Validation of simulated earthquake ground motions based on evolution of intensity and frequency content

USGS Publications Warehouse

Rezaeian, Sanaz; Zhong, Peng; Hartzell, Stephen; Zareian, Farzin

2015-01-01

Simulated earthquake ground motions can be used in many recent engineering applications that require time series as input excitations. However, applicability and validation of simulations are subjects of debate in the seismological and engineering communities. We propose a validation methodology at the waveform level and directly based on characteristics that are expected to influence most structural and geotechnical response parameters. In particular, three time-dependent validation metrics are used to evaluate the evolving intensity, frequency, and bandwidth of a waveform. These validation metrics capture nonstationarities in intensity and frequency content of waveforms, making them ideal to address nonlinear response of structural systems. A two-component error vector is proposed to quantify the average and shape differences between these validation metrics for a simulated and recorded ground-motion pair. Because these metrics are directly related to the waveform characteristics, they provide easily interpretable feedback to seismologists for modifying their ground-motion simulation models. To further simplify the use and interpretation of these metrics for engineers, it is shown how six scalar key parameters, including duration, intensity, and predominant frequency, can be extracted from the validation metrics. The proposed validation methodology is a step forward in paving the road for utilization of simulated ground motions in engineering practice and is demonstrated using examples of recorded and simulated ground motions from the 1994 Northridge, California, earthquake.

Ground Motion Characteristics of Induced Earthquakes in Central North America

NASA Astrophysics Data System (ADS)

Atkinson, G. M.; Assatourians, K.; Novakovic, M.

2017-12-01

The ground motion characteristics of induced earthquakes in central North America are investigated based on empirical analysis of a compiled database of 4,000,000 digital ground-motion records from events in induced-seismicity regions (especially Oklahoma). Ground-motion amplitudes are characterized non-parametrically by computing median amplitudes and their variability in magnitude-distance bins. We also use inversion techniques to solve for regional source, attenuation and site response effects. Ground motion models are used to interpret the observations and compare the source and attenuation attributes of induced earthquakes to those of their natural counterparts. Significant conclusions are that the stress parameter that controls the strength of high-frequency radiation is similar for induced earthquakes (depth of h 5 km) and shallow (h 5 km) natural earthquakes. By contrast, deeper natural earthquakes (h 10 km) have stronger high-frequency ground motions. At distances close to the epicenter, a greater focal depth (which increases distance from the hypocenter) counterbalances the effects of a larger stress parameter, resulting in motions of similar strength close to the epicenter, regardless of event depth. The felt effects of induced versus natural earthquakes are also investigated using USGS "Did You Feel It?" reports; 400,000 reports from natural events and 100,000 reports from induced events are considered. The felt reports confirm the trends that we expect based on ground-motion modeling, considering the offsetting effects of the stress parameter versus focal depth in controlling the strength of motions near the epicenter. Specifically, felt intensity for a given magnitude is similar near the epicenter, on average, for all event types and depths. At distances more than 10 km from the epicenter, deeper events are felt more strongly than shallow events. These ground-motion attributes imply that the induced-seismicity hazard is most critical for facilities in close proximity (<10 km) to oil and gas operations.

Near-Fault Strong Ground Motions during the 2016 Kumamoto, Japan, Earthquake

NASA Astrophysics Data System (ADS)

Iwata, T.; Asano, K.

2016-12-01

The 2016 Kumamoto mainshock (Mw7.0) produced a surface ruptured fault of about 20km long with maximum 2m offset, and identified as a surface ruptured event. Two strong motion records were observed near the surface ruptured fault at Mashiki town hall and Nishihara village hall. We investigated characteristics of those strong ground motions. As the acceleration records consisted of the baseline errors caused by nonzero initial acceleration and tilting of the accelerograph, we carefully removed the baseline errors (c.f. Chiu, 2001, Boore and Bommer, 2005) so as to obtain velocity and displacements. The observed permanent displacements were about 1.2m in horizontal direction and about 0.7m sinking in vertical direction at Mashiki town hall, and about 1.7m and 1.8m, respectively, at Nishihara village hall. Those permanent displacements almost coincide to results by GNSS and InSAR analysis (e.g., GSI, 2016). It takes about only 3 s to reach the permanent displacement. Somerville (2003) pointed out that ground motions from earthquakes producing large surface ruptures appeared to have systematically weaker ground motions than ground motions from earthquakes whose rupture were confined to the subsurface using the Ground Motion Prediction Equation (GMPE) for response spectra (Abrahamson and Silva, 1997). We calculated the response spectra of those records, compared them to the GMPE with the same manner and found two records were systematically larger than the expected from the GMPE in the period range of 0.3 s to 5 s. We need to re-consider the working hypothesis that the near-fault ground motions are weaker and to separate the near-fault and site effects on ground motions. Strong motions in the longer period range would be mainly caused by the near-fault (near-field term) effect.We used the acceleration data of the Kumamoto seismic intensity information network, provided by JMA.

Analysis of the ground motions from the MW 7.8 Gorkha and MW 7.3 Dolakha earthquakes in Nepal in 2015

NASA Astrophysics Data System (ADS)

Martin, S. S.; Hough, S. E.; Gahalaut, V. K.; Joshi, A.; Landes, M.; Bossu, R.

2016-12-01

While the 25 April 2015 MW7.8 Gorkha, Nepal, earthquake took a heavy toll in Nepal, damage and fatalities were lower than expected. There is thus an urgent need to understand ground motions from the mainshock and largest aftershock. We collected 3,831 accounts of macroseismic effects that include sufficient information to assign intensities. To assess intensities reliably, we apply EMS guidelines with an appreciation for issues associated with macroseismic effects of earthquakes in the Indian subcontinent. We as also analyze 21 available strong motion recordings. Available data are consistent with the peak ground acceleration (PGA) versus intensity relationship of Worden et al. (2012). We use this relationship to estimate peak ground acceleration (PGAEMS) from all intensities. For nearest-fault distances (RRUP<200km), PGAEMS is consistent with the Atkinson and Boore (2003) (AB03) subduction zone ground motion prediction equation (GMPE); at greater distances, instrumental PGA values are consistent with AB03, while PGAEMS is systematically higher. We use PGAEMS values within 200 km to investigate the variability of ground motions using the AB03 GMPE as a baseline. Across the near-field region, PGAEMS is higher by a factor of 2.0-2.5 towards the northern edge of the rupture compared to the near-field region nearer to the southern, up-dip edge of the rupture. Inferred de-amplification in the deepest part of the Kathmandu valley supports the conclusion that former lake-bed sediments experienced a pervasive non-linear response during the mainshock (Dixit et al., 2015). Ground motions were amplified in the southern Gangetic basin, but were relatively low in the northern basin. The overall distribution of ground motions and damage during the Gorkha earthquake thus reflects a combination of complex source, path, and site effects. We also analyze ground motions for the 12 May 2015 Dolakha aftershock, which we conclude was likely a high stress-drop event.

Empirical recurrence rates for ground motion signals on planetary surfaces

NASA Astrophysics Data System (ADS)

Lorenz, Ralph D.; Panning, Mark

2018-03-01

We determine the recurrence rates of ground motion events as a function of sensed velocity amplitude at several terrestrial locations, and make a first interplanetary comparison with measurements on the Moon, Mars, Venus and Titan. This empirical approach gives an intuitive order-of-magnitude guide to the observed ground motion (including both tectonic and ocean- and atmosphere-forced signals) of these locations as a guide to instrument expectations on future missions, without invoking interior models and specific sources: for example a Venera-14 observation of possible ground motion indicates a microseismic environment mid-way between noisy and quiet terrestrial locations. Quiet terrestrial regions see a peak velocity amplitude in mm/s roughly equal to 0.3*N(-0.7), where N is the number of "events" (half-hour intervals in which a given peak ground motion is exceeded) observed per year. The Apollo data show endogenous seismic signals for a given recurrence rate that are typically about 10,000 times smaller in amplitude than a quiet site on Earth, although local thermally-induced moonquakes are much more common. Viking data masked for low-wind periods appear comparable with a quiet terrestrial site, whereas a Venera observation of microseisms suggests ground motion more similar to a more active terrestrial location. Recurrence rate plots from in-situ measurements provide a context for seismic instrumentation on future planetary missions, e.g. to guide formulation of data compression schemes. While even small geophones can discriminate terrestrial activity rates, observations with guidance accelerometers are typically too insensitive to provide meaningful constraints (i.e. a non-zero number of "events") on actual ground motion observations unless operated for very long periods.

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.

Earthquake Early Warning in Japan - Result of recent two years -

NASA Astrophysics Data System (ADS)

Shimoyama, T.; Doi, K.; Kiyomoto, M.; Hoshiba, M.

2009-12-01

Japan Meteorological Agency(JMA) started to provide Earthquake Early Warning(EEW) to the general public in October 2007. It was followed by provision of EEW to a limited number of users who understand the technical limit of EEW and can utilize it for automatic control from August 2006. Earthquake Early Warning in Japan definitely means information of estimated amplitude and arrival time of a strong ground motion after fault rupture occurred. In other words, the EEW provided by JMA is defined as a forecast of a strong ground motion before the strong motion arrival. EEW of JMA is to enable advance countermeasures to disasters caused by strong ground motions with providing a warning message of anticipating strong ground motion before the S wave arrival. However, due to its very short available time period, there should need some measures and ideas to provide rapidly EEW and utilize it properly. - EEW is issued to general public when the maximum seismic intensity 5 lower (JMA scale) or greater is expected. - EEW message contains origin time, epicentral region name, and names of areas (unit is about 1/3 to 1/4 of one prefecture) where seismic intensity 4 or greater is expected. Expected arrival time is not included because it differs substantially even in one unit area. - EEW is to be broadcast through the broadcasting media(TV, radio and City Administrative Disaster Management Radio), and is delivered to cellular phones through cell broadcast system. For those who would like to know the more precise estimation and smaller earthquake information at their point of their properties, JMA allows designated private companies to provide forecast of strong ground motion, in which the estimation of a seismic intensity as well as arrival time of S-wave are contained, at arbitrary places under the JMA’s technical assurance. From October, 2007 to August, 2009, JMA issued 11 warnings to general public expecting seismic intensity “5 lower” or greater, including M=7.2 inland earthquake at Tohoku district (Iwate-Miyagi-nairiku-earthquakes; June 14, 2008) and M=6.5 earthquake at Suruga bay (August, 11, 2009). For 7 cases out of 11 cases seismic intensity “5 lower” or greater were actually observed; for 3 cases, observed maximum seismic intensity was 4; for 1 case it was false alarm. During this period, 10 earthquakes occurred for which observed maximum seismic intensity was “5 lower” or greater. For 7 cases out of 10, JMA issued the warnings to general public; for 3 cases the warnings were not issued because expected seismic intensity was 4. The false alarm, which occurred on 25, August, 2009 by software bag, raised discussion how the false warning should be canceled. In this study, we will summarize the performance of the system ,and introduce some examples of the actual issuance .

Application and API for Real-time Visualization of Ground-motions and Tsunami

NASA Astrophysics Data System (ADS)

Aoi, S.; Kunugi, T.; Suzuki, W.; Kubo, T.; Nakamura, H.; Azuma, H.; Fujiwara, H.

2015-12-01

Due to the recent progress of seismograph and communication environment, real-time and continuous ground-motion observation becomes technically and economically feasible. K-NET and KiK-net, which are nationwide strong motion networks operated by NIED, cover all Japan by about 1750 stations in total. More than half of the stations transmit the ground-motion indexes and/or waveform data in every second. Traditionally, strong-motion data were recorded by event-triggering based instruments with non-continues telephone line which is connected only after an earthquake. Though the data from such networks mainly contribute to preparations for future earthquakes, huge amount of real-time data from dense network are expected to directly contribute to the mitigation of ongoing earthquake disasters through, e.g., automatic shutdown plants and helping decision-making for initial response. By generating the distribution map of these indexes and uploading them to the website, we implemented the real-time ground motion monitoring system, Kyoshin (strong-motion in Japanese) monitor. This web service (www.kyoshin.bosai.go.jp) started in 2008 and anyone can grasp the current ground motions of Japan. Though this service provides only ground-motion map in GIF format, to take full advantage of real-time strong-motion data to mitigate the ongoing disasters, digital data are important. We have developed a WebAPI to provide real-time data and related information such as ground motions (5 km-mesh) and arrival times estimated from EEW (earthquake early warning). All response data from this WebAPI are in JSON format and are easy to parse. We also developed Kyoshin monitor application for smartphone, 'Kmoni view' using the API. In this application, ground motions estimated from EEW are overlapped on the map with the observed one-second-interval indexes. The application can playback previous earthquakes for demonstration or disaster drill. In mobile environment, data traffic and battery are limited and it is not practical to regularly visualize all the data. The application has automatic starting (pop-up) function triggered by EEW. Similar WebAPI and application for tsunami are being prepared using the pressure data recorded by dense offshore observation network (S-net), which is under construction along the Japan Trench.

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

Orientation-independent measures of ground motion

USGS Publications Warehouse

Boore, D.M.; Watson-Lamprey, Jennie; Abrahamson, N.A.

2006-01-01

The geometric mean of the response spectra for two orthogonal horizontal components of motion, commonly used as the response variable in predictions of strong ground motion, depends on the orientation of the sensors as installed in the field. This means that the measure of ground-motion intensity could differ for the same actual ground motion. This dependence on sensor orientation is most pronounced for strongly correlated motion (the extreme example being linearly polarized motion), such as often occurs at periods of 1 sec or longer. We propose two new measures of the geometric mean, GMRotDpp, and GMRotIpp, that are independent of the sensor orientations. Both are based on a set of geometric means computed from the as-recorded orthogonal horizontal motions rotated through all possible non-redundant rotation angles. GMRotDpp is determined as the ppth percentile of the set of geometric means for a given oscillator period. For example, GMRotDOO, GMRotD50, and GMRotD100 correspond to the minimum, median, and maximum values, respectively. The rotations that lead to GMRotDpp depend on period, whereas a single-period-independent rotation is used for GMRotIpp, the angle being chosen to minimize the spread of the rotation-dependent geometric mean (normalized by GMRotDpp) over the usable range of oscillator periods. GMRotI50 is the ground-motion intensity measure being used in the development of new ground-motion prediction equations by the Pacific Earthquake Engineering Center Next Generation Attenuation project. Comparisons with as-recorded geometric means for a large dataset show that the new measures are systematically larger than the geometric-mean response spectra using the as-recorded values of ground acceleration, but only by a small amount (less than 3%). The theoretical advantage of the new measures is that they remove sensor orientation as a contributor to aleatory uncertainty. Whether the reduction is of practical significance awaits detailed studies of large datasets. A preliminary analysis contained in a companion article by Beyer and Bommer finds that the reduction is small-to-nonexistent for equations based on a wide range of magnitudes and distances. The results of Beyer and Bommer do suggest, however, that there is an increasing reduction as period increases. Whether the reduction increases with other subdivisions of the dataset for which strongly correlated motions might be expected (e.g., pulselike motions close to faults) awaits further analysis.

Review: Progress in rotational ground-motion observations from explosions and local earthquakes in Taiwan

USGS Publications Warehouse

Lee, William H K.; Huang, Bor-Shouh; Langston, Charles A.; Lin, Chin-Jen; Liu, Chun-Chi; Shin, Tzay-Chyn; Teng, Ta-Liang; Wu, Chien-Fu

2009-01-01

Rotational motions generated by large earthquakes in the far field have been successfully measured, and observations agree well with the classical elasticity theory. However, recent rotational measurements in the near field of earthquakes in Japan and in Taiwan indicate that rotational ground motions are 10 to 100 times larger than expected from the classical elasticity theory. The near-field strong-motion records of the 1999 Mw 7.6 Chi-Chi, Taiwan, earthquake suggest that the ground motions along the 100 km rupture are complex. Some rather arbitrary baseline corrections are necessary in order to obtain reasonable displacement values from double integration of the acceleration data. Because rotational motions can contaminate acceleration observations due to the induced perturbation of the Earth’s gravitational field, we started a modest program to observe rotational ground motions in Taiwan.Three papers have reported the rotational observations in Taiwan: (1) at the HGSD station (Liu et al., 2009), (2) at the N3 site from two TAiwan Integrated GEodynamics Research (TAIGER) explosions (Lin et al., 2009), and (3) at the Taiwan campus of the National Chung-Cheng University (NCCU) (Wu et al., 2009). In addition, Langston et al. (2009) reported the results of analyzing the TAIGER explosion data. As noted by several authors before, we found a linear relationship between peak rotational rate (PRR in mrad/sec) and peak ground acceleration (PGA in m/sec2) from local earthquakes in Taiwan, PRR=0.002+1.301 PGA, with a correlation coefficient of 0.988.

Ground-motion variability resulting from the January 17, 1994, M = 6.6 Northridge earthquake at the interchange between highways 14 and I-5 in the northern San Fernando Valley

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

Hutchings, L.; Jarpe, S.; Kasameyer, P.

1994-02-04

Lawrence Livermore National Laboratory responded to the 17 January 1994, Northridge earthquake by sending an information gathering team to observe and study the collapse of the interchange between highways 14 and I-5 in the northern San Fernando Valley. This field team examined the structural failure at the interchange and the surface soil conditions, and they installed high-grain RefTek seismic recorders to record aftershocks. We recorded aftershocks for two weeks. Analyses of aftershock recordings in this report illustrate the degree of differential support motion for this site, and the higher than expected ground motion from an earthquake of this size andmore » distance. We used the aftershock recordings of small earthquakes as empirical Green`s functions and synthesized strong ground motion at three sites in the interchange area. Results presented here are based on an assumption that the geology of the interchange area remained linear in its response to the main event.« less

Ground Motion Prediction Trends For Eastern North America Based on the Next Generation Attenuation East Ground Motion Database

NASA Astrophysics Data System (ADS)

Cramer, C. H.; Kutliroff, J.; Dangkua, D.

2010-12-01

A five-year Next Generation Attenuation (NGA) East project to develop new ground motion prediction equations for stable continental regions (SCRs), including eastern North America (ENA), has begun at the Pacific Earthquake Engineering Research (PEER) Center funded by the Nuclear Regulatory Commission (NRC), the U.S. Geological Survey (USGS), the Electric Power Research Institute (EPRI), and the Department of Energy (DOE). The initial effort focused on database design and collection of appropriate M>4 ENA broadband and accelerograph records to populate the database. Ongoing work has focused on adding records from smaller ENA earthquakes and from other SCRs such as Europe, Australia, and India. Currently, over 6500 horizontal and vertical component records from 60 ENA earthquakes have been collected and prepared (instrument response removed, filtering to acceptable-signal band, determining peak and spectral parameter values, quality assurance, etc.) for the database. Geologic Survey of Canada (GSC) strong motion recordings, previously not available, have also been added to the NGA East database. The additional earthquakes increase the number of ground motion recordings in the 10 - 100 km range, particularly from the 2008 M5.2 Mt. Carmel, IL event, and the 2005 M4.7 Riviere du Loup and 2010 M5.0 Val des Bois earthquakes in Quebec, Canada. The goal is to complete the ENA database and make it available in 2011 followed by a SCR database in 2012. Comparisons of ground motion observations from four recent M5 ENA earthquakes with current ENA ground motion prediction equations (GMPEs) suggest that current GMPEs, as a group, reasonably agree with M5 observations at short periods, particularly at distances less than 200 km. However, at one second, current GMPEs over predict M5 ground motion observations. The 2001 M7.6 Bhuj, India, earthquake provides some constraint at large magnitudes, as geology and regional attenuation is analogous to ENA. Cramer and Kumar, 2003, have shown that ENA GMPE’s generally agree with the Bhuj dataset within 300 km at short and long periods. But the Bhuj earthquake does not exhibit the intermediate-period spectral sag (Atkinson, 1993) of larger ENA earthquakes and thus the Bhuj ground motions may be larger than what could be expected at one second for M7s in ENA.

The effect of sampling rate and anti-aliasing filters on high-frequency response spectra

USGS Publications Warehouse

Boore, David M.; Goulet, Christine

2013-01-01

The most commonly used intensity measure in ground-motion prediction equations is the pseudo-absolute response spectral acceleration (PSA), for response periods from 0.01 to 10 s (or frequencies from 0.1 to 100 Hz). PSAs are often derived from recorded ground motions, and these motions are usually filtered to remove high and low frequencies before the PSAs are computed. In this article we are only concerned with the removal of high frequencies. In modern digital recordings, this filtering corresponds at least to an anti-aliasing filter applied before conversion to digital values. Additional high-cut filtering is sometimes applied both to digital and to analog records to reduce high-frequency noise. Potential errors on the short-period (high-frequency) response spectral values are expected if the true ground motion has significant energy at frequencies above that of the anti-aliasing filter. This is especially important for areas where the instrumental sample rate and the associated anti-aliasing filter corner frequency (above which significant energy in the time series is removed) are low relative to the frequencies contained in the true ground motions. A ground-motion simulation study was conducted to investigate these effects and to develop guidance for defining the usable bandwidth for high-frequency PSA. The primary conclusion is that if the ratio of the maximum Fourier acceleration spectrum (FAS) to the FAS at a frequency fsaa corresponding to the start of the anti-aliasing filter is more than about 10, then PSA for frequencies above fsaa should be little affected by the recording process, because the ground-motion frequencies that control the response spectra will be less than fsaa . A second topic of this article concerns the resampling of the digital acceleration time series to a higher sample rate often used in the computation of short-period PSA. We confirm previous findings that sinc-function interpolation is preferred to the standard practice of using linear time interpolation for the resamplin

Preliminary SPE Phase II Far Field Ground Motion Estimates

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

Steedman, David W.

2014-03-06

Phase II of the Source Physics Experiment (SPE) program will be conducted in alluvium. Several candidate sites were identified. These include existing large diameter borehole U1e. One criterion for acceptance is expected far field ground motion. In June 2013 we were requested to estimate peak response 2 km from the borehole due to the largest planned SPE Phase II experiment: a contained 50- Ton event. The cube-root scaled range for this event is 5423 m/KT 1/3. The generally accepted first order estimate of ground motions from an explosive event is to refer to the standard data base for explosive eventsmore » (Perrett and Bass, 1975). This reference is a compilation and analysis of ground motion data from numerous nuclear and chemical explosive events from Nevada National Security Site (formerly the Nevada Test Site, or NTS) and other locations. The data were compiled and analyzed for various geologic settings including dry alluvium, which we believe is an accurate descriptor for the SPE Phase II setting. The Perrett and Bass plots of peak velocity and peak yield-scaled displacement, both vs. yield-scaled range, are provided here. Their analysis of both variables resulted in bi-linear fits: a close-in non-linear regime and a more distant linear regime.« less

Ground motion observations of the 2014 South Napa earthquake

USGS Publications Warehouse

Baltay, Annemarie S.; Boatwright, John

2015-01-01

Using the ground‐motion data compiled and reported by ShakeMap (Wald et al., 2000), we examine the peak ground acceleration (PGA) and peak ground velocity (PGV), as well as the pseudospectral acceleration (PSA) at periods of 0.3, 1.0, and 3.0 s. At the higher frequencies, especially PGA, data recorded at close distances (within ∼20  km) are very consistent with the GMPEs, implying a stress drop for this event similar to the median for California, that is, 5 MPa (Baltay and Hanks, 2014). At all frequencies, the attenuation with distance is stronger than the GMPEs would predict, which suggests the attenuation in the Napa and San Francisco Bay delta region is stronger than the average attenuation in California. The spatial plot of the ground‐motion residuals is positive to the north, in both Napa and Sonoma Valleys, consistent with increases in amplitude expected from both the directivity and basin effects. More interestingly, perhaps, there is strong ground motion to the south in the along‐strike direction, particularly for PSA at 1.0 s. These strongly positive residuals align with an older, Quaternary fault structure associated with the Franklin or Southampton fault, potentially indicating a fault‐zone‐guided wave.

NGA-West2 Empirical Fourier Model for Active Crustal Regions to Generate Regionally Adjustable Response Spectra

NASA Astrophysics Data System (ADS)

Bora, S. S.; Cotton, F.; Scherbaum, F.; Kuehn, N. M.

