented, providing pertinent soil profiles for site response analyses on thirty cultural heritage sites. After the shear wave velocity profiles and dynamic material properties were obtained, site response analyses were carried out at each historical site and the amplification characteristics, site period, and response spectrum of the site were determined for the earthquake levels of 2400 yr and 1000 yr return periods based on the Korean seismic hazard map. Response spectrum and corresponding site coefficients obtained from site response analyses considering geologic conditions differ significantly from the current Korean seismic code. This study confirms the importance of site-specific ground response analyses considering local geological conditions. Results are given in the form of the spatial distribution of bedrock depth, site period, and site amplification coefficients, which are particularly valuable in the context of a seismic vulnerability study. This study presents the potential amplification of hazard maps and provides primary data on the seismic risk assessment of each cultural heritage.

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

Parra, J.; Collier, H.; Angstman, B.

In low porosity, low permeability zones, natural fractures are the primary source of permeability which affect both production and injection of fluids. The open fractures do not contribute much to porosity, but they provide an increased drainage network to any porosity. An important approach to characterizing the fracture orientation and fracture permeability of reservoir formations is one based upon the effects of such conditions on the propagation of acoustic and seismic waves in the rock. We present the feasibility of using seismic measurement techniques to map the fracture zones between wells spaced 2400 ft at depths of about 1000 ft.more » For this purpose we constructed computer models (which include azimuthal anisotropy) using Lodgepole reservoir parameters to predict seismic signatures recorded at the borehole scale, crosswell scale, and 3 D seismic scale. We have integrated well logs with existing 2D surfaces seismic to produce petrophysical and geological cross sections to determine the reservoir parameters and geometry for the computer models. In particular, the model responses are used to evaluate if surface seismic and crosswell seismic measurements can capture the anisotropy due to vertical fractures. Preliminary results suggested that seismic waves transmitted between two wells will propagate in carbonate fracture reservoirs, and the signal can be received above the noise level at the distance of 2400 ft. In addition, the large velocities contrast between the main fracture zone and the underlying unfractured Boundary Ridge Member, suggested that borehole reflection imaging may be appropriate to map and fracture zone thickness variation and fracture distributions in the reservoir.« less

Near-surface mapping using SH-wave and P-wave seismic land-streamer data acquisition in Illinois, U.S

USGS Publications Warehouse

Pugin, Andre J.M.; Larson, T.H.; Sargent, S.L.; McBride, J.H.; Bexfield, C.E.

2004-01-01

SH-wave and P-wave high-resolution seismic reflection combined with land-streamer technology provide 3D regional maps of geologic formations that can be associated with aquifers and aquitards. Examples for three study areas are considered to demonstrate this. In these areas, reflection profiling detected near-surface faulting and mapped a buried glacial valley and its aquifers in two settings. The resulting seismic data can be used directly to constrain hydrogeologic modeling of shallow aquifers.

Combined interpretation of 3D seismic reflection attributes for geothermal exploration in the Polish Basin using self-organizing maps

NASA Astrophysics Data System (ADS)

Bauer, Klaus; Pussak, Marcin; Stiller, Manfred; Bujakowski, Wieslaw

2014-05-01

Self-organizing maps (SOM) are neural network techniques which can be used for the joint interpretation of multi-disciplinary data sets. In this investigation we apply SOM within a geothermal exploration project using 3D seismic reflection data. The study area is located in the central part of the Polish basin. Several sedimentary target horizons were identified at this location based on fluid flow rate measurements in the geothermal research well Kompina-2. The general objective is a seismic facies analysis and characterization of the major geothermal target reservoir. A 3D seismic reflection experiment with a sparse acquisition geometry was carried out around well Kompina-2. Conventional signal processing (amplitude corrections, filtering, spectral whitening, deconvolution, static corrections, muting) was followed by normal-moveout (NMO) stacking, and, alternatively, by common-reflection-surface (CRS) stacking. Different signal attributes were then derived from the stacked images including root-mean-square (RMS) amplitude, instantaneous frequency and coherency. Furthermore, spectral decomposition attributes were calculated based on the continuous wavelet transform. The resulting attribute maps along major target horizons appear noisy after the NMO stack and clearly structured after the CRS stack. Consequently, the following SOM-based multi-parameter signal attribute analysis was applied only to the CRS images. We applied our SOM work flow, which includes data preparation, unsupervised learning, segmentation of the trained SOM using image processing techniques, and final application of the learned knowledge. For the Lower Jurassic target horizon Ja1 we derived four different clusters with distinct seismic attribute signatures. As the most striking feature, a corridor parallel to a fault system was identified, which is characterized by decreased RMS amplitudes and low frequencies. In our interpretation we assume that this combination of signal properties can be explained by increased fracture porosity and enhanced fluid saturation within this part of the Lower Jurassic sandstone horizon. Hence, we suggest that a future drilling should be carried out within this compartment of the reservoir.

Seismicity and gravimetric studies of Cyrenaica platform and adjacent regions, northeastern Libya

NASA Astrophysics Data System (ADS)

Ben Suleman, abdunnur

2013-04-01

Cyrenaica, located in northeastern Libya, consists of two distinct tectonic provinces; the tectonically unstable northern Cyrenaica and the more stable Cyernaican platform to the south. This study represents detailed investigations that aim to focus on the structure and tectonic setting through a detailed Seismicity and gravity analysis. Seismicity of northeastern Libya is documented back to 262 A.D. when an earthquake destroyed the city of Ceryne. The same area was destroyed by an earthquake in 365 A.D, The city of Al-Maraj was heavily damaged in 1963 by an earthquake measuring 5,3 in the Richter scale. Data collected by the recently established Libyan National Seismograph Network confirms that northeastern Libya is seismically active with most of the activity concentrates on the northern part particularly in the city of Al-Maraj area. Seismic activity is also noticeable in the offshore area. Focal mechanism studies for a number of earthquakes recorded by the Libyan National Seismograph Network suggest that normal faulting is predominant. A gravity data base collected from a variety of sources was compiled to generate a Bouguer gravity anomaly map that represents the basic map used in the overall interpretations, as well as in generating more specialized gravity maps used in the detailed investigations. The Bouguer gravity map demonstrates that the northern inverted basins of Cyrenaica and the coastal plain of Al-Jabal Al-Akhdar show a raped northward increase in gravity values to up to 130 Mgal. In addition a series of steep faults that separates the unstable Al-Jabal Al-Akhdar from the more stable Cyrenaica platform as well as other faults within the platform were well delineated.

Using Research Data to Stimulate Critical Thinking in Undergraduate Geoscience Courses: Examples and Future Directions

NASA Astrophysics Data System (ADS)

Reed, D. L.; Moore, G. F.; Bangs, N. L.; Tobin, H.

2007-12-01

The results of major research initiatives, such as NSF-MARGINS, IODP and its predecessors DSDP and ODP, Ridge 2000, and NOAA's Ocean Explorer and Vents Programs provide a rich library of resources for inquiry-based learning in undergraduate classes in the geosciences. These materials are scalable for use in general education courses for the non-science major to upper division major and graduate courses, which are both content-rich and research-based. Examples of these materials include images and animations drawn from computer presentations at research workshops and audio/video clips from web sites, as well as data repositories, which can be accessed through GeoMapApp, a data exploration and visualization tool developed as part of the Marine Geoscience Data System by researchers at the LDEO (http://www.geomapapp.org/). Past efforts have focused on recreating sea-going research experiences by integrating and repurposing these data in web-based virtual environments to stimulate active student participation in laboratory settings and at a distance over the WWW. Virtual expeditions have been created based on multibeam mapping of the seafloor near the Golden Gate, bathymetric transects of the major ocean basins, subduction zone seismicity and related tsunamis, water column mapping and submersible dives at hydrothermal vents, and ocean drilling of deep-sea sediments to explore climate change. Students also make use of multichannel seismic data provided through the Marine Seismic Data Center of UTIG to study subduction zone processes at convergent plate boundaries. We will present the initial stages of development of a web-based virtual expedition for use in undergraduate classes, based on a recent 3-D seismic survey associated with the NanTroSEIZE program of NSF-MARGINS and IODP to study the properties of the plate boundary fault system in the upper limit of the seismogenic zone off Japan.

Angola Seismicity MAP

NASA Astrophysics Data System (ADS)

Neto, F. A. P.; Franca, G.

2014-12-01

The purpose of this job was to study and document the Angola natural seismicity, establishment of the first database seismic data to facilitate consultation and search for information on seismic activity in the country. The study was conducted based on query reports produced by National Institute of Meteorology and Geophysics (INAMET) 1968 to 2014 with emphasis to the work presented by Moreira (1968), that defined six seismogenic zones from macro seismic data, with highlighting is Zone of Sá da Bandeira (Lubango)-Chibemba-Oncócua-Iona. This is the most important of Angola seismic zone, covering the epicentral Quihita and Iona regions, geologically characterized by transcontinental structure tectono-magmatic activation of the Mesozoic with the installation of a wide variety of intrusive rocks of ultrabasic-alkaline composition, basic and alkaline, kimberlites and carbonatites, strongly marked by intense tectonism, presenting with several faults and fractures (locally called corredor de Lucapa). The earthquake of May 9, 1948 reached intensity VI on the Mercalli-Sieberg scale (MCS) in the locality of Quihita, and seismic active of Iona January 15, 1964, the main shock hit the grade VI-VII. Although not having significant seismicity rate can not be neglected, the other five zone are: Cassongue-Ganda-Massano de Amorim; Lola-Quilengues-Caluquembe; Gago Coutinho-zone; Cuima-Cachingues-Cambândua; The Upper Zambezi zone. We also analyzed technical reports on the seismicity of the middle Kwanza produced by Hidroproekt (GAMEK) region as well as international seismic bulletins of the International Seismological Centre (ISC), United States Geological Survey (USGS), and these data served for instrumental location of the epicenters. All compiled information made possible the creation of the First datbase of seismic data for Angola, preparing the map of seismicity with the reconfirmation of the main seismic zones defined by Moreira (1968) and the identification of a new seismic zone Porto Amboim in the coastal portion of Kwanza basin sedimentary.

A high-resolution ambient seismic noise model for Europe

NASA Astrophysics Data System (ADS)

Kraft, Toni

2014-05-01

In the past several years, geological energy technologies receive growing attention and have been initiated in or close to urban areas. Some of these technologies involve injecting fluids into the subsurface (e.g., oil and gas development, waste disposal, and geothermal energy development) and have been found or suspected to cause small to moderate sized earthquakes. These earthquakes, which may have gone unnoticed in the past when they occurred in remote sparsely populated areas, are now posing a considerable risk for the public acceptance of these technologies in urban areas. The permanent termination of the EGS project in Basel, Switzerland after a number of induced ML~3 (minor) earthquakes in 2006 is one prominent example. It is therefore essential to the future development and success of these geological energy technologies to develop strategies for managing induced seismicity and keeping the size of induced earthquake at a level that is acceptable to all stakeholders. Most guidelines and recommendations on induced seismicity published since the 1970ies conclude that an indispensable component of such a strategy is the establishment of seismic monitoring in an early stage of a project. This is because an appropriate seismic monitoring is the only way to detect and locate induced microearthquakes with sufficient certainty to develop an understanding of the seismic and geomechanical response of the reservoir to the geotechnical operation. In addition, seismic monitoring lays the foundation for the establishment of advanced traffic light systems and is therefore an important confidence building measure towards the local population and authorities. Due to this development an increasing number of seismic monitoring networks are being installed in densely populated areas with strongly heterogeneous, and unfavorable ambient noise conditions. This poses a major challenge on the network design process, which aims to find the sensor geometry that optimizes the measurement precision (i.e. earthquake location), while considering this extremely complex boundary condition. To solve this problem I have developed a high-resolution ambient seismic noise model for Europe. The model is based on land-use data derived from satellite imagery by the EU-project CORINE in a resolution of 100x100m. The the CORINE data consists of several land-use classes, which, besides others, contain: industrial areas, mines, urban fabric, agricultural areas, permanent corps, forests and open spaces. Additionally, open GIS data for highways, and major and minor roads and railway lines were included from the OpenStreetMap project (www.openstreetmap.org). This data was divided into three classes that represent good, intermediate and bad ambient conditions of the corresponding land-use class based on expert judgment. To account for noise propagation away from its source a smoothing operator was applied to individual land-use noise-fields. Finally, the noise-fields were stacked to obtain an European map of ambient noise conditions. A calibration of this map with data of existing seismic stations Europe allowed me to estimate the expected noise level in actual ground motion units for the three ambient noise condition classes of the map. The result is a high-resolution ambient seismic noise map, that allows the network designer to make educated predictions on the expected noise level for arbitrary location in Europe. The ambient noise model was successfully tested in several network optimization projects in Switzerland and surrounding countries and will hopefully be a valuable contribution to improving the data quality of microseismic monitoring networks in Europe.

The 2008 U.S. Geological Survey national seismic hazard models and maps for the central and eastern United States

USGS Publications Warehouse

Petersen, Mark D.; Frankel, Arthur D.; Harmsen, Stephen C.; Mueller, Charles S.; Boyd, Oliver S.; Luco, Nicolas; Wheeler, Russell L.; Rukstales, Kenneth S.; Haller, Kathleen M.

2012-01-01

In this paper, we describe the scientific basis for the source and ground-motion models applied in the 2008 National Seismic Hazard Maps, the development of new products that are used for building design and risk analyses, relationships between the hazard maps and design maps used in building codes, and potential future improvements to the hazard maps.

A Seismic Source Model for Central Europe and Italy

NASA Astrophysics Data System (ADS)

Nyst, M.; Williams, C.; Onur, T.

2006-12-01

We present a seismic source model for Central Europe (Belgium, Germany, Switzerland, and Austria) and Italy, as part of an overall seismic risk and loss modeling project for this region. A separate presentation at this conference discusses the probabilistic seismic hazard and risk assessment (Williams et al., 2006). Where available we adopt regional consensus models and adjusts these to fit our format, otherwise we develop our own model. Our seismic source model covers the whole region under consideration and consists of the following components: 1. A subduction zone environment in Calabria, SE Italy, with interface events between the Eurasian and African plates and intraslab events within the subducting slab. The subduction zone interface is parameterized as a set of dipping area sources that follow the geometry of the surface of the subducting plate, whereas intraslab events are modeled as plane sources at depth; 2. The main normal faults in the upper crust along the Apennines mountain range, in Calabria and Central Italy. Dipping faults and (sub-) vertical faults are parameterized as dipping plane and line sources, respectively; 3. The Upper and Lower Rhine Graben regime that runs from northern Italy into eastern Belgium, parameterized as a combination of dipping plane and line sources, and finally 4. Background seismicity, parameterized as area sources. The fault model is based on slip rates using characteristic recurrence. The modeling of background and subduction zone seismicity is based on a compilation of several national and regional historic seismic catalogs using a Gutenberg-Richter recurrence model. Merging the catalogs encompasses the deletion of double, fake and very old events and the application of a declustering algorithm (Reasenberg, 2000). The resulting catalog contains a little over 6000 events, has an average b-value of -0.9, is complete for moment magnitudes 4.5 and larger, and is used to compute a gridded a-value model (smoothed historical seismicity) for the region. The logic tree weighs various completeness intervals and minimum magnitudes. Using a weighted scheme of European and global ground motion models together with a detailed site classification map for Europe based on Eurocode 8, we generate hazard maps for recurrence periods of 200, 475, 1000 and 2500 yrs.

A landslide susceptibility map of Africa

NASA Astrophysics Data System (ADS)

Broeckx, Jente; Vanmaercke, Matthias; Duchateau, Rica; Poesen, Jean

2017-04-01

Studies on landslide risks and fatalities indicate that landslides are a global threat to humans, infrastructure and the environment, certainly in Africa. Nonetheless our understanding of the spatial patterns of landslides and rockfalls on this continent is very limited. Also in global landslide susceptibility maps, Africa is mostly underrepresented in the inventories used to construct these maps. As a result, predicted landslide susceptibilities remain subject to very large uncertainties. This research aims to produce a first continent-wide landslide susceptibility map for Africa, calibrated with a well-distributed landslide dataset. As a first step, we compiled all available landslide inventories for Africa. This data was supplemented by additional landslide mapping with Google Earth in underrepresented regions. This way, we compiled 60 landslide inventories from the literature (ca. 11000 landslides) and an additional 6500 landslides through mapping in Google Earth (including 1500 rockfalls). Various environmental variables such as slope, lithology, soil characteristics, land use, precipitation and seismic activity, were investigated for their significance in explaining the observed spatial patterns of landslides. To account for potential mapping biases in our dataset, we used Monte Carlo simulations that selected different subsets of mapped landslides, tested the significance of the considered environmental variables and evaluated the performance of the fitted multiple logistic regression model against another subset of mapped landslides. Based on these analyses, we constructed two landslide susceptibility maps for Africa: one for all landslide types and one excluding rockfalls. In both maps, topography, lithology and seismic activity were the most significant variables. The latter factor may be surprising, given the overall limited degree of seismicity in Africa. However, its significance indicates that frequent seismic events may serve as in important preparatory factor for landslides. This finding concurs with several other recent studies. Rainfall explains a significant, but limited part of the observed landslide pattern and becomes insignificant when also rockfalls are considered. This may be explained by the fact that a significant fraction of the mapped rockfalls occurred in the Sahara desert. Overall, both maps perform well in predicting intra-continental patterns of mass movements in Africa and explain about 80% of the observed variance in landslide occurrence. As a result, these maps may be a valuable tool for planning and risk reduction strategies.

Seismicity map tools for earthquake studies

NASA Astrophysics Data System (ADS)

Boucouvalas, Anthony; Kaskebes, Athanasios; Tselikas, Nikos

2014-05-01

We report on the development of new and online set of tools for use within Google Maps, for earthquake research. We demonstrate this server based and online platform (developped with PHP, Javascript, MySQL) with the new tools using a database system with earthquake data. The platform allows us to carry out statistical and deterministic analysis on earthquake data use of Google Maps and plot various seismicity graphs. The tool box has been extended to draw on the map line segments, multiple straight lines horizontally and vertically as well as multiple circles, including geodesic lines. The application is demonstrated using localized seismic data from the geographic region of Greece as well as other global earthquake data. The application also offers regional segmentation (NxN) which allows the studying earthquake clustering, and earthquake cluster shift within the segments in space. The platform offers many filters such for plotting selected magnitude ranges or time periods. The plotting facility allows statistically based plots such as cumulative earthquake magnitude plots and earthquake magnitude histograms, calculation of 'b' etc. What is novel for the platform is the additional deterministic tools. Using the newly developed horizontal and vertical line and circle tools we have studied the spatial distribution trends of many earthquakes and we here show for the first time the link between Fibonacci Numbers and spatiotemporal location of some earthquakes. The new tools are valuable for examining visualizing trends in earthquake research as it allows calculation of statistics as well as deterministic precursors. We plan to show many new results based on our newly developed platform.

Updating the USGS seismic hazard maps for Alaska

USGS Publications Warehouse

Mueller, Charles; Briggs, Richard; Wesson, Robert L.; Petersen, Mark D.

2015-01-01

The U.S. Geological Survey makes probabilistic seismic hazard maps and engineering design maps for building codes, emergency planning, risk management, and many other applications. The methodology considers all known earthquake sources with their associated magnitude and rate distributions. Specific faults can be modeled if slip-rate or recurrence information is available. Otherwise, areal sources are developed from earthquake catalogs or GPS data. Sources are combined with ground-motion estimates to compute the hazard. The current maps for Alaska were developed in 2007, and included modeled sources for the Alaska-Aleutian megathrust, a few crustal faults, and areal seismicity sources. The megathrust was modeled as a segmented dipping plane with segmentation largely derived from the slip patches of past earthquakes. Some megathrust deformation is aseismic, so recurrence was estimated from seismic history rather than plate rates. Crustal faults included the Fairweather-Queen Charlotte system, the Denali–Totschunda system, the Castle Mountain fault, two faults on Kodiak Island, and the Transition fault, with recurrence estimated from geologic data. Areal seismicity sources were developed for Benioff-zone earthquakes and for crustal earthquakes not associated with modeled faults. We review the current state of knowledge in Alaska from a seismic-hazard perspective, in anticipation of future updates of the maps. Updated source models will consider revised seismicity catalogs, new information on crustal faults, new GPS data, and new thinking on megathrust recurrence, segmentation, and geometry. Revised ground-motion models will provide up-to-date shaking estimates for crustal earthquakes and subduction earthquakes in Alaska.

30 CFR 203.86 - What is in a G&G report?

Code of Federal Regulations, 2010 CFR

2010-07-01

... completions, and indicating which sands and fault blocks will be targeted for completion or recompletion. (c... top and base of sand maps showing well and seismic shot point locations; (2) Isopach maps for net sand... description of anticipated hydrocarbon quality (i.e., specific gravity); and (3) The ranges within the...

Paleobathymetric Reconstruction of Ross Sea: seismic data processing and regional reflectors mapping

NASA Astrophysics Data System (ADS)

Olivo, Elisabetta; De Santis, Laura; Wardell, Nigel; Geletti, Riccardo; Busetti, Martina; Sauli, Chiara; Bergamasco, Andrea; Colleoni, Florence; Vanzella, Walter; Sorlien, Christopher; Wilson, Doug; De Conto, Robert; Powell, Ross; Bart, Phil; Luyendyk, Bruce

2017-04-01

PURPOSE: New maps of some major unconformities of the Ross Sea have been reconstructed, by using seismic data grids, combined with the acoustic velocities from previous works, from new and reprocessed seismic profiles. This work is carried out with the support of PNRA and in the frame of the bilateral Italy-USA project GLAISS (Global Sea Level Rise & Antarctic Ice Sheet Stability predictions), funded by the Ministry of Foreign Affairs. Paleobathymetric maps of 30, 14 and 4 million years ago, three 'key moments' for the glacial history of the Antarctic Ice Sheet, coinciding with global climatic changes. The paleobathymetric maps will then be used for numeric simulations focused on the width and thickness of the Ross Sea Ice Sheet. PRELIMINARY RESULTS: The first step was to create TWT maps of three main unconformity (RSU6, RSU4, and RSU2) of Ross Sea, revisiting and updating the ANTOSTRAT maps, through the interpretation of sedimentary bodies and erosional features, used to infer active or old processes along the slope, we identified the main seismic unconformities. We used the HIS Kingdom academic license. The different groups contribution was on the analysis of the Eastern Ross Sea continental slope and rise (OGS), of the Central Basin (KOPRI) of the western and central Ross Sea (Univ. of Santa Barbara and OGS), where new drill sites and seismic profiles were collected after the publication of the ANTOSTRAT maps. Than we joined our interpretation with previous interpretations. We examined previous processing of several seismic lines and all the old acoustic velocity analysis. In addiction we reprocessed some lines in order to have a higher data coverage. Then, combining the TWT maps of the unconformity with the old and new speed data we created new depth maps of the study area. The new depth maps will then be used for reconstructing the paleobathymetry of the Ross Sea by applying backstripping technique.

Determining the Positions of Seismically Active Faults in Platform Regions Based on the Integrated Profile Observations

NASA Astrophysics Data System (ADS)

Levshenko, V. T.; Grigoryan, A. G.

2018-03-01

By the examples of the Roslavl'skii, Grafskii, and Platava-Varvarinskii faults, the possibility is demonstrated of mapping the geological objects by the measurement algorithm that includes successively measuring the spectra of microseisms at the points of the measurement network by movable instruments and statistical accumulation of the ratios of the power spectra of the amplitudes. Based on this technique, the positions of these seismically active faults are determined by the integrated profile observations of the parameters of microseismic and radon fields. The refined positions of the faults can be used in estimating the seismic impacts on the critical objects in the vicinity of these faults.

Hydrogeologic structure underlying a recharge pond delineated with shear-wave seismic reflection and cone penetrometer data

USGS Publications Warehouse

Haines, S.S.; Pidlisecky, Adam; Knight, R.

2009-01-01

With the goal of improving the understanding of the subsurface structure beneath the Harkins Slough recharge pond in Pajaro Valley, California, USA, we have undertaken a multimodal approach to develop a robust velocity model to yield an accurate seismic reflection section. Our shear-wave reflection section helps us identify and map an important and previously unknown flow barrier at depth; it also helps us map other relevant structure within the surficial aquifer. Development of an accurate velocity model is essential for depth conversion and interpretation of the reflection section. We incorporate information provided by shear-wave seismic methods along with cone penetrometer testing and seismic cone penetrometer testing measurements. One velocity model is based on reflected and refracted arrivals and provides reliable velocity estimates for the full depth range of interest when anchored on interface depths determined from cone data and borehole drillers' logs. A second velocity model is based on seismic cone penetrometer testing data that provide higher-resolution ID velocity columns with error estimates within the depth range of the cone penetrometer testing. Comparison of the reflection/refraction model with the seismic cone penetrometer testing model also suggests that the mass of the cone truck can influence velocity with the equivalent effect of approximately one metre of extra overburden stress. Together, these velocity models and the depth-converted reflection section result in a better constrained hydrologic model of the subsurface and illustrate the pivotal role that cone data can provide in the reflection processing workflow. ?? 2009 European Association of Geoscientists & Engineers.

Fault Specific Seismic Hazard Maps as Input to Loss Reserves Calculation for Attica Buildings

NASA Astrophysics Data System (ADS)

Deligiannakis, Georgios; Papanikolaou, Ioannis; Zimbidis, Alexandros; Roberts, Gerald

2014-05-01

Greece is prone to various natural disasters, such as wildfires, floods, landslides and earthquakes, due to the special environmental and geological conditions dominating in tectonic plate boundaries. Seismic is the predominant risk, in terms of damages and casualties in the Greek territory. The historical record of earthquakes in Greece has been published from various researchers, providing useful data in seismic hazard assessment of Greece. However, the completeness of the historical record in Greece, despite being one of the longest worldwide, reaches only 500 years for M ≥ 7.3 and less than 200 years for M ≥ 6.5. Considering that active faults in the area have recurrence intervals of a few hundred to several thousands of years, it is clear that many active faults have not been activated during the completeness period covered by the historical records. New Seismic Hazard Assessment methodologies tend to follow fault specific approaches where seismic sources are geologically constrained active faults, in order to address problems related to the historical records incompleteness, obtain higher spatial resolution and calculate realistic source locality distances, since seismic sources are very accurately located. Fault specific approaches provide quantitative assessments as they measure fault slip rates from geological data, providing a more reliable estimate of seismic hazard. We used a fault specific seismic hazard assessment approach for the region of Attica. The method of seismic hazard mapping from geological fault throw-rate data combined three major factors: Empirical data which combine fault rupture lengths, earthquake magnitudes and coseismic slip relationships. The radiuses of VI, VII, VIII and IX isoseismals on the Modified Mercalli (MM) intensity scale. Attenuation - amplification functions for seismic shaking on bedrock compared to basin filling sediments. We explicitly modeled 22 active faults that could affect the region of Attica, including Athens, using detailed data derived from published papers, neotectonic maps and fieldwork observations. Moreover, we incorporated background seismicity models from the historic record and also the subduction zone earthquakes distribution, for the integration of strong deep earthquakes that could also affect Attica region. We created 4 high spatial resolution seismic hazard maps for the region of Attica, one for each of the intensities VII - X (MM). These maps offer a locality specific shaking recurrence record, which represents the long-term shaking record in a more complete way, since they incorporate several seismic cycles of the active faults that could affect Attica. Each one of these high resolution seismic hazard maps displays both the spatial distribution and the recurrence, over a specific time period, of the relevant intensity. Time - independent probabilities were extracted based on these average recurrence intervals, using the stationary Poisson model P = 1 -e-Λt. The 'Λ' value was provided by the intensities recurrence, as displayed in the seismic hazard maps. However, the insurance contracts usually lack of detailed spatial information and they refer to Postal Codes level, akin to CRESTA zones. To this end, a time-independent probability of shaking at intensities VII - X was calculated for every Postal Code, for a given time period, using the Poisson model. The reserves calculation on buildings portfolio combines the probability of events of specific intensities within the Postal Codes, with the buildings characteristics, such as the building construction type and the insured value. We propose a standard approach for the reserves calculation K(t) for a specific time period: K (t) = x2 ·[x1 ·y1 ·P1(t) + x1 ·y2 ·P2(t) + x1 ·y3 ·P3(t) + x1 ·y4 ·P4(t)] x1 which is a function of the probabilities of occurrence for the seismic intensities VII - X (P1(t) -P4(t)) for the same period, the value of the building x1, the insured value x2 and the characteristics of the building, such as the construction type, age, height and use of property (y1 - y4). Furthermore a stochastic approach is also adopted in order to obtain the relevant reserve value K(t) for the specific time period. This calculation considers a set of simulations from the Poisson random variable and then taking the respective expectations.

Soil amplification maps for estimating earthquake ground motions in the Central US

USGS Publications Warehouse

Bauer, R.A.; Kiefer, J.; Hester, N.

2001-01-01

The State Geologists of the Central United States Earthquake Consortium (CUSEC) are developing maps to assist State and local emergency managers and community officials in evaluating the earthquake hazards for the CUSEC region. The state geological surveys have worked together to produce a series of maps that show seismic shaking potential for eleven 1 X 2 degree (scale 1:250 000 or 1 in. ??? 3.9 miles) quadrangles that cover the high-risk area of the New Madrid Seismic Zone in eight states. Shear wave velocity values for the surficial materials were gathered and used to classify the soils according to their potential to amplify earthquake ground motions. Geologic base maps of surficial materials or 3-D material maps, either existing or produced for this project, were used in conjunction with shear wave velocities to classify the soils for the upper 15-30 m. These maps are available in an electronic form suitable for inclusion in the federal emergency management agency's earthquake loss estimation program (HAZUS). ?? 2001 Elsevier Science B.V. All rights reserved.

Integrated geophysical and geological study of the tectonic framework of the 38th Parallel Lineament in the vicinity of its intersection with the extension of the New Madrid Fault Zone

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

Braile, L.W.; Hinze, W.J.; Keller, G.R.

1978-06-01

Extensive gravity and aeromagnetic surveys have been conducted in critical areas of Kentucky, Illinois, and Indiana centering around the intersection of the 38th Parallel Lineament and the extension of the New Madrid Fault Zone. Available aeromagnetic maps have been digitized and these data have been processed by a suite of computer programs developed for this purpose. Seismic equipment has been prepared for crustal seismic studies and a 150 km long seismic refraction line has been observed along the Wabash River Valley Fault System. Preliminary basement rock and configuration maps have been prepared based on studies of the samples derived frommore » basement drill holes. Interpretation of these data are at a preliminary stage, but studies to this date indicate that the 38th Parallel Lineament features extend as far north as 39/sup 0/N and a subtle northeasterly striking magnetic and gravity anomaly cuts across Indiana from the southwest corner of the state, roughly on strike with the New Madrid Seismic Zone.« less

The Seismotectonic Map of Africa

NASA Astrophysics Data System (ADS)

Meghraoui, Mustapha

2015-04-01

We present the Seismotectonic Map of Africa based on a geological, geophysical and geodetic database including the instrumental seismicity and re-appraisal of large historical events with harmonization and homogenization of earthquake parameters in catalogues. Although the seismotectonic framework and mapping of the African continent is a difficult task, several previous and ongoing projects provide a wealth of data and outstanding results. The database of large and moderate earthquakes in different geological domains includes the coseismic and Quaternary faulting that reveals the complex nature of the active tectonics in Africa. The map also benefits from previous works on local and regional seismotectonic maps that needed to be integrated with the lithospheric and upper mantle structures from tomographic anisotropy and gravity anomaly into a continental framework. The synthesis of earthquake and volcanic studies with the analysis of long-term (late Quaternary) and short-term (last decades and centuries) active deformation observed with geodetic and other approaches presented along with the seismotectonic map serves as a basis for hazard calculations and the reduction of seismic risks. The map may also be very useful in the assessment of seismic hazard and mitigation of earthquake risk for significant infrastructures and their implications in the socio-economic impact in Africa. In addition, the constant population increase and infrastructure growth in the continent that exacerbate the earthquake risk justify the necessity for a continuous updating of the seismotectonic map. The database and related map are prepared in the framework of the IGC Project-601 "Seismotectonics and Seismic Hazards in Africa" of UNESCO-IUGS, funded by the Swedish International Development Agency and UNESCO-Nairobi for a period of 4 years (2011 - 2014), extended to 2016. * Mustapha Meghraoui (Coordinator) EOST - IPG Strasbourg CNRS-UMR 7516 m.meghraoui@unistra.fr corresponding author. Paulina Amponsah (AECG, Accra), Abdelhakim Ayadi (CRAAG, Algiers), Atalay Ayele (Univ. Addis Ababa), Ateba Bekoa (Bueah Univ. Yaounde), Abdunnur Bensuleman (Tripoli Univ.), Damien Delvaux (MRAC-Tervuren); Mohamed El Gabry (NRIAG, Cairo), Rui-Manuel Fernandes (Beira Univ.) ; Vunganai Midzi & Magda Roos (CGS, Pretoria), Youssef Timoulali (Univ. Mohamed V, Rabat). Website: http://eost.u-strasbg.fr/igcp601/index.html

Time-Independent Annual Seismic Rates, Based on Faults and Smoothed Seismicity, Computed for Seismic Hazard Assessment in Italy

NASA Astrophysics Data System (ADS)

Murru, M.; Falcone, G.; Taroni, M.; Console, R.

2017-12-01

In 2015 the Italian Department of Civil Protection, started a project for upgrading the official Italian seismic hazard map (MPS04) inviting the Italian scientific community to participate in a joint effort for its realization. We participated providing spatially variable time-independent (Poisson) long-term annual occurrence rates of seismic events on the entire Italian territory, considering cells of 0.1°x0.1° from M4.5 up to M8.1 for magnitude bin of 0.1 units. Our final model was composed by two different models, merged in one ensemble model, each one with the same weight: the first one was realized by a smoothed seismicity approach, the second one using the seismogenic faults. The spatial smoothed seismicity was obtained using the smoothing method introduced by Frankel (1995) applied to the historical and instrumental seismicity. In this approach we adopted a tapered Gutenberg-Richter relation with a b-value fixed to 1 and a corner magnitude estimated with the bigger events in the catalogs. For each seismogenic fault provided by the Database of the Individual Seismogenic Sources (DISS), we computed the annual rate (for each cells of 0.1°x0.1°) for magnitude bin of 0.1 units, assuming that the seismic moments of the earthquakes generated by each fault are distributed according to the same tapered Gutenberg-Richter relation of the smoothed seismicity model. The annual rate for the final model was determined in the following way: if the cell falls within one of the seismic sources, we merge the respective value of rate determined by the seismic moments of the earthquakes generated by each fault and the value of the smoothed seismicity model with the same weight; if instead the cells fall outside of any seismic source we considered the rate obtained from the spatial smoothed seismicity. Here we present the final results of our study to be used for the new Italian seismic hazard map.

Revised seismic hazard map for the Kyrgyz Republic

NASA Astrophysics Data System (ADS)

Fleming, Kevin; Ullah, Shahid; Parolai, Stefano; Walker, Richard; Pittore, Massimiliano; Free, Matthew; Fourniadis, Yannis; Villiani, Manuela; Sousa, Luis; Ormukov, Cholponbek; Moldobekov, Bolot; Takeuchi, Ko

2017-04-01

As part of a seismic risk study sponsored by the World Bank, a revised seismic hazard map for the Kyrgyz Republic has been produced, using the OpenQuake-engine developed by the Global Earthquake Model Foundation (GEM). In this project, an earthquake catalogue spanning a period from 250 BCE to 2014 was compiled and processed through spatial and temporal declustering tools. The territory of the Kyrgyz Republic was divided into 31 area sources defined based on local seismicity, including a total area covering 200 km from the border. The results are presented in terms of Peak Ground Acceleration (PGA). In addition, macroseismic intensity estimates, making use of recent intensity prediction equations, were also provided, given that this measure is still widely used in Central Asia. In order to accommodate the associated epistemic uncertainty, three ground motion prediction equations were used in a logic tree structure. A set of representative earthquake scenarios were further identified based on historical data and the nature of the considered faults. The resulting hazard map, as expected, follows the country's seismicity, with the highest levels of hazard in the northeast, south and southwest of the country, with an elevated part around the centre. When considering PGA, the hazard is slightly greater for major urban centres than in previous works (e.g., Abdrakhmatov et al., 2003), although the macroseismic intensity estimates are less than previous studies, e.g., Ulomov (1999). For the scenario assessments, the examples that most affect the urban centres assessed are the Issyk Ata fault (in particular for Bishkek), the Chilik and Kemin faults (in particular Balykchy and Karakol), the Ferghana Valley fault system (in particular Osh, Jalah-Abad and Uzgen), the Oinik Djar fault (Naryn) and the central and western Talas-Ferghanafaukt (Talas). Finally, while site effects (in particular, those dependent on the upper-most geological structure) have an obvious effect on the final hazard level, this is still not fully accounted for, even if a nation-wide first order Vs30 model (i.e., from the USGS) is available. Abdrakhmatov, K., Havenith, H.-B., Delvaux, D., Jongsmans, D. and Trefois, P. (2003) Probabilistic PGA and Arias Intensity maps of Kyrgyzstan (Central Asia), Journal of Seismology, 7, 203-220. Ulomov, V.I., The GSHAP Region 7 working group (1999) Seismic hazard of Northern Eurasia, Annali di Geofisica, 42, 1012-1038.

New mapping technologies - mapping and imaging from space

NASA Technical Reports Server (NTRS)

Blom, R. G.

2000-01-01

New and significantly enhanced space based observational capabiities are available which are of potential use to the hazards community. In combination with existing methodologies, these instruments and data can significantly enhance and extend current procedures for seismic zonation and hazards evaluation. This paper provides a brief overview of several of the more useful data sets available.

Key science issues in the central and eastern United States for the next version of the USGS National Seismic Hazard Maps

USGS Publications Warehouse

Peterson, M.D.; Mueller, C.S.

2011-01-01

The USGS National Seismic Hazard Maps are updated about every six years by incorporating newly vetted science on earthquakes and ground motions. The 2008 hazard maps for the central and eastern United States region (CEUS) were updated by using revised New Madrid and Charleston source models, an updated seismicity catalog and an estimate of magnitude uncertainties, a distribution of maximum magnitudes, and several new ground-motion prediction equations. The new models resulted in significant ground-motion changes at 5 Hz and 1 Hz spectral acceleration with 5% damping compared to the 2002 version of the hazard maps. The 2008 maps have now been incorporated into the 2009 NEHRP Recommended Provisions, the 2010 ASCE-7 Standard, and the 2012 International Building Code. The USGS is now planning the next update of the seismic hazard maps, which will be provided to the code committees in December 2013. Science issues that will be considered for introduction into the CEUS maps include: 1) updated recurrence models for New Madrid sources, including new geodetic models and magnitude estimates; 2) new earthquake sources and techniques considered in the 2010 model developed by the nuclear industry; 3) new NGA-East ground-motion models (currently under development); and 4) updated earthquake catalogs. We will hold a regional workshop in late 2011 or early 2012 to discuss these and other issues that will affect the seismic hazard evaluation in the CEUS.

Application of uphole data from petroleum seismic surveys to groundwater investigations, Abu Dhabi (United Arab Emirates)

USGS Publications Warehouse

Woodward, D.; Menges, C.M.

1991-01-01

Velocity data from uphole surveys were used to map the water table and the contact at the base dune sand/top alluvium as part of a joint National Drilling Company-United States Geological Survey Ground Water Research Project in the Emirate of Abu Dhabi. During 1981-1983, a reconnaissance seismic survey was conducted for petroleum exploration in the eastern region of Abu Dhabi. Approximately 2800 kilometers of seismic data, consisting of 92 lines, were acquired in the 2500 km2 concession area near Al Ain. Uphole surveys were conducted about 2 km apart along each seismic line, and were used to calculate weathering corrections required to further process in the seismic data. Approximately 1300 uphole surveys were completed in the concession area between March 1981 and June 1983. Reinterpretation of the velocity profiles derived from the uphole surveys provided data for determining the following subsurface layers, listed in descending order: (1) a surficial, unconsolidated weathering layer with a velocity from 300 to 450 m/s; (2) surficial dune sand, from 750 to 900 m/s; (3) unsaturated, unconsolidated alluvium, from 1000 to 1300 m/s; and (4) saturated, unconsolidated alluvium, from 1900 to 2200 m/s. Two interfaces-the water table and the base dune sand/top alluvium - were identified and mapped from boundaries between these velocity layers. Although the regional water table can fluctuate naturally as much as 3 m per year in this area and the water-table determinations from the uphole data span a 27-month period, an extremely consistent and interpretable water-table map was derived from the uphole data throughout the entire concession area. In the northern part of the area, unconfined groundwater moves northward and northwestward toward the Arabian Gulf; and in the central and southern parts of the area, groundwater moves westward away from the Oman Mountains. In the extreme southern area east of Jabal Hafit, groundwater moves southward into Oman. The map of the base dune sand/top alluvium suggests a buried paleodrainage network trending westward to southwestward away from the Oman Mountains. These paleodrainages, now buried by dune sand, probably contain alluvial fill and are logical targets for groundwater exploration. ?? 1991.

A critical review of seismotectonic setting of the Campanian Plain (Southern Italy) in GIS environment.

NASA Astrophysics Data System (ADS)

Gaudiosi, Germana; Alessio, Giuliana; Luiso, Paola; Nappi, Rosa; Ricciolino, Patrizia

2010-05-01

The Plio-Pleistocene Campanian Plain is a structural depression of the Southern Italy located between the eastern side of the Tyrrhenian Sea and the Southern Apennine chain. It is surrounded to the North, East and South by the Mesozoic carbonate massifs of the Apennine chain and, to the West, by the Tyrrhenian Sea. The graben origin is similar to other peri-Tyrrhenian regions and is related to a stretching and thinning of the continental crust by the counterclockwise rotation of the Italian peninsula and the contemporaneous opening of the Tyrrhenian sea. The consequent subsidence of the Campanian carbonate platform took place along the Tyrrhenian coast during the Plio-Pleistocene with a maximum vertical extent of 5 km. The plain is filled by volcanic and clastic, continental and marine deposits. Voluminous volcanic activity of Roccamonfina, Campi Flegrei, Ischia, Procida and Vesuvio occurred in the Plain during the Quaternary. In the middle of the plain lies the city of Naples, bordered by the two active volcanoes of Campi Flegrei and Vesuvio. It is a very densely inhabited area that is exposed to high potential volcanic risk. The stress field acting in the Campanian area is poorly known. Structural observations on the Pleistocene faults suggest normal to sinistral movements for the NW- SE-trending faults and normal to dextral for the NE-SW-trending structures. These movements are consistent with those of the structures affecting the inner margin of the Southern Apennines. The Campanian Plain is characterized by seismicity of energy lower than the seismic activity of the Southern Apennine chain. The earthquakes mainly occur along the margin of the plain, in the volcanic areas and a minor seismicity spreads out inside the Plain. The aim of this paper is an attempt to identify active, outcropping and buried fault systems of the Campanian plain through the correlation between seismicity and tectonic structures. Seismic, geologic and geomorphologic data have been analysed in GIS environment. In particular, the seismological data used in this study are relative both to the historical and recent seismic activity, collected by the following Catalogues: CPTI04 Catalogue of Parametric Italian Earthquakes, 2004 (217 b.C to 2002); CSI Catalogue of Instrumental Italian Earthquakes (1981-2002); CNT Seismic Bulletin of Istituto Nazionale di Geofisica e Vulcanologia (2003-2008); Data Base of Seismic Laboratory of Osservatorio Vesuviano (Istituto Nazionale di Geofisica e Vulcanologia) (2000-2009); SisCam Catalogue (Seismotectonic Information System of the Campanian Region) (1980-2000). Seismic data were homogenized in an only one Catalogue. The seismicity of Campi Flegrei and Vesuvio volcanoes have not been studied. The Geological Dataset consists of a merge of all outcropping and buried faults extracted from the available geological and structural maps: Geological map of Italy 1:100.000; Geological map of Southern Italy 1:250.000; Neotectonic Map of Italy 1:500.000; Structural Map of Italy 1:500.000. Two main NW-SE and NE-SW active fault systems have been identified from the joined analysis of seismic epicentres and faults. Moreover, tectonic structure without correlated seismic activity and a spread seismicity, apparently not linked with already known structures (buried faults?), have been identified.

Updated Colombian Seismic Hazard Map

NASA Astrophysics Data System (ADS)

Eraso, J.; Arcila, M.; Romero, J.; Dimate, C.; Bermúdez, M. L.; Alvarado, C.

2013-05-01

The Colombian seismic hazard map used by the National Building Code (NSR-98) in effect until 2009 was developed in 1996. Since then, the National Seismological Network of Colombia has improved in both coverage and technology providing fifteen years of additional seismic records. These improvements have allowed a better understanding of the regional geology and tectonics which in addition to the seismic activity in Colombia with destructive effects has motivated the interest and the need to develop a new seismic hazard assessment in this country. Taking advantage of new instrumental information sources such as new broad band stations of the National Seismological Network, new historical seismicity data, standardized global databases availability, and in general, of advances in models and techniques, a new Colombian seismic hazard map was developed. A PSHA model was applied. The use of the PSHA model is because it incorporates the effects of all seismic sources that may affect a particular site solving the uncertainties caused by the parameters and assumptions defined in this kind of studies. First, the seismic sources geometry and a complete and homogeneous seismic catalog were defined; the parameters of seismic rate of each one of the seismic sources occurrence were calculated establishing a national seismotectonic model. Several of attenuation-distance relationships were selected depending on the type of seismicity considered. The seismic hazard was estimated using the CRISIS2007 software created by the Engineering Institute of the Universidad Nacional Autónoma de México -UNAM (National Autonomous University of Mexico). A uniformly spaced grid each 0.1° was used to calculate the peak ground acceleration (PGA) and response spectral values at 0.1, 0.2, 0.3, 0.5, 0.75, 1, 1.5, 2, 2.5 and 3.0 seconds with return periods of 75, 225, 475, 975 and 2475 years. For each site, a uniform hazard spectrum and exceedance rate curves were calculated. With the results, it is possible to determinate environments and scenarios where the seismic hazard is a function of distance and magnitude and also the principal seismic sources that contribute to the seismic hazard at each site (dissagregation). This project was conducted by the Servicio Geológico Colombiano (Colombian Geological Survey) and the Universidad Nacional de Colombia (National University of Colombia), with the collaboration of national and foreign experts and the National System of Prevention and Attention of Disaster (SNPAD). It is important to stand out that this new seismic hazard map was used in the updated national building code (NSR-10). A new process is ongoing in order to improve and present the Seismic Hazard Map in terms of intensity. This require new knowledge in site effects, in both local and regional scales, checking the existing and develop new acceleration to intensity relationships, in order to obtain results more understandable and useful for a wider range of users, not only in the engineering field, but also all the risk assessment and management institutions, research and general community.

40 CFR 146.82 - Required Class VI permit information.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., Class II, or Class V experimental wells, certain maps, cross-sections, tabulations of wells within the.../facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well...

40 CFR 146.82 - Required Class VI permit information.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., Class II, or Class V experimental wells, certain maps, cross-sections, tabulations of wells within the.../facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well...

40 CFR 146.82 - Required Class VI permit information.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., Class II, or Class V experimental wells, certain maps, cross-sections, tabulations of wells within the.../facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well...

40 CFR 146.82 - Required Class VI permit information.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., Class II, or Class V experimental wells, certain maps, cross-sections, tabulations of wells within the.../facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well...

Probabilistic seismic hazard estimates incorporating site effects - An example from Indiana, U.S.A

USGS Publications Warehouse

Hasse, J.S.; Park, C.H.; Nowack, R.L.; Hill, J.R.

2010-01-01

The U.S. Geological Survey (USGS) has published probabilistic earthquake hazard maps for the United States based on current knowledge of past earthquake activity and geological constraints on earthquake potential. These maps for the central and eastern United States assume standard site conditions with Swave velocities of 760 m/s in the top 30 m. For urban and infrastructure planning and long-term budgeting, the public is interested in similar probabilistic seismic hazard maps that take into account near-surface geological materials. We have implemented a probabilistic method for incorporating site effects into the USGS seismic hazard analysis that takes into account the first-order effects of the surface geologic conditions. The thicknesses of sediments, which play a large role in amplification, were derived from a P-wave refraction database with over 13, 000 profiles, and a preliminary geology-based velocity model was constructed from available information on S-wave velocities. An interesting feature of the preliminary hazard maps incorporating site effects is the approximate factor of two increases in the 1-Hz spectral acceleration with 2 percent probability of exceedance in 50 years for parts of the greater Indianapolis metropolitan region and surrounding parts of central Indiana. This effect is primarily due to the relatively thick sequence of sediments infilling ancient bedrock topography that has been deposited since the Pleistocene Epoch. As expected, the Late Pleistocene and Holocene depositional systems of the Wabash and Ohio Rivers produce additional amplification in the southwestern part of Indiana. Ground motions decrease, as would be expected, toward the bedrock units in south-central Indiana, where motions are significantly lower than the values on the USGS maps.

Probabilistic seismic hazard analysis (PSHA) for Ethiopia and the neighboring region

NASA Astrophysics Data System (ADS)

Ayele, Atalay

2017-10-01

Seismic hazard calculation is carried out for the Horn of Africa region (0°-20° N and 30°-50°E) based on the probabilistic seismic hazard analysis (PSHA) method. The earthquakes catalogue data obtained from different sources were compiled, homogenized to Mw magnitude scale and declustered to remove the dependent events as required by Poisson earthquake source model. The seismotectonic map of the study area that avails from recent studies is used for area sources zonation. For assessing the seismic hazard, the study area was divided into small grids of size 0.5° × 0.5°, and the hazard parameters were calculated at the center of each of these grid cells by considering contributions from all seismic sources. Peak Ground Acceleration (PGA) corresponding to 10% and 2% probability of exceedance in 50 years were calculated for all the grid points using generic rock site with Vs = 760 m/s. Obtained values vary from 0.0 to 0.18 g and 0.0-0.35 g for 475 and 2475 return periods, respectively. The corresponding contour maps showing the spatial variation of PGA values for the two return periods are presented here. Uniform hazard response spectrum (UHRS) for 10% and 2% probability of exceedance in 50 years and hazard curves for PGA and 0.2 s spectral acceleration (Sa) all at rock site are developed for the city of Addis Ababa. The hazard map of this study corresponding to the 475 return periods has already been used to update and produce the 3rd generation building code of Ethiopia.

Evaluation of Horizontal Seismic Hazard of Shahrekord, Iran

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

Amiri, G. Ghodrati; Dehkordi, M. Raeisi; Amrei, S. A. Razavian

2008-07-08

This paper presents probabilistic horizontal seismic hazard assessment of Shahrekord, Iran. It displays the probabilistic estimate of Peak Ground Horizontal Acceleration (PGHA) for the return period of 75, 225, 475 and 2475 years. The output of the probabilistic seismic hazard analysis is based on peak ground acceleration (PGA), which is the most common criterion in designing of buildings. A catalogue of seismic events that includes both historical and instrumental events was developed and covers the period from 840 to 2007. The seismic sources that affect the hazard in Shahrekord were identified within the radius of 150 km and the recurrencemore » relationships of these sources were generated. Finally four maps have been prepared to indicate the earthquake hazard of Shahrekord in the form of iso-acceleration contour lines for different hazard levels by using SEISRISK III software.« less

The Sparta Fault, Southern Greece: From segmentation and tectonic geomorphology to seismic hazard mapping and time dependent probabilities

NASA Astrophysics Data System (ADS)

Papanikolaοu, Ioannis D.; Roberts, Gerald P.; Deligiannakis, Georgios; Sakellariou, Athina; Vassilakis, Emmanuel

2013-06-01

The Sparta Fault system is a major structure approximately 64 km long that bounds the eastern flank of the Taygetos Mountain front (2407 m) and shapes the present-day Sparta basin. It was activated in 464 B.C., devastating the city of Sparta. This fault is examined and described in terms of its geometry, segmentation, drainage pattern and post-glacial throw, emphasising how these parameters vary along strike. Qualitative analysis of long profile catchments shows a significant difference in longitudinal convexity between the central and both the south and north parts of the fault system, leading to the conclusion of varying uplift rate along strike. Catchments are sensitive in differential uplift as it is observed by the calculated differences of the steepness index ksn between the outer (ksn < 83) and central parts (121 < ksn < 138) of the Sparta Fault along strike the fault system. Based on fault throw-rates and the bedrock geology a seismic hazard map has been constructed that extracts a locality specific long-term earthquake recurrence record. Based on this map the town of Sparta would experience a destructive event similar to that in 464 B.C. approximately every 1792 ± 458 years. Since no other major earthquake M ~ 7.0 has been generated by this system since 464 B.C., a future event could be imminent. As a result, not only time-independent but also time-dependent probabilities, which incorporate the concept of the seismic cycle, have been calculated for the town of Sparta, showing a considerably higher time-dependent probability of 3.0 ± 1.5% over the next 30 years compared to the time-independent probability of 1.66%. Half of the hanging wall area of the Sparta Fault can experience intensities ≥ IX, but belongs to the lowest category of seismic risk of the national seismic building code. On view of these relatively high calculated probabilities, a reassessment of the building code might be necessary.

The Sparta Fault, Southern Greece: From Segmentation and Tectonic Geomorphology to Seismic Hazard Mapping and Time Dependent Probabilities

NASA Astrophysics Data System (ADS)

Papanikolaou, Ioannis; Roberts, Gerald; Deligiannakis, Georgios; Sakellariou, Athina; Vassilakis, Emmanuel

2013-04-01

The Sparta Fault system is a major structure approximately 64 km long that bounds the eastern flank of the Taygetos Mountain front (2.407 m) and shapes the present-day Sparta basin. It was activated in 464 B.C., devastating the city of Sparta. This fault is examined and described in terms of its geometry, segmentation, drainage pattern and postglacial throw, emphasizing how these parameters vary along strike. Qualitative analysis of long profile catchments shows a significant difference in longitudinal convexity between the central and both the south and north parts of the fault system, leading to the conclusion of varying uplift rate along strike. Catchments are sensitive in differential uplift as it is observed by the calculated differences of the steepness index ksn between the outer (ksn<83) and central parts (121

A Gis Model Application Supporting The Analysis of The Seismic Hazard For The Urban Area of Catania (italy)

NASA Astrophysics Data System (ADS)

Grasso, S.; Maugeri, M.

After the Summit held in Washington on August 20-22 2001 to plan the first World Conference on the mitigation of Natural Hazards, a Group for the analysis of Natural Hazards within the Mediterranean area has been formed. The Group has so far determined the following hazards: (1) Seismic hazard (hazard for historical buildings included); (2) Hazard linked to the quantity and quality of water; (3) Landslide hazard; (4) Volcanic hazard. The analysis of such hazards implies the creation and the management of data banks, which can only be used if the data are properly geo-settled to allow a crossed use of them. The obtained results must be therefore represented on geo-settled maps. The present study is part of a research programme, namely "Detailed Scenarios and Actions for Seismic Prevention of Damage in the Urban Area of Catania", financed by the National Department for the Civil Protection and the National Research Council-National Group for the Defence Against Earthquakes (CNR-GNDT). Nowadays the south-eastern area of Sicily, called the "Iblea" seismic area of Sicily, is considered as one of the most intense seismic zones in Italy, based on the past and current seismic history and on the typology of civil buildings. Safety against earthquake hazards has two as pects: structural safety against potentially destructive dynamic forces and site safety related to geotechnical phenomena such as amplification, land sliding and soil liquefaction. So the correct evaluation of seismic hazard is highly affected by risk factors due to geological nature and geotechnical properties of soils. The effect of local geotechnical conditions on damages suffered by buildings under seismic conditions has been widely recognized, as it is demonstrated by the Manual for Zonation on Seismic Geotechnical Hazards edited by the International Society for Soil Mechanics and Geotechnical Engineering (TC4, 1999). The evaluation of local amplification effects may be carried out by means of either rigorous complex methods of analysis or qualitative procedures. A semi quantitative procedure based on the definition of the geotechnical hazard index has been applied for the zonation of the seismic geotechnical hazard of the city of Catania. In particular this procedure has been applied to define the influence of geotechnical properties of soil in a central area of the city of Catania, where some historical buildings of great importance are sited. It was also performed an investigation based on the inspection of more than one hundred historical ecclesiastical buildings of great importance, located in the city. Then, in order to identify the amplification effects due to the site conditions, a geotechnical survey form was prepared, to allow a semi quantitative evaluation of the seismic geotechnical hazard for all these historical buildings. In addition, to evaluate the foundation soil time -history response, a 1-D dynamic soil model was employed for all these buildings, considering the non linearity of soil behaviour. Using a GIS, a map of the seismic geotechnical hazard, of the liquefaction hazard and a preliminary map of the seismic hazard for the city of Catania have been obtained. From the analysis of obtained results it may be noticed that high hazard zones are mainly clayey sites

On the problem of earthquake correlation in space and time over large distances

NASA Astrophysics Data System (ADS)

Georgoulas, G.; Konstantaras, A.; Maravelakis, E.; Katsifarakis, E.; Stylios, C. D.

2012-04-01

A quick examination of geographical maps with the epicenters of earthquakes marked on them reveals a strong tendency of these points to form compact clusters of irregular shapes and various sizes often traversing with other clusters. According to [Saleur et al. 1996] "earthquakes are correlated in space and time over large distances". This implies that seismic sequences are not formatted randomly but they follow a spatial pattern with consequent triggering of events. Seismic cluster formation is believed to be due to underlying geological natural hazards, which: a) act as the energy storage elements of the phenomenon, and b) tend to form a complex network of numerous interacting faults [Vallianatos and Tzanis, 1998]. Therefore it is imperative to "isolate" meaningful structures (clusters) in order to mine information regarding the underlying mechanism and at a second stage to test the causality effect implied by what is known as the Domino theory [Burgman, 2009]. Ongoing work by Konstantaras et al. 2011 and Katsifarakis et al. 2011 on clustering seismic sequences in the area of the Southern Hellenic Arc and progressively throughout the Greek vicinity and the entire Mediterranean region based on an explicit segmentation of the data based both on their temporal and spatial stamp, following modelling assumptions proposed by Dobrovolsky et al. 1989 and Drakatos et al. 2001, managed to identify geologically validated seismic clusters. These results suggest that that the time component should be included as a dimension during the clustering process as seismic cluster formation is dynamic and the emerging clusters propagate in time. Another issue that has not been investigated yet explicitly is the role of the magnitude of each seismic event. In other words the major seismic event should be treated differently compared to pre or post seismic sequences. Moreover the sometimes irregular and elongated shapes that appear on geophysical maps means that clustering algorithms such as the well known k-means that tend to form "well-shaped" clusters may not suffice for the problem at hand and other families of unsupervised pattern recognition methods might be a better choice. One such algorithm is the DBSCAN algorithm which is based on the notion of density. In this proposed version the density is not estimated solely on the number of seismic events occurring at a specific spatio-temporal area, but also takes into account the size of the seismic event. A second method proposes the use of a modified measure of proximity that will also account for the size of the earthquake along with traditional clustering schemes such as k-means and agglomerative clustering (k-means is seeded with a quite large number for k and the results are fed to the hierarchical algorithm in order to alleviate the memory requirements on one hand and also allow for irregular shapes on the other hand). Preliminary results of seismic cluster formation using these algorithms appear promising as they are in agreement with geophysical observations on distinct seismic regions, such as those of the neighbouring regions in the Ionian sea and that of the southern Hellenic seismic arc; as well as by the location and orientation of the mapped network of underlying natural hazards beneath each clusters vicinity.

3D Modelling of Seismically Active Parts of Underground Faults via Seismic Data Mining

NASA Astrophysics Data System (ADS)

Frantzeskakis, Theofanis; Konstantaras, Anthony

2015-04-01

During the last few years rapid steps have been taken towards drilling for oil in the western Mediterranean sea. Since most of the countries in the region benefit mainly from tourism and considering that the Mediterranean is a closed sea only replenishing its water once every ninety years careful measures are being taken to ensure safe drilling. In that concept this research work attempts to derive a three dimensional model of the seismically active parts of the underlying underground faults in areas of petroleum interest. For that purpose seismic spatio-temporal clustering has been applied to seismic data to identify potential distinct seismic regions in the area of interest. Results have been coalesced with two dimensional maps of underground faults from past surveys and seismic epicentres, having followed careful reallocation processing, have been used to provide information regarding the vertical extent of multiple underground faults in the region of interest. The end product is a three dimensional map of the possible underground location and extent of the seismically active parts of underground faults. Indexing terms: underground faults modelling, seismic data mining, 3D visualisation, active seismic source mapping, seismic hazard evaluation, dangerous phenomena modelling Acknowledgment This research work is supported by the ESPA Operational Programme, Education and Life Long Learning, Students Practical Placement Initiative. References [1] Alves, T.M., Kokinou, E. and Zodiatis, G.: 'A three-step model to assess shoreline and offshore susceptibility to oil spills: The South Aegean (Crete) as an analogue for confined marine basins', Marine Pollution Bulletin, In Press, 2014 [2] Ciappa, A., Costabile, S.: 'Oil spill hazard assessment using a reverse trajectory method for the Egadi marine protected area (Central Mediterranean Sea)', Marine Pollution Bulletin, vol. 84 (1-2), pp. 44-55, 2014 [3] Ganas, A., Karastathis, V., Moshou, A., Valkaniotis, S., Mouzakiotis, E. and Papathanassiou, G.: 'Aftershock relocation and frequency-size distribution, stress inversion and seismotectonic setting of the 7 August 2013 M=5.4 earthquake in Kallidromon Mountain, central Greece', Tectonophysics, vol. 617, pp. 101-113, 2014 [4] Maravelakis, E., Bilalis, N., Mantzorou, I., Konstantaras, A. and Antoniadis, A.: '3D modelling of the oldest olive tree of the world', International Journal Of Computational Engineering Research, vol. 2 (2), pp. 340-347, 2012 [5] Konstantaras, A., Katsifarakis, E, Maravelakis, E, Skounakis, E, Kokkinos, E. and Karapidakis, E.: 'Intelligent spatial-clustering of seismicity in the vicinity of the Hellenic seismic arc', Earth Science Research, vol. 1 (2), pp. 1- 10, 2012 [6] Georgoulas, G., Konstantaras, A., Katsifarakis, E., Stylios, C., Maravelakis, E and Vachtsevanos, G.: 'Seismic-mass" density-based algorithm for spatio-temporal clustering', Expert Systems with Applications, vol. 40 (10), pp. 4183-4189, 2013 [7] Konstantaras, A.: 'Classification of Distinct Seismic Regions and Regional Temporal Modelling of Seismicity in the Vicinity of the Hellenic Seismic Arc', Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of', vol. 99, pp. 1-7, 2013

Evaluation of Seismic Risk of Siberia Territory

NASA Astrophysics Data System (ADS)

Seleznev, V. S.; Soloviev, V. M.; Emanov, A. F.

The outcomes of modern geophysical researches of the Geophysical Survey SB RAS, directed on study of geodynamic situation in large industrial and civil centers on the territory of Siberia with the purpose of an evaluation of seismic risk of territories and prediction of origin of extreme situations of natural and man-caused character, are pre- sented in the paper. First of all it concerns the testing and updating of a geoinformation system developed by Russian Emergency Ministry designed for calculations regarding the seismic hazard and response to distructive earthquakes. The GIS database contains the catalogues of earthquakes and faults, seismic zonation maps, vectorized city maps, information on industrial and housing fund, data on character of building and popula- tion in inhabited places etc. The geoinformation system allows to solve on a basis of probabilistic approaches the following problems: - estimating the earthquake impact, required forces, facilities and supplies for life-support of injured population; - deter- mining the consequences of failures on chemical and explosion-dangerous objects; - optimization problems on assurance technology of conduct of salvage operations. Using this computer program, the maps of earthquake risk have been constructed for several seismically dangerous regions of Siberia. These maps display the data on the probable amount of injured people and relative economic damage from an earthquake, which can occur in various sites of the territory according to the map of seismic zona- tion. The obtained maps have allowed determining places where the detailed seismo- logical observations should be arranged. Along with it on the territory of Siberia the wide-ranging investigations with use of new methods of evaluation of physical state of industrial and civil establishments (buildings and structures, hydroelectric power stations, bridges, dams, etc.), high-performance detailed electromagnetic researches of ground conditions of city territories, roads, runways, etc., studying of seismic con- dition in large industrial and civil centers and others.

Earthquake dynamics. Mapping pressurized volcanic fluids from induced crustal seismic velocity drops.

PubMed

Brenguier, F; Campillo, M; Takeda, T; Aoki, Y; Shapiro, N M; Briand, X; Emoto, K; Miyake, H

2014-07-04

Volcanic eruptions are caused by the release of pressure that has accumulated due to hot volcanic fluids at depth. Here, we show that the extent of the regions affected by pressurized fluids can be imaged through the measurement of their response to transient stress perturbations. We used records of seismic noise from the Japanese Hi-net seismic network to measure the crustal seismic velocity changes below volcanic regions caused by the 2011 moment magnitude (M(w)) 9.0 Tohoku-Oki earthquake. We interpret coseismic crustal seismic velocity reductions as related to the mechanical weakening of the pressurized crust by the dynamic stress associated with the seismic waves. We suggest, therefore, that mapping seismic velocity susceptibility to dynamic stress perturbations can be used for the imaging and characterization of volcanic systems. Copyright © 2014, American Association for the Advancement of Science.

Seismic Hazard Maps for the Maltese Archipelago: Preliminary Results

NASA Astrophysics Data System (ADS)

D'Amico, S.; Panzera, F.; Galea, P. M.

2013-12-01

The Maltese islands form an archipelago of three major islands lying in the Sicily channel at about 140 km south of Sicily and 300 km north of Libya. So far very few investigations have been carried out on seismicity around the Maltese islands and no maps of seismic hazard for the archipelago are available. Assessing the seismic hazard for the region is currently of prime interest for the near-future development of industrial and touristic facilities as well as for urban expansion. A culture of seismic risk awareness has never really been developed in the country, and the public perception is that the islands are relatively safe, and that any earthquake phenomena are mild and infrequent. However, the Archipelago has been struck by several moderate/large events. Although recent constructions of a certain structural and strategic importance have been built according to high engineering standards, the same probably cannot be said for all residential buildings, many higher than 3 storeys, which have mushroomed rapidly in recent years. Such buildings are mostly of unreinforced masonry, with heavy concrete floor slabs, which are known to be highly vulnerable to even moderate ground shaking. We can surely state that in this context planning and design should be based on available national hazard maps. Unfortunately, these kinds of maps are not available for the Maltese islands. In this paper we attempt to compute a first and preliminary probabilistic seismic hazard assessment of the Maltese islands in terms of Peak Ground Acceleration (PGA) and Spectral Acceleration (SA) at different periods. Seismic hazard has been computed using the Esteva-Cornell (1968) approach which is the most widely utilized probabilistic method. It is a zone-dependent approach: seismotectonic and geological data are used coupled with earthquake catalogues to identify seismogenic zones within which earthquakes occur at certain rates. Therefore the earthquake catalogues can be reduced to the activity rate, the b-value of the Gutenberg-Richter relationship and an estimate of the maximum magnitude. In this article we also defined a new seismogenic zones in the central Mediterranean never considered before. In order to determine the ground motion parameters related to a specified probability of exceedance, the above statistical parameters are combined with ground motion prediction equations. Seismic hazard computations have been performed within the island boundaries. The preliminary maps for PGA distribution on rock site obtained for a 10% probability of exceedance shows values ranging between 0.09-0.18 g whereas, SA for 0.2, 04, 1.0 s show values of about 0.21-0.40 g, 0.14-0.24 g and 0.05-0.08 g respectively.

Intelligent inversion method for pre-stack seismic big data based on MapReduce

NASA Astrophysics Data System (ADS)

Yan, Xuesong; Zhu, Zhixin; Wu, Qinghua

2018-01-01

Seismic exploration is a method of oil exploration that uses seismic information; that is, according to the inversion of seismic information, the useful information of the reservoir parameters can be obtained to carry out exploration effectively. Pre-stack data are characterised by a large amount of data, abundant information, and so on, and according to its inversion, the abundant information of the reservoir parameters can be obtained. Owing to the large amount of pre-stack seismic data, existing single-machine environments have not been able to meet the computational needs of the huge amount of data; thus, the development of a method with a high efficiency and the speed to solve the inversion problem of pre-stack seismic data is urgently needed. The optimisation of the elastic parameters by using a genetic algorithm easily falls into a local optimum, which results in a non-obvious inversion effect, especially for the optimisation effect of the density. Therefore, an intelligent optimisation algorithm is proposed in this paper and used for the elastic parameter inversion of pre-stack seismic data. This algorithm improves the population initialisation strategy by using the Gardner formula and the genetic operation of the algorithm, and the improved algorithm obtains better inversion results when carrying out a model test with logging data. All of the elastic parameters obtained by inversion and the logging curve of theoretical model are fitted well, which effectively improves the inversion precision of the density. This algorithm was implemented with a MapReduce model to solve the seismic big data inversion problem. The experimental results show that the parallel model can effectively reduce the running time of the algorithm.

Salton Trough Post-seismic Afterslip, Viscoelastic Response, and Contribution to Regional Hazard

NASA Astrophysics Data System (ADS)

Parker, J. W.; Donnellan, A.; Lyzenga, G. A.

2012-12-01

The El Mayor-Cucapah M7.2 April 4 2010 earthquake in Baja California may have affected accumulated hazard to Southern California cities due to loading of regional faults including the Elsinore, San Jacinto and southern San Andreas, faults which already have over a century of tectonic loading. We examine changes observed via multiple seismic and geodetic techniques, including micro seismicity and proposed seismicity-based indicators of hazard, high-quality fault models, the Plate Boundary Observatory GNSS array (with 174 stations showing post-seismic transients with greater than 1 mm amplitude), and interferometric radar maps from UAVSAR (aircraft) flights, showing a network of aseismic fault slip events at distances up to 60 km from the end of the surface rupture. Finite element modeling is used to compute the expected coseismic motions at GPS stations with general agreement, including coseismic uplift at sites ~200 km north of the rupture. Postseismic response is also compared, with GNSS and also with the CIG software "RELAX." An initial examination of hazard is made comparing micro seismicity-based metrics, fault models, and changes to coulomb stress on nearby faults using the finite element model. Comparison of seismicity with interferograms and historic earthquakes show aseismic slip occurs on fault segments that have had earthquakes in the last 70 years, while other segments show no slip at the surface but do show high triggered seismicity. UAVSAR-based estimates of fault slip can be incorporated into the finite element model to correct Coloumb stress change.

Seismic Tomography.

ERIC Educational Resources Information Center

Anderson, Don L.; Dziewonski, Adam M.

1984-01-01

Describes how seismic tomography is used to analyze the waves produced by earthquakes. The information obtained from the procedure can then be used to map the earth's mantle in three dimensions. The resulting maps are then studied to determine such information as the convective flow that propels the crustal plates. (JN)

Neural network analysis of crosshole tomographic images: The seismic signature of gas hydrate bearing sediments in the Mackenzie Delta (NW Canada)

NASA Astrophysics Data System (ADS)

Bauer, K.; Pratt, R. G.; Haberland, C.; Weber, M.

2008-10-01

Crosshole seismic experiments were conducted to study the in-situ properties of gas hydrate bearing sediments (GHBS) in the Mackenzie Delta (NW Canada). Seismic tomography provided images of P velocity, anisotropy, and attenuation. Self-organizing maps (SOM) are powerful neural network techniques to classify and interpret multi-attribute data sets. The coincident tomographic images are translated to a set of data vectors in order to train a Kohonen layer. The total gradient of the model vectors is determined for the trained SOM and a watershed segmentation algorithm is used to visualize and map the lithological clusters with well-defined seismic signatures. Application to the Mallik data reveals four major litho-types: (1) GHBS, (2) sands, (3) shale/coal interlayering, and (4) silt. The signature of seismic P wave characteristics distinguished for the GHBS (high velocities, strong anisotropy and attenuation) is new and can be used for new exploration strategies to map and quantify gas hydrates.

Mapping Shear-wave Velocity Structures of the "African Anomaly" Along a Northwest to Southeast Arc From New Zealand to the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Frodsham, A. E.; Wen, L.

2006-12-01

A previous study [Wang and Wen, 2006] investigated the geometry and shear velocity structure of the "African Anomaly" along a great circle arc from the East Pacific Rise to the Japan Sea, and concluded the anomaly extends 1300 km above the core-mantle boundary, that the sides of the anomaly slope towards the apex and has velocity deviations of -5% in the base and -2% to -3% in the mid-lower mantle. Wang and Wen [2004] also reported on the very low velocity province that forms the base of the "African Anomaly" and its lateral extent, but the northern edge of the anomaly was poorly constrained because of the nature of the seismic data. In this presentation we focus on the nature of the anomaly in a cross-section of the mantle along a great arc, from New Zealand, to the Mid-Atlantic Ridge off the coast of Newfoundland, centered over the anomaly. In particular, we focus on the northern edge of the "African Anomaly" where a paucity of large, deep focus earthquakes makes seismic arrivals from the northwest difficult to analyze. We map the lateral extent, thickness, and shear velocity structures of the "African Anomaly" on the basis of forward travel time and waveform modeling of direct S, ScS, and SKS waves. Seismic data used in this study were collected from PASSCAL arrays: KAAPVAAL seismic array (operating years 1997-1999), Tanzania seismic array (1994- 1995), Ethiopia/Kenya seismic array (2000-2002), and the Global Seismographic Network (1994-2002). We minimize uncertainty from earthquake mislocation by relocation of the earthquakes using a global tomographic shear wave velocity model and also correct for heterogeneities outside the anomaly. We explore various methods of data processing, such as frequency filtration, low fold stacking, and cross correlation, to best interpret the arrival times of the various seismic phases and constrain the nature of the "African Anomaly" along a northwest to southeast cross-section.

Deaggregation of Probabilistic Ground Motions in the Central and Eastern United States

USGS Publications Warehouse

Harmsen, S.; Perkins, D.; Frankel, A.