2016-12-01

Adjustment of median ground motion prediction equations (GMPEs) from data-rich (host) regions to data-poor regions (target) is one of major challenges that remains with the current practice of engineering seismology and seismic hazard analysis. Fourier spectral representation of ground motion provides a solution to address the problem of adjustment that is physically transparent and consistent with the concepts of linear system theory. Also, it provides a direct interface to appreciate the physically expected behavior of seismological parameters on ground motion. In the present study, we derive an empirical Fourier model for computing regionally adjustable response spectral ordinates based on random vibration theory (RVT) from shallow crustal earthquakes in active tectonic regions, following the approach of Bora et al. (2014, 2015). , For this purpose, we use an expanded NGA-West2 database with M 3.2—7.9 earthquakes at distances ranging from 0 to 300 km. A mixed-effects regression technique is employed to further explore various components of variability. The NGA-West2 database expanded over a wide magnitude range provides a better understanding (and constraint) of source scaling of ground motion. The large global volume of the database also allows investigating regional patterns in distance-dependent attenuation (i.e., geometrical spreading and inelastic attenuation) of ground motion as well as in the source parameters (e.g., magnitude and stress drop). Furthermore, event-wise variability and its correlation with stress parameter are investigated. Finally, application of the derived Fourier model in generating adjustable response spectra will be shown.

NASA ground-based and space-based laser ranging systems

NASA Technical Reports Server (NTRS)

Fitzmaurice, M. W.

1978-01-01

Laser ranging is expected to help unlock the mysteries of the earthquake phenomenon by producing unique results of crustal motions of the Earth. The current state of the art and future projections are presented, including principal applications and characteristics of typical systems.

Seismic-hazard maps and time histories for the commonwealth of Kentucky.

DOT National Transportation Integrated Search

2008-06-01

The ground-motion hazard maps and time histories for three earthquake scenarios, expected earthquakes, probable earthquakes, and maximum credible earthquakes on the free surface in hard rock (shear-wave velocity >1,500 m/s), were derived using the de...

Near-Fault Broadband Ground Motion Simulations Using Empirical Green's Functions: Application to the Upper Rhine Graben (France-Germany) Case Study

NASA Astrophysics Data System (ADS)

Del Gaudio, Sergio; Hok, Sebastien; Festa, Gaetano; Causse, Mathieu; Lancieri, Maria

2017-09-01

Seismic hazard estimation relies classically on data-based ground motion prediction equations (GMPEs) giving the expected motion level as a function of several parameters characterizing the source and the sites of interest. However, records of moderate to large earthquakes at short distances from the faults are still rare. For this reason, it is difficult to obtain a reliable ground motion prediction for such a class of events and distances where also the largest amount of damage is usually observed. A possible strategy to fill this lack of information is to generate synthetic accelerograms based on an accurate modeling of both extended fault rupture and wave propagation process. The development of such modeling strategies is essential for estimating seismic hazard close to faults in moderate seismic activity zones, where data are even scarcer. For that reason, we selected a target site in Upper Rhine Graben (URG), at the French-German border. URG is a region where faults producing micro-seismic activity are very close to the sites of interest (e.g., critical infrastructures like supply lines, nuclear power plants, etc.) needing a careful investigation of seismic hazard. In this work, we demonstrate the feasibility of performing near-fault broadband ground motion numerical simulations in a moderate seismic activity region such as URG and discuss some of the challenges related to such an application. The modeling strategy is to couple the multi-empirical Green's function technique (multi-EGFt) with a k -2 kinematic source model. One of the advantages of the multi-EGFt is that it does not require a detailed knowledge of the propagation medium since the records of small events are used as the medium transfer function, if, at the target site, records of small earthquakes located on the target fault are available. The selection of suitable events to be used as multi-EGF is detailed and discussed in our specific situation where less number of events are available. We then showed the impact that each source parameter characterizing the k-2 model has on ground motion amplitude. Finally we performed ground motion simulations showing results for different probable earthquake scenarios in the URG. Dependency of ground motions and of their variability are analyzed at different frequencies in respect of rupture velocity, roughness degree of slip distribution (stress drop), and hypocenter location. In near-source conditions, ground motion variability is shown to be mostly governed by the uncertainty on source parameters. In our specific configuration (magnitude, distance), the directivity effect is only observed in a limited frequency range. Rather, broadband ground motions are shown to be sensitive to both average rupture velocity and its possible variability, and to slip roughness. Ending up with a comparison of simulation results and GMPEs, we conclude that source parameters and their variability should be set up carefully to obtain reliable broadband ground motion estimations. In particular, our study shows that slip roughness should be set up in respect of the target stress drop. This entails the need for a better understanding of the physics of earthquake source and its incorporation in the ground motion modeling.

An extended stochastic method for seismic hazard estimation

NASA Astrophysics Data System (ADS)

Abd el-aal, A. K.; El-Eraki, M. A.; Mostafa, S. I.

2015-12-01

In this contribution, we developed an extended stochastic technique for seismic hazard assessment purposes. This technique depends on the hypothesis of stochastic technique of Boore (2003) "Simulation of ground motion using the stochastic method. Appl. Geophy. 160:635-676". The essential characteristics of extended stochastic technique are to obtain and simulate ground motion in order to minimize future earthquake consequences. The first step of this technique is defining the seismic sources which mostly affect the study area. Then, the maximum expected magnitude is defined for each of these seismic sources. It is followed by estimating the ground motion using an empirical attenuation relationship. Finally, the site amplification is implemented in calculating the peak ground acceleration (PGA) at each site of interest. We tested and applied this developed technique at Cairo, Suez, Port Said, Ismailia, Zagazig and Damietta cities to predict the ground motion. Also, it is applied at Cairo, Zagazig and Damietta cities to estimate the maximum peak ground acceleration at actual soil conditions. In addition, 0.5, 1, 5, 10 and 20 % damping median response spectra are estimated using the extended stochastic simulation technique. The calculated highest acceleration values at bedrock conditions are found at Suez city with a value of 44 cm s-2. However, these acceleration values decrease towards the north of the study area to reach 14.1 cm s-2 at Damietta city. This comes in agreement with the results of previous studies of seismic hazards in northern Egypt and is found to be comparable. This work can be used for seismic risk mitigation and earthquake engineering purposes.

Rupture process and strong ground motions of the 2007 Niigataken Chuetsu-Oki earthquake -Directivity pulses striking the Kashiwazaki-Kariwa Nuclear Power Plant-

NASA Astrophysics Data System (ADS)

Irikura, K.; Kagawa, T.; Miyakoshi, K.; Kurahashi, S.

2007-12-01

The Niigataken Chuetsu-Oki earthquake occurred on July 16, 2007, northwest-off Kashiwazaki in Niigata Prefecture, Japan, causing severe damages of ten people dead, about 1300 injured, about 1000 collapsed houses and major lifelines suspended. In particular, strong ground motions from the earthquake struck the Kashiwazaki-Kariwa nuclear power plant (hereafter KKNPP), triggering a fire at an electric transformer and other problems such as leakage of water containing radioactive materials into air and the sea, although the radioactivity levels of the releases are as low as those of the radiation which normal citizens would receive from the natural environment in a year. The source mechanism of this earthquake is a reverse fault, but whether it is the NE-SW strike and NW dip or the SW-NE strike and SE dip are still controversial from the aftershock distribution and geological surveys near the source. Results of the rupture processes inverted by using the GPS and SAR data, tsunami data and teleseismic data so far did not succeed in determining which fault planes moved. Strong ground motions were recorded at about 390 stations by the K-NET of NIED including the stations very close to the source area. There was the KKNPP which is probably one of buildings and facilities closest to the source area. They have their own strong motion network with 22 three-components' accelerographs locating at ground-surface, underground, buildings and basements of reactors. The PGA attenuation-distance relationships made setting the fault plane estimated from the GPS data generally follow the empirical relations in Japan, for example, Fukushima and Tanaka (1990) and Si and Midorikawa (1999), even if either fault plane, SE dip or NW dip, is assumed. However, the strong ground motions in the site of the KKNPP had very large accelerations and velocities more than those expected from the empirical relations. The surface motions there had the PGA of more than 1200 gals and even underground motions at the basements of the reactors locating five stories below the ground had the PGA of 680 gals. We simulated ground motions using the characterized source model (Kamae and Irikura, 1998) with three asperities and the empirical Green's function method (Irikura, 1986). Then, we found that the source model should be a reverse fault with the NE-SW strike and NW dip to explain the strong motion records obtained near the source area. In particular, strong ground motions in the site of the KKNPP had three significant pulses which are generated as directivity pulses in forward direction of rupture propagation. This is the reason why the strong ground motions in the site of the KKNPP had very large accelerations and velocities. The source model is also verified comparing the observed records at the KKNPP with the numerical simulations by the discrete wavenumber method (Bouchon, 1981).

Analytical and Experimental Research on Large Angle Maneuvers of Flexible Structures

DTIC Science & Technology

1990-05-04

and achieved a much higher level of technical maturity than could be expected based upon I the the proposal and contractual requirements. This...would expect , for example, that a very smooth, small reference torque input should result in the flexible structure motion approaching the rigid body...alleviated on sound physical grounds by using the forced response data (e. g., the frequency response function) to impose the proper scaling on the system

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

PEER Transportation Research Program | PEER Transportation Research Program

Science.gov Websites

methodologies, integrating fundamental knowledge, enabling technologies, and systems. We further expect that the Bayesian Framework for Performance Assessment and Risk Management of Transportation Systems subject to Earthquakes Directivity Modeling for NGA West2 Ground Motion Studies for Transportation Systems Performance

Vulnerability assessment of RC frames considering the characteristic of pulse-like ground motions

NASA Astrophysics Data System (ADS)

Xu, Chao; Wen, Zengping

2017-04-01

Pulse-like ground motions are a special class of ground motions that are particularly challenging to characterize for earthquake hazard assessment. These motions are characterized by a "pulse" in the velocity time history of the motion, and they are typically very intense and have been observed to cause severe damage to structures in past earthquakes. So it is particularly important to characterize these ground motions. Previous studies show that the severe response of structure is not entirely accounted for by measuring the intensity of the ground motion using spectral acceleration of the elastic first-mode period of a structure (Sa(T1)). This paper will use several alternative intensity measures to characterize the effect of pulse-like ground motions in vulnerability assessment. The ability of these intensity measures to characterize pulse-like ground motions will be evaluated. Pulse-like ground motions and ordinary ground motions are selected as input to carry out incremental dynamic analysis. Structural response and vulnerability are estimated by using Sa(T1) as the intensity measure. The impact of pulse period on structural response is studied through residual analysis. By comparing the difference between the structural response and vulnerability curves using pulse-like ground motions and ordinary ground motions as the input, the impact of velocity pulse on vulnerability is investigated and the shortcoming of using Sa(T1) to characterize pulse-like ground motion is analyzed. Then, vector-valued ground motion intensity measures(Sa(T1)&RT1,T2, Sa(T1)&RPGV,Sa) and inelastic displacement spectra(Sdi(T1)) are used to characterize the damage potential of pulse-like ground motions, the efficiency and sufficiency of these intensity measures are evaluated. The study shows that: have strong the damage potential of near fault ground motions with velocity pulse is closely related to the pulse period of strong motion as well as first mode period of vibration and nonlinear features of the structure. The above factors should be taken into account when choosing a reasonable ground motion parameter to characterize the damage potential of pulse-like ground motions. Vulnerability curves based on Sa(T1) show obvious differences between using near fault ground motions and ordinary ground motions, as well as pulse-like ground motions with different pulse periods as the input. When using vector-valued intensity measures such as Sa(T1)&RT1,T2, Sa(T1)&RPGV,Sa and inelastic displacement spectra, the results of vulnerability analysis are roughly the same. These ground motion intensity measures are more efficient and sufficient to characterize the damage potential of near fault ground motions with velocity pulse.

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.

Strong-motion observations of the M 7.8 Gorkha, Nepal, earthquake sequence and development of the N-shake strong-motion network

USGS Publications Warehouse

Dixit, Amod; Ringler, Adam; Sumy, Danielle F.; Cochran, Elizabeth S.; Hough, Susan E.; Martin, Stacey; Gibbons, Steven; Luetgert, James H.; Galetzka, John; Shrestha, Surya; Rajaure, Sudhir; McNamara, Daniel E.

2015-01-01

We present and describe strong-motion data observations from the 2015 M 7.8 Gorkha, Nepal, earthquake sequence collected using existing and new Quake-Catcher Network (QCN) and U.S. Geological Survey NetQuakes sensors located in the Kathmandu Valley. A comparison of QCN data with waveforms recorded by a conventional strong-motion (NetQuakes) instrument validates the QCN data. We present preliminary analysis of spectral accelerations, and peak ground acceleration and velocity for earthquakes up to M 7.3 from the QCN stations, as well as preliminary analysis of the mainshock recording from the NetQuakes station. We show that mainshock peak accelerations were lower than expected and conclude the Kathmandu Valley experienced a pervasively nonlinear response during the mainshock. Phase picks from the QCN and NetQuakes data are also used to improve aftershock locations. This study confirms the utility of QCN instruments to contribute to ground-motion investigations and aftershock response in regions where conventional instrumentation and open-access seismic data are limited. Initial pilot installations of QCN instruments in 2014 are now being expanded to create the Nepal–Shaking Hazard Assessment for Kathmandu and its Environment (N-SHAKE) network.

Evaluation of Ground-Motion Modeling Techniques for Use in Global ShakeMap - A Critique of Instrumental Ground-Motion Prediction Equations, Peak Ground Motion to Macroseismic Intensity Conversions, and Macroseismic Intensity Predictions in Different Tectonic Settings

USGS Publications Warehouse

Allen, Trevor I.; Wald, David J.

2009-01-01

Regional differences in ground-motion attenuation have long been thought to add uncertainty in the prediction of ground motion. However, a growing body of evidence suggests that regional differences in ground-motion attenuation may not be as significant as previously thought and that the key differences between regions may be a consequence of limitations in ground-motion datasets over incomplete magnitude and distance ranges. Undoubtedly, regional differences in attenuation can exist owing to differences in crustal structure and tectonic setting, and these can contribute to differences in ground-motion attenuation at larger source-receiver distances. Herein, we examine the use of a variety of techniques for the prediction of several ground-motion metrics (peak ground acceleration and velocity, response spectral ordinates, and macroseismic intensity) and compare them against a global dataset of instrumental ground-motion recordings and intensity assignments. The primary goal of this study is to determine whether existing ground-motion prediction techniques are applicable for use in the U.S. Geological Survey's Global ShakeMap and Prompt Assessment of Global Earthquakes for Response (PAGER). We seek the most appropriate ground-motion predictive technique, or techniques, for each of the tectonic regimes considered: shallow active crust, subduction zone, and stable continental region.

Assessment of modal-pushover-based scaling procedure for nonlinear response history analysis of ordinary standard bridges

USGS Publications Warehouse

Kalkan, E.; Kwong, N.

2012-01-01

The earthquake engineering profession is increasingly utilizing nonlinear response history analyses (RHA) to evaluate seismic performance of existing structures and proposed designs of new structures. One of the main ingredients of nonlinear RHA is a set of ground motion records representing the expected hazard environment for the structure. When recorded motions do not exist (as is the case in the central United States) or when high-intensity records are needed (as is the case in San Francisco and Los Angeles), ground motions from other tectonically similar regions need to be selected and scaled. The modal-pushover-based scaling (MPS) procedure was recently developed to determine scale factors for a small number of records such that the scaled records provide accurate and efficient estimates of “true” median structural responses. The adjective “accurate” refers to the discrepancy between the benchmark responses and those computed from the MPS procedure. The adjective “efficient” refers to the record-to-record variability of responses. In this paper, the accuracy and efficiency of the MPS procedure are evaluated by applying it to four types of existing Ordinary Standard bridges typical of reinforced concrete bridge construction in California. These bridges are the single-bent overpass, multi-span bridge, curved bridge, and skew bridge. As compared with benchmark analyses of unscaled records using a larger catalog of ground motions, it is demonstrated that the MPS procedure provided an accurate estimate of the engineering demand parameters (EDPs) accompanied by significantly reduced record-to-record variability of the EDPs. Thus, it is a useful tool for scaling ground motions as input to nonlinear RHAs of Ordinary Standard bridges.

Documentation for assessment of modal pushover-based scaling procedure for nonlinear response history analysis of "ordinary standard" bridges

USGS Publications Warehouse

Kalkan, Erol; Kwong, Neal S.

2010-01-01

The earthquake engineering profession is increasingly utilizing nonlinear response history analyses (RHA) to evaluate seismic performance of existing structures and proposed designs of new structures. One of the main ingredients of nonlinear RHA is a set of ground-motion records representing the expected hazard environment for the structure. When recorded motions do not exist (as is the case for the central United States), or when high-intensity records are needed (as is the case for San Francisco and Los Angeles), ground motions from other tectonically similar regions need to be selected and scaled. The modal-pushover-based scaling (MPS) procedure recently was developed to determine scale factors for a small number of records, such that the scaled records provide accurate and efficient estimates of 'true' median structural responses. The adjective 'accurate' refers to the discrepancy between the benchmark responses and those computed from the MPS procedure. The adjective 'efficient' refers to the record-to-record variability of responses. Herein, the accuracy and efficiency of the MPS procedure are evaluated by applying it to four types of existing 'ordinary standard' bridges typical of reinforced-concrete bridge construction in California. These bridges are the single-bent overpass, multi span bridge, curved-bridge, and skew-bridge. As compared to benchmark analyses of unscaled records using a larger catalog of ground motions, it is demonstrated that the MPS procedure provided an accurate estimate of the engineering demand parameters (EDPs) accompanied by significantly reduced record-to-record variability of the responses. Thus, the MPS procedure is a useful tool for scaling ground motions as input to nonlinear RHAs of 'ordinary standard' bridges.

Astrometric surveys in the Gaia era

NASA Astrophysics Data System (ADS)

Zacharias, Norbert

2018-04-01

The Gaia first data release (DR1) already provides an almost error free optical reference frame on the milli-arcsecond (mas) level allowing significantly better calibration of ground-based astrometric data than ever before. Gaia DR1 provides positions, proper motions and trigonometric parallaxes for just over 2 million stars in the Tycho-2 catalog. For over 1.1 billion additional stars DR1 gives positions. Proper motions for these, mainly fainter stars (G >= 11.5) are currently provided by several new projects which combine earlier epoch ground-based observations with Gaia DR1 positions. These data are very helpful in the interim period but will become obsolete with the second Gaia data release (DR2) expected in April 2018. The era of traditional, ground-based, wide-field astrometry with the goal to provide accurate reference stars has come to an end. Future ground-based astrometry will fill in some gaps (very bright stars, observations needed at many or specific epochs) and mainly will go fainter than the Gaia limit, like the PanSTARRS and the upcoming LSST surveys.

Seismology and Earthquake Ground Motions of the August 24, 2014 M6 South Napa Earthquake

NASA Astrophysics Data System (ADS)

Kishida, T.; Wang, S.; Mazzoni, S.; Markam, C.; Lu, Y.; Bozorgnia, Y.; Mahin, S.; Bray, J.; Panagiotou, M.; Stewart, J. P.; Darragh, R. B.; Abrahamson, N. A.; Hollenback, J. C.; Gutierrez, C.; Chiou, B.; Muin, S.; Dreger, D. S.

2014-12-01

The M6.0 South Napa earthquake produced strong ground motions in the northern San Francisco Bay area. A total of 214 three-component uncorrected digital accelerograms were downloaded from the CESMD website and processed following the PEER standard procedure (Ancheta et al. 2014). Intense ground motions were recorded in the heavily damaged area of Napa with peak acceleration greater than 0.3 g. Pulse-like waveforms were observed in several of the velocity time series at the near-fault stations. Near-fault velocity time series were rotated into fault normal and fault parallel directions and then characterized as pulse-like or non pulse-like according to previous studies by Hayden et al. (2014), Shahi (2013), and Lu and Panagiotou (2014). The near-fault velocity time series at five stations contained pulses with periods within the expected range of 0.7 s to 2.0 s for soil sites (Bray et al. 2009). However, they also contained longer period pulses than the expected range. High-frequency spikes were recorded at Carquinez Bridge Geotechnical Array #1 (CBGA1) of approximately 1.0 g on the NS component. These spikes were in the S-wave portion and were consistently observed in the downhole arrays and several other sites along the same azimuth from the source. The spikes increase in amplitude both from the Hwy 37/Napa River East Geotechnical Array to CBGA1 and from a depth below 100 m to the surface. This suggests that the spikes could be a result of path effects and site amplification through the surficial soft soil deposits. However, these observations do not exclude the possibility of soil-structure interaction effects on the measured recordings. The 5% damped pseudo-spectral accelerations (PSA) from the recorded ground motions compared well to those estimated from the recent NGA-West2 GMPEs. The exceptions are that PSA is under predicted from 1 to 3 seconds at several near fault records due to the velocity pulses and for short periods at Carquinez Bridge where the large high-frequency spikes in acceleration were recorded. The PSA of the recorded ground motions are compared to ASCE 7-10 design spectra and USGS uniform hazard spectra (UHS). The PSA exceeded the MCE spectra and the 2475-year UHS within the range of 1 to 2 s at two Napa stations, and short periods at CBGA1.

Real-time earthquake shake, damage, and loss mapping for Istanbul metropolitan area

NASA Astrophysics Data System (ADS)

Zülfikar, A. Can; Fercan, N. Özge Zülfikar; Tunç, Süleyman; Erdik, Mustafa

2017-01-01

The past devastating earthquakes in densely populated urban centers, such as the 1994 Northridge; 1995 Kobe; 1999 series of Kocaeli, Düzce, and Athens; and 2011 Van-Erciş events, showed that substantial social and economic losses can be expected. Previous studies indicate that inadequate emergency response can increase the number of casualties by a maximum factor of 10, which suggests the need for research on rapid earthquake shaking damage and loss estimation. The reduction in casualties in urban areas immediately following an earthquake can be improved if the location and severity of damages can be rapidly assessed by information from rapid response systems. In this context, a research project (TUBITAK-109M734) titled "Real-time Information of Earthquake Shaking, Damage, and Losses for Target Cities of Thessaloniki and Istanbul" was conducted during 2011-2014 to establish the rapid estimation of ground motion shaking and related earthquake damages and casualties for the target cities. In the present study, application to Istanbul metropolitan area is presented. In order to fulfill this objective, earthquake hazard and risk assessment methodology known as Earthquake Loss Estimation Routine, which was developed for the Euro-Mediterranean region within the Network of Research Infrastructures for European Seismology EC-FP6 project, was used. The current application to the Istanbul metropolitan area provides real-time ground motion information obtained by strong motion stations distributed throughout the densely populated areas of the city. According to this ground motion information, building damage estimation is computed by using grid-based building inventory, and the related loss is then estimated. Through this application, the rapidly estimated information enables public and private emergency management authorities to take action and allocate and prioritize resources to minimize the casualties in urban areas during immediate post-earthquake periods. Moreover, it is expected that during an earthquake, rapid information of ground shaking, damage, and loss estimations will provide vital information to allow appropriate emergency agencies to take immediate action, which will help to save lives. In general terms, this study can be considered as an example for application to metropolitan areas under seismic risk.

Local soil effects on the Ground Motion Prediction model for the Racha region in Georgia

NASA Astrophysics Data System (ADS)

Jorjiashvili, N.; Shengelia, I.; Otinashvili, M.; Tvaliashvili, A.

2016-12-01

The Caucasus is a region of numerous natural hazards and ensuing disasters. Analysis of the losses due to past disasters indicates those most catastrophic in the region have historically been due to strong earthquakes. Estimation of expected ground motion is a fundamental earthquake hazard assessment. The most commonly used parameter for attenuation relation is the peak ground acceleration because this parameter gives useful information for Seismic Hazard Assessment that was selected for the analysis. One of the most important topics that have a significant influence on earthquake records is the site ground conditions that are the main issue of the study because the same earthquake recorded at the same distance may cause different damage according to ground conditions. In the study earthquake records were selected for the Racha region in Georgia which has the highest seismic activity in the region. Next, new GMP models are obtained based on new digital data recorded in the same area. After removing the site effect the earthquake records on the rock site were obtained. Thus, two GMP models were obtained: one for the ground surface and the other for the rock site. At the end, comparison was done for the both models in order to analyze the influence of the local soil conditions on the GMP model.

Does amplitude scaling of ground motion records result in biased nonlinear structural drift responses?