1999-01-01

Probabilistic seismic hazard analysis (PSHA) is a technique for estimating the annual rate of exceedance of a specified ground motion at a site due to known and suspected earthquake sources. The relative contributions of the various sources to the total seismic hazard are determined as a function of their occurrence rates and their ground-motion potential. The separation of the exceedance contributions into bins whose base dimensions are magnitude and distance is called deaggregation. We have deaggregated the hazard analyses for the new USGS national probabilistic ground-motion hazard maps (Frankel et al., 1996). For points on a 0.2?? grid in the central and eastern United States (CEUS), we show color maps of the geographical variation of mean and modal magnitudes (M??, M??) and distances (D??, D??) for ground motions having a 2% chance of exceedance in 50 years. These maps are displayed for peak horizontal acceleration and for spectral response accelerations of 0.2, 0.3, and 1.0 sec. We tabulate M??, D??, M??, and D?? for 49 CEUS cities for 0.2- and 1.0-sec response. Thus, these maps and tables are PSHA-derived estimates of the potential earthquakes that dominate seismic hazard at short and intermediate periods in the CEUS. The contribution to hazard of the New Madrid and Charleston sources dominates over much of the CEUS; for 0.2-sec response, over 40% of the area; for 1.0-sec response, over 80% of the area. For 0.2-sec response, D?? ranges from 20 to 200 km, for 1.0 sec, 30 to 600 km. For sites influenced by New Madrid or Charleston, D is less than the distance to these sources, and M?? is less than the characteristic magnitude of these sources, because averaging takes into account the effect of smaller magnitude and closer sources. On the other hand, D?? is directly the distance to New Madrid or Charleston and M?? for 0.2- and 1.0-sec response corresponds to the dominating source over much of the CEUS. For some cities in the North Atlantic states, short-period seismic hazard is apt to be controlled by local seismicity, whereas intermediate period (1.0 sec) hazard is commonly controlled by regional seismicity, such as that of the Charlevoix seismic zone.

High-sensitivity aeromagnetic survey of the US Atlantic continental margin.

USGS Publications Warehouse

Behrendt, John C.; Klitgord, Kim D.

1980-01-01

The US Geological Survey contracted a high-sensitivity, digital aeromagnetic survey that was flown over the US Atlantic continental margin over a period of 15 months between 1974 and 1976. The 185 000 km of profile data have a relative accuracy approaching a few tenths of a nanotesla, which allowed compilation into maps at a scale of 1:250 000, with a contour interval of 2 nT. Automatic data processing using the Werner method allowed calculations of apparent depth to sources of the magnetic anomalies on all of the profiles, assuming a dike or interface as a source. Comparison of the computed depths to magnetic basement with multichannel seismic profiles across the survey area helped to reduce ambiguities in magnetic depth estimates and enabled interpolation of basement structures between seismic profiles. The resulting map showing depth to basement of the Atlantic continental margin is compatible with available multichannel seismic data, and we consider it a reasonable representation of the base of the sedimentary column. -Authors

Seismic hazard in the Istanbul metropolitan area: A preliminary re-evaluation

USGS Publications Warehouse

Kalkan, E.; Gulkan, Polat; Ozturk, N.Y.; Celebi, M.

2008-01-01

In 1999, two destructive earthquakes (M7.4 Kocaeli and M7.2 Duzce) occurred in the north west of Turkey and resulted in major stress-drops on the western segment of the North Anatolian Fault system where it continues under the Marmara Sea. These undersea fault segments were recently explored using bathymetric and reflection surveys. These recent findings helped to reshape the seismotectonic environment of the Marmara basin, which is a perplexing tectonic domain. Based on collected new information, seismic hazard of the Marmara region, particularly Istanbul Metropolitan Area and its vicinity, were re-examined using a probabilistic approach. Two seismic source and alternate recurrence models combined with various indigenous and foreign attenuation relationships were adapted within a logic tree formulation to quantify and project the regional exposure on a set of hazard maps. The hazard maps show the peak horizontal ground acceleration and spectral acceleration at 1.0 s. These acceleration levels were computed for 2 and 10 % probabilities of transcendence in 50 years.

Modeling Poroelastic Wave Propagation in a Real 2-D Complex Geological Structure Obtained via Self-Organizing Maps

NASA Astrophysics Data System (ADS)

Itzá Balam, Reymundo; Iturrarán-Viveros, Ursula; Parra, Jorge O.

2018-03-01

Two main stages of seismic modeling are geological model building and numerical computation of seismic response for the model. The quality of the computed seismic response is partly related to the type of model that is built. Therefore, the model building approaches become as important as seismic forward numerical methods. For this purpose, three petrophysical facies (sands, shales and limestones) are extracted from reflection seismic data and some seismic attributes via the clustering method called Self-Organizing Maps (SOM), which, in this context, serves as a geological model building tool. This model with all its properties is the input to the Optimal Implicit Staggered Finite Difference (OISFD) algorithm to create synthetic seismograms for poroelastic, poroacoustic and elastic media. The results show a good agreement between observed and 2-D synthetic seismograms. This demonstrates that the SOM classification method enables us to extract facies from seismic data and allows us to integrate the lithology at the borehole scale with the 2-D seismic data.

Applications of the seismic hazard model of Italy: from a new building code to the L'Aquila trial against seismologists

NASA Astrophysics Data System (ADS)

Meletti, C.

2013-05-01

In 2003, a large national project fur updating the seismic hazard map and the seismic zoning in Italy started, according to the rules fixed by an Ordinance by Italian Prime Minister. New input elements for probabilistic seismic hazard assessment were compiled: the earthquake catalogue, the seismogenic zonation, the catalogue completeness, a set of new attenuation relationships. The map of expected PGA on rock soil condition with 10% probability of exceedance is the new reference seismic hazard map for Italy (http://zonesismiche.mi.ingv.it). In the following, further 9 probabilities of exceedance and the uniform hazard spectra up to 2 seconds together with the disaggregation of the PGA was also released. A comprehensive seismic hazard model that fully describes the seismic hazard in Italy was then available, accessible by a webGis application (http://esse1-gis.mi.ingv.it/en.php). The detailed information make possible to change the approach for evaluating the proper seismic action for designing: from a zone-dependent approach (in Italy there were 4 seismic zones, each one with a single design spectrum) to a site-dependent approach: the design spectrum is now defined at each site of a grid of about 11000 points covering the whole national territory. The new building code becomes mandatory only after the 6 April 2009 L'Aquila earthquake, the first strong event in Italy after the release of the seismic hazard map. The large number of recordings and the values of the experienced accelerations suggested the comparisons between the recorded spectra and spectra defined in the seismic codes Even if such comparisons could be robust only after several consecutive 50-year periods of observation and in a probabilistic approach it is not a single observation that can validate or not the hazard estimate, some of the comparisons that can be undertaken between the observed ground motions and the hazard model used for the seismic code have been performed and have shown that the assumptions and modeling choices made in the Italian hazard study are in line with the observations, by considering different return period, the soil condition at the recording stations and the uncertainties of the model. A further application of Italian seismic hazard model is in the identification of buildings and factories struck by the 2012 Emilia (Italy) earthquakes to be investigated in order to determine if they were still safe or not. The law states that no safety check is needed if the construction experienced a shaking greater than 70% of the design acceleration expected at the site, without abandoning the elastic behavior. The ground motion values are evaluated from the shakemaps available (http://shakemap.rm.ingv.it) and the design accelerations derived from the Building Code, which is based on the reference Italian seismic hazard model. Finally, the national seismic hazard model was one the most debated element during the trial in L'Aquila against the seismologists, experts of Civil Protection Department, sentenced to six years in prison on charges of manslaughter, because, according to the judge, they underestimated the risk in the region, giving a wrong message to the people, before the strong 2009 L'Aquila earthquake.

A global earthquake discrimination scheme to optimize ground-motion prediction equation selection

USGS Publications Warehouse

Garcia, Daniel; Wald, David J.; Hearne, Michael

2012-01-01

We present a new automatic earthquake discrimination procedure to determine in near-real time the tectonic regime and seismotectonic domain of an earthquake, its most likely source type, and the corresponding ground-motion prediction equation (GMPE) class to be used in the U.S. Geological Survey (USGS) Global ShakeMap system. This method makes use of the Flinn–Engdahl regionalization scheme, seismotectonic information (plate boundaries, global geology, seismicity catalogs, and regional and local studies), and the source parameters available from the USGS National Earthquake Information Center in the minutes following an earthquake to give the best estimation of the setting and mechanism of the event. Depending on the tectonic setting, additional criteria based on hypocentral depth, style of faulting, and regional seismicity may be applied. For subduction zones, these criteria include the use of focal mechanism information and detailed interface models to discriminate among outer-rise, upper-plate, interface, and intraslab seismicity. The scheme is validated against a large database of recent historical earthquakes. Though developed to assess GMPE selection in Global ShakeMap operations, we anticipate a variety of uses for this strategy, from real-time processing systems to any analysis involving tectonic classification of sources from seismic catalogs.

An integrated geophysical and geological study of the tectonic framework of the 38th Parallel Lineament in the vicinity of its intersection with the extension of the New Madrid Fault Zone. Geotechnical report

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

Braile, L.W.; Hinze, J.H.; Keller, G.R.

1978-09-01

Extensive gravity and aeromagnetic surveys have been conducted in critical areas of Kentucky, Illinois, and Indiana centering around the intersection of the 38th Parallel Lineament and the extension of the New Madrid Fault Zone. Available aeromagnetic maps have been digitized and these data have been processed by a suite of computer programs developed for this purpose. Seismic equipment has been prepared for crustal seismic studies and a 150 km long seismic refraction line has been observed along the Wabash River Valley Fault System. Preliminary basement rock and configuration maps have been prepared based on studies of the samples derived frommore » basement drill holes. Interpretation of these data are only at a preliminary stage, but studies to this date indicate that the 38th Parallel Lineament features extend as far north as 39 degrees N and a subtle northeasterly-striking magnetic and gravity anomaly cuts across Indiana from the southwest corner of the state, roughly on strike with the New Madrid Seismic Zone.« less

Geodynamic Evolution of Northeastern Tunisia During the Maastrichtian-Paleocene Time: Insights from Integrated Seismic Stratigraphic Analysis

NASA Astrophysics Data System (ADS)

Abidi, Oussama; Inoubli, Mohamed Hédi; Sebei, Kawthar; Amiri, Adnen; Boussiga, Haifa; Nasr, Imen Hamdi; Salem, Abdelhamid Ben; Elabed, Mahmoud

2017-05-01

The Maastrichtian-Paleocene El Haria formation was studied and defined in Tunisia on the basis of outcrops and borehole data; few studies were interested in its three-dimensional extent. In this paper, the El Haria formation is reviewed in the context of a tectono-stratigraphic interval using an integrated seismic stratigraphic analysis based on borehole lithology logs, electrical well logging, well shots, vertical seismic profiles and post-stack surface data. Seismic analysis benefits from appropriate calibration with borehole data, conventional interpretation, velocity mapping, seismic attributes and post-stack model-based inversion. The applied methodology proved to be powerful for charactering the marly Maastrichtian-Paleocene interval of the El Haria formation. Migrated seismic sections together with borehole measurements are used to detail the three-dimensional changes in thickness, facies and depositional environment in the Cap Bon and Gulf of Hammamet regions during the Maastrichtian-Paleocene time. Furthermore, dating based on their microfossil content divulges local and multiple internal hiatuses within the El Haria formation which are related to the geodynamic evolution of the depositional floor since the Campanian stage. Interpreted seismic sections display concordance, unconformities, pinchouts, sedimentary gaps, incised valleys and syn-sedimentary normal faulting. Based on the seismic reflection geometry and terminations, seven sequences are delineated. These sequences are related to base-level changes as the combination of depositional floor paleo-topography, tectonic forces, subsidence and the developed accommodation space. These factors controlled the occurrence of the various parts of the Maastrichtian-Paleocene interval. Detailed examinations of these deposits together with the analysis of the structural deformation at different time periods allowed us to obtain a better understanding of the sediment architecture in depth and the delineation of the geodynamic evolution of the region.

Risk-targeted maps for Romania

NASA Astrophysics Data System (ADS)

Vacareanu, Radu; Pavel, Florin; Craciun, Ionut; Coliba, Veronica; Arion, Cristian; Aldea, Alexandru; Neagu, Cristian

2018-03-01

Romania has one of the highest seismic hazard levels in Europe. The seismic hazard is due to a combination of local crustal seismic sources, situated mainly in the western part of the country and the Vrancea intermediate-depth seismic source, which can be found at the bend of the Carpathian Mountains. Recent seismic hazard studies have shown that there are consistent differences between the slopes of the seismic hazard curves for sites situated in the fore-arc and back-arc of the Carpathian Mountains. Consequently, in this study we extend this finding to the evaluation of the probability of collapse of buildings and finally to the development of uniform risk-targeted maps. The main advantage of uniform risk approach is that the target probability of collapse will be uniform throughout the country. Finally, the results obtained are discussed in the light of a recent study with the same focus performed at European level using the hazard data from SHARE project. The analyses performed in this study have pointed out to a dominant influence of the quantile of peak ground acceleration used for anchoring the fragility function. This parameter basically alters the shape of the risk-targeted maps shifting the areas which have higher collapse probabilities from eastern Romania to western Romania, as its exceedance probability increases. Consequently, a uniform procedure for deriving risk-targeted maps appears as more than necessary.

A combined approach based on MAF analysis and AHP method to fault detection mapping: A case study from a gas field, southwest of Iran

NASA Astrophysics Data System (ADS)

Shakiba, Sima; Asghari, Omid; Khah, Nasser Keshavarz Faraj

2018-01-01

A combined geostatitical methodology based on Min/Max Auto-correlation Factor (MAF) analysis and Analytical Hierarchy Process (AHP) is presented to generate a suitable Fault Detection Map (FDM) through seismic attributes. Five seismic attributes derived from a 2D time slice obtained from data related to a gas field located in southwest of Iran are used including instantaneous amplitude, similarity, energy, frequency, and Fault Enhancement Filter (FEF). The MAF analysis is implemented to reduce dimension of input variables, and then AHP method is applied on three obtained de-correlated MAF factors as evidential layer. Three Decision Makers (DMs) are used to construct PCMs for determining weights of selected evidential layer. Finally, weights obtained by AHP were multiplied in normalized valued of each alternative (MAF layers) and the concluded weighted layers were integrated in order to prepare final FDM. Results proved that applying algorithm proposed in this study generate a map more acceptable than the each individual attribute and sharpen the non-surface discontinuities as well as enhancing continuity of detected faults.

A bayesian approach for determining velocity and uncertainty estimates from seismic cone penetrometer testing or vertical seismic profiling data

USGS Publications Warehouse

Pidlisecky, Adam; Haines, S.S.

2011-01-01

Conventional processing methods for seismic cone penetrometer data present several shortcomings, most notably the absence of a robust velocity model uncertainty estimate. We propose a new seismic cone penetrometer testing (SCPT) data-processing approach that employs Bayesian methods to map measured data errors into quantitative estimates of model uncertainty. We first calculate travel-time differences for all permutations of seismic trace pairs. That is, we cross-correlate each trace at each measurement location with every trace at every other measurement location to determine travel-time differences that are not biased by the choice of any particular reference trace and to thoroughly characterize data error. We calculate a forward operator that accounts for the different ray paths for each measurement location, including refraction at layer boundaries. We then use a Bayesian inversion scheme to obtain the most likely slowness (the reciprocal of velocity) and a distribution of probable slowness values for each model layer. The result is a velocity model that is based on correct ray paths, with uncertainty bounds that are based on the data error. ?? NRC Research Press 2011.

Multiple field-based methods to assess the potential impacts of seismic surveys on scallops.

PubMed

Przeslawski, Rachel; Huang, Zhi; Anderson, Jade; Carroll, Andrew G; Edmunds, Matthew; Hurt, Lynton; Williams, Stefan

2018-04-01

Marine seismic surveys are an important tool to map geology beneath the seafloor and manage petroleum resources, but they are also a source of underwater noise pollution. A mass mortality of scallops in the Bass Strait, Australia occurred a few months after a marine seismic survey in 2010, and fishing groups were concerned about the potential relationship between the two events. The current study used three field-based methods to investigate the potential impact of marine seismic surveys on scallops in the region: 1) dredging and 2) deployment of Autonomous Underwater Vehicles (AUVs) were undertaken to examine the potential response of two species of scallops (Pecten fumatus, Mimachlamys asperrima) before, two months after, and ten months after a 2015 marine seismic survey; and 3) MODIS satellite data revealed patterns of sea surface temperatures from 2006-2016. Results from the dredging and AUV components show no evidence of scallop mortality attributable to the seismic survey, although sub-lethal effects cannot be excluded. The remote sensing revealed a pronounced thermal spike in the eastern Bass Strait between February and May 2010, overlapping the scallop beds that suffered extensive mortality and coinciding almost exactly with dates of operation for the 2010 seismic survey. The acquisition of in situ data coupled with consideration of commercial seismic arrays meant that results were ecologically realistic, while the paired field-based components (dredging, AUV imagery) provided a failsafe against challenges associated with working wholly in the field. This study expands our knowledge of the potential environmental impacts of marine seismic survey and will inform future applications for marine seismic surveys, as well as the assessment of such applications by regulatory authorities. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Slope Stability Analysis In Seismic Areas Of The Northern Apennines (Italy)

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

Lo Presti, D.; Fontana, T.; Marchetti, D.

2008-07-08

Several research works have been published on the slope stability in the northern Tuscany (central Italy) and particularly in the seismic areas of Garfagnana and Lunigiana (Lucca and Massa-Carrara districts), aimed at analysing the slope stability under static and dynamic conditions and mapping the landslide hazard. In addition, in situ and laboratory investigations are available for the study area, thanks to the activities undertaken by the Tuscany Seismic Survey. Based on such a huge information the co-seismic stability of few ideal slope profiles have been analysed by means of Limit equilibrium method LEM - (pseudo-static) and Newmark sliding block analysismore » (pseudo-dynamic). The analysis--results gave indications about the most appropriate seismic coefficient to be used in pseudo-static analysis after establishing allowable permanent displacement. Such indications are commented in the light of the Italian and European prescriptions for seismic stability analysis with pseudo-static approach. The stability conditions, obtained from the previous analyses, could be used to define microzonation criteria for the study area.« less

Spatial and temporal seismic velocity changes on Kyushu Island during the 2016 Kumamoto earthquake

PubMed Central

Nimiya, Hiro; Ikeda, Tatsunori; Tsuji, Takeshi

2017-01-01

Monitoring of earthquake faults and volcanoes contributes to our understanding of their dynamic mechanisms and to our ability to predict future earthquakes and volcanic activity. We report here on spatial and temporal variations of seismic velocity around the seismogenic fault of the 2016 Kumamoto earthquake [moment magnitude (Mw) 7.0] based on ambient seismic noise. Seismic velocity near the rupture faults and Aso volcano decreased during the earthquake. The velocity reduction near the faults may have been due to formation damage, a change in stress state, and an increase in pore pressure. Further, we mapped the post-earthquake fault-healing process. The largest seismic velocity reduction observed at Aso volcano during the earthquake was likely caused by pressurized volcanic fluids, and the large increase in seismic velocity at the volcano’s magma body observed ~3 months after the earthquake may have been a response to depressurization caused by the eruption. This study demonstrates the usefulness of continuous monitoring of faults and volcanoes. PMID:29202026

Semi-automatic mapping for identifying complex geobodies in seismic images

NASA Astrophysics Data System (ADS)

Domínguez-C, Raymundo; Romero-Salcedo, Manuel; Velasquillo-Martínez, Luis G.; Shemeretov, Leonid

2017-03-01

Seismic images are composed of positive and negative seismic wave traces with different amplitudes (Robein 2010 Seismic Imaging: A Review of the Techniques, their Principles, Merits and Limitations (Houten: EAGE)). The association of these amplitudes together with a color palette forms complex visual patterns. The color intensity of such patterns is directly related to impedance contrasts: the higher the contrast, the higher the color intensity. Generally speaking, low impedance contrasts are depicted with low tone colors, creating zones with different patterns whose features are not evident for a 3D automated mapping option available on commercial software. In this work, a workflow for a semi-automatic mapping of seismic images focused on those areas with low-intensity colored zones that may be associated with geobodies of petroleum interest is proposed. The CIE L*A*B* color space was used to perform the seismic image processing, which helped find small but significant differences between pixel tones. This process generated binary masks that bound color regions to low-intensity colors. The three-dimensional-mask projection allowed the construction of 3D structures for such zones (geobodies). The proposed method was applied to a set of digital images from a seismic cube and tested on four representative study cases. The obtained results are encouraging because interesting geobodies are obtained with a minimum of information.

Evaluation of seismic hazard at the northwestern part of Egypt

NASA Astrophysics Data System (ADS)

Ezzelarab, M.; Shokry, M. M. F.; Mohamed, A. M. E.; Helal, A. M. A.; Mohamed, Abuoelela A.; El-Hadidy, M. S.

2016-01-01

The objective of this study is to evaluate the seismic hazard at the northwestern Egypt using the probabilistic seismic hazard assessment approach. The Probabilistic approach was carried out based on a recent data set to take into account the historic seismicity and updated instrumental seismicity. A homogenous earthquake catalogue was compiled and a proposed seismic sources model was presented. The doubly-truncated exponential model was adopted for calculations of the recurrence parameters. Ground-motion prediction equations that recently recommended by experts and developed based upon earthquake data obtained from tectonic environments similar to those in and around the studied area were weighted and used for assessment of seismic hazard in the frame of logic tree approach. Considering a grid of 0.2° × 0.2° covering the study area, seismic hazard curves for every node were calculated. Hazard maps at bedrock conditions were produced for peak ground acceleration, in addition to six spectral periods (0.1, 0.2, 0.3, 1.0, 2.0 and 3.0 s) for return periods of 72, 475 and 2475 years. The unified hazard spectra of two selected rock sites at Alexandria and Mersa Matruh Cities were provided. Finally, the hazard curves were de-aggregated to determine the sources that contribute most of hazard level of 10% probability of exceedance in 50 years for the mentioned selected sites.

Microzonation of seismic risk in a low-rise Latin American city based on the macroseismic evaluation of the vulnerability of residential buildings: Colima city, México

NASA Astrophysics Data System (ADS)

Zobin, V. M.; Cruz-Bravo, A. A.; Ventura-Ramírez, F.

2010-06-01

A macroseismic methodology of seismic risk microzonation in a low-rise city based on the vulnerability of residential buildings is proposed and applied to Colima city, Mexico. The seismic risk microzonation for Colima consists of two elements: the mapping of residential blocks according to their vulnerability level and the calculation of an expert-opinion based damage probability matrix (DPM) for a given level of earthquake intensity and a given type of residential block. A specified exposure time to the seismic risk for this zonation is equal to the interval between two destructive earthquakes. The damage probability matrices were calculated for three types of urban buildings and five types of residential blocks in Colima. It was shown that only 9% of 1409 residential blocks are able to resist to the Modify Mercalli (MM) intensity VII and VIII earthquakes without significant damage. The proposed DPM-2007 is in good accordance with the experimental damage curves based on the macroseismic evaluation of 3332 residential buildings in Colima that was carried out after the 21 January 2003 intensity MM VII earthquake. This methodology and the calculated PDM-2007 curves may be applied also to seismic risk microzonation for many low-rise cities in Latin America, Asia, and Africa.

Adaptive proxy map server for efficient vector spatial data rendering

NASA Astrophysics Data System (ADS)

Sayar, Ahmet

2013-01-01

The rapid transmission of vector map data over the Internet is becoming a bottleneck of spatial data delivery and visualization in web-based environment because of increasing data amount and limited network bandwidth. In order to improve both the transmission and rendering performances of vector spatial data over the Internet, we propose a proxy map server enabling parallel vector data fetching as well as caching to improve the performance of web-based map servers in a dynamic environment. Proxy map server is placed seamlessly anywhere between the client and the final services, intercepting users' requests. It employs an efficient parallelization technique based on spatial proximity and data density in case distributed replica exists for the same spatial data. The effectiveness of the proposed technique is proved at the end of the article by the application of creating map images enriched with earthquake seismic data records.

Scenarios for local seismic effects of Tulcea (Romania) crustal earthquakes, preliminary approach for the seismic microzoning of Tulcea city

NASA Astrophysics Data System (ADS)

Florin Bǎlan, Å.žTefan; Apostol, Bogdan; Chitea, F.; Anghelache, Mirela Adriana; Cioflan, Carmen O.; Serban, A.

2010-05-01

The discussed area, Tulcea, is delimitated by the Scythian Platform in the North and Moessian Platform in the South, not far from the Black Sea coast. Natural disasters in the city could occur due to Vrancea intermediate-depth (subcrustal) earthquakes and crustal earthquakes caused by active faults. In the last 30 years three important seismic events affected the region of interest with the following recorded magnitudes: MW = 5.1 (13.11.1981) followed in the same day by 6 aftershocks (at depth 0-9 km) with MW = 2.9-3.3; MW = 5 (27.04.1986) and MW = 4.9 (3.10.2004) followed by two aftershocks. Information about the seismic zone of Tulcea is from three seismic catalogues made by Florinescu (1958), Constantinescu and Mârza (1980) and ROMPLUS (2008), but for urban planning of Tulcea city is very important to be better understood the effect of active faults (Măcin-Cerna, Tulcea-Isaccea, Peceneaga-Camena etc) located in the Pre-Dobrogean Depression (our interest area) in the two parts of the city. Regarding the effects of Vrancea subcrustal earthquakes, as the Tulcea city is situated relatively at a large distance from the epicenters, there is necessary to improve the actual method of microzonation based on Medvedev's method. In order to discuss the local seismic site effects we have considered two scenarios, which take into account the characteristics of the seismogenic area. The first one considers the city exposed to a seismic event with magnitude Mw = 5.1 from Sf. Gheorghe fault and the second one considers the city exposed to an earthquake from the EV zone (superficial). The earthquake epicentres are located in very active seismic areas. The absolute response spectra at the bedrock and at surface will be calculated and the characteristic transfer functions, as well. Nonlinear effects induced by significant deformations need a certain method - linear equivalent - for a multistratified zone, as we considered for the Tulcea superficial area. Therefore, important nonlinear variations of shear modulus and damping function with state of strain during the earthquakes are expected in superficial soil deposits. Also, the epicenter distributions, the isobats map and 3D image of focal distribution surface will be presented together with the focal mechanisms of the most significant earthquakes which had affected the zone. All these give us a very complete image of the crustal seismic hazard of the Tulcea zone. This study proposes itself to take in consideration only the local effects of the crustal seismic hazard from Tulcea zone, like a preliminary step for the seismic microzoning of Tulcea city. The latter is a broader research which implies the interdisciplinary work between specialists from different fields of research. Finally, by comparing the seismic microzoning map with the vulnerability distribution mapping for each building type and damage distribution maps, the general aspect of the real earthquake effects over the city is figured out. Acknowledgements: The research was performed with financial support from the CNMP within 31036/ 2007 scientific project.

St. Louis area earthquake hazards mapping project; seismic and liquefaction hazard maps

USGS Publications Warehouse

Cramer, Chris H.; Bauer, Robert A.; Chung, Jae-won; Rogers, David; Pierce, Larry; Voigt, Vicki; Mitchell, Brad; Gaunt, David; Williams, Robert; Hoffman, David; Hempen, Gregory L.; Steckel, Phyllis; Boyd, Oliver; Watkins, Connor M.; Tucker, Kathleen; McCallister, Natasha

2016-01-01

We present probabilistic and deterministic seismic and liquefaction hazard maps for the densely populated St. Louis metropolitan area that account for the expected effects of surficial geology on earthquake ground shaking. Hazard calculations were based on a map grid of 0.005°, or about every 500 m, and are thus higher in resolution than any earlier studies. To estimate ground motions at the surface of the model (e.g., site amplification), we used a new detailed near‐surface shear‐wave velocity model in a 1D equivalent‐linear response analysis. When compared with the 2014 U.S. Geological Survey (USGS) National Seismic Hazard Model, which uses a uniform firm‐rock‐site condition, the new probabilistic seismic‐hazard estimates document much more variability. Hazard levels for upland sites (consisting of bedrock and weathered bedrock overlain by loess‐covered till and drift deposits), show up to twice the ground‐motion values for peak ground acceleration (PGA), and similar ground‐motion values for 1.0 s spectral acceleration (SA). Probabilistic ground‐motion levels for lowland alluvial floodplain sites (generally the 20–40‐m‐thick modern Mississippi and Missouri River floodplain deposits overlying bedrock) exhibit up to twice the ground‐motion levels for PGA, and up to three times the ground‐motion levels for 1.0 s SA. Liquefaction probability curves were developed from available standard penetration test data assuming typical lowland and upland water table levels. A simplified liquefaction hazard map was created from the 5%‐in‐50‐year probabilistic ground‐shaking model. The liquefaction hazard ranges from low (60% of area expected to liquefy) in the lowlands. Because many transportation routes, power and gas transmission lines, and population centers exist in or on the highly susceptible lowland alluvium, these areas in the St. Louis region are at significant potential risk from seismically induced liquefaction and associated ground deformation

CyberShake: Running Seismic Hazard Workflows on Distributed HPC Resources

NASA Astrophysics Data System (ADS)

Callaghan, S.; Maechling, P. J.; Graves, R. W.; Gill, D.; Olsen, K. B.; Milner, K. R.; Yu, J.; Jordan, T. H.

2013-12-01

As part of its program of earthquake system science research, the Southern California Earthquake Center (SCEC) has developed a simulation platform, CyberShake, to perform physics-based probabilistic seismic hazard analysis (PSHA) using 3D deterministic wave propagation simulations. CyberShake performs PSHA by simulating a tensor-valued wavefield of Strain Green Tensors, and then using seismic reciprocity to calculate synthetic seismograms for about 415,000 events per site of interest. These seismograms are processed to compute ground motion intensity measures, which are then combined with probabilities from an earthquake rupture forecast to produce a site-specific hazard curve. Seismic hazard curves for hundreds of sites in a region can be used to calculate a seismic hazard map, representing the seismic hazard for a region. We present a recently completed PHSA study in which we calculated four CyberShake seismic hazard maps for the Southern California area to compare how CyberShake hazard results are affected by different SGT computational codes (AWP-ODC and AWP-RWG) and different community velocity models (Community Velocity Model - SCEC (CVM-S4) v11.11 and Community Velocity Model - Harvard (CVM-H) v11.9). We present our approach to running workflow applications on distributed HPC resources, including systems without support for remote job submission. We show how our approach extends the benefits of scientific workflows, such as job and data management, to large-scale applications on Track 1 and Leadership class open-science HPC resources. We used our distributed workflow approach to perform CyberShake Study 13.4 on two new NSF open-science HPC computing resources, Blue Waters and Stampede, executing over 470 million tasks to calculate physics-based hazard curves for 286 locations in the Southern California region. For each location, we calculated seismic hazard curves with two different community velocity models and two different SGT codes, resulting in over 1100 hazard curves. We will report on the performance of this CyberShake study, four times larger than previous studies. Additionally, we will examine the challenges we face applying these workflow techniques to additional open-science HPC systems and discuss whether our workflow solutions continue to provide value to our large-scale PSHA calculations.

Shallow geology, sea-floor texture, and physiographic zones of Buzzards Bay, Massachusetts

USGS Publications Warehouse

Foster, David S.; Baldwin, Wayne E.; Barnhardt, Walter A.; Schwab, William C.; Ackerman, Seth D.; Andrews, Brian D.; Pendleton, Elizabeth A.

2015-01-07

Geologic, sediment texture, and physiographic zone maps characterize the sea floor of Buzzards Bay, Massachusetts. These maps were derived from interpretations of seismic-reflection profiles, high-resolution bathymetry, acoustic-backscatter intensity, bottom photographs, and surficial sediment samples. The interpretation of the seismic stratigraphy and mapping of glacial and Holocene marine units provided a foundation on which the surficial maps were created. This mapping is a result of a collaborative effort between the U.S. Geological Survey and the Massachusetts Office of Coastal Zone Management to characterize the surface and subsurface geologic framework offshore of Massachusetts.

Spatial distribution of intrinsic and scattering seismic attenuation in active volcanic islands - I: model and the case of Tenerife Island

NASA Astrophysics Data System (ADS)

Prudencio, Janire; Del Pezzo, Edoardo; García-Yeguas, Araceli; Ibáñez, Jesús M.

2013-12-01

The complex volcanic system of Tenerife Island is known to have a highly heterogeneous character, as recently confirmed by velocity tomography. We present new information derived from intrinsic quality factor inverse maps (Qi-1), scattering quality factor inverse maps (Qs-1) and total quality factor inverse maps (Qt-1) obtained for the same region. The data set used in this work is the result of the analysis of an active seismic experiment carried out, using offshore shots (air guns) recorded at over 85 onshore seismic stations. The estimates of the attenuation parameters are based on the assumption that the seismogram energy envelopes are determined by seismic energy diffusion processes occurring inside the island. Diffusion model parameters, proportional to Qi-1 and to Qs-1, are estimated from the inversion of the energy envelopes for any source-receiver couple. They are then weighted with a new graphical approach based on a Gaussian space probability function, which allowed us to create `2-D probabilistic maps' representing the space distribution of the attenuation parameters. The 2-D images obtained reveal the existence of a zone in the centre of the island characterized by the lowest attenuation effects. This effect is interpreted as highly rigid and cooled rocks. This low-attenuation region is bordered by zones of high attenuation, associated with the recent historical volcanic activity. We calculate the transport mean free path obtaining a value of around 4 km for the frequency range 6-12 Hz. This result is two orders of magnitude smaller than values calculated for the crust of the Earth. An absorption length between 10 and 14 km is associated with the average intrinsic attenuation parameter. These values, while small in the context of tectonic regions, are greater than those obtained in volcanic regions such as Vesuvius or Merapi. Such differences may be explained by the magnitude of the region of study, over three times larger than the aforementioned study areas. This also implies deeper sampling of the crust, which is evidenced by a change in the values of seismic attenuation. One important observation is that scattering attenuation dominates over the intrinsic effects, Qi being at least twice the value of Qs.

Advances in Predicting Magnetic Fields on the Far Side of the Sun

NASA Astrophysics Data System (ADS)

Lindsey, C. A.

2016-12-01

Techniques in local solar seismology applied to observations of seismic oscillations in the Sun's near hemisphere allow us to map large magnetic regions in the Sun's far hemisphere. Seismic signatures are not nearly as sensitive to magnetic flux as observations in electromagnetic radiation. However, they clearly identify and locate the 400 or so largest active regions in a typical solar cycle, i.e., those of most concern for space-weather forecasting. By themselves, seismic observations are insensitive to magnetic polarity. However, the Hale polarity law offers tantalizing avenues for guessing polarity distributions from seismic signatures as they evolve. I will review what we presently know about the relationship between seismic signatures of active regions and their magnetic and radiative properties, and offer a preliminary assessment of the potential of far-side seismic maps for space-weather forecasting in the coming decade.

Structural and Tectonic Map Along the Pacific-North America Plate Boundary in Northern Gulf of California, Sonora Desert and Valle de Mexicali, Mexico, from Seismic Reflection Evidence

NASA Astrophysics Data System (ADS)

Gonzalez-Escobar, M.; Suarez-Vidal, F.; Mendoza-Borunda, R.; Martin Barajas, A.; Pacheco-Romero, M.; Arregui-Estrada, S.; Gallardo-Mata, C.; Sanchez-Garcia, C.; Chanes-Martinez, J.

2012-12-01

Between 1978 and 1983, Petróleos Mexicanos (PEMEX) carried on an intense exploration program in the northern Gulf of California, the Sonora Desert and the southern part of the Mexicali Valley. This program was supported by a seismic reflection field operation. The collected seismic data was 2D, with travel time of 6 s recording, in 48 channels, and the source energy was: dynamite, vibroseis and air guns. Since 2007 to present time, the existing seismic data has been re-processing and ire-interpreting as part of a collaboration project between the PEMEX's Subdirección de Exploración (PEMEX) and CICESE. The study area is located along a large portion of the Pacific-North America plate boundary in the northern Gulf of California and the Southern part of the Salton Trough tectonic province (Mexicali Valley). We present the result of the processes reflection seismic lines. Many of the previous reported known faults were identify along with the first time described located within the study region. We identified regions with different degree of tectonic activity. In structural map it can see the location of many of these known active faults and their associated seismic activity, as well as other structures with no associated seismicity. Where some faults are mist placed they were deleted or relocated based on new information. We included historical seismicity for the region. We present six reflection lines that cross the aftershocks zone of the El Mayor-Cucapah earthquake of April 4, 2010 (Mw7.2). The epicenter of this earthquake and most of the aftershocks are located in a region where pervious to this earthquake no major earthquakes are been reported. A major result of this study is to demonstrate that there are many buried faults that increase the seismic hazard.

Urban seismic risk assessment: statistical repair cost data and probable structural losses based on damage scenario—correlation analysis

NASA Astrophysics Data System (ADS)

Eleftheriadou, Anastasia K.; Baltzopoulou, Aikaterini D.; Karabinis, Athanasios I.

2016-06-01

The current seismic risk assessment is based on two discrete approaches, actual and probable, validating afterwards the produced results. In the first part of this research, the seismic risk is evaluated from the available data regarding the mean statistical repair/strengthening or replacement cost for the total number of damaged structures (180,427 buildings) after the 7/9/1999 Parnitha (Athens) earthquake. The actual evaluated seismic risk is afterwards compared to the estimated probable structural losses, which is presented in the second part of the paper, based on a damage scenario in the referring earthquake. The applied damage scenario is based on recently developed damage probability matrices (DPMs) from Athens (Greece) damage database. The seismic risk estimation refers to 750,085 buildings situated in the extended urban region of Athens. The building exposure is categorized in five typical structural types and represents 18.80 % of the entire building stock in Greece. The last information is provided by the National Statistics Service of Greece (NSSG) according to the 2000-2001 census. The seismic input is characterized by the ratio, a g/ a o, where a g is the regional peak ground acceleration (PGA) which is evaluated from the earlier estimated research macroseismic intensities, and a o is the PGA according to the hazard map of the 2003 Greek Seismic Code. Finally, the collected investigated financial data derived from different National Services responsible for the post-earthquake crisis management concerning the repair/strengthening or replacement costs or other categories of costs for the rehabilitation of earthquake victims (construction and function of settlements for earthquake homeless, rent supports, demolitions, shorings) are used to determine the final total seismic risk factor.

Seismic Wave Amplification in Las Vegas: Site Characterization Measurements and Response Models

NASA Astrophysics Data System (ADS)

Louie, J. N.; Anderson, J. G.; Luke, B.; Snelson, C.; Taylor, W.; Rodgers, A.; McCallen, D.; Tkalcic, H.; Wagoner, J.

2004-12-01

As part of a multidisciplinary effort to understand seismic wave amplification in Las Vegas Valley, we conducted geotechnical and seismic refraction field studies, geologic and lithologic interpretation, and geophysical model building. Frequency-dependent amplifications (site response) and peak ground motions strongly correlate with site conditions as characterized by the models. The models include basin depths and velocities, which also correlate against ground motions. Preliminary geologic models were constructed from detailed geologic and fault mapping, logs of over 500 wells penetrating greater than 200 m depth, gravity-inversion results from the USGS, and USDA soil maps. Valley-wide refraction studies we conducted in 2002 and 2003 were inverted for constraints on basin geometry, and deep basin and basement P velocities with some 3-d control to depths of 5 km. Surface-wave studies during 2002-2004 characterized more than 75 sites within the Valley for shear velocity to depths exceeding 100 m, including all the legacy sites where nuclear-blast ground motions were recorded. The SASW and refraction-microtremor surface-surveying techniques proved to provide complementary, and coordinating Rayleigh dispersion-curve data at a dozen sites. Borehole geotechnical studies at a half-dozen sites confirmed the shear-velocity profiles that we derived from surface-wave studies. We then correlated all the geotechnical data against a detailed stratigraphic model, derived from drilling logs, to create a Valley-wide model for shallow site conditions. This well-log-based model predicts site measurements better than do models based solely on geologic or soil mapping.

Seismogenic faulting in the Meruoca granite, NE Brazil, consistent with a local weak fracture zone.

PubMed

Moura, Ana Catarina A; De Oliveira, Paulo H S; Ferreira, Joaquim M; Bezerra, Francisco H R; Fuck, Reinhardt A; Do Nascimento, Aderson F

2014-12-01

A sequence of earthquakes occurred in 2008 in the Meruoca granitic pluton, located in the northwestern part of the Borborema Province, NE Brazil. A seismological study defined the seismic activity occurring along the seismically-defined Riacho Fundo fault, a 081° striking, 8 km deep structure. The objective of this study was to analyze the correlation between this seismic activity and geological structures in the Meruoca granite. We carried out geological mapping in the epicentral area, analyzed the mineralogy of fault rocks, and compared the seismically-defined Riacho Fundo fault with geological data. We concluded that the seismically-defined fault coincides with ∼E-W-striking faults observed at outcrop scale and a swarm of Mesozoic basalt dikes. We propose that seismicity reactivated brittle structures in the Meruoca granite. Our study highlights the importance of geological mapping and mineralogical analysis in order to establish the relationships between geological structures and seismicity at a given area.

Seismogenic faulting in the Meruoca granite, NE Brazil, consistent with a local weak fracture zone.

PubMed

Moura, Ana Catarina A; Oliveira, Paulo H S DE; Ferreira, Joaquim M; Bezerra, Francisco H R; Fuck, Reinhardt A; Nascimento, Aderson F DO

2014-10-24

A sequence of earthquakes occurred in 2008 in the Meruoca granitic pluton, located in the northwestern part of the Borborema Province, NE Brazil. A seismological study defined the seismic activity occurring along the seismically-defined Riacho Fundo fault, a 081° striking, 8 km deep structure. The objective of this study was to analyze the correlation between this seismic activity and geological structures in the Meruoca granite. We carried out geological mapping in the epicentral area, analyzed the mineralogy of fault rocks, and compared the seismically-defined Riacho Fundo fault with geological data. We concluded that the seismically-defined fault coincides with ∼E-W-striking faults observed at outcrop scale and a swarm of Mesozoic basalt dikes. We propose that seismicity reactivated brittle structures in the Meruoca granite. Our study highlights the importance of geological mapping and mineralogical analysis in order to establish the relationships between geological structures and seismicity at a given area.

The North American upper mantle: density, composition, and evolution

USGS Publications Warehouse

Mooney, Walter D.; Kaban, Mikhail K.

2010-01-01

The upper mantle of North America has been well studied using various seismic methods. Here we investigate the density structure of the North American (NA) upper mantle based on the integrative use of the gravity field and seismic data. The basis of our study is the removal of the gravitational effect of the crust to determine the mantle gravity anomalies. The effect of the crust is removed in three steps by subtracting the gravitational contributions of (1) topography and bathymetry, (2) low-density sedimentary accumulations, and (3) the three-dimensional density structure of the crystalline crust as determined by seismic observations. Information regarding sedimentary accumulations, including thickness and density, are taken from published maps and summaries of borehole measurements of densities; the seismic structure of the crust is based on a recent compilation, with layer densities estimated from P-wave velocities. The resultant mantle gravity anomaly map shows a pronounced negative anomaly (−50 to −400 mGal) beneath western North America and the adjacent oceanic region and positive anomalies (+50 to +350 mGal) east of the NA Cordillera. This pattern reflects the well-known division of North America into the stable eastern region and the tectonically active western region. The close correlation of large-scale features of the mantle anomaly map with those of the topographic map indicates that a significant amount of the topographic uplift in western NA is due to buoyancy in the hot upper mantle, a conclusion supported by previous investigations. To separate the contributions of mantle temperature anomalies from mantle compositional anomalies, we apply an additional correction to the mantle anomaly map for the thermal structure of the uppermost mantle. The thermal model is based on the conversion of seismic shear-wave velocities to temperature and is consistent with mantle temperatures that are independently estimated from heat flow and heat production data. The thermally corrected mantle density map reveals density anomalies that are chiefly due to compositional variations. These compositional density anomalies cause gravitational anomalies that reach ~250 mGal. A pronounced negative anomaly (−50 to −200 mGal) is found over the Canadian shield, which is consistent with chemical depletion and a corresponding low density of the lithospheric mantle, also referred to as the mantle tectosphere. The strongest positive anomaly is coincident with the Gulf of Mexico and indicates a positive density anomaly in the upper mantle, possibly an eclogite layer that has caused subsidence in the Gulf. Two linear positive anomalies are also seen south of 40°N: one with a NE-SW trend in the eastern United States, roughly coincident with the Grenville-Appalachians, and a second with a NW-SE trend beneath the states of Texas, New Mexico, and Colorado. These anomalies are interpreted as being due to (1) the presence of remnants of an oceanic slab in the upper mantle beneath the Grenville-Appalachian suture and (2) mantle thickening caused by a period of shallow, flat subduction during the Laramie orogeny, respectively. Based on these geophysical results, the evolution of the NA upper mantle is depicted in a series of maps and cartoons that display the primary processes that have formed and modified the NA crust and lithospheric upper mantle.

Spatial correlation of shear-wave velocity in the San Francisco Bay Area sediments

USGS Publications Warehouse

Thompson, E.M.; Baise, L.G.; Kayen, R.E.

2007-01-01

Ground motions recorded within sedimentary basins are variable over short distances. One important cause of the variability is that local soil properties are variable at all scales. Regional hazard maps developed for predicting site effects are generally derived from maps of surficial geology; however, recent studies have shown that mapped geologic units do not correlate well with the average shear-wave velocity of the upper 30 m, Vs(30). We model the horizontal variability of near-surface soil shear-wave velocity in the San Francisco Bay Area to estimate values in unsampled locations in order to account for site effects in a continuous manner. Previous geostatistical studies of soil properties have shown horizontal correlations at the scale of meters to tens of meters while the vertical correlations are on the order of centimeters. In this paper we analyze shear-wave velocity data over regional distances and find that surface shear-wave velocity is correlated at horizontal distances up to 4 km based on data from seismic cone penetration tests and the spectral analysis of surface waves. We propose a method to map site effects by using geostatistical methods based on the shear-wave velocity correlation structure within a sedimentary basin. If used in conjunction with densely spaced shear-wave velocity profiles in regions of high seismic risk, geostatistical methods can produce reliable continuous maps of site effects. ?? 2006 Elsevier Ltd. All rights reserved.

Constraints Imposed by Rift Inheritance on the Compressional Reactivation of a Hyperextended Margin: Mapping Rift Domains in the North Iberian Margin and in the Cantabrian Mountains

NASA Astrophysics Data System (ADS)

Cadenas, P.; Fernández-Viejo, G.; Pulgar, J. A.; Tugend, J.; Manatschal, G.; Minshull, T. A.

2018-03-01

The Alpine Pyrenean-Cantabrian orogen developed along the plate boundary between Iberia and Europe, involving the inversion of Mesozoic hyperextended basins along the southern Biscay margin. Thus, this margin represents a natural laboratory to analyze the control of structural rift inheritance on the compressional reactivation of a continental margin. With the aim to identify former rift domains and investigate their role during the subsequent compression, we performed a structural analysis of the central and western North Iberian margin, based on the interpretation of seismic reflection profiles and local constraints from drill-hole data. Seismic interpretations and published seismic velocity models enabled the development of crustal thickness maps that helped to constrain further the offshore and onshore segmentation. Based on all these constraints, we present a rift domain map across the central and western North Iberian margin, as far as the adjacent western Cantabrian Mountains. Furthermore, we provide a first-order description of the margin segmentation resulting from its polyphase tectonic evolution. The most striking result is the presence of a hyperthinned domain (e.g., Asturian Basin) along the central continental platform that is bounded to the north by the Le Danois High, interpreted as a rift-related continental block separating two distinctive hyperextended domains. From the analysis of the rift domain map and the distribution of reactivation structures, we conclude that the landward limit of the necking domain and the hyperextended domains, respectively, guide and localize the compressional overprint. The Le Danois block acted as a local buttress, conditioning the inversion of the Asturian Basin.

Seismic, side-scan survey, diving, and coring data analyzed by a Macintosh II sup TM computer and inexpensive software provide answers to a possible offshore extension of landslides at Palos Verdes Peninsula, California

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

Dill, R.F.; Slosson, J.E.; McEachen, D.B.

1990-05-01

A Macintosh II{sup TM} computer and commercially available software were used to analyze and depict the topography, construct an isopach sediment thickness map, plot core positions, and locate the geology of an offshore area facing an active landslide on the southern side of Palos Verdes Peninsula California. Profile data from side scan sonar, 3.5 kHz, and Boomer subbottom, high-resolution seismic, diving, echo sounder traverses, and cores - all controlled with a mini Ranger II navigation system - were placed in MacGridzo{sup TM} and WingZ{sup TM} software programs. The computer-plotted data from seven sources were used to construct maps with overlaysmore » for evaluating the possibility of a shoreside landslide extending offshore. The poster session describes the offshore survey system and demonstrates the development of the computer data base, its placement into the MacGridzo{sup TM} gridding program, and transfer of gridded navigational locations to the WingZ{sup TM} data base and graphics program. Data will be manipulated to show how sea-floor features are enhanced and how isopach data were used to interpret the possibility of landslide displacement and Holocene sea level rise. The software permits rapid assessment of data using computerized overlays and a simple, inexpensive means of constructing and evaluating information in map form and the preparation of final written reports. This system could be useful in many other areas where seismic profiles, precision navigational locations, soundings, diver observations, and core provide a great volume of information that must be compared on regional plots to develop of field maps for geological evaluation and reports.« less

Modifications to risk-targeted seismic design maps for subduction and near-fault hazards

USGS Publications Warehouse

Liel, Abbie B.; Luco, Nicolas; Raghunandan, Meera; Champion, C.; Haukaas, Terje

2015-01-01

ASCE 7-10 introduced new seismic design maps that define risk-targeted ground motions such that buildings designed according to these maps will have 1% chance of collapse in 50 years. These maps were developed by iterative risk calculation, wherein a generic building collapse fragility curve is convolved with the U.S. Geological Survey hazard curve until target risk criteria are met. Recent research shows that this current approach may be unconservative at locations where the tectonic environment is much different than that used to develop the generic fragility curve. This study illustrates how risk-targeted ground motions at selected sites would change if generic building fragility curve and hazard assessment were modified to account for seismic risk from subduction earthquakes and near-fault pulses. The paper also explores the difficulties in implementing these changes.

Seismic Risk Studies in the United States.

ERIC Educational Resources Information Center

Algermissen, S.T.

A new seismic risk map of the United States is presented, along with strain release and maximum Modified Mercalli intesity maps of the country. Frequency of occurrence of damaging earthquakes was not considered in zone ratings, but included frequency studies may aid interpretation. Discussion of methods is included with review of calculations. (MH)

Landslide inventories: The essential part of seismic landslide hazard analyses

USGS Publications Warehouse

Harp, E.L.; Keefer, D.K.; Sato, H.P.; Yagi, H.

2011-01-01

A detailed and accurate landslide inventory is an essential part of seismic landslide hazard analysis. An ideal inventory would cover the entire area affected by an earthquake and include all of the landslides that are possible to detect down to sizes of 1-5. m in length. The landslides must also be located accurately and mapped as polygons depicting their true shapes. Such mapped landslide distributions can then be used to perform seismic landslide hazard analysis and other quantitative analyses. Detailed inventory maps of landslide triggered by earthquakes began in the early 1960s with the use of aerial photography. In recent years, advances in technology have resulted in the accessibility of satellite imagery with sufficiently high resolution to identify and map all but the smallest of landslides triggered by a seismic event. With this ability to view any area of the globe, we can acquire imagery for any earthquake that triggers significant numbers of landslides. However, a common problem of incomplete coverage of the full distributions of landslides has emerged along with the advent of high resolution satellite imagery. ?? 2010.

GIS-based seismic shaking slope vulnerability map of Sicily (Central Mediterranean)

NASA Astrophysics Data System (ADS)

Nigro, Fabrizio; Arisco, Giuseppe; Perricone, Marcella; Renda, Pietro; Favara, Rocco

2010-05-01

Earthquakes often represent very dangerouses natural events in terms of human life and economic losses and their damage effects are amplified by the synchronous occurrence of seismically-induced ground-shaking failures in wide regions around the seismogenic source. In fact, the shaking associated with big earthquakes triggers extensive landsliding, sometimes at distances of more than 100 km from the epicenter. The active tectonics and the geomorphic/morphodinamic pattern of the regions affected by earthquakes contribute to the slopes instability tendency. In fact, earthquake-induced groun-motion loading determines inertial forces activation within slopes that, combined with the intrinsic pre-existing static forces, reduces the slope stability towards its failure. Basically, under zero-shear stress reversals conditions, a catastrophic failure will take place if the earthquake-induced shear displacement exceeds the critical level of undrained shear strength to a value equal to the gravitational shear stress. However, seismic stability analyses carried out for various infinite slopes by using the existing Newmark-like methods reveal that estimated permanent displacements smaller than the critical value should also be regarded as dangerous for the post-earthquake slope safety, in terms of human activities use. Earthquake-induced (often high-speed) landslides are among the most destructive phenomena related to slopes failure during earthquakes. In fact, damage from earthquake-induced landslides (and other ground-failures), sometimes exceeds the buildings/infrastructures damage directly related to ground-shaking for fault breaking. For this matter, several hearthquakes-related slope failures methods have been developed, for the evaluation of the combined hazard types represented by seismically ground-motion landslides. The methodologies of analysis of the engineering seismic risk related to the slopes instability processes is often achieved through the evaluation of the permanent displacement potentially induced by an seismic scenario. Such methodologies found on the consideration that the conditions of seismic stability and the post-seismic functionality of engineering structures are tightly related to the entity of the permanent deformations that an earthquake can induce. Regarding the existing simplified procedures among slope stability models, Newmark's model is often used to derive indications about slope instabilities due to earthquakes. In this way, we have evaluated the seismically-induced landslides hazard in Sicily (Central Mediterranean) using the Newmark-like model. In order to determine the map distribution of the seismic ground-acceleration from an earthquake scenario, the attenuation-law of Sabetta & Pugliese has been used, analyzing some seismic recordings occurred in Italy. Also, by evaluating permanent displacements, the correlation of Ambraseys & Menu has been assumed. The seismic shaking slope vulnerability map of Sicily has been carried out using GIS application, also considering max seismic ground-acceleration peak distribution (in terms of exceedance probability for fixed time), slope acclivity, cohesion/angle of internal friction of outcropping rocks, allowing the zoning of the unstable slopes under seismic forces.

Seismic lateral prediction in chalky limestone reservoirs offshore Qatar

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

Rubbens, I.B.H.M.; Murat, R.C.; Vankeulen, J.

Following the discovery of non-structurally trapped oil accumulations in Cretaceous chalky reservoirs on the northern flank of the North Dome offshore QATAR, a seismic lateral prediction study was carried out for QATAR GENERAL PETROLEUM CORPORATION (Offshore Operations). The objectives of this study were to assist in the appraisal of these oil accumulations by predicting their possible lateral extent and to investigate if the technique applied could be used as a basis for further exploration of similar oil prospects in the area. Wireline logs of eight wells and some 1000 km of high quality seismic data were processed into acoustic impedancemore » (A.I.) logs and seismic A.I. sections. Having obtained a satisfactory match of the A.I. well logs and the A.I. of the seismic traces at the well locations, relationships were established by the use of well log data which allowed the interpretation of the seismic A.I. in terms of reservoir quality. Measurements of the relevant A.I. characteristics were then carried out by computer along all seismic lines and porosity distribution maps prepared for some of the reservoirs. These maps, combined with detailed seismic depth contour maps at reservoir tops, lead to definition of good reservoir development areas downdip from poor reservoir quality zones i.e. of the stratigraphic trap areas, and drilling locations could thus be proposed. The system remains to be adequately calibrated when core material becomes available in the area of study.« less

Performance of USGS one-year earthquake hazard map for natural and induced seismicity in the central and eastern United States

NASA Astrophysics Data System (ADS)

Brooks, E. M.; Stein, S.; Spencer, B. D.; Salditch, L.; Petersen, M. D.; McNamara, D. E.

2017-12-01

Seismicity in the central United States has dramatically increased since 2008 due to the injection of wastewater produced by oil and gas extraction. In response, the USGS created a one-year probabilistic hazard model and map for 2016 to describe the increased hazard posed to the central and eastern United States. Using the intensity of shaking reported to the "Did You Feel It?" system during 2016, we assess the performance of this model. Assessing the performance of earthquake hazard maps for natural and induced seismicity is conceptually similar but has practical differences. Maps that have return periods of hundreds or thousands of years— as commonly used for natural seismicity— can be assessed using historical intensity data that also span hundreds or thousands of years. Several different features stand out when assessing the USGS 2016 seismic hazard model for the central and eastern United States from induced and natural earthquakes. First, the model can be assessed as a forecast in one year, because event rates are sufficiently high to permit evaluation with one year of data. Second, because these models are projections from the previous year thus implicitly assuming that fluid injection rates remain the same, misfit may reflect changes in human activity. Our results suggest that the model was very successful by the metric implicit in probabilistic hazard seismic assessment: namely, that the fraction of sites at which the maximum shaking exceeded the mapped value is comparable to that expected. The model also did well by a misfit metric that compares the spatial patterns of predicted and maximum observed shaking. This was true for both the central and eastern United States as a whole, and for the region within it with the highest amount of seismicity, Oklahoma and its surrounding area. The model performed least well in northern Texas, over-stating hazard, presumably because lower oil and gas prices and regulatory action reduced the water injection volume relative to the previous year. These results imply that such hazard maps have the potential to be valuable tools for policy makers and regulators in managing the seismic risks associated with unconventional oil and gas production.

Correlation of Geophysical and Geotechnical Methods for Sediment Mapping in Sungai Batu, Kedah

NASA Astrophysics Data System (ADS)

Zakaria, M. T.; Taib, A.; Saidin, M. M.; Saad, R.; Muztaza, N. M.; Masnan, S. S. K.

2018-04-01

Exploration geophysics is widely used to map the subsurface characteristics of a region, to understand the underlying rock structures and spatial distribution of rock units. 2-D resistivity and seismic refraction methods were conducted in Sungai Batu locality with objective to identify and map the sediment deposit with correlation of borehole record. 2-D resistivity data was acquire using ABEM SAS4000 system with Pole-dipole array and 2.5 m minimum electrode spacing while for seismic refraction ABEM MK8 seismograph was used to record the seismic data and 5 kg sledgehammer used as a seismic source with geophones interval of 5 m spacing. The inversion model of 2-D resistivity result shows that, the resistivity values <100 Ωm was interpreted as saturated zone with while high resistivity values >500 Ωm as the hard layer for this study area. The seismic result indicates that the velocity values <2000 m/s represent as the highly-weathered soil consists of clay and sand while high velocity values >3600 m/s interpreted as the hard layer in this locality.

GeoMapApp as a platform for visualizing marine data from Polar Regions

NASA Astrophysics Data System (ADS)

Nitsche, F. O.; Ryan, W. B.; Carbotte, S. M.; Ferrini, V.; Goodwillie, A. M.; O'hara, S. H.; Weissel, R.; McLain, K.; Chinhong, C.; Arko, R. A.; Chan, S.; Morton, J. J.; Pomeroy, D.

2012-12-01

To maximize the investment in expensive fieldwork the resulting data should be re-used as much as possible. In addition, unnecessary duplication of data collection effort should be avoided. This becomes even more important if access to field areas is as difficult and expensive as it is in Polar Regions. Making existing data discoverable in an easy to use platform is key to improve re-use and avoid duplication. A common obstacle is that use of existing data is often limited to specialists who know of the data existence and also have the right tools to view and analyze these data. GeoMapApp is a free, interactive, map based tool that allows users to discover, visualize, and analyze a large number of data sets. In addition to a global view, it provides polar map projections for displaying data in Arctic and Antarctic areas. Data that have currently been added to the system include Arctic swath bathymetry data collected from the USCG icebreaker Healy. These data are collected almost continuously including from cruises where bathymetry is not the main objective and for which existence of the acquired data may not be well known. In contrast, existence of seismic data from the Antarctic continental margin is well known in the seismic community. They are archived at and can be accessed through the Antarctic Seismic Data Library System (SDLS). Incorporating these data into GeoMapApp makes an even broader community aware of these data and the custom interface, which includes capabilities to visualize and explore these data, allows users without specific software or knowledge of the underlying data format to access the data. In addition to investigating these datasets, GeoMapApp provides links to the actual data sources to allow specialists the opportunity to re-use the original data. Important identification of data sources and data references are achieved on different levels. For access to the actual Antarctic seismic data GeoMapApp links to the SDLS site, where users have to register before downloading the data and where they are informed about data owners. For the swath bathymetry data GeoMapApp links to an IEDA/MGDS web page for each cruise containing detailed information about investigators and surveys.

Impacts of potential seismic landslides on lifeline corridors.

DOT National Transportation Integrated Search

2015-02-01

This report presents a fully probabilistic method for regional seismically induced landslide hazard analysis and : mapping. The method considers the most current predictions for strong ground motions and seismic sources : through use of the U.S.G.S. ...

Interactive Geophysical Mapping on the Web

NASA Astrophysics Data System (ADS)

Meertens, C.; Hamburger, M.; Estey, L.; Weingroff, M.; Deardorff, R.; Holt, W.

2002-12-01

We have developed a set of interactive, web-based map utilities that make geophysical results accessible to a large number and variety of users. These tools provide access to pre-determined map regions via a simple Html/JavaScript interface or to user-selectable areas using a Java interface to a Generic Mapping Tools (GMT) engine. Users can access a variety of maps, satellite images, and geophysical data at a range of spatial scales for the earth and other planets of the solar system. Developed initially by UNAVCO for study of global-scale geodynamic processes, users can choose from a variety of base maps (satellite mosaics, global topography, geoid, sea-floor age, strain rate and seismic hazard maps, and others) and can then add a number of geographic and geophysical overlays for example coastlines, political boundaries, rivers and lakes, NEIC earthquake and volcano locations, stress axes, and observed and model plate motion and deformation velocity vectors representing a compilation of 2933 geodetic measurements from around the world. The software design is flexible allowing for construction of special editions for different target audiences. Custom maps been implemented for UNAVCO as the "Jules Verne Voyager" and "Voyager Junior", for the International Lithosphere Project's "Global Strain Rate Map", and for EarthScope Education and Outreach as "EarthScope Voyager Jr.". For the later, a number of EarthScope-specific features have been added, including locations of proposed USArray (seismic), Plate Boundary Observatory (geodetic), and San Andreas Fault Observatory at Depth sites plus detailed maps and geographically referenced examples of EarthScope-related scientific investigations. In addition, we are developing a website that incorporates background materials and curricular activities that encourage users to explore Earth processes. A cluster of map processing computers and nearly a terabyte of disk storage has been assembled to power the generation of interactive maps and provide space for a very large collection of map data. A portal to these map tools can be found at: http://jules.unavco.ucar.edu.

WebEQ: a web-GIS System to collect, display and query data for the management of the earthquake emergency in Central Italy

NASA Astrophysics Data System (ADS)

Carbone, Gianluca; Cosentino, Giuseppe; Pennica, Francesco; Moscatelli, Massimiliano; Stigliano, Francesco

2017-04-01

After the strong earthquakes that hit central Italy in recent months, the Center for Seismic Microzonation and its applications (CentroMS) was commissioned by the Italian Department of Civil Protection to conduct the study of seismic microzonation of the territories affected by the earthquake of August 24, 2016. As part of the activities of microzonation, IGAG CNR has created WebEQ, a management tool of the data that have been acquired by all participants (i.e., more than twenty research institutes and university departments). The data collection was organized and divided into sub-areas, assigned to working groups with multidisciplinary expertise in geology, geophysics and engineering. WebEQ is a web-GIS System that helps all the subjects involved in the data collection activities, through tools aimed at data uploading and validation, and with a simple GIS interface to display, query and download geographic data. WebEQ is contributing to the creation of a large database containing geographical data, both vector and raster, from various sources and types: - Regional Technical Map em Geological and geomorphological maps em Data location maps em Maps of microzones homogeneous in seismic perspective and seismic microzonation maps em National strong motion network location. Data loading is done through simple input masks that ensure consistency with the database structure, avoiding possible errors and helping users to interact with the map through user-friendly tools. All the data are thematized through standardized symbologies and colors (Gruppo di lavoro MS 2008), in order to allow the easy interpretation by all users. The data download tools allow data exchange between working groups and the scientific community to benefit from the activities. The seismic microzonation activities are still ongoing. WebEQ is enabling easy management of large amounts of data and will form a basis for the development of tools for the management of the upcoming seismic emergencies.

Bedrock mapping of buried valley networks using seismic reflection and airborne electromagnetic data

NASA Astrophysics Data System (ADS)

Oldenborger, G. A.; Logan, C. E.; Hinton, M. J.; Pugin, A. J.-M.; Sapia, V.; Sharpe, D. R.; Russell, H. A. J.

2016-05-01

In glaciated terrain, buried valleys often host aquifers that are significant groundwater resources. However, given the range of scales, spatial complexity and depth of burial, buried valleys often remain undetected or insufficiently mapped. Accurate and thorough mapping of bedrock topography is a crucial step in detecting and delineating buried valleys and understanding formative valley processes. We develop a bedrock mapping procedure supported by the combination of seismic reflection data and helicopter time-domain electromagnetic data with water well records for the Spiritwood buried valley aquifer system in Manitoba, Canada. The limited spatial density of water well bedrock observations precludes complete depiction of the buried valley bedrock topography and renders the water well records alone inadequate for accurate hydrogeological model building. Instead, we leverage the complementary strengths of seismic reflection and airborne electromagnetic data for accurate local detection of the sediment-bedrock interface and for spatially extensive coverage, respectively. Seismic reflection data are used to define buried valley morphology in cross-section beneath survey lines distributed over a regional area. A 3D model of electrical conductivity is derived from inversion of the airborne electromagnetic data and used to extrapolate buried valley morphology over the entire survey area. A spatially variable assignment of the electrical conductivity at the bedrock surface is applied to different features of the buried valley morphology identified in the seismic cross-sections. Electrical conductivity is then used to guide construction of buried valley shapes between seismic sections. The 3D locus of points defining each morphological valley feature is constructed using a path optimization routine that utilizes deviation from the assigned electrical conductivities as the cost function. Our resulting map represents a bedrock surface of unprecedented detail with more complexity than has been suggested by previous investigations. Our procedure is largely data-driven with an adaptable degree of expert user input that provides a clear protocol for incorporating different types of geophysical data into the bedrock mapping procedure.

An alternative approach to probabilistic seismic hazard analysis in the Aegean region using Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Weatherill, Graeme; Burton, Paul W.

2010-09-01

The Aegean is the most seismically active and tectonically complex region in Europe. Damaging earthquakes have occurred here throughout recorded history, often resulting in considerable loss of life. The Monte Carlo method of probabilistic seismic hazard analysis (PSHA) is used to determine the level of ground motion likely to be exceeded in a given time period. Multiple random simulations of seismicity are generated to calculate, directly, the ground motion for a given site. Within the seismic hazard analysis we explore the impact of different seismic source models, incorporating both uniform zones and distributed seismicity. A new, simplified, seismic source model, derived from seismotectonic interpretation, is presented for the Aegean region. This is combined into the epistemic uncertainty analysis alongside existing source models for the region, and models derived by a K-means cluster analysis approach. Seismic source models derived using the K-means approach offer a degree of objectivity and reproducibility into the otherwise subjective approach of delineating seismic sources using expert judgment. Similar review and analysis is undertaken for the selection of peak ground acceleration (PGA) attenuation models, incorporating into the epistemic analysis Greek-specific models, European models and a Next Generation Attenuation model. Hazard maps for PGA on a "rock" site with a 10% probability of being exceeded in 50 years are produced and different source and attenuation models are compared. These indicate that Greek-specific attenuation models, with their smaller aleatory variability terms, produce lower PGA hazard, whilst recent European models and Next Generation Attenuation (NGA) model produce similar results. The Monte Carlo method is extended further to assimilate epistemic uncertainty into the hazard calculation, thus integrating across several appropriate source and PGA attenuation models. Site condition and fault-type are also integrated into the hazard mapping calculations. These hazard maps are in general agreement with previous maps for the Aegean, recognising the highest hazard in the Ionian Islands, Gulf of Corinth and Hellenic Arc. Peak Ground Accelerations for some sites in these regions reach as high as 500-600 cm s -2 using European/NGA attenuation models, and 400-500 cm s -2 using Greek attenuation models.

A seismological model for earthquakes induced by fluid extraction from a subsurface reservoir

NASA Astrophysics Data System (ADS)

Bourne, S. J.; Oates, S. J.; van Elk, J.; Doornhof, D.

2014-12-01

A seismological model is developed for earthquakes induced by subsurface reservoir volume changes. The approach is based on the work of Kostrov () and McGarr () linking total strain to the summed seismic moment in an earthquake catalog. We refer to the fraction of the total strain expressed as seismic moment as the strain partitioning function, α. A probability distribution for total seismic moment as a function of time is derived from an evolving earthquake catalog. The moment distribution is taken to be a Pareto Sum Distribution with confidence bounds estimated using approximations given by Zaliapin et al. (). In this way available seismic moment is expressed in terms of reservoir volume change and hence compaction in the case of a depleting reservoir. The Pareto Sum Distribution for moment and the Pareto Distribution underpinning the Gutenberg-Richter Law are sampled using Monte Carlo methods to simulate synthetic earthquake catalogs for subsequent estimation of seismic ground motion hazard. We demonstrate the method by applying it to the Groningen gas field. A compaction model for the field calibrated using various geodetic data allows reservoir strain due to gas extraction to be expressed as a function of both spatial position and time since the start of production. Fitting with a generalized logistic function gives an empirical expression for the dependence of α on reservoir compaction. Probability density maps for earthquake event locations can then be calculated from the compaction maps. Predicted seismic moment is shown to be strongly dependent on planned gas production.

Development of direct multi-hazard susceptibility assessment method for post-earthquake reconstruction planning in Nepal

NASA Astrophysics Data System (ADS)

Mavrouli, Olga; Rana, Sohel; van Westen, Cees; Zhang, Jianqiang

2017-04-01

After the devastating 2015 Gorkha earthquake in Nepal, reconstruction activities have been delayed considerably, due to many reasons, of a political, organizational and technical nature. Due to the widespread occurrence of co-seismic landslides, and the expectation that these may be aggravated or re-activated in future years during the intense monsoon periods, there is a need to evaluate for thousands of sites whether these are suited for reconstruction. In this evaluation multi-hazards, such as rockfall, landslides, debris flow, and flashfloods should be taken into account. The application of indirect knowledge-based, data-driven or physically-based approaches is not suitable due to several reasons. Physically-based models generally require a large number of parameters, for which data is not available. Data-driven, statistical methods, depend on historical information, which is less useful after the occurrence of a major event, such as an earthquake. Besides, they would lead to unacceptable levels of generalization, as the analysis is done based on rather general causal factor maps. The same holds for indirect knowledge-driven methods. However, location-specific hazards analysis is required using a simple method that can be used by many people at the local level. In this research, a direct scientific method was developed where local level technical people can easily and quickly assess the post-earthquake multi hazards following a decision tree approach, using an app on a smartphone or tablet. The methods assumes that a central organization, such as the Department of Soil Conservation and Watershed Management, generates spatial information beforehand that is used in the direct assessment at a certain location. Pre-earthquake, co-seismic and post-seismic landslide inventories are generated through the interpretation of Google Earth multi-temporal images, using anaglyph methods. Spatial data, such as Digital Elevation Models, land cover maps, and geological maps are used in a GIS to generate Terrain Units in a semi-automated manner, which are further edited using stereo-image interpretation. Source areas for rockfall and debris flows are outlined from the factor maps, and historical inventory, and regional scale empirical runout models are used to define areas that might be affected. This data is then used in the field in an application that guides the user through the decision tree by asking a number of questions, which can be answered by using the existing data, and by direct field observations. The method was applied in a part of Rasuwa district, which was seriously affected by co-seismic and post-seismic mass movements, leading to the evacuation of a number of village, and temporary closure of a number of hydropower construction projects.

Integrate urban‐scale seismic hazard analyses with the U.S. National Seismic Hazard Model

USGS Publications Warehouse

Moschetti, Morgan P.; Luco, Nicolas; Frankel, Arthur; Petersen, Mark D.; Aagaard, Brad T.; Baltay, Annemarie S.; Blanpied, Michael; Boyd, Oliver; Briggs, Richard; Gold, Ryan D.; Graves, Robert; Hartzell, Stephen; Rezaeian, Sanaz; Stephenson, William J.; Wald, David J.; Williams, Robert A.; Withers, Kyle

2018-01-01

For more than 20 yrs, damage patterns and instrumental recordings have highlighted the influence of the local 3D geologic structure on earthquake ground motions (e.g., M">M 6.7 Northridge, California, Gao et al., 1996; M">M 6.9 Kobe, Japan, Kawase, 1996; M">M 6.8 Nisqually, Washington, Frankel, Carver, and Williams, 2002). Although this and other local‐scale features are critical to improving seismic hazard forecasts, historically they have not been explicitly incorporated into the U.S. National Seismic Hazard Model (NSHM, national model and maps), primarily because the necessary basin maps and methodologies were not available at the national scale. Instead,...

Understanding the paleo environment in the Danish North Sea using 2D and 3D seismic analyses

NASA Astrophysics Data System (ADS)

Prins, Lasse K.; Clausen, Ole R.; Andresen, Katrine J.

2017-04-01

This study presents the first detailed and integrated mapping of buried Quaternary valleys, river systems and iceberg scourings from the Danish North Sea region. The mapped features coincide spatially but have very different characteristics and incision levels which allow us to constrain their relative timing and differentiate their environment of formation (subglacial, proglacial and marine). The results of the study bring new critical information regarding the paleoenvironment of the North Sea Basin during the latest Quaternary deglaciation period and our analysis provide a well-tested workflow for utilizing 2D and 3D seismic data in relation to paleogeographical reconstructions. Our analysis is based on interpretation of conventional 3D seismic and high-resolution sparker data from the Southern Danish Central Graben. The project forms part of the portfolio for the 'Danish Hydrocarbon Research and Technology Centre' and aims at building a high-resolution 3D geological-geotechnical model of the shallow subsurface by using geophysical data combined with geological and geotechnical data from shallow borings. One of the objectives is to map potential geohazards for offshore installations such as buried valleys and constrain their geotechnical properties. The central North Sea is known to have been covered by glaciers several times during the Quaternary with climate changing between arctic and boreal. Marine conditions periodically prevailed and large river systems mainly from central Europe dominated during periods of subaerial exposure. Hence, many buried erosional incisions, primarily tunnel valleys but also river systems, can be observed within the upper 200-400 meters of the Quaternary succession throughout the central North Sea region. A high-resolution mapping of the infill of the tunnel valleys and river systems have however not previously been presented. Our analysis shows that within the study area at least four generations of tunnel valley formation and river system incisions can be mapped. The tunnel valleys have a strong NE-SW orientation and are typically characterized by an irregular base. The fluvial river systems which are the youngest, are smaller, typically with an anastomosing appearance. They generally have an NW-SE strike perpendicular to the older tunnel valleys. Clear sedimentary structures can be recognized on the high-resolution 2D seismic data indicating a complex history of cut and fill. In general, the study area displays a very heterogenic sedimentation pattern with varying valley types and significant lateral variations within the same valleys revealing a subtle interplay between incision and infilling. In some areas we furthermore see a distinct control of the river system morphology by deeper salt structures adding to the complexity of controlling factors for the rivers and tunnel valleys in the study area. The results of the study provide valuable information on the evolution of the Quaternary ice-sheets and drainage patterns and hence exemplify the use of seismic data for Quaternary paleo-environmental studies. With the good control on the distribution and infill of buried valleys and river systems, the study furthermore provides the first constrain to a detailed 3D model of different litho-facies based on seismic facies analysis combined with information from shallow borings.

Hawaiian Volcano Observatory Seismic Data, January to December 2008

USGS Publications Warehouse

Nakata, Jennifer S.; Okubo, Paul G.

2009-01-01

The U.S. Geological Survey (USGS), Hawaiian Volcano Observatory (HVO) summary presents seismic data gathered during the year. The seismic summary is offered without interpretation as a source of preliminary data and is complete in that most data for events of M greater than 1.5 are included. All latitude and longitude references in this report are stated in Old Hawaiian Datum. The HVO summaries have been published in various forms since 1956. Summaries prior to 1974 were issued quarterly, but cost, convenience of preparation and distribution, and the large quantities of data necessitated an annual publication, beginning with Summary 74 for the year 1974. Beginning in 2004, summaries are simply identified by the year, rather than by summary number. Summaries originally issued as administrative reports were republished in 2007 as Open-File Reports. All the summaries since 1956 are listed at http://geopubs.wr.usgs.gov/ (last accessed 09/21/2009). In January 1986, HVO adopted CUSP (California Institute of Technology USGS Seismic Processing). Summary 86 includes a description of the seismic instrumentation, calibration, and processing used in recent years. The present summary includes background information about the seismic network to provide the end user an understanding of the processing parameters and how the data were gathered. A report by Klein and Koyanagi (1980) tabulates instrumentation, calibration, and recording history of each seismic station in the network. It is designed as a reference for users of seismograms and phase data and includes and augments the information in the station table in this summary. Figures 11-14 are maps showing computer-located hypocenters. The maps were generated using the Generic Mapping Tools (GMT http://gmt.soest.hawaii.edu/, last accessed 09/21/2009) in place of traditional Qplot maps.

Paleostress Analysis with Reflection Seismic Data: Example from the Songliao Basin, Northeast China

NASA Astrophysics Data System (ADS)

Liu, G.; Persaud, P.; Zhang, Y.

2017-12-01

Currently paleostress inversion using fault-slip data is a well established approach. However, the deformation history contained in folds has not yet been fully utilized to determine the paleostress field. By applying a 2D FFT-based algorithm to a structure or isopach map derived from reflection seismic data, we find a new way of exploiting the information preserved in folds to determine the paleostress. Our method requires that the strata have a large areal extent and are well preserved. After pre-processing the maps, we find that in the frequency-wavenumber (F-K) domain, folds with similar strikes are grouped into spectrum belts. Each belt parallels the short axis of the fold group and can therefore indicate the direction of the associated maximum horizontal stress. Some information on the relative chronology of stresses can be deduced by comparing the structure and isopach spectrum maps, e.g., if the structure spectrum map has one more spectrum belt than that of the isopach map (an approximate paleo-structure map of the corresponding stratum), we can conclude that the indicated stress postdated the deposition of the stratum. We selected three Late Cretaceous strata from a 3D seismic survey located in the intracontinental Songliao Basin, northeast China. The Songliao has experienced four episodes of deformation: mantle upwelling, rifting, postrift thermal subsidence and structural inversion (Feng et al., 2009). The selected strata were deposited during the third stage. Three structure and two isopach maps were decomposed in the F-K domain. Spectral analysis of the lower isopach map shows eight paleostress directions. We also identify a ninth paleostress in addition to the previous eight from the structure maps and the upper isopach map. The eight stress directions that exist in both the isopach and structure maps may have been active throughout the time period spanned by the strata. We interpret the ninth paleostress as being active after the deposition of the lower stratum. The derived paleostress field fits well with the interpretations of other workers and provides more accurate stress directions and chronology. We further apply this technique to the Central Sichuan basin, southwest China, and confirm the multi-directional compressional tectonics of that basin.

Mapping the North Sea base-Quaternary: using 3D seismic to fill a gap in the geological record

NASA Astrophysics Data System (ADS)

Lamb, Rachel; Huuse, Mads; Stewart, Margaret; Brocklehurst, Simon H.

2014-05-01

The identification and mapping of the base-Quaternary boundary in the central parts of the North Sea is problematic due to the change from an unconformable transition between Pliocene and Pleistocene deltaic deposits in the southern North Sea to a conformable one further north (Sejrup et al 1991; Gatliff et al 1994). The best estimates of the transition use seismic reflection data to identify a 'crenulated reflector' (Buckley 2012), or rely on correlating sparse biostratigraphy (Cameron et al 1987). Recent integration of biostratigraphy, pollen analysis, paleomagnetism and amino acid analysis in the Dutch and Danish sectors (Rasmussen et al 2005; Kuhlmann et al 2006) allows greater confidence in the correlation to a regional 3D seismic dataset and show that the base-Quaternary can be mapped across the entire basin. The base-Quaternary has been mapped using the PGS MegaSurvey dataset from wells in the Danish Sector along the initially unconformable horizon and down the delta front into the more conformable basin giving a high degree of confidence in the horizon pick. The mapped horizon is presented here alongside the difference between this new interpretation and the previously interpreted base-Quaternary (Buckley 2012). The revised base-Quaternary surface reaches a depth of 1248 ms TWT or approximately 1120 m (assuming average velocity of 1800 m/s) showing an elongate basin shape that follows the underlying structure of the Central Graben. The difference between the revised base-Quaternary and the traditional base-Quaternary reaches a maximum of over 600 ms TWT or approximately 540 m in the south-west with over 300 ms TWT or approximately 270 m at the Josephine well (56° 36.11'N, 2° 27.09'E) in the centre of the basin. Mapping this new base-Quaternary allows for the interpretation of the paleo-envionrment during the earliest Quaternary. Seismic attribute analysis indicates a deep water basin with sediment deposition from multiple deltas and redistribution by deep water currents. This has strong implications for both the Quaternary climate archive and petroleum systems in the North Sea. Key Words: base-Quaternary; chronostratigraphy: seismic interpretation; paleoenvironments References Buckley, F.A., (2012) 'An Early Pleistocene grounded ice sheet in the Central North Sea' From: Huuse, M., Redfern, J., Le Heron, D.P., Dixon, R.J., Moscariello, A., Craig, J. (eds) 'Glaciogenic reservoirs and Hydrocarbon Systems' Geological Society, London, Special Publications, 368 Cameron, T.D.J., Stoker, M.S., Long, D., (1987) 'The history of Quaternary sedimentation in the UK sector of the North Sea Basin' Journal of the Geological Society, 144, 43-58 Gatliff, R.W, Richards, P.C, Smith, K, Graham, C.C, McCormac, M, Smith, N.J.P, Long, D, Cameron, T.D.J, Evans, D, Stevenson, A.G, Bulat, J, Ritchie, J.D, (1994) 'United Kingdom offshore regional report: the geology of the central North Sea.' London: HMSO for the British Geological Survey Kulhmann, G., Langereis C.G., Munsterman, D., van Leeuwen, R.-J., Verreussel, R., Meulenkamp, J.E., Wong, Th.E., 2006 'Intergrated chronostratigraphy of the Pliocene-Pliestocene interval and its relation to the regional stratigraphical stages in the Southern North Sea region' Netherlands Journal of Geosciences 85(1), 29-45 Rasmussen, E.A., Vejb?k O.V., Bidstrup, T., Piasecki, S., Dybkj?r, K., 2005 'Late Cenozoic depositional history of the Danish North Sea Basin: implications for the petroleum systems in the Kraka, Halfdan, Siri and Nini fields', Petroleum Geology Conference series 6, 1347-1358 Sejrup, H.P., Aareseth, I., Haflidason, H., 1991 'The Quaternary succession in the northern North Sea' Marine Geology 101 103-111

Active, capable, and potentially active faults - a paleoseismic perspective

USGS Publications Warehouse

Machette, M.N.

2000-01-01

Maps of faults (geologically defined source zones) may portray seismic hazards in a wide range of completeness depending on which types of faults are shown. Three fault terms - active, capable, and potential - are used in a variety of ways for different reasons or applications. Nevertheless, to be useful for seismic-hazards analysis, fault maps should encompass a time interval that includes several earthquake cycles. For example, if the common recurrence in an area is 20,000-50,000 years, then maps should include faults that are 50,000-100,000 years old (two to five typical earthquake cycles), thus allowing for temporal variability in slip rate and recurrence intervals. Conversely, in more active areas such as plate boundaries, maps showing faults that are <10,000 years old should include those with at least 2 to as many as 20 paleoearthquakes. For the International Lithosphere Programs' Task Group II-2 Project on Major Active Faults of the World our maps and database will show five age categories and four slip rate categories that allow one to select differing time spans and activity rates for seismic-hazard analysis depending on tectonic regime. The maps are accompanied by a database that describes evidence for Quaternary faulting, geomorphic expression, and paleoseismic parameters (slip rate, recurrence interval and time of most recent surface faulting). These maps and databases provide an inventory of faults that would be defined as active, capable, and potentially active for seismic-hazard assessments.

Study of Seismogenic Crust In The Eastern Province of Saudi Arabia And Its Relation To The Seismicity of The Ghawar Fields

NASA Astrophysics Data System (ADS)

Mogren, S. M.; Mukhopadhyay, M.

2013-12-01

The Rayn Anticlines (RA) developed in the Eastern Province of Saudi Arabia are truncated by the Abu-Jifan Fault (AJF) to their southeast and by the Wadi-Batin Fault (WBF) to the northwest. This set of anticlines is comprised of six sub-parallel super-giant anticlines, including the Ghawar Anticline (GA). Here we firstly present a revised seismicity map for the Eastern Province on the basis of ';Reviewed ISC Earthquake Catalogue' for the period 1970-2010 that shows the Eastern Province crust is seismogenic down to about 45 km depth while its surface width is 220 km (what is seven times wider than the width of GA). The Saudi Geological Survey (SGS) Earthquake Network Catalogue for Eastern Province shows that characteristic magnitude completeness (Mc), based on the assumption of self-similarity, have detected all local earthquakes above the cut-off magnitude ≥ 2.7. SGS catalogue events demonstrate that the GA is seismically intensely active where 826 events have originated during the period of 2005-10, of maximum magnitude ML 4.24. These events came almost in equal proportions from the Uthmaniyah-Hawaiyah and Haradh production divisions belonging to the central and southern Ghawar oil/gas Fields, where, the seismic zones orient in NE and NW directions respectively. Focal-depth distribution of events along the strike direction of seismic zones follows the ';En Nala axis' in GA and broadly defines an inverted triangular zone extending to crustal depths. Seismic activity below both the production divisions is supposedly triggered by hydrocarbon fluid-extraction activity; although, their root cause is probably due to regional compressive stress operative across RA. Triggered seismicity locally shows better correlation to mutually opposite reverse faults oriented NW and NE transgressing the Haradh and Uthmaniyah-Hawaiyah production divisions under the influence of regional compressive stress oriented N40°E. Some support to this inference comes from mapped surface faults/lineaments, four composite focal mechanism solutions as well as from the subsurface structural sections showing the pattern of basement uplift below GA. 3D computer simulation for seismicity below GA illustrates that some such attendant basement-faults are crust-penetrative. Location map of the study area showing the regularly-spaced, N-trending super-giant anticlines.

Microzonation Mapping Of The Yanbu Industrial City, Western Saudi Arabia: A Multicriteria Decision Analysis Approach

NASA Astrophysics Data System (ADS)

Moustafa, Sayed, Sr.; Alarifi, Nassir S.; Lashin, Aref A.

2016-04-01

Urban areas along the western coast of Saudi Arabia are susceptible to natural disasters and environmental damages due to lack of planning. To produce a site-specific microzonation map of the rapidly growing Yanbu industrial city, spatial distribution of different hazard entities are assessed using the Analytical Hierarchal Process (AHP) together with Geographical Information System (GIS). For this purpose six hazard parameter layers are considered, namely; fundamental frequency, site amplification, soil strength in terms of effective shear-wave velocity, overburden sediment thickness, seismic vulnerability index and peak ground acceleration. The weight and rank values are determined during AHP and are assigned to each layer and its corresponding classes, respectively. An integrated seismic microzonation map was derived using GIS platform. Based on the derived map, the study area is classified into five hazard categories: very low, low, moderate high, and very high. The western and central parts of the study area, as indicated from the derived microzonation map, are categorized as a high hazard zone as compared to other surrounding places. The produced microzonation map of the current study is envisaged as a first-level assessment of the site specific hazards in the Yanbu city area, which can be used as a platform by different stakeholders in any future land-use planning and environmental hazard management.

Regional analysis of distribution of pre and post 2015 Nepal Earthquake landslides

NASA Astrophysics Data System (ADS)

Valagussa, Andrea; Frattini, Paolo; Crosta, Giovanni; Valbuzzi, Elena

2016-04-01

A magnitude 7.8 earthquake struck Nepal on April 25, 2015. Three landslide inventories have been prepared in four districts: Dhading (1885 km2), Sindhupalchok (2488 km2), Rasuwa (1522 km2) and Nuwakot (1194 km2), that are located north of Kathmandu. These inventories extend 14 to 138 km SE from the epicenter of the main shock (April 25, 2015), 4.5 to 143 km NW from the epicenter of the main aftershock (May 12, 2015), and 34 to 136 km from the Main Frontal Thrust. The first inventory is a coseismic and post-seismic landslide inventory based on multi-temporal images (Google Earth, Google Crisis maps, Bing maps), and helicopter-based video. The second one is a pre-event shallow landslide inventory. In these two inventories the most abundant landslide types are: debris flows, shallow translational slides, and rockfalls. The third is a deep seated landslide inventory, in which the most represented landslide types are rock avalanches, slumps, rockslides and deep-seated gravitational slope deformations (DSGSD). All the landslides have been mapped as individual polygons. For the analysis we focus our attention on four districts: First we studied how the landslide frequency density changes as a function of topographic parameters (i.e. slope gradient, slope aspect, and elevation). The analyses have been based on the ASTER Global Digital Elevation Model (ASTER GDEM). For coseismic and post-seismic landslides we observed that the mean slope gradient at which the landslide occurs is higher with respect to the two other inventories (50° and 30/40° respectively). The slope aspect of coseismic and post-seismic landslides is also different, with a larger frequency of landslides towards SW, whereas in pre-event landslides the most common slope aspect is SE. This could be related to the direction of the seismic wave. At least the coseismic and post-seismic landslides occur, in mean, at an elevation lower than the pre-event landslides. We also analyzed the relationship between the landslide frequency density and the lithology in which each landslide occurs to better understand if a particular geological suite is more prone to give landslides, both in seismic and non-seismic conditions. The landslide density for the Deep Seated Landslides and the Pre-Event Shallow landslides does not shows particular changes with the lithology in which the landslide occurred. The Deep Seated Landslides seem to be more abundant in marbles with respect the others lithologies. The pre-event landslides seem to be more abundant in gneiss and shale. Different observations could be done for the coseismic and post-seismic landslides, which show a high value of density (5.13 landslides per km2) for schist, limestone and quartzite. Instead, the granites have a lower number of landslides, as observed for the two other inventories.

Earthquakes in Action: Incorporating Multimedia, Internet Resources, Large-scale Seismic Data, and 3-D Visualizations into Innovative Activities and Research Projects for Today's High School Students

NASA Astrophysics Data System (ADS)

Smith-Konter, B.; Jacobs, A.; Lawrence, K.; Kilb, D.

2006-12-01

The most effective means of communicating science to today's "high-tech" students is through the use of visually attractive and animated lessons, hands-on activities, and interactive Internet-based exercises. To address these needs, we have developed Earthquakes in Action, a summer high school enrichment course offered through the California State Summer School for Mathematics and Science (COSMOS) Program at the University of California, San Diego. The summer course consists of classroom lectures, lab experiments, and a final research project designed to foster geophysical innovations, technological inquiries, and effective scientific communication (http://topex.ucsd.edu/cosmos/earthquakes). Course content includes lessons on plate tectonics, seismic wave behavior, seismometer construction, fault characteristics, California seismicity, global seismic hazards, earthquake stress triggering, tsunami generation, and geodetic measurements of the Earth's crust. Students are introduced to these topics through lectures-made-fun using a range of multimedia, including computer animations, videos, and interactive 3-D visualizations. These lessons are further enforced through both hands-on lab experiments and computer-based exercises. Lab experiments included building hand-held seismometers, simulating the frictional behavior of faults using bricks and sandpaper, simulating tsunami generation in a mini-wave pool, and using the Internet to collect global earthquake data on a daily basis and map earthquake locations using a large classroom map. Students also use Internet resources like Google Earth and UNAVCO/EarthScope's Jules Verne Voyager Jr. interactive mapping tool to study Earth Science on a global scale. All computer-based exercises and experiments developed for Earthquakes in Action have been distributed to teachers participating in the 2006 Earthquake Education Workshop, hosted by the Visualization Center at Scripps Institution of Oceanography (http://siovizcenter.ucsd.edu/workshop). In addition to daily lecture and lab exercises, COSMOS students also conduct a mini-research project of their choice that uses data ranging from the 2004 Parkfield Earthquake, to Southern California seismicity, to global seismicity. Students collect seismic data from the Internet and evaluate earthquake locations, magnitudes, temporal sequence of seismic activity, active fault planes, and plate tectonic boundaries using research quality techniques. Students are given the opportunity to build 3-D visualizations of their research data sets and archive these at the SIO Visualization Center's online library, which is globally accessible to students, teachers, researchers, and the general public (http://www.siovizcenter.ucsd.edu/library.php). These student- generated visualizations have become a practical resource for not only students and teachers, but also geophysical researchers that use the visual objects as research tools to better explore and understand their data. Through Earthquakes in Action, we offer both the tools for scientific exploration and the thrills of scientific discovery, providing students with valuable knowledge, novel research experience, and a unique sense of scientific contribution.

Method for inverting reflection trace data from 3-D and 4-D seismic surveys and identifying subsurface fluid and pathways in and among hydrocarbon reservoirs based on impedance models

DOEpatents

He, W.; Anderson, R.N.

1998-08-25

A method is disclosed for inverting 3-D seismic reflection data obtained from seismic surveys to derive impedance models for a subsurface region, and for inversion of multiple 3-D seismic surveys (i.e., 4-D seismic surveys) of the same subsurface volume, separated in time to allow for dynamic fluid migration, such that small scale structure and regions of fluid and dynamic fluid flow within the subsurface volume being studied can be identified. The method allows for the mapping and quantification of available hydrocarbons within a reservoir and is thus useful for hydrocarbon prospecting and reservoir management. An iterative seismic inversion scheme constrained by actual well log data which uses a time/depth dependent seismic source function is employed to derive impedance models from 3-D and 4-D seismic datasets. The impedance values can be region grown to better isolate the low impedance hydrocarbon bearing regions. Impedance data derived from multiple 3-D seismic surveys of the same volume can be compared to identify regions of dynamic evolution and bypassed pay. Effective Oil Saturation or net oil thickness can also be derived from the impedance data and used for quantitative assessment of prospective drilling targets and reservoir management. 20 figs.

Method for inverting reflection trace data from 3-D and 4-D seismic surveys and identifying subsurface fluid and pathways in and among hydrocarbon reservoirs based on impedance models

DOEpatents

He, Wei; Anderson, Roger N.

1998-01-01

A method is disclosed for inverting 3-D seismic reflection data obtained from seismic surveys to derive impedance models for a subsurface region, and for inversion of multiple 3-D seismic surveys (i.e., 4-D seismic surveys) of the same subsurface volume, separated in time to allow for dynamic fluid migration, such that small scale structure and regions of fluid and dynamic fluid flow within the subsurface volume being studied can be identified. The method allows for the mapping and quantification of available hydrocarbons within a reservoir and is thus useful for hydrocarbon prospecting and reservoir management. An iterative seismic inversion scheme constrained by actual well log data which uses a time/depth dependent seismic source function is employed to derive impedance models from 3-D and 4-D seismic datasets. The impedance values can be region grown to better isolate the low impedance hydrocarbon bearing regions. Impedance data derived from multiple 3-D seismic surveys of the same volume can be compared to identify regions of dynamic evolution and bypassed pay. Effective Oil Saturation or net oil thickness can also be derived from the impedance data and used for quantitative assessment of prospective drilling targets and reservoir management.

Research, methodology, and applications of probabilistic seismic-hazard mapping of the Central and Eastern United States; minutes of a workshop on June 13-14, 2000, at Saint Louis University

USGS Publications Warehouse

Wheeler, Russell L.; Perkins, David M.

2000-01-01

The U.S. Geological Survey (USGS) is updating and revising its 1996 national seismic-hazard maps for release in 2001. Part of this process is the convening of four regional workshops with earth scientists and other users of the maps. The second of these workshops was sponsored by the USGS and the Mid-America Earthquake Center, and was hosted by Saint Louis University on June 13-14, 2000.The workshop concentrated on the central and eastern U.S. (CEUS) east of the Rocky Mountains. The tasks of the workshop were to (1) evaluate new research findings that are relevant to seismic hazard mapping, (2) discuss modifications in the inputs and methodology used in the national maps, (3) discuss concerns by engineers and other users about the scientific input to the maps and the use of the hazard maps in building codes, and (4) identify needed research in the CEUS that can improve the seismic hazard maps and reduce their uncertainties. These minutes summarize the workshop discussions. This is not a transcript; some individual remarks and short discussions of side issues and logistics were omitted. Named speakers were sent a draft of the minutes with a request for corrections of any errors in remarks attributed to them. Nine people returned corrections, amplifications, or approvals of their remarks as reported. The rest of this document consists of the meeting agenda, discussion summaries, and a list of the 60 attendees.

A Geo-referenced 3D model of the Juan de Fuca Slab and associated seismicity

USGS Publications Warehouse

Blair, J.L.; McCrory, P.A.; Oppenheimer, D.H.; Waldhauser, F.

2011-01-01

We present a Geographic Information System (GIS) of a new 3-dimensional (3D) model of the subducted Juan de Fuca Plate beneath western North America and associated seismicity of the Cascadia subduction system. The geo-referenced 3D model was constructed from weighted control points that integrate depth information from hypocenter locations and regional seismic velocity studies. We used the 3D model to differentiate earthquakes that occur above the Juan de Fuca Plate surface from earthquakes that occur below the plate surface. This GIS project of the Cascadia subduction system supersedes the one previously published by McCrory and others (2006). Our new slab model updates the model with new constraints. The most significant updates to the model include: (1) weighted control points to incorporate spatial uncertainty, (2) an additional gridded slab surface based on the Generic Mapping Tools (GMT) Surface program which constructs surfaces based on splines in tension (see expanded description below), (3) double-differenced hypocenter locations in northern California to better constrain slab location there, and (4) revised slab shape based on new hypocenter profiles that incorporate routine depth uncertainties as well as data from new seismic-reflection and seismic-refraction studies. We also provide a 3D fly-through animation of the model for use as a visualization tool.

Topographic Slope as a Proxy for Seismic Site-Conditions (VS30) and Amplification Around the Globe

USGS Publications Warehouse

Allen, Trevor I.; Wald, David J.

2007-01-01

Executive Summary It is well-known that large global earthquakes can have a dramatic effect on local communities and the built environment. Moreover, ground motions amplified by surficial materials can exacerbate the situation, often making the difference between minor and major damage. For a real-time earthquake impact alert system, such as Prompt Assessment of Global Earthquakes for Response (PAGER) (Wald and others, 2006), we seek to rapidly evaluate potential ground shaking in the source region and subsequently provide an estimate of the population exposure to potentially fatal levels of ground shaking in any region of the world. The contribution of surficial geology (particularly soft sediments) to the amplification of ground shaking is an important component in predicting the levels of ground motion observed at any site. Unfortunately, the availability of information regarding seismic siteconditions is only available at a few sites around the globe. Herein, we describe a methodology for deriving maps of seismic site-conditions anywhere in the world using topographic slope as a proxy. Average shear-velocity down to 30 m (or VS30) measurements are correlated against topographic slope to develop two sets of coefficients for predicting VS30: one for active tectonic regions that possess dynamic topographic relief, and one for stable continental regions where changes in topography are more subdued. These coefficients have been applied to the continental United States, in addition to other regions around the world. They are subsequently compared to existing site-condition maps based on geology and observed VS30 measurements, where available. The application of the topographic slope method in regions with abundant VS30 measurements (for example California, Memphis, and Taiwan) indicates that this method provides site condition-maps of similar quality, or in some cases, maps superior to those developed from more traditional techniques. Having a first-order assessment of seismic site-conditions anywhere in the world provides a valuable tool to rapidly estimate ground motions following any global earthquake, the primary motivation for this research. These VS30 maps will enable us to better quantify possible ground shaking and rapidly deliver these predictions to emergency managers and responders. In addition, the VS30 maps for the globe will also have practical applications for numerous related probabilistic- and scenario-based studies. To date, several researchers have requested maps or have used the approach outlined herein for their own applications (for example Cagnan and Kariptas, written commun., 2007; Harmandar and others, 2007). Given that we anticipate a significant demand for these products, we have developed an internet delivery service so that users can download maps and grids of seismic site-conditions for specified regions. To some extent, these grids can also be customized by the user if they disagree with the predefined correlations derived using the methodologies described within this report. Finally, this report represents a more comprehensive account of this technique and provides a more fully illustrated global description of results than that given in Wald and Allen (2007), which has been accepted for publication in the Bulletin of the Seismological Society of America.

Terrain classification and land hazard mapping in Kalsi-Chakrata area (Garhwal Himalaya), India

NASA Astrophysics Data System (ADS)

Choubey, Vishnu D.; Litoria, Pradeep K.

Terrain classification and land system mapping of a part of the Garhwal Himalaya (India) have been used to provide a base map for land hazard evaluation, with special reference to landslides and other mass movements. The study was based on MSS images, aerial photographs and 1:50,000 scale maps, followed by detailed field-work. The area is composed of two groups of rocks: well exposed sedimentary Precambrian formations in the Himalayan Main Boundary Thrust Belt and the Tertiary molasse deposits of the Siwaliks. Major tectonic boundaries were taken as the natural boundaries of land systems. A physiographic terrain classification included slope category, forest cover, occurrence of landslides, seismicity and tectonic activity in the area.

Study on Seismicity of Sino-Mongolia Arc Areas

NASA Astrophysics Data System (ADS)

Xu, Guangyin; Wang, Suyun

2016-04-01

Using the earthquake catalogue from China, Mongolia and the global catalogue, the uniform catalogue of North China, Mongolia and adjacent areas, which is within the region 80-130°E, 40-55°N, has been established by Institute of Geophysics, China Earthquake Administration and Research Center of Astronomy and Geophysics, Mongolian Academy of Science for the seismic hazard analysis and seismic zoning map of Mongolia according to the following principles. 1) Earthquakes, which just exist in one catalogue, need to be verified further. If the earthquakes occurred in the country where the catalog comes from, then they will be adopted. If not, it should be checked with other more data. 2) The events that come from the three data sources have be checked and verified as followings. (1) The parameters of earthquakes that occurred in China will be taken from China catalog. (2)The parameters of earthquakes that occurred in Mongolia will be taken from Mongolia catalog. (3) The parameters of earthquakes that occurred in the adjacent areas will be taken from the global catalog by Song et al. According to the uniform catalogue, the seismicity of the North China, Mongolia and adjacent areas is analyzed, and the conclusions as followings are made. 1) The epicenter map can be roughly divided into two parts, bounded by the longitude line 105°E , in accordance with the "North-South Seismic Belt" of China. The seismicity is in a high level with many strong earthquakes in the west and is in a low level with little strong events in the east. 2) Most earthquakes are shallow-focus events, but there are also several middle or deep-focus events in the study area. 3) Earthquakes with magnitude greater than 5 are basically complete since 1450 A.D., and the seismicity of the study areas is in a high level since 1700 A. 4) Two seismic belts, Altay seismic belt and Bolnay-Baikal seismic belt, are determined according to the epicenters and tectonics. 5) The b-values of magnitude - frequency relationship for the whole areas are between 0.6 and 0.7 based on the uniform catalogue, 0.677 for the Altay seismic belt and 0.699 for the Bolnay-Baikal seismic belt. KEY WORDS：Earthquake Catalogue, Seismicity, North China, Mongolia

Progress in the development of shallow-water mapping systems

USGS Publications Warehouse

Bergeron, E.; Worley, C.R.; O'Brien, T.

2007-01-01

The USGS (US Geological Survey) Coastal and Marine Geology has deployed an advance autonomous shallow-draft robotic vehicle, Iris, for shallow-water mapping in Apalachicola Bay, Florida. The vehicle incorporates a side scan sonar system, seismic-reflection profiler, single-beam echosounder, and global positioning system (GPS) navigation. It is equipped with an onboard microprocessor-based motor controller, delivering signals for speed and steering to hull-mounted brushless direct-current thrusters. An onboard motion sensor in the Sea Robotics vehicle control system enclosure has been integrated in the vehicle to measure the vehicle heave, pitch, roll, and heading. Three water-tight enclosures are mounted along the vehicle axis for the Edgetech computer and electronics system including the Sea Robotics computer, a control and wireless communications system, and a Thales ZXW real-time kinematic (RTK) GPS receiver. The vehicle has resulted in producing high-quality seismic reflection and side scan sonar data, which will help in developing the baseline oyster habitat maps.

Seismic maps foster landmark legislation

USGS Publications Warehouse

Borcherdt, Roger D.; Brown, Robert B.; Page, Robert A.; Wentworth, Carl M.; Hendley, James W.

1995-01-01

When a powerful earthquake strikes an urban region, damage concentrates not only near the quake's source. Damage can also occur many miles from the source in areas of soft ground. In recent years, scientists have developed ways to identify and map these areas of high seismic hazard. This advance has spurred pioneering legislation to reduce earthquake losses in areas of greatest hazard.

High-Resolution Seismic-Reflection and Marine Magnetic Data Along the Hosgri Fault Zone, Central California

USGS Publications Warehouse

Sliter, Ray W.; Triezenberg, Peter J.; Hart, Patrick E.; Watt, Janet T.; Johnson, Samuel Y.; Scheirer, Daniel S.

2009-01-01

The U.S. Geological Survey (USGS) collected high-resolution shallow seismic-reflection and marine magnetic data in June 2008 in the offshore areas between the towns of Cayucos and Pismo Beach, Calif., from the nearshore (~6-m depth) to just west of the Hosgri Fault Zone (~200-m depth). These data are in support of the California State Waters Mapping Program and the Cooperative Research and Development Agreement (CRADA) between the Pacific Gas & Electric Co. and the U.S. Geological Survey. Seismic-reflection and marine magnetic data were acquired aboard the R/V Parke Snavely, using a SIG 2Mille minisparker seismic source and a Geometrics G882 cesium-vapor marine magnetometer. More than 550 km of seismic and marine magnetic data was collected simultaneously along shore-perpendicular transects spaced 800 m apart, with an additional 220 km of marine magnetometer data collected across the Hosgri Fault Zone, resulting in spacing locally as smallas 400 m. This report includes maps of the seismic-survey sections, linked to Google Earth software, and digital data files showing images of each transect in SEG-Y, JPEG, and TIFF formats, as well as preliminary gridded marine-magnetic-anomaly and residual-magnetic-anomaly (shallow magnetic source) maps.

Global Seismicity: Three New Maps Compiled with Geographic Information Systems

NASA Technical Reports Server (NTRS)

Lowman, Paul D., Jr.; Montgomery, Brian C.

1996-01-01

This paper presents three new maps of global seismicity compiled from NOAA digital data, covering the interval 1963-1998, with three different magnitude ranges (mb): greater than 3.5, less than 3.5, and all detectable magnitudes. A commercially available geographic information system (GIS) was used as the database manager. Epicenter locations were acquired from a CD-ROM supplied by the National Geophysical Data Center. A methodology is presented that can be followed by general users. The implications of the maps are discussed, including the limitations of conventional plate models, and the different tectonic behavior of continental vs. oceanic lithosphere. Several little-known areas of intraplate or passive margin seismicity are also discussed, possibly expressing horizontal compression generated by ridge push.

Documentation for the 2014 update of the United States national seismic hazard maps

USGS Publications Warehouse

Petersen, Mark D.; Moschetti, Morgan P.; Powers, Peter M.; Mueller, Charles S.; Haller, Kathleen M.; Frankel, Arthur D.; Zeng, Yuehua; Rezaeian, Sanaz; Harmsen, Stephen C.; Boyd, Oliver S.; Field, Edward; Chen, Rui; Rukstales, Kenneth S.; Luco, Nico; Wheeler, Russell L.; Williams, Robert A.; Olsen, Anna H.

2014-01-01

The national seismic hazard maps for the conterminous United States have been updated to account for new methods, models, and data that have been obtained since the 2008 maps were released (Petersen and others, 2008). The input models are improved from those implemented in 2008 by using new ground motion models that have incorporated about twice as many earthquake strong ground shaking data and by incorporating many additional scientific studies that indicate broader ranges of earthquake source and ground motion models. These time-independent maps are shown for 2-percent and 10-percent probability of exceedance in 50 years for peak horizontal ground acceleration as well as 5-hertz and 1-hertz spectral accelerations with 5-percent damping on a uniform firm rock site condition (760 meters per second shear wave velocity in the upper 30 m, VS30). In this report, the 2014 updated maps are compared with the 2008 version of the maps and indicate changes of plus or minus 20 percent over wide areas, with larger changes locally, caused by the modifications to the seismic source and ground motion inputs.

Seismic hazard of the Kivu rift (western branch, East African Rift system): new neotectonic map and seismotectonic zonation model

NASA Astrophysics Data System (ADS)

Delvaux, Damien; Mulumba, Jean-Luc; Sebagenzi Mwene Ntabwoba, Stanislas; Fiama Bondo, Silvanos; Kervyn, François; Havenith, Hans-Balder

2017-04-01

The first detailed probabilistic seismic hazard assessment has been performed for the Kivu and northern Tanganyika rift region in Central Africa. This region, which forms the central part of the Western Rift Branch, is one of the most seismically active part of the East African rift system. It was already integrated in large scale seismic hazard assessments, but here we defined a finer zonation model with 7 different zones representing the lateral variation of the geological and geophysical setting across the region. In order to build the new zonation model, we compiled homogeneous cross-border geological, neotectonic and sismotectonic maps over the central part of East D.R. Congo, SW Uganda, Rwanda, Burundi and NW Tanzania and defined a new neotectonic sheme. The seismic risk assessment is based on a new earthquake catalogue, compiled on the basis of various local and global earthquake catalogues. The use of macroseismic epicenters determined from felt earthquakes allowed to extend the time-range back to the beginning of the 20th century, spanning 126 years, with 1068 events. The magnitudes have been homogenized to Mw and aftershocks removed. From this initial catalogue, a catalogue of 359 events from 1956 to 2015 and with M > 4.4 has been extracted for the seismic hazard assessment. The seismotectonic zonation includes 7 seismic source areas that have been defined on the basis of the regional geological structure, neotectonic fault systems, basin architecture and distribution of thermal springs and earthquake epicenters. The Gutenberg-Richter seismic hazard parameters were determined using both the least square linear fit and the maximum likelihood method (Kijko & Smit aue program). Seismic hazard maps have been computed with the Crisis 2012 software using 3 different attenuation laws. We obtained higher PGA values (475 years return period) for the Kivu rift region than the previous estimates (Delvaux et al., 2016). They vary laterally in function of the tectonic setting, with the lowest value in the volcanically active Virunga - Rutshuru zone, highest in the currently non-volcanic parts of Lake Kivu, Rusizi valley and North Tanganyika rift zone, and intermediate in the regions flanking the axial rift zone. Those are to be considered as preliminary values, as there are a number of important uncertainties such as the heterogeneity and relatively short duration of the instrumental seismic catalogue used (60 years), the absence of locally derived attenuation laws and thus the choice of the attenuation laws used, and the seismic zonation scheme. Delvaux, D. et al., 2016. Journal of African Earth Sciences, doi: 10.1016/j.jafrearsci.2016.10.004.

A global tectonic activity map with orbital photographic supplement

NASA Technical Reports Server (NTRS)

Lowman, P. D., Jr.

1981-01-01

A three part map showing equatorial and polar regions was compiled showing tectonic and volcanic activity of the past one million years, including the present. Features shown include actively spreading ridges, spreading rates, major active faults, subduction zones, well defined plates, and volcanic areas active within the past one million years. Activity within this period was inferred from seismicity (instrumental and historic), physiography, and published literature. The tectonic activity map was used for planning global geodetic programs of satellite laser ranging and very long base line interferometry and for geologic education.

3-D seismic data for field development: Landslide field case study

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

Raeuchle, S.K.; Carr, T.R.; Tucker, R.D.

1990-05-01

The Landslide field is located on the extreme southern flank of the San Joaquin basin, approximately 25 mi south of Bakersfield, California. The field, discovered in 1985, has produced in excess 9 million bbl of oil with an estimated ultimate recovery of more than 13 MMBO. The Miocene Stevens sands, which form the reservoir units at Landslide field, are interpreted as a series of constructional submarine fan deposits. Deposition of the fans was controlled by paleotopography with an abrupt updip pinch-out of the sands to the southwest. The three-dimensional seismic data over the field was used to locate the bottommore » hole of the landslide 22X-30 development well as close to this abrupt updip pinchout as possible in order to maximize oil recovery. A location was selected two traces (330 ft) from the updip pinch-out as mapped on the seismic data. The well was successfully drilled during 1989, encountering 150 ft of net sand with initial production in excess of 1,500 bbl of oil/day. A pressure buildup test indicates the presence of a boundary approximately 200 ft from the well bore. This boundary is interpreted as the updip pinchout of the Stevens sands against the paleohigh. Based on examination of changes in amplitude, the absence or presence of reservoir-quality sand can be mapped across the paleohighs. Application of three-dimensional seismic data, integration with well data, and in particular reconstruction cuts tied closely to existing wells can be used to map the ultimate extent of the field and contribute to efficient development.« less

The Use of GIS for the Application of the Phenomenological Approach to the Seismic Risk Analysis: the Case of the Italian Fortified Architecture

NASA Astrophysics Data System (ADS)

Lenticchia, E.; Coïsson, E.

2017-05-01

The present paper proposes the use of GIS for the application of the so-called phenomenological approach to the analysis of the seismic behaviour of historical buildings. This approach is based on the awareness that the different masonry building typologies are characterized by different, recurring vulnerabilities. Thus, the observation and classification of the real damage is seen as the first step for recognizing and classifying these vulnerabilities, in order to plan focused preventive interventions. For these purposes, the GIS has proven to be a powerful instrument to collect and manage this type of information on a large number of cases. This paper specifically focuses on the application of the phenomenological approach to the analysis of the seismic behaviour of fortified buildings, including castles, fortresses, citadels, and all the typical historical constructions characterized by the presence of massive towers and defensive walls. The main earthquakes which struck Italy in the last 40 years (up to the recent Central Italy seismic swarm) were taken into consideration and described by means of shake maps. A previously published work has been continued with the addition of new data and some improvements, including a specific symbology for the description of building typologies and conservation status on the maps, the indications of damage levels and the comparison between shake maps in terms of pga and in terms of pseudo-acceleration. The increase in knowledge obtained and the broader frame given by the analysis of the data are here directed to the primary aim of cultural heritage preservation.

Program and plans of the U.S. Geological Survey for producing information needed in National Seismic hazards and risk assessment, fiscal years 1980-84

USGS Publications Warehouse

Hays, Walter W.

1979-01-01

In accordance with the provisions of the Earthquake Hazards Reduction Act of 1977 (Public Law 95-124), the U.S. Geological Survey has developed comprehensive plans for producing information needed to assess seismic hazards and risk on a national scale in fiscal years 1980-84. These plans are based on a review of the needs of Federal Government agencies, State and local government agencies, engineers and scientists engaged in consulting and research, professional organizations and societies, model code groups, and others. The Earthquake Hazards Reduction Act provided an unprecedented opportunity for participation in a national program by representatives of State and local governments, business and industry, the design professions, and the research community. The USGS and the NSF (National Science Foundation) have major roles in the national program. The ultimate goal of the program is to reduce losses from earthquakes. Implementation of USGS research in the Earthquake Hazards Reduction Program requires the close coordination of responsibility between Federal, State and local governments. The projected research plan in national seismic hazards and risk for fiscal years 1980-84 will be accomplished by USGS and non-USGS scientists and engineers. The latter group will participate through grants and contracts. The research plan calls for (1) national maps based on existing methods, (2) improved definition of earthquake source zones nationwide, (3) development of improved methodology, (4) regional maps based on the improved methodology, and (5) post-earthquake investigations. Maps and reports designed to meet the needs, priorities, concerns, and recommendations of various user groups will be the products of this research and provide the technical basis for improved implementation.

Thermal structure of Sikhote Alin and adjacent areas based on spectral analysis of the anomalous magnetic field

NASA Astrophysics Data System (ADS)

Didenko, A. N.; Nosyrev, M. Yu.; Shevchenko, B. F.; Gilmanova, G. Z.

2017-11-01

The depth of the base of the magnetoactive layer and the geothermal gradient in the Sikhote Alin crust are estimated based on a method determining the Curie depth point of magnetoactive masses by using spectral analysis of the anomalous magnetic field. A detailed map of the geothermal gradient is constructed for the first time for the Sikhote Alin and adjacent areas of the Central Asian belt. Analysis of this map shows that the zones with a higher geothermal gradient geographically fit the areas with a higher level of seismicity.

Internet-Based Solutions for a Secure and Efficient Seismic Network

NASA Astrophysics Data System (ADS)

Bhadha, R.; Black, M.; Bruton, C.; Hauksson, E.; Stubailo, I.; Watkins, M.; Alvarez, M.; Thomas, V.

2017-12-01

The Southern California Seismic Network (SCSN), operated by Caltech and USGS, leverages modern Internet-based computing technologies to provide timely earthquake early warning for damage reduction, event notification, ShakeMap, and other data products. Here we present recent and ongoing innovations in telemetry, security, cloud computing, virtualization, and data analysis that have allowed us to develop a network that runs securely and efficiently.Earthquake early warning systems must process seismic data within seconds of being recorded, and SCSN maintains a robust and resilient network of more than 350 digital strong motion and broadband seismic stations to achieve this goal. We have continued to improve the path diversity and fault tolerance within our network, and have also developed new tools for latency monitoring and archiving.Cyberattacks are in the news almost daily, and with most of our seismic data streams running over the Internet, it is only a matter of time before SCSN is targeted. To ensure system integrity and availability across our network, we have implemented strong security, including encryption and Virtual Private Networks (VPNs).SCSN operates its own data center at Caltech, but we have also installed real-time servers on Amazon Web Services (AWS), to provide an additional level of redundancy, and eventually to allow full off-site operations continuity for our network. Our AWS systems receive data from Caltech-based import servers and directly from field locations, and are able to process the seismic data, calculate earthquake locations and magnitudes, and distribute earthquake alerts, directly from the cloud.We have also begun a virtualization project at our Caltech data center, allowing us to serve data from Virtual Machines (VMs), making efficient use of high-performance hardware and increasing flexibility and scalability of our data processing systems.Finally, we have developed new monitoring of station average noise levels at most stations. Noise monitoring is effective at identifying anthropogenic noise sources and malfunctioning acquisition equipment. We have built a dynamic display of results with sorting and mapping capabilities that allow us to quickly identify problematic sites and areas with elevated noise.

Mass-transport deposits controlling fault propagation, reactivation and structural decoupling on continental margins (Espírito Santo Basin, SE Brazil)

NASA Astrophysics Data System (ADS)

Omosanya, Kamal'deen O.; Alves, Tiago M.

2014-07-01

This work uses high-quality 3D seismic data to assess the importance of mass-transport deposits (MTDs) as markers of fault propagation. We mapped three distinct MTDs and several fault families on the continental slope of Espírito Santo, SE Brazil. Fault mapping was based on seismic attributes such as seismic coherence and structural smoothing, and was further completed using ant tracking algorithms. Genetically related fault families were analysed in terms of their throw-depth (t-z) and throw-distance (t-x) gradient curves. A key result in this paper is that vertical fault propagation can be hindered by MTDs, as demonstrated for Eocene to Early Miocene faults in parts of the study area. Throw-depth variations in faults affected by MTDs are associated with: a) lithologic controls resulting from the presence of MTDs, b) local fault segmentation and c) reactivation by dip linkage. Based on their orientation and degree of interaction with MTDs, interpreted faults can be classified as decoupled and non-decoupled. Importantly, faults decoupled by MTDs have quasi-elliptical t-x profiles and show smaller cumulative throw values and fault propagation rates when compared to their non-decoupled counterparts. Recurrent MTDs can therefore be used as markers to estimate structural decoupling between distinct fault families.

Adding seismic broadband analysis to characterize Andean backarc seismicity in Argentina

NASA Astrophysics Data System (ADS)

Alvarado, P.; Giuliano, A.; Beck, S.; Zandt, G.

2007-05-01

Characterization of the highly seismically active Andean backarc is crucial for assessment of earthquake hazards in western Argentina. Moderate-to-large crustal earthquakes have caused several deaths, damage and drastic economic consequences in Argentinean history. We have studied the Andean backarc crust between 30°S and 36°S using seismic broadband data available from a previous ("the CHARGE") IRIS-PASSCAL experiment. We collected more than 12 terabytes of continuous seismic data from 22 broadband instruments deployed across Chile and Argentina during 1.5 years. Using free software we modeled full regional broadband waveforms and obtained seismic moment tensor inversions of crustal earthquakes testing for the best focal depth for each event. We also mapped differences in the Andean backarc crustal structure and found a clear correlation with different types of crustal seismicity (i.e. focal depths, focal mechanisms, magnitudes and frequencies of occurrence) and previously mapped terrane boundaries. We now plan to use the same methodology to study other regions in Argentina using near-real time broadband data available from the national seismic (INPRES) network and global seismic networks operating in the region. We will re-design the national seismic network to optimize short-period and broadband seismic station coverage for different network purposes. This work is an international effort that involves researchers and students from universities and national government agencies with the goal of providing more information about earthquake hazards in western Argentina.

Using Earthquake Analysis to Expand the Oklahoma Fault Database

NASA Astrophysics Data System (ADS)

Chang, J. C.; Evans, S. C.; Walter, J. I.

2017-12-01

The Oklahoma Geological Survey (OGS) is compiling a comprehensive Oklahoma Fault Database (OFD), which includes faults mapped in OGS publications, university thesis maps, and industry-contributed shapefiles. The OFD includes nearly 20,000 fault segments, but the work is far from complete. The OGS plans on incorporating other sources of data into the OFD, such as new faults from earthquake sequence analyses, geologic field mapping, active-source seismic surveys, and potential fields modeling. A comparison of Oklahoma seismicity and the OFD reveals that earthquakes in the state appear to nucleate on mostly unmapped or unknown faults. Here, we present faults derived from earthquake sequence analyses. From 2015 to present, there has been a five-fold increase in realtime seismic stations in Oklahoma, which has greatly expanded and densified the state's seismic network. The current seismic network not only improves our threshold for locating weaker earthquakes, but also allows us to better constrain focal plane solutions (FPS) from first motion analyses. Using nodal planes from the FPS, HypoDD relocation, and historic seismic data, we can elucidate these previously unmapped seismogenic faults. As the OFD is a primary resource for various scientific investigations, the inclusion of seismogenic faults improves further derivative studies, particularly with respect to seismic hazards. Our primal focus is on four areas of interest, which have had M5+ earthquakes in recent Oklahoma history: Pawnee (M5.8), Prague (M5.7), Fairview (M5.1), and Cushing (M5.0). Subsequent areas of interest will include seismically active data-rich areas, such as the central and northcentral parts of the state.

Map of Pseudo-F-statistics of seismic noise parameters as an indicator of current seismic danger in Japan

NASA Astrophysics Data System (ADS)

Lyubushin, Alexey

2016-04-01

The problem of estimate of current seismic danger based on monitoring of seismic noise properties from broadband seismic network F-net in Japan (84 stations) is considered. Variations of the following seismic noise parameters are analyzed: multifractal singularity spectrum support width, generalized Hurst exponent, minimum Hölder-Lipschitz exponent and minimum normalized entropy of squared orthogonal wavelet coefficients. These parameters are estimated within adjacent time windows of the length 1 day for seismic noise waveforms from each station. Calculating daily median values of these parameters by all stations provides 4-dimensional time series which describes integral properties of the seismic noise in the region covered by the network. Cluster analysis is applied to the sequence of clouds of 4-dimensional vectors within moving time window of the length 365 days with mutual shift 3 days starting from the beginning of 1997 up to the current time. The purpose of the cluster analysis is to find the best number of clusters (BNC) from probe numbers which are varying from 1 up to the maximum value 40. The BNC is found from the maximum of pseudo-F-statistics (PFS). A 2D map could be created which presents dependence of PFS on the tested probe number of clusters and the right-hand end of moving time window which is rather similar to usual spectral time-frequency diagrams. In the paper [1] it was shown that the BNC before Tohoku mega-earthquake on March 11, 2011, has strongly chaotic regime with jumps from minimum up to maximum values in the time interval 1 year before the event and this time intervals was characterized by high PFS values. The PFS-map is proposed as the method for extracting time intervals with high current seismic danger. The next danger time interval after Tohoku mega-EQ began at the end of 2012 and was finished at the middle of 2013. Starting from middle of 2015 the high PFS values and chaotic regime of BNC variations were returned. This could be interpreted as the increasing of the danger of the next mega-EQ in Japan in the region of Nankai Trough [1] at the first half of 2016. References 1. Lyubushin, A., 2013. How soon would the next mega-earthquake occur in Japan? // Natural Science, 5 (8A1), 1-7. http://dx.doi.org/10.4236/ns.2013.58A1001

Improving fault image by determination of optimum seismic survey parameters using ray-based modeling

NASA Astrophysics Data System (ADS)

Saffarzadeh, Sadegh; Javaherian, Abdolrahim; Hasani, Hossein; Talebi, Mohammad Ali

2018-06-01

In complex structures such as faults, salt domes and reefs, specifying the survey parameters is more challenging and critical owing to the complicated wave field behavior involved in such structures. In the petroleum industry, detecting faults has become crucial for reservoir potential where faults can act as traps for hydrocarbon. In this regard, seismic survey modeling is employed to construct a model close to the real structure, and obtain very realistic synthetic seismic data. Seismic modeling software, the velocity model and parameters pre-determined by conventional methods enable a seismic survey designer to run a shot-by-shot virtual survey operation. A reliable velocity model of structures can be constructed by integrating the 2D seismic data, geological reports and the well information. The effects of various survey designs can be investigated by the analysis of illumination maps and flower plots. Also, seismic processing of the synthetic data output can describe the target image using different survey parameters. Therefore, seismic modeling is one of the most economical ways to establish and test the optimum acquisition parameters to obtain the best image when dealing with complex geological structures. The primary objective of this study is to design a proper 3D seismic survey orientation to achieve fault zone structures through ray-tracing seismic modeling. The results prove that a seismic survey designer can enhance the image of fault planes in a seismic section by utilizing the proposed modeling and processing approach.

3-D Velocity Model of the Coachella Valley, Southern California Based on Explosive Shots from the Salton Seismic Imaging Project

NASA Astrophysics Data System (ADS)

Persaud, P.; Stock, J. M.; Fuis, G. S.; Hole, J. A.; Goldman, M.; Scheirer, D. S.

2014-12-01

We have analyzed explosive shot data from the 2011 Salton Seismic Imaging Project (SSIP) across a 2-D seismic array and 5 profiles in the Coachella Valley to produce a 3-D P-wave velocity model that will be used in calculations of strong ground shaking. Accurate maps of seismicity and active faults rely both on detailed geological field mapping and a suitable velocity model to accurately locate earthquakes. Adjoint tomography of an older version of the SCEC 3-D velocity model shows that crustal heterogeneities strongly influence seismic wave propagation from moderate earthquakes (Tape et al., 2010). These authors improve the crustal model and subsequently simulate the details of ground motion at periods of 2 s and longer for hundreds of ray paths. Even with improvements such as the above, the current SCEC velocity model for the Salton Trough does not provide a match of the timing or waveforms of the horizontal S-wave motions, which Wei et al. (2013) interpret as caused by inaccuracies in the shallow velocity structure. They effectively demonstrate that the inclusion of shallow basin structure improves the fit in both travel times and waveforms. Our velocity model benefits from the inclusion of known location and times of a subset of 126 shots detonated over a 3-week period during the SSIP. This results in an improved velocity model particularly in the shallow crust. In addition, one of the main challenges in developing 3-D velocity models is an uneven stations-source distribution. To better overcome this challenge, we also include the first arrival times of the SSIP shots at the more widely spaced Southern California Seismic Network (SCSN) in our inversion, since the layout of the SSIP is complementary to the SCSN. References: Tape, C., et al., 2010, Seismic tomography of the Southern California crust based on spectral-element and adjoint methods: Geophysical Journal International, v. 180, no. 1, p. 433-462. Wei, S., et al., 2013, Complementary slip distributions of the largest earthquakes in the 2012 Brawley swarm, Imperial Valley, California: Geophysical Research Letters, v. 40, no. 5, p. 847-852.

A new tool for rapid and automatic estimation of earthquake source parameters and generation of seismic bulletins

NASA Astrophysics Data System (ADS)

Zollo, Aldo

2016-04-01

RISS S.r.l. is a Spin-off company recently born from the initiative of the research group constituting the Seismology Laboratory of the Department of Physics of the University of Naples Federico II. RISS is an innovative start-up, based on the decade-long experience in earthquake monitoring systems and seismic data analysis of its members and has the major goal to transform the most recent innovations of the scientific research into technological products and prototypes. With this aim, RISS has recently started the development of a new software, which is an elegant solution to manage and analyse seismic data and to create automatic earthquake bulletins. The software has been initially developed to manage data recorded at the ISNet network (Irpinia Seismic Network), which is a network of seismic stations deployed in Southern Apennines along the active fault system responsible for the 1980, November 23, MS 6.9 Irpinia earthquake. The software, however, is fully exportable and can be used to manage data from different networks, with any kind of station geometry or network configuration and is able to provide reliable estimates of earthquake source parameters, whichever is the background seismicity level of the area of interest. Here we present the real-time automated procedures and the analyses performed by the software package, which is essentially a chain of different modules, each of them aimed at the automatic computation of a specific source parameter. The P-wave arrival times are first detected on the real-time streaming of data and then the software performs the phase association and earthquake binding. As soon as an event is automatically detected by the binder, the earthquake location coordinates and the origin time are rapidly estimated, using a probabilistic, non-linear, exploration algorithm. Then, the software is able to automatically provide three different magnitude estimates. First, the local magnitude (Ml) is computed, using the peak-to-peak amplitude of the equivalent Wood-Anderson displacement recordings. The moment magnitude (Mw) is then estimated from the inversion of displacement spectra. The duration magnitude (Md) is rapidly computed, based on a simple and automatic measurement of the seismic wave coda duration. Starting from the magnitude estimates, other relevant pieces of information are also computed, such as the corner frequency, the seismic moment, the source radius and the seismic energy. The ground-shaking maps on a Google map are produced, for peak ground acceleration (PGA), peak ground velocity (PGV) and instrumental intensity (in SHAKEMAP® format), or a plot of the measured peak ground values. Furthermore, based on a specific decisional scheme, the automatic discrimination between local earthquakes occurred within the network and regional/teleseismic events occurred outside the network is performed. Finally, for largest events, if a consistent number of P-wave polarity reading are available, the focal mechanism is also computed. For each event, all of the available pieces of information are stored in a local database and the results of the automatic analyses are published on an interactive web page. "The Bulletin" shows a map with event location and stations, as well as a table listing all the events, with the associated parameters. The catalogue fields are the event ID, the origin date and time, latitude, longitude, depth, Ml, Mw, Md, the number of triggered stations, the S-displacement spectra, and shaking maps. Some of these entries also provide additional information, such as the focal mechanism (when available). The picked traces are uploaded in the database and from the web interface of the Bulletin the traces can be download for more specific analysis. This innovative software represents a smart solution, with a friendly and interactive interface, for high-level analysis of seismic data analysis and it may represent a relevant tool not only for seismologists, but also for non-expert external users who are interested in the seismological data. The software is a valid tool for the automatic analysis of the background seismicity at different time scales and can be a relevant tool for the monitoring of both natural and induced seismicity.

Stress-based aftershock forecasts made within 24h post mainshock: Expected north San Francisco Bay area seismicity changes after the 2014M=6.0 West Napa earthquake

USGS Publications Warehouse

Parsons, Thomas E.; Segou, Margaret; Sevilgen, Volkan; Milner, Kevin; Field, Edward; Toda, Shinji; Stein, Ross S.

2014-01-01

We calculate stress changes resulting from the M= 6.0 West Napa earthquake on north San Francisco Bay area faults. The earthquake ruptured within a series of long faults that pose significant hazard to the Bay area, and we are thus concerned with potential increases in the probability of a large earthquake through stress transfer. We conduct this exercise as a prospective test because the skill of stress-based aftershock forecasting methodology is inconclusive. We apply three methods: (1) generalized mapping of regional Coulomb stress change, (2) stress changes resolved on Uniform California Earthquake Rupture Forecast faults, and (3) a mapped rate/state aftershock forecast. All calculations were completed within 24 h after the main shock and were made without benefit of known aftershocks, which will be used to evaluative the prospective forecast. All methods suggest that we should expect heightened seismicity on parts of the southern Rodgers Creek, northern Hayward, and Green Valley faults.

Stress-based aftershock forecasts made within 24 h postmain shock: Expected north San Francisco Bay area seismicity changes after the 2014 M = 6.0 West Napa earthquake

NASA Astrophysics Data System (ADS)

Parsons, Tom; Segou, Margaret; Sevilgen, Volkan; Milner, Kevin; Field, Edward; Toda, Shinji; Stein, Ross S.

2014-12-01

We calculate stress changes resulting from the M = 6.0 West Napa earthquake on north San Francisco Bay area faults. The earthquake ruptured within a series of long faults that pose significant hazard to the Bay area, and we are thus concerned with potential increases in the probability of a large earthquake through stress transfer. We conduct this exercise as a prospective test because the skill of stress-based aftershock forecasting methodology is inconclusive. We apply three methods: (1) generalized mapping of regional Coulomb stress change, (2) stress changes resolved on Uniform California Earthquake Rupture Forecast faults, and (3) a mapped rate/state aftershock forecast. All calculations were completed within 24 h after the main shock and were made without benefit of known aftershocks, which will be used to evaluative the prospective forecast. All methods suggest that we should expect heightened seismicity on parts of the southern Rodgers Creek, northern Hayward, and Green Valley faults.

Seismic microzoning in the metropolitan area of Port - au-Prince - complexity of the subsoil

NASA Astrophysics Data System (ADS)

Gilles, R.; Bertil, D.; Belvaux, M.; Roulle, A.; Noury, G.; Prepetit, C.; Jean-Philippe, J.

2013-12-01

The magnitude 7.3 earthquake that struck Haiti in January 12, 2010 has caused a lot of damages in surrounding areas epicenter. These damages are due to a lack of knowledge of the Haitian subsoil. To overcome this problem, the LNBTP, the BME and BRGM have agreed to implement a project of seismic microzonation of the metropolitan area of Port-au-Prince which is financed by the Fund for the reconstruction of the country. The seismic microzonation is an important tool for knowledge of seismic risk. It is based on a collection of geological, geotechnical, geophysical and measures and recognition and the campaign of numerous sites. It describes a class of specific soils with associated spectral response. The objective of the microzoning is to identify and map the homogeneous zones of lithology, topography, liquefaction and ground movements. The zoning of lithological sites effect is to identify and map areas with geological and geomechanical consistent and homogeneous seismic response; the objective is to provide, in each area, seismic movements adapted to the ground. This zoning is done in about five steps: 1- Cross-analysis of geological, geotechnical and geophysical information; 2- Such information comprise the existing data collected and the data acquired during the project; 3- Identification of homogeneous areas. 4- Definition of one or more columns of representative soils associated with each zone; 5 - Possible consolidation of area to get the final seismic zoning. 27 zones types were considered for the study of sites effects after the analysis of all geological, geotechnical and geophysical data. For example, for the formation of Delmas, there are 5 areas with soil classes ranging from D to C. Soil columns described in the metropolitan area of Port-au-Prince are processed with the CyberQuake software, which is developed at the BRGM by Modaressi et al. in 1997, to calculate their response to seismic rock solicitation. The seismic motion is determined by 4 accelerograms (2 real and 2 altered real) having a spectral response close to the spectrum of acceleration to the rock. In sum, the seismic microzoning presents a better perspective for the preparation of the plan for the prevention of seismic risk (PPRS) and for the establishment of seismic rules in the metropolitan area of Port-au-Prince.

Preliminary Earthquake Hazard Map of Afghanistan

USGS Publications Warehouse

Boyd, Oliver S.; Mueller, Charles S.; Rukstales, Kenneth S.

2007-01-01

Introduction Earthquakes represent a serious threat to the people and institutions of Afghanistan. As part of a United States Agency for International Development (USAID) effort to assess the resource potential and seismic hazards of Afghanistan, the Seismic Hazard Mapping group of the United States Geological Survey (USGS) has prepared a series of probabilistic seismic hazard maps that help quantify the expected frequency and strength of ground shaking nationwide. To construct the maps, we do a complete hazard analysis for each of ~35,000 sites in the study area. We use a probabilistic methodology that accounts for all potential seismic sources and their rates of earthquake activity, and we incorporate modeling uncertainty by using logic trees for source and ground-motion parameters. See the Appendix for an explanation of probabilistic seismic hazard analysis and discussion of seismic risk. Afghanistan occupies a southward-projecting, relatively stable promontory of the Eurasian tectonic plate (Ambraseys and Bilham, 2003; Wheeler and others, 2005). Active plate boundaries, however, surround Afghanistan on the west, south, and east. To the west, the Arabian plate moves northward relative to Eurasia at about 3 cm/yr. The active plate boundary trends northwestward through the Zagros region of southwestern Iran. Deformation is accommodated throughout the territory of Iran; major structures include several north-south-trending, right-lateral strike-slip fault systems in the east and, farther to the north, a series of east-west-trending reverse- and strike-slip faults. This deformation apparently does not cross the border into relatively stable western Afghanistan. In the east, the Indian plate moves northward relative to Eurasia at a rate of about 4 cm/yr. A broad, transpressional plate-boundary zone extends into eastern Afghanistan, trending southwestward from the Hindu Kush in northeast Afghanistan, through Kabul, and along the Afghanistan-Pakistan border. Deformation here is expressed as a belt of major, north-northeast-trending, left-lateral strike-slip faults and abundant seismicity. The seismicity intensifies farther to the northeast and includes a prominent zone of deep earthquakes associated with northward subduction of the Indian plate beneath Eurasia that extends beneath the Hindu Kush and Pamirs Mountains. Production of the seismic hazard maps is challenging because the geological and seismological data required to produce a seismic hazard model are limited. The data that are available for this project include historical seismicity and poorly constrained slip rates on only a few of the many active faults in the country. Much of the hazard is derived from a new catalog of historical earthquakes: from 1964 to the present, with magnitude equal to or greater than about 4.5, and with depth between 0 and 250 kilometers. We also include four specific faults in the model: the Chaman fault with an assigned slip rate of 10 mm/yr, the Central Badakhshan fault with an assigned slip rate of 12 mm/yr, the Darvaz fault with an assigned slip rate of 7 mm/yr, and the Hari Rud fault with an assigned slip rate of 2 mm/yr. For these faults and for shallow seismicity less than 50 km deep, we incorporate published ground-motion estimates from tectonically active regions of western North America, Europe, and the Middle East. Ground-motion estimates for deeper seismicity are derived from data in subduction environments. We apply estimates derived for tectonic regions where subduction is the main tectonic process for intermediate-depth seismicity between 50- and 250-km depth. Within the framework of these limitations, we have developed a preliminary probabilistic seismic-hazard assessment of Afghanistan, the type of analysis that underpins the seismic components of modern building codes in the United States. The assessment includes maps of estimated peak ground-acceleration (PGA), 0.2-second spectral acceleration (SA), and 1.0-secon

Seismicity map of the state of Georgia

USGS Publications Warehouse

Reagor, B. Glen; Stover, C.W.; Algermissen, S.T.; Long, L.T.

1991-01-01

This map is one of a series of seismicity maps produced by the U.S. Geological Survey that show earthquake data of individual states or groups of states at the scale of 1:1,000,000. This maps shows only those earthquakes with epicenters located within the boundaries of Georgia, even though earthquakes in nearby states or countries may have been felt or may have cause damage in Georgia. The data in table 1 were used to compile the seismicity map; these data are a corrected, expanded, and updated (through 1987) version of the data used by Algermissen (1969) for a study of seismic risk in the United States. The locations and intensities of some earthquakes were revised and intensities were assigned where none had been before. Many earthquakes were added to the original list from new data sources as well as from some old data sources that has not been previously used. The data in table 1 represent best estimates of the location of the epicenter, magnitude, and intensity of each earthquake on the basis of historical and current information. Some of the aftershocks from large earthquakes are listed, but not all, especially for earthquakes that occurred before seismic instruments were universally used. The latitude and longitude coordinates of each epicenter were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped and counted. These locations are represented on the map by a triangle. The number of earthquakes at each location is shown on the map by the Arabic number to the right of the triangle. A Roman numeral to the left of a triangle is the maximum Modified Mercoili intensity (Wood and Neumann, 1931) of all earthquakes at that geographic location, The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. The year shown below each triangle is the latest year for which the maximum intensity was recorded.

Seismicity map of the State of Louisiana

USGS Publications Warehouse

Stover, C.W.; Reagor, B.G.; Algermissen, S.T.

1979-01-01

This map is one of a series of seismicity maps produced by the U. S. Geological Survey that show earthquake data of individual states or groups of states at the scale of 1:1,000,000. This map shows only those earthquakes with epicenters located within the boundaries of Louisiana, even though earthquakes in nearby states or countries may have been felt or may have caused damage in Louisiana.The data in table 1 were used to compile the seismicity map; these data are a corrected, expanded, and updated (through 1983) version of the data used by Algermissen (1969) for a study of seismic risk in the United States. The locations and intensities of some earthquakes were revised and intensities were assigned where none had been before. Many earthquakes were added to the original list from new data sources as well as from some old data sources that had not been previously used. The data in table 1 represent best estimates of the location of the epicenter, magnitude, and intensity of each earthquake on the basis of historical and current information. Some of the aftershocks from large earthquakes are listed, but not all, especially for earthquakes that occurred before seismic instruments were universally used.The latitude and longitude coordinates of each epicenter were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped and counted. These locations are represented on the map by a triangle. The number of earthquakes at each location is shown on the map by the arabic number to the right of the triangle. A Roman numeral to the 1eft of a triangle is the maximum Modified Mercalli intensity (Wood and Neumann, 1931) of all earthquakes at that geographic location. The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. The year shown below each triangle is the latest year for which the maximum intensity was recorded.

Seismicity map of the state of Pennsylvania

USGS Publications Warehouse

Stover, C.W.; Reagor, B.G.; Algermissen, S.T.

1987-01-01

This map is one of a series of seismicity maps produced by the U. S. Geological Survey that show earthquake data of individual states or groups of states at the scale of 1:1,000,000. This map shows only those earthquakes with epicenters located within the boundaries of Pennsylvania, even though earthquakes in nearby states may have been felt or may have caused damage in Pennsylvania.The data in table 1 were used to compile the seismicity map; these data are a corrected, expanded, and updated (through 1983) version of the data used by Algermissen (1969) for a study of seismic risk in the United States. The locations and intensities of some earthquakes were revised and intensities were assigned where none had been before. Many earthquakes were added to the original list from new data sources as well as from some old data sources that had not been previously used. The data in table 1 represent best estimates of the location of the epicenter, magnitude, and intensity of each earthquake on the basis of historical and current information. Some of the aftershocks from large earthquakes are listed, but not all, especially for earthquakes that occurred before seismic instruments were universally used.The latitude and longitude coordinates of each epicenter were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped and counted. These locations are represented on the map by a triangle. The number of earthquakes at each location is shown on the map by the arabic number to the right of the triangle. A Roman numeral to the left of a triangle is the maximum Modified Mercalli intensity (Wood and Neumann, 1931) of a11 earthquakes at that geographic location. The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. The year shown below each triangle is the latest year for which the maximum intensity was recorded.

Anamolous ionospheric TEC variations prior to the Indonesian earthquake (M 7.1) of November 15, 2014

NASA Astrophysics Data System (ADS)

Alcay, Salih

2017-05-01

This paper investigates preearthquake ionospheric variations with the use of TEC of Global Ionospheric Maps (GIMs) and regional maps based on Precise Point Positioning (PPP) during the 7.1-M Indonesian earthquake that occurred on November 15, 2014. TEC maps corresponding to 10 days before to 4 days after the event were examined. In addition, a time series of TEC values according to the PPP maps were also evaluated. In addition to GIMs, it was possible to detect TEC variations with PPP maps. The results showed that ionospheric TEC decreased strikingly 4 days prior to the earthquake. This TEC variation was highly likely related to seismic activity.

Communicating and Evaluating the Causes of Seismicity in Oklahoma Using ArcGIS Online Story Map Web Applications

NASA Astrophysics Data System (ADS)

Justman, D.; Rose, K.; Bauer, J. R.; Miller, R., III; Vasylkivska, V.; Romeo, L.

2016-12-01

ArcGIS Online story maps allows users to communicate complex topics with geospatially enabled stories. This story map web application entitled "Evaluating the Mysteries of Seismicity in Oklahoma" has been employed as part of a broader research effort investigating the relationships between spatiotemporal systems and seismicity to understand the recent increase in seismicity by reviewing literature, exploring, and performing analyses on key datasets. It offers information about the unprecedented increase in seismic events since 2008, earthquake history, the risk to the population, physical mechanisms behind earthquakes, natural and anthropogenic earthquake factors, and individual & cumulative spatial extents of these factors. The cumulative spatial extents for natural, anthropogenic, and all combined earthquake factors were determined using the Cumulative Spatial Impact Layers (CSILs) tool developed at the National Energy Technology Laboratory (NETL). Results show positive correlations between the average number of influences (datasets related to individual factors) and the number of earthquakes for every 100 square mile grid cell in Oklahoma, along with interesting spatial correlations for the individual & cumulative spatial extents of these factors when overlaid with earthquake density and a hotspot analysis for earthquake magnitude from 2010 to 2015.

Spatial Evaluation and Verification of Earthquake Simulators

NASA Astrophysics Data System (ADS)

Wilson, John Max; Yoder, Mark R.; Rundle, John B.; Turcotte, Donald L.; Schultz, Kasey W.

2017-06-01

In this paper, we address the problem of verifying earthquake simulators with observed data. Earthquake simulators are a class of computational simulations which attempt to mirror the topological complexity of fault systems on which earthquakes occur. In addition, the physics of friction and elastic interactions between fault elements are included in these simulations. Simulation parameters are adjusted so that natural earthquake sequences are matched in their scaling properties. Physically based earthquake simulators can generate many thousands of years of simulated seismicity, allowing for a robust capture of the statistical properties of large, damaging earthquakes that have long recurrence time scales. Verification of simulations against current observed earthquake seismicity is necessary, and following past simulator and forecast model verification methods, we approach the challenges in spatial forecast verification to simulators; namely, that simulator outputs are confined to the modeled faults, while observed earthquake epicenters often occur off of known faults. We present two methods for addressing this discrepancy: a simplistic approach whereby observed earthquakes are shifted to the nearest fault element and a smoothing method based on the power laws of the epidemic-type aftershock (ETAS) model, which distributes the seismicity of each simulated earthquake over the entire test region at a decaying rate with epicentral distance. To test these methods, a receiver operating characteristic plot was produced by comparing the rate maps to observed m>6.0 earthquakes in California since 1980. We found that the nearest-neighbor mapping produced poor forecasts, while the ETAS power-law method produced rate maps that agreed reasonably well with observations.

Seismicity and tectonic relationships of the Nemaha Uplift in Oklahoma. Part V. Final report

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

Luza, K.V.; Lawson, J.E. Jr.