USGS Publications Warehouse

Luco, N.; Bazzurro, P.

2007-01-01

Limitations of the existing earthquake ground motion database lead to scaling of records to obtain seismograms consistent with a ground motion target for structural design and evaluation. In the engineering seismology community, acceptable limits for 'legitimate' scaling vary from one (no scaling allowed) to 10 or more. The concerns expressed by detractors of scaling are mostly based on the knowledge of, for example, differences in ground motion characteristics for different earthquake magnitude-distance (Mw-Rclose) scenarios, and much less on their effects on structures. At the other end of the spectrum, proponents have demonstrated that scaling is not only legitimate but also useful for assessing structural response statistics for Mw-Rclose scenarios. Their studies, however, have not investigated more recent purposes of scaling and have not always drawn conclusions for a wide spectrum of structural vibration periods and strengths. This article investigates whether scaling of records randomly selected from an Mw-Rclose bin (or range) to a target fundamental-mode spectral acceleration (Sa) level introduces bias in the expected nonlinear structural drift response of both single-degree-of-freedom oscillators and one multi-degree-of-freedom building. The bias is quantified relative to unscaled records from the target Mw-Rclose bin that are 'naturally' at the target Sa level. We consider scaling of records from the target Mw-Rclose bin and from other Mw-Rclose bins. The results demonstrate that scaling can indeed introduce a bias that, for the most part, ca be explained by differences between the elastic response spectra of the scaled versus unscaled records. Copyright ?? 2007 John Wiley & Sons, Ltd.

Simulation of ground motion using the stochastic method

USGS Publications Warehouse

Boore, D.M.

2003-01-01

A simple and powerful method for simulating ground motions is to combine parametric or functional descriptions of the ground motion's amplitude spectrum with a random phase spectrum modified such that the motion is distributed over a duration related to the earthquake magnitude and to the distance from the source. This method of simulating ground motions often goes by the name "the stochastic method." It is particularly useful for simulating the higher-frequency ground motions of most interest to engineers (generally, f>0.1 Hz), and it is widely used to predict ground motions for regions of the world in which recordings of motion from potentially damaging earthquakes are not available. This simple method has been successful in matching a variety of ground-motion measures for earthquakes with seismic moments spanning more than 12 orders of magnitude and in diverse tectonic environments. One of the essential characteristics of the method is that it distills what is known about the various factors affecting ground motions (source, path, and site) into simple functional forms. This provides a means by which the results of the rigorous studies reported in other papers in this volume can be incorporated into practical predictions of ground motion.

Potential and Pitfalls of High-Rate GPS

NASA Astrophysics Data System (ADS)

Smalley, R.

2008-12-01

With completion of the Plate Boundary Observatory (PBO), we are poised to capture a dense sampling of strong motion displacement time series from significant earthquakes in western North America with High-Rate GPS (HRGPS) data collected at 1 and 5 Hz. These data will provide displacement time series at potentially zero epicentral distance that, if valid, have great potential to contribute to understanding earthquake rupture processes. The caveat relates to whether or not the data are aliased: is the sampling rate fast enough to accurately capture the displacement's temporal history? Using strong motion recordings in the immediate epicentral area of several 6.77.5 events, which can be reasonably expected in the PBO footprint, even the 5 Hz data may be aliased. Some sort of anti-alias processing, currently not applied, will therefore necessary at the closest stations to guarantee the veracity of the displacement time series. We discuss several solutions based on a-priori knowledge of the expected ground motion and practicality of implementation.

Strong ground motion in the Taipei basin from the 1999 Chi-Chi, Taiwan, earthquake

USGS Publications Warehouse

Fletcher, Joe B.; Wen, K.-L.

2005-01-01

The Taipei basin, located in northwest Taiwan about 160 km from the epicenter of the Chi-Chi earthquake, is a shallow, triangular-shaped basin filled with low-velocity fluvial deposits. There is a strong velocity contrast across the basement interface of about 600 m/sec at a depth of about 600-700 m in the deeper section of the basin, suggesting that ground motion should be amplified at sites in the basin. In this article, the ground-motion recordings are analyzed to determine the effect of the basin both in terms of amplifications expected from a 1D model of the sediments in the basin and in terms of the 3D structure of the basin. Residuals determined for peak acceleration from attenuation curves are more positive (amplified) in the basin (average of 5.3 cm/ sec2 compared to - 24.2 cm/sec2 for those stations outside the basin and between 75 and 110 km from the surface projection of the faulted area, a 40% increase in peak ground acceleration). Residuals for peak velocity are also significantly more positive at stations in the basin (31.8 cm/sec compared to 20.0 cm/sec out). The correlation of peak motion with depth to basement, while minor in peak acceleration, is stronger in the peak velocities. Record sections of ground motion from stations in and around the Taipei basin show that the largest long-period arrival, which is coherent across the region, is strongest on the vertical component and has a period of about 10-12 sec. This phase appears to be a Rayleigh wave, probably associated with rupture at the north end of the Chelungpu fault. Records of strong motion from stations in and near the basin have an additional, higher frequency signal: nearest the deepest point in the basin, the signal is characterized by frequencies of about 0.3 - 0.4 Hz. These frequencies are close to simple predictions using horizontal layers and the velocity structure of the basin. Polarizations of the S wave are mostly coherent across the array, although there are significant differences along the northwest edge that may indicate large strains across that edge of the basin. The length of each record after the main S wave are all longer at basin stations compared to those outside. This increase in duration of ground shaking is probably caused by amplification of ground motion at basin stations, although coda Q (0.67 - 1.30 Hz) is slightly larger inside the basin compared to those at local stations outside the basin. Durations correlate with depth to basement. These motions are in the range that can induce damage in buildings and may have contributed to the structural collapse of multistory buildings in the Taipei basin.

A New Distance Metric in Ground Motion Prediction Equations Based On Array Back-Projections

NASA Astrophysics Data System (ADS)

Feng, T.; Meng, L.

2017-12-01

Traditional Ground Motion Prediction Equations (GMPEs) measure the distances either relative to the epicenter (Repi) or the hypocenter (Rhyp) assuming point-sources, or relative to the closest point of the fault rupture (Rrup) or its surface projection (Rjb) to account for finite earthquake dimensions. However, it has long been proven that for large megathrust earthquakes (M>8), the over-simplification of the earthquake source characteristics in these distance metrics result in significant bias and uncertainty of the ground motion predictions. Recent advances in earthquake source imaging of major subduction earthquakes highlight the frequency-dependent and depth-varying seismic radiations at the plate interfaces. Low-frequency energy mainly emanated from the shallower portion of the megathrusts while dominant high-frequency energy often radiates from the deeper portion of the megathrust. In the 2011 Tohoku-Oki earthquake, all these distance metrics produce severe biases, underestimating the ground accelerations at short distances (<100km) and overestimating them at long distances (>100km). This phenomenon motivates an alternative distance metric based on the array back-projection (BP) technique that effectively captures regions releasing high-frequency energy. Herein, we define Rbp as the distance between nearest BP radiators and the station sites. We studied five large earthquakes in Japan, and found that Rbp outperforms conventional distance metrics in predicting the Psa (Pseudo Spectral Acceleration) in the high-frequency band (0.5-4 Hz). And at low frequencies (0.1-0.5Hz), we find that Rhyp produces better fits to the Psa spectrum. Thus, we propose to combine Rhyp and Rbp in low-frequency (0.1-0.5Hz) and high-frequency (0.5-4 Hz) range to improve the GMPEs. We consider that Rbp reflects the high-frequency characters of the rupture that are complementary to conventional GMPE distance metrics and a more suitable ground motion predictors in many cases. Based on our new distance metric, we expect to build an automatic system predicting ground motion immediately after the large earthquake (M>7) happens, an alternative to the shakemap.

Losses to single-family housing from ground motions in the 1994 Northridge, California, earthquake

USGS Publications Warehouse

Wesson, R.L.; Perkins, D.M.; Leyendecker, E.V.; Roth, R.J.; Petersen, M.D.

2004-01-01

The distributions of insured losses to single-family housing following the 1994 Northridge, California, earthquake for 234 ZIP codes can be satisfactorily modeled with gamma distributions. Regressions of the parameters in the gamma distribution on estimates of ground motion, derived from ShakeMap estimates or from interpolated observations, provide a basis for developing curves of conditional probability of loss given a ground motion. Comparison of the resulting estimates of aggregate loss with the actual aggregate loss gives satisfactory agreement for several different ground-motion parameters. Estimates of loss based on a deterministic spatial model of the earthquake ground motion, using standard attenuation relationships and NEHRP soil factors, give satisfactory results for some ground-motion parameters if the input ground motions are increased about one and one-half standard deviations above the median, reflecting the fact that the ground motions for the Northridge earthquake tended to be higher than the median ground motion for other earthquakes with similar magnitude. The results give promise for making estimates of insured losses to a similar building stock under future earthquake loading. ?? 2004, Earthquake Engineering Research Institute.

Rapid modeling of complex multi-fault ruptures with simplistic models from real-time GPS: Perspectives from the 2016 Mw 7.8 Kaikoura earthquake

NASA Astrophysics Data System (ADS)

Crowell, B.; Melgar, D.

2017-12-01

The 2016 Mw 7.8 Kaikoura earthquake is one of the most complex earthquakes in recent history, rupturing across at least 10 disparate faults with varying faulting styles, and exhibiting intricate surface deformation patterns. The complexity of this event has motivated the need for multidisciplinary geophysical studies to get at the underlying source physics to better inform earthquake hazards models in the future. However, events like Kaikoura beg the question of how well (or how poorly) such earthquakes can be modeled automatically in real-time and still satisfy the general public and emergency managers. To investigate this question, we perform a retrospective real-time GPS analysis of the Kaikoura earthquake with the G-FAST early warning module. We first perform simple point source models of the earthquake using peak ground displacement scaling and a coseismic offset based centroid moment tensor (CMT) inversion. We predict ground motions based on these point sources as well as simple finite faults determined from source scaling studies, and validate against true recordings of peak ground acceleration and velocity. Secondly, we perform a slip inversion based upon the CMT fault orientations and forward model near-field tsunami maximum expected wave heights to compare against available tide gauge records. We find remarkably good agreement between recorded and predicted ground motions when using a simple fault plane, with the majority of disagreement in ground motions being attributable to local site effects, not earthquake source complexity. Similarly, the near-field tsunami maximum amplitude predictions match tide gauge records well. We conclude that even though our models for the Kaikoura earthquake are devoid of rich source complexities, the CMT driven finite fault is a good enough "average" source and provides useful constraints for rapid forecasting of ground motion and near-field tsunami amplitudes.

A procedure to select ground-motion time histories for deterministic seismic hazard analysis from the Next Generation Attenuation (NGA) database

NASA Astrophysics Data System (ADS)

Huang, Duruo; Du, Wenqi; Zhu, Hong

2017-10-01

In performance-based seismic design, ground-motion time histories are needed for analyzing dynamic responses of nonlinear structural systems. However, the number of ground-motion data at design level is often limited. In order to analyze seismic performance of structures, ground-motion time histories need to be either selected from recorded strong-motion database or numerically simulated using stochastic approaches. In this paper, a detailed procedure to select proper acceleration time histories from the Next Generation Attenuation (NGA) database for several cities in Taiwan is presented. Target response spectra are initially determined based on a local ground-motion prediction equation under representative deterministic seismic hazard analyses. Then several suites of ground motions are selected for these cities using the Design Ground Motion Library (DGML), a recently proposed interactive ground-motion selection tool. The selected time histories are representatives of the regional seismic hazard and should be beneficial to earthquake studies when comprehensive seismic hazard assessments and site investigations are unavailable. Note that this method is also applicable to site-specific motion selections with the target spectra near the ground surface considering the site effect.

Seismic displacement of gently-sloping coastal and marine sediment under multidirectional earthquake loading

USGS Publications Warehouse

Kayen, Robert E.

2017-01-01

Gentle sediment-laden slopes are typical of the onshore coastal zone and offshore continental shelf and slope. Coastal sediment are commonly young weakly consolidated materials that are well stratified, have low strength, and can mobilize shear displacements at low levels of stress. Seismically-driven plastic displacements of these sediment pose a hazard to coastal cities, buried onshore utilities, and offshore infrastructure like harbor protection and outfalls. One-dimensional rigid downslope-directed Newmark sliding block analyses have been used to predict earthquake deformations generally on steeper slopes that are modeled as frictional materials. This study probes the effect of multidirectional earthquake motions on inertial displacements of gently sloping ground of the coastal and offshore condition where soft-compliant soil is expected. Toward that objective, this investigation seeks to understand the effect on Newmark-type displacements of [1] multidirectional earthquake shaking and [2] soil compliance. In order to model multidirectional effects, the earthquake motions are rotated into the local slope strike- and dip-components. On gently sloping ground, including the strike component of motion always results in a larger and more accurate shear stress vector. Strike motions are found to contribute to downslope deformations on any declivity. Compliant response of the soil mass also influences the plastic displacements. The magnitude of seismic displacements can be estimated with a simplified model using only the estimated soil yield-acceleration (ky) and the peak ground velocity (Vmax) of the earthquake motions. Compliance effects can be effectively mapped using the concept of Plastic Displacement Response Spectra (PDRS).

Ground Motion Prediction Equations Empowered by Stress Drop Measurement

NASA Astrophysics Data System (ADS)

Miyake, H.; Oth, A.

2015-12-01

Significant variation of stress drop is a crucial issue for ground motion prediction equations and probabilistic seismic hazard assessment, since only a few ground motion prediction equations take into account stress drop. In addition to average and sigma studies of stress drop and ground motion prediction equations (e.g., Cotton et al., 2013; Baltay and Hanks, 2014), we explore 1-to-1 relationship for each earthquake between stress drop and between-event residual of a ground motion prediction equation. We used the stress drop dataset of Oth (2013) for Japanese crustal earthquakes ranging 0.1 to 100 MPa and K-NET/KiK-net ground motion dataset against for several ground motion prediction equations with volcanic front treatment. Between-event residuals for ground accelerations and velocities are generally coincident with stress drop, as investigated by seismic intensity measures of Oth et al. (2015). Moreover, we found faster attenuation of ground acceleration and velocities for large stress drop events for the similar fault distance range and focal depth. It may suggest an alternative parameterization of stress drop to control attenuation distance rate for ground motion prediction equations. We also investigate 1-to-1 relationship and sigma for regional/national-scale stress drop variation and current national-scale ground motion equations.

Earthquake ground motion: Chapter 3

USGS Publications Warehouse

Luco, Nicolas; Kircher, Charles A.; Crouse, C. B.; Charney, Finley; Haselton, Curt B.; Baker, Jack W.; Zimmerman, Reid; Hooper, John D.; McVitty, William; Taylor, Andy

2016-01-01

Most of the effort in seismic design of buildings and other structures is focused on structural design. This chapter addresses another key aspect of the design process—characterization of earthquake ground motion into parameters for use in design. Section 3.1 describes the basis of the earthquake ground motion maps in the Provisions and in ASCE 7 (the Standard). Section 3.2 has examples for the determination of ground motion parameters and spectra for use in design. Section 3.3 describes site-specific ground motion requirements and provides example site-specific design and MCER response spectra and example values of site-specific ground motion parameters. Section 3.4 discusses and provides an example for the selection and scaling of ground motion records for use in various types of response history analysis permitted in the Standard.

Validating Pseudo-dynamic Source Models against Observed Ground Motion Data at the SCEC Broadband Platform, Ver 16.5

NASA Astrophysics Data System (ADS)

Song, S. G.

2016-12-01

Simulation-based ground motion prediction approaches have several benefits over empirical ground motion prediction equations (GMPEs). For instance, full 3-component waveforms can be produced and site-specific hazard analysis is also possible. However, it is important to validate them against observed ground motion data to confirm their efficiency and validity before practical uses. There have been community efforts for these purposes, which are supported by the Broadband Platform (BBP) project at the Southern California Earthquake Center (SCEC). In the simulation-based ground motion prediction approaches, it is a critical element to prepare a possible range of scenario rupture models. I developed a pseudo-dynamic source model for Mw 6.5-7.0 by analyzing a number of dynamic rupture models, based on 1-point and 2-point statistics of earthquake source parameters (Song et al. 2014; Song 2016). In this study, the developed pseudo-dynamic source models were tested against observed ground motion data at the SCEC BBP, Ver 16.5. The validation was performed at two stages. At the first stage, simulated ground motions were validated against observed ground motion data for past events such as the 1992 Landers and 1994 Northridge, California, earthquakes. At the second stage, they were validated against the latest version of empirical GMPEs, i.e., NGA-West2. The validation results show that the simulated ground motions produce ground motion intensities compatible with observed ground motion data at both stages. The compatibility of the pseudo-dynamic source models with the omega-square spectral decay and the standard deviation of the simulated ground motion intensities are also discussed in the study

Evaluation of Nevada Test Site Ground Motion and Rock Property Data to Bound Ground Motions at the Yucca Mountain Repository

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

Hutchings, L J; Foxall, W; Rambo, J

2005-02-14

Yucca Mountain licensing will require estimation of ground motions from probabilistic seismic hazard analyses (PSHA) with annual probabilities of exceedance on the order of 10{sup -6} to 10{sup -7} per year or smaller, which correspond to much longer earthquake return periods than most previous PSHA studies. These long return periods for the Yucca Mountain PSHA result in estimates of ground motion that are extremely high ({approx} 10 g) and that are believed to be physically unrealizable. However, there is at present no generally accepted method to bound ground motions either by showing that the physical properties of materials cannot maintainmore » such extreme motions, or the energy release by the source for such large motions is physically impossible. The purpose of this feasibility study is to examine recorded ground motion and rock property data from nuclear explosions to determine its usefulness for studying the ground motion from extreme earthquakes. The premise is that nuclear explosions are an extreme energy density source, and that the recorded ground motion will provide useful information about the limits of ground motion from extreme earthquakes. The data were categorized by the source and rock properties, and evaluated as to what extent non-linearity in the material has affected the recordings. They also compiled existing results of non-linear dynamic modeling of the explosions carried out by LLNL and other institutions. They conducted an extensive literature review to outline current understanding of extreme ground motion. They also analyzed the data in terms of estimating maximum ground motions at Yucca Mountain.« less

Evaluation of Nevada Test Site Ground Motion and Rock Property Data to Bound Ground Motions at the Yucca Mountain Repository

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

Hutchings, L H; Foxall, W; Rambo, J

2005-03-09

Yucca Mountain licensing will require estimation of ground motions from probabilistic seismic hazard analyses (PSHA) with annual probabilities of exceedance on the order of 10{sup -6} to 10{sup -7} per year or smaller, which correspond to much longer earthquake return periods than most previous PSHA studies. These long return periods for the Yucca Mountain PSHA result in estimates of ground motion that are extremely high ({approx} 10 g) and that are believed to be physically unrealizable. However, there is at present no generally accepted method to bound ground motions either by showing that the physical properties of materials cannot maintainmore » such extreme motions, or the energy release by the source for such large motions is physically impossible. The purpose of this feasibility study is to examine recorded ground motion and rock property data from nuclear explosions to determine its usefulness for studying the ground motion from extreme earthquakes. The premise is that nuclear explosions are an extreme energy density source, and that the recorded ground motion will provide useful information about the limits of ground motion from extreme earthquakes. The data were categorized by the source and rock properties, and evaluated as to what extent non-linearity in the material has affected the recordings. They also compiled existing results of non-linear dynamic modeling of the explosions carried out by LLNL and other institutions. They conducted an extensive literature review to outline current understanding of extreme ground motion. They also analyzed the data in terms of estimating maximum ground motions at Yucca Mountain.« less

Earthquake early warning using P-waves that appear after initial S-waves

NASA Astrophysics Data System (ADS)

Kodera, Y.

2017-12-01

As measures for underprediction for large earthquakes with finite faults and overprediction for multiple simultaneous earthquakes, Hoshiba (2013), Hoshiba and Aoki (2015), and Kodera et al. (2016) proposed earthquake early warning (EEW) methods that directly predict ground motion by computing the wave propagation of observed ground motion. These methods are expected to predict ground motion with a high accuracy even for complicated scenarios because these methods do not need source parameter estimation. On the other hand, there is room for improvement in their rapidity because they predict strong motion prediction mainly based on the observation of S-waves and do not explicitly use P-wave information available before the S-waves. In this research, we propose a real-time P-wave detector to incorporate P-wave information into these wavefield-estimation approaches. P-waves within a few seconds from the P-onsets are commonly used in many existing EEW methods. In addition, we focus on P-waves that may appear in the later part of seismic waves. Kurahashi and Irikura (2013) mentioned that P-waves radiated from strong motion generation areas (SMGAs) were recognizable after S-waves of the initial rupture point in the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0) (the Tohoku-oki earthquake). Detecting these P-waves would enhance the rapidity of prediction for the peak ground motion generated by SMGAs. We constructed a real-time P-wave detector that uses a polarity analysis. Using acceleration records in boreholes of KiK-net (band-pass filtered around 0.5-10 Hz with site amplification correction), the P-wave detector performed the principal component analysis with a sliding window of 4 s and calculated P-filter values (e.g. Ross and Ben-Zion, 2014). The application to the Tohoku-oki earthquake (Mw 9.0) showed that (1) peaks of P-filter that corresponded to SMGAs appeared in several stations located near SMGAs and (2) real-time seismic intensities (Kunugi et al., 2013) reached the local maximum several seconds after the P-filter peaks appeared. These findings indicate that the proposed P-wave detector allows wavefield-estimation approaches to predict the peak ground motion of SMGAs with a certain lead time.

Stochastic ground motion simulation

USGS Publications Warehouse

Rezaeian, Sanaz; Xiaodan, Sun; Beer, Michael; Kougioumtzoglou, Ioannis A.; Patelli, Edoardo; Siu-Kui Au, Ivan

2014-01-01

Strong earthquake ground motion records are fundamental in engineering applications. Ground motion time series are used in response-history dynamic analysis of structural or geotechnical systems. In such analysis, the validity of predicted responses depends on the validity of the input excitations. Ground motion records are also used to develop ground motion prediction equations(GMPEs) for intensity measures such as spectral accelerations that are used in response-spectrum dynamic analysis. Despite the thousands of available strong ground motion records, there remains a shortage of records for large-magnitude earthquakes at short distances or in specific regions, as well as records that sample specific combinations of source, path, and site characteristics.

Stress Drop and Depth Controls on Ground Motion From Induced Earthquakes

NASA Astrophysics Data System (ADS)

Baltay, A.; Rubinstein, J. L.; Terra, F. M.; Hanks, T. C.; Herrmann, R. B.

2015-12-01

Induced earthquakes in the central United States pose a risk to local populations, but there is not yet agreement on how to portray their hazard. A large source of uncertainty in the hazard arises from ground motion prediction, which depends on the magnitude and distance of the causative earthquake. However, ground motion models for induced earthquakes may be very different than models previously developed for either the eastern or western United States. A key question is whether ground motions from induced earthquakes are similar to those from natural earthquakes, yet there is little history of natural events in the same region with which to compare the induced ground motions. To address these problems, we explore how earthquake source properties, such as stress drop or depth, affect the recorded ground motion of induced earthquakes. Typically, due to stress drop increasing with depth, ground motion prediction equations model shallower events to have smaller ground motions, when considering the same absolute hypocentral distance to the station. Induced earthquakes tend to occur at shallower depths, with respect to natural eastern US earthquakes, and may also exhibit lower stress drops, which begs the question of how these two parameters interact to control ground motion. Can the ground motions of induced earthquakes simply be understood by scaling our known source-ground motion relations to account for the shallow depth or potentially smaller stress drops of these induced earthquakes, or is there an inherently different mechanism in play for these induced earthquakes? We study peak ground-motion velocity (PGV) and acceleration (PGA) from induced earthquakes in Oklahoma and Kansas, recorded by USGS networks at source-station distances of less than 20 km, in order to model the source effects. We compare these records to those in both the NGA-West2 database (primarily from California) as well as NGA-East, which covers the central and eastern United States and Canada. Preliminary analysis indicates that the induced ground motions appear similar to those from the NGA-West2 database. However, upon consideration of their shallower depths, ground motion behavior from induced events seems to fall in between the West data and that of NGA-East, so we explore the control of stress drop and depth on ground motion in more detail.

Determination of Paleoseismic Ground Motions from Inversion of Block Failures in Masonry Structures

NASA Astrophysics Data System (ADS)

Yagoda-Biran, G.; Hatzor, Y. H.

2010-12-01

Accurate estimation of ground motion parameters such as expected peak ground acceleration (PGA), predominant frequency and duration of motion in seismically active regions, is crucial for hazard preparedness and sound engineering design. The best way to estimate quantitatively these parameters would be to investigate long term recorded data of past strong earthquakes in a studied region. In some regions of the world however recorded data are scarce due to lack of seismic network infrastructure, and in all regions the availability of recorded data is restricted to the late 19th century and onwards. Therefore, existing instrumental data are hardly representative of the true seismicity of a region. When recorded data are scarce or not available, alternative methods may be applied, for example adopting a quantitative paleoseismic approach. In this research we suggest the use of seismically damaged masonry structures as paleoseismic indicators. Visitors to archeological sites all over the world are often struck by structural failure features which seem to be "seismically driven", particularly when inspecting old masonry structures. While it is widely accepted that no other loading mechanism can explain the preserved damage, the actual driving mechanism remains enigmatic even now. In this research we wish to explore how such failures may be triggered by earthquake induced ground motions and use observed block displacements to determine the characteristic parameters of the paleoseismic earthquake motion, namely duration, frequency, and amplitude. This is performed utilizing a 3D, fully dynamic, numerical analysis performed with the Discontinuous Deformation Analysis (DDA) method. Several case studies are selected for 3D numerical analysis. First we study a simple structure in the old city of L'Aquila, Italy. L'Aquila was hit by an earthquake on April 6th, 2009, with over 300 casualties and many of its medieval buildings damaged. This case study is an excellent opportunity to validate our method, since in the case of L'Aquila, both the damaged structure and the ground motions are recorded. The 3D modeling of the structure is rather complicated, and is performed by first modeling the structure with CAD software and later "translating" the model to the numerical code used. In the future, several more case studies will be analyzed, such as Kedesh and Avdat in Israel, and in collaboration with Hugh and Bilham the Temple of Shiva at Pandrethan, Kashmir. Establishing a numerical 3D dynamic analysis for back analysis of stone displacement in masonry structures as a paleoseismic tool can provide much needed data on ground motion parameters in regions where instrumental data are scarce, or are completely absent.

Micro-seismic measurements of cliff motion under wave impact and implications for the development of near-horizontal shore platforms

NASA Astrophysics Data System (ADS)

Dickson, Mark E.; Pentney, Rachael

2012-05-01

Few high-resolution measurements of process-form interactions have been taken on rock coasts, but recent studies in California have shown that portable seismometers enable useful proxy measurements of wave-energy delivery to cliffs. Here we describe measurements over 20 days of high frequency ground motion of cliffs formed in sedimentary (flysch) rocks at Okakari Point, north of Auckland, New Zealand. Three sensors were located in a shore-normal array inland from the cliff top and a fourth sensor was bolted to a ledge 2 m above the cliff toe. The nearshore wave field in front of the cliff and shore platform was monitored using a shore-normal array of 5 wave gauges. The instrumentation provided measurements of wave-energy delivery and consequent ground motion, including the first observations of motion at the top and bottom of cliffs. Results showed that horizontal ground motion is dominant at the cliff top, whereas vertical motion is dominant at the cliff toe. Power spectra show that several high frequency peaks occur in data from the cliff toe, whereas a single, broader peak frequency occurs at the cliff top resulting from signal modification as seismic waves pass through tens of metres of cliff rock. A 100 m wide shore platform at the cliff toe fundamentally controls the patterns of observed energy delivery. The shore platform is nearly horizontal, elevated close to high water level, and abruptly plunges into water > 10 m deep at its seaward edge. As expected, the magnitude of ground motion at all sensors is greatest during larger waves. Measurements further show that ground motion, both at the bottom and top of the cliff, is strongest at low tide and weakest at high tide. This observation is opposite to that noted at Santa Cruz, where ground motion was greatest at high tide. At Okakari Point the most significant high frequency ground motions occur at low tide when waves are forced to break (sometimes violently) against the seaward edge of the shore platform. Four distinctive frequency peaks between 1 and 50 Hz increase in magnitude as tidal stage drops, implying that wave breaking against the outside edge of the shore platform represents an important source of vibration. A detailed understanding of the energy source (e.g. short duration shock pressures) and rock resonance is not provided by this study. However, quantifying the spatial and temporal patterns of energy delivery places strong emphasis on the important role of shore platform geometry in filtering wave-energy delivery to the cliff. During the 20-day experiment most wave energy was delivered to the outside edge of the shore platform, not the cliff toe. The geomorphic role of high-frequency shaking from wave impacts remains to be clearly demonstrated, but if wave impacts are capable of eroding rock then the data from this study imply that under present conditions the outside edge of the shore platform may be subject to higher erosion rates than the cliff toe. It is possible that the shore platform is currently being destroyed rather than created, but a longer programme of measurements is required to test this notion.

Scaling earthquake ground motions for performance-based assessment of buildings

USGS Publications Warehouse

Huang, Y.-N.; Whittaker, A.S.; Luco, N.; Hamburger, R.O.

2011-01-01

The impact of alternate ground-motion scaling procedures on the distribution of displacement responses in simplified structural systems is investigated. Recommendations are provided for selecting and scaling ground motions for performance-based assessment of buildings. Four scaling methods are studied, namely, (1)geometric-mean scaling of pairs of ground motions, (2)spectrum matching of ground motions, (3)first-mode-period scaling to a target spectral acceleration, and (4)scaling of ground motions per the distribution of spectral demands. Data were developed by nonlinear response-history analysis of a large family of nonlinear single degree-of-freedom (SDOF) oscillators that could represent fixed-base and base-isolated structures. The advantages and disadvantages of each scaling method are discussed. The relationship between spectral shape and a ground-motion randomness parameter, is presented. A scaling procedure that explicitly considers spectral shape is proposed. ?? 2011 American Society of Civil Engineers.

Long-Period Ground Motion due to Near-Shear Earthquake Ruptures

NASA Astrophysics Data System (ADS)

Koketsu, K.; Yokota, Y.; Hikima, K.

2010-12-01

Long-period ground motion has become an increasingly important consideration because of the recent rapid increase in the number of large-scale structures, such as high-rise buildings and large oil storage tanks. Large subduction-zone earthquakes and moderate to large crustal earthquakes can generate far-source long-period ground motions in distant sedimentary basins with the help of path effects. Near-fault long-period ground motions are generated, for the most part, by the source effects of forward rupture directivity (Koketsu and Miyake, 2008). This rupture directivity effect is the maximum in the direction of fault rupture when a rupture velocity is nearly equal to shear wave velocity around a source fault (Dunham and Archuleta, 2005). The near-shear rupture was found to occur during the 2008 Mw 7.9 Wenchuan earthquake at the eastern edge of the Tibetan plateau (Koketsu et al., 2010). The variance of waveform residuals in a joint inversion of teleseismic and strong motion data was the minimum when we adopted a rupture velocity of 2.8 km/s, which is close to the shear wave velocity of 2.6 km/s around the hypocenter. We also found near-shear rupture during the 2010 Mw 6.9 Yushu earthquake (Yokota et al., 2010). The optimum rupture velocity for an inversion of teleseismic data is 3.5 km/s, which is almost equal to the shear wave velocity around the hypocenter. Since, in addition, supershear rupture was found during the 2001 Mw 7.8 Central Kunlun earthquake (Bouchon and Vallee, 2003), such fast earthquake rupture can be a characteristic of the eastern Tibetan plateau. Huge damage in Yingxiu and Beichuan from the 2008 Wenchuan earthquake and damage heavier than expected in the county seat of Yushu from the medium-sized Yushu earthquake can be attributed to the maximum rupture directivity effect in the rupture direction due to near-shear earthquake ruptures.

SMSIM--Fortran programs for simulating ground motions from earthquakes: Version 2.0.--a revision of OFR 96-80-A

USGS Publications Warehouse

Boore, David M.

2000-01-01

A simple and powerful method for simulating ground motions is based on the assumption that the amplitude of ground motion at a site can be specified in a deterministic way, with a random phase spectrum modified such that the motion is distributed over a duration related to the earthquake magnitude and to distance from the source. This method of simulating ground motions often goes by the name "the stochastic method." It is particularly useful for simulating the higher-frequency ground motions of most interest to engineers, and it is widely used to predict ground motions for regions of the world in which recordings of motion from damaging earthquakes are not available. This simple method has been successful in matching a variety of ground-motion measures for earthquakes with seismic moments spanning more than 12 orders of magnitude. One of the essential characteristics of the method is that it distills what is known about the various factors affecting ground motions (source, path, and site) into simple functional forms that can be used to predict ground motions. SMSIM is a set of programs for simulating ground motions based on the stochastic method. This Open-File Report is a revision of an earlier report (Boore, 1996) describing a set of programs for simulating ground motions from earthquakes. The programs are based on modifications I have made to the stochastic method first introduced by Hanks and McGuire (1981). The report contains source codes, written in Fortran, and executables that can be used on a PC. Programs are included both for time-domain and for random vibration simulations. In addition, programs are included to produce Fourier amplitude spectra for the models used in the simulations and to convert shear velocity vs. depth into frequency-dependent amplification. The revision to the previous report is needed because the input and output files have changed significantly, and a number of new programs have been included in the set.

A New Network-Based Approach for the Earthquake Early Warning

NASA Astrophysics Data System (ADS)

Alessandro, C.; Zollo, A.; Colombelli, S.; Elia, L.

2017-12-01

Here we propose a new method which allows for issuing an early warning based upon the real-time mapping of the Potential Damage Zone (PDZ), e.g. the epicentral area where the peak ground velocity is expected to exceed the damaging or strong shaking levels with no assumption about the earthquake rupture extent and spatial variability of ground motion. The system includes the techniques for a refined estimation of the main source parameters (earthquake location and magnitude) and for an accurate prediction of the expected ground shaking level. The system processes the 3-component, real-time ground acceleration and velocity data streams at each station. For stations providing high quality data, the characteristic P-wave period (τc) and the P-wave displacement, velocity and acceleration amplitudes (Pd, Pv and Pa) are jointly measured on a progressively expanded P-wave time window. The evolutionary estimate of these parameters at stations around the source allow to predict the geometry and extent of PDZ, but also of the lower shaking intensity regions at larger epicentral distances. This is done by correlating the measured P-wave amplitude with the Peak Ground Velocity (PGV) and Instrumental Intensity (IMM) and by interpolating the measured and predicted P-wave amplitude at a dense spatial grid, including the nodes of the accelerometer/velocimeter array deployed in the earthquake source area. Depending of the network density and spatial source coverage, this method naturally accounts for effects related to the earthquake rupture extent (e.g. source directivity) and spatial variability of strong ground motion related to crustal wave propagation and site amplification. We have tested this system by a retrospective analysis of three earthquakes: 2016 Italy 6.5 Mw, 2008 Iwate-Miyagi 6.9 Mw and 2011 Tohoku 9.0 Mw. Source parameters characterization are stable and reliable, also the intensity map shows extended source effects consistent with kinematic fracture models of evets.

Within-Event and Between-Events Ground Motion Variability from Earthquake Rupture Scenarios

NASA Astrophysics Data System (ADS)

Crempien, Jorge G. F.; Archuleta, Ralph J.

2017-09-01

Measurement of ground motion variability is essential to estimate seismic hazard. Over-estimation of variability can lead to extremely high annual hazard estimates of ground motion exceedance. We explore different parameters that affect the variability of ground motion such as the spatial correlations of kinematic rupture parameters on a finite fault and the corner frequency of the moment-rate spectra. To quantify the variability of ground motion, we simulate kinematic rupture scenarios on several vertical strike-slip faults and compute ground motion using the representation theorem. In particular, for the entire suite of rupture scenarios, we quantify the within-event and the between-events ground motion variability of peak ground acceleration (PGA) and response spectra at several periods, at 40 stations—all approximately at an equal distance of 20 and 50 km from the fault. Both within-event and between-events ground motion variability increase when the slip correlation length on the fault increases. The probability density functions of ground motion tend to truncate at a finite value when the correlation length of slip decreases on the fault, therefore, we do not observe any long-tail distribution of peak ground acceleration when performing several rupture simulations for small correlation lengths. Finally, for a correlation length of 6 km, the within-event and between-events PGA log-normal standard deviations are 0.58 and 0.19, respectively, values slightly smaller than those reported by Boore et al. (Earthq Spectra, 30(3):1057-1085, 2014). The between-events standard deviation is consistently smaller than the within-event for all correlations lengths, a feature that agrees with recent ground motion prediction equations.

Rotational motions from the 2016, Central Italy seismic sequence, as observed by an underground ring laser gyroscope

NASA Astrophysics Data System (ADS)

Simonelli, A.; Igel, H.; Wassermann, J.; Belfi, J.; Di Virgilio, A.; Beverini, N.; De Luca, G.; Saccorotti, G.

2018-05-01

We present the analysis of rotational and translational ground motions from earthquakes recorded during October/November, 2016, in association with the Central Italy seismic-sequence. We use co-located measurements of the vertical ground rotation rate from a large ring laser gyroscope (RLG), and the three components of ground velocity from a broadband seismometer. Both instruments are positioned in a deep underground environment, within the Gran Sasso National Laboratories (LNGS) of the Istituto Nazionale di Fisica Nucleare (INFN). We collected dozens of events spanning the 3.5-5.9 Magnitude range, and epicentral distances between 30 km and 70 km. This data set constitutes an unprecedented observation of the vertical rotational motions associated with an intense seismic sequence at local distance. Under the plane wave approximation we process the data set in order to get an experimental estimation of the events back azimuth. Peak values of rotation rate (PRR) and horizontal acceleration (PGA) are markedly correlated, according to a scaling constant which is consistent with previous measurements from different earthquake sequences. We used a prediction model in use for Italy to calculate the expected PGA at the recording site, obtaining consequently predictions for PRR. Within the modeling uncertainties, predicted rotations are consistent with the observed ones, suggesting the possibility of establishing specific attenuation models for ground rotations, like the scaling of peak velocity and peak acceleration in empirical ground-motion prediction relationships. In a second step, after identifying the direction of the incoming wave-field, we extract phase velocity data using the spectral ratio of the translational and rotational components.. This analysis is performed over time windows associated with the P-coda, S-coda and Lg phase. Results are consistent with independent estimates of shear-wave velocities in the shallow crust of the Central Apennines.

Application of constrained k-means clustering in ground motion simulation validation

NASA Astrophysics Data System (ADS)

Khoshnevis, N.; Taborda, R.

2017-12-01

The validation of ground motion synthetics has received increased attention over the last few years due to the advances in physics-based deterministic and hybrid simulation methods. Unlike for low frequency simulations (f ≤ 0.5 Hz), for which it has become reasonable to expect a good match between synthetics and data, in the case of high-frequency simulations (f ≥ 1 Hz) it is not possible to match results on a wiggle-by-wiggle basis. This is mostly due to the various complexities and uncertainties involved in earthquake ground motion modeling. Therefore, in order to compare synthetics with data we turn to different time series metrics, which are used as a means to characterize how the synthetics match the data on qualitative and statistical sense. In general, these metrics provide GOF scores that measure the level of similarity in the time and frequency domains. It is common for these scores to be scaled from 0 to 10, with 10 representing a perfect match. Although using individual metrics for particular applications is considered more adequate, there is no consensus or a unified method to classify the comparison between a set of synthetic and recorded seismograms when the various metrics offer different scores. We study the relationship among these metrics through a constrained k-means clustering approach. We define 4 hypothetical stations with scores 3, 5, 7, and 9 for all metrics. We put these stations in the category of cannot-link constraints. We generate the dataset through the validation of the results from a deterministic (physics-based) ground motion simulation for a moderate magnitude earthquake in the greater Los Angeles basin using three velocity models. The maximum frequency of the simulation is 4 Hz. The dataset involves over 300 stations and 11 metrics, or features, as they are understood in the clustering process, where the metrics form a multi-dimensional space. We address the high-dimensional feature effects with a subspace-clustering analysis, generate a final labeled dataset of stations, and discuss the within-class statistical characteristics of each metric. Labeling these stations is the first step towards developing a unified metric to evaluate ground motion simulations in an application-independent manner.

Earthquake ground motion simulation at Zoser pyramid using the stochastic method: A step toward the preservation of an ancient Egyptian heritage

NASA Astrophysics Data System (ADS)

Khalil, Amin E.; Abdel Hafiez, H. E.; Girgis, Milad; Taha, M. A.

2017-06-01

Strong ground shaking during earthquakes can greatly affect the ancient monuments and subsequently demolish the human heritage. On October 12th 1992, a moderate earthquake (Ms = 5.8) shocked the greater Cairo area causing widespread damages. Unfortunately, the focus of that earthquake is located about 14 km to the south of Zoser pyramid. After the earthquake, the Egyptian Supreme council of antiquities issued an alarm that Zoser pyramid is partially collapsed and international and national efforts are exerted to restore this important human heritage that was built about 4000 years ago. Engineering and geophysical work is thus needed for the restoration process. The definition of the strong motion parameters is one of the required studies since seismically active zone is recorded in its near vicinity. The present study adopted the stochastic method to determine the peak ground motion (acceleration, velocity and displacement) for the three largest earthquakes recorded in the Egypt's seismological history. These earthquakes are Shedwan earthquake with magnitude Ms = 6.9, Aqaba earthquake with magnitude Mw = 7.2 and Cairo (Dahshour earthquake) with magnitude Ms = 5.8. The former two major earthquakes took place few hundred kilometers away. It is logic to have the predominant effects from the epicentral location of the Cairo earthquake; however, the authors wanted to test also the long period effects of the large distance earthquakes expected from the other two earthquakes under consideration. In addition, the dynamic site response was studied using the Horizontal to vertical spectral ratio (HVSR) technique. HVSR can provide information about the fundamental frequency successfully; however, the amplification estimation is not accepted. The result represented as either peak ground motion parameters or response spectra indicates that the effects from Cairo earthquake epicenter are the largest for all periods considered in the present study. The level of strong motion as indicated by peak ground acceleration reaches the value of 250 gals which is considerably high. At the end, it is worth to mention that the information resulted from the present work may be useful for the planned restoration decision of the Zoser pyramid site.

Correlated electron-nuclear dissociation dynamics: classical versus quantum motion

NASA Astrophysics Data System (ADS)

Schaupp, Thomas; Albert, Julian; Engel, Volker

2017-01-01

We investigate the coupled electron-nuclear dynamics in a model system which undergoes dissociation. In choosing different initial conditions, the cases of adiabatic and non-adiabatic dissociation are realized. We treat the coupled electronic and nuclear motion in the complete configuration space so that classically, no surface hopping procedures have to be incorporated in the case that more than a single adiabatic electronic state is populated during the fragmentation. Due to the anharmonic interaction potential, it is expected that classical mechanics substantially deviate from quantum mechanics. However, we provide examples where the densities and fragmentation yields obtained from the two treatments are in astonishingly strong agreement in the case that one starts in the electronic ground state initially. As expected, larger deviations are found if one starts in electronically excited states where trajectories are sampled from the more spatially extended electronic wave function. In that case, higher initial energies are accessed, and the motion proceeds in regions with increasing degree of anharmonicity. Contribution to the Topical Issue "Dynamics of Molecular Systems (MOLEC 2016)", edited by Alberto Garcia-Vela, Luis Banares and Maria Luisa Senent.

Observations of Anomalous Refraction with Co-housed Telescopes

NASA Astrophysics Data System (ADS)

Taylor, Malinda S.; McGraw, J. T.; Zimmer, P. C.

2013-01-01

Anomalous refraction is described as a low frequency, large angular scale motion of the entire image plane with respect to the celestial coordinate system as observed and defined by previous astrometric catalogs. These motions of typically several tenths of an arcsecond with timescales on the order of ten minutes are ubiquitous to drift-scan ground-based astrometric measurements regardless of location or telescopes used and have been attributed to meter scale slowly evolving coherent dynamical structures in the boundary-layer below 60 meters. The localized nature of the effect and general inconsistency of the motions seen by even closely spaced telescopes in individual domes has led to the hypothesis that the dome or other type of telescope housing may be responsible. This hypothesis is tested by observing anomalous refraction using two telescopes housed in a single roll-off roof observatory building with the expected outcome that the two telescopes will see correlated anomalous refraction induced motions.

Incremental Dynamic Analysis of Koyna Dam under Repeated Ground Motions

NASA Astrophysics Data System (ADS)

Zainab Nik Azizan, Nik; Majid, Taksiah A.; Nazri, Fadzli Mohamed; Maity, Damodar; Abdullah, Junaidah

2018-03-01

This paper discovers the incremental dynamic analysis (IDA) of concrete gravity dam under single and repeated earthquake loadings to identify the limit state of the dam. Seven ground motions with horizontal and vertical direction as seismic input considered in the nonlinear dynamic analysis based on the real repeated earthquake in the worldwide. All the ground motions convert to respond spectrum and scaled according to the developed elastic respond spectrum in order to match the characteristic of the ground motion to the soil type. The scaled was depends on the fundamental period, T1 of the dam. The Koyna dam has been selected as a case study for the purpose of the analysis by assuming that no sliding and rigid foundation, has been estimated. IDA curves for Koyna dam developed for single and repeated ground motions and the performance level of the dam identifies. The IDA curve of repeated ground motion shown stiffer rather than single ground motion. The ultimate state displacement for a single event is 45.59mm and decreased to 39.33mm under repeated events which are decreased about 14%. This showed that the performance level of the dam based on seismic loadings depend on ground motion pattern.

Determination of Torsional Barriers of Itaconic Acid and N-Acetylethanolamine Using Chirped-Pulsed Ftmw Spectroscopy

NASA Astrophysics Data System (ADS)

Bailey, Josiah R.; McMahon, Timothy J.; Bird, Ryan G.; Pratt, David

2015-06-01

The ground state rotational spectrum of itaconic acid (methylenesuccinic acid) and N-acetylethanolamine (AEA) have been collected and analyzed over the frequency range of 7-17.5 GHz. Both molecules displayed an unexpected tunneling splitting pattern caused by a V2 and V3 barriers, respectively. AEA's methyl rotor is directly connected to a carbonyl and is expected to have too high of a barrier to internal motion. Itaconic acid contains no methyl groups or any symmetry, yet a torsional splitting was observed. The origin of this motion as well their barrier heights and lowest energy conformations will be discussed.

Rupture Directivity Effect on Seismic Vulnerability of Reinforced Concrete Bridge

NASA Astrophysics Data System (ADS)

Shirazian, Shadi; Nouri, Gholamreza; Ghayamghamian, Mohamadreza

2017-04-01

Earthquake catastrophes menace humans` lives and assets. Although earthquakes are inevitable, damage is not. To remedy this situation, significant amount of research is conducted in order to assess the performance of existent man-made structures, particularly infrastructures such as bridges which play a vital role in post earthquake services. The results can be used for assessing retrofit prioritization for structures and as a basis for economic loss estimations. The research presented here determines the vulnerability of a common typical two-span reinforced concrete bridge by generating fragility curves. Near-fault ground motions are different from ordinary ground motions, often containing strong coherent dynamic long-period pulses and permanent ground displacements. Here special attention is given to this type of ground motions, and their effects on the seismic behavior of structure are compared with ordinary motions. The results show near-fault ground motions exacerbate the seismic vulnerability of a bridge by about 68% in comparison with near-field ground motions. In other words, near-source ground motions with forward directivity effect are more dangerous.

Variability in wood-frame building damage using broad-band synthetic ground motions: a comparative numerical study with recorded motions

USGS Publications Warehouse

Pei, Shiling; van de Lindt, John W.; Hartzell, Stephen; Luco, Nicolas

2014-01-01

Earthquake damage to light-frame wood buildings is a major concern for North America because of the volume of this construction type. In order to estimate wood building damage using synthetic ground motions, we need to verify the ability of synthetically generated ground motions to simulate realistic damage for this structure type. Through a calibrated damage potential indicator, four different synthetic ground motion models are compared with the historically recorded ground motions at corresponding sites. We conclude that damage for sites farther from the fault (>20 km) is under-predicted on average and damage at closer sites is sometimes over-predicted.