1983-02-01

The Nemaha Ridge is composed of a number of crustal blocks typically 3 to 5 miles (5 to 8 km) wide and 5 to 20 miles (8 to 32 km) long. Structure-contour maps prepared of the top of the Viola Formation (Ordovician), the base of the Pennsylvanian, and the top of the Oswego Formation (Middle Pennsylvanian) reveal a complex fault pattern associated with the Nemaha Uplift. This fault pattern is dominated by several discontinuous uplifts, such as the Oklahoma City, Lovell, Garber, and Crescent Uplifts. A detailed study of the Oklahoma City Uplift suggests that a number of the Nemaha-relatedmore » faults were developed in pre-Mississippian time. Many of these faults exhibit both increasing and decreasing displacements from early to late Paleozoic time. However, the displacement for most of the Oklahoma City faults took place between the end of Oswego time and the end of Hunton time. A lineament map was prepared for north-central Oklahoma. A detailed gravity map was prepared for the Kingfisher and Medford maxima. A total-intensity aeromagnetic map for the Enid and Oklahoma City 1/sup 0/ by 2/sup 0/ Quadrangles was prepared. A regional seismograph network was established to supplement existing seismological capability. A local earthquake-location program, named HYPERCUBE, was developed. From 1897 through 1976, Oklahoma has had approximately 128 known earthquakes. After the network became operational in late 1977, 255 additional earthquakes were detected in Oklahoma (through 1981). A study of earthquake distribution and intensity values in Oklahoma led to the development of a seismic-source map for Oklahoma and parts of the adjacent states. Six seismic-source zones were identified. For each zone except one, a magnitude-frequency relationship was determined.« less

Seismic Hazard Assessment of the Sheki-Ismayilli Region, Azerbaijan

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

Ayyubova, Leyla J.

2006-03-23

Seismic hazard assessment is an important factor in disaster management of Azerbaijan Republic. The Shaki-Ismayilli region is one of the earthquake-prone areas in Azerbaijan. According to the seismic zoning map, the region is located in intensity IX zone. Large earthquakes in the region take place along the active faults. The seismic activity of the Shaki-Ismayilli region is studied using macroseismic and instrumental data, which cover the period between 1250 and 2003. Several principal parameters of earthquakes are analyzed: maximal magnitude, energetic class, intensity, depth of earthquake hypocenter, and occurrence. The geological structures prone to large earthquakes are determined, and themore » dependence of magnitude on the fault length is shown. The large earthquakes take place mainly along the active faults. A map of earthquake intensity has been developed for the region, and the potential seismic activity of the Shaki-Ismayilli region has been estimated.« less

Reservoir and Source Rock Identification Based on Geologycal, Geophysics and Petrophysics Analysis Study Case: South Sumatra Basin

NASA Astrophysics Data System (ADS)

Anggit Maulana, Hiska; Haris, Abdul

2018-05-01

Reservoir and source rock Identification has been performed to deliniate the reservoir distribution of Talangakar Formation South Sumatra Basin. This study is based on integrated geophysical, geological and petrophysical data. The aims of study to determine the characteristics of the reservoir and source rock, to differentiate reservoir and source rock in same Talangakar formation, to find out the distribution of net pay reservoir and source rock layers. The method of geophysical included seismic data interpretation using time and depth structures map, post-stack inversion, interval velocity, geological interpretations included the analysis of structures and faults, and petrophysical processing is interpret data log wells that penetrating Talangakar formation containing hydrocarbons (oil and gas). Based on seismic interpretation perform subsurface mapping on Layer A and Layer I to determine the development of structures in the Regional Research. Based on the geological interpretation, trapping in the form of regional research is anticline structure on southwest-northeast trending and bounded by normal faults on the southwest-southeast regional research structure. Based on petrophysical analysis, the main reservoir in the field of research, is a layer 1,375 m of depth and a thickness 2 to 8.3 meters.

Assessing the seismic risk potential of South America

USGS Publications Warehouse

Jaiswal, Kishor; Petersen, Mark D.; Harmsen, Stephen; Smoczyk, Gregory M.

2016-01-01

We present here a simplified approach to quantifying regional seismic risk. The seismic risk for a given region can be inferred in terms of average annual loss (AAL) that represents long-term value of earthquake losses in any one year caused from a long-term seismic hazard. The AAL are commonly measured in the form of earthquake shaking-induced deaths, direct economic impacts or indirect losses caused due to loss of functionality. In the context of South American subcontinent, the analysis makes use of readily available public data on seismicity, population exposure, and the hazard and vulnerability models for the region. The seismic hazard model was derived using available seismic catalogs, fault databases, and the hazard methodologies that are analogous to the U.S. Geological Survey’s national seismic hazard mapping process. The Prompt Assessment of Global Earthquakes for Response (PAGER) system’s direct empirical vulnerability functions in terms of fatality and economic impact were used for performing exposure and risk analyses. The broad findings presented and the risk maps produced herein are preliminary, yet they do offer important insights into the underlying zones of high and low seismic risks in the South American subcontinent. A more detailed analysis of risk may be warranted by engaging local experts, especially in some of the high risk zones identified through the present investigation.

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

Savich, A. I.; Bugaevskii, A. G., E-mail: office@geodyn.ru, E-mail: bugaevskiy@geodyn.ru

Functional dependencies are established for the characteristics of seismic transients recorded at various points of a studied site, which are used to propose a new approach to seismic microzonation (SMZ) that enables the creation of new SMZ maps of strong seismic motion, with due regard for dynamic parameters of recorded transients during weak earthquakes.

Map showing earthquake epicenters (1964-81) in Yellowstone National Park and vicinity, Wyoming, Idaho, and Montana

USGS Publications Warehouse

Pitt, A.M.

1989-01-01

The seismicity displayed on these maps occurred over a 17 year period and was recorded at a variety of seismograph stations, which has resulted in much variation in the reliability and completness of the data set. The earthquake epicenter data are presented on 2 maps. Symbols on map 1 identify events by year of occurrence with the symbol size indicating the magnitude range. Symbols on map 2 indicate the reliability of the earthquake epicenters. Variations in the level of seismicity and strain release with time are shown (Fig. 1), as well as earthquake focal-depth cross sections and representative earthquake focal mechanisms (Fig.2).

Shallow geology, sea-floor texture, and physiographic zones of Vineyard and western Nantucket Sounds, Massachusetts

USGS Publications Warehouse

Baldwin, Wayne E.; Foster, David S.; Pendleton, Elizabeth A.; Barnhardt, Walter A.; Schwab, William C.; Andrews, Brian D.; Ackerman, Seth D.

2016-09-02

Geologic, sediment texture, and physiographic zone maps characterize the sea floor of Vineyard and western Nantucket Sounds, Massachusetts. These maps were derived from interpretations of seismic-reflection profiles, high-resolution bathymetry, acoustic-backscatter intensity, bottom photographs/video, and surficial sediment samples collected within the 494-square-kilometer study area. Interpretations of seismic stratigraphy and mapping of glacial and Holocene marine units provided a foundation on which the surficial maps were created. This mapping is a result of a collaborative effort between the U.S. Geological Survey and the Massachusetts Office of Coastal Zone Management to characterize the surface and subsurface geologic framework offshore of Massachusetts.

Issues in testing the new national seismic hazard model for Italy

NASA Astrophysics Data System (ADS)

Stein, S.; Peresan, A.; Kossobokov, V. G.; Brooks, E. M.; Spencer, B. D.

2016-12-01

It is important to bear in mind that we know little about how earthquake hazard maps actually describe the shaking that will actually occur in the future, and have no agreed way of assessing how well a map performed in the past, and, thus, whether one map performs better than another. Moreover, we should not forget that different maps can be useful for different end users, who may have different cost-and-benefit strategies. Thus, regardless of the specific tests we chose to use, the adopted testing approach should have several key features: We should assess map performance using all the available instrumental, paleo seismology, and historical intensity data. Instrumental data alone span a period much too short to capture the largest earthquakes - and thus strongest shaking - expected from most faults. We should investigate what causes systematic misfit, if any, between the longest record we have - historical intensity data available for the Italian territory from 217 B.C. to 2002 A.D. - and a given hazard map. We should compare how seismic hazard maps developed over time. How do the most recent maps for Italy compare to earlier ones? It is important to understand local divergences that show how the models are developing to the most recent one. The temporal succession of maps is important: we have to learn from previous errors. We should use the many different tests that have been proposed. All are worth trying, because different metrics of performance show different aspects of how a hazard map performs and can be used. We should compare other maps to the ones we are testing. Maps can be made using a wide variety of assumptions, which will lead to different predicted shaking. It is possible that maps derived by other approaches may perform better. Although Italian current codes are based on probabilistic maps, it is important from both a scientific and societal perspective to look at all options including deterministic scenario based ones. Comparing what works better, according to different performance measures, will give valuable insight into key map parameters and assumptions. We may well find that different maps perform better in different applications.

Evaluation of the Seismic Hazard in Venezuela with a revised seismic catalog that seeks for harmonization along the country borders

NASA Astrophysics Data System (ADS)

Rendon, H.; Alvarado, L.; Paolini, M.; Olbrich, F.; González, J.; Ascanio, W.

2013-05-01

Probabilistic Seismic Hazard Assessment is a complex endeavor that relies on the quality of the information that comes from different sources: the seismic catalog, active faults parameters, strain rates, etc. Having this in mind, during the last several months, the FUNVISIS seismic hazard group has been working on a review and update of the local data base that form the basis for a reliable PSHA calculation. In particular, the seismic catalog, which provides the necessary information that allows the evaluation of the critical b-value, which controls how seismic occurrence distributes with magnitude, has received particular attention. The seismic catalog is the result of the effort of several generations of researchers along the years; therefore, the catalog necessarily suffers from the lack of consistency, homogeneity and completeness for all ranges of magnitude over any seismic study area. Merging the FUNVISIS instrumental catalog with the ones obtained from international agencies, we present the work that we have been doing to produce a consistent seismic catalog that covers Venezuela entirely, with seismic events starting from 1910 until 2012, and report the magnitude of completeness for the different periods. Also, we present preliminary results on the Seismic Hazard evaluation that takes into account such instrumental catalog, the historical catalog, updated known fault geometries and its correspondent parameters, and the new seismic sources that have been defined accordingly. Within the spirit of the Global Earthquake Model (GEM), all these efforts look for possible bridges with neighboring countries to establish consistent hazard maps across the borders.

Comment on "How can seismic hazard around the New Madrid seismic zone be similar to that in California?" by Arthur Frankel

USGS Publications Warehouse

Wang, Z.; Shi, B.; Kiefer, J.D.

2005-01-01

PSHA is the method used most to assess seismic hazards for input into various aspects of public and financial policy. For example, PSHA was used by the U.S. Geological Survey to develop the National Seismic Hazard Maps (Frankel et al., 1996, 2002). These maps are the basis for many national, state, and local seismic safety regulations and design standards, such as the NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures, the International Building Code, and the International Residential Code. Adoption and implementation of these regulations and design standards would have significant impacts on many communities in the New Madrid area, including Memphis, Tennessee and Paducah, Kentucky. Although "mitigating risks to society from earthquakes involves economic and policy issues" (Stein, 2004), seismic hazard assessment is the basis. Seismologists should provide the best information on seismic hazards and communicate them to users and policy makers. There is a lack of effort in communicating the uncertainties in seismic hazard assessment in the central U.S., however. Use of 10%, 5%, and 2% PE in 50 years causes confusion in communicating seismic hazard assessment. It would be easy to discuss and understand the design ground motions if the true meaning of the ground motion derived from PSHA were presented, i.e., the ground motion with the estimated uncertainty or the associated confidence level.

Investigation of sea-level changes and shelf break prograding sequences during the Late Quaternary offshore of Kusadasi (West Anatolia) and surroundings by high resolution seismic methods

NASA Astrophysics Data System (ADS)

Gurcay, Savas; Cifci, Gunay; Dondurur, Derman; Okay, Seda; Atgin, Orhan; Ozel, Ozkan; Mert Kucuk, Hilmi

2016-04-01

High Resolution multi-channel seismic reflection and Chirp data were collected by K. Piri Reis, research vessel of Dokuz Eylül University, in the central Aegean coast of the West Anatolia by research cruises carried out in 2005 and 2008, respectively. Submarine stratigraphic and structural features of Sıǧacık Gulf, Kuşadası Gulf and surroundings were investigated under this survey. The data were processed and interpreted in SeisLab, D.E.U. Marine Sciences and Technology seismic laboratory. Thirteen distinct unconformities can be traced below the study area that separate thirteen progradational stacked paleo-delta sequences (Lob1-Lob13) on seismic profiles following and cutting each other. As a result of comparison with the oxygen isotopic stages (δ18), these deltas (Lob1-L13) were interpreted that they have been deposited during the sea-level lowstands within Pleistocene glacial stages. In the study area the basement surface which observed as the lowest unconformity surface of the seismic sections was called 'Acoustic Basement'. This basement which traced approximately all of the seismic sections has generally quite wavy surface and underlain the upper seismic units. It was observed that these seismic units which terminated their formation in Pleistocene (Lob1-Lob13) and Holocene period were cut and uplifted by acoustic basement, like an intrusion. These type deformations were interpreted as a result of magmatic intrusion into these upper seismic units occurred in Late Pleistocene and Holocene period. Tectonic and structural interpretation was carried out to constitute the submarine active tectonic map of the study area by correlated active faults identified on seismic sections. Submarine active tectonic map and, basement topography and sediment thickness map were correlated together to present the relationship between tectonic deformation and stratigraphy.

Interseismic Coupling, Co- and Post-seismic Slip: a Stochastic View on the Northern Chilean Subduction Zone

NASA Astrophysics Data System (ADS)

Jolivet, R.; Duputel, Z.; Simons, M.; Jiang, J.; Riel, B. V.; Moore, A. W.; Owen, S. E.

2017-12-01

Mapping subsurface fault slip during the different phases of the seismic cycle provides a probe of the mechanical properties and the state of stress along these faults. We focus on the northern Chile megathrust where first order estimates of interseismic fault locking suggests little to no overlap between regions slipping seismically versus those that are dominantly aseismic. However, published distributions of slip, be they during seismic or aseismic phases, rely on unphysical regularization of the inverse problem, thereby cluttering attempts to quantify the degree of overlap between seismic and aseismic slip. Considering all the implications of aseismic slip on our understanding of the nucleation, propagation and arrest of seismic ruptures, it is of utmost importance to quantify our confidence in the current description of fault coupling. Here, we take advantage of 20 years of InSAR observations and more than a decade of GPS measurements to derive probabilistic maps of inter-seismic coupling, as well as co-seismic and post-seismic slip along the northern Chile subduction megathrust. A wide InSAR velocity map is derived using a novel multi-pixel time series analysis method accounting for orbital errors, atmospheric noise and ground deformation. We use AlTar, a massively parallel Monte Carlo Markov Chain algorithm exploiting the acceleration capabilities of Graphic Processing Units, to derive the probability density functions (PDF) of slip. In northern Chile, we find high probabilities for a complete release of the elastic strain accumulated since the 1877 earthquake by the 2014, Iquique earthquake and for the presence of a large, independent, locked asperity left untapped by recent events, north of the Mejillones peninsula. We evaluate the probability of overlap between the co-, inter- and post-seismic slip and consider the potential occurrence of slow, aseismic slip events along this portion of the subduction zone.

Drone based structural mapping at Holuhraun indicates fault reactivation and complexity

NASA Astrophysics Data System (ADS)

Mueller, Daniel; Walter, Thomas R.; Steinke, Bastian; Witt, Tanja; Schoepa, Anne; Duerig, Tobi; Gudmundsson, Magnus T.

2016-04-01

Accompanied by an intense seismic swarm in August 2014, a dike laterally formed, starting under Icelands Vatnajökull glacier, propagating over a distance of more than 45 km within only two weeks, leading to the largest eruption by volume since the 1783-84 Laki eruption. Along its propagation path, the dike caused intense surface displacements up to meters. Based on seismicity, GPS and InSAR, the propagation has already been analysed and described as segmented lateral dike growth. We now focus on few smaller regions of the dike. We consider the Terrasar-X tandem digital elevation map and aerial photos and find localized zones where structural fissures formed and curved. At these localized, regions we performed a field campaign in summer 2015, applying the close range remote sensing techniques Structure from Motion (SfM) and Terrestrial Laser Scanning (TLS). Over 4 TLS scan were collected, along with over 5,000 aerial images. Point clouds from SfM and TLS are merged and compared, and local structural lineaments analysed. As a result, we obtained an unprecedentedly high-resolution digital elevation map. With this map, we analyse the structural expression of the fissure eruption at the surface and improve understanding on the conditions that influenced the magma propagation path. We elaborate scenarios that lead to complexities of the surface structures and the link to the underlying dike intrusion.

Seismically induced landslides: current research by the US Geological Survey.

USGS Publications Warehouse

Harp, E.L.; Wilson, R.C.; Keefer, D.K.; Wieczorek, G.F.

1986-01-01

We have produced a regional seismic slope-stability map and a probabilistic prediction of landslide distribution from a postulated earthquake. For liquefaction-induced landslides, in situ measurements of seismically induced pore-water pressures have been used to establish an elastic model of pore pressure generation. -from Authors

Understanding earthquake hazards in urban areas - Evansville Area Earthquake Hazards Mapping Project

USGS Publications Warehouse

Boyd, Oliver S.

2012-01-01

The region surrounding Evansville, Indiana, has experienced minor damage from earthquakes several times in the past 200 years. Because of this history and the proximity of Evansville to the Wabash Valley and New Madrid seismic zones, there is concern among nearby communities about hazards from earthquakes. Earthquakes currently cannot be predicted, but scientists can estimate how strongly the ground is likely to shake as a result of an earthquake and are able to design structures to withstand this estimated ground shaking. Earthquake-hazard maps provide one way of conveying such information and can help the region of Evansville prepare for future earthquakes and reduce earthquake-caused loss of life and financial and structural loss. The Evansville Area Earthquake Hazards Mapping Project (EAEHMP) has produced three types of hazard maps for the Evansville area: (1) probabilistic seismic-hazard maps show the ground motion that is expected to be exceeded with a given probability within a given period of time; (2) scenario ground-shaking maps show the expected shaking from two specific scenario earthquakes; (3) liquefaction-potential maps show how likely the strong ground shaking from the scenario earthquakes is to produce liquefaction. These maps complement the U.S. Geological Survey's National Seismic Hazard Maps but are more detailed regionally and take into account surficial geology, soil thickness, and soil stiffness; these elements greatly affect ground shaking.

Aerospace technology can be applied to exploration 'back on earth'. [offshore petroleum resources

NASA Technical Reports Server (NTRS)

Jaffe, L. D.

1977-01-01

Applications of aerospace technology to petroleum exploration are described. Attention is given to seismic reflection techniques, sea-floor mapping, remote geochemical sensing, improved drilling methods and down-hole acoustic concepts, such as down-hole seismic tomography. The seismic reflection techniques include monitoring of swept-frequency explosive or solid-propellant seismic sources, as well as aerial seismic surveys. Telemetry and processing of seismic data may also be performed through use of aerospace technology. Sea-floor sonor imaging and a computer-aided system of geologic analogies for petroleum exploration are also considered.

Spatio-temporal earthquake risk assessment for the Lisbon Metropolitan Area - A contribution to improving standard methods of population exposure and vulnerability analysis

NASA Astrophysics Data System (ADS)

Freire, Sérgio; Aubrecht, Christoph

2010-05-01

The recent 7.0 M earthquake that caused severe damage and destruction in parts of Haiti struck close to 5 PM (local time), at a moment when many people were not in their residences, instead being in their workplaces, schools, or churches. Community vulnerability assessment to seismic hazard relying solely on the location and density of resident-based census population, as is commonly the case, would grossly misrepresent the real situation. In particular in the context of global (climate) change, risk analysis is a research field increasingly gaining in importance whereas risk is usually defined as a function of hazard probability and vulnerability. Assessment and mapping of human vulnerability has however generally been lagging behind hazard analysis efforts. Central to the concept of vulnerability is the issue of human exposure. Analysis of exposure is often spatially tied to administrative units or reference objects such as buildings, spanning scales from the regional level to local studies for small areas. Due to human activities and mobility, the spatial distribution of population is time-dependent, especially in metropolitan areas. Accurately estimating population exposure is a key component of catastrophe loss modeling, one element of effective risk analysis and emergency management. Therefore, accounting for the spatio-temporal dynamics of human vulnerability correlates with recent recommendations to improve vulnerability analyses. Earthquakes are the prototype for a major disaster, being low-probability, rapid-onset, high-consequence events. Lisbon, Portugal, is subject to a high risk of earthquake, which can strike at any day and time, as confirmed by modern history (e.g. December 2009). The recently-approved Special Emergency and Civil Protection Plan (PEERS) is based on a Seismic Intensity map, and only contemplates resident population from the census as proxy for human exposure. In the present work we map and analyze the spatio-temporal distribution of population in the daily cycle to re-assess exposure to earthquake hazard in the Lisbon Metropolitan Area, home to almost three million people. New high-resolution (50 m grids) daytime and nighttime population distribution maps are developed using dasymetric mapping. The modeling approach uses areal interpolation to combine best-available census data and statistics with land use and land cover data. Mobility statistics are considered for mapping daytime distribution, and empirical parameters used for interpolation are obtained from a previous effort in high resolution population mapping of part of the study area. Finally, the population distribution maps are combined with the Seismic Hazard Intensity map to: (1) quantify and compare human exposure to seismic intensity levels in the daytime and nighttime periods, and (2) derive nighttime and daytime overall Earthquake Risk maps. This novel approach yields previously unavailable spatio-temporal population distribution information for the study area, enabling refined and more accurate earthquake risk mapping and assessment. Additionally, such population exposure datasets can be combined with different hazard maps to improve spatio-temporal assessment and risk mapping for any type of hazard, natural or man-made. We believe this improved characterization of vulnerability and risk can benefit all phases of the disaster management process where human exposure has to be considered, namely in emergency planning, risk mitigation, preparedness, and response to an event.

New "Risk-Targeted" Seismic Maps Introduced into Building Codes

USGS Publications Warehouse

Luco, Nicholas; Garrett, B.; Hayes, J.

2012-01-01

Throughout most municipalities of the United States, structural engineers design new buildings using the U.S.-focused International Building Code (IBC). Updated editions of the IBC are published every 3 years. The latest edition (2012) contains new "risk-targeted maximum considered earthquake" (MCER) ground motion maps, which are enabling engineers to incorporate a more consistent and better defined level of seismic safety into their building designs.

When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy - Part 1: Model components for sources parameterization

NASA Astrophysics Data System (ADS)

Azzaro, Raffaele; Barberi, Graziella; D'Amico, Salvatore; Pace, Bruno; Peruzza, Laura; Tuvè, Tiziana

2017-11-01

The volcanic region of Mt. Etna (Sicily, Italy) represents a perfect lab for testing innovative approaches to seismic hazard assessment. This is largely due to the long record of historical and recent observations of seismic and tectonic phenomena, the high quality of various geophysical monitoring and particularly the rapid geodynamics clearly demonstrate some seismotectonic processes. We present here the model components and the procedures adopted for defining seismic sources to be used in a new generation of probabilistic seismic hazard assessment (PSHA), the first results and maps of which are presented in a companion paper, Peruzza et al. (2017). The sources include, with increasing complexity, seismic zones, individual faults and gridded point sources that are obtained by integrating geological field data with long and short earthquake datasets (the historical macroseismic catalogue, which covers about 3 centuries, and a high-quality instrumental location database for the last decades). The analysis of the frequency-magnitude distribution identifies two main fault systems within the volcanic complex featuring different seismic rates that are controlled essentially by volcano-tectonic processes. We discuss the variability of the mean occurrence times of major earthquakes along the main Etnean faults by using an historical approach and a purely geologic method. We derive a magnitude-size scaling relationship specifically for this volcanic area, which has been implemented into a recently developed software tool - FiSH (Pace et al., 2016) - that we use to calculate the characteristic magnitudes and the related mean recurrence times expected for each fault. Results suggest that for the Mt. Etna area, the traditional assumptions of uniform and Poissonian seismicity can be relaxed; a time-dependent fault-based modeling, joined with a 3-D imaging of volcano-tectonic sources depicted by the recent instrumental seismicity, can therefore be implemented in PSHA maps. They can be relevant for the retrofitting of the existing building stock and for driving risk reduction interventions. These analyses do not account for regional M > 6 seismogenic sources which dominate the hazard over long return times (≥ 500 years).

Breakup magmatism on the Vøring Margin, mid-Norway: New insight from interpretation of high-quality 2D and 3D seismic reflection data

NASA Astrophysics Data System (ADS)

Abdelmalak, M. M.; Planke, S.; Millett, J.; Jerram, D. A.; Maharjan, D.; Zastrozhnov, D.; Schmid, D. W.; Faleide, J. I.; Svensen, H.; Myklebust, R.

2017-12-01

The Vøring Margin offshore mid-Norway is a classic volcanic rifted margin, characterized by voluminous Paleogene igneous rocks present on both sides of the continent-ocean boundary. The margin displays (1) thickened transitional crust with a well-defined lower crustal high-velocity body and prominent deep crustal reflections, the so-called T-Reflection, (2) seaward dipping reflector (SDR) wedges and a prominent northeast-trending escarpment on the Vøring Marginal High, and (3) extensive sill complexes in the adjacent Cretaceous Vøring Basin. During the last decade, new 2D and 3D industry seismic data along with improved processing techniques, such as broadband processing and noise reduction processing sequences, have made it possible to image and map the breakup igneous complex in much greater detail than previously possible. Our interpretation includes a combination of (1) seismic horizon picking, (2) integrated seismic-gravity-magnetic (SGM) interpretation, (3) seismic volcanostratigraphy, and (4) igneous seismic geomorphology. The results are integrated with published wide-angle seismic data, re-analyzed borehole data including new geochronology, and new geodynamic modeling of the effects of magmatism on the thermal history and subsidence of the margin. The extensive sill complexes and associated hydrothermal vent complexes in the Vøring Basin have a Paleocene-Eocene boundary age based on high-precision U/Pb dating combined with seismic mapping constraints. On the marginal high, our results show a highly variable crustal structure, with a pre-breakup configuration consisting of large-scale structural highs and sedimentary basins. These structures were in-filled and covered by basalt flows and volcanogenic sediments during the early stages of continental breakup in the earliest Eocene. Subsequently, rift basins developed along the continent-ocean boundary and where infilled by up to ca. 6 km thick basalt sequences, currently imaged as SDRs fed by a dike swarm imaged on seismic data. The addition of magma within the crust had a prominent effect on the thermal history and hydrocarbon maturation of the sedimentary basin, causing uplift, delayed subsidence, and possibly contributing to the triggering of global warming during the Paleocene-Eocene Thermal Maximum (PETM).

Logistic Regression for Seismically Induced Landslide Predictions: Using Uniform Hazard and Geophysical Layers as Predictor Variables

NASA Astrophysics Data System (ADS)

Nowicki, M. A.; Hearne, M.; Thompson, E.; Wald, D. J.

2012-12-01

Seismically induced landslides present a costly and often fatal threats in many mountainous regions. Substantial effort has been invested to understand where seismically induced landslides may occur in the future. Both slope-stability methods and, more recently, statistical approaches to the problem are described throughout the literature. Though some regional efforts have succeeded, no uniformly agreed-upon method is available for predicting the likelihood and spatial extent of seismically induced landslides. For use in the U. S. Geological Survey (USGS) Prompt Assessment of Global Earthquakes for Response (PAGER) system, we would like to routinely make such estimates, in near-real time, around the globe. Here we use the recently produced USGS ShakeMap Atlas of historic earthquakes to develop an empirical landslide probability model. We focus on recent events, yet include any digitally-mapped landslide inventories for which well-constrained ShakeMaps are also available. We combine these uniform estimates of the input shaking (e.g., peak acceleration and velocity) with broadly available susceptibility proxies, such as topographic slope and surface geology. The resulting database is used to build a predictive model of the probability of landslide occurrence with logistic regression. The landslide database includes observations from the Northridge, California (1994); Wenchuan, China (2008); ChiChi, Taiwan (1999); and Chuetsu, Japan (2004) earthquakes; we also provide ShakeMaps for moderate-sized events without landslide for proper model testing and training. The performance of the regression model is assessed with both statistical goodness-of-fit metrics and a qualitative review of whether or not the model is able to capture the spatial extent of landslides for each event. Part of our goal is to determine which variables can be employed based on globally-available data or proxies, and whether or not modeling results from one region are transferrable to geomorphologically-similar regions that lack proper calibration events. Combined with near-real time ShakeMaps, we anticipate using our model to make generalized predictions of whether or not (and if so, where) landslides are likely to occur for earthquakes around the globe; we also intend to incorporate this functionality into the USGS PAGER system.

Preliminary Seismic Probabilistic Tsunami Hazard Map for Italy

NASA Astrophysics Data System (ADS)

Lorito, Stefano; Selva, Jacopo; Basili, Roberto; Grezio, Anita; Molinari, Irene; Piatanesi, Alessio; Romano, Fabrizio; Tiberti, Mara Monica; Tonini, Roberto; Bonini, Lorenzo; Michelini, Alberto; Macias, Jorge; Castro, Manuel J.; González-Vida, José Manuel; de la Asunción, Marc

2015-04-01

We present a preliminary release of the first seismic probabilistic tsunami hazard map for Italy. The map aims to become an important tool for the Italian Department of Civil Protection (DPC), as well as a support tool for the NEAMTWS Tsunami Service Provider, the Centro Allerta Tsunami (CAT) at INGV, Rome. The map shows the offshore maximum tsunami elevation expected for several average return periods. Both crustal and subduction earthquakes are considered. The probability for each scenario (location, depth, mechanism, source size, magnitude and temporal rate) is defined on a uniform grid covering the entire Mediterranean for crustal earthquakes and on the plate interface for subduction earthquakes. Activity rates are assigned from seismic catalogues and basing on a tectonic regionalization of the Mediterranean area. The methodology explores the associated aleatory uncertainty through the innovative application of an Event Tree. Main sources of epistemic uncertainty are also addressed although in preliminary way. The whole procedure relies on a database of pre-calculated Gaussian-shaped Green's functions for the sea level elevation, to be used also as a real time hazard assessment tool by CAT. Tsunami simulations are performed using the non-linear shallow water multi-GPU code HySEA, over a 30 arcsec bathymetry (from the SRTM30+ dataset) and the maximum elevations are stored at the 50-meter isobath and then extrapolated through the Green's law at 1 meter depth. This work is partially funded by project ASTARTE - Assessment, Strategy And Risk Reduction for Tsunamis in Europe - FP7-ENV2013 6.4-3, Grant 603839, and by the Italian flagship project RITMARE.

Risk-targeted versus current seismic design maps for the conterminous United States

USGS Publications Warehouse

Luco, Nicolas; Ellingwood, Bruce R.; Hamburger, Ronald O.; Hooper, John D.; Kimball, Jeffrey K.; Kircher, Charles A.

2007-01-01

The probabilistic portions of the seismic design maps in the NEHRP Provisions (FEMA, 2003/2000/1997), and in the International Building Code (ICC, 2006/2003/2000) and ASCE Standard 7-05 (ASCE, 2005a), provide ground motion values from the USGS that have a 2% probability of being exceeded in 50 years. Under the assumption that the capacity against collapse of structures designed for these "uniformhazard" ground motions is equal to, without uncertainty, the corresponding mapped value at the location of the structure, the probability of its collapse in 50 years is also uniform. This is not the case however, when it is recognized that there is, in fact, uncertainty in the structural capacity. In that case, siteto-site variability in the shape of ground motion hazard curves results in a lack of uniformity. This paper explains the basis for proposed adjustments to the uniform-hazard portions of the seismic design maps currently in the NEHRP Provisions that result in uniform estimated collapse probability. For seismic design of nuclear facilities, analogous but specialized adjustments have recently been defined in ASCE Standard 43-05 (ASCE, 2005b). In support of the 2009 update of the NEHRP Provisions currently being conducted by the Building Seismic Safety Council (BSSC), herein we provide examples of the adjusted ground motions for a selected target collapse probability (or target risk). Relative to the probabilistic MCE ground motions currently in the NEHRP Provisions, the risk-targeted ground motions for design are smaller (by as much as about 30%) in the New Madrid Seismic Zone, near Charleston, South Carolina, and in the coastal region of Oregon, with relatively little (<15%) change almost everywhere else in the conterminous U.S.

Did you feel it? Community-made earthquake shaking maps

USGS Publications Warehouse

Wald, D.J.; Wald, L.A.; Dewey, J.W.; Quitoriano, Vince; Adams, Elisabeth

2001-01-01

Since the early 1990's, the magnitude and location of an earthquake have been available within minutes on the Internet. Now, as a result of work by the U.S. Geological Survey (USGS) and with the cooperation of various regional seismic networks, people who experience an earthquake can go online and share information about its effects to help create a map of shaking intensities and damage. Such 'Community Internet Intensity Maps' (CIIM's) contribute greatly in quickly assessing the scope of an earthquake emergency, even in areas lacking seismic instruments.

Visualising uncertainty: interpreting quantified geoscientific inversion outputs for a diverse user community.

NASA Astrophysics Data System (ADS)

Reading, A. M.; Morse, P. E.; Staal, T.

2017-12-01

Geoscientific inversion outputs, such as seismic tomography contour images, are finding increasing use amongst scientific user communities that have limited knowledge of the impact of output parameter uncertainty on subsequent interpretations made from such images. We make use of a newly written computer application which enables seismic tomography images to be displayed in a performant 3D graphics environment. This facilitates the mapping of colour scales to the human visual sensorium for the interactive interpretation of contoured inversion results incorporating parameter uncertainty. Two case examples of seismic tomography inversions or contoured compilations are compared from the southern hemisphere continents of Australia and Antarctica. The Australian example is based on the AuSREM contoured seismic wavespeed model while the Antarctic example is a valuable but less well constrained result. Through adjusting the multiple colour gradients, layer separations, opacity, illumination, shadowing and background effects, we can optimise the insights obtained from the 3D structure in the inversion compilation or result. Importantly, we can also limit the display to show information in a way that is mapped to the uncertainty in the 3D result. Through this practical application, we demonstrate that the uncertainty in the result can be handled through a well-posed mapping of the parameter values to displayed colours in the knowledge of what is perceived visually by a typical human. We found that this approach maximises the chance of a useful tectonic interpretation by a diverse scientific user community. In general, we develop the idea that quantified inversion uncertainty can be used to tailor the way that the output is presented to the analyst for scientific interpretation.

Mapping nuclear craters on Enewetak Atoll, Marshall Islands

USGS Publications Warehouse

Hampson, John C., Jr.

1986-01-01

In 1984, the U.S. Geological Survey conducted a detailed geologic analysis of two nuclear test craters at Enewetak Atoll, Marshall Islands, on behalf of the Defense Nuclear Agency. A multidisciplinary task force mapped the morphology, surface character, and subsurface structure of two craters, OAK and KOA. The field mapping techniques include echo sounding, sidescan sonar imaging, single-channel and multichannel seismic reflection profiling, a seismic refraction survey, and scuba and submersible operations. All operations had to be navigated precisely and correlatable with subsequent drilling and sampling operations. Mapping with a high degree of precision at scales as large as 1:1500 required corrections that often are not considered in marine mapping. Corrections were applied to the bathymetric data for location of the echo- sounding transducer relative to the navigation transponder on the ship and for transducer depth, speed of sound, and tidal variations. Sidescan sonar, single-channel seismic reflection, and scuba and submersible data were correlated in depth and map position with the bathymetric data to provide a precise, internally consistent data set. The multichannel and refraction surveys were conducted independently but compared well with bathymetry. Examples drawn from processing the bathymetric, sidescan sonar, and single- channel reflection data help illustrate problems and procedures in precision mapping.

Mineral texture based seismic properties of meta-sedimentary and meta-igneous rocks in the orogenic wedge of the Central Scandinavian Caledonides

NASA Astrophysics Data System (ADS)

Almqvist, B. S. G.; Czaplinska, D.; Piazolo, S.

2015-12-01

Progress in seismic methods offers the possibility to visualize in ever greater detail the structure and composition of middle to lower continental crust. Ideally, the seismic parameters, including compressional (Vp) and shear (Vs) wave velocities, anisotropy and Vp/Vs-ratio, allow the inference of detailed and quantitative information on the deformation conditions, chemical composition, temperature and the amount and geometry of fluids and melts in the crust. However, such inferences regarding the crust should be calibrated with known mineral and rock physical properties. Seismic properties calculated from the crystallographic preferred orientation (CPO) and laboratory measurements on representative core material allow us to quantify the interpretations from seismic data. The challenge of such calibrations lies in the non-unique interpretation of seismic data. A large catalogue of physical rock properties is therefore useful, with as many constraining geophysical parameters as possible (including anisotropy and Vp/Vs ratio). We present new CPO data and modelled seismic properties for amphibolite and greenschist grade rocks representing the orogenic wedge in the Central Scandinavian Caledonides. Samples were collected from outcrops in the field and from a 2.5 km long drill core, which penetrated an amphibolite-grade allochthonous unit composed of meta-sedimentary and meta-igneous rocks, as well as mica and chlorite-rich mylonites. The textural data was acquired using large area electron backscatter diffraction (EBSD) maps, and the chemical composition of minerals obtained by energy dispersive x-ray (EDS). Based on the texture data, we compare and evaluate some of the existing methods to calculate texture-based seismic properties of rocks. The suite of samples consists of weakly anisotropic rocks such as felsic gneiss and calc-silicates, and more anisotropic amphibolite, metagabbro, mica-schist. The newly acquired dataset provides a range of seismic properties that improves compositional and structural characterization of deformed middle and lower crust.

California State Waters Map Series-Offshore of Point Reyes, California

USGS Publications Warehouse

Watt, Janet T.; Dartnell, Peter; Golden, Nadine E.; Greene, H. Gary; Erdey, Mercedes D.; Cochrane, Guy R.; Johnson, Samuel Y.; Hartwell, Stephen R.; Kvitek, Rikk G.; Manson, Michael W.; Endris, Charles A.; Dieter, Bryan E.; Sliter, Ray W.; Krigsman, Lisa M.; Lowe, Erik; Chinn, John L.; Watt, Janet T.; Cochran, Susan A.

2015-01-01

This publication about the Offshore of Point Reyes map area includes ten map sheets that contain explanatory text, in addition to this descriptive pamphlet and a data catalog of geographic information system (GIS) files. Sheets 1, 2, and 3 combine data from four different sonar surveys to generate comprehensive high-resolution bathymetry and acoustic-backscatter coverage of the map area. These data reveal a range of physiographic features (highlighted in the perspective views on sheet 4) such as the flat, sediment-covered seafloor in Drakes Bay, as well as abundant “scour depressions” on the Bodega Head–Tomales Point shelf (see sheet 9) and local, tectonically controlled bedrock uplifts. To validate geological and biological interpretations of the sonar data shown in sheets 1, 2, and 3, the U.S. Geological Survey towed a camera sled over specific offshore locations, collecting both video and photographic imagery; these “ground-truth” surveying data are summarized on sheet 6. Sheet 5 is a “seafloor character” map, which classifies the seafloor on the basis of depth, slope, rugosity (ruggedness), and backscatter intensity and which is further informed by the ground-truth-survey imagery. Sheet 7 is a map of “potential habitats,” which are delineated on the basis of substrate type, geomorphology, seafloor process, or other attributes that may provide a habitat for a specific species or assemblage of organisms. Sheet 8 compiles representative seismic-reflection profiles from the map area, providing information on the subsurface stratigraphy and structure of the map area. Sheet 9 shows the distribution and thickness of young sediment (deposited over the last about 21,000 years, during the most recent sea-level rise) in both the map area and the larger Salt Point to Drakes Bay region, interpreted on the basis of the seismic-reflection data, and it identifies the Offshore of Point Reyes map area as lying within the Bodega Head–Tomales Point shelf, Point Reyes bar, and Bolinas shelf domains. Sheet 10 is a geologic map that merges onshore geologic mapping (compiled from existing maps by the California Geological Survey) and new offshore geologic mapping that is based on integration of high-resolution bathymetry and backscatter imagery (sheets 1, 2, 3), seafloor-sediment and rock samples (Reid and others, 2006), digital camera and video imagery (sheet 6), and high-resolution seismic-reflection profiles (sheet 8), as well as aerial-photographic interpretation of nearshore areas. The information provided by the map sheets, pamphlet, and data catalog have a broad range of applications. High-resolution bathymetry, acoustic backscatter, ground-truth-surveying imagery, and habitat mapping all contribute to habitat characterization and ecosystem-based management by providing essential data for delineation of marine protected areas and ecosystem restoration. Many of the maps provide high-resolution baselines that will be critical for monitoring environmental change associated with climate change, coastal development, or other forcings. High-resolution bathymetry is a critical component for modeling coastal flooding caused by storms and tsunamis, as well as inundation associated with longer term sea-level rise. Seismic-reflection and bathymetric data help characterize earthquake and tsunami sources, critical for natural-hazard assessments of coastal zones. Information on sediment distribution and thickness is essential to the understanding of local and regional sediment transport, as well as the development of regional sediment-management plans. In addition, siting of any new offshore infrastructure (for example, pipelines, cables, or renewable-energy facilities) will depend on high-resolution mapping. Finally, this mapping will both stimulate and enable new scientific research and also raise public awareness of, and education about, coastal environments and issues.

Mapping NEHRP VS30 site classes

USGS Publications Warehouse

Holzer, T.L.; Padovani, A.C.; Bennett, M.J.; Noce, T.E.; Tinsley, J. C.

2005-01-01

Site-amplification potential in a 140-km2 area on the eastern shore of San Francisco Bay, California, was mapped with data from 210 seismic cone penetration test (SCPT) soundings. NEHRP VS30 values were computed on a 50-m grid by both taking into account the thickness and using mean values of locally measured shear-wave velocities of shallow geologic units. The resulting map of NEHRP VS30 site classes differs from other published maps that (1) do not include unit thickness and (2) are based on regional compilations of velocity. Although much of the area in the new map is now classified as NEHRP Site Class D, the velocities of the geologic deposits within this area are either near the upper or lower VS30 boundary of Class D. If maps of NEHRP site classes are to be based on geologic maps, velocity distributions of geologic units may need to be considered in the definition of VS30 boundaries of NEHRP site classes. ?? 2005, Earthquake Engineering Research Institute.

Unsupervised seismic facies analysis with spatial constraints using regularized fuzzy c-means

NASA Astrophysics Data System (ADS)

Song, Chengyun; Liu, Zhining; Cai, Hanpeng; Wang, Yaojun; Li, Xingming; Hu, Guangmin

2017-12-01

Seismic facies analysis techniques combine classification algorithms and seismic attributes to generate a map that describes main reservoir heterogeneities. However, most of the current classification algorithms only view the seismic attributes as isolated data regardless of their spatial locations, and the resulting map is generally sensitive to noise. In this paper, a regularized fuzzy c-means (RegFCM) algorithm is used for unsupervised seismic facies analysis. Due to the regularized term of the RegFCM algorithm, the data whose adjacent locations belong to same classification will play a more important role in the iterative process than other data. Therefore, this method can reduce the effect of seismic data noise presented in discontinuous regions. The synthetic data with different signal/noise values are used to demonstrate the noise tolerance ability of the RegFCM algorithm. Meanwhile, the fuzzy factor, the neighbour window size and the regularized weight are tested using various values, to provide a reference of how to set these parameters. The new approach is also applied to a real seismic data set from the F3 block of the Netherlands. The results show improved spatial continuity, with clear facies boundaries and channel morphology, which reveals that the method is an effective seismic facies analysis tool.

4D seismic monitoring of the miscible CO2 flood of Hall-Gurney Field, Kansas, U.S

USGS Publications Warehouse

Raef, A.E.; Miller, R.D.; Byrnes, A.P.; Harrison, W.E.

2004-01-01

A cost-effective, highly repeatable, 4D-optimized, single-pattern/patch seismic data-acquisition approach with several 3D data sets was used to evaluate the feasibility of imaging changes associated with the " water alternated with gas" (WAG) stage. By incorporating noninversion-based seismic-attribute analysis, the time and cost of processing and interpreting the data were reduced. A 24-ms-thick EOR-CO 2 injection interval-using an average instantaneous frequency attribute (AIF) was targeted. Changes in amplitude response related to decrease in velocity from pore-fluid replacement within this time interval were found to be lower relative to background values than in AIF analysis. Carefully color-balanced AIF-attribute maps established the overall area affected by the injected EOR-CO2.

Fault zone identification in the eastern part of the Persian Gulf based on combined seismic attributes

NASA Astrophysics Data System (ADS)

Mirkamali, M. S.; Keshavarz FK, N.; Bakhtiari, M. R.

2013-02-01

Faults, as main pathways for fluids, play a critical role in creating regions of high porosity and permeability, in cutting cap rock and in the migration of hydrocarbons into the reservoir. Therefore, accurate identification of fault zones is very important in maximizing production from petroleum traps. Image processing and modern visualization techniques are provided for better mapping of objects of interest. In this study, the application of fault mapping in the identification of fault zones within the Mishan and Aghajari formations above the Guri base unconformity surface in the eastern part of Persian Gulf is investigated. Seismic single- and multi-trace attribute analyses are employed separately to determine faults in a vertical section, but different kinds of geological objects cannot be identified using individual attributes only. A mapping model is utilized to improve the identification of the faults, giving more accurate results. This method is based on combinations of all individual relevant attributes using a neural network system to create combined attributes, which gives an optimal view of the object of interest. Firstly, a set of relevant attributes were separately calculated on the vertical section. Then, at interpreted positions, some example training locations were manually selected in each fault and non-fault class by an interpreter. A neural network was trained on combinations of the attributes extracted at the example training locations to generate an optimized fault cube. Finally, the results of the fault and nonfault probability cube were estimated, which the neural network applied to the entire data set. The fault probability cube was obtained with higher mapping accuracy and greater contrast, and with fewer disturbances in comparison with individual attributes. The computed results of this study can support better understanding of the data, providing fault zone mapping with reliable results.

Western Rainier Seismic Zone Airborne Laser Swath Mapping

NASA Technical Reports Server (NTRS)

Harding, David J.; Haugerud, Ralph A.; Johnson, Samuel Y.; Scott, Kevin M.; Weaver, Craig S.; Martinez, Diana M.; Zeigler, John C.; Latypov, Damir

2003-01-01

Airborne laser swath mapping (ALSM) of the Puget Lowland conducted by TerraPoint LLC for the Purget Sound Lidar Concortium (PSLC), has been successful in revealing Holocene fault scarps and lendsliders hidden beneath the dense, temperate rain forest cover and in quantifying shoreline terrace uplift. Expanding the PSLC efforts, NASA-USGS collaboration is now focusing on topographic mapping of seismogenic zones adjacent to volcanois in the western Cascades range in order to assess the presence of active faulting and tectonic deformation, better define the extend of lahars and understand their flow processes, and characterize landslide occurrence. Mapping of the western Rainier zone (WRZ) was conducted by TerraPoint in late 2002, after leaf fall and before snow accumulation. The WRZ is a NNW-trending, approx. 30 km-long zone of seismicity west of Mount Rainier National Park. The Puget Lowland ALSM methods were modified to accommodate challenges posed by the steep, high relief terrian. The laser data, acquired with a density of approx. 2 pulses /sq m, was filtered to identify returns from the ground from which a bare Earth digital elevation model (DEM) was produced with a grid size of 1.8 m. The RMS elevation accuracy of the DEM in flat, unvegetated areas is approx. 10cm based on consistency between overlapping flight swaths and comparisons to ground control points. The resulting DEM substantially improves upon Shuttle Radar Topography Mission and USGS photogrammetric mapping. For example, the DEM defines the size and spatial distribution of flood erratics left by the Electron lahar and of megaclasts within the Round Pass lahar, important for characterizing the lahar hydraulics. A previously unknown lateral levee on the Round Pass lahar is also revealed. In addition, to illustrating geomorfic feature within the WRZ, future plans for laser mapping of the Saint Helens and Darrington seismic zones will be described.

Active Fault Near-Source Zones Within and Bordering the State of California for the 1997 Uniform Building Code

USGS Publications Warehouse

Petersen, M.D.; Toppozada, Tousson R.; Cao, T.; Cramer, C.H.; Reichle, M.S.; Bryant, W.A.

2000-01-01

The fault sources in the Project 97 probabilistic seismic hazard maps for the state of California were used to construct maps for defining near-source seismic coefficients, Na and Nv, incorporated in the 1997 Uniform Building Code (ICBO 1997). The near-source factors are based on the distance from a known active fault that is classified as either Type A or Type B. To determine the near-source factor, four pieces of geologic information are required: (1) recognizing a fault and determining whether or not the fault has been active during the Holocene, (2) identifying the location of the fault at or beneath the ground surface, (3) estimating the slip rate of the fault, and (4) estimating the maximum earthquake magnitude for each fault segment. This paper describes the information used to produce the fault classifications and distances.

Seismic Hazard Management in Mexico City

NASA Astrophysics Data System (ADS)

Wintergerst, L.

2007-05-01

Mexico City is one of the largest cities in the world. More than 8.5 million residents and 4.5 million floating population are in the city itself, but with the surrounding suburbs the number of people that could be affected by natural and man-made hazards rises to approximately 20 million. The main risk to the city as a whole is a large magnitude earthquake. Since there is reason to prepare for a credible seismic scenario of Mw = 8.2, which would exceed the damages caused during the 1985 earthquake (Mw = 8.1), we founded the Metropolitan Geologic Service (MGS) in 1998. The MGS has developed geologic and seismic hazard maps for the city (http:www.proteccioncivil.df.gob.mx). The maps include three separate risk maps for low height (3 stories), medium height (10 stories) and tall buildings (10 stories). The maps were prepared by using the maximum horizontal accelerations documented during the 1985 earthquake, and wave propagation modeling for buildings of different resonant periods (T = 0.0, 1.0 and 2.0 sec). In all cases, the risk zones were adjusted to include documented damage during the 1957, 1979 and 1985 earthquakes. All three maps show a high risk zone in the north-central portion of the city, elongated in a N-S direction, which corresponds with a narrow graben where the thickness of alluvial sediments is particularly large, and where wave amplification is accentuated. Preparation of these maps, and others used for planning, has been facilitated by the ongoing elaboration of a Dynamic Geographical Information System, which is based on geo-scientific information, includes all types of risks, and incorporates vulnerability models. From the risk management standpoint, we have elaborated the Permanent Contingency Plan for Mexico City, which in its Earthquakes chapter includes plans for coordination and for organizing attention to the population in the event of a seismic disaster. This Permanent Plan follows the philosophy of Descartes' Method, has 11 processes (6 main and 5 support processes), and is coordinated by Center of Control of Operations under the overall direction of the Head of Government of the Federal District. We are also working on the definition of the Basic Elements for a New Paradigm in the Prevention of Disasters, to investigate the origins, causes and effects of disaster phenomena, and to plan and implement a suitable response from the Government to better protect the population.

Seismic hazard assessment in the megacity of Blida (Algeria) and its surrounding regions using parametric-historic procedure

NASA Astrophysics Data System (ADS)

Bellalem, Fouzi; Talbi, Abdelhak; Djellit, Hamou; Ymmel, Hayet; Mobarki, Mourad

2018-03-01

The region of Blida is characterized by a relatively high seismic activity, pointed especially during the past two centuries. Indeed, it experienced a significant number of destructive earthquakes such as the earthquakes of March 2, 1825 and January 2, 1867, with intensity of X and IX, respectively. This study aims to investigate potential seismic hazard in Blida city and its surrounding regions. For this purpose, a typical seismic catalog was compiled using historical macroseismic events that occurred over a period of a few hundred years, and the recent instrumental seismicity dating back to 1900. The parametric-historic procedure introduced by Kijko and Graham (1998, 1999) was applied to assess seismic hazard in the study region. It is adapted to deal with incomplete catalogs and does not use any subjective delineation of active seismic zones. Because of the lack of recorded strong motion data, three ground prediction models have been considered, as they seem the most adapted to the seismicity of the study region. Results are presented as peak ground acceleration (PGA) seismic hazard maps, showing expected peak accelerations with 10% probability of exceedance in 50-year period. As the most significant result, hot spot regions with high PGA values are mapped. For example, a PGA of 0.44 g has been found in a small geographical area centered on Blida city.

High-resolution seismic-reflection data offshore of Dana Point, southern California borderland

USGS Publications Warehouse

Sliter, Ray W.; Ryan, Holly F.; Triezenberg, Peter J.

2010-01-01

The U.S. Geological Survey collected high-resolution shallow seismic-reflection profiles in September 2006 in the offshore area between Dana Point and San Mateo Point in southern Orange and northern San Diego Counties, California. Reflection profiles were located to image folds and reverse faults associated with the San Mateo fault zone and high-angle strike-slip faults near the shelf break (the Newport-Inglewood fault zone) and at the base of the slope. Interpretations of these data were used to update the USGS Quaternary fault database and in shaking hazard models for the State of California developed by the Working Group for California Earthquake Probabilities. This cruise was funded by the U.S. Geological Survey Coastal and Marine Catastrophic Hazards project. Seismic-reflection data were acquired aboard the R/V Sea Explorer, which is operated by the Ocean Institute at Dana Point. A SIG ELC820 minisparker seismic source and a SIG single-channel streamer were used. More than 420 km of seismic-reflection data were collected. This report includes maps of the seismic-survey sections, linked to Google Earth? software, and digital data files showing images of each transect in SEG-Y, JPEG, and TIFF formats.

Intelligent seismic risk mitigation system on structure building

NASA Astrophysics Data System (ADS)

Suryanita, R.; Maizir, H.; Yuniorto, E.; Jingga, H.

2018-01-01

Indonesia located on the Pacific Ring of Fire, is one of the highest-risk seismic zone in the world. The strong ground motion might cause catastrophic collapse of the building which leads to casualties and property damages. Therefore, it is imperative to properly design the structural response of building against seismic hazard. Seismic-resistant building design process requires structural analysis to be performed to obtain the necessary building responses. However, the structural analysis could be very difficult and time consuming. This study aims to predict the structural response includes displacement, velocity, and acceleration of multi-storey building with the fixed floor plan using Artificial Neural Network (ANN) method based on the 2010 Indonesian seismic hazard map. By varying the building height, soil condition, and seismic location in 47 cities in Indonesia, 6345 data sets were obtained and fed into the ANN model for the learning process. The trained ANN can predict the displacement, velocity, and acceleration responses with up to 96% of predicted rate. The trained ANN architecture and weight factors were later used to build a simple tool in Visual Basic program which possesses the features for prediction of structural response as mentioned previously.

Updates to building-code maps for the 2015 NEHRP recommended seismic provisions

USGS Publications Warehouse

Luco, Nicolas; Bachman, Robert; Crouse, C.B; Harris, James R.; Hooper, John D.; Kircher, Charles A.; Caldwell, Phillp; Rukstales, Kenneth S.

2015-01-01

With the 2014 update of the U.S. Geological Survey (USGS) National Seismic Hazard Model (NSHM) as a basis, the Building Seismic Safety Council (BSSC) has updated the earthquake ground motion maps in the National Earthquake Hazards Reduction Program (NEHRP) Recommended Seismic Provisions for New Buildings and Other Structures, with partial funding from the Federal Emergency Management Agency. Anticipated adoption of the updated maps into the American Society of Civil Engineers Minimum Design Loads for Building and Other Structures and the International Building and Residential Codes is underway. Relative to the ground motions in the prior edition of each of these documents, most of the updated values are within a ±20% change. The larger changes are, in most cases, due to the USGS NSHM updates, reasons for which are given in companion publications. In some cases, the larger changes are partly due to a BSSC update of the slope of the fragility curve that is used to calculate the risk-targeted ground motions, and/or the introduction by BSSC of a quantitative definition of “active faults” used to calculate deterministic ground motions.

Probabilistic Seismic Hazard Assessment of the Chiapas State (SE Mexico)

NASA Astrophysics Data System (ADS)

Rodríguez-Lomelí, Anabel Georgina; García-Mayordomo, Julián

2015-04-01

The Chiapas State, in southeastern Mexico, is a very active seismic region due to the interaction of three tectonic plates: Northamerica, Cocos and Caribe. We present a probabilistic seismic hazard assessment (PSHA) specifically performed to evaluate seismic hazard in the Chiapas state. The PSHA was based on a composited seismic catalogue homogenized to Mw and was used a logic tree procedure for the consideration of different seismogenic source models and ground motion prediction equations (GMPEs). The results were obtained in terms of peak ground acceleration as well as spectral accelerations. The earthquake catalogue was compiled from the International Seismological Center and the Servicio Sismológico Nacional de México sources. Two different seismogenic source zones (SSZ) models were devised based on a revision of the tectonics of the region and the available geomorphological and geological maps. The SSZ were finally defined by the analysis of geophysical data, resulting two main different SSZ models. The Gutenberg-Richter parameters for each SSZ were calculated from the declustered and homogenized catalogue, while the maximum expected earthquake was assessed from both the catalogue and geological criteria. Several worldwide and regional GMPEs for subduction and crustal zones were revised. For each SSZ model we considered four possible combinations of GMPEs. Finally, hazard was calculated in terms of PGA and SA for 500-, 1000-, and 2500-years return periods for each branch of the logic tree using the CRISIS2007 software. The final hazard maps represent the mean values obtained from the two seismogenic and four attenuation models considered in the logic tree. For the three return periods analyzed, the maps locate the most hazardous areas in the Chiapas Central Pacific Zone, the Pacific Coastal Plain and in the Motagua and Polochic Fault Zone; intermediate hazard values in the Chiapas Batholith Zone and in the Strike-Slip Faults Province. The hazard decreases towards the northeast across the Reverse Faults Province and up to Yucatan Platform, where the lowest values are reached. We also produced uniform hazard spectra (UHS) for the three main cities of Chiapas. Tapachula city presents the highest spectral accelerations, while Tuxtla Gutierrez and San Cristobal de las Casas cities show similar values. We conclude that seismic hazard in Chiapas is chiefly controlled by the subduction of the Cocos beneath Northamerica and Caribe tectonic plates, that makes the coastal areas the most hazardous. Additionally, the Motagua and Polochic Fault Zones are also important, increasing the hazard particularly in southeastern Chiapas.

Lithospheric magnetic field modelling of the African continent

NASA Astrophysics Data System (ADS)

Hemant, K.; Maus, S.

2003-04-01

New magnetic satellite missions in low-earth orbit are providing increasingly accurate maps of the lithospheric magnetic field. These maps can be used to infer the geological structure of regions hidden by Phanerozoic cover, taking into account our knowledge of crustal structure from surface geology and seismic methods. A GIS based modelling technique has been developed to model the various geological units of the continents using the UNESCO geological map of the world, supported by background geological information from various sources. Geological units of each region are assigned a susceptibility value based on laboratory values of the constituent rock types. Then, using the 3SMAC seismic crustal structure, a vertically integrated susceptibility (VIS) model is computed at each point of the region. Starting with this VIS model, the total field anomaly is computed at an altitude of 400 km and compared with the MF2 lithospheric magnetic field model derived from CHAMP data. The modelling results of the Precambrian units of the West African cratons agree well with MF2. The anomaly in the Central African cratonic region also correlates well, although part of it is unaccounted for as yet. Furthermore, the anomalies over the Tanzanian craton and surrounding region agree very well. Most of the regions around the South African cratons are hidden by Phanerozoic cover, yet the results above the Kaapvaal craton and the southern Zimbabwe craton around the Limpopo belt show good correspondence with the observed anomaly map. The results also suggest a probable extension of the Precambrian units below the sediments of younger age. In general, the lower crust is likely to be more mafic than presumed in our current understanding of Central Africa. Deviations in the magnitude of the anomalies in some regions are likely to be due to incomplete seismic information in those regions. Thus, the thickness of crustal layers derived from magnetic anomalies for these locations may help to constrain future geophysical models in the less explored regions of Africa.

VS30 – A site-characterization parameter for use in building Codes, simplified earthquake resistant design, GMPEs, and ShakeMaps

USGS Publications Warehouse

Borcherdt, Roger D.

2012-01-01

VS30, defined as the average seismic shear-wave velocity from the surface to a depth of 30 meters, has found wide-spread use as a parameter to characterize site response for simplified earthquake resistant design as implemented in building codes worldwide. VS30 , as initially introduced by the author for the US 1994 NEHRP Building Code, provides unambiguous definitions of site classes and site coefficients for site-dependent response spectra based on correlations derived from extensive borehole logging and comparative ground-motion measurement programs in California. Subsequent use of VS30 for development of strong ground motion prediction equations (GMPEs) and measurement of extensive sets of VS borehole data have confirmed the previous empirical correlations and established correlations of SVS30 with VSZ at other depths. These correlations provide closed form expressions to predict S30 V at a large number of additional sites and further justify S30 V as a parameter to characterize site response for simplified building codes, GMPEs, ShakeMap, and seismic hazard mapping.

Characterization of the Hosgri Fault Zone and adjacent structures in the offshore Santa Maria Basin, south-central California: Chapter CC of Evolution of sedimentary basins/onshore oil and gas investigations - Santa Maria province

USGS Publications Warehouse

Willingham, C. Richard; Rietman, Jan D.; Heck, Ronald G.; Lettis, William R.

2013-01-01

The Hosgri Fault Zone trends subparallel to the south-central California coast for 110 km from north of Point Estero to south of Purisima Point and forms the eastern margin of the present offshore Santa Maria Basin. Knowledge of the attributes of the Hosgri Fault Zone is important for petroleum development, seismic engineering, and environmental planning in the region. Because it lies offshore along its entire reach, our characterizations of the Hosgri Fault Zone and adjacent structures are primarily based on the analysis of over 10,000 km of common-depth-point marine seismic reflection data collected from a 5,000-km2 area of the central and eastern parts of the offshore Santa Maria Basin. We describe and illustrate the along-strike and downdip geometry of the Hosgri Fault Zone over its entire length and provide examples of interpreted seismic reflection records and a map of the structural trends of the fault zone and adjacent structures in the eastern offshore Santa Maria Basin. The seismic data are integrated with offshore well and seafloor geologic data to describe the age and seismic appearance of offshore geologic units and marker horizons. We develop a basin-wide seismic velocity model for depth conversions and map three major unconformities along the eastern offshore Santa Maria Basin. Accompanying plates include maps that are also presented as figures in the report. Appendix A provides microfossil data from selected wells and appendix B includes uninterpreted copies of the annotated seismic record sections illustrated in the chapter. Features of the Hosgri Fault Zone documented in this investigation are suggestive of both lateral and reverse slip. Characteristics indicative of lateral slip include (1) the linear to curvilinear character of the mapped trace of the fault zone, (2) changes in structural trend along and across the fault zone that diminish in magnitude toward the ends of the fault zone, (3) localized compressional and extensional structures characteristic of constraining and releasing bends and stepovers, (4) changes in the sense and magnitude of vertical separation along strike within the fault zone, and (5) changes in downdip geometry between the major traces and segments of the fault zone. Characteristics indicative of reverse slip include (1) reverse fault geometries that occur across major strands of the fault zone and (2) fault-bend folds and localized thrust faults that occur along the northern and southern reaches of the fault. Analyses of high-resolution, subbottom profiler and side-scan sonar records indicate localized Holocene activity along most of the extent of the fault zone. Collectively, these features are the basis of our characterization of the Hosgri Fault Zone as an active, 110-km-long, convergent right-oblique slip (transpressional) fault with identified northern and southern terminations. This interpretation is consistent with recently published analyses of onshore geologic data, regional tectonic kinematic models, and instrumental seismicity.

The utility of petroleum seismic exploration data in delineating structural features within salt anticlines

USGS Publications Warehouse

Stockton, S.L.; Balch, Alfred H.

1978-01-01

The Salt Valley anticline, in the Paradox Basin of southeastern Utah, is under investigation for use as a location for storage of solid nuclear waste. Delineation of thin, nonsalt interbeds within the upper reaches of the salt body is extremely important because the nature and character of any such fluid- or gas-saturated horizons would be critical to the mode of emplacement of wastes into the structure. Analysis of 50 km of conventional seismic-reflection data, in the vicinity of the anticline, indicates that mapping of thin beds at shallow depths may well be possible using a specially designed adaptation of state-of-the-art seismic oil-exploration procedures. Computer ray-trace modeling of thin beds in salt reveals that the frequency and spatial resolution required to map the details of interbeds at shallow depths (less than 750 m) may be on the order of 500 Hz, with surface-spread lengths of less than 350 m. Consideration should be given to the burial of sources and receivers in order to attenuate surface noise and to record the desired high frequencies. Correlation of the seismic-reflection data with available well data and surface geology reveals the complex, structurally initiated diapir, whose upward flow was maintained by rapid contemporaneous deposition of continental clastic sediments on its flanks. Severe collapse faulting near the crests of these structures has distorted the seismic response. Evidence exists, however, that intrasalt thin beds of anhydrite, dolomite, and black shale are mappable on seismic record sections either as short, discontinuous reflected events or as amplitude anomalies that result from focusing of the reflected seismic energy by the thin beds; computer modeling of the folded interbeds confirms both of these as possible causes of seismic response from within the salt diapir. Prediction of the seismic signatures of the interbeds can be made from computer-model studies. Petroleum seismic-reflection data are unsatisfactory for mapping the thin beds because of the lack of sufficient resolution to provide direct evidence of the presence of the thin beds. However, indirect evidence, present in these data as discontinuous seismic events, suggests that two geophysical techniques designed for this specific problem would allow direct detection of the interbeds in salt. These techniques are vertical seismic profiling and shallow, short-offset, high-frequency, seismic-reflection recording.

The integration of stress, strain, and seismogenic fault data: towards more robust estimates of the earthquake potential in Italy and its surroundings

NASA Astrophysics Data System (ADS)

Caporali, Alessandro; Braitenberg, Carla; Burrato, Pierfrancesco; Carafa, Michele; Di Giovambattista, Rita; Gentili, Stefania; Mariucci, Maria Teresa; Montone, Paola; Morsut, Federico; Nicolini, Luca; Pivetta, Tommaso; Roselli, Pamela; Rossi, Giuliana; Valensise, Gian Luca; Vigano, Alfio

2016-04-01

Italy is an earthquake-prone country with a long tradition in observational seismology. For many years, the country's unique historical earthquake record has revealed fundamental properties of Italian seismicity and has been used to determine earthquake rates. Paleoseismological studies conducted over the past 20 years have shown that the length of this record - 5 to 8 centuries, depending on areas - is just a fraction of the typical recurrence interval of Italian faults - consistently larger than a millennium. Hence, so far the earthquake potential may have been significantly over- or under-estimated. Based on a clear perception of these circumstances, over the past two decades large networks and datasets describing independent aspects of the seismic cycle have been developed. INGV, OGS, some universities and local administrations have built networks that globally include nearly 500 permanent GPS/GNSS sites, routinely used to compute accurate horizontal velocity gradients reflecting the accumulation of tectonic strain. INGV developed the Italian present-day stress map, which includes over 700 datapoints based on geophysical in-situ measurements and fault plane solutions, and the Database of Individual Seismogenic Sources (DISS), a unique compilation featuring nearly 300 three-dimensional seismogenic faults over the entire nation. INGV also updates and maintains the Catalogo Parametrico dei Terremoti Italiani (CPTI) and the instrumental earthquake database ISIDe, whereas OGS operates its own seismic catalogue for northeastern Italy. We present preliminary results on the use of this wealth of homogeneously collected and updated observations of stress and strain as a source of loading/unloading of the faults listed in the DISS database. We use the geodetic strain rate - after converting it to stress rate in conjunction with the geophysical stress data of the Stress Map - to compute the Coulomb Failure Function on all fault planes described by the DISS database. This may be seen as an indicator of the rate at which the regional stress is transferred to each fault; as its sign can be positive or negative, the Coulomb Failure Function rate should ultimately indicate the rate at which every fault for which sufficient geodetic data are available is loading or unloading elastic energy. A better understanding of the relationships among geodetically-documented strains, present-day stress, active faulting and seismicity for the entire country should enable us to outline regions where the current strains explain well the known seismicity and to single out areas where stress is consistently building up but are historically quiescent. In such areas the lack of seismicity may result from a limited earthquake coupling - i.e. current strains are consumed aseismically - or from the incompleteness of the earthquake record. Our results may ultimately contribute to the assessment of time-dependent seismic hazard in Italy, thus complementing the time-independent approach used for conventional seismic hazard maps.

Development of a low cost method to estimate the seismic signature of a geothermal field from ambient seismic noise analysis, Authors: Tibuleac, I. M., J. Iovenitti, S. Pullammanapallil, D. von Seggern, F.H. Ibser, D. Shaw and H. McLahlan

NASA Astrophysics Data System (ADS)

Tibuleac, I. M.; Iovenitti, J. L.; Pullammanappallil, S. K.; von Seggern, D. H.; Ibser, H.; Shaw, D.; McLachlan, H.

2015-12-01

A new, cost effective and non-invasive exploration method using ambient seismic noise has been tested at Soda Lake, NV, with promising results. Seismic interferometry was used to extract Green's Functions (P and surface waves) from 21 days of continuous ambient seismic noise. With the advantage of S-velocity models estimated from surface waves, an ambient noise seismic reflection survey along a line (named Line 2), although with lower resolution, reproduced the results of the active survey, when the ambient seismic noise was not contaminated by strong cultural noise. Ambient noise resolution was less at depth (below 1000m) compared to the active survey. Useful information could be recovered from ambient seismic noise, including dipping features and fault locations. Processing method tests were developed, with potential to improve the virtual reflection survey results. Through innovative signal processing techniques, periods not typically analyzed with high frequency sensors were used in this study to obtain seismic velocity model information to a depth of 1.4km. New seismic parameters such as Green's Function reflection component lateral variations, waveform entropy, stochastic parameters (Correlation Length and Hurst number) and spectral frequency content extracted from active and passive surveys showed potential to indicate geothermal favorability through their correlation with high temperature anomalies, and showed potential as fault indicators, thus reducing the uncertainty in fault identification. Geothermal favorability maps along ambient seismic Line 2 were generated considering temperature, lithology and the seismic parameters investigated in this study and compared to the active Line 2 results. Pseudo-favorability maps were also generated using only the seismic parameters analyzed in this study.

Reassessment of the Seismicity and seismic hazards of Libya

NASA Astrophysics Data System (ADS)

Ben Suleman, A.; Elmeladi, A.

2009-04-01

The tectonic evolution of Libya, located at the northern extreme of the African continent, has yielded a complex crustal structure that is composed of a series of basins and uplifts. The present day deformation of Libya is the result of the Eurasia-Africa continental collision. At the end of the year 2005, The Libyan National Seismological Network was established to monitor local, regional and teleseismic activities, as well as to provide high quality data for research projects both locally and on the regional and global scale. This study aims to discuss the seismicity of Libya by using the new data from the Libyan national seismological network and to focus on the seismic hazards. At first glance the seismic activity map shows dominant trends of seismicity with most of the seismic activity concentrated along the northern coastal areas. Four major seismic trends were quite noticeable. A first trend is a NW-SE direction coinciding with the eastern boarder of the Hun Graben. A second trend is also a NW-SE direction in the offshore area and might be a continuation of this trend. The other two trends were located in the western Gulf of Sirt and Cyrenaica platform. The rest of seismicity is diffuse either offshore or in land, with no good correlation with well-mapped faults. Detailed investigations of the Libyan seismicity indicates that the Libya has experienced earthquakes of varying magnitudes and that there is definitely a certain amount of seismic risk involved in engineering projects, particularly in the northern regions. Detailed investigation of the distribution of the Libyan earthquakes in space and time along with all other geological considerations suggested the classification of the country into four seismic zones with the Hun graben zone being the most seismically active zone.

Seismic Ecology

NASA Astrophysics Data System (ADS)

Seleznev, V. S.; Soloviev, V. M.; Emanov, A. F.

The paper is devoted to researches of influence of seismic actions for industrial and civil buildings and people. The seismic actions bring influence directly on the people (vibration actions, force shocks at earthquakes) or indirectly through various build- ings and the constructions and can be strong (be felt by people) and weak (be fixed by sensing devices). The great number of work is devoted to influence of violent seismic actions (first of all of earthquakes) on people and various constructions. This work is devoted to study weak, but long seismic actions on various buildings and people. There is a need to take into account seismic oscillations, acting on the territory, at construction of various buildings on urbanized territories. Essential influence, except for violent earthquakes, man-caused seismic actions: the explosions, seismic noise, emitted by plant facilities and moving transport, radiation from high-rise buildings and constructions under action of a wind, etc. can exert. Materials on increase of man- caused seismicity in a number of regions in Russia, which earlier were not seismic, are presented in the paper. Along with maps of seismic microzoning maps to be built indicating a variation of amplitude spectra of seismic noise within day, months, years. The presence of an information about amplitudes and frequencies of oscillations from possible earthquakes and man-caused oscillations in concrete regions allows carry- ing out soundly designing and construction of industrial and civil housing projects. The construction of buildings even in not seismically dangerous regions, which have one from resonance frequencies coincident on magnitude to frequency of oscillations, emitted in this place by man-caused objects, can end in failure of these buildings and heaviest consequences for the people. The practical examples of detail of engineering- seismological investigation of large industrial and civil housing projects of Siberia territory (hydro power stations, bridges, constructions, etc.) are given.

Seismic Hazard and Risk Assessments for Beijing-Tianjin-Tangshan, China, Area

USGS Publications Warehouse

Xie, F.; Wang, Z.; Liu, J.

2011-01-01

Seismic hazard and risk in the Beijing-Tianjin-Tangshan, China, area were estimated from 500-year intensity observations. First, we digitized the intensity observations (maps) using ArcGIS with a cell size of 0.1 ?? 0.1??. Second, we performed a statistical analysis on the digitized intensity data, determined an average b value (0.39), and derived the intensity-frequency relationship (hazard curve) for each cell. Finally, based on a Poisson model for earthquake occurrence, we calculated seismic risk in terms of a probability of I ??? 7, 8, or 9 in 50 years. We also calculated the corresponding 10 percent probability of exceedance of these intensities in 50 years. The advantages of assessing seismic hazard and risk from intensity records are that (1) fewer assumptions (i. e., earthquake source and ground motion attenuation) are made, and (2) site-effect is included. Our study shows that the area has high seismic hazard and risk. Our study also suggests that current design peak ground acceleration or intensity for the area may not be adequate. ?? 2010 Birkh??user / Springer Basel AG.