The 26 January 2001 M 7.6 Bhuj, India, earthquake: Observed and predicted ground motions

USGS Publications Warehouse

Hough, S.E.; Martin, S.; Bilham, R.; Atkinson, G.M.

2002-01-01

Although local and regional instrumental recordings of the devastating 26, January 2001, Bhuj earthquake are sparse, the distribution of macroseismic effects can provide important constraints on the mainshock ground motions. We compiled available news accounts describing damage and other effects and interpreted them to obtain modified Mercalli intensities (MMIs) at >200 locations throughout the Indian subcontinent. These values are then used to map the intensity distribution throughout the subcontinent using a simple mathematical interpolation method. Although preliminary, the maps reveal several interesting features. Within the Kachchh region, the most heavily damaged villages are concentrated toward the western edge of the inferred fault, consistent with western directivity. Significant sediment-induced amplification is also suggested at a number of locations around the Gulf of Kachchh to the south of the epicenter. Away from the Kachchh region, intensities were clearly amplified significantly in areas that are along rivers, within deltas, or on coastal alluvium, such as mudflats and salt pans. In addition, we use fault-rupture parameters inferred from teleseismic data to predict shaking intensity at distances of 0-1000 km. We then convert the predicted hard-rock ground-motion parameters to MMI by using a relationship (derived from Internet-based intensity surveys) that assigns MMI based on the average effects in a region. The predicted MMIs are typically lower by 1-3 units than those estimated from news accounts, although they do predict near-field ground motions of approximately 80%g and potentially damaging ground motions on hard-rock sites to distances of approximately 300 km. For the most part, this discrepancy is consistent with the expected effect of sediment response, but it could also reflect other factors, such as unusually high building vulnerability in the Bhuj region and a tendency for media accounts to focus on the most dramatic damage, rather than the average effects. The discrepancy may also be partly attributable to the inadequacy of the empirical relationship between MMI and peak ground acceleration (PGA), when applied to India. The MMI-PGA relationship was developed using data from California earthquakes, which might have a systematically different stress drop and therefore, a different frequency content than intraplate events. When a relationship between response spectra and MMI is used, we obtain larger predicted MMI values, in better agreement with the observations.

Modeling of earthquake ground motion in the frequency domain

NASA Astrophysics Data System (ADS)

Thrainsson, Hjortur

In recent years, the utilization of time histories of earthquake ground motion has grown considerably in the design and analysis of civil structures. It is very unlikely, however, that recordings of earthquake ground motion will be available for all sites and conditions of interest. Hence, there is a need for efficient methods for the simulation and spatial interpolation of earthquake ground motion. In addition to providing estimates of the ground motion at a site using data from adjacent recording stations, spatially interpolated ground motions can also be used in design and analysis of long-span structures, such as bridges and pipelines, where differential movement is important. The objective of this research is to develop a methodology for rapid generation of horizontal earthquake ground motion at any site for a given region, based on readily available source, path and site characteristics, or (sparse) recordings. The research includes two main topics: (i) the simulation of earthquake ground motion at a given site, and (ii) the spatial interpolation of earthquake ground motion. In topic (i), models are developed to simulate acceleration time histories using the inverse discrete Fourier transform. The Fourier phase differences, defined as the difference in phase angle between adjacent frequency components, are simulated conditional on the Fourier amplitude. Uniformly processed recordings from recent California earthquakes are used to validate the simulation models, as well as to develop prediction formulas for the model parameters. The models developed in this research provide rapid simulation of earthquake ground motion over a wide range of magnitudes and distances, but they are not intended to replace more robust geophysical models. In topic (ii), a model is developed in which Fourier amplitudes and Fourier phase angles are interpolated separately. A simple dispersion relationship is included in the phase angle interpolation. The accuracy of the interpolation model is assessed using data from the SMART-1 array in Taiwan. The interpolation model provides an effective method to estimate ground motion at a site using recordings from stations located up to several kilometers away. Reliable estimates of differential ground motion are restricted to relatively limited ranges of frequencies and inter-station spacings.

Near Real-Time Earthquake Exposure and Damage Assessment: An Example from Turkey

NASA Astrophysics Data System (ADS)

Kamer, Yavor; Çomoǧlu, Mustafa; Erdik, Mustafa

2014-05-01

Confined by infamous strike-slip North Anatolian Fault from the north and by the Hellenic subduction trench from the south Turkey is one of the most seismically active countries in Europe. Due this increased exposure and the fragility of the building stock Turkey is among the top countries exposed to earthquake hazard in terms of mortality and economic losses. In this study we focus recent and ongoing efforts to mitigate the earthquake risk in near real-time. We present actual results of recent earthquakes, such as the M6 event off-shore Antalya which occurred on 28 December 2013. Starting at the moment of detection, we obtain a preliminary ground motion intensity distribution based on epicenter and magnitude. Our real-time application is further enhanced by the integration of the SeisComp3 ground motion parameter estimation tool with the Earthquake Loss Estimation Routine (ELER). SeisComp3 provides the online station parameters which are then automatically incorporated into the ShakeMaps produced by ELER. The resulting ground motion distributions are used together with the building inventory to calculate expected number of buildings in various damage states. All these analysis are conducted in an automated fashion and are communicated within a few minutes of a triggering event. In our efforts to disseminate earthquake information to the general public we make extensive use of social networks such as Tweeter and collaborate with mobile phone operators.

The SCEC Broadband Platform: Open-Source Software for Strong Ground Motion Simulation and Validation

NASA Astrophysics Data System (ADS)

Silva, F.; Goulet, C. A.; Maechling, P. J.; Callaghan, S.; Jordan, T. H.

2016-12-01

The Southern California Earthquake Center (SCEC) Broadband Platform (BBP) is a carefully integrated collection of open-source scientific software programs that can simulate broadband (0-100 Hz) ground motions for earthquakes at regional scales. The BBP can run earthquake rupture and wave propagation modeling software to simulate ground motions for well-observed historical earthquakes and to quantify how well the simulated broadband seismograms match the observed seismograms. The BBP can also run simulations for hypothetical earthquakes. In this case, users input an earthquake location and magnitude description, a list of station locations, and a 1D velocity model for the region of interest, and the BBP software then calculates ground motions for the specified stations. The BBP scientific software modules implement kinematic rupture generation, low- and high-frequency seismogram synthesis using wave propagation through 1D layered velocity structures, several ground motion intensity measure calculations, and various ground motion goodness-of-fit tools. These modules are integrated into a software system that provides user-defined, repeatable, calculation of ground-motion seismograms, using multiple alternative ground motion simulation methods, and software utilities to generate tables, plots, and maps. The BBP has been developed over the last five years in a collaborative project involving geoscientists, earthquake engineers, graduate students, and SCEC scientific software developers. The SCEC BBP software released in 2016 can be compiled and run on recent Linux and Mac OS X systems with GNU compilers. It includes five simulation methods, seven simulation regions covering California, Japan, and Eastern North America, and the ability to compare simulation results against empirical ground motion models (aka GMPEs). The latest version includes updated ground motion simulation methods, a suite of new validation metrics and a simplified command line user interface.

2001 Bhuj, India, earthquake engineering seismoscope recordings and Eastern North America ground-motion attenuation relations

USGS Publications Warehouse

Cramer, C.H.; Kumar, A.

2003-01-01

Engineering seismoscope data collected at distances less than 300 km for the M 7.7 Bhuj, India, mainshock are compatible with ground-motion attenuation in eastern North America (ENA). The mainshock ground-motion data have been corrected to a common geological site condition using the factors of Joyner and Boore (2000) and a classification scheme of Quaternary or Tertiary sediments or rock. We then compare these data to ENA ground-motion attenuation relations. Despite uncertainties in recording method, geological site corrections, common tectonic setting, and the amount of regional seismic attenuation, the corrected Bhuj dataset agrees with the collective predictions by ENA ground-motion attenuation relations within a factor of 2. This level of agreement is within the dataset uncertainties and the normal variance for recorded earthquake ground motions.

Evaluation of seismic performance of reinforced concrete (RC) buildings under near-field earthquakes

NASA Astrophysics Data System (ADS)

Moniri, Hassan

2017-03-01

Near-field ground motions are significantly severely affected on seismic response of structure compared with far-field ground motions, and the reason is that the near-source forward directivity ground motions contain pulse-long periods. Therefore, the cumulative effects of far-fault records are minor. The damage and collapse of engineering structures observed in the last decades' earthquakes show the potential of damage in existing structures under near-field ground motions. One important subject studied by earthquake engineers as part of a performance-based approach is the determination of demand and collapse capacity under near-field earthquake. Different methods for evaluating seismic structural performance have been suggested along with and as part of the development of performance-based earthquake engineering. This study investigated the results of illustrious characteristics of near-fault ground motions on the seismic response of reinforced concrete (RC) structures, by the use of Incremental Nonlinear Dynamic Analysis (IDA) method. Due to the fact that various ground motions result in different intensity-versus-response plots, this analysis is done again under various ground motions in order to achieve significant statistical averages. The OpenSees software was used to conduct nonlinear structural evaluations. Numerical modelling showed that near-source outcomes cause most of the seismic energy from the rupture to arrive in a single coherent long-period pulse of motion and permanent ground displacements. Finally, a vulnerability of RC building can be evaluated against pulse-like near-fault ground motions effects.

A revised ground-motion and intensity interpolation scheme for shakemap

USGS Publications Warehouse

Worden, C.B.; Wald, D.J.; Allen, T.I.; Lin, K.; Garcia, D.; Cua, G.

2010-01-01

We describe a weighted-average approach for incorporating various types of data (observed peak ground motions and intensities and estimates from groundmotion prediction equations) into the ShakeMap ground motion and intensity mapping framework. This approach represents a fundamental revision of our existing ShakeMap methodology. In addition, the increased availability of near-real-time macroseismic intensity data, the development of newrelationships between intensity and peak ground motions, and new relationships to directly predict intensity from earthquake source information have facilitated the inclusion of intensity measurements directly into ShakeMap computations. Our approach allows for the combination of (1) direct observations (ground-motion measurements or reported intensities), (2) observations converted from intensity to ground motion (or vice versa), and (3) estimated ground motions and intensities from prediction equations or numerical models. Critically, each of the aforementioned data types must include an estimate of its uncertainties, including those caused by scaling the influence of observations to surrounding grid points and those associated with estimates given an unknown fault geometry. The ShakeMap ground-motion and intensity estimates are an uncertainty-weighted combination of these various data and estimates. A natural by-product of this interpolation process is an estimate of total uncertainty at each point on the map, which can be vital for comprehensive inventory loss calculations. We perform a number of tests to validate this new methodology and find that it produces a substantial improvement in the accuracy of ground-motion predictions over empirical prediction equations alone.

Deficient motion-defined and texture-defined figure-ground segregation in amblyopic children.

PubMed

Wang, Jane; Ho, Cindy S; Giaschi, Deborah E

2007-01-01

Motion-defined form deficits in the fellow eye and the amblyopic eye of children with amblyopia implicate possible direction-selective motion processing or static figure-ground segregation deficits. Deficient motion-defined form perception in the fellow eye of amblyopic children may not be fully accounted for by a general motion processing deficit. This study investigates the contribution of figure-ground segregation deficits to the motion-defined form perception deficits in amblyopia. Performances of 6 amblyopic children (5 anisometropic, 1 anisostrabismic) and 32 control children with normal vision were assessed on motion-defined form, texture-defined form, and global motion tasks. Performance on motion-defined and texture-defined form tasks was significantly worse in amblyopic children than in control children. Performance on global motion tasks was not significantly different between the 2 groups. Faulty figure-ground segregation mechanisms are likely responsible for the observed motion-defined form perception deficits in amblyopia.

Empirical development of ground acceleration, velocity, and displacement for accidental explosions at J5 or the proposed large altitude rocket cell at Arnold Engineering Development Center

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

Davis, B.C.

This study is an assessment of the ground shock which may be generated in the event of an accidental explosion at J5 or the Proposed Large Altitude Rocket Cell (LARC) at the Arnold Engineering Development Center (AEDC). The assessment is accomplished by reviewing existing empirical relationships for predicting ground motion from ground shock. These relationships are compared with data for surface explosions at sites with similar geology and with yields similar to expected conditions at AEDC. Empirical relationships are developed from these data and a judgment made whether to use existing empirical relationships or the relationships developed in this study.more » An existing relationship (Lipner et al.) is used to predict velocity; the empirical relationships developed in the course of this study are used to predict acceleration and displacement. The ground motions are presented in table form and as contour plots. Included also is a discussion of damage criteria from blast and earthquake studies. This report recommends using velocity rather than acceleration as an indicator of structural blast damage. It is recommended that v = 2 ips (v = .167 fps) be used as the damage threshold value (no major damage for v less than or equal to 2 ips). 13 references, 25 figures, 6 tables.« less

Synthesis of High-Frequency Ground Motion Using Information Extracted from Low-Frequency Ground Motion

NASA Astrophysics Data System (ADS)

Iwaki, A.; Fujiwara, H.

2012-12-01

Broadband ground motion computations of scenario earthquakes are often based on hybrid methods that are the combinations of deterministic approach in lower frequency band and stochastic approach in higher frequency band. Typical computation methods for low-frequency and high-frequency (LF and HF, respectively) ground motions are the numerical simulations, such as finite-difference and finite-element methods based on three-dimensional velocity structure model, and the stochastic Green's function method, respectively. In such hybrid methods, LF and HF wave fields are generated through two different methods that are completely independent of each other, and are combined at the matching frequency. However, LF and HF wave fields are essentially not independent as long as they are from the same event. In this study, we focus on the relation among acceleration envelopes at different frequency bands, and attempt to synthesize HF ground motion using the information extracted from LF ground motion, aiming to propose a new method for broad-band strong motion prediction. Our study area is Kanto area, Japan. We use the K-NET and KiK-net surface acceleration data and compute RMS envelope at four frequency bands: 0.5-1.0 Hz, 1.0-2.0 Hz, 2.0-4.0 Hz, .0-8.0 Hz, and 8.0-16.0 Hz. Taking the ratio of the envelopes of adjacent bands, we find that the envelope ratios have stable shapes at each site. The empirical envelope-ratio characteristics are combined with low-frequency envelope of the target earthquake to synthesize HF ground motion. We have applied the method to M5-class earthquakes and a M7 target earthquake that occurred in the vicinity of Kanto area, and successfully reproduced the observed HF ground motion of the target earthquake. The method can be applied to a broad band ground motion simulation for a scenario earthquake by combining numerically-computed low-frequency (~1 Hz) ground motion with the empirical envelope ratio characteristics to generate broadband ground motion. The strengths of the proposed method are that: 1) it is based on observed ground motion characteristics, 2) it takes full advantage of precise velocity structure model, and 3) it is simple and easy to apply.

Point-source stochastic-method simulations of ground motions for the PEER NGA-East Project

USGS Publications Warehouse

Boore, David

2015-01-01

Ground-motions for the PEER NGA-East project were simulated using a point-source stochastic method. The simulated motions are provided for distances between of 0 and 1200 km, M from 4 to 8, and 25 ground-motion intensity measures: peak ground velocity (PGV), peak ground acceleration (PGA), and 5%-damped pseudoabsolute response spectral acceleration (PSA) for 23 periods ranging from 0.01 s to 10.0 s. Tables of motions are provided for each of six attenuation models. The attenuation-model-dependent stress parameters used in the stochastic-method simulations were derived from inversion of PSA data from eight earthquakes in eastern North America.

Assessment of Simulated Ground Motions in Earthquake Engineering Practice: A Case Study for Duzce (Turkey)

NASA Astrophysics Data System (ADS)

Karimzadeh, Shaghayegh; Askan, Aysegul; Yakut, Ahmet

2017-09-01

Simulated ground motions can be used in structural and earthquake engineering practice as an alternative to or to augment the real ground motion data sets. Common engineering applications of simulated motions are linear and nonlinear time history analyses of building structures, where full acceleration records are necessary. Before using simulated ground motions in such applications, it is important to assess those in terms of their frequency and amplitude content as well as their match with the corresponding real records. In this study, a framework is outlined for assessment of simulated ground motions in terms of their use in structural engineering. Misfit criteria are determined for both ground motion parameters and structural response by comparing the simulated values against the corresponding real values. For this purpose, as a case study, the 12 November 1999 Duzce earthquake is simulated using stochastic finite-fault methodology. Simulated records are employed for time history analyses of frame models of typical residential buildings. Next, the relationships between ground motion misfits and structural response misfits are studied. Results show that the seismological misfits around the fundamental period of selected buildings determine the accuracy of the simulated responses in terms of their agreement with the observed responses.

QuakeUp: An advanced tool for a network-based Earthquake Early Warning system

NASA Astrophysics Data System (ADS)

Zollo, Aldo; Colombelli, Simona; Caruso, Alessandro; Elia, Luca; Brondi, Piero; Emolo, Antonio; Festa, Gaetano; Martino, Claudio; Picozzi, Matteo

2017-04-01

The currently developed and operational Earthquake Early warning, regional systems ground on the assumption of a point-like earthquake source model and 1-D ground motion prediction equations to estimate the earthquake impact. Here we propose a new network-based method which allows for issuing an alert based upon the real-time mapping of the Potential Damage Zone (PDZ), e.g. the epicentral area where the peak ground velocity is expected to exceed the damaging or strong shaking levels with no assumption about the earthquake rupture extent and spatial variability of ground motion. The platform includes the most advanced techniques for a refined estimation of the main source parameters (earthquake location and magnitude) and for an accurate prediction of the expected ground shaking level. The new software platform (QuakeUp) is under development at the Seismological Laboratory (RISSC-Lab) of the Department of Physics at the University of Naples Federico II, in collaboration with the academic spin-off company RISS s.r.l., recently gemmated by the research group. The system processes the 3-component, real-time ground acceleration and velocity data streams at each station. The signal quality is preliminary assessed by checking the signal-to-noise ratio both in acceleration, velocity and displacement and through dedicated filtering algorithms. For stations providing high quality data, the characteristic P-wave period (τ_c) and the P-wave displacement, velocity and acceleration amplitudes (P_d, Pv and P_a) are jointly measured on a progressively expanded P-wave time window. The evolutionary measurements of the early P-wave amplitude and characteristic period at stations around the source allow to predict the geometry and extent of PDZ, but also of the lower shaking intensity regions at larger epicentral distances. This is done by correlating the measured P-wave amplitude with the Peak Ground Velocity (PGV) and Instrumental Intensity (I_MM) and by mapping the measured and predicted P-wave amplitude at a dense spatial grid, including the nodes of the accelerometer/velocimeter array deployed in the earthquake source area. Within times of the order of ten seconds from the earthquake origin, the information about the area where moderate to strong ground shaking is expected to occur, can be sent to inner and outer sites, allowing the activation of emergency measurements to protect people , secure industrial facilities and optimize the site resilience after the disaster. Depending of the network density and spatial source coverage, this method naturally accounts for effects related to the earthquake rupture extent (e.g. source directivity) and spatial variability of strong ground motion related to crustal wave propagation and site amplification. In QuakeUp, the P-wave parameters are continuously measured, using progressively expanded P-wave time windows, and providing evolutionary and reliable estimates of the ground shaking distribution, especially in the case of very large events. Furthermore, to minimize the S-wave contamination on the P-wave signal portion, an efficient algorithm, based on the real-time polarization analysis of the three-component seismogram, for the automatic detection of the S-wave arrival time has been included. The final output of QuakeUp will be an automatic alert message that is transmitted to sites to be secured during the earthquake emergency. The message contains all relevant information about the expected potential damage at the site and the time available for security actions (lead-time) after the warning. A global view of the system performance during and after the event (in play-back mode) is obtained through an end-user visual display, where the most relevant pieces of information will be displayed and updated as soon as new data are available. The software platform Quake-Up is essentially aimed at improving the reliability and the accuracy in terms of parameter estimation, minimizing the uncertainties in the real-time estimations without losing the essential requirements of speediness and robustness, which are needed to activate rapid emergency actions.

Tidally induced variations in vertical and horizontal motion on Rutford Ice Stream, West Antarctica, inferred from remotely sensed observations

NASA Astrophysics Data System (ADS)

Minchew, B. M.; Simons, M.; Riel, B.; Milillo, P.

2017-01-01

To better understand the influence of stress changes over floating ice shelves on grounded ice streams, we develop a Bayesian method for inferring time-dependent 3-D surface velocity fields from synthetic aperture radar (SAR) and optical remote sensing data. Our specific goal is to observe ocean tide-induced variability in vertical ice shelf position and horizontal ice stream flow. Thus, we consider the special case where observed surface displacement at a given location can be defined by a 3-D secular velocity vector, a family of 3-D sinusoidal functions, and a correction to the digital elevation model used to process the SAR data. Using nearly 9 months of SAR data collected from multiple satellite viewing geometries with the COSMO-SkyMed 4-satellite constellation, we infer the spatiotemporal response of Rutford Ice Stream, West Antarctica, to ocean tidal forcing. Consistent with expected tidal uplift, inferred vertical motion over the ice shelf is dominated by semidiurnal and diurnal tidal constituents. Horizontal ice flow variability, on the other hand, occurs primarily at the fortnightly spring-neap tidal period (Msf). We propose that periodic grounding of the ice shelf is the primary mechanism for translating vertical tidal motion into horizontal flow variability, causing ice flow to accelerate first and most strongly over the ice shelf. Flow variations then propagate through the grounded ice stream at a mean rate of ˜29 km/d and decay quasi-linearly with distance over ˜85 km upstream of the grounding zone.

The 2011 Mineral, VA M5.8 Earthquake Ground Motions and Stress Drop: An Important Contribution to the NGA East Ground Motion Database

NASA Astrophysics Data System (ADS)

Cramer, C. H.; Kutliroff, J.; Dangkua, D.

2011-12-01

The M5.8 Mineral, Virginia earthquake of August 23, 2011 is the largest instrumentally recorded earthquake in eastern North America since the 1988 M5.9 Saguenay, Canada earthquake. Historically, a similar magnitude earthquake occurred on May 31, 1897 at 18:58 UCT in western Virginia west of Roanoke. Paleoseismic evidence for larger magnitude earthquakes has also been found in the central Virginia region. The Next Generation Attenuation (NGA) East project to develop new ground motion prediction equations for stable continental regions (SCRs), including eastern North America (ENA), is ongoing at the Pacific Earthquake Engineering Research Center funded by the U.S. Nuclear Regulatory Commission, the U.S. Geological Survey, the Electric Power Research Institute, and the U.S. Department of Energy. The available recordings from the M5.8 Virginia are being added to the NGA East ground motion database. Close in (less than 100 km) strong motion recordings are particularly interesting for both ground motion and stress drop estimates as most close-in broadband seismometers clipped on the mainshock. A preliminary estimate for earthquake corner frequency for the M5.8 Virginia earthquake of ~0.7 Hz has been obtained from a strong motion record 57 km from the mainshock epicenter. For a M5.8 earthquake this suggests a Brune stress drop of ~300 bars for the Virginia event. Very preliminary comparisons using accelerometer data suggest the ground motions from the M5.8 Virginia earthquake agree well with current ENA ground motion prediction equations (GMPEs) at short periods (PGA, 0.2 s) and are below the GMPEs at longer periods (1.0 s), which is the same relationship seen from other recent M5 ENA earthquakes. We will present observed versus GMPE ground motion comparisons for all the ground motion observations and stress drop estimates from strong motion recordings at distances less than 100 km. A review of the completed NGA East ENA ground motion database will also be provided.

Analog-to-digital conversion as a source of drifts in displacements derived from digital recordings of ground acceleration

USGS Publications Warehouse

Boore, D.M.

2003-01-01

Displacements obtained from double integration of digitally recorded ground accelerations often show drifts much larger than those expected for the true ground displacements. These drifts might be due to many things, including dynamic elastic ground tilt, inelastic ground deformation, hysteresis in the instruments, and cross feed due to misalignment of nominally orthogonal sensors. This article shows that even if those effects were not present, the analog-to-digital conversion (ADC) process can produce apparent "pulses" and offsets in the acceleration baseline if the ground motion is slowly varying compared with the quantization level of the digitization. Such slowly varying signals can be produced by constant offsets that do not coincide with a quantization level and by near- and intermediate-field terms in the wave field radiated from earthquakes. Double integration of these apparent pulses and offsets leads to drifts in the displacements similar to those found in processing real recordings. These effects decrease in importance as the resolution of the ADC process increases.