Effects of magnitude, depth, and time on cellular seismology forecasts

NASA Astrophysics Data System (ADS)

Fisher, Steven Wolf

This study finds that, in most cases analyzed to date, past seismicity tends to delineate zones where future earthquakes are likely to occur. Network seismicity catalogs for the New Madrid Seismic Zone (NMSZ), Australia (AUS), California (CA), and Alaska (AK) are analyzed using modified versions of the Cellular Seismology (CS) method of Kafka (2002, 2007). The percentage of later occurring earthquakes located near earlier occurring earthquakes typically exceeds the expected percentage for randomly distributed later occurring earthquakes, and the specific percentage is influenced by several variables, including magnitude, depth, time, and tectonic setting. At 33% map area coverage, hit percents are typically 85-95% in the NMSZ, 50-60% in AUS, 75-85% in CA, and 75-85% in AK. Statistical significance testing is performed on trials analyzing the same variables so that the overall regions can be compared, although some tests are inconclusive due to the small number of earthquake sample sizes. These results offer useful insights into understanding the capabilities and limits of CS studies, which can provide guidance for improving the seismicity-based components of seismic hazard assessments.

Lithology-derived structure classification from the joint interpretation of magnetotelluric and seismic models

USGS Publications Warehouse

Bedrosian, P.A.; Maercklin, N.; Weckmann, U.; Bartov, Y.; Ryberg, T.; Ritter, O.

2007-01-01

Magnetotelluric and seismic methods provide complementary information about the resistivity and velocity structure of the subsurface on similar scales and resolutions. No global relation, however, exists between these parameters, and correlations are often valid for only a limited target area. Independently derived inverse models from these methods can be combined using a classification approach to map geologic structure. The method employed is based solely on the statistical correlation of physical properties in a joint parameter space and is independent of theoretical or empirical relations linking electrical and seismic parameters. Regions of high correlation (classes) between resistivity and velocity can in turn be mapped back and re-examined in depth section. The spatial distribution of these classes, and the boundaries between them, provide structural information not evident in the individual models. This method is applied to a 10 km long profile crossing the Dead Sea Transform in Jordan. Several prominent classes are identified with specific lithologies in accordance with local geology. An abrupt change in lithology across the fault, together with vertical uplift of the basement suggest the fault is sub-vertical within the upper crust. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

Constraining the crustal root geometry beneath Northern Morocco

NASA Astrophysics Data System (ADS)

Díaz, J.; Gil, A.; Carbonell, R.; Gallart, J.; Harnafi, M.

2016-10-01

Consistent constraints of an over-thickened crust beneath the Rif Cordillera (N. Morocco) are inferred from analyses of recently acquired seismic datasets including controlled source wide-angle reflections and receiver functions from teleseismic events. Offline arrivals of Moho-reflected phases recorded in RIFSIS project provide estimations of the crustal thicknesses in 3D. Additional constraints on the onshore-offshore transition are inferred from shots in a coeval experiment in the Alboran Sea recorded at land stations in northern Morocco. A regional crustal thickness map is computed from all these results. In parallel, we use natural seismicity data collected throughout TopoIberia and PICASSO experiments, and from a new RIFSIS deployment, to obtain receiver functions and explore the crustal thickness variations with a H-κ grid-search approach. This larger dataset provides better resolution constraints and reveals a number of abrupt crustal changes. A gridded surface is built up by interpolating the Moho depths inferred for each seismic station, then compared with the map from controlled source experiments. A remarkably consistent image is observed in both maps, derived from completely independent data and methods. Both approaches document a large crustal root, exceeding 50 km depth in the central part of the Rif, in contrast with the rather small topographic elevations. This large crustal thickness, consistent with the available Bouguer anomaly data, favors models proposing that the high velocity slab imaged by seismic tomography beneath the Alboran Sea is still attached to the lithosphere beneath the Rif, hence pulling down the lithosphere and thickening the crust. The thickened area corresponds to a quiet seismic zone located between the western Morocco arcuate seismic zone, the deep seismicity area beneath western Alboran Sea and the superficial seismicity in Alhoceima area. Therefore, the presence of a crustal root seems to play also a major role in the seismicity distribution in northern Morocco.

The Pollino Seismic Sequence: Activated Graben Structures in a Seismic Gap

NASA Astrophysics Data System (ADS)

Rößler, Dirk; Passarelli, Luigi; Govoni, Aladino; Bindi, Dino; Cesca, Simone; Hainzl, Sebatian; Maccaferri, Francesco; Rivalta, Eleonora; Woith, Heiko; Dahm, Torsten

2015-04-01

The Mercure Basin (MB) and the Castrovillari Fault (CF) in the Pollino range (Southern Apennines, Italy) represent one of the most prominent seismic gaps in the Italian seismic catalogue, with no M>5.5 earthquakes during the last centuries. In historical times several swarm-like seismic sequences occurred in the area including two intense swarms within the past two decades. The most energetic one started in 2010 and has been still active in 2014. The seismicity culminated in autumn 2012 with a M=5 event on 25 October. The range hosts a number of opposing normal faults forming a graben-like structure. Their rheology and their interactions are unclear. Current debates include the potential of the MB and the CF to host large earthquakes and the style of deformation. Understanding the seismicity and the behaviour of the faults is necessary to assess the tectonics and the seismic hazard. The GFZ German Research Centre for Geosciences and INGV, Italy, have jointly monitored the ongoing seismicity using a small-aperture seismic array, integrated in a temporary seismic network. Based on this installation, we located more than 16,000 local earthquakes that occurred between November 2012 and September 2014. Here we investigate quantitatively all the phases of the seismic sequence starting from January 2010. Event locations along with moment tensor inversion constrain spatially the structures activated by the swarm and the migration pattern of the seismicity. The seismicity forms clusters concentrated within the southern part of the MB and along the Pollino Fault linking MB and CF. Most earthquakes are confined to the upper 10 km of the crust in an area of ~15x15 km2. However, sparse seismicity at depths between 15 and 20 km and moderate seismicity further north with deepening hypocenters also exist. In contrast, the CF appears aseismic; only the northern part has experienced micro-seismicity. The spatial distribution is however more complex than the major tectonic structures mapped for the area. Consistent with mapped faults, the seismicity interested both eastwards and westwards dipping normal faults that define the geometry of seismically active graben-like structures. At least one cluster shows an additional spatio-temporal migration with spreading hypocentres similar to other swarm areas with fluid-triggering mechanisms. The static Coulomb stress change transferred by the largest shock onto the swarm area and on the CF cannot explain the observed high seismicity rate. We study the evolution of the frequency-size distribution of the events and the seismicity rate changes. We find that the majority of the earthquakes cannot be justified as aftershocks (directly related to the tectonics or to earthquake-earthquake interaction) and are best explained by an additional forcing active over the entire sequence. Our findings are consistent with the action of fluids (e.g. pore-pressure diffusion) triggering seismicity on pre-loaded faults. Additional aseismic release of tectonic strain by transient, slow slip is also consistent with our analysis. Analysis of deformation time series may clarify this point in future studies.

High-resolution mapping based on an Unmanned Aerial Vehicle (UAV) to capture paleoseismic offsets along the Altyn-Tagh fault, China.

PubMed

Gao, Mingxing; Xu, Xiwei; Klinger, Yann; van der Woerd, Jerome; Tapponnier, Paul

2017-08-15

The recent dramatic increase in millimeter- to centimeter- resolution topographic datasets obtained via multi-view photogrammetry raises the possibility of mapping detailed offset geomorphology and constraining the spatial characteristics of active faults. Here, for the first time, we applied this new method to acquire high-resolution imagery and generate topographic data along the Altyn Tagh fault, which is located in a remote high elevation area and shows preserved ancient earthquake surface ruptures. A digital elevation model (DEM) with a resolution of 0.065 m and an orthophoto with a resolution of 0.016 m were generated from these images. We identified piercing markers and reconstructed offsets based on both the orthoimage and the topography. The high-resolution UAV data were used to accurately measure the recent seismic offset. We obtained the recent offset of 7 ± 1 m. Combined with the high resolution satellite image, we measured cumulative offsets of 15 ± 2 m, 20 ± 2 m, 30 ± 2 m, which may be due to multiple paleo-earthquakes. Therefore, UAV mapping can provide fine-scale data for the assessment of the seismic hazards.

Application of a time probabilistic approach to seismic landslide hazard estimates in Iran

NASA Astrophysics Data System (ADS)

Rajabi, A. M.; Del Gaudio, V.; Capolongo, D.; Khamehchiyan, M.; Mahdavifar, M. R.

2009-04-01

Iran is a country located in a tectonic active belt and is prone to earthquake and related phenomena. In the recent years, several earthquakes caused many fatalities and damages to facilities, e.g. the Manjil (1990), Avaj (2002), Bam (2003) and Firuzabad-e-Kojur (2004) earthquakes. These earthquakes generated many landslides. For instance, catastrophic landslides triggered by the Manjil Earthquake (Ms = 7.7) in 1990 buried the village of Fatalak, killed more than 130 peoples and cut many important road and other lifelines, resulting in major economic disruption. In general, earthquakes in Iran have been concentrated in two major zones with different seismicity characteristics: one is the region of Alborz and Central Iran and the other is the Zagros Orogenic Belt. Understanding where seismically induced landslides are most likely to occur is crucial in reducing property damage and loss of life in future earthquakes. For this purpose a time probabilistic approach for earthquake-induced landslide hazard at regional scale, proposed by Del Gaudio et al. (2003), has been applied to the whole Iranian territory to provide the basis of hazard estimates. This method consists in evaluating the recurrence of seismically induced slope failure conditions inferred from the Newmark's model. First, by adopting Arias Intensity to quantify seismic shaking and using different Arias attenuation relations for Alborz - Central Iran and Zagros regions, well-established methods of seismic hazard assessment, based on the Cornell (1968) method, were employed to obtain the occurrence probabilities for different levels of seismic shaking in a time interval of interest (50 year). Then, following Jibson (1998), empirical formulae specifically developed for Alborz - Central Iran and Zagros, were used to represent, according to the Newmark's model, the relation linking Newmark's displacement Dn to Arias intensity Ia and to slope critical acceleration ac. These formulae were employed to evaluate the slope critical acceleration (Ac)x for which a prefixed probability exists that seismic shaking would result in a Dn value equal to a threshold x whose exceedence would cause landslide triggering. The obtained ac values represent the minimum slope resistance required to keep the probability of seismic-landslide triggering within the prefixed value. In particular we calculated the spatial distribution of (Ac)x for x thresholds of 10 and 2 cm in order to represent triggering conditions for coherent slides (e.g., slumps, block slides, slow earth flows) and disrupted slides (e.g., rock falls, rock slides, rock avalanches), respectively. Then we produced a probabilistic national map that shows the spatial distribution of (Ac)10 and (Ac)2, for a 10% probability of exceedence in 50 year, which is a significant level of hazard equal to that commonly used for building codes. The spatial distribution of the calculated (Ac)xvalues can be compared with the in situ actual ac values of specific slopes to estimate whether these slopes have a significant probability of failing under seismic action in the future. As example of possible application of this kind of time probabilistic map to hazard estimates, we compared the values obtained for the Manjil region with a GIS map providing spatial distribution of estimated ac values in the same region. The spatial distribution of slopes characterized by ac < (Ac)10 was then compared with the spatial distribution of the major landslides of coherent type triggered by the Manjil earthquake. This comparison provides indications on potential, problems and limits of the experimented approach for the study area. References Cornell, C.A., 1968: Engineering seismic risk analysis, Bull. Seism. Soc. Am., 58, 1583-1606. Del Gaudio V., Wasowski J., & Pierri P., 2003: An approach to time probabilistic evaluation of seismically-induced landslide hazard. Bull Seism. Soc. Am., 93, 557-569. Jibson, R.W., E.L. Harp and J.A. Michael, 1998: A method for producing digital probabilistic seismic landslide hazard maps: an example from the Los Angeles, California, area, U.S. Geological Survey Open-File Report 98-113, Golden, Colorado, 17 pp.

Quantifying Coseismic Normal Fault Rupture at the Seafloor: The 2004 Les Saintes Earthquake Along the Roseau Fault (French Antilles)

NASA Astrophysics Data System (ADS)

Olive, J. A. L.; Escartin, J.; Leclerc, F.; Garcia, R.; Gracias, N.; Odemar Science Party, T.

2016-12-01

While >70% of Earth's seismicity is submarine, almost all observations of earthquake-related ruptures and surface deformation are restricted to subaerial environments. Such observations are critical for understanding fault behavior and associated hazards (including tsunamis), but are not routinely conducted at the seafloor due to obvious constraints. During the 2013 ODEMAR cruise we used autonomous and remotely operated vehicles to map the Roseau normal Fault (Lesser Antilles), source of the 2004 Mw6.3 earthquake and associated tsunami (<3.5m run-up). These vehicles acquired acoustic (multibeam bathymetry) and optical data (video and electronic images) spanning from regional (>1 km) to outcrop (<1 m) scales. These high-resolution submarine observations, analogous to those routinely conducted subaerially, rely on advanced image and video processing techniques, such as mosaicking and structure-from-motion (SFM). We identify sub-vertical fault slip planes along the Roseau scarp, displaying coseismic deformation structures undoubtedly due to the 2004 event. First, video mosaicking allows us to identify the freshly exposed fault plane at the base of one of these scarps. A maximum vertical coseismic displacement of 0.9 m can be measured from the video-derived terrain models and the texture-mapped imagery, which have better resolution than any available acoustic systems (<10 cm). Second, seafloor photomosaics allow us to identify and map both additional sub-vertical fault scarps, and cracks and fissures at their base, recording hangingwall damage from the same event. These observations provide critical parameters to understand the seismic cycle and long-term seismic behavior of this submarine fault. Our work demonstrates the feasibility of extensive, high-resolution underwater surveys using underwater vehicles and novel imaging techniques, thereby opening new possibilities to study recent seafloor changes associated with tectonic, volcanic, or hydrothermal activity.

The population in China’s earthquake-prone areas has increased by over 32 million along with rapid urbanization

NASA Astrophysics Data System (ADS)

He, Chunyang; Huang, Qingxu; Dou, Yinyin; Tu, Wei; Liu, Jifu

2016-07-01

Accurate assessments of the population exposed to seismic hazard are crucial in seismic risk mapping. Recent rapid urbanization in China has resulted in substantial changes in the size and structure of the population exposed to seismic hazard. Using the latest population census data and seismic maps, this work investigated spatiotemporal changes in the exposure of the population in the most seismically hazardous areas (MSHAs) in China from 1990 to 2010. In the context of rapid urbanization and massive rural-to-urban migration, nearly one-tenth of the Chinese population in 2010 lived in MSHAs. From 1990 to 2010, the MSHA population increased by 32.53 million at a significantly higher rate of change (33.6%) than the national average rate (17.7%). The elderly population in MSHAs increased by 81.4%, which is much higher than the group’s national growth rate of 58.9%. Greater attention should be paid to the demographic changes in earthquake-prone areas in China.

Seismic expression of Red Fork channels in Major and Kay Counties, Oklahoma

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

Hanoch, C.A.

1987-08-01

This paper investigates the application of regional seismic to exploration and development Red Fork sands of the Cherokee Group, in Major and Kay Counties, Oklahoma. A computer-aided exploration system (CAEX) was used to justify the subtle seismic expressions with the geological interpretation. Modeling shows that the low-velocity shales are the anomalous rock in the Cherokee package, which is most represented by siltstone and thin sands. Because the Red Fork channel sands were incised into or deposited with laterally time-equivalent siltstones, no strong reflection coefficient is associated with the top of the sands. The objective sands become a seismic anomaly onlymore » when they cut into and replace a low-velocity shale. This knowledge allows mapping the channel thickness by interpreting the shale thickness from seismic data. A group shoot line in Major County, Oklahoma, has been tied to the geologic control, and the channel thicknesses have been interpreted assuming a detectable vertical resolution of 10 ft. A personal computer-based geophysical work station is used to construct velocity logs representative of the geology to produce forward-modeled synthetic seismic sections, and to display, in color, the seismic trace attributes. These synthetic sections are used as tools to compare with and interpret the seismic line and to evaluate the interpretative value of lowest cost, lesser quality data versus reprocessing or new data acquisition.« less

Relationship between the upper mantle high velocity seismic lid and the continental lithosphere

NASA Astrophysics Data System (ADS)

Priestley, Keith; Tilmann, Frederik

2009-04-01

The lithosphere-asthenosphere boundary corresponds to the base of the "rigid" plates - the depth at which heat transport changes from advection in the convecting deeper upper mantle to conduction in the shallow upper mantle. Although this boundary is a fundamental feature of the Earth, mapping it has been difficult because it does not correspond to a sharp change in temperature or composition. Various definitions of the lithosphere and asthenosphere are based on the analysis of different types of geophysical and geological observations. The depth to the lithosphere-asthenosphere boundary determined from these different observations often shows little agreement when they are applied to the same region because the geophysical and geological observations (i.e., seismic velocity, strain rate, electrical resistivity, chemical depletion, etc.) are proxies for the change in rheological properties rather than a direct measure of the rheological properties. In this paper, we focus on the seismic mapping of the upper mantle high velocity lid and low velocity zone and its relationship to the lithosphere and asthenosphere. We have two goals: (a) to examine the differences in how teleseismic body-wave travel-time tomography and surface-wave tomography image upper mantle seismic structure; and (b) to summarise how upper mantle seismic velocity structure can be related to the structure of the lithosphere and asthenosphere. Surface-wave tomography provides reasonably good depth resolution, especially when higher modes are included in the analysis, but lateral resolution is limited by the horizontal wavelength of the long-period surface waves used to constrain upper mantle velocity structure. Teleseismic body-wave tomography has poor depth resolution in the upper mantle, particularly when no strong lateral contrasts are present. If station terms are used, features with large lateral extent and gradual boundaries are attenuated in the tomographic image. Body-wave models are not useful in mapping the thickness of the high velocity upper mantle lid because this type of analysis often determines wave speed perturbations from an unknown horizontal average and not absolute velocities. Thus, any feature which extends laterally across the whole region beneath a seismic network becomes invisible in the teleseismic body-wave tomographic image. We compare surface-wave and body-wave tomographic results using southern Africa as an example. Surface-wave tomographic images for southern Africa show a strong, high velocity upper mantle lid confined to depths shallower than ~ 200 km, whereas body-wave tomographic images show weak high velocity in the upper mantle extending to depths of ~ 300 km or more. However, synthetic tests show that these results are not contradictory. The absolute seismic velocity structure of the upper mantle provided by surface wave analysis can be used to map the thermal lithosphere. Priestley and McKenzie (Priestley, K., McKenzie, D., 2006. The thermal structure of the lithosphere from shear wave velocities. Earth and Planetary Science Letters 244, 285-301.) derive an empirical relationship between shear wave velocity and temperature. This relationship is used to obtain temperature profiles from the surface-wave tomographic models of the continental mantle. The base of the lithosphere is shown by a change in the gradient of the temperature profiles indicative of the depth where the mode of heat transport changes from conduction to advection. Comparisons of the geotherms determined from the conversion of surface-wave wave speeds to temperatures with upper mantle nodule-derived geotherms demonstrate that estimates of lithospheric thickness from Vs and from the nodule mineralogy agree to within about 25 km. The lithospheric thickness map for Africa derived from the surface-wave tomographic results shows that thick lithosphere underlies most of the Archean crust in Africa. The distribution of diamondiferous kimberlites provides an independent estimate of where thick lithosphere exists. Diamondiferous kimberlites generally occur where the lower part of the thermal lithosphere as indicated by seismology is in the diamond stability field.

Present coupling along the Peruvian subduction asperity that devastated Lima while breaking during the 1746 earthquake

NASA Astrophysics Data System (ADS)

Cavalié, O.; Chlieh, M.; Villegas Lanza, J. C.

2016-12-01

Subduction zone are particularly prone to generating large earthquakes due to its wide lateral extension. In order to understand where, and possibly when, large earthquakes will occur, interseismic deformation observation is a key information because it allows to map asperities that accumulate stress on the plate interface. South American subduction is one of the longest worldwide, running all along the west coast of the continent. Combined with the relatively fast convergence rate between the Nazca plate and the South American continent, Chile and Peru experience regularly M>7.5 earthquakes. In this study, we focused on the Peruvian subduction margin and more precisely on the Central segment containing Lima where the seismic risk is the highest in the country due the large population that lives in the Peruvian capital. On the Central segment (10°S and 15°S), we used over 50 GPS interseismic measurements from campaign and continuous sites, as well as InSAR data to map coupling along the subduction interface. GPS data come from the Peruvian GPS network and InSAR data are from the Envisat satellite. We selected two tracks covering the central segment (including Lima) and with enough SAR image acquisitions between 2003 and 2010 to get a robust deformation estimation. GPS and InSAR data show a consistent tectonic signal with a maximum of surface displacement by the coast: the maximum horizontal velocities from GPS is about 20 mm and InSAR finds 12-13 mm in the LOS component. In addition, InSAR reveals lateral variations along the coast: the maximum motion is measured around Lima (11°S) and fades on either side. By inverting the geodetic data, we were able to map the coupling along the segment. It results in a main asperity where interseismic stress is loading. However, compared the previous published models based on GPS only, the coupling in the central segment seems more heterogeneous. Finally, we compared the deficit of seismic moment accumulating in the interseismic period with the long-term seismicity. Based on the instrumental and historical seismicity, and the present seismic coupling, a M>8.8 earthquake is expected before the end of the century. However, the actual magnitude relies on how much aseismic slip, that has not been measured during the geodesy period (i.e since 2003) occurred.

Present coupling along the Peruvian subduction asperity that devastated Lima while breaking during the 1746 earthquake

NASA Astrophysics Data System (ADS)

Cavalié, O.; Chlieh, M.; Villegas Lanza, J. C.

2017-12-01

Subduction zone are particularly prone to generating large earthquakes due to its wide lateral extension. In order to understand where, and possibly when, large earthquakes will occur, interseismic deformation observation is a key information because it allows to map asperities that accumulate stress on the plate interface. South American subduction is one of the longest worldwide, running all along the west coast of the continent. Combined with the relatively fast convergence rate between the Nazca plate and the South American continent, Chile and Peru experience regularly M>7.5 earthquakes. In this study, we focused on the Peruvian subduction margin and more precisely on the Central segment containing Lima where the seismic risk is the highest in the country due the large population that lives in the Peruvian capital. On the Central segment (10°S and 15°S), we used over 50 GPS interseismic measurements from campaign and continuous sites, as well as InSAR data to map coupling along the subduction interface. GPS data come from the Peruvian GPS network and InSAR data are from the Envisat satellite. We selected two tracks covering the central segment (including Lima) and with enough SAR image acquisitions between 2003 and 2010 to get a robust deformation estimation. GPS and InSAR data show a consistent tectonic signal with a maximum of surface displacement by the coast: the maximum horizontal velocities from GPS is about 20 mm and InSAR finds 12-13 mm in the LOS component. In addition, InSAR reveals lateral variations along the coast: the maximum motion is measured around Lima (11°S) and fades on either side. By inverting the geodetic data, we were able to map the coupling along the segment. It results in a main asperity where interseismic stress is loading. However, compared the previous published models based on GPS only, the coupling in the central segment seems more heterogeneous. Finally, we compared the deficit of seismic moment accumulating in the interseismic period with the long-term seismicity. Based on the instrumental and historical seismicity, and the present seismic coupling, a M>8.8 earthquake is expected before the end of the century. However, the actual magnitude relies on how much aseismic slip, that has not been measured during the geodesy period (i.e since 2003) occurred.

Using CyberShake Workflows to Manage Big Seismic Hazard Data on Large-Scale Open-Science HPC Resources

NASA Astrophysics Data System (ADS)

Callaghan, S.; Maechling, P. J.; Juve, G.; Vahi, K.; Deelman, E.; Jordan, T. H.

2015-12-01

The CyberShake computational platform, developed by the Southern California Earthquake Center (SCEC), is an integrated collection of scientific software and middleware that performs 3D physics-based probabilistic seismic hazard analysis (PSHA) for Southern California. CyberShake integrates large-scale and high-throughput research codes to produce probabilistic seismic hazard curves for individual locations of interest and hazard maps for an entire region. A recent CyberShake calculation produced about 500,000 two-component seismograms for each of 336 locations, resulting in over 300 million synthetic seismograms in a Los Angeles-area probabilistic seismic hazard model. CyberShake calculations require a series of scientific software programs. Early computational stages produce data used as inputs by later stages, so we describe CyberShake calculations using a workflow definition language. Scientific workflow tools automate and manage the input and output data and enable remote job execution on large-scale HPC systems. To satisfy the requests of broad impact users of CyberShake data, such as seismologists, utility companies, and building code engineers, we successfully completed CyberShake Study 15.4 in April and May 2015, calculating a 1 Hz urban seismic hazard map for Los Angeles. We distributed the calculation between the NSF Track 1 system NCSA Blue Waters, the DOE Leadership-class system OLCF Titan, and USC's Center for High Performance Computing. This study ran for over 5 weeks, burning about 1.1 million node-hours and producing over half a petabyte of data. The CyberShake Study 15.4 results doubled the maximum simulated seismic frequency from 0.5 Hz to 1.0 Hz as compared to previous studies, representing a factor of 16 increase in computational complexity. We will describe how our workflow tools supported splitting the calculation across multiple systems. We will explain how we modified CyberShake software components, including GPU implementations and migrating from file-based communication to MPI messaging, to greatly reduce the I/O demands and node-hour requirements of CyberShake. We will also present performance metrics from CyberShake Study 15.4, and discuss challenges that producers of Big Data on open-science HPC resources face moving forward.

The Messinian evaporites in the Levant Basin: lithology, deformation and its evolution

NASA Astrophysics Data System (ADS)

Feng, Ye; Steinberg, Josh; Reshef, Moshe

2017-04-01

The lithological composition of the Messinian evaporite in the Levant Basin remains controversial and salt deformation mechanisms are still not fully understood, due to the lack of high resolution 3D depth seismic data and well logs that record the entire evaporite sequence. We demonstrate how 3D Pre-stack depth migration (PSDM) and intra-salt tomography can lead to improved salt imaging. Using 3D PSDM seismic data with great coverage and deepwater well log data from recently drilled boreholes, we reveal intra-salt reflective units associated with thin clastic layers and a seismic transparent background consisting of uniform pure halite. Structural maps of all internal reflectors are generated for stratigraphy and attributes analysis. High amplitude fan structures in the lowermost intra-salt reflector are observed, which may indicate the source of the clastic formation during the Messinian Salinity Crisis (MSC). The Messinian evaporite in the Levant Basin comprises six units; the uppermost unit thickens towards the northwest, whereas the other units are uniform in thickness. The top of salt (TS) horizon is relatively horizontal, while all other intra-salt reflectors and base of salt (BS) dip towards the northwest. Different seismic attributes are used for identification of intra-salt deformation patterns. Maximum curvature maps show NW-striking thrust faults on the TS and upper intra-salt units, and dip azimuth maps are used to show different fold orientations between the TS and intra-salt units, which indicate a two-phase deformation mechanism: basin NW tilting as syn-depositional phase and NNE spreading of Plio-Pleistocene overburden as post-depositional phase. RMS amplitude maps are used to identify a channelized system on the TS. An evaporite evolution model during the MSC of the Levant Basin is therefore established based on all the observations. Finally the mechanical properties of the salts will be utilized to explore salt deformation in the Levant Basin. Feng, Y. E., & Reshef, M. (2016). The Eastern Mediterranean Messinian salt-depth imaging and velocity analysis considerations. Petroleum Geoscience, 22(4), 2-19. doi:http://dx.doi.org/10.1144/petgeo2015-088 Feng, Y. E., Yankelzon, A., Steinberg, J., & Reshef, M. (2016). Lithology and characteristics of the Messinian evaporite sequence of the deep Levant Basin, eastern Mediterranean. Marine Geology, 376, 118-131. doi:http://dx.doi.org/10.1016/j.margeo.2016.04.004

Introducing ShakeMap to potential users in Puerto Rico using scenarios of damaging historical and probable earthquakes

NASA Astrophysics Data System (ADS)

Huerfano, V. A.; Cua, G.; von Hillebrandt, C.; Saffar, A.

2007-12-01

The island of Puerto Rico has a long history of damaging earthquakes. Major earthquakes from off-shore sources have affected Puerto Rico in 1520, 1615, 1670, 1751, 1787, 1867, and 1918 (Mueller et al, 2003; PRSN Catalogue). Recent trenching has also yielded evidence of possible M7.0 events inland (Prentice, 2000). The high seismic hazard, large population, high tsunami potential and relatively poor construction practice can result in a potentially devastating combination. Efficient emergency response in event of a large earthquake will be crucial to minimizing the loss of life and disruption of lifeline systems in Puerto Rico. The ShakeMap system (Wald et al, 2004) developed by the USGS to rapidly display and disseminate information about the geographical distribution of ground shaking (and hence potential damage) following a large earthquake has proven to be a vital tool for post earthquake emergency response efforts, and is being adopted/emulated in various seismically active regions worldwide. Implementing a robust ShakeMap system is among the top priorities of the Puerto Rico Seismic Network. However, the ultimate effectiveness of ShakeMap in post- earthquake response depends not only on its rapid availability, but also on the effective use of the information it provides. We developed ShakeMap scenarios of a suite of damaging historical and probable earthquakes that severely impact San Juan, Ponce, and Mayagüez, the 3 largest cities in Puerto Rico. Earthquake source parameters were obtained from McCann and Mercado (1998); and Huérfano (2004). For historical earthquakes that generated tsunamis, tsunami inundation maps were generated using the TIME method (Shuto, 1991). The ShakeMap ground shaking maps were presented to local and regional governmental and emergency response agencies at the 2007 Annual conference of the Puerto Rico Emergency Management and Disaster Administration in San Juan, PR, and at numerous other emergency management talks and training sessions. Economic losses are estimated using the ShakeMap scenario ground motions (Saffar, 2007). The calibration tasks necessary in generating these scenarios (developing Vs30 maps, attenuation relationships) complement the on-going efforts of the Puerto Rico Seismic Network to generate ShakeMaps in real-time.

Fine-scale delineation of the location of and relative ground shaking within the San Andreas Fault zone at San Andreas Lake, San Mateo County, California

USGS Publications Warehouse

Catchings, R.D.; Rymer, M.J.; Goldman, M.R.; Prentice, C.S.; Sickler, R.R.

2013-01-01

The San Francisco Public Utilities Commission is seismically retrofitting the water delivery system at San Andreas Lake, San Mateo County, California, where the reservoir intake system crosses the San Andreas Fault (SAF). The near-surface fault location and geometry are important considerations in the retrofit effort. Because the SAF trends through highly distorted Franciscan mélange and beneath much of the reservoir, the exact trace of the 1906 surface rupture is difficult to determine from surface mapping at San Andreas Lake. Based on surface mapping, it also is unclear if there are additional fault splays that extend northeast or southwest of the main surface rupture. To better understand the fault structure at San Andreas Lake, the U.S. Geological Survey acquired a series of seismic imaging profiles across the SAF at San Andreas Lake in 2008, 2009, and 2011, when the lake level was near historical lows and the surface traces of the SAF were exposed for the first time in decades. We used multiple seismic methods to locate the main 1906 rupture zone and fault splays within about 100 meters northeast of the main rupture zone. Our seismic observations are internally consistent, and our seismic indicators of faulting generally correlate with fault locations inferred from surface mapping. We also tested the accuracy of our seismic methods by comparing our seismically located faults with surface ruptures mapped by Schussler (1906) immediately after the April 18, 1906 San Francisco earthquake of approximate magnitude 7.9; our seismically determined fault locations were highly accurate. Near the reservoir intake facility at San Andreas Lake, our seismic data indicate the main 1906 surface rupture zone consists of at least three near-surface fault traces. Movement on multiple fault traces can have appreciable engineering significance because, unlike movement on a single strike-slip fault trace, differential movement on multiple fault traces may exert compressive and extensional stresses on built structures within the fault zone. Such differential movement and resulting distortion of built structures appear to have occurred between fault traces at the gatewell near the southern end of San Andreas Lake during the 1906 San Francisco earthquake (Schussler, 1906). In addition to the three fault traces within the main 1906 surface rupture zone, our data indicate at least one additional fault trace (or zone) about 80 meters northeast of the main 1906 surface rupture zone. Because ground shaking also can damage structures, we used fault-zone guided waves to investigate ground shaking within the fault zones relative to ground shaking outside the fault zones. Peak ground velocity (PGV) measurements from our guided-wave study indicate that ground shaking is greater at each of the surface fault traces, varying with the frequency of the seismic data and the wave type (P versus S). S-wave PGV increases by as much as 5–6 times at the fault traces relative to areas outside the fault zone, and P-wave PGV increases by as much as 3–10 times. Assuming shaking increases linearly with increasing earthquake magnitude, these data suggest strong shaking may pose a significant hazard to built structures that extend across the fault traces. Similarly complex fault structures likely underlie other strike-slip faults (such as the Hayward, Calaveras, and Silver Creek Faults) that intersect structures of the water delivery system, and these fault structures similarly should be investigated.

Arctic Ocean Sedimentary Cover Structure, Based on 2D MCS Seismic Data.

NASA Astrophysics Data System (ADS)

Kireev, A.; Kaminsky, V.; Poselov, V.; Poselova, L.; Kaminsky, D.

2016-12-01

In 2016 the Russian Federation has submitted its partial revised Submission for establishment of the OLCS (outer limit of the continental shelf) in the Arctic Ocean. In order to prepare the Submission, in 2005 - 2014 the Russian organizations carried out a wide range of geological and geophysical studies, so that today over 23000 km of MCS lines and 4000 km of deep seismic sounding are accomplished. For correct time/depth conversion of seismic sections obtained with a short streamer in difficult ice conditions wide-angle reflection/refraction seismic sonobuoy soundings were used. All of these seismic data were used to refine the stratigraphy model, to identify sedimentary complexes and to estimate the total thickness of the sedimentary cover. Seismic stratigraphy model was successively determined for the Cenozoic and pre-Cenozoic parts of the sedimentary section and was based on correlation of the Russian MCS data and seismic data documented by boreholes. Cenozoic part of the sedimentary cover is based on correlation of the Russian MCS data and AWI91090 section calibrated by ACEX-2004 boreholes on the Lomonosov Ridge for Amerasia basin and by correlation of onlap contacts onto oceanic crust with defined magnetic anomalies for Eurasia basin. Pre-Cenozoic part of the sedimentary cover is based on tracing major unconformities from boreholes on the Chukchi shelf (Crackerjack, Klondike, Popcorn) to the North-Chuckchi Trough and further to the Mendeleev Rise as well as to the Vilkitsky Trough and the adjacent Podvodnikov Basin. Six main unconformities were traced: regional unconformity (RU), Eocene unconformity (EoU) (for Eurasia basin only), post-Campanian unconformity (pCU), Brookian (BU - base of the Lower Brookian unit), Lower Cretaceous (LCU) and Jurassic (JU - top of the Upper Ellesmerian unit). The final step in our research was to generalize all seismic surveys (top of acoustic basement correlation data) and bathymetry data in the sedimentary cover thickness map of the Arctic Ocean and adjacent Eurasian shelf, on which the structural prolongation of the shallow shelf into deep-water is obviously seen.

Artificial neural systems for interpretation and inversion of seismic data

NASA Astrophysics Data System (ADS)

Calderon-Macias, Carlos

The goal of this work is to investigate the feasibility of using neural network (NN) models for solving geophysical exploration problems. First, a feedforward neural network (FNN) is used to solve inverse problems. The operational characteristics of a FNN are primarily controlled by a set of weights and a nonlinear function that performs a mapping between two sets of data. In a process known as training, the FNN weights are iteratively adjusted to perform the mapping. After training, the computed weights encode important features of the data that enable one pattern to be distinguished from another. Synthetic data computed from an ensemble of earth models and the corresponding models provide the training data. Two training methods are studied: the backpropagation method which is a gradient scheme, and a global optimization method called very fast simulated annealing (VFSA). A trained network is then used to predict models from new data (e.g., data from a new location) in a one-step procedure. The application of this method to the problems of obtaining formation resistivities and layer thicknesses from resistivity sounding data and 1D velocity models from seismic data shows that trained FNNs produce reasonably accurate earth models when observed data are input to the FNNs. In a second application, a FNN is used for automating the NMO correction process of seismic reflection data. The task of the FNN is to map CMP data at control locations along a seismic line into subsurface velocities. The network is trained while the velocity analyses are performed at the control locations. Once trained, the computed weights are used as an operator that acts on the remaining CMP data as a velocity interpolator, resulting in a fast method for NMO correction. The second part of this dissertation describes the application of a Hopfield neural network (HNN) to the problems of deconvolution and multiple attenuation. In these applications, the unknown parameters (reflection coefficients and source wavelet in the first problem and an operator in the second) are mapped as neurons of the HNN. The proposed deconvolution method attempts to reproduce the data with a limited number of events. The multiple attenuation method resembles the predictive deconvolution method. Results of this method are compared with a multiple elimination method based on estimating the source wavelet from the seismic data.

Seismic hazard and risk assessment for large Romanian dams situated in the Moldavian Platform

NASA Astrophysics Data System (ADS)

Moldovan, Iren-Adelina; Popescu, Emilia; Otilia Placinta, Anica; Petruta Constantin, Angela; Toma Danila, Dragos; Borleanu, Felix; Emilian Toader, Victorin; Moldoveanu, Traian

2016-04-01

Besides periodical technical inspections, the monitoring and the surveillance of dams' related structures and infrastructures, there are some more seismic specific requirements towards dams' safety. The most important one is the seismic risk assessment that can be accomplished by rating the dams into seismic risk classes using the theory of Bureau and Ballentine (2002), and Bureau (2003), taking into account the maximum expected peak ground motions at the dams site - values obtained using probabilistic hazard assessment approaches (Moldovan et al., 2008), the structures vulnerability and the downstream risk characteristics (human, economical, historic and cultural heritage, etc) in the areas that might be flooded in the case of a dam failure. Probabilistic seismic hazard (PSH), vulnerability and risk studies for dams situated in the Moldavian Platform, starting from Izvorul Muntelui Dam, down on Bistrita and following on Siret River and theirs affluent will be realized. The most vulnerable dams will be studied in detail and flooding maps will be drawn to find the most exposed downstream localities both for risk assessment studies and warnings. GIS maps that clearly indicate areas that are potentially flooded are enough for these studies, thus giving information on the number of inhabitants and goods that may be destroyed. Geospatial servers included topography is sufficient to achieve them, all other further studies are not necessary for downstream risk assessment. The results will consist of local and regional seismic information, dams specific characteristics and locations, seismic hazard maps and risk classes, for all dams sites (for more than 30 dams), inundation maps (for the most vulnerable dams from the region) and possible affected localities. The studies realized in this paper have as final goal to provide the local emergency services with warnings of a potential dam failure and ensuing flood as a result of an large earthquake occurrence, allowing further public training for evacuation. The work is supported from PNII/PCCA 2013 Project DARING 69/2014, financed by UEFISCDI, Romania. Bureau GJ (2003) "Dams and appurtenant facilities" Earthquake Engineering Handbook, CRS Press, WF Chen, and C Scawthorn (eds.), Boca Raton, pp. 26.1-26.47. Bureau GJ and Ballentine GD (2002) "A comprehensive seismic vulnerability and loss assessment of the State of Carolina using HAZUS. Part IV: Dam inventory and vulnerability assessment methodology", 7th National Conference on Earthquake Engineering, July 21-25, Boston, Earthquake Engineering Research Institute, Oakland, CA. Moldovan IA, Popescu E, Constantin A (2008), "Probabilistic seismic hazard assessment in Romania: application for crustal seismic active zones", Romanian Journal of Physics, Vol.53, Nos. 3-4

Electrical conductivity structure of the mantle derived from inversion of geomagnetic observatory data: implications for lateral variations in temperature, composition and water content.

NASA Astrophysics Data System (ADS)

Munch, Federico; Grayver, Alexander; Khan, Amir; Kuvshinov, Alexey

2017-04-01

As most of Earth's interior remains geochemically unsampled, geophysical techniques based on seismology, geodesy, gravimetry, and electromagnetic studies play prominent roles because of their ability to sense structure at depth. Although seismic tomography maps show a variety of structures, separating thermal and compositional contributions from seismic velocities alone still remains a challenging task. Alternatively, as electrical conductivity is sensitive to temperature, chemical composition, oxygen fugacity, water content, and the presence of melt, it can serve for determining chemistry, mineralogy, and physical structure of the deep mantle. In this work we estimate and invert local C-responses (period range 3-100 days) for a number of worldwide geomagnetic observatories to map lateral variations of electrical conductivity in Earth's mantle (400-1600 km depth). The obtained conductivity profiles are interpreted in terms of basalt fraction in a basalt-harzburgite mixture, temperature structure, and water content variations. Interpretation is based on a self-consistent thermodynamic calculation of mineral phase equilibria, electrical conductivity databases, and probabilistic inverse methods.

Probabilistic Seismic Hazard Assessment for Northeast India Region

NASA Astrophysics Data System (ADS)

Das, Ranjit; Sharma, M. L.; Wason, H. R.

2016-08-01

Northeast India bounded by latitudes 20°-30°N and longitudes 87°-98°E is one of the most seismically active areas in the world. This region has experienced several moderate-to-large-sized earthquakes, including the 12 June, 1897 Shillong earthquake ( M w 8.1) and the 15 August, 1950 Assam earthquake ( M w 8.7) which caused loss of human lives and significant damages to buildings highlighting the importance of seismic hazard assessment for the region. Probabilistic seismic hazard assessment of the region has been carried out using a unified moment magnitude catalog prepared by an improved General Orthogonal Regression methodology (Geophys J Int, 190:1091-1096, 2012; Probabilistic seismic hazard assessment of Northeast India region, Ph.D. Thesis, Department of Earthquake Engineering, IIT Roorkee, Roorkee, 2013) with events compiled from various databases (ISC, NEIC,GCMT, IMD) and other available catalogs. The study area has been subdivided into nine seismogenic source zones to account for local variation in tectonics and seismicity characteristics. The seismicity parameters are estimated for each of these source zones, which are input variables into seismic hazard estimation of a region. The seismic hazard analysis of the study region has been performed by dividing the area into grids of size 0.1° × 0.1°. Peak ground acceleration (PGA) and spectral acceleration ( S a) values (for periods of 0.2 and 1 s) have been evaluated at bedrock level corresponding to probability of exceedance (PE) of 50, 20, 10, 2 and 0.5 % in 50 years. These exceedance values correspond to return periods of 100, 225, 475, 2475, and 10,000 years, respectively. The seismic hazard maps have been prepared at the bedrock level, and it is observed that the seismic hazard estimates show a significant local variation in contrast to the uniform hazard value suggested by the Indian standard seismic code [Indian standard, criteria for earthquake-resistant design of structures, fifth edition, Part-I. Bureau of Indian Standards, New Delhi, 2002]. Not only holistic treatment of earthquake catalog and seismogenic zones has been performed, but also higher resolution in spatial distribution could be achieved. The COV maps have been provided with the strong ground-motion maps under various conditions to show the confidence in the results obtained. Results obtained in the present study would be helpful for risk assessment and other disaster mitigation-related studies.

Assessment of pre-crisis and syn-crisis seismic hazard at Campi Flegrei and Mt. Vesuvius volcanoes, Campania, southern Italy

NASA Astrophysics Data System (ADS)

Convertito, Vincenzo; Zollo, Aldo

2011-08-01

In this study, we address the issue of short-term to medium-term probabilistic seismic hazard analysis for two volcanic areas, Campi Flegrei caldera and Mt. Vesuvius in the Campania region of southern Italy. Two different phases of the volcanic activity are considered. The first, which we term the pre-crisis phase, concerns the present quiescent state of the volcanoes that is characterized by low-to-moderate seismicity. The second phase, syn-crisis, concerns the unrest phase that can potentially lead to eruption. For the Campi Flegrei case study, we analyzed the pattern of seismicity during the 1982-1984 ground uplift episode (bradyseism). For Mt. Vesuvius, two different time-evolutionary models for seismicity were adopted, corresponding to different ways in which the volcano might erupt. We performed a site-specific analysis, linked with the hazard map, to investigate the effects of input parameters, in terms of source geometry, mean activity rate, periods of data collection, and return periods, for the syn-crisis phase. The analysis in the present study of the pre-crisis phase allowed a comparison of the results of probabilistic seismic hazard analysis for the two study areas with those provided in the Italian national hazard map. For the Mt. Vesuvius area in particular, the results show that the hazard can be greater than that reported in the national hazard map when information at a local scale is used. For the syn-crisis phase, the main result is that the data recorded during the early months of the unrest phase are substantially representative of the seismic hazard during the whole duration of the crisis.

Probabilistic and Scenario Seismic and Liquefaction Hazard Analysis of the Mississippi Embayment Incorporating Nonlinear Site Effects

NASA Astrophysics Data System (ADS)

Cramer, C. H.; Dhar, M. S.

2017-12-01

The influence of deep sediment deposits of the Mississippi Embayment (ME) on the propagation of seismic waves is poorly understood and remains a major source of uncertainty for site response analysis. Many researchers have studied the effects of these deposits on seismic hazard of the area using available information at the time. In this study, we have used updated and newly available resources for seismic and liquefaction hazard analyses of the ME. We have developed an improved 3D geological model. Additionally, we used surface geological maps from Cupples and Van Arsdale (2013) to prepare liquefaction hazard maps. Both equivalent linear and nonlinear site response codes were used to develop site amplification distributions for use in generating hazard maps. The site amplification distributions are created using the Monte Carlo approach of Cramer et al. (2004, 2006) on a 0.1-degree grid. The 2014 National Seismic Hazard model and attenuation relations (Petersen et al., 2014) are used to prepare seismic hazard maps. Then liquefaction hazard maps are generated using liquefaction probability curves from Holzer (2011) and Cramer et al. (2015). Equivalent linear response (w/ increased precision, restricted nonlinear behavior with depth) shows similar hazard for the ME compared to nonlinear analysis (w/o pore pressure) results. At short periods nonlinear deamplification dominates the hazard, but at long periods resonance amplification dominates. The liquefaction hazard tends to be high in Holocene and late Pleistocene lowland sediments, even with lowered ground water levels, and low in Pleistocene loess of the uplands. Considering pore pressure effects in nonlinear site response analysis at a test site on the lowlands shows amplification of ground motion at short periods. PGA estimates from ME liquefaction and MMI observations are in the 0.25 to 0.4 g range. Our estimated M7.5 PGA hazard within 10 km of the fault can exceed this. Ground motion observations from liquefaction sites in New Zealand and Japan support PGAs below 0.4 g, except at sites within 20 km exhibiting pore-pressure induced acceleration spikes due to cyclic mobility where PGA ranges from 0.5 to 1.5 g. This study is being extended to more detailed seismic and liquefaction hazard studies in five western Tennessee counties under a five year grant from HUD.

Evansville Area Earthquake Hazards Mapping Project (EAEHMP) - Progress Report, 2008

USGS Publications Warehouse

Boyd, Oliver S.; Haase, Jennifer L.; Moore, David W.

2009-01-01

Maps of surficial geology, deterministic and probabilistic seismic hazard, and liquefaction potential index have been prepared by various members of the Evansville Area Earthquake Hazard Mapping Project for seven quadrangles in the Evansville, Indiana, and Henderson, Kentucky, metropolitan areas. The surficial geologic maps feature 23 types of surficial geologic deposits, artificial fill, and undifferentiated bedrock outcrop and include alluvial and lake deposits of the Ohio River valley. Probabilistic and deterministic seismic hazard and liquefaction hazard mapping is made possible by drawing on a wealth of information including surficial geologic maps, water well logs, and in-situ testing profiles using the cone penetration test, standard penetration test, down-hole shear wave velocity tests, and seismic refraction tests. These data were compiled and collected with contributions from the Indiana Geological Survey, Kentucky Geological Survey, Illinois State Geological Survey, United States Geological Survey, and Purdue University. Hazard map products are in progress and are expected to be completed by the end of 2009, with a public roll out in early 2010. Preliminary results suggest that there is a 2 percent probability that peak ground accelerations of about 0.3 g will be exceeded in much of the study area within 50 years, which is similar to the 2002 USGS National Seismic Hazard Maps for a firm rock site value. Accelerations as high as 0.4-0.5 g may be exceeded along the edge of the Ohio River basin. Most of the region outside of the river basin has a low liquefaction potential index (LPI), where the probability that LPI is greater than 5 (that is, there is a high potential for liquefaction) for a M7.7 New Madrid type event is only 20-30 percent. Within the river basin, most of the region has high LPI, where the probability that LPI is greater than 5 for a New Madrid type event is 80-100 percent.

Considering the ranges of uncertainties in the New Probabilistic Seismic Hazard Assessment of Germany - Version 2016

NASA Astrophysics Data System (ADS)

Grunthal, Gottfried; Stromeyer, Dietrich; Bosse, Christian; Cotton, Fabrice; Bindi, Dino

2017-04-01

The seismic load parameters for the upcoming National Annex to the Eurocode 8 result from the reassessment of the seismic hazard supported by the German Institution for Civil Engineering . This 2016 version of hazard assessment for Germany as target area was based on a comprehensive involvement of all accessible uncertainties in models and parameters into the approach and the provision of a rational framework for facilitating the uncertainties in a transparent way. The developed seismic hazard model represents significant improvements; i.e. it is based on updated and extended databases, comprehensive ranges of models, robust methods and a selection of a set of ground motion prediction equations of their latest generation. The output specifications were designed according to the user oriented needs as suggested by two review teams supervising the entire project. In particular, seismic load parameters were calculated for rock conditions with a vS30 of 800 ms-1 for three hazard levels (10%, 5% and 2% probability of occurrence or exceedance within 50 years) in form of, e.g., uniform hazard spectra (UHS) based on 19 sprectral periods in the range of 0.01 - 3s, seismic hazard maps for spectral response accelerations for different spectral periods or for macroseismic intensities. The developed hazard model consists of a logic tree with 4040 end branches and essential innovations employed to capture epistemic uncertainties and aleatory variabilities. The computation scheme enables the sound calculation of the mean and any quantile of required seismic load parameters. Mean, median and 84th percentiles of load parameters were provided together with the full calculation model to clearly illustrate the uncertainties of such a probabilistic assessment for a region of a low-to-moderate level of seismicity. The regional variations of these uncertainties (e.g. ratios between the mean and median hazard estimations) were analyzed and discussed.

Earthquake Intensity and Strong Motion Analysis Within SEISCOMP3

NASA Astrophysics Data System (ADS)

Becker, J.; Weber, B.; Ghasemi, H.; Cummins, P. R.; Murjaya, J.; Rudyanto, A.; Rößler, D.

2017-12-01

Measuring and predicting ground motion parameters including seismic intensities for earthquakes is crucial and subject to recent research in engineering seismology.gempa has developed the new SIGMA module for Seismic Intensity and Ground Motion Analysis. The module is based on the SeisComP3 framework extending it in the field of seismic hazard assessment and engineering seismology. SIGMA may work with or independently of SeisComP3 by supporting FDSN Web services for importing earthquake or station information and waveforms. It provides a user-friendly and modern graphical interface for semi-automatic and interactive strong motion data processing. SIGMA provides intensity and (P)SA maps based on GMPE's or recorded data. It calculates the most common strong motion parameters, e.g. PGA/PGV/PGD, Arias intensity and duration, Tp, Tm, CAV, SED and Fourier-, power- and response spectra. GMPE's are configurable. Supporting C++ and Python plug-ins, standard and customized GMPE's including the OpenQuake Hazard Library can be easily integrated and compared. Originally tailored to specifications by Geoscience Australia and BMKG (Indonesia) SIGMA has become a popular tool among SeisComP3 users concerned with seismic hazard and strong motion seismology.

Seismic noise attenuation using an online subspace tracking algorithm

NASA Astrophysics Data System (ADS)

Zhou, Yatong; Li, Shuhua; Zhang, Dong; Chen, Yangkang

2018-02-01

We propose a new low-rank based noise attenuation method using an efficient algorithm for tracking subspaces from highly corrupted seismic observations. The subspace tracking algorithm requires only basic linear algebraic manipulations. The algorithm is derived by analysing incremental gradient descent on the Grassmannian manifold of subspaces. When the multidimensional seismic data are mapped to a low-rank space, the subspace tracking algorithm can be directly applied to the input low-rank matrix to estimate the useful signals. Since the subspace tracking algorithm is an online algorithm, it is more robust to random noise than traditional truncated singular value decomposition (TSVD) based subspace tracking algorithm. Compared with the state-of-the-art algorithms, the proposed denoising method can obtain better performance. More specifically, the proposed method outperforms the TSVD-based singular spectrum analysis method in causing less residual noise and also in saving half of the computational cost. Several synthetic and field data examples with different levels of complexities demonstrate the effectiveness and robustness of the presented algorithm in rejecting different types of noise including random noise, spiky noise, blending noise, and coherent noise.

Seismic Oceanography's Failure to Flourish: A Possible Solution

NASA Astrophysics Data System (ADS)

Ruddick, B. R.

2018-01-01

A recent paper in Journal of Geophysical Research: Oceans used multichannel seismic observations to map estimates of internal wave mixing in the Gulf of Mexico, finding greatly enhanced mixing over the slope region. These results suggest that the ocean margins may supply the mixing required to close the global thermohaline circulation, and the techniques demonstrated here might be used to map mixing over much of the world's continental shelves. The use of multichannel seismics to image ocean phenomena is nearly 15 years old, and despite the initial promise, the techniques have not become as broadly used as initially expected. We discuss possible reasons for this, and suggest an alternative approach that might gain broader success.

Assessing Seismic Hazards - Algorithms, Maps, and Emergency Scenarios

NASA Astrophysics Data System (ADS)

Ferriz, H.

2007-05-01

Public officials in charge of building codes, land use planning, and emergency response need sound estimates of seismic hazards. Sources may be well defined (e.g., active faults that have a surface trace) or diffuse (e.g., a subduction zone or a blind-thrust belt), but in both cases one can use a deterministic or worst-case scenario approach. For each scenario, a design earthquake is selected based on historic data or the known length of Holocene ruptures (as determined by geologic mapping). Horizontal ground accelerations (HGAs) can then be estimated at different distances from the earthquake epicenter using published attenuation relations (e.g., Seismological Res. Letters, v. 68, 1997) and estimates of the elastic properties of the substrate materials. No good algorithms are available to take into account reflection of elastic waves across other fault planes (e.g., a common effect in California, where there are many strands of the San Andreas fault), or amplification of waves in water-saturated alluvial and lacustrine basins (e.g., the Mexico City basin), but empirical relations can be developed by correlating historic damage patterns with predicted HGAs. The ultimate result is a map of HGAs. With this map, and with additional data on depth to groundwater and geotechnical properties of local soils, a liquefaction susceptibility map can be prepared, using published algorithms (e.g., J. of Geotech. Geoenv. Eng., v. 127, p. 817-833, 2001; Eng. Geology Practice in N. California, p. 579-594, 2001). Finally, the HGA estimates, digital elevation models, geologic structural data, and geotechnical properties of local geologic units can be used to prepare a slope failure susceptibility map (e.g., Eng. Geology Practice in N. California, p. 77-94, 2001). Seismic hazard maps are used by: (1) Building officials to determine areas of the city where special construction codes have to be implemented, and where existing buildings may need to be retrofitted. (2) Planning officials to evaluate plans for new growth (though in most cities land use patterns are historically established). (3) Emergency response officials to plan emergency operations. (4) Insurance commissioners to estimate losses and insurance claims (e.g., with FEMA's software HAZUS).

Seismic velocity deviation log: An effective method for evaluating spatial distribution of reservoir pore types

NASA Astrophysics Data System (ADS)

Shirmohamadi, Mohamad; Kadkhodaie, Ali; Rahimpour-Bonab, Hossain; Faraji, Mohammad Ali

2017-04-01

Velocity deviation log (VDL) is a synthetic log used to determine pore types in reservoir rocks based on a combination of the sonic log with neutron-density logs. The current study proposes a two step approach to create a map of porosity and pore types by integrating the results of petrographic studies, well logs and seismic data. In the first step, velocity deviation log was created from the combination of the sonic log with the neutron-density log. The results allowed identifying negative, zero and positive deviations based on the created synthetic velocity log. Negative velocity deviations (below - 500 m/s) indicate connected or interconnected pores and fractures, while positive deviations (above + 500 m/s) are related to isolated pores. Zero deviations in the range of [- 500 m/s, + 500 m/s] are in good agreement with intercrystalline and microporosities. The results of petrographic studies were used to validate the main pore type derived from velocity deviation log. In the next step, velocity deviation log was estimated from seismic data by using a probabilistic neural network model. For this purpose, the inverted acoustic impedance along with the amplitude based seismic attributes were formulated to VDL. The methodology is illustrated by performing a case study from the Hendijan oilfield, northwestern Persian Gulf. The results of this study show that integration of petrographic, well logs and seismic attributes is an instrumental way for understanding the spatial distribution of main reservoir pore types.

Autonomous microexplosives subsurface tracing system final report.

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

Engler, Bruce Phillip; Nogan, John; Melof, Brian Matthew

The objective of the autonomous micro-explosive subsurface tracing system is to image the location and geometry of hydraulically induced fractures in subsurface petroleum reservoirs. This system is based on the insertion of a swarm of autonomous micro-explosive packages during the fracturing process, with subsequent triggering of the energetic material to create an array of micro-seismic sources that can be detected and analyzed using existing seismic receiver arrays and analysis software. The project included investigations of energetic mixtures, triggering systems, package size and shape, and seismic output. Given the current absence of any technology capable of such high resolution mapping ofmore » subsurface structures, this technology has the potential for major impact on petroleum industry, which spends approximately $1 billion dollar per year on hydraulic fracturing operations in the United States alone.« less

New Intensity Attenuation in Georgia

NASA Astrophysics Data System (ADS)

Tsereteli, N. S.; Varazanashvili, O.; Tibaldi, A.; Bonali, F.; Gogoladze, Z.; Kvavadze, N.; Kvedelidze, I.

2016-12-01

In seismic-prone zones, increase of urbanization and infrastructures in turn produces increase of seismic risk that is mainly related to: the level of seismic hazard itself, the seismic resistance of dwelling houses, and many other factors. The relevant objectives of the present work is to improve the regional seismic hazard maps of Georgia, by implementing state-of-the art probabilistic seismic hazard assessment techniques and outputs from recent national and international collaborations. Seismic zoning is the identification of zones of similar levels of earthquake hazard. With reference to seismic zoning by ground motion assessment, the shaking intensity essentially depends on i) regional seismicity, ii) attenuation of ground motion with distance, iii) local site effects on ground motion. In the last decade, seismic hazard assessment is presented in terms of Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), or other recorded parameters. But there are very limited strong motion dataset in Georgia. Furthermore, vulnerability of buildings still is estimated for intensity, and there are no information about correlation between the distribution of ground motion recorded parameters and damage. So, macroseimic Intensity is still a very important parameter for strong ground motion evaluation. In the present work, we calibrated intensity prediction equations (IPE) for the Georgian dataset based on about 78 reviewed earthquakes. Metadata for Intensity (MSK 64 scale) were constrained and predictionequations for various types of distance (epicentral and hypocentral distance, Joyner-Boore distance, closest distance to the fault rupture plane) were calibrated. Relations between intensity and PGA values were derived. For this we used hybrid-empirical ground motion equation derived for Georgia and run scenario earthquakes for events with macroseismic data.

Hydrocarbon Reservoir Prediction Using Bi-Gaussian S Transform Based Time-Frequency Analysis Approach

NASA Astrophysics Data System (ADS)

Cheng, Z.; Chen, Y.; Liu, Y.; Liu, W.; Zhang, G.

2015-12-01

Among those hydrocarbon reservoir detection techniques, the time-frequency analysis based approach is one of the most widely used approaches because of its straightforward indication of low-frequency anomalies from the time-frequency maps, that is to say, the low-frequency bright spots usually indicate the potential hydrocarbon reservoirs. The time-frequency analysis based approach is easy to implement, and more importantly, is usually of high fidelity in reservoir prediction, compared with the state-of-the-art approaches, and thus is of great interest to petroleum geologists, geophysicists, and reservoir engineers. The S transform has been frequently used in obtaining the time-frequency maps because of its better performance in controlling the compromise between the time and frequency resolutions than the alternatives, such as the short-time Fourier transform, Gabor transform, and continuous wavelet transform. The window function used in the majority of previous S transform applications is the symmetric Gaussian window. However, one problem with the symmetric Gaussian window is the degradation of time resolution in the time-frequency map due to the long front taper. In our study, a bi-Gaussian S transform that substitutes the symmetric Gaussian window with an asymmetry bi-Gaussian window is proposed to analyze the multi-channel seismic data in order to predict hydrocarbon reservoirs. The bi-Gaussian window introduces asymmetry in the resultant time-frequency spectrum, with time resolution better in the front direction, as compared with the back direction. It is the first time that the bi-Gaussian S transform is used for analyzing multi-channel post-stack seismic data in order to predict hydrocarbon reservoirs since its invention in 2003. The superiority of the bi-Gaussian S transform over traditional S transform is tested on a real land seismic data example. The performance shows that the enhanced temporal resolution can help us depict more clearly the edge of the hydrocarbon reservoir, especially when the thickness of the reservoir is small (such as the thin beds).

Hawaiian Volcano Observatory seismic data, January to March 2009

USGS Publications Warehouse

Nakata, Jennifer S.; Okubo, Paul G.

2010-01-01

Figures 11–14 are maps showing computer-located hypocenters. The maps were generated using the Generic Mapping Tools (GMT), found at http://gmt.soest.hawaii.edu/ (last accessed 01/22/2010), in place of traditional QPLOT maps.

Geodetic survey as a means of improving fast MASW (Multichannel Analysis Of Surface Waves) profiling in difficult terrain/land conditions

NASA Astrophysics Data System (ADS)

Matuła, Rafał; Lewińska, Paulina

2018-01-01

This paper revolves around newly designed and constructed system that can make 2D seismic measurement in natural, subsoil conditions and role of land survey in obtaining accurate results and linking them to 3D surface maps. A new type of land streamer, designed for shallow subsurface exploration is described in this paper. In land seismic data acquisition methods a vehicle tows a line of seismic cable, lying on construction called streamer. The measurements of points and shots are taken while the line is stationary, arbitrary placed on seismic profile. Exposed land streamer consists of 24 innovatory gimballed 10 Hz geophones. It eliminates the need for hand `planting' of geophones, reducing time and costs. With the use of current survey techniques all data obtained with this instrument are being transferred in to 2D and 3D maps. This process is becoming more automatic.

Model uncertainties of the 2002 update of California seismic hazard maps

USGS Publications Warehouse

Cao, T.; Petersen, M.D.; Frankel, A.D.

2005-01-01

In this article we present and explore the source and ground-motion model uncertainty and parametric sensitivity for the 2002 update of the California probabilistic seismic hazard maps. Our approach is to implement a Monte Carlo simulation that allows for independent sampling from fault to fault in each simulation. The source-distance dependent characteristics of the uncertainty maps of seismic hazard are explained by the fundamental uncertainty patterns from four basic test cases, in which the uncertainties from one-fault and two-fault systems are studied in detail. The California coefficient of variation (COV, ratio of the standard deviation to the mean) map for peak ground acceleration (10% of exceedance in 50 years) shows lower values (0.1-0.15) along the San Andreas fault system and other class A faults than along class B faults (0.2-0.3). High COV values (0.4-0.6) are found around the Garlock, Anacapa-Dume, and Palos Verdes faults in southern California and around the Maacama fault and Cascadia subduction zone in northern California.

Seismicity of the Earth 1900-2007

USGS Publications Warehouse

Tarr, Arthur C.; Villaseñor, Antonio; Furlong, Kevin P.; Rhea, Susan; Benz, Harley M.

2010-01-01

This map illustrates more than one century of global seismicity in the context of global plate tectonics and the Earth's physiography. Primarily designed for use by earth scientists and engineers interested in earthquake hazards of the 20th and early 21st centuries, this map provides a comprehensive overview of strong earthquakes since 1900. The map clearly identifies the location of the 'great' earthquakes (M8.0 and larger) and the rupture area, if known, of the M8.3 or larger earthquakes. The earthquake symbols are scaled proportional to the moment magnitude and therefore to the area of faulting, thus providing a better understanding of the relative sizes and distribution of earthquakes in the magnitude range 5.5 to 9.5. Plotting the known rupture area of the largest earthquakes also provides a better appreciation of the extent of some of the most famous and damaging earthquakes in modern history. All earthquakes shown on the map were carefully relocated using a standard earth reference model and standardized location procedures, thereby eliminating gross errors and biases in locations of historically important earthquakes that are often found in numerous seismicity catalogs.

Seismic attribute analysis for reservoir and fluid prediction, Malay Basin

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

Mansor, M.N.; Rudolph, K.W.; Richards, F.B.

1994-07-01

The Malay Basin is characterized by excellent seismic data quality, but complex clastic reservoir architecture. With these characteristics, seismic attribute analysis is a very important tool in exploration and development geoscience and is routinely used for mapping fluids and reservoir, recognizing and risking traps, assessment, depth conversion, well placement, and field development planning. Attribute analysis can be successfully applied to both 2-D and 3-D data as demonstrated by comparisons of 2-D and 3-D amplitude maps of the same area. There are many different methods of extracting amplitude information from seismic data, including amplitude mapping, horizon slice, summed horizon slice, isochronmore » slice, and horizon slice from AVO (amplitude versus offset) cube. Within the Malay Basin, horizon/isochron slice techniques have several advantages over simply extracting amplitudes from a picked horizon: they are much faster, permit examination of the amplitude structure of the entire cube, yield better results for weak/variable signatures, and aid summation of amplitudes. Summation in itself often yields improved results because it incorporates the signature from the entire reservoir interval, reducing any effects due to noise, mispicking, or waveform variations. Dip and azimuth attributes have been widely applied by industry for fault identification. In addition, these attributes can also be used to map signature variations associated with hydrocarbon contacts or stratigraphic changes, and this must be considered when using these attributes for structural interpretation.« less

Structure of pseudotachylyte vein systems as a key to co-seismic rupture dynamics: the case of Gavilgarh-Tan Shear Zone, central India

NASA Astrophysics Data System (ADS)

Chattopadhyay, A.; Bhattacharjee, D.; Mukherjee, S.

2014-04-01

The secondary fractures associated with a major pseudotachylyte-bearing fault vein in the sheared aplitic granitoid of the Proterozoic Gavilgarh-Tan Shear Zone in central India are mapped at the outcrop scale. The fracture maps help to identify at least three different types of co-seismic ruptures, e.g., X-X', T1 and T2, which characterize sinistral-sense shearing of rocks, confined between two sinistral strike-slip faults slipping at seismic rate. From the asymmetric distribution of tensile fractures around the sinistral-sense fault vein, the direction of seismic rupture propagation is predicted to have occurred from west-southwest to east-northeast, during an ancient (Ordovician?) earthquake. Calculations of approximate co-seismic displacement on the faults and seismic moment ( M 0) of the earthquake are attempted, following the methods proposed by earlier workers. These estimates broadly agree to the findings from other studied fault zones (e.g., Gole Larghe Fault zone, Italian Alps). This study supports the proposition by some researchers that important seismological information can be extracted from tectonic pseudotachylytes of all ages, provided they are not reworked by subsequent tectonic activity.

Deterministic seismic hazard macrozonation of India

NASA Astrophysics Data System (ADS)

Kolathayar, Sreevalsa; Sitharam, T. G.; Vipin, K. S.

2012-10-01

Earthquakes are known to have occurred in Indian subcontinent from ancient times. This paper presents the results of seismic hazard analysis of India (6°-38°N and 68°-98°E) based on the deterministic approach using latest seismicity data (up to 2010). The hazard analysis was done using two different source models (linear sources and point sources) and 12 well recognized attenuation relations considering varied tectonic provinces in the region. The earthquake data obtained from different sources were homogenized and declustered and a total of 27,146 earthquakes of moment magnitude 4 and above were listed in the study area. The sesismotectonic map of the study area was prepared by considering the faults, lineaments and the shear zones which are associated with earthquakes of magnitude 4 and above. A new program was developed in MATLAB for smoothing of the point sources. For assessing the seismic hazard, the study area was divided into small grids of size 0.1° × 0.1° (approximately 10 × 10 km), and the hazard parameters were calculated at the center of each of these grid cells by considering all the seismic sources within a radius of 300 to 400 km. Rock level peak horizontal acceleration (PHA) and spectral accelerations for periods 0.1 and 1 s have been calculated for all the grid points with a deterministic approach using a code written in MATLAB. Epistemic uncertainty in hazard definition has been tackled within a logic-tree framework considering two types of sources and three attenuation models for each grid point. The hazard evaluation without logic tree approach also has been done for comparison of the results. The contour maps showing the spatial variation of hazard values are presented in the paper.

Enhanced Rayleigh waves tomography of Mexico using ambient noise cross-correlations (C1) and correlations of coda of correlations (C3)

NASA Astrophysics Data System (ADS)

Spica, Z. J.; Perton, M.; Calo, M.; Cordoba-Montiel, F.; Legrand, D.; Iglesias, A.

2015-12-01

Standard application of the seismic ambient noise tomography considers the existence of synchronous records at stations for green's functions retrieval. More recent theoretical and experimental observations showed the possibility to apply correlation of coda of noise correlation (C3) to obtain green's functions between stations of asynchronous seismic networks making possible to dramatically increase databases for imagining the Earth's interior. However, this possibility has not been fully exploited yet, and right now the data C3 are not included into tomographic inversions to refine seismic structures. Here we show for the first time how to incorporate the data of C1 and C3 to calculate dispersion maps of Rayleigh waves in the range period of 10-120s, and how the merging of these datasets improves the resolution of the structures imaged. Tomographic images are obtained for an area covering Mexico, the Gulf of Mexico and the southern U.S. We show dispersion maps calculated using both data of C1 and the complete dataset (C1+C3). The latter provide new details of the seismic structure of the region allowing a better understanding of their role on the geodynamics of the study area. The resolving power obtained in our study is several times higher than in previous studies based on ambient noise. This demonstrates the new possibilities for imaging the Earth's crust and upper mantle using this enlarged database.

An earthquake rate forecast for Europe based on smoothed seismicity and smoothed fault contribution

NASA Astrophysics Data System (ADS)

Hiemer, Stefan; Woessner, Jochen; Basili, Roberto; Wiemer, Stefan

2013-04-01

The main objective of project SHARE (Seismic Hazard Harmonization in Europe) is to develop a community-based seismic hazard model for the Euro-Mediterranean region. The logic tree of earthquake rupture forecasts comprises several methodologies including smoothed seismicity approaches. Smoothed seismicity thus represents an alternative concept to express the degree of spatial stationarity of seismicity and provides results that are more objective, reproducible, and testable. Nonetheless, the smoothed-seismicity approach suffers from the common drawback of being generally based on earthquake catalogs alone, i.e. the wealth of knowledge from geology is completely ignored. We present a model that applies the kernel-smoothing method to both past earthquake locations and slip rates on mapped crustal faults and subductions. The result is mainly driven by the data, being independent of subjective delineation of seismic source zones. The core parts of our model are two distinct location probability densities: The first is computed by smoothing past seismicity (using variable kernel smoothing to account for varying data density). The second is obtained by smoothing fault moment rate contributions. The fault moment rates are calculated by summing the moment rate of each fault patch on a fully parameterized and discretized fault as available from the SHARE fault database. We assume that the regional frequency-magnitude distribution of the entire study area is well known and estimate the a- and b-value of a truncated Gutenberg-Richter magnitude distribution based on a maximum likelihood approach that considers the spatial and temporal completeness history of the seismic catalog. The two location probability densities are linearly weighted as a function of magnitude assuming that (1) the occurrence of past seismicity is a good proxy to forecast occurrence of future seismicity and (2) future large-magnitude events occur more likely in the vicinity of known faults. Consequently, the underlying location density of our model depends on the magnitude. We scale the density with the estimated a-value in order to construct a forecast that specifies the earthquake rate in each longitude-latitude-magnitude bin. The model is intended to be one branch of SHARE's logic tree of rupture forecasts and provides rates of events in the magnitude range of 5 <= m <= 8.5 for the entire region of interest and is suitable for comparison with other long-term models in the framework of the Collaboratory for the Study of Earthquake Predictability (CSEP).

Earthquakes of the Central United States, 1795-2002

USGS Publications Warehouse

Wheeler, Russell L.

2003-01-01

This report describes construction of a list of Central U.S. earthquakes to be shown on a large-format map that is targeted for a non-technical audience. The map shows the locations and sizes of historical earthquakes of magnitude 3.0 or larger over the most seismically active part of the central U.S., including the New Madrid seismic zone. The map shows more than one-half million square kilometers and parts or all of ten States. No existing earthquake catalog had provided current, uniform coverage down to magnitude 3.0, so one had to be made. Consultation with State geological surveys insured compatibility with earthquake lists maintained by them, thereby allowing the surveys and the map to present consistent information to the public.

Constraining the crustal root geometry beneath the Rif Cordillera (North Morocco)

NASA Astrophysics Data System (ADS)

Diaz, Jordi; Gil, Alba; Carbonell, Ramon; Gallart, Josep; Harnafi, Mimoun

2016-04-01

The analyses of wide-angle reflections of controlled source experiments and receiver functions calculated from teleseismic events provide consistent constraints of an over-thickened crust beneath the Rif Cordillera (North Morocco). Regarding active source data, we investigate now offline arrivals of Moho-reflected phases recorded in RIFSIS project to get new estimations of 3D crustal thickness variations beneath North Morocco. Additional constrains on the onshore-offshore transition are derived from onland recording of marine airgun shots from the coeval Gassis-Topomed profiles. A regional crustal thickness map is computed from all these results. In parallel, we use natural seismicity data collected throughout TopoIberia and PICASSO experiments, and from a new RIFSIS deployment, to obtain teleseismic receiver functions and explore the crustal thickness variations with a H-κ grid-search approach. The use of a larger dataset including new stations covering the complex areas beneath the Rif Cordillera allow us to improve the resolution of previous contributions, revealing abrupt crustal changes beneath the region. A gridded surface is built up by interpolating the Moho depths inferred for each seismic station, then compared with the map from controlled source experiments. A remarkably consistent image is observed in both maps, derived from completely independent data and methods. Both approaches document a large modest root, exceeding 50 km depth in the central part of the Rif, in contrast with the rather small topographic elevations. This large crustal thickness, consistent with the available Bouguer anomaly data, favor models proposing that the high velocity slab imaged by seismic tomography beneath the Alboran Sea is still attached to the lithosphere beneath the Rif, hence pulling down the lithosphere and thickening the crust. The thickened area corresponds to a quiet seismic zone located between the western Morocco arcuate seismic zone, the deep seismicity area beneath western Alboran Sea and the superficial seismicity in Alhoceima area. Therefore, the presence of a crustal root seems to play also a major role in the seismicity distribution in northern Morocco.

A Moore's cellular automaton model to get probabilistic seismic hazard maps for different magnitude releases: A case study for Greece

NASA Astrophysics Data System (ADS)

Jiménez, A.; Posadas, A. M.

2006-09-01

Cellular automata are simple mathematical idealizations of natural systems and they supply useful models for many investigations in natural science. Examples include sandpile models, forest fire models, and slider block models used in seismology. In the present paper, they have been used for establishing temporal relations between the energy releases of the seismic events that occurred in neighboring parts of the crust. The catalogue is divided into time intervals, and the region is divided into cells which are declared active or inactive by means of a threshold energy release criterion. Thus, a pattern of active and inactive cells which evolves over time is determined. A stochastic cellular automaton is constructed starting with these patterns, in order to simulate their spatio-temporal evolution, by supposing a Moore's neighborhood interaction between the cells. The best model is chosen by maximizing the mutual information between the past and the future states. Finally, a Probabilistic Seismic Hazard Map is given for the different energy releases considered. The method has been applied to the Greece catalogue from 1900 to 1999. The Probabilistic Seismic Hazard Maps for energies corresponding to m = 4 and m = 5 are close to the real seismicity after the data in that area, and they correspond to a background seismicity in the whole area. This background seismicity seems to cover the whole area in periods of around 25-50 years. The optimum cell size is in agreement with other studies; for m > 6 the optimum area increases according to the threshold of clear spatial resolution, and the active cells are not so clustered. The results are coherent with other hazard studies in the zone and with the seismicity recorded after the data set, as well as provide an interaction model which points out the large scale nature of the earthquake occurrence.

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.

New insights into the earliest Quaternary environments in the Central North Sea from 3D seismic

NASA Astrophysics Data System (ADS)

Lamb, Rachel; Huuse, Mads; Stewart, Margaret; Brocklehurst, Simon H.

2014-05-01

In the past the transition between an unconformable surface in the south to a conformable horizon towards the north has made identification and mapping the base-Quaternary in the central North Sea difficult (Sejrup et al 1991; Gatliff et al 1994). However recent integration of biostratigraphy, pollen analysis, paleomagnetism and amino acid analysis in the Dutch and Danish sectors (Rasmussen et al 2005; Kuhlmann et al 2006) has allowed greater confidence in the correlation to the region 3D seismic datasets and thus has allowed the base-Quaternary to be mapped across the entire basin. The base-Quaternary has been mapped using the PGS MegaSurvey dataset from wells in the Danish Sector along the initially unconformable horizon and down the delta front into the more conformable basin giving a high degree of confidence in the horizon pick. The revised base-Quaternary surface reaches a depth of 1248 ms TWT with an elongate basin shape which is significantly deeper than the traditionally mapped surface. Using RMS amplitudes and other seismic attributes the revised base-Quaternary has been investigated along the horizon and in time slice to interpret the environments of the earliest Quaternary prior to the onset of glaciation. Combined with analysis of aligned elongate furrows over 10 km long, 100 m wide and 100 m deep suggest a deep marine environment in an almost enclosed basin with persistent strong NW-SE bottom currents in the deepest parts. Pockmarks were formed by the escape of shallow gas on the sides of a small delta in the eastern part of the basin. The progradation of large deltas from both the north and south into the basin make up the majority of the deposition of sediment into the basin. Key Words: base-Quaternary; seismic interpretation; paleoenvironments References: Gatliff, R.W, Richards, P.C, Smith, K, Graham, C.C, McCormac, M, Smith, N.J.P, Long, D, Cameron, T.D.J, Evans, D, Stevenson, A.G, Bulat, J, Ritchie, J.D, (1994) 'United Kingdom offshore regional report: the geology of the central North Sea.' London: HMSO for the British Geological Survey Kuhlmann, G., Langereis C.G., Munsterman, D., van Leeuwen, R.-J., Verreussel, R., Meulenkamp, J.E., Wong, Th.E., 2006 'Intergrated chronostratigraphy of the Pliocene-Pliestocene interval and its relation to the regional stratigraphical stages in the Southern North Sea region' Netherlands Journal of Geosciences 85(1), 29-45 Rasmussen, E.A., Vejb?k O.V., Bidstrup, T., Piasecki, S., Dybkj?r, K., 2005 'Late Cenozoic depositional history of the Danish North Sea Basin: implications for the petroleum systems in the Kraka, Halfdan, Siri and Nini fields', Petroleum Geology Conference series 6, 1347-1358 Sejrup, H.P., Aareseth, I., Haflidason, H., 1991 'The Quaternary succession in the northern North Sea' Marine Geology 101 103-111

Three-dimensional fluid mapping and earthquake probabilities for induced seismicity sequences

NASA Astrophysics Data System (ADS)

Bachmann, C. E.; Wiemer, S.; Woessner, J.

2010-12-01

To stimulate the reservoir for a proposed enhanced geothermal system (EGS) project in the City of Basel, approximately 11500 m3 of water were injected at high pressures into a 5 km deep well between December 2nd and 8th, 2006. A six-sensor borehole array, installed by Geothermal Explorers Limited at depths between 50 and 2700 meters around the well to monitor the induced seismicity, recorded some 15000 events during the injection phase, more than 3500 of them locatable. The induced seismicity covers an area of about two square kilometers between 3 and 5 km depth. Water injection was stopped after a widely felt ML 3.4 event that occurred on December 8th. Here, we map in space and time statistical parameters that describe the seismicity, such as the magnitude of completeness, Mc the b- and a- value of the frequency-magnitude distribution and the local probability of large events. We find that the completeness level varies from Mc= 0.5 to Mc=0.8, where the lowest completeness is observed for the shallowest seismicity. Higher b-values are located close to the initiation point of the injection at the casing shoe. With time, and with the gradual expansion of the seismicity, the b-values decrease near the edges of the seismicity cloud. The b-values range from 1.0 to above 2.0; large events occur preferentially in regions of previously low b-value. The local earthquake probabilities for a larger (M3+) event determined from the local a- and b-value show a clear correlation with the occurrence of events in this magnitude range, suggesting that by mapping the local a- and b-values, large magnitude events could be forecasted with greater accuracy than possible when using bulk values only. There are several different hypotheses how to explain induced seismicity, including increasing pore pressure, temperature decrease, volume changes and chemical alterations of fraction surfaces. All of these are linked to the fluid migration within the rock. Previously, high b-values have been shown to correlate with the presence of magma and fluids in volcanic areas and subduction zones. Additionally, b-values have been shown to be inversely proportional to the applied shear stress. Our results indicate that often-stated assumption that induced sequences are showing a high b-value is too simplistic. Rather, anomalously high values close to the casing shoe are embedded in average values further away. These zones of high b-values experience the highest changes in pore pressure, we therefore suggest a correlation between b-values and pore pressure. Towards the rim of seismicity, we find lower b-values, close to typical tectonic values, indicating that the seismicity may not primarily be caused by fluid overpressure. Based on our results, we suggest that b-values are linked to fluid migration; zones with high b-values indicate preferential fluid flow directions, zones with low b-values suggest seismicity that is not directly linked to water flow.

VAFB-20180329-PH_CNW01_0019

NASA Image and Video Library

2018-03-29

In the Astrotech facility at Vandenberg Air Force Base in California, the heatshield is lifted for placement on NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

VAFB-20180329-PH_CNW01_0031

NASA Image and Video Library

2018-03-29

In the Astrotech facility at Vandenberg Air Force Base in California, the heatshield is placed on NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Encapsulation

NASA Image and Video Library

2018-04-16

In the Astrotech facility at Vandenberg Air Force Base in California, NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander is encapsulated in its payload fairing. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Encapsulation

NASA Image and Video Library

2018-04-16

In the Astrotech facility at Vandenberg Air Force Base in California, technicians and engineers encapsulate NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander in its payload fairing. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

Encapsulated in its payload fairing, NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander is transported to Space Launch Complex 3 at Vandenberg Air Force Base in California. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

Encapsulated in its payload fairing NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander arrives at Space Launch Complex 3 at Vandenberg Air Force Base in California. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

Encapsulated in its payload fairing NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander is transported to Space Launch Complex 3 at Vandenberg Air Force Base in California. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Lift & Mate

NASA Image and Video Library

2018-04-23

Encapsulated in its payload fairing NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander is prepared for transport to Space Launch Complex 3 at Vandenberg Air Force Base in California. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Battery Installation

NASA Image and Video Library

2018-04-20

In the gantry at Space Launch Complex 3 at Vandenberg Air Force Base in California, a technician prepares batteries for installation in NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

Integrated system for well-to-well correlation with geological knowledge base

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

Saito, K.; Doi, E.; Uchiyama, T.

1987-05-01

A task of well-to-well correlation is an essential part of the reservoir description study. Since the task is involved with diverse data such as logs, dipmeter, seismic, and reservoir engineering, a system with simultaneous access to such data is desirable. A system is developed to aid stratigraphic correlation under a Xerox 1108 workstation, written in INTERLISP-D. The system uses log, dipmeter, seismic, and computer-processed results such as Litho-Analysis and LSA (Log Shape Analyzer). The system first defines zones which are segmentations of log data into consistent layers using Litho-Analysis and LSA results. Each zone is defined as a minimum unitmore » for correlation with slot values of lithology, thickness, log values, and log shape such as bell, cylinder, and funnel. Using a user's input of local geological knowledge such as depositional environment, the system selects marker beds and performs correlation among the wells chosen from the base map. Correlation is performed first with markers and then with sandstones of lesser lateral extent. Structural dip and seismic horizon are guides for seeking a correlatable event. Knowledge of sand body geometry such as ratio of thickness and width is also used to provide a guide on how far a correlation should be made. Correlation results performed by the system are displayed on the screen for the user to examine and modify. The system has been tested with data sets from several depositional settings and has shown to be a useful tool for correlation work. The results are stored as a data base for structural mapping and reservoir engineering study.« less

Submarine landslide: A case study from the southwestern of Taiwan offshore

NASA Astrophysics Data System (ADS)

Hung, Y. H.; Dong, J. J.

2016-12-01

Based on the new multibeam bathymetric data and seismic reflection profiles of the southwestern Taiwan, more and more submarine landslides developed there have been being discovered nowadays. Palm Ridge, located between the boundary of the active and passive margins, is the place where a deformation front passes through. And previous studies suspected that there were old submarine landslides developed here. To learn whether there are old submarine landslides here, a further study is conducted with the collection and analysis of new high-resolution swath-bathymetry and seismic data. Firstly, based on the swath-bathymetry, the topography range of the landslide is mapped and interpreted with the three dimensional model. Then, according to the profile of the mapping, the extending of the sliding surface is predicted. And referred on the properties of soil in adjacent region, the engineering geologic models of the landslide before and after failure are proposed. Thirdly, through a detailed analysis of the seismic data of Taiwan in the past three decades, a magnitude of 7.7 MW is selected as the lower bound of earthquake for the analysis of the trigger of the submarine landslide. And based on the record of earthquakes with 8 MW in the world, some other earthquake magnitudes are also considered in this study. After applying them into STABL 5M, the failure process of the landslide is modeled with its possible deposited ranges being reached. Finally, the sub-bottom and seismic data are used to verify the rationality of the above results. Preliminary result shows that there were at least three landslides occurred in Palm Ridge. The first landslide is largest which covers the approximate range of the study area. The second one is developed in the margin area of the first one, which is resulted by the occurrence of the first one. The third event is caused by the further collapse of the first one due to the loose of its inner structure.

Spatial distribution of soil radon as a tool to recognize active faulting on an active volcano: the example of Mt. Etna (Italy).

PubMed

Neri, Marco; Giammanco, Salvatore; Ferrera, Elisabetta; Patanè, Giuseppe; Zanon, Vittorio

2011-09-01

This study concerns measurements of radon and thoron emissions from soil carried out in 2004 on the eastern flank of Mt. Etna, in a zone characterized by the presence of numerous seismogenic and aseismic faults. The statistical treatment of the geochemical data allowed recognizing anomaly thresholds for both parameters and producing distribution maps that highlighted a significant spatial correlation between soil gas anomalies and tectonic lineaments. The seismic activity occurring in and around the study area during 2004 was analyzed, producing maps of hypocentral depth and released seismic energy. Both radon and thoron anomalies were located in areas affected by relatively deep (5-10 km depth) seismic activity, while less evident correlation was found between soil gas anomalies and the released seismic energy. This study confirms that mapping the distribution of radon and thoron in soil gas can reveal hidden faults buried by recent soil cover or faults that are not clearly visible at the surface. The correlation between soil gas data and earthquakes depth and intensity can give some hints on the source of gas and/or on fault dynamics. Copyright © 2011 Elsevier Ltd. All rights reserved.

Revision of the geological context of the Port-au-Prince metropolitan area, Haiti: implications for slope failures and seismic hazard assessment

NASA Astrophysics Data System (ADS)

Terrier, M.; Bialkowski, A.; Nachbaur, A.; Prépetit, C.; Joseph, Y. F.

2014-09-01

Following the earthquake of 12 January 2010 in the Port-au-Prince area, the Haitian government, in close cooperation with BRGM, the French geological Survey, decided to undertake a seismic microzonation study of the metropolitan area of the capital in order to take more fully into account the seismic risk in the urbanization and planning of the city under reconstruction. As the first step of the microzonation project, a geological study has been carried out. Deposits of Miocene and Pliocene formations in a marine environment have been identified. These deposits are affected by the Enriquillo-Plantain Garden N80° E fault system and N110° E faults. Tectonic observations and morphological analysis indicate Quaternary activity of several faults mapped in the area of Port-au-Prince. These faults have a N110° trend and show a reverse-sinistral strike-slip motion. Moreover, on the basis of these geological results and of new topographical data, a hazard assessment of ground movements has been made. Along with the map of active faults, the hazard map of ground movements is an integral component of the seismic microzonation study.

A continuous map of near-surface S-wave attenuation in New Zealand

NASA Astrophysics Data System (ADS)

Van Houtte, Chris; Ktenidou, Olga-Joan; Larkin, Tam; Holden, Caroline

2018-04-01

Quantifying the near-surface attenuation of seismic waves at a given location can be important for seismic hazard analysis of high-frequency ground motion. This study calculates the site attenuation parameter, κ0, at 41 seismograph locations in New Zealand. Combined with results of a previous study, a total of 46 κ0 values are available across New Zealand. The results compare well with previous t* studies, revealing high attenuation in the volcanic arc and forearc ranges, and low attenuation in the South Island. However, for site-specific seismic hazard analyses, there is a need to calculate κ0 at locations away from a seismograph location. For these situations, it is common to infer κ0 from weak correlations with the shear wave velocity in the top 30 m, VS30, or to adopt an indicative regional value. This study attempts to improve on this practice. Geostatistical models of the station-specific κ0 data are developed, and continuous maps are derived using ordinary kriging. The obtained κ0 maps can provide a median κ0 and its uncertainty for any location in New Zealand, which may be useful for future site-specific seismic hazard analyses.

Fast history matching of time-lapse seismic and production data for high resolution models

NASA Astrophysics Data System (ADS)

Jimenez Arismendi, Eduardo Antonio

Integrated reservoir modeling has become an important part of day-to-day decision analysis in oil and gas management practices. A very attractive and promising technology is the use of time-lapse or 4D seismic as an essential component in subsurface modeling. Today, 4D seismic is enabling oil companies to optimize production and increase recovery through monitoring fluid movements throughout the reservoir. 4D seismic advances are also being driven by an increased need by the petroleum engineering community to become more quantitative and accurate in our ability to monitor reservoir processes. Qualitative interpretations of time-lapse anomalies are being replaced by quantitative inversions of 4D seismic data to produce accurate maps of fluid saturations, pore pressure, temperature, among others. Within all steps involved in this subsurface modeling process, the most demanding one is integrating the geologic model with dynamic field data, including 4Dseismic when available. The validation of the geologic model with observed dynamic data is accomplished through a "history matching" (HM) process typically carried out with well-based measurements. Due to low resolution of production data, the validation process is severely limited in its reservoir areal coverage, compromising the quality of the model and any subsequent predictive exercise. This research will aim to provide a novel history matching approach that can use information from high-resolution seismic data to supplement the areally sparse production data. The proposed approach will utilize streamline-derived sensitivities as means of relating the forward model performance with the prior geologic model. The essential ideas underlying this approach are similar to those used for high-frequency approximations in seismic wave propagation. In both cases, this leads to solutions that are defined along "streamlines" (fluid flow), or "rays" (seismic wave propagation). Synthetic and field data examples will be used extensively to demonstrate the value and contribution of this work. Our results show that the problem of non-uniqueness in this complex history matching problem is greatly reduced when constraints in the form of saturation maps from spatially closely sampled seismic data are included. Further on, our methodology can be used to quickly identify discrepancies between static and dynamic modeling. Reducing this gap will ensure robust and reliable models leading to accurate predictions and ultimately an optimum hydrocarbon extraction.

Seismicity map of the State of Georgia

USGS Publications Warehouse

Stover, C.W.; Reagor, B.G.; Algermissen, S.T.; Long, L.T.

1979-01-01

The earthquake data shown on this map and listed in table 1 are a list of earthquakes that were originally used in preparing the Seismic Risk Studies in the United States (Algermissen, 1969) which have been recompiled and updated through 1977. The data have been reexamined and intensities assigned where none had been assigned before, on the basis of available data. Other intensity values were updated from new and additional data sources that were not available at the time of original compilation. Some epicenters were relocated on the basis of new information. The data shown in table 1 are estimates of the most accurate hypocenter, magnitude, and intensity of each earthquake, on the basis of historical and current information. Known or suspected explosions are listed in table 1 but are not plotted on the seismicity map.The data in table 1 were used to compile the seismicity map. The latitude and longitude were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped together and counted. A triangle represents the epicenter plotted to a tenth of a degree. The number of earthquakes at each location is shown on the map by the number to the right of the triangle. A Roman numeral to the left of a triangle is the maximum Modified Mercalli intensity (Wood and Neumann, 1931) of all earthquakes located at that geographic position. The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. A year shown below a triangle is the latest year for which the maximum intensity was recorded.

Tools for educational access to seismic data

NASA Astrophysics Data System (ADS)

Taber, J. J.; Welti, R.; Bravo, T. K.; Hubenthal, M.; Frechette, K.

2017-12-01

Student engagement can be increased both by providing easy access to real data, and by addressing newsworthy events such as recent large earthquakes. IRIS EPO has a suite of access and visualization tools that can be used for such engagement, including a set of three tools that allow students to explore global seismicity, use seismic data to determine Earth structure, and view and analyze near-real-time ground motion data in the classroom. These tools are linked to online lessons that are designed for use in middle school through introductory undergraduate classes. The IRIS Earthquake Browser allows discovery of key aspects of plate tectonics, earthquake locations (in pseudo 3D) and seismicity rates and patterns. IEB quickly displays up to 20,000 seismic events over up to 30 years, making it one of the most responsive, practical ways to visualize historical seismicity in a browser. Maps are bookmarkable and preserve state, meaning IEB map links can be shared or worked into a lesson plan. The Global Seismogram Plotter automatically creates visually clear seismic record sections from selected large earthquakes that are tablet-friendly and can also to be printed for use in a classroom without computers. The plots are designed to be appropriate for use with no parameters to set, but users can also modify the plots, such as including a recording station near a chosen location. A guided exercise is provided where students use the record section to discover the diameter of Earth's outer core. Students can pick and compare phase arrival times onscreen which is key to performing the exercise. A companion station map shows station locations and further information and is linked to the record section. jAmaSeis displays seismic data in real-time from either a local instrument and/or from remote seismic stations that stream data using standard seismic data protocols, and can be used in the classroom or as a public display. Users can filter data, fit a seismogram to travel time curves, triangulate event epicenters on a globe, estimate event magnitudes, and generate images showing seismograms and corresponding calculations. All three tools access seismic databases curated by IRIS Data Services. In addition, jAmaseis also can access data from non-IRIS sources.

Urban MEMS based seismic network for post-earthquakes rapid disaster assessment

NASA Astrophysics Data System (ADS)

D'Alessandro, Antonino; Luzio, Dario; D'Anna, Giuseppe

2014-05-01

Life losses following disastrous earthquake depends mainly by the building vulnerability, intensity of shaking and timeliness of rescue operations. In recent decades, the increase in population and industrial density has significantly increased the exposure to earthquakes of urban areas. The potential impact of a strong earthquake on a town center can be reduced by timely and correct actions of the emergency management centers. A real time urban seismic network can drastically reduce casualties immediately following a strong earthquake, by timely providing information about the distribution of the ground shaking level. Emergency management centers, with functions in the immediate post-earthquake period, could be use this information to allocate and prioritize resources to minimize loss of human life. However, due to the high charges of the seismological instrumentation, the realization of an urban seismic network, which may allow reducing the rate of fatalities, has not been achieved. Recent technological developments in MEMS (Micro Electro-Mechanical Systems) technology could allow today the realization of a high-density urban seismic network for post-earthquakes rapid disaster assessment, suitable for the earthquake effects mitigation. In the 1990s, MEMS accelerometers revolutionized the automotive-airbag system industry and are today widely used in laptops, games controllers and mobile phones. Due to their great commercial successes, the research into and development of MEMS accelerometers are actively pursued around the world. Nowadays, the sensitivity and dynamics of these sensors are such to allow accurate recording of earthquakes with moderate to strong magnitude. Due to their low cost and small size, the MEMS accelerometers may be employed for the realization of high-density seismic networks. The MEMS accelerometers could be installed inside sensitive places (high vulnerability and exposure), such as schools, hospitals, public buildings and places of worship. The waveforms recorded could be promptly used to determine ground-shaking parameters, like peak ground acceleration/velocity/displacement, Arias and Housner intensity, that could be all used to create, few seconds after a strong earthquakes, shaking maps at urban scale. These shaking maps could allow to quickly identify areas of the town center that have had the greatest earthquake resentment. When a strong seismic event occur, the beginning of the ground motion observed at the site could be used to predict the ensuing ground motion at the same site and so to realize a short term earthquake early warning system. The data acquired after a moderate magnitude earthquake, would provide valuable information for the detail seismic microzonation of the area based on direct earthquake shaking observations rather than from a model-based or indirect methods. In this work, we evaluate the feasibility and effectiveness of such seismic network taking in to account both technological, scientific and economic issues. For this purpose, we have simulated the creation of a MEMS based urban seismic network in a medium size city. For the selected town, taking into account the instrumental specifics, the array geometry and the environmental noise, we investigated the ability of the planned network to detect and measure earthquakes of different magnitude generated from realistic near seismogentic sources.

Maps showing the change in modern sediment thickness on the Inner Continental Shelf offshore of Fire Island, New York, between 1996-97 and 2011

USGS Publications Warehouse

Schwab, William C.; Baldwin, Wayne E.; Denny, Jane F.

2015-01-01

The U.S. Geological Survey mapped approximately 336 square kilometers of the lower shoreface and inner continental shelf offshore of Fire Island, New York, in 1996 and 1997, using high-resolution sidescan-sonar and seismic-reflection systems, and again in 2011, using interferometric sonar and high-resolution chirp seismic-reflection systems. This report presents a comparison of sediment thickness and distribution as mapped during these two investigations. These spatial data support research on the Quaternary evolution of the Fire Island coastal system and provide baseline information for research on coastal processes along southern Long Island.

The influence of maximum magnitude on seismic-hazard estimates in the Central and Eastern United States

USGS Publications Warehouse

Mueller, C.S.

2010-01-01

I analyze the sensitivity of seismic-hazard estimates in the central and eastern United States (CEUS) to maximum magnitude (mmax) by exercising the U.S. Geological Survey (USGS) probabilistic hazard model with several mmax alternatives. Seismicity-based sources control the hazard in most of the CEUS, but data seldom provide an objective basis for estimating mmax. The USGS uses preferred mmax values of moment magnitude 7.0 and 7.5 for the CEUS craton and extended margin, respectively, derived from data in stable continental regions worldwide. Other approaches, for example analysis of local seismicity or judgment about a source's seismogenic potential, often lead to much smaller mmax. Alternative models span the mmax ranges from the 1980s Electric Power Research Institute/Seismicity Owners Group (EPRI/SOG) analysis. Results are presented as haz-ard ratios relative to the USGS national seismic hazard maps. One alternative model specifies mmax equal to moment magnitude 5.0 and 5.5 for the craton and margin, respectively, similar to EPRI/SOG for some sources. For 2% probability of exceedance in 50 years (about 0.0004 annual probability), the strong mmax truncation produces hazard ratios equal to 0.35-0.60 for 0.2-sec spectral acceleration, and 0.15-0.35 for 1.0-sec spectral acceleration. Hazard-controlling earthquakes interact with mmax in complex ways. There is a relatively weak dependence on probability level: hazardratios increase 0-15% for 0.002 annual exceedance probability and decrease 5-25% for 0.00001 annual exceedance probability. Although differences at some sites are tempered when faults are added, mmax clearly accounts for some of the discrepancies that are seen in comparisons between USGS-based and EPRI/SOG-based hazard results.

Shallow gas in Cenozoic sediments of the Southern North Sea

NASA Astrophysics Data System (ADS)

Trampe, Anna F.; Lutz, Rüdiger; Franke, Dieter; Thöle, Hauke; Arfai, Jashar

2013-04-01

Shallow petroleum systems in the southern North Sea are known for several decades but they were not actively explored for a long time. In recent years these unconventional shallow petroleum systems are studied in greater detail and one shallow gas field (A-12) is in production in the Netherlands. Additionally, oil was encountered in Miocene sandstones in the southern Danish North Sea (Lille John well) just north of the Danish-German border. Seismic amplitude anomalies are an indication for hydrocarbons in sediments. Therefore we have mapped the occurrence of seismic amplitude anomalies in the German North Sea based on more than 25.000 km of 2D seismic data and around 4.000 km2 of 3D seismic data. Amplitude anomalies are ubiquitous phenomena in the study area. These anomalies are not only caused by hydrocarbons but also by changing lithologies e.g. peat or fluid migration. Therefore several classes of seismic anomalies, e.g. bright spots, chimneys, blanking areas and velocity pull-down were mapped. Examples for these classes were studied with AVO (amplitude variation with offset) analyses to verify the existence or non-existence of gas in the sediments. Shallow gas can be produced and transported through the dense pipeline grid of the southern and central North Sea or it could be burned offshore close to wind parks in small power plants and the electric energy then transported through the existing power connections of the wind parks. Thus enabling a continuous energy supply during calm wind periods. This study is carried out within the framework of the project "Geoscientific Potential of the German North Sea (GPDN)" in which the Cenozoic sedimentary system was mapped in great detail. A detailed model of delta evolution (Baltic river system) was developed which serves as a structural framework. The studied interval is time equivalent to the Utsira formation which is used offshore Norway for sequestration of CO2. These different possibilities of using or exploiting the underground emphasize the need for detailed knowledge on the underground for sound decisions on the future use of this area.

A Possible Buried Impact Structure Near Bow City, Alberta

NASA Astrophysics Data System (ADS)

Xie, W.; Glombick, P.; Schmitt, D. R.; Bown, T. D.

2012-12-01

In recent years, improved exploration techniques have resulted in the serendipitous discoveries of increasing numbers of extraterrestrial impact structures in sedimentary basins around the world. Following in this tradition, a new potential impact structure centered near 50.4°N, 112.35°N in SE Alberta has been identified. The first indications of this structure appeared in careful systematic mapping of Cretaceous age sediments using public domain well log information that showed overturned and missing components in what regionally is a simple layered stratigraphy. This motivated the examination of legacy 2D seismic profiles over the area that confirmed the stratigraphic anomalies and provided new details that further supported interpretation of a potential impact structure. Further, the existence of unexpected faults through the Cretaceous Bearpaw formation had been noted as early as the 1940's in the limited outcrop available in coulees, and these as well as other complex fault structures along the Bow River outcrops were confirmed in recent field visits to the site. The 2D seismic data displays a number of listric and rose-petal faulting consistent with late stage collapse of the impact crater. Further, a seismically transparent central uplift peak is visible. Based on the results, the structure is recognized as a complex crater with a diameter of approximately 8 kilometers and, today, bottoming at a depth of 900 meters from the current surface. Currently, the age of the feature is grossly estimated to be less than 70 my on the basis of underlying undisturbed seismic reflectors. The structure may be somewhat unique in that weak coals surrounding the feature are clearly thickened indicating outward lateral sliding along shear planes through weaker layers. Work in progress includes acquisition of a high resolution seismic profile and detailed mapping of the magnetic and gravity potential fields. More detailed mapping will include searches for shock metamorphism and melt although it is not likely that this will be seen in the current outcrop. Drilling may be necessary to confirm details of the structure.

Global Earthquake Activity Rate models based on version 2 of the Global Strain Rate Map

NASA Astrophysics Data System (ADS)

Bird, P.; Kreemer, C.; Kagan, Y. Y.; Jackson, D. D.

2013-12-01

Global Earthquake Activity Rate (GEAR) models have usually been based on either relative tectonic motion (fault slip rates and/or distributed strain rates), or on smoothing of seismic catalogs. However, a hybrid approach appears to perform better than either parent, at least in some retrospective tests. First, we construct a Tectonic ('T') forecast of shallow (≤ 70 km) seismicity based on global plate-boundary strain rates from version 2 of the Global Strain Rate Map. Our approach is the SHIFT (Seismic Hazard Inferred From Tectonics) method described by Bird et al. [2010, SRL], in which the character of the strain rate tensor (thrusting and/or strike-slip and/or normal) is used to select the most comparable type of plate boundary for calibration of the coupled seismogenic lithosphere thickness and corner magnitude. One difference is that activity of offshore plate boundaries is spatially smoothed using empirical half-widths [Bird & Kagan, 2004, BSSA] before conversion to seismicity. Another is that the velocity-dependence of coupling in subduction and continental-convergent boundaries [Bird et al., 2009, BSSA] is incorporated. Another forecast component is the smoothed-seismicity ('S') forecast model of [Kagan & Jackson, 1994, JGR; Kagan & Jackson, 2010, GJI], which was based on optimized smoothing of the shallow part of the GCMT catalog, years 1977-2004. Both forecasts were prepared for threshold magnitude 5.767. Then, we create hybrid forecasts by one of 3 methods: (a) taking the greater of S or T; (b) simple weighted-average of S and T; or (c) log of the forecast rate is a weighted average of the logs of S and T. In methods (b) and (c) there is one free parameter, which is the fractional contribution from S. All hybrid forecasts are normalized to the same global rate. Pseudo-prospective tests for 2005-2012 (using versions of S and T calibrated on years 1977-2004) show that many hybrid models outperform both parents (S and T), and that the optimal weight on S is in the neighborhood of 5/8. This is true whether forecast performance is scored by Kagan's [2009, GJI] I1 information score, or by the S-test of Zechar & Jordan [2010, BSSA]. These hybrids also score well (0.97) in the ASS-test of Zechar & Jordan [2008, GJI] with respect to prior relative intensity.

The Demonstrator for the European Plate Observing System (EPOS)

NASA Astrophysics Data System (ADS)

Hoffmann, T. L.; Euteneuer, F.; Ulbricht, D.; Lauterjung, J.; Bailo, D.; Jeffery, K. G.

2014-12-01

An important outcome of the 4-year Preparatory Phase of the ESFRI project European Plate Observing System (EPOS) was the development and first implementation of the EPOS Demonstrator by the project's ICT Working Group 7. The Demonstrator implements the vertical integration of the three-layer architectural scheme for EPOS, connecting the Integrated Core Services (ICS), Thematic Core Services (TCS) and the National Research Infrastructures (NRI). The demonstrator provides a single GUI with central key discovery and query functionalities, based on already existing services by the seismic, geologic and geodetic communities. More specifically the seismic services of the Demonstrator utilize webservices and APIs for data and discovery of raw seismic data (FDSN webservices by the EIDA Network), events (Geoportal by EMSC) and analytical data products (e.g., hazard maps by EFEHR via OGC WMS). For geologic services, the EPOS Demonstrator accesses OneGeology Europe which serves the community with geologic maps and point information via OGC webservices. The Demonstrator also provides access to raw geodetic data via a newly developed universal tool called GSAC. The Demonstrator itself resembles the future Integrated Core Service (ICS) and provides direct access to the end user. Its core functionality lies in a metadata catalogue, which serves as the central information hub and stores information about all RIs, related persons, projects, financial background and technical access information. The database schema of the catalogue is based on CERIF, which has been slightly adapted. Currently, the portal provides basic query functions as well as cross domain search. [www.epos.cineca.it

Probabilistic seismic hazard at the archaeological site of Gol Gumbaz in Vijayapura, south India

NASA Astrophysics Data System (ADS)

Patil, Shivakumar G.; Menon, Arun; Dodagoudar, G. R.

2018-03-01

Probabilistic seismic hazard analysis (PSHA) is carried out for the archaeological site of Vijayapura in south India in order to obtain hazard consistent seismic input ground-motions for seismic risk assessment and design of seismic protection measures for monuments, where warranted. For this purpose the standard Cornell-McGuire approach, based on seismogenic zones with uniformly distributed seismicity is employed. The main features of this study are the usage of an updated and unified seismic catalogue based on moment magnitude, new seismogenic source models and recent ground motion prediction equations (GMPEs) in logic tree framework. Seismic hazard at the site is evaluated for level and rock site condition with 10% and 2% probabilities of exceedance in 50 years, and the corresponding peak ground accelerations (PGAs) are 0.074 and 0.142 g, respectively. In addition, the uniform hazard spectra (UHS) of the site are compared to the Indian code-defined spectrum. Comparisons are also made with results from National Disaster Management Authority (NDMA 2010), in terms of PGA and pseudo spectral accelerations (PSAs) at T = 0.2, 0.5, 1.0 and 1.25 s for 475- and 2475-yr return periods. Results of the present study are in good agreement with the PGA calculated from isoseismal map of the Killari earthquake, {M}w = 6.4 (1993). Disaggregation of PSHA results for the PGA and spectral acceleration ({S}a) at 0.5 s, displays the controlling scenario earthquake for the study region as low to moderate magnitude with the source being at a short distance from the study site. Deterministic seismic hazard (DSHA) is also carried out by taking into account three scenario earthquakes. The UHS corresponding to 475-yr return period (RP) is used to define the target spectrum and accordingly, the spectrum-compatible natural accelerograms are selected from the suite of recorded accelerograms.

The assessment of seismic hazard for Gori, (Georgia) and preliminary studies of seismic microzonation

NASA Astrophysics Data System (ADS)

Gogoladze, Z.; Moscatelli, M.; Giallini, S.; Avalle, A.; Gventsadze, A.; Kvavadze, N.; Tsereteli, N.

2016-12-01

Seismic risk is a crucial issue for South Caucasus, which is the main gateway between Asia and Europe. The goal of this work is to propose new methods and criteria for defining an overall approach aimed at assessing and mitigating seismic risk in Georgia. In this reguard seismic microzonation represents a highly useful tool for seismic risk assessmentin land management, for design of buildings or structures and for emergency planning.Seismic microzonation assessment of local seismic hazard,which is a component of seismicity resulting from specific local characteristics which cause local amplification and soil instability, through identification of zones with seismically homogeneous behavior. This paper presents the results of preliminary study of seismic microzonation of Gori, Georgia. Gori is and is located in the Shida Kartli region and on both sides of Liachvi and Mtkvari rivers, with area of about 135 km2around the Gori fortress. Gori is located in Achara-Trialeti fold-thrust belt, that is tectonically unstable. Half of all earthquakes in Gori area with magnitude M≥3.5 have happened along this fault zone and on basis of damage caused by previous earthquakes, this territory show the highest level of risk (the maximum value of direct losses) in central part of the town. The seismic microzonation map of level 1 for Gori was carried out using: 1) Already available data (i.e., topographic map and boreholes data), 2) Results of new geological surveys and 3) Geophysical measurements (i.e., MASW and noise measurements processed with HVSR technique). Our preliminary results highlight the presence of both stable zones susceptible to local amplifications and unstable zones susceptible to geological instability. Our results are directed to establish set of actions aimed at risk mitigation before initial onset of emergency, and to management of the emergency once the seismic event has occurred. The products obtained, will contain the basic elements of an integrated system aimed at reducing risk and improving over all safety of people and infrastructure in Georgia.

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

Not Available

Greenland's Mineral Resources Administration (MRA) plans a series of licensing rounds off western Greenland. Meanwhile, the MRA has declared the Jameson Land basin of east central Greenland as open acreage. Greenland Geological Survey (GGU), Copenhagen, has prepared a report on the geographical conditions, logistics, exploration history, and geological development of Jameson Land. The article emphasizes source and reservoir rocks, conceptual play types with six seismic examples, and thermal history with basin modeling. It also includes two interpreted regional seismic lines, a geological and an aeromagnetic map, depth structure, and isopach maps of selected formations.

A spatio-temporal model for probabilistic seismic hazard zonation of Tehran

NASA Astrophysics Data System (ADS)

Hashemi, Mahdi; Alesheikh, Ali Asghar; Zolfaghari, Mohammad Reza

2013-08-01

A precondition for all disaster management steps, building damage prediction, and construction code developments is a hazard assessment that shows the exceedance probabilities of different ground motion levels at a site considering different near- and far-field earthquake sources. The seismic sources are usually categorized as time-independent area sources and time-dependent fault sources. While the earlier incorporates the small and medium events, the later takes into account only the large characteristic earthquakes. In this article, a probabilistic approach is proposed to aggregate the effects of time-dependent and time-independent sources on seismic hazard. The methodology is then applied to generate three probabilistic seismic hazard maps of Tehran for 10%, 5%, and 2% exceedance probabilities in 50 years. The results indicate an increase in peak ground acceleration (PGA) values toward the southeastern part of the study area and the PGA variations are mostly controlled by the shear wave velocities across the city. In addition, the implementation of the methodology takes advantage of GIS capabilities especially raster-based analyses and representations. During the estimation of the PGA exceedance rates, the emphasis has been placed on incorporating the effects of different attenuation relationships and seismic source models by using a logic tree.

Geology of the Cape Mendocino, Eureka, Garberville, and Southwestern Part of the Hayfork 30 x 60 Minute Quadrangles and Adjacent Offshore Area, Northern California

USGS Publications Warehouse

McLaughlin, Robert J.; Ellen, S.D.; Blake, M.C.; Jayko, Angela S.; Irwin, W.P.; Aalto, K.R.; Carver, G.A.; Clarke, S.H.; Barnes, J.B.; Cecil, J.D.; Cyr, K.A.

2000-01-01

Introduction These geologic maps and accompanying structure sections depict the geology and structure of much of northwestern California and the adjacent continental margin. The map area includes the Mendocino triple junction, which is the juncture of the North American continental plate with two plates of the Pacific ocean basin. The map area also encompasses major geographic and geologic provinces of northwestern California. The maps incorporate much previously unpublished geologic mapping done between 1980 and 1995, as well as published mapping done between about 1950 and 1978. To construct structure sections to mid-crustal depths, we integrate the surface geology with interpretations of crustal structure based on seismicity, gravity and aeromagnetic data, offshore structure, and seismic reflection and refraction data. In addition to describing major geologic and structural features of northwestern California, the geologic maps have the potential to address a number of societally relevant issues, including hazards from earthquakes, landslides, and floods and problems related to timber harvest, wildlife habitat, and changing land use. All of these topics will continue to be of interest in the region, as changing land uses and population density interact with natural conditions. In these interactions, it is critical that the policies and practices affecting man and the environment integrate an adequate understanding of the geology. This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (ceghmf.ps, ceghmf.pdf, ceghmf.txt), it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:100,000 or smaller.

National Seabed Mapping Programmes Collaborate to Advance Marine Geomorphological Mapping in Adjoining European Seas

NASA Astrophysics Data System (ADS)

Monteys, X.; Guinan, J.; Green, S.; Gafeira, J.; Dove, D.; Baeten, N. J.; Thorsnes, T.

2017-12-01

Marine geomorphological mapping is an effective means of characterising and understanding the seabed and its features with direct relevance to; offshore infrastructure placement, benthic habitat mapping, conservation & policy, marine spatial planning, fisheries management and pure research. Advancements in acoustic survey techniques and data processing methods resulting in the availability of high-resolution marine datasets e.g. multibeam echosounder bathymetry and shallow seismic mean that geological interpretations can be greatly improved by combining with geomorphological maps. Since December 2015, representatives from the national seabed mapping programmes of Norway (MAREANO), Ireland (INFOMAR) and the United Kingdom (MAREMAP) have collaborated and established the MIM geomorphology working group) with the common aim of advancing best practice for geological mapping in their adjoining sea areas in north-west Europe. A recently developed two-part classification system for Seabed Geomorphology (`Morphology' and Geomorphology') has been established as a result of an initiative led by the British Geological Survey (BGS) with contributions from the MIM group (Dove et al. 2016). To support the scheme, existing BGS GIS tools (SIGMA) have been adapted to apply this two-part classification system and here we present on the tools effectiveness in mapping geomorphological features, along with progress in harmonising the classification and feature nomenclature. Recognising that manual mapping of seabed features can be time-consuming and subjective, semi-automated approaches for mapping seabed features and improving mapping efficiency is being developed using Arc-GIS based tools. These methods recognise, spatially delineate and morphologically describe seabed features such as pockmarks (Gafeira et al., 2012) and cold-water coral mounds. Such tools utilise multibeam echosounder data or any other bathymetric dataset (e.g. 3D seismic, Geldof et al., 2014) that can produce a depth digital model. The tools have the capability to capture an extensive list of morphological attributes. The MIM geomorphology working group's strategy to develop methods for more efficient marine geomorphological mapping is presented with data examples and case studies showing the latest results.

A computer procedure to analyze seismic data to estimate outcome probabilities in oil exploration, with an initial application in the tabasco region of southeastern Mexico

NASA Astrophysics Data System (ADS)

Berlanga, Juan M.; Harbaugh, John W.

The Tabasco region contains a number of major oilfields, including some of the emerging "giant" oil fields which have received extensive publicity. Fields in the Tabasco region are associated with large geologic structures which are detected readily by seismic surveys. The structures seem to be associated with deepseated movement of salt, and they are complexly faulted. Some structures have as much as 1000 milliseconds relief of seismic lines. A study, interpreting the structure of the area, used initially only a fraction of the total seismic lines That part of Tabasco region that has been studied was surveyed with a close-spaced rectilinear network of seismic lines. A, interpreting the structure of the area, used initially only a fraction of the total seismic data available. The purpose was to compare "predictions" of reflection time based on widely spaced seismic lines, with "results" obtained along more closely spaced lines. This process of comparison simulates the sequence of events in which a reconnaissance network of seismic lines is used to guide a succession of progressively more closely spaced lines. A square gridwork was established with lines spaced at 10 km intervals, and using machine contour maps, compared the results with those obtained with seismic grids employing spacings of 5 and 2.5 km respectively. The comparisons of predictions based on widely spaced lines with observations along closely spaced lines provide information by which an error function can be established. The error at any point can be defined as the difference between the predicted value for that point, and the subsequently observed value at that point. Residuals obtained by fitting third-degree polynomial trend surfaces were used for comparison. The root mean square of the error measurement, (expressed in seconds or milliseconds reflection time) was found to increase more or less linearly with distance from the nearest seismic point. Oil-occurrence probabilities were established on the basis of frequency distributions of trend-surface residuals obtained by fitting and subtracting polynomial trend surfaces from the machine-contoured reflection time maps. We found that there is a strong preferential relationship between the occurrence of petroleum (i.e. its presence versus absence) and particular ranges of trend-surface residual values. An estimate of the probability of oil occurring at any particular geographic point can be calculated on the basis of the estimated trend-surface residual value. This estimate, however, must be tempered by the probable error in the estimate of the residual value provided by the error function. The result, we believe, is a simple but effective procedure for estimating exploration outcome probabilities where seismic data provide the principal form of information in advance of drilling. Implicit in this approach is the comparison between a maturely explored area, for which both seismic and production data are available, and which serves as a statistical "training area", with the "target" area which is undergoing exploration and for which probability forecasts are to be calculated.

Neo-deterministic definition of earthquake hazard scenarios: a multiscale application to India

NASA Astrophysics Data System (ADS)

Peresan, Antonella; Magrin, Andrea; Parvez, Imtiyaz A.; Rastogi, Bal K.; Vaccari, Franco; Cozzini, Stefano; Bisignano, Davide; Romanelli, Fabio; Panza, Giuliano F.; Ashish, Mr; Mir, Ramees R.

2014-05-01

The development of effective mitigation strategies requires scientifically consistent estimates of seismic ground motion; recent analysis, however, showed that the performances of the classical probabilistic approach to seismic hazard assessment (PSHA) are very unsatisfactory in anticipating ground shaking from future large earthquakes. Moreover, due to their basic heuristic limitations, the standard PSHA estimates are by far unsuitable when dealing with the protection of critical structures (e.g. nuclear power plants) and cultural heritage, where it is necessary to consider extremely long time intervals. Nonetheless, the persistence in resorting to PSHA is often explained by the need to deal with uncertainties related with ground shaking and earthquakes recurrence. We show that current computational resources and physical knowledge of the seismic waves generation and propagation processes, along with the improving quantity and quality of geophysical data, allow nowadays for viable numerical and analytical alternatives to the use of PSHA. The advanced approach considered in this study, namely the NDSHA (neo-deterministic seismic hazard assessment), is based on the physically sound definition of a wide set of credible scenario events and accounts for uncertainties and earthquakes recurrence in a substantially different way. The expected ground shaking due to a wide set of potential earthquakes is defined by means of full waveforms modelling, based on the possibility to efficiently compute synthetic seismograms in complex laterally heterogeneous anelastic media. In this way a set of scenarios of ground motion can be defined, either at national and local scale, the latter considering the 2D and 3D heterogeneities of the medium travelled by the seismic waves. The efficiency of the NDSHA computational codes allows for the fast generation of hazard maps at the regional scale even on a modern laptop computer. At the scenario scale, quick parametric studies can be easily performed to understand the influence of the model characteristics on the computed ground shaking scenarios. For massive parametric tests, or for the repeated generation of large scale hazard maps, the methodology can take advantage of more advanced computational platforms, ranging from GRID computing infrastructures to HPC dedicated clusters up to Cloud computing. In such a way, scientists can deal efficiently with the variety and complexity of the potential earthquake sources, and perform parametric studies to characterize the related uncertainties. NDSHA provides realistic time series of expected ground motion readily applicable for seismic engineering analysis and other mitigation actions. The methodology has been successfully applied to strategic buildings, lifelines and cultural heritage sites, and for the purpose of seismic microzoning in several urban areas worldwide. A web application is currently being developed that facilitates the access to the NDSHA methodology and the related outputs by end-users, who are interested in reliable territorial planning and in the design and construction of buildings and infrastructures in seismic areas. At the same, the web application is also shaping up as an advanced educational tool to explore interactively how seismic waves are generated at the source, propagate inside structural models, and build up ground shaking scenarios. We illustrate the preliminary results obtained from a multiscale application of NDSHA approach to the territory of India, zooming from large scale hazard maps of ground shaking at bedrock, to the definition of local scale earthquake scenarios for selected sites in the Gujarat state (NW India). The study aims to provide the community (e.g. authorities and engineers) with advanced information for earthquake risk mitigation, which is particularly relevant to Gujarat in view of the rapid development and urbanization of the region.

Seismic Landslide Hazard for the City of Berkeley, California

USGS Publications Warehouse

Miles, Scott B.; Keefer, David K.

2001-01-01

This map describes the possible hazard from earthquake-induced landslides for the city of Berkeley, CA. The hazard depicted by this map was modeled for a scenario corresponding to an M=7.1 earthquake on the Hayward, CA fault. This scenario magnitude is associated with complete rupture of the northern and southern segments of the Hayward fault, an event that has an estimated return period of about 500 years. The modeled hazard also corresponds to completely saturated ground-water conditions resulting from an extreme storm event or series of storm events. This combination of earthquake and ground-water scenarios represents a particularly severe state of hazard for earthquake-induced landslides. For dry ground-water conditions, overall hazard will be less, while relative patterns of hazard are likely to change. Purpose: The map is intended as a tool for regional planning. Any site-specific planning or analysis should be undertaken with the assistance of a qualified geotechnical engineer. This hazard map should not be used as a substitute to the State of California Seismic Hazard Zones map for the same area. (See California Department of Conservation, Division of Mines and Geology, 1999). As previously noted for maps of this type by Wieczorek and others (1985), this map should not be used as a basis to determine the absolute risk from seismically triggered landslides at any locality, as the sole justification for zoning or rezoning any parcel, for detailed design of any lifeline, for site-specific hazard-reduction planning, or for setting or modifying insurance rates.

Shear wave velocity, seismic attenuation, and thermal structure of the continental upper mantle

USGS Publications Warehouse

Artemieva, I.M.; Billien, M.; Leveque, J.-J.; Mooney, W.D.

2004-01-01

Seismic velocity and attenuation anomalies in the mantle are commonly interpreted in terms of temperature variations on the basis of laboratory studies of elastic and anelastic properties of rocks. In order to evaluate the relative contributions of thermal and non-thermal effects on anomalies of attenuation of seismic shear waves, QS-1, and seismic velocity, VS, we compare global maps of the thermal structure of the continental upper mantle with global QS-1 and Vs maps as determined from Rayleigh waves at periods between 40 and 150 S. We limit the comparison to three continental mantle depths (50, 100 and 150 km), where model resolution is relatively high. The available data set does not indicate that, at a global scale, seismic anomalies in the upper mantle are controlled solely by temperature variations. Continental maps have correlation coefficients of <0.56 between VS and T and of <0.47 between QS and T at any depth. Such low correlation coefficients can partially be attributed to modelling arrefacts; however, they also suggest that not all of the VS and QS anomalies in the continental upper mantle can be explained by T variations. Global maps show that, by the sign of the anomaly, VS and QS usually inversely correlate with lithospheric temperatures: most cratonic regions show high VS and QS and low T, while most active regions have seismic and thermal anomalies of the opposite sign. The strongest inverse correlation is found at a depth of 100 km, where the attenuation model is best resolved. Significantly, at this depth, the contours of near-zero QS anomalies approximately correspond to the 1000 ??C isotherm, in agreement with laboratory measurements that show a pronounced increase in seismic attenuation in upper mantle rocks at 1000-1100 ??C. East-west profiles of VS, QS and T where continental data coverage is best (50??N latitude for North America and 60??N latitude for Eurasia) further demonstrate that temperature plays a dominant, but non-unique, role in determining the value of lithospheric VS and QS. At 100 km depth, where the resolution of seismic models is the highest, we compare observed seismic VS and QS with theoretical VST and QST values, respectively, that are calculated solely from temperature anomalies and constrained by experimental data on temperature dependencies of velocity and attenuation. This comparison shows that temperature variations alone are sufficient to explain seismic VS and QS in ca 50 per cent of continental regions. We hypothesize that compositional anomalies resulting from Fe depletion can explain the misfit between seismic and theoretical VS in cratonic lithosphere. In regions of active tectonics, temperature effects alone cannot explain seismic VS and QS in the lithosphere. It is likely that partial melts and/or fluids may affect seismic parameters in these regions. This study demonstrates that lithospheric temperature plays the dominant role in controlling VS and QS anomalies, but other physical parameters, such as compositional variations, fluids, partial melting and scattering, may also play a significant role in determining VS and QS variations in the continental mantle. ?? 2004 RAS.

Multi scenario seismic hazard assessment for Egypt

NASA Astrophysics Data System (ADS)

Mostafa, Shaimaa Ismail; Abd el-aal, Abd el-aziz Khairy; El-Eraki, Mohamed Ahmed

2018-01-01

Egypt is located in the northeastern corner of Africa within a sensitive seismotectonic location. Earthquakes are concentrated along the active tectonic boundaries of African, Eurasian, and Arabian plates. The study area is characterized by northward increasing sediment thickness leading to more damage to structures in the north due to multiple reflections of seismic waves. Unfortunately, man-made constructions in Egypt were not designed to resist earthquake ground motions. So, it is important to evaluate the seismic hazard to reduce social and economic losses and preserve lives. The probabilistic seismic hazard assessment is used to evaluate the hazard using alternative seismotectonic models within a logic tree framework. Alternate seismotectonic models, magnitude-frequency relations, and various indigenous attenuation relationships were amended within a logic tree formulation to compute and develop the regional exposure on a set of hazard maps. Hazard contour maps are constructed for peak ground acceleration as well as 0.1-, 0.2-, 0.5-, 1-, and 2-s spectral periods for 100 and 475 years return periods for ground motion on rock. The results illustrate that Egypt is characterized by very low to high seismic activity grading from the west to the eastern part of the country. The uniform hazard spectra are estimated at some important cities distributed allover Egypt. The deaggregation of seismic hazard is estimated at some cities to identify the scenario events that contribute to a selected seismic hazard level. The results of this study can be used in seismic microzonation, risk mitigation, and earthquake engineering purposes.

Precursory seismic quiescence along the Sumatra-Andaman subduction zone: past and present

NASA Astrophysics Data System (ADS)

Sukrungsri, Santawat; Pailoplee, Santi

2017-03-01

In this study, the seismic quiescence prior to hazardous earthquakes was analyzed along the Sumatra-Andaman subduction zone (SASZ). The seismicity data were screened statistically with mainshock earthquakes of M w ≥ 4.4 reported during 1980-2015 being defined as the completeness database. In order to examine the possibility of using the seismic quiescence stage as a marker of subsequent earthquakes, the seismicity data reported prior to the eight major earthquakes along the SASZ were analyzed for changes in their seismicity rate using the statistical Z test. Iterative tests revealed that Z factors of N = 50 events and T = 2 years were optimal for detecting sudden rate changes such as quiescence and to map these spatially. The observed quiescence periods conformed to the subsequent major earthquake occurrences both spatially and temporally. Using suitable conditions obtained from successive retrospective tests, the seismicity rate changes were then mapped from the most up-to-date seismicity data available. This revealed three areas along the SASZ that might generate a major earthquake in the future: (i) Nicobar Islands ( Z = 6.7), (ii) the western offshore side of Sumatra Island ( Z = 7.1), and (iii) western Myanmar ( Z = 6.7). The performance of a stochastic test using a number of synthetic randomized catalogues indicated these levels of anomalous Z value showed the above anomaly is unlikely due to chance or random fluctuations of the earthquake. Thus, these three areas have a high possibility of generating a strong-to-major earthquake in the future.

Multi scenario seismic hazard assessment for Egypt

NASA Astrophysics Data System (ADS)

Mostafa, Shaimaa Ismail; Abd el-aal, Abd el-aziz Khairy; El-Eraki, Mohamed Ahmed

2018-05-01

Egypt is located in the northeastern corner of Africa within a sensitive seismotectonic location. Earthquakes are concentrated along the active tectonic boundaries of African, Eurasian, and Arabian plates. The study area is characterized by northward increasing sediment thickness leading to more damage to structures in the north due to multiple reflections of seismic waves. Unfortunately, man-made constructions in Egypt were not designed to resist earthquake ground motions. So, it is important to evaluate the seismic hazard to reduce social and economic losses and preserve lives. The probabilistic seismic hazard assessment is used to evaluate the hazard using alternative seismotectonic models within a logic tree framework. Alternate seismotectonic models, magnitude-frequency relations, and various indigenous attenuation relationships were amended within a logic tree formulation to compute and develop the regional exposure on a set of hazard maps. Hazard contour maps are constructed for peak ground acceleration as well as 0.1-, 0.2-, 0.5-, 1-, and 2-s spectral periods for 100 and 475 years return periods for ground motion on rock. The results illustrate that Egypt is characterized by very low to high seismic activity grading from the west to the eastern part of the country. The uniform hazard spectra are estimated at some important cities distributed allover Egypt. The deaggregation of seismic hazard is estimated at some cities to identify the scenario events that contribute to a selected seismic hazard level. The results of this study can be used in seismic microzonation, risk mitigation, and earthquake engineering purposes.

Geologic interpretation and multibeam bathymetry of the sea floor in southeastern Long Island Sound

USGS Publications Warehouse

Poppe, Lawrence J.; Ackerman, Seth D.; Doran, Elizabeth F.; Moser, Marc S.; Stewart, Helen F.; Forfinski, Nicholas A.; Gardner, Uther L.; Keene, Jennifer A.

2006-01-01

Digital terrain models (DTMs) produced from multibeam echosounder (MBES) bathymetric data provide valuable base maps for marine geological interpretations (e.g. Todd and others, 1999; Mosher and Thomson, 2002; ten Brink and others, 2004; Poppe and others, 2006a,b). These maps help define the geological variability of the sea floor (one of the primary controls of benthic habitat diversity); improve our understanding of the processes that control the distribution and transport of bottom sediments, the distribution of benthic habitats and associated infaunal community structures; and provide a detailed framework for future research, monitoring, and management activities. The bathymetric survey interpreted herein (National Oceanic and Atmospheric Administration (NOAA) survey H11255) covers roughly 95 km? of sea floor in southeastern Long Island Sound (fig. 1). This bathymetry has been examined in relation to seismic reflection data collected concurrently, as well as archived seismic profiles acquired as part of a long-standing geologic mapping partnership between the State of Connecticut and the U.S. Geological Survey (USGS). The objective of this work was to use these geophysical data sets to interpret geomorphological attributes of the sea floor in terms of the Quaternary geologic history and modern sedimentary processes within Long Island Sound.

U.S. Geological Survery Oil and Gas Resource Assessment of the Russian Arctic

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

Donald Gautier; Timothy Klett

2008-12-31

The U.S. Geological Survey (USGS) recently completed a study of undiscovered petroleum resources in the Russian Arctic as a part of its Circum-Arctic Resource Appraisal (CARA), which comprised three broad areas of work: geological mapping, basin analysis, and quantitative assessment. The CARA was a probabilistic, geologically based study that used existing USGS methodology, modified somewhat for the circumstances of the Arctic. New map compilation was used to identify assessment units. The CARA relied heavily on geological analysis and analog modeling, with numerical input consisting of lognormal distributions of sizes and numbers of undiscovered accumulations. Probabilistic results for individual assessment unitsmore » were statistically aggregated, taking geological dependencies into account. The U.S. Department of Energy (DOE) funds were used to support the purchase of crucial seismic data collected in the Barents Sea, East Siberian Sea, and Chukchi Sea for use by USGS in its assessment of the Russian Arctic. DOE funds were also used to purchase a commercial study, which interpreted seismic data from the northern Kara Sea, and for geographic information system (GIS) support of USGS mapping of geological features, province boundaries, total petroleum systems, and assessment units used in the USGS assessment.« less

Multicomponent Seismic Analysis and Calibration to Improve Recovery from Algal Mounds: Application to the Roadrunner/Towaoc area of the Paradox Basin, UTE Mountain UTE Reservation, Colorado

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

Joe Hachey

2007-09-30

The goals of this project were: (1) To enhance recovery of oil contained within algal mounds on the Ute Mountain Ute tribal lands. (2) To promote the use of advanced technology and expand the technical capability of the Native American Oil production corporations by direct assistance in the current project and dissemination of technology to other Tribes. (3) To develop an understanding of multicomponent seismic data as it relates to the variations in permeability and porosity of algal mounds, as well as lateral facies variations, for use in both reservoir development and exploration. (4) To identify any undiscovered algal moundsmore » for field-extension within the area of seismic coverage. (5) To evaluate the potential for applying CO{sub 2} floods, steam floods, water floods or other secondary or tertiary recovery processes to increase production. The technical work scope was carried out by: (1) Acquiring multicomponent seismic data over the project area; (2) Processing and reprocessing the multicomponent data to extract as much geological and engineering data as possible within the budget and time-frame of the project; (3) Preparing maps and data volumes of geological and engineering data based on the multicomponent seismic and well data; (4) Selecting drilling targets if warranted by the seismic interpretation; (5) Constructing a static reservoir model of the project area; and (6) Constructing a dynamic history-matched simulation model from the static model. The original project scope covered a 6 mi{sup 2} (15.6 km{sup 2}) area encompassing two algal mound fields (Towaoc and Roadrunner). 3D3C seismic data was to acquired over this area to delineate mound complexes and image internal reservoir properties such as porosity and fluid saturations. After the project began, the Red Willow Production Company, a project partner and fully-owned company of the Southern Ute Tribe, contributed additional money to upgrade the survey to a nine-component (3D9C) survey. The purpose of this upgrade to nine components was to provide additional shear wave component data that might prove useful in delineating internal mound reservoir attributes. Also, Red Willow extended the P-wave portion of the survey to the northwest of the original 6 mi{sup 2} (15.6 km{sup 2}) 3D9C area in order to extend coverage further to the northwest to the Marble Wash area. In order to accomplish this scope of work, 3D9C seismic data set covering two known reservoirs was acquired and processed. Three-dimensional, zero-offset vertical seismic profile (VSP) data was acquired to determine the shear wave velocities for processing the sh3Dseismic data. Anisotropic velocity, and azimuthal AVO processing was carried out in addition to the conventional 3D P-wave data processing. All P-, PS- and S-wave volumes of the seismic data were interpreted to map the seismic response. The interpretation consisted of conventional cross-plots of seismic attributes vs. geological and reservoir engineering data, as well as multivariate and neural net analyses to assess whether additional resolution on exploration and engineering parameters could be achieved through the combined use of several seismic variables. Engineering data in the two reservoirs was used to develop a combined lithology, structure and permeability map. On the basis of the seismic data, a well was drilled into the northern mound trend in the project area. This well, Roadrunner No.9-2, was brought into production in late April 2006 and continues to produce modest amounts of oil and gas. As of the end of August 2007, the well has produced approximately 12,000 barrels of oil and 32,000 mcf of gas. A static reservoir model was created from the seismic data interpretations and well data. The seismic data was tied to various markers identified in the well logs, which in turn were related to lithostratigraphy. The tops and thicknesses of the various units were extrapolated from well control based upon the seismic data that was calibrated to the well picks. The reservoir engineering properties were available from a number of wells in the project area. Multivariate regressions of seismic attributes versus engineering parameters, such as porosity, were then used to guide interpolation away from well control. These formed the basis for dynamic reservoir simulations. The simulations were used to assess the potential for additional reservoir development, and to provide insight as to how well the multivariate approach worked for assigning more realistic values of internal mound reservoir properties.« less

Use of microcomputer in mapping depth of stratigraphic horizons in National Petroleum Reserve in Alaska

USGS Publications Warehouse

Payne, Thomas G.

1982-01-01

REGIONAL MAPPER is a menu-driven system in the BASIC language for computing and plotting (1) time, depth, and average velocity to geologic horizons, (2) interval time, thickness, and interval velocity of stratigraphic intervals, and (3) subcropping and onlapping intervals at unconformities. The system consists of three programs: FILER, TRAVERSER, and PLOTTER. A control point is a shot point with velocity analysis or a shot point at or near a well with velocity check-shot survey. Reflection time to and code number of seismic horizons are filed by digitizing tablet from record sections. TRAVERSER starts at a point of geologic control and, in traversing to another, parallels seismic events, records loss of horizons by onlap and truncation, and stores reflection time for geologic horizons at traversed shot points. TRAVERSER is basically a phantoming procedure. Permafrost thickness and velocity variations, buried canyons with low-velocity fill, and error in seismically derived velocity cause velocity anomalies that complicate depth mapping. Two depths to the top of the pebble is based shale are computed for each control point. One depth, designated Zs on seismically derived velocity. The other (Zw) is based on interval velocity interpolated linearly between wells and multiplied by interval time (isochron) to give interval thickness. Z w is computed for all geologic horizons by downward summation of interval thickness. Unknown true depth (Z) to the pebble shale may be expressed as Z = Zs + es and Z = Zw + ew where the e terms represent error. Equating the two expressions gives the depth difference D = Zs + Zw = ew + es A plot of D for the top of the pebble shale is readily contourable but smoothing is required to produce a reasonably simple surface. Seismically derived velocity used in computing Zs includes the effect of velocity anomalies but is subject to some large randomly distributed errors resulting in depth errors (es). Well-derived velocity used in computing Zw does not include the effect of velocity anomalies, but the error (ew) should reflect these anomalies and should be contourable (non-random). The D surface as contoured with smoothing is assumed to represent ew, that is, the depth effect of variations in permafrost thickness and velocity and buried canyon depth. Estimated depth (Zest) to each geologic horizon is the sum of Z w for that horizon and a constant e w as contoured for the pebble shale, which is the first highly continuous seismic horizon below the zone of anomalous velocity. Results of this 'depthing' procedure are compared with those of Tetra Tech, Inc., the subcontractor responsible for geologic and geophysical interpretation and mapping.

Estimating annualized earthquake losses for the conterminous United States

USGS Publications Warehouse

Jaiswal, Kishor S.; Bausch, Douglas; Chen, Rui; Bouabid, Jawhar; Seligson, Hope

2015-01-01

We make use of the most recent National Seismic Hazard Maps (the years 2008 and 2014 cycles), updated census data on population, and economic exposure estimates of general building stock to quantify annualized earthquake loss (AEL) for the conterminous United States. The AEL analyses were performed using the Federal Emergency Management Agency's (FEMA) Hazus software, which facilitated a systematic comparison of the influence of the 2014 National Seismic Hazard Maps in terms of annualized loss estimates in different parts of the country. The losses from an individual earthquake could easily exceed many tens of billions of dollars, and the long-term averaged value of losses from all earthquakes within the conterminous U.S. has been estimated to be a few billion dollars per year. This study estimated nationwide losses to be approximately $4.5 billion per year (in 2012$), roughly 80% of which can be attributed to the States of California, Oregon and Washington. We document the change in estimated AELs arising solely from the change in the assumed hazard map. The change from the 2008 map to the 2014 map results in a 10 to 20% reduction in AELs for the highly seismic States of the Western United States, whereas the reduction is even more significant for Central and Eastern United States.

Vulnerability mapping as a tool to manage the environmental impacts of oil and gas extraction.

PubMed

Esterhuyse, Surina; Sokolic, Frank; Redelinghuys, Nola; Avenant, Marinda; Kijko, Andrzej; Glazewski, Jan; Plit, Lisa; Kemp, Marthie; Smit, Ansie; Vos, A Tascha; von Maltitz, Michael J

2017-11-01

Various biophysical and socio-economic impacts may be associated with unconventional oil and gas (UOG) extraction. A vulnerability map may assist governments during environmental assessments, spatial planning and the regulation of UOG extraction, as well as decision-making around UOG extraction in fragile areas. A regional interactive vulnerability map was developed for UOG extraction in South Africa. This map covers groundwater, surface water, vegetation, socio-economics and seismicity as mapping themes, based on impacts that may emanate from UOG extraction. The mapping themes were developed using a normative approach, where expert input during the identification and classification of vulnerability indicators may increase the acceptability of the resultant map. This article describes the development of the interactive vulnerability map for South Africa, where UOG extraction is not yet allowed and where regulations are still being developed to manage this activity. The importance and policy implications of using vulnerability maps for managing UOG extraction impacts in countries where UOG extraction is planned are highlighted in this article.

Vulnerability mapping as a tool to manage the environmental impacts of oil and gas extraction

PubMed Central

Sokolic, Frank; Redelinghuys, Nola; Avenant, Marinda; Kijko, Andrzej; Glazewski, Jan; Plit, Lisa; Kemp, Marthie; Smit, Ansie; Vos, A. Tascha; von Maltitz, Michael J.

2017-01-01

Various biophysical and socio-economic impacts may be associated with unconventional oil and gas (UOG) extraction. A vulnerability map may assist governments during environmental assessments, spatial planning and the regulation of UOG extraction, as well as decision-making around UOG extraction in fragile areas. A regional interactive vulnerability map was developed for UOG extraction in South Africa. This map covers groundwater, surface water, vegetation, socio-economics and seismicity as mapping themes, based on impacts that may emanate from UOG extraction. The mapping themes were developed using a normative approach, where expert input during the identification and classification of vulnerability indicators may increase the acceptability of the resultant map. This article describes the development of the interactive vulnerability map for South Africa, where UOG extraction is not yet allowed and where regulations are still being developed to manage this activity. The importance and policy implications of using vulnerability maps for managing UOG extraction impacts in countries where UOG extraction is planned are highlighted in this article. PMID:29291094

Marine forearc tectonics in the unbroken segment of the Northern Chile seismic gap

NASA Astrophysics Data System (ADS)

Geersen, J.; Behrmann, J.; Ranero, C. R.; Klaucke, I.; Kopp, H.; Lange, D.; Barckhausen, U.; Reichert, C. J.; Diaz-Naveas, J.

2016-12-01

While clearly occurring within the well-defined Northern Chile seismic gap, the 2014 Mw. 8.1 Iquique Earthquake only ruptured part of this gap, leaving large and possibly highly coupled areas untouched. These non-ruptured areas now may pose an elevated seismic hazard due to the transfer of stresses resulting from the 2014 rupture. Here we use recently collected multibeam bathymetric data, covering 90% of the North Chilean marine forearc, in combination with unpublished seismic reflection images to derive a tectonic map of the marine forearc in the unbroken segment of the seismic gap. In the entire study area we find evidence for widespread normal faulting. Seaward dipping normal faults locally extend close to the deformation front at the deep-sea trench under 8 km of water. Similar normal faults on the lower slope are neither observed further north (2014 Iquique earthquake area) nor further south (2007 Tocopilla earthquake area). On the upper continental slope, some of the normal faults dip towards the continent, defining N-S trending ridges that can be traced over tens of kilometers. The spatial variations in normal faulting do not correlate with obvious changes in the structural and tectonic setting of the subduction zone (e.g. plate convergence rate and direction, trench sediment thickness, subducting plate roughness). Thus, the permanent deformation recorded in the spatial distribution of faults may hold crucial information about the long-term seismic behavior of the Northern Chile seismic gap over multiple earthquake cycles. Although the structural interpretations cannot directly be translated into seismic hazard, the tectonic map serves to better understand deformation in the marine forearc in relation to the seismic cycle, historic seismicity, and the spatial distribution of plate-coupling.

Seismic and thermal structure of the crust and uppermost mantle beneath Antarctica from inversion of multiple seismic datasets

NASA Astrophysics Data System (ADS)

Wiens, D.; Shen, W.; Anandakrishnan, S.; Aster, R. C.; Gerstoft, P.; Bromirski, P. D.; Dalziel, I.; Hansen, S. E.; Heeszel, D.; Huerta, A. D.; Nyblade, A.; Stephen, R. A.; Wilson, T. J.; Winberry, J. P.; Stern, T. A.

2017-12-01

Since the last decade of the 20th century, over 200 broadband seismic stations have been deployed across Antarctica (e.g., temporary networks such as TAMSEIS, AGAP/GAMSEIS, POLENET/ANET, TAMNNET and RIS/DRIS by U.S. geoscientists as well as stations deployed by Japan, Britain, China, Norway, and other countries). In this presentation, we discuss our recent efforts to build reference crustal and uppermost mantle shear velocity (Vs) and thermal models for continental Antarctica based on those seismic arrays. By combing the high resolution Rayleigh wave dispersion maps derived from both ambient noise and teleseismic earthquakes, together with P receiver function waveforms, we develop a 3-D Vs model for the crust and uppermost mantle beneath Central and West Antarctica to a depth of 200 km. Additionally, using this 3-D seismic model to constrain the crustal structure, we re-invert for the upper mantle thermal structure using the surface wave data within a thermodynamic framework and construct a 3-D thermal model for the Antarctic lithosphere. The final product, a high resolution thermal model together with associated uncertainty estimates from the Monte Carlo inversion, allows us to derive lithospheric thickness and surface heat flux maps for much of the continent. West Antarctica shows a much thinner lithosphere ( 50-90 km) than East Antarctica ( 130-230 km), with a sharp transition along the Transantarctic Mountains (TAM). A variety of geological features, including a slower/hotter but highly heterogeneous West Antarctica and a much faster/colder East Antarctic craton, are present in the 3-D seismic/thermal models. Notably, slow seismic velocities observed in the uppermost mantle beneath the southern TAM are interpreted as a signature of lithospheric foundering and replacement with hot asthenosphere. The high resolution image of these features from the 3-D models helps further investigation of the dynamic state of Antarctica's lithosphere and underlying asthenosphere and provides key constraints on the interaction between the solid Earth and the West Antarctic Ice Sheet.

Landslides triggered by the January 12, 2010 Port-au-Prince, Haiti Mw 7.0 earthquake

NASA Astrophysics Data System (ADS)

Xu, Chong

2014-05-01

The January 12, 2010 Port-au-Prince, Haiti earthquake (Mw 7.0) triggered tens of thousands of landslides. The purpose of this study is to investigate correlations of the occurrence of landslides and its erosion thickness with topographic factors, seismic parameters, and distance from roads. A total of 30,828 landslides triggered by the earthquake cover a total area of 15.736 km2, and the volume of landslide accumulation materials is estimated to be about 30,000,000 m3, and throughout an area more than 3,000 km2. These landslides are of various types, mainly in shallow disrupted landslides and rock falls, and also including coherent deep-seated landslides, shallow disrupted landslides, rock falls, and rock slides. These landslides were delineated using pre- and post-earthquake high-resolutions satellite images. Spatial distribution maps and contour maps of landslide number density, landslide area percentage, and landslide erosion thickness were respectively constructed in order to more intuitive to discover the spatial distribution patterns of the co-seismic landslides. Statistics of size distribution and morphometric parameters of the co-seismic landslides were carried out and were compared with other earthquake events. Four proxies of co-seismic landslides abundances, including landslides centroid number density (LCND), landslide top number density (LTND), landslide area percentage (LAP), and landslide erosion thickness (LET) were used to correlate the co-seismic landslides with various landslide controlling parameters. These controlling parameters include elevation, slope angle, slope aspect, slope curvature, topographic position, distance from drainages, stratum/lithology, distance from the epicenter, distance from the Enriquillo-Plantain Garden fault, distance along the fault, and peak ground acceleration (PGA). Comparing of controls of impact parameters on co-seismic landslides show that slope angle is the strongest impact parameter on co-seismic landslides occurrence. In addition, it should be noted that the co-seismic landslides of our inventories is much more detailed than other inventories in several previous publications. Therefore, comparisons of inventories of landslides triggered by the Haiti earthquake with other published results were carried out and the reasons of such differences were presented. We suggest it should not be limited by past empirical functions between earthquake magnitude and co-seismic landslides or it is necessary to update the past empirical functions based on more and more latest and complete co-seismic landslide inventories. This research was supported by the National Science Foundation of China (41202235)

Crustal interpretation of the MAGSAT data in the continental United States

NASA Technical Reports Server (NTRS)

Won, I. J.; Son, K. H.