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.

Correlations between ground motion and building damage. Engineering intensity scale applied to the San Fernando earthquake of February 1971

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

Hafen, D.; Kintzer, F.C.

1977-11-01

The correlation between ground motion and building damage was investigated for the San Fernando earthquake of 1971. A series of iso-intensity maps was compiled to summarize the ground motion in terms of the Blume Engineering Intensity Scale (EIS). This involved the analysis of ground motion records from 62 stations in the Los Angeles area. Damage information for low-rise buildings was obtained in the form of records of loans granted by the Small Business Administration to repair earthquake damage. High-rise damage evaluations were based on direct inquiry and building inspection. Damage factors (ratio of damage repair cost to building value) weremore » calculated and summarized on contour maps. A statistical study was then undertaken to determine relationships between ground motion and damage factor. Several parameters for ground motion were considered and evaluated by means of correlation coefficients.« less

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.

The ShakeOut earthquake source and ground motion simulations

USGS Publications Warehouse

Graves, R.W.; Houston, Douglas B.; Hudnut, K.W.

2011-01-01

The ShakeOut Scenario is premised upon the detailed description of a hypothetical Mw 7.8 earthquake on the southern San Andreas Fault and the associated simulated ground motions. The main features of the scenario, such as its endpoints, magnitude, and gross slip distribution, were defined through expert opinion and incorporated information from many previous studies. Slip at smaller length scales, rupture speed, and rise time were constrained using empirical relationships and experience gained from previous strong-motion modeling. Using this rupture description and a 3-D model of the crust, broadband ground motions were computed over a large region of Southern California. The largest simulated peak ground acceleration (PGA) and peak ground velocity (PGV) generally range from 0.5 to 1.0 g and 100 to 250 cm/s, respectively, with the waveforms exhibiting strong directivity and basin effects. Use of a slip-predictable model results in a high static stress drop event and produces ground motions somewhat higher than median level predictions from NGA ground motion prediction equations (GMPEs).

Effect of vertical ground motion on earthquake-induced derailment of railway vehicles over simply-supported bridges

NASA Astrophysics Data System (ADS)

Jin, Zhibin; Pei, Shiling; Li, Xiaozhen; Liu, Hongyan; Qiang, Shizhong

2016-11-01

The running safety of railway vehicles on bridges can be negatively affected by earthquake events. This phenomenon has traditionally been investigated with only the lateral ground excitation component considered. This paper presented results from a numerical investigation on the contribution of vertical ground motion component to the derailment of vehicles on simply-supported bridges. A full nonlinear wheel-rail contact model was used in the investigation together with the Hertzian contact theory and nonlinear creepage theory, which allows the wheel to jump vertically and separate from the rail. The wheel-rail relative displacement was used as the criterion for derailment events. A total of 18 ground motion records were used in the analysis to account for the uncertainty of ground motions. The results showed that inclusion of vertical ground motion will likely increase the chance of derailment. It is recommended to include vertical ground motion component in earthquake induced derailment analysis to ensure conservative estimations. The derailment event on bridges was found to be more closely related to the deck acceleration rather than the ground acceleration.

Ground-Motion Variability for a Strike-Slip Earthquake from Broadband Ground-Motion Simulations

NASA Astrophysics Data System (ADS)

Iwaki, A.; Maeda, T.; Morikawa, N.; Fujiwara, H.

2016-12-01

One of the important issues in seismic hazard analysis is the evaluation of ground-motion variability due to the epistemic and aleatory uncertainties in various aspects of ground-motion simulations. This study investigates the within-event ground-motion variability in broadband ground-motion simulations for strike-slip events. We conduct ground-motion simulations for a past event (2000 MW6.6 Tottori earthquake) using a set of characterized source models (e.g. Irikura and Miyake, 2011) considering aleatory variability. Broadband ground motion is computed by a hybrid approach that combines a 3D finite-difference method (> 1 s) and the stochastic Green's function method (< 1 s), using the 3D velocity model J-SHIS v2. We consider various locations of the asperities, which are defined as the regions with large slip and stress drop within the fault, and the rupture nucleation point (hypocenter). Ground motion records at 29 K-NET and KiK-net stations are used to validate our simulations. By comparing the simulated and observed ground motion, we found that the performance of the simulations is acceptable under the condition that the source parameters are poorly constrained. In addition to the observation stations, we set 318 virtual receivers with the spatial intervals of 10 km for statistical analysis of the simulated ground motion. The maximum fault-distance is 160 km. Standard deviation (SD) of the simulated acceleration response spectra (Sa, 5% damped) of RotD50 component (Boore, 2010) is investigated at each receiver. SD from 50 different patterns of asperity locations is generally smaller than 0.15 in terms of log10 (0.34 in natural log). It shows dependence on distance at periods shorter than 1 s; SD increases as the distance decreases. On the other hand, SD from 39 different hypocenter locations is again smaller than 0.15 in log10, and showed azimuthal dependence at long periods; it increases as the rupture directivity parameter Xcosθ(Somerville et al. 1997) increases at periods longer than 1 s. The characteristics of ground-motion variability inferred from simulations can provide information on variability in simulation-based seismic hazard assessment for future earthquakes. We will further investigate the variability in other source parameters; rupture velocity and short-period level.

Model and parametric uncertainty in source-based kinematic models of earthquake ground motion

USGS Publications Warehouse

Hartzell, Stephen; Frankel, Arthur; Liu, Pengcheng; Zeng, Yuehua; Rahman, Shariftur

2011-01-01

Four independent ground-motion simulation codes are used to model the strong ground motion for three earthquakes: 1994 Mw 6.7 Northridge, 1989 Mw 6.9 Loma Prieta, and 1999 Mw 7.5 Izmit. These 12 sets of synthetics are used to make estimates of the variability in ground-motion predictions. In addition, ground-motion predictions over a grid of sites are used to estimate parametric uncertainty for changes in rupture velocity. We find that the combined model uncertainty and random variability of the simulations is in the same range as the variability of regional empirical ground-motion data sets. The majority of the standard deviations lie between 0.5 and 0.7 natural-log units for response spectra and 0.5 and 0.8 for Fourier spectra. The estimate of model epistemic uncertainty, based on the different model predictions, lies between 0.2 and 0.4, which is about one-half of the estimates for the standard deviation of the combined model uncertainty and random variability. Parametric uncertainty, based on variation of just the average rupture velocity, is shown to be consistent in amplitude with previous estimates, showing percentage changes in ground motion from 50% to 300% when rupture velocity changes from 2.5 to 2.9 km/s. In addition, there is some evidence that mean biases can be reduced by averaging ground-motion estimates from different methods.

Ground-motion prediction from tremor

USGS Publications Warehouse

Baltay, Annemarie S.; Beroza, Gregory C.

2013-01-01

The widespread occurrence of tremor, coupled with its frequency content and location, provides an exceptional opportunity to test and improve strong ground-motion attenuation relations for subduction zones. We characterize the amplitude of thousands of individual 5 min tremor events in Cascadia during three episodic tremor and slip events to constrain the distance decay of peak ground acceleration (PGA) and peak ground velocity (PGV). We determine the anelastic attenuation parameter for ground-motion prediction equations (GMPEs) to a distance of 150 km, which is sufficient to place important constraints on ground-motion decay. Tremor PGA and PGV show a distance decay that is similar to subduction-zone-specific GMPEs developed from both data and simulations; however, the massive amount of data present in the tremor observations should allow us to refine distance-amplitude attenuation relationships for use in hazard maps, and to search for regional variations and intrasubduction zone differences in ground-motion attenuation.

Fake ballistics and real explosions: field-scale experiments on the ejection and emplacement of volcanic bombs during vent-clearing explosive activity

NASA Astrophysics Data System (ADS)

Taddeucci, J.; Valentine, G.; Gaudin, D.; Graettinger, A. H.; Lube, G.; Kueppers, U.; Sonder, I.; White, J. D.; Ross, P.; Bowman, D. C.

2013-12-01

Ballistics - bomb-sized pyroclasts that travel from volcanic source to final emplacement position along ballistic trajectories - represent a prime source of volcanic hazard, but their emplacement range, size, and density is useful to inverse model key eruption parameters related to their initial ejection velocity. Models and theory, however, have so far focused on the trajectory of ballistics after leaving the vent, neglecting the complex dynamics of their initial acceleration phase in the vent/conduit. Here, we use field-scale buried explosion experiments to study the ground-to-ground ballistic emplacement of particles through their entire acceleration-deceleration cycle. Twelve blasts were performed at the University at Buffalo Large Scale Experimental Facility with a range of scaled depths (burial depth divided by the cubic root of the energy of the explosive charge) and crater configurations. In all runs, ballistic analogs were placed on the ground surface at variable distance from the vertical projection of the buried charge, resulting in variable ejection angle. The chosen analogs are tennis and ping-pong balls filled with different materials, covering a limited range of sizes and densities. The analogs are tracked in multiple high-speed and high-definition videos, while Particle Image Velocimetry is used to detail ground motion in response to the buried blasts. In addition, after each blast the emplacement position of all analog ballistics was mapped with respect to the blast location. Preliminary results show the acceleration history of ballistics to be quite variable, from very short and relatively simple acceleration coupled with ground motion, to more complex, multi-stage accelerations possibly affected not only by the initial ground motion but also by variable coupling with the gas-particle mixture generated by the blasts. Further analysis of the experimental results is expected to provide new interpretative tools for ballistic deposits and better hazard assessment, with particular emphasis for the case of vent-opening eruptions driven by explosive gas expansion beneath loose debris.

What can we learn from the Wells, NV earthquake sequence about seismic hazard in the intermountain west?

USGS Publications Warehouse

Petersen, M.D.; Pankow, K.L.; Biasi, G.P.; Meremonte, M.

2008-01-01

The February 21, 2008 Wells, NV earthquake (M 6) was felt throughout eastern Nevada, southern Idaho, and western Utah. The town of Wells sustained significant damage to unreinforced masonry buildings. The earthquake occurred in a region of low seismic hazard with little seismicity, low geodetic strain rates, and few mapped faults. The peak horizontal ground acceleration predicted by the USGS National Seismic Hazard Maps is about 0.2 g at 2% probability of exceedance in 50 years, with the contributions coming mostly from the Ruby Mountain fault and background seismicity (M5-7.0). The hazard model predicts that the probability of occurrence of an M>6 event within 50 km of Wells is about 15% in 100 years. Although the earthquake was inside the USArray Transportable Array network, the nearest on-scale recordings of ground motions from the mainshock were too distant to estimate accelerations in town. The University of Nevada Reno, the University of Utah, and the U.S. Geological Survey deployed portable instruments to capture the ground motions from aftershocks of this rare normal-faulting event. Shaking from a M 4.7 aftershock recorded on portable instruments at distances less than 10 km exceeded 0.3 g, and sustained accelerations above 0.1 g lasted for about 5 seconds. For a magnitude 5 earthquake at 10 km distance the NGA equations predict median peak ground accelerations about 0.1 g. Ground motions from normal faulting earthquakes are poorly represented in the ground motion prediction equations. We compare portable and Transportable Array ground-motion recordings with prediction equations. Advanced National Seismic System stations in Utah recorded ground motions 250 km from the mainshock of about 2% g. The maximum ground motion recorded in Salt Lake City was in the center of the basin. We analyze the spatial variability of ground motions (rock vs. soil) and the influence of the Salt Lake Basin in modifying the ground motions. We then compare this data with the September 28, 2004 Parkfield aftershocks to contrast the differences between strike-slip and normal ground motions.

A short note on ground-motion recordings from the M 7.9 Wenchuan, China, earthquake and ground-motion prediction equations in the Central and Eastern United States

USGS Publications Warehouse

Wang, Z.; Lu, M.

2011-01-01

The 12 May 2008 Wenchuan earthquake (M 7.9) occurred along the western edge of the eastern China SCR and was well recorded by modern strong-motion instruments: 93 strong-motion stations within 1.4 to 300 km rupture distance recorded the main event. Preliminary comparisons show some similarities between ground-motion attenuation in the Wenchuan region and the central and eastern United States, suggesting that ground motions from the Wenchuan earthquake could be used as a database providing constraints for developing GMPEs for large earthquakes in the central and eastern United States.

Empirical Ground Motion Characterization of Induced Seismicity in Alberta and Oklahoma

NASA Astrophysics Data System (ADS)

Novakovic, M.; Atkinson, G. M.; Assatourians, K.

2017-12-01

We develop empirical ground-motion prediction equations (GMPEs) for ground motions from induced earthquakes in Alberta and Oklahoma following the stochastic-model-based method of Atkinson et al. (2015 BSSA). The Oklahoma ground-motion database is compiled from over 13,000 small to moderate seismic events (M 1 to 5.8) recorded at 1600 seismic stations, at distances from 1 to 750 km. The Alberta database is compiled from over 200 small to moderate seismic events (M 1 to 4.2) recorded at 50 regional stations, at distances from 30 to 500 km. A generalized inversion is used to solve for regional source, attenuation and site parameters. The obtained parameters describe the regional attenuation, stress parameter and site amplification. Resolving these parameters allows for the derivation of regionally-calibrated GMPEs that can be used to compare ground motion observations between waste water injection (Oklahoma) and hydraulic fracture induced events (Alberta), and further compare induced observations with ground motions resulting from natural sources (California, NGAWest2). The derived GMPEs have applications for the evaluation of hazards from induced seismicity and can be used to track amplitudes across the regions in real time, which is useful for ground-motion-based alerting systems and traffic light protocols.

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).

High Frequency Ground Motion from Finite Fault Rupture Simulations

NASA Astrophysics Data System (ADS)

Crempien, Jorge G. F.

There are many tectonically active regions on earth with little or no recorded ground motions. The Eastern United States is a typical example of regions with active faults, but with low to medium seismicity that has prevented sufficient ground motion recordings. Because of this, it is necessary to use synthetic ground motion methods in order to estimate the earthquake hazard a region might have. Ground motion prediction equations for spectral acceleration typically have geometric attenuation proportional to the inverse of distance away from the fault. Earthquakes simulated with one-dimensional layered earth models have larger geometric attenuation than the observed ground motion recordings. We show that as incident angles of rays increase at welded boundaries between homogeneous flat layers, the transmitted rays decrease in amplitude dramatically. As the receiver distance increases away from the source, the angle of incidence of up-going rays increases, producing negligible transmitted ray amplitude, thus increasing the geometrical attenuation. To work around this problem we propose a model in which we separate wave propagation for low and high frequencies at a crossover frequency, typically 1Hz. The high-frequency portion of strong ground motion is computed with a homogeneous half-space and amplified with the available and more complex one- or three-dimensional crustal models using the quarter wavelength method. We also make use of seismic coda energy density observations as scattering impulse response functions. We incorporate scattering impulse response functions into our Green's functions by convolving the high-frequency homogeneous half-space Green's functions with normalized synthetic scatterograms to reproduce scattering physical effects in recorded seismograms. This method was validated against ground motion for earthquakes recorded in California and Japan, yielding results that capture the duration and spectral response of strong ground motion.

The role of complex site and basin response in Wellington city, New Zealand, during the 2016 Mw 7.8 Kaikōura earthquake and other recent earthquake sequences.

NASA Astrophysics Data System (ADS)

Kaiser, A. E.; McVerry, G.; Wotherspoon, L.; Bradley, B.; Gerstenberger, M.; Benites, R. A.; Bruce, Z.; Bourguignon, S.; Giallini, S.; Hill, M.

2017-12-01

We present analysis of ground motion and complex amplification characteristics in Wellington during recent earthquake sequences and an overview of the 3D basin characterization and ongoing work to update site parameters for seismic design. Significant damage was observed in central Wellington, New Zealand's capital city, following the 2016 Mw7.8 Kaikōura earthquake. Damage was concentrated in mid-rise structures (5 - 15 storeys) and was clearly exacerbated by the particular characteristics of ground motion and the presence of basin effects. Due to the distance of the source (50 - 60km) from the central city, peak ground accelerations were moderate (up to 0.28g) and well within ultimate limit state (ULS) design levels. However, spectral accelerations within the 1 -2 s period range, exceeded 1 in 500 year design level spectra (ULS) in deeper parts of the basin. Amplification with respect to rock at these locations reached factors of up to 7, and was also observed with factors up to at least three across all central city soil recording sites. The ground motions in Wellington were the strongest recorded in the modern era of instrumentation. While similar amplification was observed during the 2013 Mw 6.6 Cook Strait and Grassmere earthquakes, which struck close to the termination of the Kaikōura earthquake rupture, these sources were not sufficiently large to excite significant long-period motions. However, other M7.2+ sources in the region that dominate the seismic hazard, e.g. Wellington Fault, Hikurangi subduction interface and other large proximal crustal faults, are also potentially capable of exciting significant long-period basin response in Wellington. These observations and the expectation of ongoing heightened seismicity have prompted re-evaluation of the current seismic demand levels. Additional field campaigns have also been undertaken to update geotechnical properties and the 3D basin model, in order to inform ongoing research and seismic design practice.

Figure-ground segregation can rely on differences in motion direction.

PubMed

Kandil, Farid I; Fahle, Manfred

2004-12-01

If the elements within a figure move synchronously while those in the surround move at a different time, the figure is easily segregated from the surround and thus perceived. Lee and Blake (1999) [Visual form created solely from temporal structure. Science, 284, 1165-1168] demonstrated that this figure-ground separation may be based not only on time differences between motion onsets, but also on the differences between reversals of motion direction. However, Farid and Adelson (2001) [Synchrony does not promote grouping in temporally structured displays. Nature Neuroscience, 4, 875-876] argued that figure-ground segregation in the motion-reversal experiment might have been based on a contrast artefact and concluded that (a)synchrony as such was 'not responsible for the perception of form in these or earlier displays'. Here, we present experiments that avoid contrast artefacts but still produce figure-ground segregation based on purely temporal cues. Our results show that subjects can segregate figure from ground even though being unable to use motion reversals as such. Subjects detect the figure when either (i) motion stops (leading to contrast artefacts), or (ii) motion directions differ between figure and ground. Segregation requires minimum delays of about 15 ms. We argue that whatever the underlying cues and mechanisms, a second stage beyond motion detection is required to globally compare the outputs of local motion detectors and to segregate figure from ground. Since analogous changes take place in both figure and ground in rapid succession, this second stage has to detect the asynchrony with high temporal precision.

Seismic Hazard Analysis as a Controlling Technique of Induced Seismicity in Geothermal Systems

NASA Astrophysics Data System (ADS)

Convertito, V.; Sharma, N.; Maercklin, N.; Emolo, A.; Zollo, A.

2011-12-01

The effect of induced seismicity of geothermal systems during stimulation and fluid circulation can cover a wide range of values from light and unfelt to severe and damaging. If the design of a modern geothermal system requires the largest efficiency to be obtained from the social point of view it is required that the system could be managed in order to reduce possible impact in advance. In this framework, automatic control of the seismic response of the stimulated reservoir is nowadays mandatory, particularly in proximity of densely populated areas. Recently, techniques have been proposed for this purpose mainly based on the concept of the traffic light. This system provides a tool to decide the level of stimulation rate based on the real-time analysis of the induced seismicity and the ongoing ground motion values. However, in some cases the induced effect can be delayed with respect to the time when the reservoir is stimulated. Thus, a controlling system technique able to estimate the ground motion levels for different time scales can help to better control the geothermal system. Here we present an adaptation of the classical probabilistic seismic hazard analysis to the case where the seismicity rate as well as the propagation medium properties are not constant with time. We use a non-homogeneous seismicity model for modeling purposes, in which the seismicity rate and b-value of the recurrence relationship change with time. Additionally, as a further controlling procedure, we propose a moving time window analysis of the recorded peak ground-motion values aimed at monitoring the changes in the propagation medium. In fact, for the same set of magnitude values recorded at the same stations, we expect that on average peak ground motion values attenuate in same way. As a consequence, the residual differences can be reasonably ascribed to changes in medium properties. These changes can be modeled and directly introduced in the hazard integral. We applied the proposed technique to a training dataset of induced earthquakes recorded by Berkeley-Geysers network, which is installed in The Geysers geothermal area in Northern California. The reliability of the techniques is then tested by using a different dataset performing seismic hazard analysis in a time-evolving approach, which provides with ground-motion values having fixed probabilities of exceedence. Those values can be finally compared with the observations by using appropriate statistical tests.

Using finite-difference waveform modeling to better understand rupture kinematics and path effects in ground motion modeling: an induced seismicity case study at the Groningen Gas field

NASA Astrophysics Data System (ADS)

Zurek, B.; Burnett, W. A.; deMartin, B.

2017-12-01

Ground motion models (GMMs) have historically been used as input in the development of probabilistic seismic hazard analysis (PSHA) and as an engineering tool to assess risk in building design. Generally these equations are developed from empirical analysis of observations that come from fairly complete catalogs of seismic events. One of the challenges when doing a PSHA analysis in a region where earthquakes are anthropogenically induced is that the catalog of observations is not complete enough to come up with a set of equations to cover all expected outcomes. For example, PSHA analysis at the Groningen gas field, an area of known induced seismicity, requires estimates of ground motions from tremors up to a maximum magnitude of 6.5 ML. Of the roughly 1300 recordable earthquakes the maximum observed magnitude to date has been 3.6ML. This paper is part of a broader study where we use a deterministic finite-difference wave-form modeling tool to compliment the traditional development of GMMs. Of particular interest is the sensitivity of the GMM's to uncertainty in the rupture process and how this scales to larger magnitude events that have not been observed. A kinematic fault rupture model is introduced to our waveform simulations to test the sensitivity of the GMMs to variability in the fault rupture process that is physically consistent with observations. These tests will aid in constraining the degree of variability in modeled ground motions due to a realistic range of fault parameters and properties. From this study it is our conclusion that in order to properly capture the uncertainty of the GMMs with magnitude up-scaling one needs to address the impact of uncertainty in the near field (<10km) imposed by the lack of constraint on the finite rupture model. By quantifying the uncertainty back to physical principles it is our belief that it can be better constrained and thus reduce exposure to risk. Further, by investigating and constraining the range of fault rupture scenarios and earthquake magnitudes on ground motion models, hazard and risk analysis in regions with incomplete earthquake catalogs, such as the Groningen gas field, can be better understood.

Verifying a computational method for predicting extreme ground motion

USGS Publications Warehouse

Harris, R.A.; Barall, M.; Andrews, D.J.; Duan, B.; Ma, S.; Dunham, E.M.; Gabriel, A.-A.; Kaneko, Y.; Kase, Y.; Aagaard, Brad T.; Oglesby, D.D.; Ampuero, J.-P.; Hanks, T.C.; Abrahamson, N.

2011-01-01

In situations where seismological data is rare or nonexistent, computer simulations may be used to predict ground motions caused by future earthquakes. This is particularly practical in the case of extreme ground motions, where engineers of special buildings may need to design for an event that has not been historically observed but which may occur in the far-distant future. Once the simulations have been performed, however, they still need to be tested. The SCEC-USGS dynamic rupture code verification exercise provides a testing mechanism for simulations that involve spontaneous earthquake rupture. We have performed this examination for the specific computer code that was used to predict maximum possible ground motion near Yucca Mountain. Our SCEC-USGS group exercises have demonstrated that the specific computer code that was used for the Yucca Mountain simulations produces similar results to those produced by other computer codes when tackling the same science problem. We also found that the 3D ground motion simulations produced smaller ground motions than the 2D simulations.

Validation of attenuation models for ground motion applications in central and eastern North America

DOE PAGES

Pasyanos, Michael E.