1982-01-01

The processing of MAGSAT scalar data to construct a crustal magnetic anomaly map over the continental U.S. involves removal of the reference field model, a path-by-path subtraction of a low order polynomial through a least-squares fit to reduce orbital offset errors, and a two dimensional spectral filtering to mitigate the spectral bias induced by the path-by-path orbital correction scheme. The resultant anomaly map shows reasonably good correlations with an aeromagnetic map derived from the project MAGNET. Prominent satellite magnetic anomalies are identified in terms of geological provinces and age boundaries. An inversion method was applied to MAGSAT data which produces both the Curie depth topography and laterally varying magnetic susceptibility of the crust. A contoured Curie depth map thus derived shows general agreements with a crustal thickness map based on seismic data.

Geological and Seismic Data Mining For The Development of An Interpretation System Within The Alptransit Project

NASA Astrophysics Data System (ADS)

Klose, C. D.; Giese, R.; Löw, S.; Borm, G.

Especially for deep underground excavations, the prediction of the locations of small- scale hazardous geotechnical structures is nearly impossible when exploration is re- stricted to surface based methods. Hence, for the AlpTransit base tunnels, exploration ahead has become an essential component of the excavation plan. The project de- scribed in this talk aims at improving the technology for the geological interpretation of reflection seismic data. The discovered geological-seismic relations will be used to develop an interpretation system based on artificial intelligence to predict hazardous geotechnical structures of the advancing tunnel face. This talk gives, at first, an overview about the data mining of geological and seismic properties of metamorphic rocks within the Penninic gneiss zone in Southern Switzer- land. The data results from measurements of a specific geophysical prediction system developed by the GFZ Potsdam, Germany, along the 2600 m long and 1400 m deep Faido access tunnel. The goal is to find those seismic features (i.e. compression and shear wave velocities, velocity ratios and velocity gradients) which show a significant relation to geological properties (i.e. fracturing and fabric features). The seismic properties were acquired from different tomograms, whereas the geolog- ical features derive from tunnel face maps. The features are statistically compared with the seismic rock properties taking into account the different methods used for the tunnel excavation (TBM and Drill/Blast). Fracturing and the mica content stay in a positive relation to the velocity values. Both, P- and S-wave velocities near the tunnel surface describe the petrology better, whereas in the interior of the rock mass they correlate to natural micro- and macro-scopic fractures surrounding tectonites, i.e. cataclasites. The latter lie outside of the excavation damage zone and the tunnel loos- ening zone. The shear wave velocities are better indicators for rock fracturing than compression wave velocities. The velocity ratios indicate the mica content and the water content of the rocks.

A reference model for crust and uppermost mantle beneath Antarctica

NASA Astrophysics Data System (ADS)

Shen, W.; Wiens, D.; Gerstoft, P.; Bromirski, P. D.; Stephen, R. A.; Aster, R. C.; Nyblade, A.; Winberry, J. P.; Huerta, A. D.; Anandakrishnan, S.; Hansen, S. E.; Wilson, T. J.; Heeszel, D.

2016-12-01

Since the last decade of the 20th Century, over 300 broad-band seismic stations have been deployed across the continent of Antarctica (e.g., temporary networks such as TAMSEIS, AGAP/GAMSEIS, POLENET/ANET, TAMNNET and RIS/DRIS by US geoscientists, as well as stations deployed by other countries). In this presentation, we discuss our recent effort that builds a reference crustal and uppermost mantle shear velocity (Vs) model for continental Antarctica based on those seismic arrays. The data analysis for this effort consists of four steps. First, we compute ambient noise cross-correlations between all possible station pairs and use them to construct Rayleigh wave phase and group velocity maps at a continental scale. Coherence of the new maps with maps generated from teleseismic earthquake data from an earlier study (Heeszel et al., 2016) confirms the high quality of both maps and the minor difference helps quantify the map uncertainties. Second, we compute P receiver function waveforms for each station in Antarctica. Third, we collect Rayleigh waves generated by teleseismic earthquakes and measure their horizontal to vertical (H/V) ratio at each station. Fourth and finally, by combing all seismic measurements from the first three steps together with the phase velocity maps by Heeszel et al.(2016) using a non-linear Monte Carlo (MC) inversion algorithm, we built a 3-D model for the crust and uppermost mantle beneath continental Antarctica and its periphery to a depth of 150 km. This high resolution model, together with associated uncertainty estimates from the MC inversion, serve as a starting point for further improvement and geological interpretation. A variety of tectonic features, including a slower but highly heterogeneous West Antarctica and a much faster East Antarctica, are present in the 3D model. A better image of these features from the 3D model helps further investigation of the thermal and dynamic state of Antarctica's lithosphere and underlying asthenosphere and provides key constraints on the interaction of the solid earth with the West Antarctic Ice Sheet.

Seismic hazard estimation of northern Iran using smoothed seismicity

NASA Astrophysics Data System (ADS)

Khoshnevis, Naeem; Taborda, Ricardo; Azizzadeh-Roodpish, Shima; Cramer, Chris H.

2017-07-01

This article presents a seismic hazard assessment for northern Iran, where a smoothed seismicity approach has been used in combination with an updated seismic catalog and a ground motion prediction equation recently found to yield good fit with data. We evaluate the hazard over a geographical area including the seismic zones of Azerbaijan, the Alborz Mountain Range, and Kopeh-Dagh, as well as parts of other neighboring seismic zones that fall within our region of interest. In the chosen approach, seismic events are not assigned to specific faults but assumed to be potential seismogenic sources distributed within regular grid cells. After performing the corresponding magnitude conversions, we decluster both historical and instrumental seismicity catalogs to obtain earthquake rates based on the number of events within each cell, and smooth the results to account for the uncertainty in the spatial distribution of future earthquakes. Seismicity parameters are computed for each seismic zone separately, and for the entire region of interest as a single uniform seismotectonic region. In the analysis, we consider uncertainties in the ground motion prediction equation, the seismicity parameters, and combine the resulting models using a logic tree. The results are presented in terms of expected peak ground acceleration (PGA) maps and hazard curves at selected locations, considering exceedance probabilities of 2 and 10% in 50 years for rock site conditions. According to our results, the highest levels of hazard are observed west of the North Tabriz and east of the North Alborz faults, where expected PGA values are between about 0.5 and 1 g for 10 and 2% probability of exceedance in 50 years, respectively. We analyze our results in light of similar estimates available in the literature and offer our perspective on the differences observed. We find our results to be helpful in understanding seismic hazard for northern Iran, but recognize that additional efforts are necessary to obtain more robust estimates at specific areas of interest and different site conditions.

A Probabilistic Approach to Network Event Formation from Pre-Processed Waveform Data

NASA Astrophysics Data System (ADS)

Kohl, B. C.; Given, J.

2017-12-01

The current state of the art for seismic event detection still largely depends on signal detection at individual sensor stations, including picking accurate arrivals times and correctly identifying phases, and relying on fusion algorithms to associate individual signal detections to form event hypotheses. But increasing computational capability has enabled progress toward the objective of fully utilizing body-wave recordings in an integrated manner to detect events without the necessity of previously recorded ground truth events. In 2011-2012 Leidos (then SAIC) operated a seismic network to monitor activity associated with geothermal field operations in western Nevada. We developed a new association approach for detecting and quantifying events by probabilistically combining pre-processed waveform data to deal with noisy data and clutter at local distance ranges. The ProbDet algorithm maps continuous waveform data into continuous conditional probability traces using a source model (e.g. Brune earthquake or Mueller-Murphy explosion) to map frequency content and an attenuation model to map amplitudes. Event detection and classification is accomplished by combining the conditional probabilities from the entire network using a Bayesian formulation. This approach was successful in producing a high-Pd, low-Pfa automated bulletin for a local network and preliminary tests with regional and teleseismic data show that it has promise for global seismic and nuclear monitoring applications. The approach highlights several features that we believe are essential to achieving low-threshold automated event detection: Minimizes the utilization of individual seismic phase detections - in traditional techniques, errors in signal detection, timing, feature measurement and initial phase ID compound and propagate into errors in event formation, Has a formalized framework that utilizes information from non-detecting stations, Has a formalized framework that utilizes source information, in particular the spectral characteristics of events of interest, Is entirely model-based, i.e. does not rely on a priori's - particularly important for nuclear monitoring, Does not rely on individualized signal detection thresholds - it's the network solution that matters.

Have recent earthquakes exposed flaws in or misunderstandings of probabilistic seismic hazard analysis?

USGS Publications Warehouse

Hanks, Thomas C.; Beroza, Gregory C.; Toda, Shinji

2012-01-01

In a recent Opinion piece in these pages, Stein et al. (2011) offer a remarkable indictment of the methods, models, and results of probabilistic seismic hazard analysis (PSHA). The principal object of their concern is the PSHA map for Japan released by the Japan Headquarters for Earthquake Research Promotion (HERP), which is reproduced by Stein et al. (2011) as their Figure 1 and also here as our Figure 1. It shows the probability of exceedance (also referred to as the “hazard”) of the Japan Meteorological Agency (JMA) intensity 6–lower (JMA 6–) in Japan for the 30-year period beginning in January 2010. JMA 6– is an earthquake-damage intensity measure that is associated with fairly strong ground motion that can be damaging to well-built structures and is potentially destructive to poor construction (HERP, 2005, appendix 5). Reiterating Geller (2011, p. 408), Stein et al. (2011, p. 623) have this to say about Figure 1: The regions assessed as most dangerous are the zones of three hypothetical “scenario earthquakes” (Tokai, Tonankai, and Nankai; see map). However, since 1979, earthquakes that caused 10 or more fatalities in Japan actually occurred in places assigned a relatively low probability. This discrepancy—the latest in a string of negative results for the characteristic model and its cousin the seismic-gap model—strongly suggest that the hazard map and the methods used to produce it are flawed and should be discarded. Given the central role that PSHA now plays in seismic risk analysis, performance-based engineering, and design-basis ground motions, discarding PSHA would have important consequences. We are not persuaded by the arguments of Geller (2011) and Stein et al. (2011) for doing so because important misunderstandings about PSHA seem to have conditioned them. In the quotation above, for example, they have confused important differences between earthquake-occurrence observations and ground-motion hazard calculations.

Lunar Seismology

ERIC Educational Resources Information Center

Latham, Gary V.

1973-01-01

Summarizes major findings from the passive seismic experiment on the Moon with the Apollo seismic network illustrated in a map. Concludes that human beings may have discovered something very basic about the physics of planetary interiors because of the affirmation of the presence of a warm'' lunar interior. (CC)

Seismic hazard maps for Haiti

USGS Publications Warehouse

Frankel, Arthur; Harmsen, Stephen; Mueller, Charles; Calais, Eric; Haase, Jennifer

2011-01-01

We have produced probabilistic seismic hazard maps of Haiti for peak ground acceleration and response spectral accelerations that include the hazard from the major crustal faults, subduction zones, and background earthquakes. The hazard from the Enriquillo-Plantain Garden, Septentrional, and Matheux-Neiba fault zones was estimated using fault slip rates determined from GPS measurements. The hazard from the subduction zones along the northern and southeastern coasts of Hispaniola was calculated from slip rates derived from GPS data and the overall plate motion. Hazard maps were made for a firm-rock site condition and for a grid of shallow shear-wave velocities estimated from topographic slope. The maps show substantial hazard throughout Haiti, with the highest hazard in Haiti along the Enriquillo-Plantain Garden and Septentrional fault zones. The Matheux-Neiba Fault exhibits high hazard in the maps for 2% probability of exceedance in 50 years, although its slip rate is poorly constrained.

A Geophysical Atlas for Interpretation of Satellite-derived Data

NASA Technical Reports Server (NTRS)

Lowman, P. D., Jr. (Editor); Frey, H. V. (Editor); Davis, W. M.; Greenberg, A. P.; Hutchinson, M. K.; Langel, R. A.; Lowrey, B. E.; Marsh, J. G.; Mead, G. D.; Okeefe, J. A.

1979-01-01

A compilation of maps of global geophysical and geological data plotted on a common scale and projection is presented. The maps include satellite gravity, magnetic, seismic, volcanic, tectonic activity, and mantle velocity anomaly data. The Bibliographic references for all maps are included.

Seismic imaging of the Sun's far hemisphere and its applications in space weather forecasting

NASA Astrophysics Data System (ADS)

Lindsey, Charles; Braun, Douglas

2017-06-01

The interior of the Sun is filled acoustic waves with periods of about 5 min. These waves, called "p modes," are understood to be excited by convection in a thin layer beneath the Sun's surface. The p modes cause seismic ripples, which we call "the solar oscillations." Helioseismic observatories use Doppler observations to map these oscillations, both spatially and temporally. The p modes propagate freely throughout the solar interior, reverberating between the near and far hemispheres. They also interact strongly with active regions at the surfaces of both hemispheres, carrying the signatures of said interactions with them. Computational analysis of the solar oscillations mapped in the Sun's near hemisphere, applying basic principles of wave optics to model the implied p modes propagating through the solar interior, gives us seismic maps of large active regions in the Sun's far hemisphere. These seismic maps are useful for space weather forecasting. For the past decade, NASA's twin STEREO spacecraft have given us full coverage of the Sun's far hemisphere in electromagnetic (EUV) radiation from the far side of Earth's orbit about the Sun. We are now approaching a decade during which the STEREO spacecraft will lose their farside vantage. There will occur significant periods from thence during which electromagnetic coverage of the Sun's far hemisphere will be incomplete or nil. Solar seismology will make it possible to continue our monitor of large active regions in the Sun's far hemisphere for the needs of space weather forecasters during these otherwise blind periods.

Seismic imaging of the Sun's far hemisphere and its applications in space weather forecasting.

PubMed

Lindsey, Charles; Braun, Douglas

2017-06-01

The interior of the Sun is filled acoustic waves with periods of about 5 min. These waves, called " p modes," are understood to be excited by convection in a thin layer beneath the Sun's surface. The p modes cause seismic ripples, which we call "the solar oscillations." Helioseismic observatories use Doppler observations to map these oscillations, both spatially and temporally. The p modes propagate freely throughout the solar interior, reverberating between the near and far hemispheres. They also interact strongly with active regions at the surfaces of both hemispheres, carrying the signatures of said interactions with them. Computational analysis of the solar oscillations mapped in the Sun's near hemisphere, applying basic principles of wave optics to model the implied p modes propagating through the solar interior, gives us seismic maps of large active regions in the Sun's far hemisphere. These seismic maps are useful for space weather forecasting. For the past decade, NASA's twin STEREO spacecraft have given us full coverage of the Sun's far hemisphere in electromagnetic (EUV) radiation from the far side of Earth's orbit about the Sun. We are now approaching a decade during which the STEREO spacecraft will lose their farside vantage. There will occur significant periods from thence during which electromagnetic coverage of the Sun's far hemisphere will be incomplete or nil. Solar seismology will make it possible to continue our monitor of large active regions in the Sun's far hemisphere for the needs of space weather forecasters during these otherwise blind periods.

Mapping debris flow susceptibility using analytical network process in Kodaikkanal Hills, Tamil Nadu (India)

NASA Astrophysics Data System (ADS)

Sujatha, Evangelin Ramani; Sridhar, Venkataramana

2017-12-01

Rapid debris flows, a mixture of unconsolidated sediments and water travelling at speeds > 10 m/s are the most destructive water related mass movements that affect hill and mountain regions. The predisposing factors setting the stage for the event are the availability of materials, type of materials, stream power, slope gradient, aspect and curvature, lithology, land use and land cover, lineament density, and drainage. Rainfall is the most common triggering factor that causes debris flow in the Palar subwatershed and seismicity is not considered as it is a stable continental region and moderate seismic zone. Also, there are no records of major seismic activities in the past. In this study, one of the less explored heuristic methods known as the analytical network process (ANP) is used to map the spatial propensity of debris flow. This method is based on top-down decision model and is a multi-criteria, decision-making tool that translates subjective assessment of relative importance to weights or scores and is implemented in the Palar subwatershed which is part of the Western Ghats in southern India. The results suggest that the factors influencing debris flow susceptibility in this region are the availability of material on the slope, peak flow, gradient of the slope, land use and land cover, and proximity to streams. Among all, peak discharge is identified as the chief factor causing debris flow. The use of micro-scale watersheds demonstrated in this study to develop the susceptibility map can be very effective for local level planning and land management.

Predictive habitat modelling of humpback (Megaptera novaeangliae) and Antarctic minke (Balaenoptera bonaerensis) whales in the Southern Ocean as a planning tool for seismic surveys

NASA Astrophysics Data System (ADS)

Bombosch, Annette; Zitterbart, Daniel P.; Van Opzeeland, Ilse; Frickenhaus, Stephan; Burkhardt, Elke; Wisz, Mary S.; Boebel, Olaf

2014-09-01

Seismic surveys are frequently a matter of concern regarding their potentially negative impacts on marine mammals. In the Southern Ocean, which provides a critical habitat for several endangered cetacean species, seismic research activities are undertaken at a circumpolar scale. In order to minimize impacts of these surveys, pre-cruise planning requires detailed, spatio-temporally resolved knowledge on the likelihood of encountering these species in the survey area. In this publication we present predictive habitat modelling as a potential tool to support decisions for survey planning. We associated opportunistic sightings (2005-2011) of humpback (Megaptera novaeangliae, N=93) and Antarctic minke whales (Balaenoptera bonaerensis, N=139) with a range of static and dynamic environmental variables. A maximum entropy algorithm (Maxent) was used to develop habitat models and to calculate daily basinwide/circumpolar prediction maps to evaluate how species-specific habitat conditions evolved throughout the spring and summer months. For both species, prediction maps revealed considerable changes in habitat suitability throughout the season. Suitable humpback whale habitat occurred predominantly in ice-free areas, expanding southwards with the retreating sea ice edge, whereas suitable Antarctic minke whale habitat was consistently predicted within sea ice covered areas. Daily, large-scale prediction maps provide a valuable tool to design layout and timing of seismic surveys as they allow the identification and consideration of potential spatio-temporal hotspots to minimize potential impacts of seismic surveys on Antarctic cetacean species.

Sediment Volume Record of Paleogene-Neogene Transantarctic Mountains Erosion and Landscape Modification, McMurdo Sound Region, Antarctica

NASA Astrophysics Data System (ADS)

Hall, T.; Wilson, T. J.; Henrys, S.; Speece, M. A.

2016-12-01

The interplay of tectonics and climate is recorded in the sedimentary strata within Victoria Land Basin, McMurdo Sound, Antarctica. Patterns of Cenozoic sedimentation are documented from interpretation of seismic reflection profiles calibrated by drillhole data in McMurdo Sound, and these patterns provide enhanced constraints on the evolution of the coupled Transantarctic Mountains-West Antarctic Rift System and on ice sheet advance/retreat through multiple climate cycles. The research focuses on shifts from warm based to cold based ice sheets through the variable climate and ice sheet conditions that characterized the early to middle Miocene. The study seeks to test the view that cold based ice sheets in arid, polar deserts minimally erode the landscape by calculating sediment volumes for critical climatic intervals. Revised seismic mapping through McMurdo Sound has been completed, utilizing the seismic stratigraphic framework first established by Fielding et al. (2006) and new reflectors marking unconformities identified from the AND-2A core (Levy et al., 2016). Reflector age constraints are derived by tying surfaces to the Cape Roberts Project, CIROS-1, and AND-2A drillholes. Seismic facies coupled with AND-2A core provenance information provides insight into depositional mechanisms and ice sheet behavior. Seismic facies transitions occur across the major unconformity surfaces in the AND-2A core. Sediment volume calculations for subareas within McMurdo Sound where reflectors are most continuous indicate substantial decreases in preserved sediment volume between the Oligocene and Early Miocene sequences, and between the early and mid-Miocene sequences. Sediment volumes, used in combination with an ice sheet model in a backstacking procedure, provide constraints on landscape modification and further understanding of how landscapes erode under warm and cold based ice sheet regimes.

Preliminary atlas of active shallow tectonic deformation in the Puget Lowland, Washington

USGS Publications Warehouse

Barnett, Elizabeth A.; Haugerud, Ralph A.; Sherrod, Brian L.; Weaver, Craig S.; Pratt, Thomas L.; Blakely, Richard J.

2010-01-01

This atlas presents an up-to-date map compilation of the geological and geophysical observations that underpin interpretations of active, surface-deforming faults in the Puget Lowland, Washington. Shallow lowland faults are mapped where observations of deformation from paleoseismic, seismic-reflection, and potential-field investigations converge. Together, results from these studies strengthen the identification and characterization of regional faults and show that as many as a dozen shallow faults have been active during the Holocene. The suite of maps presented in our atlas identifies sites that have evidence of deformation attributed to these shallow faults. For example, the paleoseismic-investigations map shows where coseismic surface rupture and deformation produced geomorphic scarps and deformed shorelines. Other maps compile results of seismic-reflection and potential-field studies that demonstrate evidence of deformation along suspected fault structures in the subsurface. Summary maps show the fault traces derived from, and draped over, the datasets presented in the preceding maps. Overall, the atlas provides map users with a visual overview of the observations and interpretations that support the existence of active, shallow faults beneath the densely populated Puget Lowland.

Quantifying uncertainty in NDSHA estimates due to earthquake catalogue

NASA Astrophysics Data System (ADS)

Magrin, Andrea; Peresan, Antonella; Vaccari, Franco; Panza, Giuliano

2014-05-01

The procedure for the neo-deterministic seismic zoning, NDSHA, is based on the calculation of synthetic seismograms by the modal summation technique. This approach makes use of information about the space distribution of large magnitude earthquakes, which can be defined based on seismic history and seismotectonics, as well as incorporating information from a wide set of geological and geophysical data (e.g., morphostructural features and ongoing deformation processes identified by earth observations). Hence the method does not make use of attenuation models (GMPE), which may be unable to account for the complexity of the product between seismic source tensor and medium Green function and are often poorly constrained by the available observations. NDSHA defines the hazard from the envelope of the values of ground motion parameters determined considering a wide set of scenario earthquakes; accordingly, the simplest outcome of this method is a map where the maximum of a given seismic parameter is associated to each site. In NDSHA uncertainties are not statistically treated as in PSHA, where aleatory uncertainty is traditionally handled with probability density functions (e.g., for magnitude and distance random variables) and epistemic uncertainty is considered by applying logic trees that allow the use of alternative models and alternative parameter values of each model, but the treatment of uncertainties is performed by sensitivity analyses for key modelling parameters. To fix the uncertainty related to a particular input parameter is an important component of the procedure. The input parameters must account for the uncertainty in the prediction of fault radiation and in the use of Green functions for a given medium. A key parameter is the magnitude of sources used in the simulation that is based on catalogue informations, seismogenic zones and seismogenic nodes. Because the largest part of the existing catalogues is based on macroseismic intensity, a rough estimate of ground motion error can therefore be the factor of 2, intrinsic in MCS scale. We tested this hypothesis by the analysis of uncertainty in ground motion maps due to the catalogue random errors in magnitude and localization.

ShakeMap Atlas 2.0: an improved suite of recent historical earthquake ShakeMaps for global hazard analyses and loss model calibration

USGS Publications Warehouse

Garcia, D.; Mah, R.T.; Johnson, K.L.; Hearne, M.G.; Marano, K.D.; Lin, K.-W.; Wald, D.J.

2012-01-01

We introduce the second version of the U.S. Geological Survey ShakeMap Atlas, which is an openly-available compilation of nearly 8,000 ShakeMaps of the most significant global earthquakes between 1973 and 2011. This revision of the Atlas includes: (1) a new version of the ShakeMap software that improves data usage and uncertainty estimations; (2) an updated earthquake source catalogue that includes regional locations and finite fault models; (3) a refined strategy to select prediction and conversion equations based on a new seismotectonic regionalization scheme; and (4) vastly more macroseismic intensity and ground-motion data from regional agencies All these changes make the new Atlas a self-consistent, calibrated ShakeMap catalogue that constitutes an invaluable resource for investigating near-source strong ground-motion, as well as for seismic hazard, scenario, risk, and loss-model development. To this end, the Atlas will provide a hazard base layer for PAGER loss calibration and for the Earthquake Consequences Database within the Global Earthquake Model initiative.

Fractal interrelationships in field and seismic data. Quarterly report, September 21 - December 31, 1995

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

Wilson, T.H.; Dominic, J.; Halverson, J.

1995-12-31

Under task 1 contour irregularities traced over both study areas in the previous quarter were scanned into the computer and digitized at a 30 meter interval. Patters mapped in both the Granny Creek and Middle Mountain field areas are presented in Figures 1 and 2 respectively. One of the hypotheses of this research project is that contour irregularities must be controlled by a combination of sedimentation features, lithologic variation, and local structure and fracture distribution. The most promising result obtained thus far in this study are those reported under Tasks 4 and 5, seismic analysis. If further tests continue tomore » support the observation that increased fractal dimension reflects the presence of detached structure, the analytical techniques employed here may be of use in the routine evaluation of seismic data to locate subtle traps. The observations may allow one to predict the variation of fractal dimension within a subsurface fracture network based on seismic observation of resolvable structural parameters. Such predictions would provide a working hypothesis, which could be modified within the context of available subsurface data.« less

Quantification of sand fraction from seismic attributes using Neuro-Fuzzy approach

NASA Astrophysics Data System (ADS)

Verma, Akhilesh K.; Chaki, Soumi; Routray, Aurobinda; Mohanty, William K.; Jenamani, Mamata

2014-12-01

In this paper, we illustrate the modeling of a reservoir property (sand fraction) from seismic attributes namely seismic impedance, seismic amplitude, and instantaneous frequency using Neuro-Fuzzy (NF) approach. Input dataset includes 3D post-stacked seismic attributes and six well logs acquired from a hydrocarbon field located in the western coast of India. Presence of thin sand and shale layers in the basin area makes the modeling of reservoir characteristic a challenging task. Though seismic data is helpful in extrapolation of reservoir properties away from boreholes; yet, it could be challenging to delineate thin sand and shale reservoirs using seismic data due to its limited resolvability. Therefore, it is important to develop state-of-art intelligent methods for calibrating a nonlinear mapping between seismic data and target reservoir variables. Neural networks have shown its potential to model such nonlinear mappings; however, uncertainties associated with the model and datasets are still a concern. Hence, introduction of Fuzzy Logic (FL) is beneficial for handling these uncertainties. More specifically, hybrid variants of Artificial Neural Network (ANN) and fuzzy logic, i.e., NF methods, are capable for the modeling reservoir characteristics by integrating the explicit knowledge representation power of FL with the learning ability of neural networks. In this paper, we opt for ANN and three different categories of Adaptive Neuro-Fuzzy Inference System (ANFIS) based on clustering of the available datasets. A comparative analysis of these three different NF models (i.e., Sugeno-type fuzzy inference systems using a grid partition on the data (Model 1), using subtractive clustering (Model 2), and using Fuzzy c-means (FCM) clustering (Model 3)) and ANN suggests that Model 3 has outperformed its counterparts in terms of performance evaluators on the present dataset. Performance of the selected algorithms is evaluated in terms of correlation coefficients (CC), root mean square error (RMSE), absolute error mean (AEM) and scatter index (SI) between target and predicted sand fraction values. The achieved estimation accuracy may diverge minutely depending on geological characteristics of a particular study area. The documented results in this study demonstrate acceptable resemblance between target and predicted variables, and hence, encourage the application of integrated machine learning approaches such as Neuro-Fuzzy in reservoir characterization domain. Furthermore, visualization of the variation of sand probability in the study area would assist in identifying placement of potential wells for future drilling operations.

The improved broadband Real-Time Seismic Network in Romania

NASA Astrophysics Data System (ADS)

Neagoe, C.; Ionescu, C.

2009-04-01

Starting with 2002 the National Institute for Earth Physics (NIEP) has developed its real-time digital seismic network. This network consists of 96 seismic stations of which 48 broad band and short period stations and two seismic arrays are transmitted in real-time. The real time seismic stations are equipped with Quanterra Q330 and K2 digitizers, broadband seismometers (STS2, CMG40T, CMG 3ESP, CMG3T) and strong motions sensors Kinemetrics episensors (+/- 2g). SeedLink and AntelopeTM (installed on MARMOT) program packages are used for real-time (RT) data acquisition and exchange. The communication from digital seismic stations to the National Data Center in Bucharest is assured by 5 providers (GPRS, VPN, satellite communication, radio lease line and internet), which will assure the back-up communications lines. The processing centre runs BRTT's AntelopeTM 4.10 data acquisition and processing software on 2 workstations for real-time processing and post processing. The Antelope Real-Time System is also providing automatic event detection, arrival picking, event location and magnitude calculation. It provides graphical display and reporting within near-real-time after a local or regional event occurred. Also at the data center was implemented a system to collect macroseismic information using the internet on which macro seismic intensity maps are generated. In the near future at the data center will be install Seiscomp 3 data acquisition processing software on a workstation. The software will run in parallel with Antelope software as a back-up. The present network will be expanded in the near future. In the first half of 2009 NIEP will install 8 additional broad band stations in Romanian territory, which also will be transmitted to the data center in real time. The Romanian Seismic Network is permanently exchanging real -time waveform data with IRIS, ORFEUS and different European countries through internet. In Romania, magnitude and location of an earthquake are now available within a few minutes after the earthquake occurred. One of the greatest challenges in the near future is to provide shaking intensity maps and other ground motion parameters, within 5 minutes post-event, on the Internet and GIS-based format in order to improve emergency response, public information, preparedness and hazard mitigation

Probabilistic Tsunami Hazard Analysis

NASA Astrophysics Data System (ADS)

Thio, H. K.; Ichinose, G. A.; Somerville, P. G.; Polet, J.

2006-12-01

The recent tsunami disaster caused by the 2004 Sumatra-Andaman earthquake has focused our attention to the hazard posed by large earthquakes that occur under water, in particular subduction zone earthquakes, and the tsunamis that they generate. Even though these kinds of events are rare, the very large loss of life and material destruction caused by this earthquake warrant a significant effort towards the mitigation of the tsunami hazard. For ground motion hazard, Probabilistic Seismic Hazard Analysis (PSHA) has become a standard practice in the evaluation and mitigation of seismic hazard to populations in particular with respect to structures, infrastructure and lifelines. Its ability to condense the complexities and variability of seismic activity into a manageable set of parameters greatly facilitates the design of effective seismic resistant buildings but also the planning of infrastructure projects. Probabilistic Tsunami Hazard Analysis (PTHA) achieves the same goal for hazards posed by tsunami. There are great advantages of implementing such a method to evaluate the total risk (seismic and tsunami) to coastal communities. The method that we have developed is based on the traditional PSHA and therefore completely consistent with standard seismic practice. Because of the strong dependence of tsunami wave heights on bathymetry, we use a full waveform tsunami waveform computation in lieu of attenuation relations that are common in PSHA. By pre-computing and storing the tsunami waveforms at points along the coast generated for sets of subfaults that comprise larger earthquake faults, we can efficiently synthesize tsunami waveforms for any slip distribution on those faults by summing the individual subfault tsunami waveforms (weighted by their slip). This efficiency make it feasible to use Green's function summation in lieu of attenuation relations to provide very accurate estimates of tsunami height for probabilistic calculations, where one typically computes thousands of earthquake scenarios. We have carried out preliminary tsunami hazard calculations for different return periods for western North America and Hawaii based on thousands of earthquake scenarios around the Pacific rim and along the coast of North America. We will present tsunami hazard maps for several return periods and also discuss how to use these results for probabilistic inundation and runup mapping. Our knowledge of certain types of tsunami sources is very limited (e.g. submarine landslides), but a probabilistic framework for tsunami hazard evaluation can include even such sources and their uncertainties and present the overall hazard in a meaningful and consistent way.

Vulnerability and seismic damage scenarios for Barcelona (Spain) by using GIS

NASA Astrophysics Data System (ADS)

Lantada, N.; Pujades, L. G.; Barbat, A.

2003-04-01

An integrated GIS-based analysis (using ArcView GIS) is performed in order to estimate damage scenarios for VI, VII and VIII EMS-98 seismic intensities in Barcelona (Spain). The analysis of vulnerability and damage of individual buildings is performed according to a simplified method developed by Giovanazzi and Lagomarsino at the University of Genoa (Italy). An index of average vulnerability is associated to each building typology, which may be refined on the basis of behaviour modifiers. The index allows identification of an analytical relationship between seismic input (intensity) and damage, described by a binomial distribution. This methodology, which is based on the EMS-98 building typologies and preserves the compatibility with preceding methods, is applied to the two main residential building typologies of Barcelona, that is, unreinforced masonry and reinforced concrete buildings. Then, the specific residential buildings of Barcelona are classified in different groups characterized by a similar seismic behaviour. Therefore, all buildings belonging to each typology are cast in the most probable class according to vulnerability. In this way, the average vulnerability index is associated to each building typology of Barcelona and it is refined later on the basis of behaviour modifiers, linked to the number of stories, the year of construction and their state of maintenance. The ability of GIS tools to store, manage, analyse, and display the large amount of spatial and tabular data involved in this study allows to map average vulnerability indexes, and damage for the entire city. That is, vulnerability and damage scenarios. The obtained results show a high vulnerability and high expected seismic damage. For a VI degree of intensity, the maximum expected damage is in the range 15-30 % in the oldest zones of the city, the downtown, while for intensity VII it is in the range 45-60%. The developed GIS tool involves a friendly interface that allows new models and database information to be included in the same framework. As a new step to the seismic risk assessment, and in addition to the building characteristics, the destination of the building, as well as the essential buildings, and the density of population for census zones, have been included in the GIS database. Combining this information with the previous damage maps we will be able to obtain more complete damage scenarios including, deaths, injuries, and homeless.

Seismic hazard and risks based on the Unified Scaling Law for Earthquakes

NASA Astrophysics Data System (ADS)

Kossobokov, Vladimir; Nekrasova, Anastasia

2014-05-01

Losses from natural disasters continue to increase mainly due to poor understanding by majority of scientific community, decision makers and public, the three components of Risk, i.e., Hazard, Exposure, and Vulnerability. Contemporary Science is responsible for not coping with challenging changes of Exposures and their Vulnerability inflicted by growing population, its concentration, etc., which result in a steady increase of Losses from Natural Hazards. Scientists owe to Society for lack of knowledge, education, and communication. In fact, Contemporary Science can do a better job in disclosing Natural Hazards, assessing Risks, and delivering such knowledge in advance catastrophic events. Any kind of risk estimates R(g) at location g results from a convolution of the natural hazard H(g) with the exposed object under consideration O(g) along with its vulnerability V(O(g)). Note that g could be a point, or a line, or a cell on or under the Earth surface and that distribution of hazards, as well as objects of concern and their vulnerability, could be time-dependent. There exist many different risk estimates even if the same object of risk and the same hazard are involved. It may result from the different laws of convolution, as well as from different kinds of vulnerability of an object of risk under specific environments and conditions. Both conceptual issues must be resolved in a multidisciplinary problem oriented research performed by specialists in the fields of hazard, objects of risk, and object vulnerability, i.e. specialists in earthquake engineering, social sciences and economics. To illustrate this general concept, we first construct seismic hazard assessment maps based on the Unified Scaling Law for Earthquakes (USLE). The parameters A, B, and C of USLE, i.e. log N(M,L) = A - B•(M-6) + C•log L, where N(M,L) is the expected annual number of earthquakes of a certain magnitude M within an area of linear size L, are used to estimate the expected maximum magnitude in 50 years and the corresponding expected ground shaking intensity in a cell g of a uniform grid of the region of interest. Then such a seismic hazard map is used to generate earthquake risk maps based on the exposed population density. Some oversimplified convolutions R(g) = H(g)•gP•F(gP) of seismic hazard assessment maps H(g) are applied in a few regions with population density distribution P of vulnerability V=F(gP), where g is a cell of a uniform grid and gP is the integral of the population density over the cell g.

The character and amplitude of ‘discontinuous’ bottom-simulating reflections in marine seismic data

DOE PAGES

Hillman, Jess I. T.; Cook, Ann E.; Sawyer, Derek E.; ...

2016-11-22

Bottom-simulating reflections (BSRs) identified in seismic data are well documented; and are commonly interpreted to indicate the presence of gas hydrates along continental margins, as well as to estimate regional volumes of gas hydrate. A BSR is defined as a reflection that sub-parallels the seafloor but is opposite in polarity and cross-cuts dipping sedimentary strata. BSRs form as a result of a strong negative acoustic impedance contrast. BSRs, however, are a diverse seismic phenomena that manifest in strikingly contrasting ways in different geological settings, and in different seismic data types. We investigate the characteristics of BSRs, using conventional and highmore » resolution, 2D and 3D seismic data sets in three locations: the Terrebonne and Orca Basins in the Gulf of Mexico, and Blake Ridge on the US Atlantic Margin. The acquisition geometry and frequency content of the seismic data significantly impact the resultant character of BSRs, as observed with depth and amplitude maps of the BSRs. Furthermore, our amplitude maps reinforce the concept that the BSR represents a zone, over which the transition from hydrate to free gas occurs, as opposed to the conventional model of the BSR occurring at a single interface. Our results show that a BSR can be mapped in three dimensions but it is not spatially continuous, at least not at the basin scale. Rather, a BSR manifests itself as a discontinuous, or patchy, reflection and only at local scales is it continuous. We suggest the discontinuous nature of BSRs is the result of variable saturation and distribution of free gas and hydrate, acquisition geometry and frequency content of the recorded seismic data. Lastly, the commonly accepted definition of a BSR should be broadened with careful consideration of these factors, to represent the uppermost extent of enhanced amplitude at the shallowest occurrence of free gas trapped by overlying hydrate-bearing sediments.« less

The character and amplitude of 'discontinuous' bottom-simulating reflections in marine seismic data

NASA Astrophysics Data System (ADS)

Hillman, Jess I. T.; Cook, Ann E.; Sawyer, Derek E.; Küçük, H. Mert; Goldberg, David S.

2017-02-01

Bottom-simulating reflections (BSRs) identified in seismic data are well documented; and are commonly interpreted to indicate the presence of gas hydrates along continental margins, as well as to estimate regional volumes of gas hydrate. A BSR is defined as a reflection that sub-parallels the seafloor but is opposite in polarity and cross-cuts dipping sedimentary strata. BSRs form as a result of a strong negative acoustic impedance contrast. BSRs, however, are a diverse seismic phenomena that manifest in strikingly contrasting ways in different geological settings, and in different seismic data types. We investigate the characteristics of BSRs, using conventional and high resolution, 2D and 3D seismic data sets in three locations: the Terrebonne and Orca Basins in the Gulf of Mexico, and Blake Ridge on the US Atlantic Margin. The acquisition geometry and frequency content of the seismic data significantly impact the resultant character of BSRs, as observed with depth and amplitude maps of the BSRs. Furthermore, our amplitude maps reinforce the concept that the BSR represents a zone, over which the transition from hydrate to free gas occurs, as opposed to the conventional model of the BSR occurring at a single interface. Our results show that a BSR can be mapped in three dimensions but it is not spatially continuous, at least not at the basin scale. Rather, a BSR manifests itself as a discontinuous, or patchy, reflection and only at local scales is it continuous. We suggest the discontinuous nature of BSRs is the result of variable saturation and distribution of free gas and hydrate, acquisition geometry and frequency content of the recorded seismic data. The commonly accepted definition of a BSR should be broadened with careful consideration of these factors, to represent the uppermost extent of enhanced amplitude at the shallowest occurrence of free gas trapped by overlying hydrate-bearing sediments.

The character and amplitude of ‘discontinuous’ bottom-simulating reflections in marine seismic data

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

Hillman, Jess I. T.; Cook, Ann E.; Sawyer, Derek E.

Bottom-simulating reflections (BSRs) identified in seismic data are well documented; and are commonly interpreted to indicate the presence of gas hydrates along continental margins, as well as to estimate regional volumes of gas hydrate. A BSR is defined as a reflection that sub-parallels the seafloor but is opposite in polarity and cross-cuts dipping sedimentary strata. BSRs form as a result of a strong negative acoustic impedance contrast. BSRs, however, are a diverse seismic phenomena that manifest in strikingly contrasting ways in different geological settings, and in different seismic data types. We investigate the characteristics of BSRs, using conventional and highmore » resolution, 2D and 3D seismic data sets in three locations: the Terrebonne and Orca Basins in the Gulf of Mexico, and Blake Ridge on the US Atlantic Margin. The acquisition geometry and frequency content of the seismic data significantly impact the resultant character of BSRs, as observed with depth and amplitude maps of the BSRs. Furthermore, our amplitude maps reinforce the concept that the BSR represents a zone, over which the transition from hydrate to free gas occurs, as opposed to the conventional model of the BSR occurring at a single interface. Our results show that a BSR can be mapped in three dimensions but it is not spatially continuous, at least not at the basin scale. Rather, a BSR manifests itself as a discontinuous, or patchy, reflection and only at local scales is it continuous. We suggest the discontinuous nature of BSRs is the result of variable saturation and distribution of free gas and hydrate, acquisition geometry and frequency content of the recorded seismic data. Lastly, the commonly accepted definition of a BSR should be broadened with careful consideration of these factors, to represent the uppermost extent of enhanced amplitude at the shallowest occurrence of free gas trapped by overlying hydrate-bearing sediments.« less

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

Grillot, L.R.; Anderton, P.W.; Haselton, T.M.

The Espoir oil field, located approximately 13 km offshore Ivory Coast, was discovered in 1980 by a joint venture comprised of Phillips Petroleum Company, AGIP, SEDCO Energy, and PETROCI. Following the discovery, a three-dimensional seismic survey was recorded by GSI in 1981-1982 to provide detailed seismic coverage of Espoir field and adjacent features. The seismic program consisted of 7700 line-km of data acquired in a single survey area that is located on the edge of the continental shelf and extends into deep water. In comparison with previous two-dimensional seismic surveys, the three-dimensional data provided several improvements in interpretation and mappingmore » including: (1) sharper definition of structural features, (2) reliable correlations of horizons and fault traces between closely spaced tracks, (3) detailed time contour maps from time-slice sections, and (4) improved velocity model for depth conversion. The improved mapping helped us identify additional well locations; the results of these wells compared favorably with the interpretation made prior to drilling.« less

Installation restoration research program: Assessment of geophysical methods for subsurface geologic mapping, cluster 13, Edgewood Area, Aberdeen Proving Ground, Maryland. Final report

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

Butler, D.K.; Sharp, M.K.; Sjostrom, K.J.

1996-10-01

Seismic refraction, electrical resistivity, and transient electromagnetic surveys were conducted at a portion of Cluster 13, Edgewood Area of Aberdeen Proving Ground, Maryland. Seismic refraction cross sections map the topsoil layer and the water table (saturated zone). The water table elevations from the seismic surveys correlate closely with water table elevations in nearby monitoring wells. Electrical resistivity cross sections reveal a very complicated distribution of sandy and clayey facies in the upper 10 - 15 m of the subsurface. A continuous surficial (topsoil) layer correlates with the surficial layer of the seismic section and nearby boring logs. The complexity andmore » details of the electrical resistivity cross section correlate well with boring and geophysical logs from nearby wells. The transient electromagnetic surveys map the Pleistocene-Cretaceous boundary, the saprolite, and the top of the Precambrian crystalline rocks. Conducting the transient electromagnetic surveys on a grid pattern allows the construction of a three-dimensional representation of subsurface geology (as represented by variations of electrical resistivity). Thickness and depth of the saprolitic layer and depth to top of the Precambrian rocks are consistent with generalized geologic cross sections for the Edgewood Area and depths projected from reported depths at the Aberdeen Proving Ground NW boundary using regional dips.« less

Integration of seismic and petrophysics to characterize reservoirs in "ALA" oil field, Niger Delta.

PubMed

Alao, P A; Olabode, S O; Opeloye, S A

2013-01-01

In the exploration and production business, by far the largest component of geophysical spending is driven by the need to characterize (potential) reservoirs. The simple reason is that better reservoir characterization means higher success rates and fewer wells for reservoir exploitation. In this research work, seismic and well log data were integrated in characterizing the reservoirs on "ALA" field in Niger Delta. Three-dimensional seismic data was used to identify the faults and map the horizons. Petrophysical parameters and time-depth structure maps were obtained. Seismic attributes was also employed in characterizing the reservoirs. Seven hydrocarbon-bearing reservoirs with thickness ranging from 9.9 to 71.6 m were delineated. Structural maps of horizons in six wells containing hydrocarbon-bearing zones with tops and bottoms at range of -2,453 to -3,950 m were generated; this portrayed the trapping mechanism to be mainly fault-assisted anticlinal closures. The identified prospective zones have good porosity, permeability, and hydrocarbon saturation. The environments of deposition were identified from log shapes which indicate a transitional-to-deltaic depositional environment. In this research work, new prospects have been recommended for drilling and further research work. Geochemical and biostratigraphic studies should be done to better characterize the reservoirs and reliably interpret the depositional environments.

LiDAR-Assisted identification of an active fault near Truckee, California

USGS Publications Warehouse

Hunter, L.E.; Howle, J.F.; Rose, R.S.; Bawden, G.W.

2011-01-01

We use high-resolution (1.5-2.4 points/m2) bare-earth airborne Light Detection and Ranging (LiDAR) imagery to identify, map, constrain, and visualize fault-related geomorphology in densely vegetated terrain surrounding Martis Creek Dam near Truckee, California. Bare-earth LiDAR imagery reveals a previously unrecognized and apparently youthful right-lateral strike-slip fault that exhibits laterally continuous tectonic geomorphic features over a 35-km-long zone. If these interpretations are correct, the fault, herein named the Polaris fault, may represent a significant seismic hazard to the greater Truckee-Lake Tahoe and Reno-Carson City regions. Three-dimensional modeling of an offset late Quaternary terrace riser indicates a minimum tectonic slip rate of 0.4 ?? 0.1 mm/yr.Mapped fault patterns are fairly typical of regional patterns elsewhere in the northern Walker Lane and are in strong coherence with moderate magnitude historical seismicity of the immediate area, as well as the current regional stress regime. Based on a range of surface-rupture lengths and depths to the base of the seismogenic zone, we estimate a maximum earthquake magnitude (M) for the Polaris fault to be between 6.4 and 6.9.

InSight Final Flight Installation of Heatshield

NASA Image and Video Library

2018-04-12

In the Astrotech facility at Vandenberg Air Force Base in California, technicians and engineers place the heatshield on NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander prior to encapsulation in its payload fairing. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

Liftoff of InSight

NASA Image and Video Library

2018-05-05

A United Launch Alliance Atlas V rocket lifts off at 4:05 a.m. PDT (7:05 a.m. EDT) from Space Launch Complex 3 at Vandenberg Air Force Base in California carrying NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created.

InSight Liftoff

NASA Image and Video Library

2018-05-05

A United Launch Alliance Atlas V rocket lifts off from Space Launch Complex 3 at Vandenberg Air Force Base, California, carrying NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander. Liftoff was at 4:05 a.m. PDT (7:05 a.m. EDT). The spacecraft will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander is positioned atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Liftoff

NASA Image and Video Library

2018-05-05

A United Launch Alliance Atlas V rocket lifts off from Space Launch Complex 3 at Vandenberg Air Force Base, California, carrying NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander. Liftoff was at 4:05 a.m. PDT (7:05 a.m. EDT). The spacecraft will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created.

InSight Lift & Mate

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, technicians and engineers position NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, technicians and engineers position NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander has been mated atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

At Space l Launch Complex 3 at Vandenberg Air Force Base in California, a crane is used to lift NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander for mating atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Rollout to Pad

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, a crane is used to lift NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander for mating atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Lift & Mate

NASA Image and Video Library

2018-04-23

At Space Launch Complex 3 at Vandenberg Air Force Base in California, a crane is used to lift NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander for mating atop a United Launch Alliance Atlas V rocket. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

InSight Battery Installation

NASA Image and Video Library

2018-04-20

In the gantry at Space Launch Complex 3 at Vandenberg Air Force Base in California, technicians and engineers prepare batteries for installation in NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander. InSight will be the first mission to look deep beneath the Martian surface. It will study the planet's interior by measuring its heat output and listen for marsquakes. The spacecraft will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created. InSight is scheduled for liftoff May 5, 2018.

Site-conditions map for Portugal based on VS measurements: methodology and final model

NASA Astrophysics Data System (ADS)

Vilanova, Susana; Narciso, João; Carvalho, João; Lopes, Isabel; Quinta Ferreira, Mario; Moura, Rui; Borges, José; Nemser, Eliza; Pinto, carlos

2017-04-01

In this paper we present a statistically significant site-condition model for Portugal based on shear-wave velocity (VS) data and surface geology. We also evaluate the performance of commonly used Vs30 proxies based on exogenous data and analyze the implications of using those proxies for calculating site amplification in seismic hazard assessment. The dataset contains 161 Vs profiles acquired in Portugal in the context of research projects, technical reports, academic thesis and academic papers. The methodologies involved in characterizing the Vs structure at the sites in the database include seismic refraction, multichannel analysis of seismic waves and refraction microtremor. Invasive measurements were performed in selected locations in order to compare the Vs profiles obtained from both invasive and non-invasive techniques. In general there was good agreement in the subsurface structure of Vs30 obtained from the different methodologies. The database flat-file includes information on Vs30, surface geology at 1:50.000 and 1:500.000 scales, elevation and topographic slope and based on SRTM30 topographic dataset. The procedure used to develop the site-conditions map is based on a three-step process that includes defining a preliminary set of geological units based on the literature, performing statistical tests to assess whether or not the differences in the distributions of Vs30 are statistically significant, and merging of the geological units accordingly. The dataset was, to some extent, affected by clustering and/or preferential sampling and therefore a declustering algorithm was applied. The final model includes three geological units: 1) Igneous, metamorphic and old (Paleogene and Mesozoic) sedimentary rocks; 2) Neogene and Pleistocene formations, and 3) Holocene formations. The evaluation of proxies indicates that although geological analogues and topographic slope are in general unbiased, the latter shows significant bias for particular geological units and subsequently for some geographical regions.

Thickness and geometry of Cenozoic deposits in California Wash area, Nevada, based on gravity and seismic-reflection data

USGS Publications Warehouse

Langenheim, V.E.; Miller, J.J.; Page, W.R.; Grow, J.A.

2001-01-01

Gravity and seismic-reflection data provide insights into the subsurface stratigraphy and structure of the California Wash area of southern Nevada. This area is part of the Lower Colorado flow system and stratigraphic and structural data are important inputs into developing the hydrogeologic framework. These data indicate that the basin beneath California Wash reaches depths of 2-3 km. The eastern margin of the basin coincides with a system of young (Quaternary and late Tertiary) faults, although both seismic and gravity data indicate that the major basin-bounding fault is 2-3 km west of the mapped young faults. Dry Lake Valley, the adjacent valley to the west, is characterized by thinner basin fill. The basin configuration beneath both California Wash and Dry Lake Valleys based on the inversion of gravity data is unconstrained because of the lack of gravity stations north of 36030?. Broad aeromagnetic anomalies beneath pre-Cenozoic basement in the Muddy Mountains and Arrow Canyon Range reflect Precambrian basement at depths of ~ 5 km. These rocks are probably barriers to ground-water flow,except where fractured.

Seismic- and well-log-inferred gas hydrate accumulations on Richards Island

USGS Publications Warehouse

Collett, T.S.

1999-01-01

The gas hydrate stability zone is areally extensive beneath most of the Mackenzie Delta-Beaufort Sea region, with the base of the gas hydrate stability zone more than 1000 m deep on Richards Island. In this study, gas hydrate has been inferred to occur in nine Richards Island exploratory wells on the basis of well-log responses calibrated to the response of the logs within the cored gas-hydrate-bearing intervals of the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well. The integration of the available well-log data with more than 240 km of industry-acquired reflection seismic data have allowed us to map the occurrence of four significant gas hydrate and associated free-gas accumulations in the Ivik-Mallik-Taglu area on Richards Island. The occurrence of gas hydrate on Richards Island is mostly restricted to the crest of large anticlinal features that cut across the base of the gas hydrate stability zone. Combined seismic and well-log data analysis indicate that the known and inferred gas hydrate accumulations on Richards Island may contain as much as 187 178106 m3 of gas.

USGS Tweet Earthquake Dispatch (@USGSted): Using Twitter for Earthquake Detection and Characterization

NASA Astrophysics Data System (ADS)

Liu, S. B.; Bouchard, B.; Bowden, D. C.; Guy, M.; Earle, P.

2012-12-01

The U.S. Geological Survey (USGS) is investigating how online social networking services like Twitter—a microblogging service for sending and reading public text-based messages of up to 140 characters—can augment USGS earthquake response products and the delivery of hazard information. The USGS Tweet Earthquake Dispatch (TED) system is using Twitter not only to broadcast seismically-verified earthquake alerts via the @USGSted and @USGSbigquakes Twitter accounts, but also to rapidly detect widely felt seismic events through a real-time detection system. The detector algorithm scans for significant increases in tweets containing the word "earthquake" or its equivalent in other languages and sends internal alerts with the detection time, tweet text, and the location of the city where most of the tweets originated. It has been running in real-time for 7 months and finds, on average, two or three felt events per day with a false detection rate of less than 10%. The detections have reasonable coverage of populated areas globally. The number of detections is small compared to the number of earthquakes detected seismically, and only a rough location and qualitative assessment of shaking can be determined based on Tweet data alone. However, the Twitter detections are generally caused by widely felt events that are of more immediate interest than those with no human impact. The main benefit of the tweet-based detections is speed, with most detections occurring between 19 seconds and 2 minutes from the origin time. This is considerably faster than seismic detections in poorly instrumented regions of the world. Going beyond the initial detection, the USGS is developing data mining techniques to continuously archive and analyze relevant tweets for additional details about the detected events. The information generated about an event is displayed on a web-based map designed using HTML5 for the mobile environment, which can be valuable when the user is not able to access a desktop computer at the time of the detections. The continuously updating map displays geolocated tweets arriving after the detection and plots epicenters of recent earthquakes. When available, seismograms from nearby stations are displayed as an additional form of verification. A time series of tweets-per-minute is also shown to illustrate the volume of tweets being generated for the detected event. Future additions are being investigated to provide a more in-depth characterization of the seismic events based on an analysis of tweet text and content from other social media sources.

Climate services for adapting landslide hazard prevention measures in the Vrancea Seismic Region

NASA Astrophysics Data System (ADS)

Micu, Dana; Balteanu, Dan; Jurchescu, Marta; Sima, Mihaela; Micu, Mihai

2014-05-01

The Vrancea Seismic Region is covering an area of about 8 000 km2 in the Romanian Curvature Carpathians and Subcarpathians and it is considered one of Europe's most intensely multi-hazard-affected areas. Due to its geomorphic traits (heterogeneous morphostructural units of flysch mountains and molasse hills and depressions), the area is strongly impacted by extreme hydro-meteorological events which are potentially enhancing the numerous damages inflicted to a dense network of human settlements. An a priori knowledge of future climate change is a useful climate service for local authorities to develop regional adapting strategies and adequate prevention/preparedness frameworks. This paper aims at integrating the results of the high-resolution climate projections over the 21st century (within the FP7 ECLISE project) into the regional landslide hazard assessment. The requirements of users (Civil Protection, Land management, local authorities) for this area refer to reliable and high-resolution spatial data on landslide and flood hazard for short and medium-term risk management strategies. An insight into the future behavior of climate variability in the Vrancea Seismic Region, based on future climate projections of three regional models, under three RCPs (2.6, 4.5, 8.6), suggests a clear warming, both annually and seasonally and a rather limited annual precipitation decrease, but with a strong change of seasonality. A landslide inventory of 2485 cases (shallow and medium seated earth, debris and rock slides and earth and debris flows) was obtained based on large scale geomorphological mapping and aerial photos support (GeoEye, DigitalGlobe; provided by GoogleEarth and BingMaps). The landslides are uniformly distributed across the area, being considered representative for the entire morphostructural environment. Landslide susceptibility map was obtained using multivariate statistical analysis (logistic regression), while a relative landslide hazard index was computed based on semi-quantitative spatial multi-criteria evaluation (SMCE). The generation of the landslide hazard maps relies on the heuristic approach, since a historical record of landslide occurrences, necessary to produce magnitude-frequency relations, is lacking. Based on the assumption of Sanderson et al. (1996) that slopes' morphology has adjusted, since the last glaciation, to the region's "normal" climatic conditions in all aspects including failures, it becomes clear that an extreme character of precipitation would be highly likely to generate landslides. Therefore, in order to represent the landslides triggering factor, raster maps for both time horizons (present and future) as simulated within each climate scenario have been used to illustrate the probabilistic seasonal precipitation amounts expected within a 30-year and a 100-year return period respectively. These maps, considered reliable indicators for depicting the changes in landslide occurrence probability, were standardized according to their contribution to hazard before being included in the SMCE together with the susceptibility map. The resulted hazard index maps for the two time horizons were compared aiming at detecting the future potential climate-induced changes in the spatial patterns of landslide occurrence. The outcomes mostly meet the requirements for updating the regional landslide risk management strategies.

Opportunities for Undergraduates to Engage in Research Using Seismic Data and Data Products

NASA Astrophysics Data System (ADS)

Taber, J. J.; Hubenthal, M.; Benoit, M. H.

2014-12-01

Introductory Earth science classes can become more interactive through the use of a range of seismic data and models that are available online, which students can use to conduct simple research regarding earthquakes and earth structure. One way to introduce students to these data sets is via a new set of six intro-level classroom activities designed to introduce undergraduates to some of the grand challenges in seismology research. The activities all use real data sets and some require students to collect their own data, either using physical models or via Web sites and Web applications. While the activities are designed to step students through a learning sequence, several of the activities are open-ended and can be expanded to research topics. For example, collecting and analyzing data from a deceptively simple physical model of earthquake behavior can lead students to query a map-based seismicity catalog via the IRIS Earthquake Browser to study seismicity rates and the distribution of earthquake magnitudes, and make predictions about the earthquake hazards in regions of their choosing. In another activity, students can pose their own questions and reach conclusions regarding the correlation between hydraulic fracturing, waste water disposal, and earthquakes. Other data sources are available for students to engage in self-directed research projects. For students with an interest in instrumentation, they can conduct research relating to instrument calibration and sensitivity using a simple educational seismometer. More advanced students can explore tomographic models of seismic velocity structure, and examine research questions related to earth structure, such as the correlation of topography to crustal thickness, and the fate of subducted slabs. The type of faulting in a region can be explored using a map-based catalog of focal mechanisms, allowing students to analyze the spatial distribution of normal, thrust and strike-slip events in a subduction zone region. For all of these topics and data sets, the societal impact of earthquakes can provide an additional motivation for students to engage in their research. www.iris.edu

Seismicity map of the state of Arizona

USGS Publications Warehouse

Stover, C.W.; Reagor, B.G.; Algermissen, S.T.

1986-01-01

This map is one of a series of seismicity maps produced by the U. S. Geological Survey that show earthquake data of individual states or groups of states at the scale of 1:1,000,000. This map shows only those earthquakes with epicenters located within the boundaries of Arizona, even though earthquakes in nearby states or countries may have been felt or may have caused damage in Arizona.The data in table 1 were used to compile the seismicity map; these data are a corrected, expanded, and updated (through 1982) version of the data used by Algermissen (1969) for a study of seismic risk in the United States. The locations and intensities of some earthquakes were revised and intensities were assigned where none had been before. Many earthquakes were added to the original list from new data sources as well as from some old data sources that had not been previously used. The data in table 1 represent best estimates of the location of the epicenter, magnitude, and intensity of each earthquake on the basis of historical and current information. Some of the aftershocks from large earthquakes are listed, but not all, especially for earthquakes that occurred before seismic instruments were universally used.Table 1 includes earthquakes reported felt in Yuma, Arizona that had no corroborating reports from other areas. These events are listed with coordinates (32.7°N., 114.6° W.) near Yuma even though it is suspected that they may have actually occurred in the Imperial Valley, California or Baja California, Mexico. Very few earthquakes have been instrumentally located near Yuma and it is believed that most historical felt reports correspond to earthquakes that occurred in the seismic zone extending from the Gulf of California northward into California. It is known that some earthquakes located graphically from phase data prior to epicenter determinations by electronic computer were erroneously located in southern Arizona and actually had locations in the Gulf of California or northern Mexico.For detailed descriptions of the effects of earthquakes in Arizona see Bulletin 193, Arizona earthquakes, 1776-1980 (reference 343) which lists the localities where the earthquakes were felt and the effects at each place. This publication also includes isoseismal maps for 41 events.The latitude and longitude coordinates of each epicenter were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped and counted. These locations are represented on the map by a triangle. The number of earthquakes at each location is shown on the map by the arabic number to the right of the triangle. The Roman numeral to the left of the triangle is the maximum Modified Mercalli intensity (Wood and Neumann, 1931) of al 1 earthquakes with epicenters at that geographic location. The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. The year shown below each triangle is the latest year for which the maximum intensity was recorded.

Seismic Characterization and Continuity Analysis of Gas Hydrate Horizons Near the Mallik Research Wells, Mackenzie Delta, Canada

NASA Astrophysics Data System (ADS)

Bellefleur, G.; Riedel, M.; Brent, T.

2005-12-01

Gas hydrate deposits in arctic environment generally lack the BSR signature diagnostic of their presence in marine seismic data. The absence of the BSR signature complicates the estimation of the resources within or below the permafrost and the determination of their potential impact on future energy supplies, geohazard and climate change. We present results from a detailed seismic characterization of three gas hydrate horizons (A, B and C) intersected below the permafrost in five wells of the Mallik gas hydrate field located in the Mackenzie delta (Northwest Territories, Canada). The detailed seismic characterization included attribute analyses, synthetic modeling and acoustic impedance inversion and allowed estimation of the lateral continuity of the three horizons in the vicinity of the wells. Vertical Seismic Profiling (VSP) data, 3D and 2D industry seismic data and the 5L/2L-38 geophysical logs (density, P-wave sonic velocity) were used for this study. Synthetic modeling using the sonic and density logs reveals that the base of the lower gas hydrate horizons B and C can be identified on the industry 3D and 2D seismic sections as prominent isolated reflections. The uppermost gas hydrate occurrence (horizon A) and potentially other additional smaller-scale layers are identified only on the higher-resolution VSP data. The 3D industry seismic data set processed to preserve the relative true-amplitudes was used for attribute calculations and acoustic impedance inversion. The attribute maps defined areas of continuous reflectivity for horizons B and C and structural features disrupting them. Results from impedance inversion indicate that such continuous reflectivity around the wells is most likely attributable to gas hydrates. The middle gas hydrate occurrence (horizon B) covers an area of approximately 25 000m2. Horizon C, which marks the base of gas hydrate occurrence zone, extends over a larger area of approximately 120 000m2.

RSEIS and RFOC: Seismic Analysis in R

NASA Astrophysics Data System (ADS)

Lees, J. M.

2015-12-01

Open software is essential for reproducible scientific exchange. R-packages provide a platform for development of seismological investigation software that can be properly documented and traced for data processing. A suite of R packages designed for a wide range of seismic analysis is currently available in the free software platform called R. R is a software platform based on the S-language developed at Bell Labs decades ago. Routines in R can be run as standalone function calls, or developed in object-oriented mode. R comes with a base set of routines, and thousands of user developed packages. The packages developed at UNC include subroutines and interactive codes for processing seismic data, analyzing geographic information (GIS) and inverting data involved in a variety of geophysical applications. On CRAN (Comprehensive R Archive Network, http://www.r-project.org/) currently available packages related to seismic analysis are RSEIS, Rquake, GEOmap, RFOC, zoeppritz, RTOMO, and geophys, Rwave, PEIP, hht, rFDSN. These include signal processing, data management, mapping, earthquake location, deconvolution, focal mechanisms, wavelet transforms, Hilbert-Huang Transforms, tomographic inversion, and Mogi deformation among other useful functionality. All software in R packages is required to have detailed documentation, making the exchange and modification of existing software easy. In this presentation, I will focus on packages RSEIS and RFOC, showing examples from a variety of seismic analyses. The R approach has similarities to the popular (and expensive) MATLAB platform, although R is open source and free to down load.

Possible Impact Origin for the Late Ordovician Bear Swamp Structure in the Finger Lakes Region of New York

NASA Astrophysics Data System (ADS)

Leiphart, D.

2010-12-01

Impact structures, or astroblemes, are one of rarest formations in the geologic record. Presently there are 176 confirmed impact structures on the planet with roughly two-thirds of them evident at the surface. A potential impact structure has been discovered in a 3D seismic survey in the Finger Lakes Region of upstate New York (Figure 1 - N42o43.187’; W76o16.637’). The Bear Swamp crater is uppermost Ordovician (~444 Ma) in age and is situated within the fluvial-deltaic to shallow marine Queenston Formation. This nearly circular structure measures 3.5 km (2.2 mi) in diameter and is completely buried in the subsurface at a depth of approximately 1,220 m (4,000 ft). Seismic data show a central uplift within the crater that rises about 160 m (525 ft) above the base. Around the central uplift is an annular basin that is more than 300 m (~1,000 ft) thick and is characterized by synformal seismic reflectors (Figure 1). This three-dimensional morphology resembles other complex craters of confirmed impact origin. Two exploration wells were drilled into the crater and image logs were run. The first well tested the central rebound which consists of steeply dipping beds and heavily brecciated zones. The second well was drilled in the annular basin which contains alternating sequences of chaotic zones and shallow dipping beds. Based on analogous impact structures, this crater fill is here interpreted as resurge breccias and turbidites which were the result of intense wave action in the moments after impact. Above these impact-related deposits lies a zone of very thin (~2cm) laminae which resemble varved sediments in lacustrine environments. A bioturbated zone overlies these thin laminae, which is in turn capped by the End Ordovician unconformity. Observations of both seismic and well data are consistent with a shallow marine to transition zone impact origin for the Bear Swamp crater. Figure 1: Location map showing the area of the ~180 km2 (70 mi2) 3D seismic survey and the proposed Bear Swamp Astrobleme. The map in the lower left is a time slice through a coherency volume at 650 milliseconds. The inset at the lower right is a cutout of the 3D volume with the Queenston top and base crater horizon extrapolated out.

Active fault databases and seismic hazard calculations: a compromise between science and practice. Review of case studies from Spain.

NASA Astrophysics Data System (ADS)

Garcia-Mayordomo, Julian; Martin-Banda, Raquel; Insua-Arevalo, Juan Miguel; Alvarez-Gomez, Jose Antonio; Martinez-Diaz, Jose Jesus

2017-04-01

Since the Quaternary Active Faults Database of Iberia (QAFI) was released in February 2012 a number of studies aimed at producing seismic hazard assessments have made use of it. We will present a summary of the shortcomings and advantages that were faced when QAFI was considered in different seismic hazard studies. These include the production of the new official seismic hazard map of Spain, performed in the view of the foreseen adoption of Eurocode-8 throughout 2017. The QAFI database was considered as a complementary source of information for designing the seismogenic source-zone models used in the calculations, and particularly for the estimation of maximum magnitude distribution in each zone, as well as for assigning the predominant rupture mechanism based on style of faulting. We will also review the different results obtained by other studies that considered QAFI faults as independent seismogenic-sources in opposition to source-zones, revealing, on one hand, the crucial importance of data-reliability and, on the other, the very much influence that ground motion attenuation models have on the actual impact of fault-sources on hazard results. Finally, we will present briefly the updated version of the database (QAFI v.3, 2015), which includes an original scheme for evaluating the reliability of fault seismic parameters specifically devised to facilitate decision-making to seismic hazard practitioners.

Refining the Tonga Slab Geometry Using Slab Phases of Seismic Waves

NASA Astrophysics Data System (ADS)

Alongi, T.; Wei, S. S.; Blackman, D. K.

2017-12-01

Although the Tonga subducting slab geometry has been previously mapped by earthquake distribution, its detailed morphology is poorly constrained. The uncertainties of the slab surface relative to earthquakes can be translated into large errors in predicted temperature of hypocenters that is considered as a chief control of intermediate-depth seismicity. Seismic waves converted at the interface between the slab crust and the overlying mantle wedge can provide additional constraints on the location of the slab surface. A PS phase converted at the slab interface is observable in the horizontal components, whereas an SP converted phase can be seen in the vertical component. In this study, we analyze PS and SP phases in the seismic dataset of the 2009-2010 Ridge2000 Lau Spreading Center project, which consisted of 50 ocean bottom seismographs (OBSs) and 17 island-based seismic stations deployed in Fiji, Tonga, and the Lau Basin for about one year. More than 1,000 PS arrivals from local events were manually picked, predominantly with a 1-3 Hz filter. Next, the PS-P differential travel times will be inverted to determine improved depths of the slab surface relative to the local earthquakes and the receiving stations. The refined slab geometry will allow us to assess the thermal structure and dehydration reactions of the Tonga slab, lending further insight into the mechanisms of intermediate-depth seismicity.

Contemporary seismicity in and around the Yakima Fold and Thrust Belt in eastern Washington

USGS Publications Warehouse

Gomberg, J.; Sherrod, B.; Trautman, M.; Burns, E.; Snyder, Diane

2012-01-01

We examined characteristics of routinely cataloged seismicity from 1970 to the present in and around the Yakima fold‐and‐thrust belt (YFTB) in eastern Washington to determine if the characteristics of contemporary seismicity provide clues about regional‐scale active tectonics or about more localized, near‐surface processes. We employed new structural and hydrologic models of the Columbia River basalts (CRB) and found that one‐third to one‐half of the cataloged earthquakes occur within the CRB and that these CRB earthquakes exhibit significantly more clustered, and swarmlike, behavior than those outside. These results and inferences from published studies led us to hypothesize that clustered seismicity is likely associated with hydrologic changes in the CRB, which hosts the regional aquifer system. While some general features of the regional groundwater system support this hypothesis, seismicity patterns and mapped long‐term changes in groundwater levels and present‐day irrigation neither support nor refute it. Regional tectonic processes and crustal‐scale structures likely influence the distribution of earthquakes both outside and within the CRB as well. We based this inference on qualitatively assessed alignments between the dominant northwest trends in the geologic structure and the seismicity generally and between specific faults and characteristics of the 2009 Wooded Island swarm and aseismic slip, which is the only cluster studied in detail and the most vigorous since regional monitoring began.

How well can we test probabilistic seismic hazard maps?

NASA Astrophysics Data System (ADS)

Vanneste, Kris; Stein, Seth; Camelbeeck, Thierry; Vleminckx, Bart

2017-04-01

Recent large earthquakes that gave rise to shaking much stronger than shown in probabilistic seismic hazard (PSH) maps have stimulated discussion about how well these maps forecast future shaking. These discussions have brought home the fact that although the maps are designed to achieve certain goals, we know little about how well they actually perform. As for any other forecast, this question involves verification and validation. Verification involves assessing how well the algorithm used to produce hazard maps implements the conceptual PSH model ("have we built the model right?"). Validation asks how well the model forecasts the shaking that actually occurs ("have we built the right model?"). We explore the verification issue by simulating shaking histories for an area with assumed uniform distribution of earthquakes, Gutenberg-Richter magnitude-frequency relation, Poisson temporal occurrence model, and ground-motion prediction equation (GMPE). We compare the maximum simulated shaking at many sites over time with that predicted by a hazard map generated for the same set of parameters. The Poisson model predicts that the fraction of sites at which shaking will exceed that of the hazard map is p = 1 - exp(-t/T), where t is the duration of observations and T is the map's return period. Exceedance is typically associated with infrequent large earthquakes, as observed in real cases. The ensemble of simulated earthquake histories yields distributions of fractional exceedance with mean equal to the predicted value. Hence, the PSH algorithm appears to be internally consistent and can be regarded as verified for this set of simulations. However, simulated fractional exceedances show a large scatter about the mean value that decreases with increasing t/T, increasing observation time and increasing Gutenberg-Richter a-value (combining intrinsic activity rate and surface area), but is independent of GMPE uncertainty. This scatter is due to the variability of earthquake recurrence, and so decreases as the largest earthquakes occur in more simulations. Our results are important for evaluating the performance of a hazard map based on misfits in fractional exceedance, and for assessing whether such misfit arises by chance or reflects a bias in the map. More specifically, we determined for a broad range of Gutenberg-Richter a-values theoretical confidence intervals on allowed misfits in fractional exceedance and on the percentage of hazard-map bias that can thus be detected by comparison with observed shaking histories. Given that in the real world we only have one shaking history for an area, these results indicate that even if a hazard map does not fit the observations, it is very difficult to assess its veracity, especially for low-to-moderate-seismicity regions. Because our model is a simplified version of reality, any additional uncertainty or complexity will tend to widen these confidence intervals.

Lithospheric strucutre and relationship to seismicity beneath the Southeastern US using reciever functions

NASA Astrophysics Data System (ADS)

Cunningham, E.; Lekic, V.