2015-11-01

Recently developed attenuation models are incorporated into standard one-dimensional (1-D) ground motion prediction equations (GMPEs), effectively making them two-dimensional (2-D) and eliminating the need to create different GMPEs for an increasing number of sub-regions. The model is tested against a data set of over 10,000 recordings from 81 earthquakes in North America. The use of attenuation models in GMPEs improves our ability to fit observed ground motions and should be incorporated into future national hazard maps. The improvement is most significant at higher frequencies and longer distances which have a greater number of wave cycles. This has implications for themore » rare high-magnitude earthquakes, which produce potentially damaging ground motions over wide areas, and drive the seismic hazards. Furthermore, the attenuation models can be created using weak ground motions, they could be developed for regions of low seismicity where empirical recordings of ground motions are uncommon and do not span the full range of magnitudes and distances.« less

Examining Rotational Ground Motion Induced by Tornados

NASA Astrophysics Data System (ADS)

Kessler, Elijah; Dunn, Robert

2016-03-01

Ring lasers are well known for their ability to detect rotation and to serve as replacements for mechanical gyroscopes. The sensitivity of large ring lasers to various forms of ground motion is less familiar. Since ring lasers preferentially measure rotational ground motion and a standard seismograph is designed to measure translational and vertical ground motion, each device responds to different aspects of ground movement. Therefore, the two instruments will be used to explore responses to microseisms, earthquake generated shear waves, and in particular tornado generated ground movement. On April 27, 2014 an EF4 tornado devastated Vilonia, AR a small town ~ 21 km from the Hendrix College ring laser. The proximity of the tornado's path to the ring laser interferometer and to a seismograph located in Vilonia provided the opportunity to examine the response of these instruments to tornadic generated ground motion. Our measurements suggest tornadic weather systems can produce both rotational and lateral ground motion. This contention is supported by an after the fact damage survey which found that the tornado flattened a forest in which trees were uprooted and laid down in a pair of converging arcs with the centerline pointed in the direction of the tornado's path.

Predicting the seismic performance of typical R/C healthcare facilities: emphasis on hospitals

NASA Astrophysics Data System (ADS)

Bilgin, Huseyin; Frangu, Idlir

2017-09-01

Reinforced concrete (RC) type of buildings constitutes an important part of the current building stock in earthquake prone countries such as Albania. Seismic response of structures during a severe earthquake plays a vital role in the extent of structural damage and resulting injuries and losses. In this context, this study evaluates the expected performance of a five-story RC healthcare facility, representative of common practice in Albania, designed according to older codes. The design was based on the code requirements used in this region during the mid-1980s. Non-linear static and dynamic time history analyses were conducted on the structural model using the Zeus NL computer program. The dynamic time history analysis was conducted with a set of ground motions from real earthquakes. The building responses were estimated in global levels. FEMA 356 criteria were used to predict the seismic performance of the building. The structural response measures such as capacity curve and inter-story drift under the set of ground motions and pushover analyses results were compared and detailed seismic performance assessment was done. The main aim of this study is considering the application and methodology for the earthquake performance assessment of existing buildings. The seismic performance of the structural model varied significantly under different ground motions. Results indicate that case study building exhibit inadequate seismic performance under different seismic excitations. In addition, reasons for the poor performance of the building is discussed.

Performance of Irikura's Recipe Rupture Model Generator in Earthquake Ground Motion Simulations as Implemented in the Graves and Pitarka Hybrid Approach.

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

Pitarka, A.

We analyzed the performance of the Irikura and Miyake (2011) (IM2011) asperity-­ based kinematic rupture model generator, as implemented in the hybrid broadband ground-­motion simulation methodology of Graves and Pitarka (2010), for simulating ground motion from crustal earthquakes of intermediate size. The primary objective of our study is to investigate the transportability of IM2011 into the framework used by the Southern California Earthquake Center broadband simulation platform. In our analysis, we performed broadband (0 -­ 20Hz) ground motion simulations for a suite of M6.7 crustal scenario earthquakes in a hard rock seismic velocity structure using rupture models produced with bothmore » IM2011 and the rupture generation method of Graves and Pitarka (2016) (GP2016). The level of simulated ground motions for the two approaches compare favorably with median estimates obtained from the 2014 Next Generation Attenuation-­West2 Project (NGA-­West2) ground-­motion prediction equations (GMPEs) over the frequency band 0.1–10 Hz and for distances out to 22 km from the fault. We also found that, compared to GP2016, IM2011 generates ground motion with larger variability, particularly at near-­fault distances (<12km) and at long periods (>1s). For this specific scenario, the largest systematic difference in ground motion level for the two approaches occurs in the period band 1 – 3 sec where the IM2011 motions are about 20 – 30% lower than those for GP2016. We found that increasing the rupture speed by 20% on the asperities in IM2011 produced ground motions in the 1 – 3 second bandwidth that are in much closer agreement with the GMPE medians and similar to those obtained with GP2016. The potential implications of this modification for other rupture mechanisms and magnitudes are not yet fully understood, and this topic is the subject of ongoing study.« less

Development of Maximum Considered Earthquake Ground Motion Maps

USGS Publications Warehouse

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

2000-01-01

The 1997 NEHRP Recommended Provisions for Seismic Regulations for New Buildings use a design procedure that is based on spectral response acceleration rather than the traditional peak ground acceleration, peak ground velocity, or zone factors. The spectral response accelerations are obtained from maps prepared following the recommendations of the Building Seismic Safety Council's (BSSC) Seismic Design Procedures Group (SDPG). The SDPG-recommended maps, the Maximum Considered Earthquake (MCE) Ground Motion Maps, are based on the U.S. Geological Survey (USGS) probabilistic hazard maps with additional modifications incorporating deterministic ground motions in selected areas and the application of engineering judgement. The MCE ground motion maps included with the 1997 NEHRP Provisions also serve as the basis for the ground motion maps used in the seismic design portions of the 2000 International Building Code and the 2000 International Residential Code. Additionally the design maps prepared for the 1997 NEHRP Provisions, combined with selected USGS probabilistic maps, are used with the 1997 NEHRP Guidelines for the Seismic Rehabilitation of Buildings.

Ground Motion in Central Mexico: A Comprehensive Analysis

NASA Astrophysics Data System (ADS)

Ramirez-Guzman, L.; Juarez, A.; Rábade, S.; Aguirre, J.; Bielak, J.

2015-12-01

This study presents a detailed analysis of the ground motion in Central Mexico based on numerical simulations, as well as broadband and strong ground motion records. We describe and evaluate a velocity model for Central Mexico derived from noise and regional earthquake cross-correlations, which is used throughout this research to estimate the ground motion in the region. The 3D crustal model includes a geotechnical structure of the Valley of Mexico (VM), subduction zone geometry, and 3D velocity distributions. The latter are based on more than 200 low magnitude (Mw < 4.5) earthquakes and two years of noise recordings. We emphasize the analysis on the ground motion in the Valley of Mexico originating from intra-slab deep events and temblors located along the Pacific coast. Also, we quantify the effects Trans-Mexican Volcanic Belt (TMVB) and the low-velocity deposits on the ground motion. The 3D octree-based finite element wave propagation computations, valid up to 1 Hz, reveal that the inclusion of a basin with a structure as complex as the Valley of Mexico dramatically enhances the regional effects induced by the TMVB. Moreover, the basin not only produces ground motion amplification and anomalous duration, but it also favors the energy focusing into zones of Mexico City where structures typically undergo high levels of damage.

A flatfile of ground motion intensity measurements from induced earthquakes in Oklahoma and Kansas

USGS Publications Warehouse

Rennolet, Steven B.; Moschetti, Morgan P.; Thompson, Eric M.; Yeck, William

2018-01-01

We have produced a uniformly processed database of orientation-independent (RotD50, RotD100) ground motion intensity measurements containing peak horizontal ground motions (accelerations and velocities) and 5-percent-damped pseudospectral accelerations (0.1–10 s) from more than 3,800 M ≥ 3 earthquakes in Oklahoma and Kansas that occurred between January 2009 and December 2016. Ground motion time series were collected from regional, national, and temporary seismic arrays out to 500 km. We relocated the majority of the earthquake hypocenters using a multiple-event relocation algorithm to produce a set of near-uniformly processed hypocentral locations. Ground motion processing followed standard methods, with the primary objective of reducing the effects of noise on the measurements. Regional wave-propagation features and the high seismicity rate required careful selection of signal windows to ensure that we captured the entire ground motion record and that contaminating signals from extraneous earthquakes did not contribute to the database. Processing was carried out with an automated scheme and resulted in a database comprising more than 174,000 records (https://dx.doi.org/10.5066/F73B5X8N). We anticipate that these results will be useful for improved understanding of earthquake ground motions and for seismic hazard applications.

Ground Motion Modeling in the Eastern Caucasus

DOE PAGES

Pitarka, Arben; Gok, Rengin; Yetirmishli, Gurban; ...

2016-05-13

In this paper, we analyzed the performance of a preliminary three-dimensional (3D) velocity model of the Eastern Caucasus covering most of the Azerbaijan. The model was developed in support to long-period ground motion simulations and seismic hazard assessment from regional earthquakes in Azerbaijan. The model’s performance was investigated by simulating ground motion from the damaging Mw 5.9, 2012 Zaqatala earthquake, which was well recorded throughout the region by broadband seismic instruments. In our simulations, we use a parallelized finite-difference method of fourth-order accuracy. The comparison between the simulated and recorded ground motion velocity in the modeled period range of 3–20more » s shows that in general, the 3D velocity model performs well. Areas in which the model needs improvements are located mainly in the central part of the Kura basin and in the Caspian Sea coastal areas. Comparisons of simulated ground motion using our 3D velocity model and corresponding 1D regional velocity model were used to locate areas with strong 3D wave propagation effects. In areas with complex underground structure, the 1D model fails to produce the observed ground motion amplitude and duration, and spatial extend of ground motion amplification caused by wave propagation effects.« less

Using a Full Complex Site Transfer Function to Estimate Strong Ground Motion in Port-au-Prince (Haiti).

NASA Astrophysics Data System (ADS)

ST Fleur, S.; Courboulex, F.; Bertrand, E.; Mercier De Lepinay, B. F.; Hough, S. E.; Boisson, D.; Momplaisir, R.

2017-12-01

To assess the possible impact of a future earthquake in the urban area of Port-au-Prince (Haiti), we have implemented a simulation approach for complex ground motions produced by an earthquake. To this end, we have integrated local site effect in the prediction of strong ground motions in Port-au-Prince using the complex transfer functions method, which takes into account amplitude changes as well as phase changes. This technique is particularly suitable for basins where a conventional 1D digital approach proves inadequate, as is the case in Port-au-Prince. To do this, we use the results of the Standard Spectral Ratio (SSR) approach of St Fleur et al. (2016) to estimate the amplitude of the response of the site to a nearby rock site. Then, we determine the phase difference between sites, interpreted as changes in the phase of the signal related to local site conditions, using the signals of the 2010 earthquake aftershocks records. Finally, the accelerogram of the simulated earthquake is obtain using the technique of the inverse Fourier transform. The results of this study showed that the strongest soil motions are expected in neighborhoods of downtown Port-au-Prince and adjacent hills. In addition, this simulation method by complex transfer functions was validated by comparison with recorded actual data. Our simulated response spectra reproduce very well both the amplitude and the shape of the response spectra of recorded earthquakes. This new approach allowed to reproduce the lengthening of the signal that could be generated by surface waves at certain stations in the city of Port-au-Prince. However, two points of vigilance must be considered: (1) a good signal-to-noise ratio is necessary to obtain a robust estimate of the site-reference phase shift (ratio at least equal to 10); (2) unless the amplitude and phase changes are measured on strong motion records, this technique does not take non-linear effects into account.

Seismic risk assessment for Poiana Uzului (Romania) buttress dam on Uz river

NASA Astrophysics Data System (ADS)

Moldovan, Iren-Adelina; Toma-Danila, Dragos; Paerele, Cosmin Marian; Emilian Toader, Victorin; Petruta Constantin, Angela; Ghita, Cristian

2017-04-01

The most important specific requirements towards dams' safety is the seismic risk assessment. This objective will 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 dams' site, the structures vulnerability and the downstream risk characteristics. The maximum expected values for ground motions at dams' site have been obtained using probabilistic seismic hazard assessment approaches. The structural vulnerability was obtained from dams' characteristics (age, high, water volume) and the downstream risk was assessed using human, economical, touristic, historic and cultural heritage information from the areas that might be flooded in the case of a dam failure. A couple of flooding scenarios have been performed. The results of the work consist of local and regional seismic information, specific characteristics of dam, seismic hazard values for different return periods and risk classes. The studies realized in this paper have as final goal to provide in the near future the local emergency services with warnings of a potential dam failure and ensuing flood as a result of a large earthquake occurrence, allowing further public training for evacuation. Acknowledgments This work was partially supported by the Partnership in Priority Areas Program - PNII, under MEN-UEFISCDI, DARING Project no. 69/2014 and the Nucleu Program - PN 16-35, Project no. 03 01 and 01 06.

Radar Observation of Insects - Mosquitoes

NASA Technical Reports Server (NTRS)

Frost, E.; Downing, J.

1979-01-01

Tests were conducted at several sites over the coastal lowlands of New Jersey and over a region of high plains and low mountains in Oklahoma. In one area, a salt marsh in New Jersey, extensive ground tests were combined with laboratory data on expected insect backscatter to arrive at an extremely convincing model of the insect origin of most Dot Angels. A great deal of insight was studied from radar on the buildup and dispersal of insect swarms, since radar can follow where other means of trapping and observation cannot. Data on large-scale behavior as a function of wind and topography are presented. Displayed techniques which show individual or small swarm motion within some larger cloud or mass, or which can show the overall motion over great distances were developed. The influence of wind and terrain on insect motion and dispersal is determined from radar data.

To fly or not to fly? The automatic influence of negation on language-space associations.

PubMed

Dudschig, Carolin; de la Vega, Irmgard; Kaup, Barbara

2015-09-01

Embodied models of language understanding propose a close association between language comprehension and sensorimotor processes. Specifically, they suggest that meaning representation is grounded in modal experiences. Converging evidence suggests that words automatically activate spatial processing. For example, words such as 'sky' ('ground') facilitate motor and visual processing associated with upper (lower) space. However, very little is known regarding the influence of linguistic operators such as negation on these language-space associations. If these associations play a crucial role for language understanding beyond the word level, one would expect linguistic operators to automatically influence or modify these language-space associations. Participants read sentences describing an event implying an upward or a downward motion in an affirmative or negated version (e.g. The granny looks to the sky/ground vs. The granny does not look to the sky/ground). Subsequently, participants responded with an upward or downward arm movement according to the colour of a dot on the screen. The results showed that the motion direction implied in the sentences influenced subsequent spatially directed motor responses. For affirmative sentences, arm movements were faster if they matched the movement direction implied in the sentence. This language-space association was modified by the negation operator. Our results show that linguistic operators--such as negation--automatically modify language-space associations. Thus, language-space associations seem to reflect language processes beyond pure word-based activations.

What do data used to develop ground-motion prediction equations tell us about motions near faults?

USGS Publications Warehouse

Boore, David M.

2014-01-01

A large database of ground motions from shallow earthquakes occurring in active tectonic regions around the world, recently developed in the Pacific Earthquake Engineering Center’s NGA-West2 project, has been used to investigate what such a database can say about the properties and processes of crustal fault zones. There are a relatively small number of near-rupture records, implying that few recordings in the database are within crustal fault zones, but the records that do exist emphasize the complexity of ground-motion amplitudes and polarization close to individual faults. On average over the whole data set, however, the scaling of ground motions with magnitude at a fixed distance, and the distance dependence of the ground motions, seem to be largely consistent with simple seismological models of source scaling, path propagation effects, and local site amplification. The data show that ground motions close to large faults, as measured by elastic response spectra, tend to saturate and become essentially constant for short periods. This saturation seems to be primarily a geometrical effect, due to the increasing size of the rupture surface with magnitude, and not due to a breakdown in self similarity.

What Do Data Used to Develop Ground-Motion Prediction Equations Tell Us About Motions Near Faults?

NASA Astrophysics Data System (ADS)

Boore, David M.

2014-11-01

A large database of ground motions from shallow earthquakes occurring in active tectonic regions around the world, recently developed in the Pacific Earthquake Engineering Center's NGA-West2 project, has been used to investigate what such a database can say about the properties and processes of crustal fault zones. There are a relatively small number of near-rupture records, implying that few recordings in the database are within crustal fault zones, but the records that do exist emphasize the complexity of ground-motion amplitudes and polarization close to individual faults. On average over the whole data set, however, the scaling of ground motions with magnitude at a fixed distance, and the distance dependence of the ground motions, seem to be largely consistent with simple seismological models of source scaling, path propagation effects, and local site amplification. The data show that ground motions close to large faults, as measured by elastic response spectra, tend to saturate and become essentially constant for short periods. This saturation seems to be primarily a geometrical effect, due to the increasing size of the rupture surface with magnitude, and not due to a breakdown in self similarity.

A synthetic GMPE based on deterministic simulated ground motion data obtained from dynamic rupture models

NASA Astrophysics Data System (ADS)

Dalguer, L. A.; Baumann, C.; Cauzzi, C.

2013-12-01

Empirical ground motion prediction in the very near-field and for large magnitudes is often based on extrapolation of ground motion prediction equations (GMPEs) outside the range where they are well constrained by recorded data. With empirical GMPEs it is also difficult to capture source-dominated ground motion patterns, such as the effects of velocity pulses induced by subshear and supershear rupture directivity, buried and surface-rupturing, hanging-wall and foot-wall, weak shallow layers, complex geometry faults and stress drop. A way to cope at least in part with these shortcomings is to augment the calibration datasets with synthetic ground motions. To this aim, physics-based dynamic rupture models - where the physical bases involved in the fault rupture are explicitly considered - appear to be a suitable approach to produce synthetic ground motions. In this contribution, we first perform an assessment of a database of synthetic ground motions generated by a suite of dynamic rupture simulations to verify compatibility of the peak ground amplitudes with current GMPEs. The synthetic data-set is composed by 360 earthquake scenarios with moment magnitudes in the range of 5.5-7, for three mechanisms of faulting (reverse, normal and strike-slip) and for both buried faults and surface rupturing faults. Second, we parameterise the synthetic dataset through a GMPE. For this purpose, we identify the basic functional forms by analyzing the variation of the synthetic peak ground motions and spectral ordinates as a function of different explanatory variables related to the earthquake source characteristics, in order to account for some of the source effects listed above. We argue that this study provides basic guidelines for the developments of future GMPEs including data from physics-based numerical simulations.

Analysis of the Source and Ground Motions from the 2017 M8.2 Tehuantepec and M7.1 Puebla Earthquakes

NASA Astrophysics Data System (ADS)

Melgar, D.; Sahakian, V. J.; Perez-Campos, X.; Quintanar, L.; Ramirez-Guzman, L.; Spica, Z.; Espindola, V. H.; Ruiz-Angulo, A.; Cabral-Cano, E.; Baltay, A.; Geng, J.

2017-12-01

The September 2017 Tehuantepec and Puebla earthquakes were intra-slab earthquakes that together caused significant damage in broad regions of Mexico, including the states of Oaxaca, Chiapas, Morelos, Puebla, Mexico, and Mexico City. Ground motions in Mexico City have approximately the same angle of incidence from both earthquakes and potentially sample similar paths close to the city. We examine site effects and source terms by analysis of residuals between Ground-Motion Prediction Equations (GMPEs) and observed ground motions for both of these events at stations from the Servicio Sismólogico Nacional, Instituto de Ingeniería, and the Instituto de Geofísica Red del Valle de Mexico networks. GMPEs are a basis for seismic design, but also provide median ground motion values to act as a basis for comparison of individual earthquakes and site responses. First, we invert for finite-fault slip inversions for Tehuantepec with high-rate GPS, static GPS, tide gauge and DART buoy data, and for Puebla with high-rate GPS and strong motion data. Using the distance from the stations with ground motion observations to the derived slip models, we use the GMPEs of Garcia et al. (2005), Zhao et al. (2006), and Abrahamson, Silva and Kamai (2014), to compute predicted values of peak ground acceleration and velocity (PGA and PGV) and response spectral accelerations (SA). Residuals between observed and predicted ground motion parameters are then computed for each recording, and are decomposed into event and site components using a mixed effects regression. We analyze these residuals as an adjustment away from median ground motions in the region to glean information about the earthquake source properties, as well as local site response in and outside of the Mexico City basin. The event and site terms are then compared with available values of stress drop for the two earthquakes, and Vs30 values for the sites, respectively. This analysis is useful in determining which GMPE is most appropriate in the central Mexico region, important for future ground motion studies and rapid response products such as ShakeMap.

Ground motions from induced earthquakes in Oklahoma and Kansas and the implications for seismic hazard

NASA Astrophysics Data System (ADS)

Moschetti, M. P.; Rennolet, S.; Thompson, E.; Yeck, W.; McNamara, D. E.; Herrmann, R. B.; Powers, P.; Hoover, S. M.

2016-12-01

Recent efforts to characterize the seismic hazard resulting from increased seismicity rates in Oklahoma and Kansas highlight the need for a regionalized ground motion characterization. To support these efforts, we measure and compile strong ground motions and compare these average ground motions intensity measures (IMs) with existing ground motion prediction equations (GMPEs). IMs are computed for available broadband and strong-motion records from M≥3 earthquakes occurring January 2009-April 2016, using standard strong motion processing guidelines. We verified our methods by comparing results from specific earthquakes to other standard procedures such as the USGS Shakemap system. The large number of records required an automated processing scheme, which was complicated by the extremely high rate of small-magnitude earthquakes 2014-2016. Orientation-independent IMs include peak ground motions (acceleration and velocity) and pseudo-spectral accelerations (5 percent damping, 0.1-10 s period). Metadata for the records included relocated event hypocenters. The database includes more than 160,000 records from about 3200 earthquakes. Estimates of the mean and standard deviation of the IMs are computed by distance binning at intervals of 2 km. Mean IMs exhibit a clear break in geometrical attenuation at epicentral distances of about 50-70 km, which is consistent with previous studies in the CEUS. Comparisons of these ground motions with modern GMPEs provide some insight into the relative IMs of induced earthquakes in Oklahoma and Kansas relative to the western U.S. and the central and eastern U.S. The site response for these stations is uncertain because very little is known about shallow seismic velocity in the region, and we make no attempt to correct observed IMs to a reference site conditions. At close distances, the observed IMs are lower than the predictions of the seed GMPEs of the NGA-East project (and about consistent with NGA-West-2 ground motions). This ground motion database may be used to inform future seismic hazard forecast models and in the development of regionally appropriate GMPEs.

Source Model of the MJMA 6.5 Plate-Boundary Earthquake at the Nankai Trough, Southwest Japan, on April 1, 2016, Based on Strong Motion Waveform Modeling

NASA Astrophysics Data System (ADS)

Asano, K.

2017-12-01

An MJMA 6.5 earthquake occurred offshore the Kii peninsula, southwest Japan on April 1, 2016. This event was interpreted as a thrust-event on the plate-boundary along the Nankai trough where (Wallace et al., 2016). This event is the largest plate-boundary earthquake in the source region of the 1944 Tonankai earthquake (MW 8.0) after that event. The significant point of this event regarding to seismic observation is that this event occurred beneath an ocean-bottom seismic network called DONET1, which is jointly operated by NIED and JAMSTEC. Since moderate-to-large earthquake of this focal type is very rare in this region in the last half century, it is a good opportunity to investigate the source characteristics relating to strong motion generation of subduction-zone plate-boundary earthquakes along the Nankai trough. Knowledge obtained from the study of this earthquake would contribute to ground motion prediction and seismic hazard assessment for future megathrust earthquakes expected in the Nankai trough. In this study, the source model of the 2016 offshore the Kii peninsula earthquake was estimated by broadband strong motion waveform modeling using the empirical Green's function method (Irikura, 1986). The source model is characterized by strong motion generation area (SMGA) (Miyake et al., 2003), which is defined as a rectangular area with high-stress drop or high slip-velocity. SMGA source model based on the empirical Green's function method has great potential to reproduce ground motion time history in broadband frequency range. We used strong motion data from offshore stations (DONET1 and LTBMS) and onshore stations (NIED F-net and DPRI). The records of an MJMA 3.2 aftershock at 13:04 on April 1, 2016 were selected for the empirical Green's functions. The source parameters of SMGA are optimized by the waveform modeling in the frequency range 0.4-10 Hz. The best estimate of SMGA size is 19.4 km2, and SMGA of this event does not follow the source scaling relationship for past plate-boundary earthquakes along the Japan trench, northeast Japan. This finding implies that the source characteristics of plate-boundary events in the Nankai trough are different from those in the Japan Trench, and it could be important information to consider regional variation in ground motion prediction.