2017-12-01

Despite being on a passive margin for millions of years, the Southeastern United States (SEUS) contains numerous seismogenic zones with the ability to produce damaging earthquakes. However, mechanisms controlling these intraplate earthquakes are poorly understood. Recently, Biryol et al. 2016 use P-wave tomography suggest that upper mantle structures beneath the SEUS correlate with areas of seismicity and seismic quiescence. Specifically, thick and fast velocity lithosphere beneath North Carolina is stable and indicative of areas of low seismicity. In contrast, thin and slow velocity lithosphere is weak, and the transition between the strong and weak lithosphere may be correlated with seismogenic zones found in the SEUS. (eg. Eastern Tennessee seismic zone and the Central Virginia seismic zone) Therefore, I systematically map the heterogeneity of the mantle lithosphere using converted seismic waves and quantify the spatial correlation between seismicity and lithospheric structure. The extensive network of seismometers that makes up the Earthscope USArray combined with the numerous seismic deployments in the Southeastern United States allows for unprecedented opportunity to map changes in lithospheric structure across seismogenic zones and seismic quiescent regions. To do so, I will use both P-to-s and S-to-p receiver functions (RFS). Since RFs are sensitive to seismic wavespeeds and density discontinuities with depth, they particularly useful for studying lithospheric structure. Ps receiver functions contain high frequency information allowing for high resolution, but can become contaminated by large sediment signals; therefore, I removed sediment multiples and correct for time delays of later phases using the method of Yu et. al 2015 which will allow us to see later arriving phases associated with lithospheric discontinuities. S-to-p receiver functions are not contaminated by shallow layers, making them ideal to study deep lithospheric structures but they can suffer from low signal-to-noise levels. I compensate for this difficulty by using high quality deployments and stacking these data at common conversion points to increase lateral resolution.

Seismic stratigraphy and tomography in the outer shelf and slope of the Central Basin, Ross Sea, Antarctica

NASA Astrophysics Data System (ADS)

Kim, Sookwan; De Santis, Laura; Böhm, Gualtiero; Kuk Hong, Jong; Jin, Young Keun; Geletti, Riccardo; Wardell, Nigel; Petronio, Lorenzo; Colizza, Ester

2014-05-01

The Ross Sea, located between Victoria Land and Marie Byrd Land in Antarctica, is one of the main drainage of the Antarctic Ice Sheet (AIS). Reflection seismic data acquired by many countries during several decades have provided insights into the history of the Ross Sea and the AIS evolution. However the majority of the existing seismic data are concentrated in the shelf area, where hiatus formed by grounding ice sheet erosion multiple events prevent to reconstruct the entire sedimentary sequences depositional evolution. On the outer shelf and upper slope, the sedimentary sequences are relatively well preserved. The main purpose of this study is the investigation of the Cenozoic Antarctic Ice Sheet evolution through the seismic sequence analysis of the outer shelf and slope of the Central Basin, in the Ross Sea. The data used are the new multi-channel seismic data, KSL12, were acquired on the outer shelf and upper slope of the Central Bain in February 2013 by Korea Polar Research Institute. The reflection seismic data, previously collected by the Italian Antarctic Program (PNRA) and other data available from the Seismic Data Library System (SDLS) are also used for velocity tomography and seismic sequence mapping. The seismic data were processed by a conventional processing flow to produce the seismic profiles. Preliminary results show well-developed prograding wedges at the mouth of glacial troughs, eroded by a major glacial unconformity, the Ross Sea Unconformity 4 (RSU-4), correlated to a main event between early- and mid-Miocene. The velocity anomalies shown along KSL12-1 can be interpreted as showing the occurrence of gas and fluids, diagenetic horizons and sediment compactions. The isopach maps of each sequence show the variation of thickness of the sediments depocenter shift. The seismic sequence stratigraphy and acoustic facies analysis provide information about different phases of ice sheet's advance and retreat related to the AIS Cenozoic dynamics.

Crustal structure of northern Italy from the ellipticity of Rayleigh waves

NASA Astrophysics Data System (ADS)

Berbellini, Andrea; Morelli, Andrea; G. Ferreira, Ana M.

2017-04-01

Northern Italy is a diverse geological region, including the wide and thick Po Plain sedimentary basin, which is bounded by the Alps and the Apennines. The seismically slow shallow structure of the Po Plain is difficult to retrieve with classical seismic measurements such as surface wave dispersion, yet the detailed structure of the region greatly affects seismic wave propagation and hence seismic ground shaking. Here we invert Rayleigh wave ellipticity measurements in the period range 10-60 s for 95 stations in northern Italy using a fully non linear approach to constrain vertical vS,vP and density profiles of the crust beneath each station. The ellipticity of Rayleigh wave ground motion is primarily sensitive to shear-wave velocity beneath the recording station, which reduces along-path contamination effects. We use the 3D layering structure in MAMBo, a previous model based on a compilation of geological and geophysical information for the Po Plain and surrounding regions of northern Italy, and employ ellipticity data to constrain vS,vP and density within its layers. We show that ellipticity data from ballistic teleseismic wave trains alone constrain the crustal structure well. This leads to MAMBo-E, an updated seismic model of the region's crust that inherits information available from previous seismic prospection and geological studies, while fitting new seismic data well. MAMBo-E brings new insights into lateral heterogeneity in the region's subsurface. Compared to MAMBo, it shows overall faster seismic anomalies in the region's Quaternary, Pliocene and Oligo-Miocene layers and better delineates the seismic structures of the Po Plain at depth. Two low velocity regions are mapped in the Mesozoic layer in the western and eastern parts of the Plain, which seem to correspond to the Monferrato sedimentary basin and to the Ferrara-Romagna thrust system, respectively.

Probabilistic seismic hazard assessments of Sabah, east Malaysia: accounting for local earthquake activity near Ranau

NASA Astrophysics Data System (ADS)

Khalil, Amin E.; Abir, Ismail A.; Ginsos, Hanteh; Abdel Hafiez, Hesham E.; Khan, Sohail

2018-02-01

Sabah state in eastern Malaysia, unlike most of the other Malaysian states, is characterized by common seismological activity; generally an earthquake of moderate magnitude is experienced at an interval of roughly every 20 years, originating mainly from two major sources, either a local source (e.g. Ranau and Lahad Dato) or a regional source (e.g. Kalimantan and South Philippines subductions). The seismicity map of Sabah shows the presence of two zones of distinctive seismicity, these zones are near Ranau (near Kota Kinabalu) and Lahad Datu in the southeast of Sabah. The seismicity record of Ranau begins in 1991, according to the international seismicity bulletins (e.g. United States Geological Survey and the International Seismological Center), and this short record is not sufficient for seismic source characterization. Fortunately, active Quaternary fault systems are delineated in the area. Henceforth, the seismicity of the area is thus determined as line sources referring to these faults. Two main fault systems are believed to be the source of such activities; namely, the Mensaban fault zone and the Crocker fault zone in addition to some other faults in their vicinity. Seismic hazard assessments became a very important and needed study for the extensive developing projects in Sabah especially with the presence of earthquake activities. Probabilistic seismic hazard assessments are adopted for the present work since it can provide the probability of various ground motion levels during expected from future large earthquakes. The output results are presented in terms of spectral acceleration curves and uniform hazard curves for periods of 500, 1000 and 2500 years. Since this is the first time that a complete hazard study has been done for the area, the output will be a base and standard for any future strategic plans in the area.

Faulting apparently related to the 1994 Northridge, California, earthquake and possible co-seismic origin of surface cracks in Potrero Canyon, Los Angeles County, California

USGS Publications Warehouse

Catchings, R.D.; Goldman, M.R.; Lee, W.H.K.; Rymer, M.J.; Ponti, D.J.

1998-01-01

Apparent southward-dipping, reverse-fault zones are imaged to depths of about 1.5 km beneath Potrero Canyon, Los Angeles County, California. Based on their orientation and projection to the surface, we suggest that the imaged fault zones are extensions of the Oak Ridge fault. Geologic mapping by others and correlations with seismicity studies suggest that the Oak Ridge fault is the causative fault of the 17 January 1994 Northridge earthquake (Northridge fault). Our seismically imaged faults may be among several faults that collectively comprise the Northridge thrust fault system. Unusually strong shaking in Potrero Canyon during the Northridge earthquake may have resulted from focusing of seismic energy or co-seismic movement along existing, related shallow-depth faults. The strong shaking produced ground-surface cracks and sand blows distributed along the length of the canyon. Seismic reflection and refraction images show that shallow-depth faults may underlie some of the observed surface cracks. The relationship between observed surface cracks and imaged faults indicates that some of the surface cracks may have developed from nontectonic alluvial movement, but others may be fault related. Immediately beneath the surface cracks, P-wave velocities are unusually low (<400 m/sec), and there are velocity anomalies consistent with a seismic reflection image of shallow faulting to depths of at least 100 m. On the basis of velocity data, we suggest that unconsolidated soils (<800 m/sec) extend to depths of about 15 to 20 m beneath our datum (<25 m below ground surface). The underlying rocks range in velocity from about 1000 to 5000 m/sec in the upper 100 m. This study illustrates the utility of high-resolution seismic imaging in assessing local and regional seismic hazards.

Comparison of smoothing methods for the development of a smoothed seismicity model for Alaska and the implications for seismic hazard

NASA Astrophysics Data System (ADS)

Moschetti, M. P.; Mueller, C. S.; Boyd, O. S.; Petersen, M. D.

2013-12-01

In anticipation of the update of the Alaska seismic hazard maps (ASHMs) by the U. S. Geological Survey, we report progress on the comparison of smoothed seismicity models developed using fixed and adaptive smoothing algorithms, and investigate the sensitivity of seismic hazard to the models. While fault-based sources, such as those for great earthquakes in the Alaska-Aleutian subduction zone and for the ~10 shallow crustal faults within Alaska, dominate the seismic hazard estimates for locations near to the sources, smoothed seismicity rates make important contributions to seismic hazard away from fault-based sources and where knowledge of recurrence and magnitude is not sufficient for use in hazard studies. Recent developments in adaptive smoothing methods and statistical tests for evaluating and comparing rate models prompt us to investigate the appropriateness of adaptive smoothing for the ASHMs. We develop smoothed seismicity models for Alaska using fixed and adaptive smoothing methods and compare the resulting models by calculating and evaluating the joint likelihood test. We use the earthquake catalog, and associated completeness levels, developed for the 2007 ASHM to produce fixed-bandwidth-smoothed models with smoothing distances varying from 10 to 100 km and adaptively smoothed models. Adaptive smoothing follows the method of Helmstetter et al. and defines a unique smoothing distance for each earthquake epicenter from the distance to the nth nearest neighbor. The consequence of the adaptive smoothing methods is to reduce smoothing distances, causing locally increased seismicity rates, where seismicity rates are high and to increase smoothing distances where seismicity is sparse. We follow guidance from previous studies to optimize the neighbor number (n-value) by comparing model likelihood values, which estimate the likelihood that the observed earthquake epicenters from the recent catalog are derived from the smoothed rate models. We compare likelihood values from all rate models to rank the smoothing methods. We find that adaptively smoothed seismicity models yield better likelihood values than the fixed smoothing models. Holding all other (source and ground motion) models constant, we calculate seismic hazard curves for all points across Alaska on a 0.1 degree grid, using the adaptively smoothed and fixed smoothed seismicity models separately. Because adaptively smoothed models concentrate seismicity near the earthquake epicenters where seismicity rates are high, the corresponding hazard values are higher, locally, but reduced with distance from observed seismicity, relative to the hazard from fixed-bandwidth models. We suggest that adaptively smoothed seismicity models be considered for implementation in the update to the ASHMs because of their improved likelihood estimates relative to fixed smoothing methods; however, concomitant increases in seismic hazard will cause significant changes in regions of high seismicity, such as near the subduction zone, northeast of Kotzebue, and along the NNE trending zone of seismicity in the Alaskan interior.

Comparison of smoothing methods for the development of a smoothed seismicity model for Alaska and the implications for seismic hazard

USGS Publications Warehouse

Moschetti, Morgan P.; Mueller, Charles S.; Boyd, Oliver S.; Petersen, Mark D.

2014-01-01

In anticipation of the update of the Alaska seismic hazard maps (ASHMs) by the U. S. Geological Survey, we report progress on the comparison of smoothed seismicity models developed using fixed and adaptive smoothing algorithms, and investigate the sensitivity of seismic hazard to the models. While fault-based sources, such as those for great earthquakes in the Alaska-Aleutian subduction zone and for the ~10 shallow crustal faults within Alaska, dominate the seismic hazard estimates for locations near to the sources, smoothed seismicity rates make important contributions to seismic hazard away from fault-based sources and where knowledge of recurrence and magnitude is not sufficient for use in hazard studies. Recent developments in adaptive smoothing methods and statistical tests for evaluating and comparing rate models prompt us to investigate the appropriateness of adaptive smoothing for the ASHMs. We develop smoothed seismicity models for Alaska using fixed and adaptive smoothing methods and compare the resulting models by calculating and evaluating the joint likelihood test. We use the earthquake catalog, and associated completeness levels, developed for the 2007 ASHM to produce fixed-bandwidth-smoothed models with smoothing distances varying from 10 to 100 km and adaptively smoothed models. Adaptive smoothing follows the method of Helmstetter et al. and defines a unique smoothing distance for each earthquake epicenter from the distance to the nth nearest neighbor. The consequence of the adaptive smoothing methods is to reduce smoothing distances, causing locally increased seismicity rates, where seismicity rates are high and to increase smoothing distances where seismicity is sparse. We follow guidance from previous studies to optimize the neighbor number (n-value) by comparing model likelihood values, which estimate the likelihood that the observed earthquake epicenters from the recent catalog are derived from the smoothed rate models. We compare likelihood values from all rate models to rank the smoothing methods. We find that adaptively smoothed seismicity models yield better likelihood values than the fixed smoothing models. Holding all other (source and ground motion) models constant, we calculate seismic hazard curves for all points across Alaska on a 0.1 degree grid, using the adaptively smoothed and fixed smoothed seismicity models separately. Because adaptively smoothed models concentrate seismicity near the earthquake epicenters where seismicity rates are high, the corresponding hazard values are higher, locally, but reduced with distance from observed seismicity, relative to the hazard from fixed-bandwidth models. We suggest that adaptively smoothed seismicity models be considered for implementation in the update to the ASHMs because of their improved likelihood estimates relative to fixed smoothing methods; however, concomitant increases in seismic hazard will cause significant changes in regions of high seismicity, such as near the subduction zone, northeast of Kotzebue, and along the NNE trending zone of seismicity in the Alaskan interior.

Lithostratigraphic interpretation from joint analysis of seismic tomography and magnetotelluric resistivity models using self-organizing map techniques

NASA Astrophysics Data System (ADS)

Bauer, K.; Muñoz, G.; Moeck, I.

2012-12-01

The combined interpretation of different models as derived from seismic tomography and magnetotelluric (MT) inversion represents a more efficient approach to determine the lithology of the subsurface compared with the separate treatment of each discipline. Such models can be developed independently or by application of joint inversion strategies. After the step of model generation using different geophysical methodologies, a joint interpretation work flow includes the following steps: (1) adjustment of a joint earth model based on the adapted, identical model geometry for the different methods, (2) classification of the model components (e.g. model blocks described by a set of geophysical parameters), and (3) re-mapping of the classified rock types to visualise their distribution within the earth model, and petrophysical characterization and interpretation. One possible approach for the classification of multi-parameter models is based on statistical pattern recognition, where different models are combined and translated into probability density functions. Classes of rock types are identified in these methods as isolated clusters with high probability density function values. Such techniques are well-established for the analysis of two-parameter models. Alternatively we apply self-organizing map (SOM) techniques, which have no limitations in the number of parameters to be analysed in the joint interpretation. Our SOM work flow includes (1) generation of a joint earth model described by so-called data vectors, (2) unsupervised learning or training, (3) analysis of the feature map by adopting image processing techniques, and (4) application of the knowledge to derive a lithological model which is based on the different geophysical parameters. We show the usage of the SOM work flow for a synthetic and a real data case study. Both tests rely on three geophysical properties: P velocity and vertical velocity gradient from seismic tomography, and electrical resistivity from MT inversion. The synthetic data are used as a benchmark test to demonstrate the performance of the SOM method. The real data were collected along a 40 km profile across parts of the NE German basin. The lithostratigraphic model from the joint SOM interpretation consists of eight litho-types and covers Cenozoic, Mesozoic and Paleozoic sediments down to 5 km depth. There is a remarkable agreement between the SOM based model and regional marker horizons interpolated from surrounding 2D industrial seismic data. The most interesting results include (1) distinct properties of the Jurassic (low P velocity gradients, low resistivities) interpreted as the signature of shaly clastics, and (2) a pattern within the Upper Permian Zechstein with decreased resistivities and increased P velocities within the salt depressions on the one hand, and increased resistivities and decreased P velocities in the salt pillows on the other hand. In our interpretation this pattern is related with flow of less dense salt matrix components into the pillows and remaining brittle evaporites within the depressions.

Geographic deaggregation of seismic hazard in the United States

USGS Publications Warehouse

Harmsen, S.; Frankel, A.

2001-01-01

The seismic hazard calculations for the 1996 national seismic hazard maps have been geographically deaggregated to assist in the understanding of the relative contributions of sources. These deaggregations are exhibited as maps with vertical bars whose heights are proportional to the contribution that each geographical cell makes to the ground-motion exceedance hazard. Bar colors correspond to average source magnitudes. We also extend the deaggregation analysis reported in Harmsen et al. (1999) to the western conterminous United States. In contrast to the central and eastern United States (CEUS); the influence of specific faults or characteristic events can be clearly identified. Geographic deaggregation for 0.2-sec and 1.0-sec pseudo spectral acceleration (SA) is performed for 10% probability of exceedance (PE) in 50 yr (475-yr mean return period) and 2% PE in 50 yr (2475-yr mean return period) for four western U.S. cities, Los Angeles, Salt Lake City, San Francisco, and Seattle, and for three central and eastern U.S. cities, Atlanta, Boston, and Saint Louis. In general, as the PE is lowered, the sources of hazard closer to the site dominate. Larger, more distant earthquakes contribute more significantly to hazard for 1.0-sec SA than for 0.2-sec SA. Additional maps of geographically deaggregated seismic hazard are available on the Internet for 120 cities in the conterminous United States (http://geohazards. cr.usgs.gov/eq/) for 1-sec SA and for 0.2-sec SA with a 2% PE in 50 yr. Examination of these maps of hazard contributions enables the investigator to determine the distance and azimuth to predominant sources, and their magnitudes. This information can be used to generate scenario earthquakes and corresponding time histories for seismic design and retrofit. Where fault density is lower than deaggregation cell dimensions, we can identify specific faults that contribute significantly to the seismic hazard at a given site. Detailed fault information enables investigators to include rupture information such as source directivity, radiation pattern, and basin-edge effects into their scenario earthquakes used in engineering analyses.

Ground motion models used in the 2014 U.S. National Seismic Hazard Maps

USGS Publications Warehouse

Rezaeian, Sanaz; Petersen, Mark D.; Moschetti, Morgan P.

2015-01-01

The National Seismic Hazard Maps (NSHMs) are an important component of seismic design regulations in the United States. This paper compares hazard using the new suite of ground motion models (GMMs) relative to hazard using the suite of GMMs applied in the previous version of the maps. The new source characterization models are used for both cases. A previous paper (Rezaeian et al. 2014) discussed the five NGA-West2 GMMs used for shallow crustal earthquakes in the Western United States (WUS), which are also summarized here. Our focus in this paper is on GMMs for earthquakes in stable continental regions in the Central and Eastern United States (CEUS), as well as subduction interface and deep intraslab earthquakes. We consider building code hazard levels for peak ground acceleration (PGA), 0.2-s, and 1.0-s spectral accelerations (SAs) on uniform firm-rock site conditions. The GMM modifications in the updated version of the maps created changes in hazard within 5% to 20% in WUS; decreases within 5% to 20% in CEUS; changes within 5% to 15% for subduction interface earthquakes; and changes involving decreases of up to 50% and increases of up to 30% for deep intraslab earthquakes for most U.S. sites. These modifications were combined with changes resulting from modifications in the source characterization models to obtain the new hazard maps.

Comparing Newmark

NASA Astrophysics Data System (ADS)

Rodríguez-Peces, M. J.; García-Mayordomo, J.; Azañón-Hernández, J. M.; Jabaloy-Sánchez, A.

2009-04-01

The Lorca Basin (Eastern Betic Cordillera, SE Spain) is one of the most seismically active regions of Spain. In this area there are well known cases of earthquake-induced slope instabilities associated to specific earthquakes (e.g., Bullas 2002, La Paca 2005). Furthermore, this area is characterized by moderate magnitude seismicity which mainly produces rock-falls and avalanches. In this work we present the results of our research at regional and site scales. For the regional scale, we have used a geographic information system (GIS) to develop an implementation of the Newmark's sliding rigid block method. We have particularly proposed a new variation of Newmark's method to consider soil and topographic amplification effects. Subsequently, we produced "Newmark displacement" maps for both probabilistic and deterministic seismic scenarios in the Lorca Basin. Probabilistic seismic scenarios consider three hazard maps in terms of peak ground acceleration (PGA) on rock corresponding to the 475-, 975- and 2475-year return periods (exceedance probability of 10, 5 and 2% in 50 years, respectively) in the Murcia Region. Deterministic seismic scenarios consider the occurrence of the most probable earthquake for a 475-year return period (Mw=5.0) at every location, or either a complete rupture of Lorca-Totana (Mw=6.7) or Puerto Lumbreras-Lorca (Mw=6.8) segments of Alhama de Murcia Fault. The Newmark displacement maps allowed us to identify areas with the highest potential seismic hazard, and also locate areas for future particular studies. We have found that rock-falls produced during the last earthquakes in Lorca Basin (e.g., Bullas 2002, La Paca 2005) match very well with areas with values of Newmark displacement lower than 2 cm in all the seismic scenarios considered. Therefore, it seems that low values of Newmark displacements are very likely associated with rock-falls. To support this hypothesis we have applied the Newmark method at a site scale. To do this, we have selected La Paca rock-fall which was generated during La Paca 2005 earthquake (mbLg=4.7, IEMS=VI-VII). We have used a terrestrial laser scanner in order to obtain a high resolution digital elevation model of La Paca rock-fall area. Moreover, we have performed a back-analysis based on field data to estimate the static safety factor previous to the earthquake and the critical acceleration. Furthermore, we have selected a representative strong ground motion record for La Paca earthquake from international databases. The critical acceleration and the peak ground acceleration values obtained from the strong ground motion record allowed us to estimate the actual soil and topographic amplification effects. Finally, we have calculated analytically the real Newmark displacement at La Paca rock-fall and we have compared this displacement with our GIS estimation in order to improve the calibration of Newmark's method at the regional scale.

Micro-seismicity and seismic moment release within the Coso Geothermal Field, California

USGS Publications Warehouse

Kaven, Joern; Hickman, Stephen H.; Davatzes, Nicholas C.

2014-01-01

We relocate 16 years of seismicity in the Coso Geothermal Field (CGF) using differential travel times and simultaneously invert for seismic velocities to improve our knowledge of the subsurface geologic and hydrologic structure. We expand on our previous results by doubling the number of relocated events from April 1996 through May 2012 using a new field-wide 3-D velocity model. Relocated micro-seismicity sharpens in many portions of the active geothermal reservoir, likely defining large-scale fault zones and fluid pressure compartment boundaries. However, a significant fraction of seismicity remains diffuse and does not cluster into sharply defined structures, suggesting that permeability is maintained within the reservoir through distributed brittle failure. The seismic velocity structure reveals heterogeneous distributions of compressional (Vp) and shear (Vs) wave speed, with Vs generally higher in the Main Field and East Flank and Vp remaining relatively uniform across the CGF, but with significant local variations. The Vp/Vs ratio appears to outline the two main producing compartments of the reservoir at depths below mean ground level of approximately 1 to 2.5 km, with a ridge of relatively high Vp/Vs separating the Main Field from the East Flank. Detailed analyses of spatial and temporal variations in earthquake relocations and cumulative seismic moment release in the East Flank reveal three regions with persistently high rates of seismic activity. Two of these regions exhibit sharp, stationary boundaries at the margins of the East Flank that likely represent barriers to fluid flow and advective heat transport. However, seismicity and moment release in a third region at the northern end of the East Flank spread over time to form an elongated NE to SW structure, roughly parallel both to an elongated cluster of seismicity at the southern end of the East Flank and to regional fault traces mapped at the surface. Our results indicate that high-precision relocations of micro-seismicity and simultaneous velocity inversions in conjunction with mapping of seismic moment release can provide useful insights into subsurface structural features and hydrologic compartmentalization within the Coso Geothermal Field.

New Criterion and Tool for Caltrans Seismic Hazard Characterization

NASA Astrophysics Data System (ADS)

Shantz, T.; Merriam, M.; Turner, L.; Chiou, B.; Liu, X.

2008-12-01

Caltrans recently adopted new procedures for the development of response spectra for structure design. These procedures incorporate both deterministic and probabilistic criteria. The Next Generation Attenuation (NGA) models (2008) are used for deterministic assessment (using a revised late-Quaternary age fault database), and the USGS 2008 5% in 50-year hazard maps are used for probabilistic assessment. A minimum deterministic spectrum based on a M6.5 earthquake at 12 km is also included. These spectra are enveloped and the largest values used. A new publicly available web-based design tool for calculating the design spectrum will be used for calculations. The tool is built on a Windows-Apache-MySQL-PHP (WAMP) platform and integrates GoogleMaps for increased flexibility in the tool's use. Links to Caltrans data such as pre-construction logs of test borings assist in the estimation of Vs30 values used in the new procedures. Basin effects based on new models developed for the CFM, for the San Francisco Bay area by the USGS, and by Thurber (2008) are also incorporated. It is anticipated that additional layers such as CGS Seismic Hazard Zone maps will be added in the future. Application of the new criterion will result in expected higher levels of ground motion at many bridges west of the Coast Ranges. In eastern California, use of the NGA relationships for strike-slip faulting (the dominant sense of motion in California) will often result in slightly lower expected values for bridges. The expected result is a more realistic prediction of ground motions at bridges, in keeping with those motions developed for other large-scale and important structures. The tool is based on a simplified fault map of California, so it will not be used for more detailed evaluations such as surface rupture determination. Announcements regarding tool availability (expected to be in early 2009) are at http://www.dot.ca.gov/research/index.htm

An integrated study of seismic anisotropy and the natural fracture system at the Conoco Borehole Test Facility, Kay County, Oklahoma

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

Queen, J.H.; Rizer, W.D.

1990-07-10

A significant body of published work has developed establishing fracture-related seismic anisotropy as an observable effect. To further the understanding of seismic birefringence techniques in characterizing natural fracture systems at depth, an integrated program of seismic and geologic measurements has been conducted at Conoco's Borehole Test Facility in Kay County, Oklahoma. Birefringence parameters inferred from the seismic data are consistent with a vertical fracture model of density 0.04 striking east-northeast. That direction is subparallel to a fracture set mapped both on the surface and from subsurface data, to the in situ maximum horizontal stress, and to the inferred microfabric.

Comparative analysis of geodynamic activity of the Caucasian and Eastern Mediterranean segments of the Alpine-Himalayan convergence zone

NASA Astrophysics Data System (ADS)

Chelidze, Tamaz; Eppelbaum, Lev

2013-04-01

The Alpine-Himalayan convergence zone (AHCZ) underwent recent transverse shortening under the effect of collisional compression. The process was accompanied by rotation of separate microplates. The Caucasian and Eastern Mediterranean regions are segments of the of the AHCZ and are characterized by intensive endogenous and exogenous geodynamic processes, which manifest themselves in occurrence of powerful (with magnitude of 8-9) earthquakes accompanied by development of secondary catastrophic processes. Large landslides, rock falls, avalanches, mud flows, etc. cause human deaths and great material losses. The development of the aforesaid endogenous processes is set forth by peculiarities of the deep structure of the region and an impact of deep geological processes. The Caucasus is divided into several main tectonic terranes: platform (sub-platform, quasi-platform) and fold-thrust units. Existing data enable to perform a division of the Caucasian region into two large-scale geological provinces: southern Tethyan and northern Tethyan located to the south of and to the north of the Lesser Caucasian ophiolite suture, respectively. The recent investigations show that the assessments of the seismic hazard in these regions are not quite correct - for example in the West Caucasus the seismic hazard can be significantly underestimated, which affects the corresponding risk assessments. Integrated analysis of gravity, magnetic, seismic and thermal data enables to refine the assessment of the seismic hazard of the region, taking into account real rates of the geodynamic movements. Important role play the last rheological constructions. According to Reilinger et al. (2006) tectonic scheme, the West flanking of the Arabian Plate manifests strike-slip motion, when the East Caucasian block is converging and shortening. The Eastern Mediterranean is a tectonically complex region located in the midst of the progressive Afro-Eurasian collision. The recent increasing geotectonic activity in this region highlights the need for combined analysis of seismo-neotectonic signatures. For this purpose, this article presents the key features of the tectonic zonation of the Eastern Mediterranean. Map of derivatives of the gravity field retracked from the Geosat satellite and novel map of the Moho discontinuity illustrate the most important tectonic features of the region. The Post-Jurassic map of the deformation of surface leveling reflects the modern tectonic stage of Eastern Mediterranean evolution. The developed tectono-geophysical zonation map integrates the potential geophysical field analysis and seismic section utilization, as well as tectonic-structural, paleogeographical and facial analyses. Tectonically the map agrees with the earlier model of continental accretion (Ben-Avraham and Ginzburg, 1990). Overlaying the seismicity map of the Eastern Mediterranean tectonic region (for the period between 1900 and 2012) on the tectonic zonation chart reveals the key features of the seismo-neotectonic pattern of the Eastern Mediterranean. The results have important implications for tectonic-seismological analysis in this region (Eppelbaum and Katz, 2012). A difference in the geotectonic patterns makes interesting comparison of geodynamic activity and seismic hazard of the Caucasian and Eastern Mediterranean segments of the AHCZ.

Geologic map of the Sauvie Island quadrangle, Multnomah and Columbia Counties, Oregon, and Clark County, Washington

USGS Publications Warehouse

Evarts, Russell C.; O'Connor, Jim; Cannon, Charles M.

2016-03-02

This map contributes to a U.S. Geological Survey program to improve the geologic database for the Portland region of the Pacific Northwest urban corridor. The map and ancillary data will support assessments of seismic risk, ground-failure hazards, and resource availability.

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

Doug Blankenship

ArcGIS Map Package with MT Station Locations, 2D Seismic Lines, Well data, Known Regional Hydrothermal Systems, Regional Historic Earthquake Seismicity, Regional Temperature Gradient Data, Regional Heat Flow Data, Regional Radiogenic Heat Production, Local Geology, Land Status, Cultural Data, 2m Temperature Probe Data, and Gravity Data. Also a detailed down-hole lithology notes are provided.

A successful development of subtle traps: Chihuido de la Sierra Negra, Neuquen Basin

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

Comeron, R.; Valenzuela, M.W.

1996-08-01

Using new traps search concepts in the Chihuido de la Sierra Negra oil field, it was possible to substantially increase production from 4400 bbl/day in 1984 to 125,000 bbl/day in 1995. Oil reserves are located within an 8000 ha area situated on the Chihuido de la Sierra Negra anticlinal flank. Success was achieved by using different techniques for subtle traps detection, namely seismic amplitude mapping, individualization of different production facies and its predictive mapping. This reduced the search and development toward low structural areas which had not been considered before. The production layers are formed by two lower Cretaceous eolianmore » sandstones called the Avile Member and the Troncoso Lower Member, with thicknesses ranging from 5 to 30 meters. 2D seismic made it possible to individualize the thickest sand areas, some of which turned out to be productive. Using 3D seismic, by means of azimuth and dip maps, fractured areas were detected where fault throws range from 5 to 10 meters. In many of these fractured zones, thin igneous intrusives are emplaced forming seals. Such determinations make it possible for different oil-water contacts and static pressures to be delimited. Due to the small fault throws, the different blocks could not be detected by conventional mapping methods. The delineation of the field compartmentalization becomes important in the waterflooding stage as well as for the detection of new traps in surrounding areas. The combination of seismic and stratigraphic methods made it possible to discover and develop Argentina`s main oil field.« less

How widespread is human-induced seismicity in the USA and Canada?

NASA Astrophysics Data System (ADS)

Van der Baan, M.

2017-12-01

There has been significant public and scientific interest in the observation of changed seismicity rates in North America since 2008, possibly due to human activities. Van der Baan and Calixto (2017) find that the seismicity rate in Oklahoma between 2008 and 2016 is strongly correlated to increased hydrocarbon production. The possibility of systematic correlations between increased hydrocarbon production and seismicity rates is a pertinent question since the USA became the world's largest hydrocarbon producer in 2013, surpassing both Saudi Arabia's oil production and Russia's dry gas production. In most areas increased production is due to systematic hydraulic fracturing which involves high-pressure, underground fluid injection. Increased hydrocarbon production also leads to increased salt-water production which is often disposed of underground. Increased underground fluid injection in general may cause increased seismicity rates due to facilitated slip on pre-existing faults. Contrary to Oklahoma, analysis of oil and gas production versus seismicity rates in six other States in the USA and three provinces in Canada finds no State/Province-wide correlation between increased seismicity and hydrocarbon production, despite 8-16 fold increases in production in some States (Van der Baan and Calixto, 2017). However, in various areas, seismicity rates have increased locally. A comparison with seismic hazard maps shows that human-induced seismicity is less likely in areas that have historically felt fewer earthquakes. The opposite is not necessarily true. ReferencesVan der Baan, M. and Calixto, F. J. (2017), Human-induced seismicity and large-scale hydrocarbon production in the USA and Canada. Geochem. Geophys. Geosyst., 18, doi:10.1002/2017GC006915 AcknowledgmentsThe author thanks Frank Calixto who co-authored the paper on which a large portion of this lecture is based, the sponsors of the Microseismic Industry Consortium for financial support, the SEG for funding and organizing the SEG 2017 Honorary Lecturer tour, North America, and the organizers of this session, sponsored by the AGU Near Surface Geophysics and Seismology Divisions, for inviting him to give this presentation.

Seismic hazard, risk, and design for South America

USGS Publications Warehouse

Petersen, Mark D.; Harmsen, Stephen; Jaiswal, Kishor; Rukstales, Kenneth S.; Luco, Nicolas; Haller, Kathleen; Mueller, Charles; Shumway, Allison

2018-01-01

We calculate seismic hazard, risk, and design criteria across South America using the latest data, models, and methods to support public officials, scientists, and engineers in earthquake risk mitigation efforts. Updated continental scale seismic hazard models are based on a new seismicity catalog, seismicity rate models, evaluation of earthquake sizes, fault geometry and rate parameters, and ground‐motion models. Resulting probabilistic seismic hazard maps show peak ground acceleration, modified Mercalli intensity, and spectral accelerations at 0.2 and 1 s periods for 2%, 10%, and 50% probabilities of exceedance in 50 yrs. Ground shaking soil amplification at each site is calculated by considering uniform soil that is applied in modern building codes or by applying site‐specific factors based on VS30">VS30 shear‐wave velocities determined through a simple topographic proxy technique. We use these hazard models in conjunction with the Prompt Assessment of Global Earthquakes for Response (PAGER) model to calculate economic and casualty risk. Risk is computed by incorporating the new hazard values amplified by soil, PAGER fragility/vulnerability equations, and LandScan 2012 estimates of population exposure. We also calculate building design values using the guidelines established in the building code provisions. Resulting hazard and associated risk is high along the northern and western coasts of South America, reaching damaging levels of ground shaking in Chile, western Argentina, western Bolivia, Peru, Ecuador, Colombia, Venezuela, and in localized areas distributed across the rest of the continent where historical earthquakes have occurred. Constructing buildings and other structures to account for strong shaking in these regions of high hazard and risk should mitigate losses and reduce casualties from effects of future earthquake strong ground shaking. National models should be developed by scientists and engineers in each country using the best available science.

Surface-Wave Relocation of Remote Continental Earthquakes

NASA Astrophysics Data System (ADS)

Kintner, J. A.; Ammon, C. J.; Cleveland, M.

2017-12-01

Accurate hypocenter locations are essential for seismic event analysis. Single-event location estimation methods provide relatively imprecise results in remote regions with few nearby seismic stations. Previous work has demonstrated that improved relative epicentroid precision in oceanic environments is obtainable using surface-wave cross correlation measurements. We use intermediate-period regional and teleseismic Rayleigh and Love waves to estimate relative epicentroid locations of moderately-sized seismic events in regions around Iran. Variations in faulting geometry, depth, and intermediate-period dispersion make surface-wave based event relocation challenging across this broad continental region. We compare and integrate surface-wave based relative locations with InSAR centroid location estimates. However, mapping an earthquake sequence mainshock to an InSAR fault deformation model centroid is not always a simple process, since the InSAR observations are sensitive to post-seismic deformation. We explore these ideas using earthquake sequences in western Iran. We also apply surface-wave relocation to smaller magnitude earthquakes (3.5 < M < 5.0). Inclusion of smaller-magnitude seismic events in a relocation effort requires a shift in bandwidth to shorter periods, which increases the sensitivity of relocations to surface-wave dispersion. Frequency-domain inter-event phase observations are used to understand the time-domain cross-correlation information, and to choose the appropriate band for applications using shorter periods. Over short inter-event distances, the changing group velocity does not strongly degrade the relative locations. For small-magnitude seismic events in continental regions, surface-wave relocation does not appear simple enough to allow broad routine application, but using this method to analyze individual earthquake sequences can provide valuable insight into earthquake and faulting processes.

Seismic risk assessment of Navarre (Northern Spain)

NASA Astrophysics Data System (ADS)

Gaspar-Escribano, J. M.; Rivas-Medina, A.; García Rodríguez, M. J.; Benito, B.; Tsige, M.; Martínez-Díaz, J. J.; Murphy, P.

2009-04-01

The RISNA project, financed by the Emergency Agency of Navarre (Northern Spain), aims at assessing the seismic risk of the entire region. The final goal of the project is the definition of emergency plans for future earthquakes. With this purpose, four main topics are covered: seismic hazard characterization, geotechnical classification, vulnerability assessment and damage estimation to structures and exposed population. A geographic information system is used to integrate, analyze and represent all information colleted in the different phases of the study. Expected ground motions on rock conditions with a 90% probability of non-exceedance in an exposure time of 50 years are determined following a Probabilistic Seismic Hazard Assessment (PSHA) methodology that includes a logic tree with different ground motion and source zoning models. As the region under study is located in the boundary between Spain and France, an effort is required to collect and homogenise seismological data from different national and regional agencies. A new homogenised seismic catalogue, merging data from Spanish, French, Catalonian and international agencies and establishing correlations between different magnitude scales, is developed. In addition, a new seismic zoning model focused on the study area is proposed. Results show that the highest ground motions on rock conditions are expected in the northeastern part of the region, decreasing southwards. Seismic hazard can be expressed as low-to-moderate. A geotechnical classification of the entire region is developed based on surface geology, available borehole data and morphotectonic constraints. Frequency-dependent amplification factors, consistent with code values, are proposed. The northern and southern parts of the region are characterized by stiff and soft soils respectively, being the softest soils located along river valleys. Seismic hazard maps including soil effects are obtained by applying these factors to the seismic hazard maps on rock conditions (for the same probability level). Again, the highest hazard is found in the northeastern part of the region. The lowest hazard is obtained along major river valleys The vulnerability assessment of the Navarra building stock is accomplished using as proxy a combination of building age, location, number of floors and the implantation of building codes. Field surveys help constraining the extent of traditional and technological construction types. The vulnerability characterization is carried out following three methods: European Macroseismic Scale (EMS 98), RISK UE vulnerability index and the capacity spectrum method implemented in Hazus. Vulnerability distribution maps for each Navarrean municipality are provided, adapted to the EMS98 vulnerability classes. The vulnerability of Navarre is medium to high, except for recent urban, highly populated developments. For each vulnerability class and expected ground motion, damage distribution is estimated by means of damage probability matrixes. Several damage indexes, embracing relative and absolute damage estimates, are used. Expected average damage is low. Whereas the largest amounts of damaged structures are found in big cities, the highest percentages are obtained in some muniucipalities of northeastern Navarre. Additionally, expected percentages and amounts of affected persons by earthquake damage are calculated for each municipality. Expected amounts of affected people are low, reflecting the low expected damage degree.

Geophysical Monitoring Methods Evaluation for the FutureGen 2.0 Project

DOE PAGES

Strickland, Chris E.; USA, Richland Washington; Vermeul, Vince R.; ...

2014-12-31

A comprehensive monitoring program will be needed in order to assess the effectiveness of carbon sequestration at the FutureGen 2.0 carbon capture and storage (CCS) field-site. Geophysical monitoring methods are sensitive to subsurface changes that result from injection of CO 2 and will be used for: (1) tracking the spatial extent of the free phase CO 2 plume, (2) monitoring advancement of the pressure front, (3) identifying or mapping areas where induced seismicity occurs, and (4) identifying and mapping regions of increased risk for brine or CO 2 leakage from the reservoir. Site-specific suitability and cost effectiveness were evaluated formore » a number of geophysical monitoring methods including: passive seismic monitoring, reflection seismic imaging, integrated surface deformation, time-lapse gravity, pulsed neutron capture logging, cross-borehole seismic, electrical resistivity tomography, magnetotellurics and controlled source electromagnetics. The results of this evaluation indicate that CO 2 injection monitoring using reflection seismic methods would likely be difficult at the FutureGen 2.0 site. Electrical methods also exhibited low sensitivity to the expected CO 2 saturation changes and would be affected by metallic infrastructure at the field site. Passive seismic, integrated surface deformation, time-lapse gravity, and pulsed neutron capture monitoring were selected for implementation as part of the FutureGen 2.0 storage site monitoring program.« less

Geophysical Monitoring Methods Evaluation for the FutureGen 2.0 Project

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

Strickland, Chris E.; USA, Richland Washington; Vermeul, Vince R.

A comprehensive monitoring program will be needed in order to assess the effectiveness of carbon sequestration at the FutureGen 2.0 carbon capture and storage (CCS) field-site. Geophysical monitoring methods are sensitive to subsurface changes that result from injection of CO 2 and will be used for: (1) tracking the spatial extent of the free phase CO 2 plume, (2) monitoring advancement of the pressure front, (3) identifying or mapping areas where induced seismicity occurs, and (4) identifying and mapping regions of increased risk for brine or CO 2 leakage from the reservoir. Site-specific suitability and cost effectiveness were evaluated formore » a number of geophysical monitoring methods including: passive seismic monitoring, reflection seismic imaging, integrated surface deformation, time-lapse gravity, pulsed neutron capture logging, cross-borehole seismic, electrical resistivity tomography, magnetotellurics and controlled source electromagnetics. The results of this evaluation indicate that CO 2 injection monitoring using reflection seismic methods would likely be difficult at the FutureGen 2.0 site. Electrical methods also exhibited low sensitivity to the expected CO 2 saturation changes and would be affected by metallic infrastructure at the field site. Passive seismic, integrated surface deformation, time-lapse gravity, and pulsed neutron capture monitoring were selected for implementation as part of the FutureGen 2.0 storage site monitoring program.« less

Application of seismic interpretation in the development of Jerneh Field, Malay Basin

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

Yusoff, Z.

1994-07-01

Development of the Jerneh gas field has been significantly aided by the use of 3-D and site survey seismic interpretations. The two aspects that have been of particular importance are identification of sea-floor and near-surface safety hazards for safe platform installation/development drilling and mapping of reservoirs/hydrocarbons within gas-productive sands of the Miocene groups B, D, and E. Choice of platform location as well as casing design require detailed analysis of sea-floor and near-surface safety hazards. At Jerneh, sea-floor pockmarks near-surface high amplitudes, distributary channels, and minor faults were recognized as potential operational safety hazards. The integration of conventional 3-D andmore » site survey seismic data enabled comprehensive understanding of the occurrence and distribution of potential hazards to platform installation and development well drilling. Three-dimensional seismic interpretation has been instrumental not only in the field structural definition but also in recognition of reservoir trends and hydrocarbon distribution. Additional gas reservoirs were identified by their DHI characteristics and subsequently confirmed by development wells. The innovative use of seismic attribute mapping techniques has been very important in defining both fluid and reservoir distribution in groups B and D. Integration of 3-D seismic data and well-log interpretations has helped in optimal field development, including the planning of well locations and drilling sequence.« less

New Perspectives on Active Tectonics: Observing Fault Motion, Mapping Earthquake Strain Fields, and Visualizing Seismic Events in Multiple Dimensions Using Satellite Imagery and Geophysical Data Base

NASA Technical Reports Server (NTRS)

Crippen, R.; Blom, R.

1994-01-01

By rapidly alternating displays of SPOT satellite images acquired on 27 July 1991 and 25 July 1992 we are able to see spatial details of terrain movements along fault breaks associated with the 28 June 1992 Landers, California earthquake that are virtually undetectable by any other means.

Neo-deterministic seismic hazard assessment in North Africa

NASA Astrophysics Data System (ADS)

Mourabit, T.; Abou Elenean, K. M.; Ayadi, A.; Benouar, D.; Ben Suleman, A.; Bezzeghoud, M.; Cheddadi, A.; Chourak, M.; ElGabry, M. N.; Harbi, A.; Hfaiedh, M.; Hussein, H. M.; Kacem, J.; Ksentini, A.; Jabour, N.; Magrin, A.; Maouche, S.; Meghraoui, M.; Ousadou, F.; Panza, G. F.; Peresan, A.; Romdhane, N.; Vaccari, F.; Zuccolo, E.

2014-04-01

North Africa is one of the most earthquake-prone areas of the Mediterranean. Many devastating earthquakes, some of them tsunami-triggering, inflicted heavy loss of life and considerable economic damage to the region. In order to mitigate the destructive impact of the earthquakes, the regional seismic hazard in North Africa is assessed using the neo-deterministic, multi-scenario methodology (NDSHA) based on the computation of synthetic seismograms, using the modal summation technique, at a regular grid of 0.2 × 0.2°. This is the first study aimed at producing NDSHA maps of North Africa including five countries: Morocco, Algeria, Tunisia, Libya, and Egypt. The key input data for the NDSHA algorithm are earthquake sources, seismotectonic zonation, and structural models. In the preparation of the input data, it has been really important to go beyond the national borders and to adopt a coherent strategy all over the area. Thanks to the collaborative efforts of the teams involved, it has been possible to properly merge the earthquake catalogues available for each country to define with homogeneous criteria the seismogenic zones, the characteristic focal mechanism associated with each of them, and the structural models used to model wave propagation from the sources to the sites. As a result, reliable seismic hazard maps are produced in terms of maximum displacement ( D max), maximum velocity ( V max), and design ground acceleration.

Estimation of earthquake effects associated with a great earthquake in the New Madrid seismic zone

USGS Publications Warehouse

Hopper, Margaret G.; Algermissen, Sylvester Theodore; Dobrovolny, Ernest E.

1983-01-01

Estimates have been made of the effects of a large Ms = 8.6, Io = XI earthquake hypothesed to occur anywhere in the New Madrid seismic zone. The estimates are based on the distributions of intensities associated with the earthquakes of 1811-12, 1843 and 1895 although the effects of other historical shocks are also considered. The resulting composite type intensity map for a maximum intensity XI is believed to represent the upper level of shaking likely to occur. Specific intensity maps have been developed for six cities near the epicentral region taking into account the most likely distribution of site response in each city. Intensities found are: IX for Carbondale, IL; VIII and IX for Evansville, IN; VI and VIII for Little Rock, AR; IX and X for Memphis, TN; VIII, IX, and X for Paducah, KY; and VIII and X for Poplar Bluff, MO. On a regional scale, intensities are found to attenuate from the New Madrid seismic zone most rapidly to the west and southwest sides of the zone, most slowly to the northwest along the Mississippi River, on the northeast along the Ohio River, and on the southeast toward Georgia and South Carolina. Intensities attenuate toward the north, east, and south in a more normal fashion. Known liquefaction effects are documented but much more research is needed to define the liquefaction potential.

Conceptual Model for Basement and Surface Structure Relationships in an Oblique Collision, Sawtooth Range, MT

NASA Astrophysics Data System (ADS)

Palu, J. M.; Burberry, C. M.

2014-12-01

The reactivation potential of pre-existing basement structures affects the geometry of subsequent deformation structures. A conceptual model depicting the results of these interactions can be applied to multiple fold-thrust systems and lead to valuable deformation predictions. These predictions include the potential for hydrocarbon traps or seismic risk in an actively deforming area. The Sawtooth Range, Montana, has been used as a study area. A model for the development of structures close to the Augusta Syncline in the Sawtooth Range is being developed using: 1) an ArcGIS map of the basement structures of the belt based on analysis of geophysical data indicating gravity anomalies and aeromagnetic lineations, seismic data indicating deformation structures, and well logs for establishing lithologies, previously collected by others and 2) an ArcGIS map of the surface deformation structures of the belt based on interpretation of remote sensing images and verification through the collection of surface field data indicating stress directions and age relationships, resulting in a conceptual model based on the understanding of the interaction of the two previous maps including statistical correlations of data and development of balanced cross-sections using Midland Valley's 2D/3D Move software. An analysis of the model will then indicate viable deformation paths where prominent basement structures influenced subsequently developed deformation structures and reactivated faults. Preliminary results indicate that the change in orientation of thrust faults observed in the Sawtooth Range, from a NNW-SSE orientation near the Gibson Reservoir to a WNW-ESE trend near Haystack Butte correlates with pre-existing deformation structures lying within the Great Falls Tectonic Zone. The Scapegoat-Bannatyne trend appears to be responsible for this orientation change and rather than being a single feature, may be composed of up to 4 NE-SW oriented basement strike-slip faults. This indicates that the pre-existing basement features have a profound effect on the geometry of the later deformation. This conceptual model can also be applied to other deformed belts to provide a prediction for the potential hydrocarbon trap locations of the belt as well as their seismic risk.

Preliminary Studies of the Structural Characteristics of the Lubao Fault using 2D High Resolution Shallow Seismic Reflection Profile

NASA Astrophysics Data System (ADS)

Bonus, A. A. B.; Lagmay, A. M. A.; Rodolfo, K. S.

2016-12-01

The Lubao fault, located in the province of Pampanga, Philippines, is part of the Bataan Volcanic Arc Complex (BVAC). Active faults within and around the BVAC include the East Zambales and Iba faults; according to the official active faults map of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) there are no other existing active faults in the area. The Lubao Fault distinctly separates wetlands to the northeast and dry alluvial plains to the northwest of Manila Bay. Long term subsidence and high sedimentation rates were observed in the fault and over the past 1.5 thousand years, the northeastern block has dropped 3.5 meters. Along the southwest flank of Mount Natib, tectonic structures were identified using surface mapping and remote sensing. The Persistent Scattering Interferometric Synthetic Aperture Radar (PSInSAR) data results of Eco et al. in 2015 shows uplifts and subsidence in the BVAC area delineating the Lubao Fault. A 480-meter seismic reflection line was laid down perpendicular to the fault with a recording system consisting of 48 channels of Geometrics geophones spaced 10 meters apart. Acquired data were processed using the standard seismic reflection processing sequence by Yilmaz 2001. This preliminary study produced a high resolution subsurface profile of the Lubao fault in the village of San Rafael, Lubao where it is well manifested. The velocity model integrated by stratigraphic data of drilled core shows subsurface lithology. The depth converted profile reveals clear structures and dipping segments which indicates a history of movement along the Lubao fault. Discontinuity of reflectors, either offsets or breaks, are considered structures along the subsurface of the study area. Additional structural mapping and seismic lines along the projected fault are planned in the future to further detail the characteristics of the Lubao Fault. The surface observations made by other researchers coupled with the subsurface seismic profile mapping of this study hopes to clearly delineate and characterize the Lubao Fault.

4-D crustal structure of the conterminous U.S.: Continental assembly, crustal growth, and deformation history from receiver functions, xenoliths, and structural mapping

NASA Astrophysics Data System (ADS)

Schulte-Pelkum, V.; Mahan, K. H.

2015-12-01

We investigate seismic and geological features related to the tectonic evolution of the crust on a continent-wide scale. We present continent-wide features using Transportable Array data receiver function analysis, followed by regional comparisons to tie to ground truth from xenolith studies and structural mapping. We stress that the Transportable Array, at ~75 km station spacing, only offers a collection of point measurements of the crust due to the lack of crossing raypaths. 7.x layers (lower crust with high seismic velocities) can be created during crustal growth processes such as magmatic or mechanical underplating and during crustal modification such as large-scale melting. We present receiver function results and a compilation of previous regional studies using refraction data or receiver functions from regional dense networks. 7.x layers appear predominantly in parts of the northern U.S. Cordillera and across the southeastern U.S. We compare the seismic results with a xenolith study in Montana that details incremental growth of the 7.x layer from the Archean on. Hydration of a granulitic lower crust can destroy the 7.x layer and has the potential to cause epirogenic uplift. We interpret the pattern seen across the Transportable Array in the light of this hypothesis. Ductile deformation of the deep crust generates shear fabrics that can be detected seismically. Receiver functions detect shear zones via contrasts in foliation to the surrounding material. We map foliation strikes and depths in the crust across the Transportable Array using azimuthal analysis of receiver functions. Strikes from receiver functions typically align with surface fault traces in tectonically active regions, with depths of the converters exceeding the brittle zone. We discuss continent-wide strikes mapped with receiver functions. Contrasting orientations of Proterozoic shear zones and pervasive surrounding foliations in basement exposures in Colorado are reflected in seismic results from the Transportable Array and CREST experiment.

Application of Geographic Information System (GIS) to Model the Hydrocarbon Migration: Case Study from North-East Malay Basin, Malaysia

NASA Astrophysics Data System (ADS)

Rudini; Nasir Matori, Abd; Talib, Jasmi Ab; Balogun, Abdul-Lateef

2018-03-01

The purpose of this study is to model the migration of hydrocarbon using Geographic Information System (GIS). Understanding hydrocarbon migration is important since it can mean the difference between success and failure in oil and gas exploration project. The hydrocarbon migration modeling using geophysical method is still not accurate due to the limitations of available data. In recent years, GIS has emerged as a powerful tool for subsurface mapping and analysis. Recent studies have been carried out about the abilities of GIS to model hydrocarbon migration. Recent advances in GIS support the establishment and monitoring of prediction hydrocarbon migration. The concept, model, and calculation are based on the current geological situation. The spatial data of hydrocarbon reservoirs is determined by its geometry of lithology and geophysical attributes. Top of Group E horizon of north-east Malay basin was selected as the study area due to the occurrence of hydrocarbon migration. Spatial data and attributes data such as seismic data, wells log data and lithology were acquired and processed. Digital Elevation Model (DEM) was constructed from the selected horizon as a result of seismic interpretation using the Petrel software. Furthermore, DEM was processed in ArcGIS as a base map to shown hydrocarbon migration in north-east Malay Basin. Finally, all the data layers were overlaid to produce a map of hydrocarbon migration. A good data was imported to verify the model is correct.

Terrain Classification of Aster gDEM for Seismic Microzonation of Port-Au Haiti, Using - and - Based Analytic Methods

NASA Astrophysics Data System (ADS)

Yong, A.; Hough, S. E.; Cox, B. R.; Rathje, E. M.; Bachhuber, J.; Hulslander, D.; Christiansen, L.; Abrams, M.

2010-12-01

The aftermath of the M7.0 Haiti earthquake of 12 January 2010 witnessed an impressive scientific response from the international community. In addition to conventional post-earthquake investigations, there was also an unprecedented reliance on remote-sensing technologies for scientific investigation and damage assessment. These technologies include sensors from both aerial and space-borne observational platforms. As part of the Haiti earthquake response and recovery effort, we develop a seismic zonation map of Port-au-Prince based on high-resolution satellite imagery as well as data from traditional seismographic monitoring stations and geotechnical site characterizations. Our imagery consists of a global digital elevation model (gDEM) of Hispaniola derived from data recorded by NASA-JPL's Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument onboard the multi-platform satellite Terra. To develop our model we also consider recorded waveforms from portable seismographic stations (Hough et al., in review) and 36 geotechnical shear-wave velocity surveys (Cox et al., in review). Following a similar approach developed by Yong et al. (2008; Bull. Seism Soc. Am.), we use both pixel- and object- based imaging analytic methods to systematically identify and extract local terrain features that are expected to amplify seismic ground motion. Using histogram-stretching techniques applied to the rDEM values, followed by multi-resolution, segmentations of the imagery into terrain types, we systematically classify the terrains of Hispaniola. By associating available Vs30 (average shear-wave velocity in the upper 30 meter depth) calculated from the MASW (Multi-channel Analysis of Surface Wave) survey method, we develop a first-order site characterization map. Our results indicate that the terrain-based Vs30 estimates are significantly associated with amplitudes recorded at station sites. We also find that the damage distribution inferred from UNOSAT (UNITAR Operational Satellite Applications Program) data matches our estimates. However, the strongest amplifications are observed at two stations on a foothill ridge, where Vs30 values indicate that amplification should be relatively lower. Hough et al. (2010, this session) conclude that the observations can be explained by topographic amplification along a steep, narrow ridge. On the basis of these preliminary results, we conclude that the terrain-based framework, which characterizes topographic amplification as well as sediment-induced amplification, is needed to develop a microzonation map for Port-au-Prince.

Geopan AT@S: a Brokering Based Gateway to Georeferenced Historical Maps for Risk Analysis

NASA Astrophysics Data System (ADS)

Previtali, M.

2017-08-01

Importance of ancient and historical maps is nowadays recognized in many applications (e.g., urban planning, landscape valorisation and preservation, land changes identification, etc.). In the last years a great effort has been done by different institutions, such as Geographical Institutes, Public Administrations, and collaborative communities, for digitizing and publishing online collections of historical maps. In spite of this variety and availability of data, information overload makes difficult their discovery and management: without knowing the specific repository where the data are stored, it is difficult to find the information required. In addition, problems of interconnection between different data sources and their restricted interoperability may arise. This paper describe a new brokering based gateway developed to assure interoperability between data, in particular georeferenced historical maps and geographic data, gathered from different data providers, with various features and referring to different historical periods. The developed approach is exemplified by a new application named GeoPAN Atl@s that is aimed at linking in Northern Italy area land changes with risk analysis (local seismicity amplification and flooding risk) by using multi-temporal data sources and historic maps.

Are Eastern Basin (Ross Sea, Antarctica) Bathymetric Ridges Associated With the Last Glacial Maximum?

NASA Astrophysics Data System (ADS)

Chow, J. M.; Bart, P. J.

2005-05-01

Ross Sea (Antarctica) Eastern Basin bathymetric ridges have been interpreted to be ice stream divides created during the Last Glacial Maximum (LGM) advance of the Antarctic Ice Sheet based on radiocarbon dating of organic matter from near-seafloor sediments recovered in piston cores (Domack et al., 1999). Detailed seismic correlations and contour mapping show that there are at least five thick units outcropping in Eastern Basin. Four of these seismically-defined units can be correlated to age control at DSDP sites 270 and 272. In contrast to the near-seafloor sampling, the interiors of these units were initially assigned a Pliocene age based on a variety of microfossil biozones (Hayes and Frakes, 1975). Savage and Ciesielski (1983) determined that the youngest unit was deposited during the Coscinodiscus lentiginosus (since renamed Thalassiosira lentiginosa) diatom biozone (i.e., the unit formed sometime between 0.65 Ma to Recent timeframe). Thus, seafloor units in the area probably are of Quaternary age, but not necessarily LGM age. More recently, diatom biozonations for the Southern Ocean have been revised to provide more detailed biochronostratigraphic resolution (Zielinski and Gersonde, 2002; Zielinski et al., 2002). We are using the most recently-revised Southern Ocean diatom-zonation schemes to systematically evaluate ages of samples taken from the base of piston cores penetrating the five individual seismically-defined units in Eastern Basin. Using this sampling strategy, we increase the chances of penetrating through the Recent hemipelagic drape to sample the underlying seismically-defined units.

Earth-Shaking Seismology Activities for Middle School Classrooms

NASA Astrophysics Data System (ADS)

Braile, S. J.; Braile, L. W.

2004-12-01

A sequence of related earthquake and seismology activities provides an effective curriculum unit for inquiry-based science for the middle school level. The activities allow hands-on and in-depth study, progress from relatively simple "low-tech" approaches to more advanced activities emphasizing problem-solving and use of technology, and involve significant practice with science process skills. The unit begins with an earthquake plotting activity in which student teams find recent earthquake information from the Internet and plot epicenters on a classroom map. The activity continues throughout the year and provides opportunities for discovery, connections to other seismology activities, developing map skills, and cooperative learning. Subsequent activities include investigations of plate tectonics, plate boundaries, Earth's interior structure, seismic wave propagation, plotting earthquakes and volcanic eruptions on the computer using Alan Jones' Seismic/Eruption software, earthquake hazards, magnitude and intensity scales, and use of an educational seismograph in the classroom. The near real time monitoring of earthquakes provided by the mapping exercises and the educational seismograph, and the relevance of earthquake studies, generate student excitement and long term impact. We have shared this approach and the activities with K-12 teachers in many professional development settings. Many of the activities are available online at: www.eas.purdue.edu/~braile.

Gas Reservoir Identification Basing on Deep Learning of Seismic-print Characteristics

NASA Astrophysics Data System (ADS)

Cao, J.; Wu, S.; He, X.

2016-12-01

Reservoir identification based on seismic data analysis is the core task in oil and gas geophysical exploration. The essence of reservoir identification is to identify the properties of rock pore fluid. We developed a novel gas reservoir identification method named seismic-print analysis by imitation of the vocal-print analysis techniques in speaker identification. The term "seismic-print" is referred to the characteristics of the seismic waveform which can identify determinedly the property of the geological objectives, for instance, a nature gas reservoir. Seismic-print can be characterized by one or a few parameters named as seismic-print parameters. It has been proven that gas reservoirs are of characteristics of negative 1-order cepstrum coefficient anomaly and Positive 2-order cepstrum coefficient anomaly, concurrently. The method is valid for sandstone gas reservoir, carbonate reservoir and shale gas reservoirs, and the accuracy rate may reach up to 90%. There are two main problems to deal with in the application of seismic-print analysis method. One is to identify the "ripple" of a reservoir on the seismogram, and another is to construct the mapping relationship between the seismic-print and the gas reservoirs. Deep learning developed in recent years is of the ability to reveal the complex non-linear relationship between the attribute and the data, and of ability to extract automatically the features of the objective from the data. Thus, deep learning could been used to deal with these two problems. There are lots of algorithms to carry out deep learning. The algorithms can be roughly divided into two categories: Belief Networks Network (DBNs) and Convolutional Neural Network (CNN). DBNs is a probabilistic generative model, which can establish a joint distribution of the observed data and tags. CNN is a feedforward neural network, which can be used to extract the 2D structure feature of the input data. Both DBNs and CNN can be used to deal with seismic data. We use an improved DBNs to identify carbonate rocks from log data, the accuracy rate can reach up to 83%. DBNs is used to deal with seismic waveform data, more information is obtained. The work was supported by NSFC under grant No. 41430323 and No. 41274128, and State Key Lab. of Oil and Gas Reservoir Geology and Exploration.

Full-waveform seismic tomography of the Vrancea, Romania, subduction region

NASA Astrophysics Data System (ADS)

Baron, Julie; Morelli, Andrea

2017-12-01

The Vrancea region is one of the few locations of deep seismicity in Europe. Seismic tomography has been able to map lithospheric downwelling, but has not been able yet to clearly discriminate between competing geodynamic interpretations of the geological and geophysical evidence available. We study the seismic structure of the Vrancea subduction zone, using adjoint-based, full-waveform tomography to map the 3D vP and vS structure in detail. We use the database that was built during the CALIXTO (Carpathian Arc Lithosphere X-Tomography) temporary experiment, restricted to the broadband sensors and local intermediate-depth events. We fit waveforms with a cross-correlation misfit criterion in separate time windows around the expected P and S arrivals, and perform 17 iterations of vP and vS model updates (altogether, requiring about 16 million CPU hours) before reaching stable convergence. Among other features, our resulting model shows a nearly vertical, high-velocity body, that overlaps with the distribution of seismicity in its northeastern part. In its southwestern part, a slab appears to dip less steeply to the NW, and is suggestive of ongoing - or recently concluded - subduction geodynamic processes. Joint inversion for vP and vS allow us to address the vP/vS ratio distribution, that marks high vP/vS in the crust beneath the Focsani sedimentary basin - possibly due to high fluid pressure - and a low vP/vS edge along the lower plane of the subducting lithosphere, that in other similar environment has been attributed to dehydration of serpentine in the slab. In spite of the restricted amount of data available, and limitations on the usable frequency pass-band, full-waveform inversion reveals its potential to improve the general quality of imaging with respect to other tomographic techniques - although at a sensible cost in terms of computing resources. Our study also shows that re-analysis of legacy data sets with up-to-date techniques may bring new, useful, information.

A probabilistic estimate of maximum acceleration in rock in the contiguous United States

USGS Publications Warehouse

Algermissen, Sylvester Theodore; Perkins, David M.

1976-01-01

This paper presents a probabilistic estimate of the maximum ground acceleration to be expected from earthquakes occurring in the contiguous United States. It is based primarily upon the historic seismic record which ranges from very incomplete before 1930 to moderately complete after 1960. Geologic data, primarily distribution of faults, have been employed only to a minor extent, because most such data have not been interpreted yet with earthquake hazard evaluation in mind.The map provides a preliminary estimate of the relative hazard in various parts of the country. The report provides a method for evaluating the relative importance of the many parameters and assumptions in hazard analysis. The map and methods of evaluation described reflect the current state of understanding and are intended to be useful for engineering purposes in reducing the effects of earthquakes on buildings and other structures.Studies are underway on improved methods for evaluating the relativ( earthquake hazard of different regions. Comments on this paper are invited to help guide future research and revisions of the accompanying map.The earthquake hazard in the United States has been estimated in a variety of ways since the initial effort by Ulrich (see Roberts and Ulrich, 1950). In general, the earlier maps provided an estimate of the severity of ground shaking or damage but the frequency of occurrence of the shaking or damage was not given. Ulrich's map showed the distribution of expected damage in terms of no damage (zone 0), minor damage (zone 1), moderate damage (zone 2), and major damage (zone 3). The zones were not defined further and the frequency of occurrence of damage was not suggested. Richter (1959) and Algermissen (1969) estimated the ground motion in terms of maximum Modified Mercalli intensity. Richter used the terms "occasional" and "frequent" to characterize intensity IX shaking and Algermissen included recurrence curves for various parts of the country in the paper accompanying his map.The first probabilistic hazard maps covering portions of the United States were by Milne and Davenport (1969a). Recently, Wiggins, Hirshberg and Bronowicki (1974) prepared a probabilistic map of maximum particle velocity and Modified Mercalli intensity for the entire United States. The maps are based on an analysis of the historical seismicity. In general, geological data were not incorporated into the development of the maps.

New seismic study begins in Puerto Rico

USGS Publications Warehouse

Tarr, A.C.

1974-01-01

A new seismological project is now underway in Puerto Rico to provide information needed for accurate assessment of the island's seismic hazard. The project should also help to increase understanding of the tectonics and geologic evolution of the Caribbean region. The Puerto Rico Seismic Program is being conducted by the Geological Survey with support provided by the Puerto Rico Water Resources Authority, an agency responsible for generation and distribution of electric power throughout the Commonwealth. The Program will include the installation of a network of high quality seismograph stations to monitor seismic activity on and around Puerto Rico. These stations will be distributed across the island to record the seismicity as uniformly as possible. The detection and accurate location of small earthquakes, as well as moderate magnitude shocks, will aid in mapping active seismic zones and in compiling frequency of occurrence statistics which ultimately wil be useful in seismic risk-zoning of hte island. 

Static and Dynamic Reservoir Characterization Using High Resolution P-Wave Velocity Data in Delhi Field, la

NASA Astrophysics Data System (ADS)

Hussain, S.; Davis, T.

2012-12-01

Static and dynamic reservoir characterization was done on high resolution P-wave seismic data in Delhi Field, LA to study the complex stratigraphy of the Holt-Bryant sands and to delineate the CO2 flow path. The field is undergoing CO2 injection for enhanced oil recovery. The seismic data was bandwidth extended by Geotrace to decrease the tuning thickness effect. Once the authenticity of the added frequencies in the data was determined, the interpretation helped map thin Tuscaloosa and Paluxy sands. Cross-equalization was done on the baseline and monitor surveys to remove the non-repeatable noise in the data. Acoustic impedance (AI) inversion was done on the baseline and monitor surveys to map the changes in AI with CO2 injection in the field. Figure 1 shows the AI percentage change at Base Paluxy. The analysis helped identify areas that were not being swept by CO2. Figure 2 shows the CO2 flow paths in Tuscaloosa formation. The percentage change of AI with CO2 injection and pressure increase corresponded with the fluid substitution modeling results. Time-lapse interpretation helped in delineating the channels, high permeability zones and the bypassed zones in the reservoir.; Figure 1: P-impedance percentage difference map with a 2 ms window centered at the base of Paluxy with the production data from June 2010 overlain; the black dashed line is the oil-water contact; notice the negative impedance change below the OWC. The lighter yellow color shows area where Paluxy is not being swept completely. ; Figure 2: P-impedance percentage difference map at TUSC 7 top; the white triangles are TUSC 7 injectors and the white circles are TUSC 7 producers; the black polygons show the flow paths of CO2.

Three-dimensional geologic map of the Hayward fault, northern California: Correlation of rock unites with variations in seismicity, creep rate, and fault dip

USGS Publications Warehouse

Graymer, R.W.; Ponce, D.A.; Jachens, R.C.; Simpson, R.W.; Phelps, G.A.; Wentworth, C.M.

2005-01-01

In order to better understand mechanisms of active faults, we studied relationships between fault behavior and rock units along the Hayward fault using a three-dimensional geologic map. The three-dimensional map-constructed from hypocenters, potential field data, and surface map data-provided a geologic map of each fault surface, showing rock units on either side of the fault truncated by the fault. The two fault-surface maps were superimposed to create a rock-rock juxtaposition map. The three maps were compared with seismicity, including aseismic patches, surface creep, and fault dip along the fault, by using visuallization software to explore three-dimensional relationships. Fault behavior appears to be correlated to the fault-surface maps, but not to the rock-rock juxtaposition map, suggesting that properties of individual wall-rock units, including rock strength, play an important role in fault behavior. Although preliminary, these results suggest that any attempt to understand the detailed distribution of earthquakes or creep along a fault should include consideration of the rock types that abut the fault surface, including the incorporation of observations of physical properties of the rock bodies that intersect the fault at depth. ?? 2005 Geological Society of America.

A Fiber-Optic Borehole Seismic Vector Sensor System for Geothermal Site Characterization and Monitoring

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

Paulsson, Bjorn N.P.; Thornburg, Jon A.; He, Ruiqing

2015-04-21

Seismic techniques are the dominant geophysical techniques for the characterization of subsurface structures and stratigraphy. The seismic techniques also dominate the monitoring and mapping of reservoir injection and production processes. Borehole seismology, of all the seismic techniques, despite its current shortcomings, has been shown to provide the highest resolution characterization and most precise monitoring results because it generates higher signal to noise ratio and higher frequency data than surface seismic techniques. The operational environments for borehole seismic instruments are however much more demanding than for surface seismic instruments making both the instruments and the installation much more expensive. The currentmore » state-of-the-art borehole seismic instruments have not been robust enough for long term monitoring compounding the problems with expensive instruments and installations. Furthermore, they have also not been able to record the large bandwidth data available in boreholes or having the sensitivity allowing them to record small high frequency micro seismic events with high vector fidelity. To reliably achieve high resolution characterization and long term monitoring of Enhanced Geothermal Systems (EGS) sites a new generation of borehole seismic instruments must therefore be developed and deployed. To address the critical site characterization and monitoring needs for EGS programs, US Department of Energy (DOE) funded Paulsson, Inc. in 2010 to develop a fiber optic based ultra-large bandwidth clamped borehole seismic vector array capable of deploying up to one thousand 3C sensor pods suitable for deployment into ultra-high temperature and high pressure boreholes. Tests of the fiber optic seismic vector sensors developed on the DOE funding have shown that the new borehole seismic sensor technology is capable of generating outstanding high vector fidelity data with extremely large bandwidth: 0.01 – 6,000 Hz. Field tests have shown that the system can record events at magnitudes much smaller than M-2.6 at frequencies up to 2,000 Hz. The sensors have also proved to be about 100 times more sensitive than the regular coil geophones that are used in borehole seismic systems today. The fiber optic seismic sensors have furthermore been qualified to operate at temperatures over 300°C (572°F). Simultaneously with the fiber optic based seismic 3C vector sensors we are using the lead-in fiber to acquire Distributed Acoustic Sensor (DAS) data from the surface to the bottom of the vector array. While the DAS data is of much lower quality than the vector sensor data it provides a 1 m spatial sampling of the downgoing wavefield which will be used to build the high resolution velocity model which is an essential component in high resolution imaging and monitoring.« less

Location, structure, and seismicity of the Seattle fault zone, Washington: Evidence from aeromagnetic anomalies, geologic mapping, and seismic-reflection data

USGS Publications Warehouse

Blakely, R.J.; Wells, R.E.; Weaver, C.S.; Johnson, S.Y.

2002-01-01

A high-resolution aeromagnetic survey of the Puget Lowland shows details of the Seattle fault zone, an active but largely concealed east-trending zone of reverse faulting at the southern margin of the Seattle basin. Three elongate, east-trending magnetic anomalies are associated with north-dipping Tertiary strata exposed in the hanging wall; the magnetic anomalies indicate where these strata continue beneath glacial deposits. The northernmost anomaly, a narrow, elongate magnetic high, precisely correlates with magnetic Miocene volcanic conglomerate. The middle anomaly, a broad magnetic low, correlates with thick, nonmagnetic Eocene and Oligocene marine and fluvial strata. The southern anomaly, a broad, complex magnetic high, correlates with Eocene volcanic and sedimentary rocks. This tripartite package of anomalies is especially clear over Bainbridge Island west of Seattle and over the region east of Lake Washington. Although attenuated in the intervening region, the pattern can be correlated with the mapped strike of beds following a northwest-striking anticline beneath Seattle. The aeromagnetic and geologic data define three main strands of the Seattle fault zone identified in marine seismic-reflection profiles to be subparallel to mapped bedrock trends over a distance of >50 km. The locus of faulting coincides with a diffuse zone of shallow crustal seismicity and the region of uplift produced by the M 7 Seattle earthquake of A.D. 900-930.