Spectral element modelling of seismic wave propagation in visco-elastoplastic media including excess-pore pressure development

NASA Astrophysics Data System (ADS)

Oral, Elif; Gélis, Céline; Bonilla, Luis Fabián; Delavaud, Elise

2017-12-01

Numerical modelling of seismic wave propagation, considering soil nonlinearity, has become a major topic in seismic hazard studies when strong shaking is involved under particular soil conditions. Indeed, when strong ground motion propagates in saturated soils, pore pressure is another important parameter to take into account when successive phases of contractive and dilatant soil behaviour are expected. Here, we model 1-D seismic wave propagation in linear and nonlinear media using the spectral element numerical method. The study uses a three-component (3C) nonlinear rheology and includes pore-pressure excess. The 1-D-3C model is used to study the 1987 Superstition Hills earthquake (ML 6.6), which was recorded at the Wildlife Refuge Liquefaction Array, USA. The data of this event present strong soil nonlinearity involving pore-pressure effects. The ground motion is numerically modelled for different assumptions on soil rheology and input motion (1C versus 3C), using the recorded borehole signals as input motion. The computed acceleration-time histories show low-frequency amplification and strong high-frequency damping due to the development of pore pressure in one of the soil layers. Furthermore, the soil is found to be more nonlinear and more dilatant under triaxial loading compared to the classical 1C analysis, and significant differences in surface displacements are observed between the 1C and 3C approaches. This study contributes to identify and understand the dominant phenomena occurring in superficial layers, depending on local soil properties and input motions, conditions relevant for site-specific studies.

An event database for rotational seismology

NASA Astrophysics Data System (ADS)

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

2016-04-01

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

Long-period Ground Motion Simulation in the Osaka Basin during the 2011 Great Tohoku Earthquake

NASA Astrophysics Data System (ADS)

Iwata, T.; Kubo, H.; Asano, K.; Sato, K.; Aoi, S.

2014-12-01

Large amplitude long-period ground motions (1-10s) with long duration were observed in the Osaka sedimentary basin during the 2011 Tohoku earthquake (Mw9.0) and its aftershock (Ibaraki-Oki, Mw7.7), which is about 600 km away from the source regions. Sato et al. (2013) analyzed strong ground motion records from the source region to the Osaka basin and showed the following characteristics. (1) In the period range of 1 to 10s, the amplitude of horizontal components of the ground motion at the site-specific period is amplified in the Osaka basin sites. The predominant period is about 7s in the bay area where the largest pSv were observed. (2) The velocity Fourier amplitude spectra with their predominant period of around 7s are observed at the bedrock sites surrounding the Osaka basin. Those characteristics were observed during both of the mainshock and the largest aftershock. Therefore, large long-period ground motions in the Osaka basin are generated by the combination of propagation-path and basin effects. They simulated ground motions due to the largest aftershock as a simple point source model using three-dimensional FDM (GMS; Aoi and Fujiwara, 1999). They used a three-dimensional velocity structure based on the Japan Integrated Velocity Structure Model (JIVSM, Koketsu et al., 2012), with the minimum effective period of the computation of 3s. Their simulation result reproduced the observation characteristics well and it validates the applicability of the JIVSM for the long period ground motion simulation. In this study, we try to simulate long-period ground motions during the mainshock. The source model we used for the simulation is based on the SMGA model obtained by Asano and Iwata (2012). We succeed to simulate long-period ground motion propagation from Kanto area to the Osaka basin fairly well. The long-period ground motion simulations with the several Osaka basin velocity structure models are done for improving the model applicability. We used strong motion data recorded by K-NET, KiK-net and F-net of NIED, CEORKA, BRI, JMA, Osaka city waterworks bureau, and Osaka prefecture. GMS provided by NIED is used for the computation.

Performance of Irikura recipe rupture model generator in earthquake ground motion simulations with Graves and Pitarka hybrid approach

USGS Publications Warehouse

Pitarka, Arben; Graves, Robert; Irikura, Kojiro; Miyake, Hiroe; Rodgers, Arthur

2017-01-01

We analyzed the performance of the Irikura and Miyake (Pure and Applied Geophysics 168(2011):85–104, 2011) (IM2011) asperity-based kinematic rupture model generator, as implemented in the hybrid broadband ground motion simulation methodology of Graves and Pitarka (Bulletin of the Seismological Society of America 100(5A):2095–2123, 2010), for simulating ground motion from crustal earthquakes of intermediate size. The primary objective of our study is to investigate the transportability of IM2011 into the framework used by the Southern California Earthquake Center broadband simulation platform. In our analysis, we performed broadband (0–20 Hz) ground motion simulations for a suite of M6.7 crustal scenario earthquakes in a hard rock seismic velocity structure using rupture models produced with both IM2011 and the rupture generation method of Graves and Pitarka (Bulletin of the Seismological Society of America, 2016) (GP2016). The level of simulated ground motions for the two approaches compare favorably with median estimates obtained from the 2014 Next Generation Attenuation-West2 Project (NGA-West2) ground motion prediction equations (GMPEs) over the frequency band 0.1–10 Hz and for distances out to 22 km from the fault. We also found that, compared to GP2016, IM2011 generates ground motion with larger variability, particularly at near-fault distances (<12 km) and at long periods (>1 s). For this specific scenario, the largest systematic difference in ground motion level for the two approaches occurs in the period band 1–3 s where the IM2011 motions are about 20–30% lower than those for GP2016. We found that increasing the rupture speed by 20% on the asperities in IM2011 produced ground motions in the 1–3 s bandwidth that are in much closer agreement with the GMPE medians and similar to those obtained with GP2016. The potential implications of this modification for other rupture mechanisms and magnitudes are not yet fully understood, and this topic is the subject of ongoing study. We concluded that IM2011 rupture generator performs well in ground motion simulations using Graves and Pitarka hybrid method. Therefore, we recommend it to be considered for inclusion into the framework used by the Southern California Earthquake Center broadband simulation platform.

Performance of Irikura Recipe Rupture Model Generator in Earthquake Ground Motion Simulations with Graves and Pitarka Hybrid Approach

NASA Astrophysics Data System (ADS)

Pitarka, Arben; Graves, Robert; Irikura, Kojiro; Miyake, Hiroe; Rodgers, Arthur

2017-09-01

We analyzed the performance of the Irikura and Miyake (Pure and Applied Geophysics 168(2011):85-104, 2011) (IM2011) asperity-based kinematic rupture model generator, as implemented in the hybrid broadband ground motion simulation methodology of Graves and Pitarka (Bulletin of the Seismological Society of America 100(5A):2095-2123, 2010), for simulating ground motion from crustal earthquakes of intermediate size. The primary objective of our study is to investigate the transportability of IM2011 into the framework used by the Southern California Earthquake Center broadband simulation platform. In our analysis, we performed broadband (0-20 Hz) ground motion simulations for a suite of M6.7 crustal scenario earthquakes in a hard rock seismic velocity structure using rupture models produced with both IM2011 and the rupture generation method of Graves and Pitarka (Bulletin of the Seismological Society of America, 2016) (GP2016). The level of simulated ground motions for the two approaches compare favorably with median estimates obtained from the 2014 Next Generation Attenuation-West2 Project (NGA-West2) ground motion prediction equations (GMPEs) over the frequency band 0.1-10 Hz and for distances out to 22 km from the fault. We also found that, compared to GP2016, IM2011 generates ground motion with larger variability, particularly at near-fault distances (<12 km) and at long periods (>1 s). For this specific scenario, the largest systematic difference in ground motion level for the two approaches occurs in the period band 1-3 s where the IM2011 motions are about 20-30% lower than those for GP2016. We found that increasing the rupture speed by 20% on the asperities in IM2011 produced ground motions in the 1-3 s bandwidth that are in much closer agreement with the GMPE medians and similar to those obtained with GP2016. The potential implications of this modification for other rupture mechanisms and magnitudes are not yet fully understood, and this topic is the subject of ongoing study. We concluded that IM2011 rupture generator performs well in ground motion simulations using Graves and Pitarka hybrid method. Therefore, we recommend it to be considered for inclusion into the framework used by the Southern California Earthquake Center broadband simulation platform.

Strong correlation between stress drop and peak ground acceleration for recent M1–4 earthquakes in the San Francisco Bay Area

DOE PAGES

Trugman, Daniel Taylor; Shearer, Peter M.

2018-03-06

Theoretical and observational studies suggest that between-event variability in the median ground motions of larger ( M≥5 ) earthquakes is controlled primarily by the dynamic properties of the earthquake source, such as Brune-type stress drop. Analogous results remain equivocal for smaller events due to the lack of comprehensive and overlapping ground-motion and source-parameter datasets in this regime. Here in this paper, we investigate the relationship between peak ground acceleration (PGA) and dynamic stress drop for a new dataset of 5297 earthquakes that occurred in the San Francisco Bay area from 2002 through 2016. For each event, we measure PGA onmore » horizontal-component channels of stations within 100 km and estimate stress drop from P-wave spectra recorded on vertical-component channels of the same stations. We then develop a nonparametric ground-motion prediction equation (GMPE) applicable for the moderate (M 1–4) earthquakes in our study region, using a mixed-effects generalization of the Random Forest algorithm. We use the Random Forest GMPE to model the joint influence of magnitude, distance, and near-site effects on observed PGA. We observe a strong correlation between dynamic stress drop and the residual PGA of each event, with the events with higher-than-expected PGA associated with higher values of stress drop. The strength of this correlation increases as a function of magnitude but remains significant even for smaller magnitude events with corner frequencies that approach the observable bandwidth of the acceleration records. Mainshock events are characterized by systematically higher stress drop and PGA than aftershocks of equivalent magnitude. Coherent local variations in the distribution of dynamic stress drop provide observational constraints to support the future development of nonergodic GMPEs that account for variations in median stress drop at different source locations.« less

Strong correlation between stress drop and peak ground acceleration for recent M1–4 earthquakes in the San Francisco Bay Area

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

Trugman, Daniel Taylor; Shearer, Peter M.

Theoretical and observational studies suggest that between-event variability in the median ground motions of larger ( M≥5 ) earthquakes is controlled primarily by the dynamic properties of the earthquake source, such as Brune-type stress drop. Analogous results remain equivocal for smaller events due to the lack of comprehensive and overlapping ground-motion and source-parameter datasets in this regime. Here in this paper, we investigate the relationship between peak ground acceleration (PGA) and dynamic stress drop for a new dataset of 5297 earthquakes that occurred in the San Francisco Bay area from 2002 through 2016. For each event, we measure PGA onmore » horizontal-component channels of stations within 100 km and estimate stress drop from P-wave spectra recorded on vertical-component channels of the same stations. We then develop a nonparametric ground-motion prediction equation (GMPE) applicable for the moderate (M 1–4) earthquakes in our study region, using a mixed-effects generalization of the Random Forest algorithm. We use the Random Forest GMPE to model the joint influence of magnitude, distance, and near-site effects on observed PGA. We observe a strong correlation between dynamic stress drop and the residual PGA of each event, with the events with higher-than-expected PGA associated with higher values of stress drop. The strength of this correlation increases as a function of magnitude but remains significant even for smaller magnitude events with corner frequencies that approach the observable bandwidth of the acceleration records. Mainshock events are characterized by systematically higher stress drop and PGA than aftershocks of equivalent magnitude. Coherent local variations in the distribution of dynamic stress drop provide observational constraints to support the future development of nonergodic GMPEs that account for variations in median stress drop at different source locations.« less

Response of pendulums to complex input ground motion

USGS Publications Warehouse

Graizer, V.; Kalkan, E.

2008-01-01

Dynamic response of most seismological instruments and many engineering structures to ground shaking can be represented via response of a pendulum (single-degree-of-freedom oscillator). In most studies, pendulum response is simplified by considering the input from uni-axial translational motion alone. Complete ground motion however, includes not only translational components but also rotations (tilt and torsion). In this paper, complete equations of motion for three following types of pendulum are described: (i) conventional (mass-on-rod), (ii) mass-on-spring type, and (iii) inverted (astatic), then their response sensitivities to each component of complex ground motion are examined. The results of this study show that a horizontal pendulum similar to an accelerometer used in strong motion measurements is practically sensitive to translational motion and tilt only, while inverted pendulum commonly utilized to idealize multi-degree-of-freedom systems is sensitive not only to translational components, but also to angular accelerations and tilt. For better understanding of the inverted pendulum's dynamic behavior under complex ground excitation, relative contribution of each component of motion on response variants is carefully isolated. The systematically applied loading protocols indicate that vertical component of motion may create time-dependent variations on pendulum's oscillation period; yet most dramatic impact on response is produced by the tilting (rocking) component. ?? 2007 Elsevier Ltd. All rights reserved.

Recovery of Near-Fault Ground Motion by Introducing Rotational Motions

NASA Astrophysics Data System (ADS)

Chiu, H. C.

2014-12-01

Near-fault ground motion is the key data to seismologists for revealing the seismic faulting and earthquake physics and strong-motion data is the only near-fault seismogram that can keep on-scale recording in a major earthquake. Unfortunately, this type of data might be contaminated by the rotation induced effects such as the centrifugal acceleration and the gravity effects. We analyze these effects based on a set of collocated rotation-translation data of small to moderate earthquakes. Results show these rotation effects could be negligible in small ground motion, but they might have a radical growing in the near-fault/extremely large ground motions. In order to extract more information from near-fault seismogram for improving our understating of seismic faulting and earthquake physics, it requires six-component collocated rotation-translation records to reduce or remove these effects.

Application of nonlinear adaptive motion washout to transport ground-handling simulation

NASA Technical Reports Server (NTRS)

Parrish, R. V.; Martin, D. J., Jr.

1983-01-01

The application of a nonlinear coordinated adaptive motion washout to the transport ground-handling environment is documented. Additions to both the aircraft math model and the motion washout system are discussed. The additions to the simulated-aircraft math model provided improved modeling fidelity for braking and reverse-thrust application, and the additions to the motion-base washout system allowed transition from the desired flight parameters to the less restrictive ground parameters of the washout.

Probabilistic seismic hazard assessment for the effect of vertical ground motions on seismic response of highway bridges

NASA Astrophysics Data System (ADS)

Yilmaz, Zeynep

Typically, the vertical component of the ground motion is not considered explicitly in seismic design of bridges, but in some cases the vertical component can have a significant effect on the structural response. The key question of when the vertical component should be incorporated in design is answered by the probabilistic seismic hazard assessment study incorporating the probabilistic seismic demand models and ground motion models. Nonlinear simulation models with varying configurations of an existing bridge in California were considered in the analytical study. The simulation models were subjected to the set of selected ground motions in two stages: at first, only horizontal components of the motion were applied; while in the second stage the structures were subjected to both horizontal and vertical components applied simultaneously and the ground motions that produced the largest adverse effects on the bridge system were identified. Moment demand in the mid-span and at the support of the longitudinal girder and the axial force demand in the column are found to be significantly affected by the vertical excitations. These response parameters can be modeled using simple ground motion parameters such as horizontal spectral acceleration and vertical spectral acceleration within 5% to 30% error margin depending on the type of the parameter and the period of the structure. For a complete hazard assessment, both of these ground motion parameters explaining the structural behavior should also be modeled. For the horizontal spectral acceleration, Abrahamson and Silva (2008) model was used within many available standard model. A new NGA vertical ground motion model consistent with the horizontal model was constructed. These models are combined in a vector probabilistic seismic hazard analyses. Series of hazard curves developed and presented for different locations in Bay Area for soil site conditions to provide a roadmap for the prediction of these features for future earthquakes. Findings from this study will contribute to the development of revised guidelines to address vertical ground motion effects, particularly in the near fault regions, in the seismic design of highway bridges.

Should ground-motion records be rotated to fault-normal/parallel or maximum direction for response history analysis of buildings?

USGS Publications Warehouse

Reyes, Juan C.; Kalkan, Erol

2012-01-01

In the United States, regulatory seismic codes (for example, California Building Code) require at least two sets of horizontal ground-motion components for three-dimensional (3D) response history analysis (RHA) of building structures. For sites within 5 kilometers (3.1 miles) of an active fault, these records should be rotated to fault-normal and fault-parallel (FN/FP) directions, and two RHAs should be performed separately—when FN and then FP direction are aligned with transverse direction of the building axes. This approach is assumed to lead to two sets of responses that envelope the range of possible responses over all nonredundant rotation angles. The validity of this assumption is examined here using 3D computer models of single-story structures having symmetric (torsionally stiff) and asymmetric (torsionally flexible) layouts subjected to an ensemble of near-fault ground motions with and without apparent velocity pulses. In this parametric study, the elastic vibration period is varied from 0.2 to 5 seconds, and yield-strength reduction factors, R, are varied from a value that leads to linear-elastic design to 3 and 5. Further validations are performed using 3D computer models of 9-story structures having symmetric and asymmetric layouts subjected to the same ground-motion set. The influence of the ground-motion rotation angle on several engineering demand parameters (EDPs) is examined in both linear-elastic and nonlinear-inelastic domains to form benchmarks for evaluating the use of the FN/FP directions and also the maximum direction (MD). The MD ground motion is a new definition for horizontal ground motions for use in site-specific ground-motion procedures for seismic design according to provisions of the American Society of Civil Engineers/Seismic Engineering Institute (ASCE/SEI) 7-10. The results of this study have important implications for current practice, suggesting that ground motions rotated to MD or FN/FP directions do not necessarily provide the most critical EDPs in nonlinear-inelastic domain; however, they tend to produce larger EDPs than as-recorded (arbitrarily oriented) motions.

The SCEC Broadband Platform: Open-Source Software for Strong Ground Motion Simulation and Validation

NASA Astrophysics Data System (ADS)

Goulet, C.; Silva, F.; Maechling, P. J.; Callaghan, S.; Jordan, T. H.

2015-12-01

The Southern California Earthquake Center (SCEC) Broadband Platform (BBP) is a carefully integrated collection of open-source scientific software programs that can simulate broadband (0-100Hz) ground motions for earthquakes at regional scales. The BBP scientific software modules implement kinematic rupture generation, low and high-frequency seismogram synthesis using wave propagation through 1D layered velocity structures, seismogram ground motion amplitude calculations, and goodness of fit measurements. These modules are integrated into a software system that provides user-defined, repeatable, calculation of ground motion seismograms, using multiple alternative ground motion simulation methods, and software utilities that can generate plots, charts, and maps. The BBP has been developed over the last five years in a collaborative scientific, engineering, and software development project involving geoscientists, earthquake engineers, graduate students, and SCEC scientific software developers. The BBP can run earthquake rupture and wave propagation modeling software to simulate ground motions for well-observed historical earthquakes and to quantify how well the simulated broadband seismograms match the observed seismograms. The BBP can also run simulations for hypothetical earthquakes. In this case, users input an earthquake location and magnitude description, a list of station locations, and a 1D velocity model for the region of interest, and the BBP software then calculates ground motions for the specified stations. The SCEC BBP software released in 2015 can be compiled and run on recent Linux systems with GNU compilers. It includes 5 simulation methods, 7 simulation regions covering California, Japan, and Eastern North America, the ability to compare simulation results against GMPEs, updated ground motion simulation methods, and a simplified command line user interface.

Regional-specific Stochastic Simulation of Spatially-distributed Ground-motion Time Histories using Wavelet Packet Analysis

NASA Astrophysics Data System (ADS)

Huang, D.; Wang, G.

2014-12-01

Stochastic simulation of spatially distributed ground-motion time histories is important for performance-based earthquake design of geographically distributed systems. In this study, we develop a novel technique to stochastically simulate regionalized ground-motion time histories using wavelet packet analysis. First, a transient acceleration time history is characterized by wavelet-packet parameters proposed by Yamamoto and Baker (2013). The wavelet-packet parameters fully characterize ground-motion time histories in terms of energy content, time- frequency-domain characteristics and time-frequency nonstationarity. This study further investigates the spatial cross-correlations of wavelet-packet parameters based on geostatistical analysis of 1500 regionalized ground motion data from eight well-recorded earthquakes in California, Mexico, Japan and Taiwan. The linear model of coregionalization (LMC) is used to develop a permissible spatial cross-correlation model for each parameter group. The geostatistical analysis of ground-motion data from different regions reveals significant dependence of the LMC structure on regional site conditions, which can be characterized by the correlation range of Vs30 in each region. In general, the spatial correlation and cross-correlation of wavelet-packet parameters are stronger if the site condition is more homogeneous. Using the regional-specific spatial cross-correlation model and cokriging technique, wavelet packet parameters at unmeasured locations can be best estimated, and regionalized ground-motion time histories can be synthesized. Case studies and blind tests demonstrated that the simulated ground motions generally agree well with the actual recorded data, if the influence of regional-site conditions is considered. The developed method has great potential to be used in computational-based seismic analysis and loss estimation in a regional scale.

Predicted Attenuation Relation and Observed Ground Motion of Gorkha Nepal Earthquake of 25 April 2015

NASA Astrophysics Data System (ADS)

Singh, R. P.; Ahmad, R.

2015-12-01

A comparison of recent observed ground motion parameters of recent Gorkha Nepal earthquake of 25 April 2015 (Mw 7.8) with the predicted ground motion parameters using exitsing attenuation relation of the Himalayan region will be presented. The recent earthquake took about 8000 lives and destroyed thousands of poor quality of buildings and the earthquake was felt by millions of people living in Nepal, China, India, Bangladesh, and Bhutan. The knowledge of ground parameters are very important in developing seismic code of seismic prone regions like Himalaya for better design of buildings. The ground parameters recorded in recent earthquake event and aftershocks are compared with attenuation relations for the Himalayan region, the predicted ground motion parameters show good correlation with the observed ground parameters. The results will be of great use to Civil engineers in updating existing building codes in the Himlayan and surrounding regions and also for the evaluation of seismic hazards. The results clearly show that the attenuation relation developed for the Himalayan region should be only used, other attenuation relations based on other regions fail to provide good estimate of observed ground motion parameters.

Engineering uses of physics-based ground motion simulations

USGS Publications Warehouse

Baker, Jack W.; Luco, Nicolas; Abrahamson, Norman A.; Graves, Robert W.; Maechling, Phillip J.; Olsen, Kim B.

2014-01-01

This paper summarizes validation methodologies focused on enabling ground motion simulations to be used with confidence in engineering applications such as seismic hazard analysis and dynmaic analysis of structural and geotechnical systems. Numberical simullation of ground motion from large erthquakes, utilizing physics-based models of earthquake rupture and wave propagation, is an area of active research in the earth science community. Refinement and validatoin of these models require collaboration between earthquake scientists and engineering users, and testing/rating methodolgies for simulated ground motions to be used with confidence in engineering applications. This paper provides an introduction to this field and an overview of current research activities being coordinated by the Souther California Earthquake Center (SCEC). These activities are related both to advancing the science and computational infrastructure needed to produce ground motion simulations, as well as to engineering validation procedures. Current research areas and anticipated future achievements are also discussed.

Beyond SaGMRotI: Conversion to SaArb, SaSN, and SaMaxRot

USGS Publications Warehouse

Watson-Lamprey, J. A.; Boore, D.M.

2007-01-01

In the seismic design of structures, estimates of design forces are usually provided to the engineer in the form of elastic response spectra. Predictive equations for elastic response spectra are derived from empirical recordings of ground motion. The geometric mean of the two orthogonal horizontal components of motion is often used as the response value in these predictive equations, although it is not necessarily the most relevant estimate of forces within the structure. For some applications it is desirable to estimate the response value on a randomly chosen single component of ground motion, and in other applications the maximum response in a single direction is required. We give adjustment factors that allow converting the predictions of geometric-mean ground-motion predictions into either of these other two measures of seismic ground-motion intensity. In addition, we investigate the relation of the strike-normal component of ground motion to the maximum response values. We show that the strike-normal component of ground motion seldom corresponds to the maximum horizontal-component response value (in particular, at distances greater than about 3 km from faults), and that focusing on this case in exclusion of others can result in the underestimation of the maximum component. This research provides estimates of the maximum response value of a single component for all cases, not just near-fault strike-normal components. We provide modification factors that can be used to convert predictions of ground motions in terms of the geometric mean to the maximum spectral acceleration (SaMaxRot) and the random component of spectral acceleration (SaArb). Included are modification factors for both the mean and the aleatory standard deviation of the logarithm of the motions.

Early Site Permit Demonstration Program: Guidelines for determining design basis ground motions. Volume 2, Appendices

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

Not Available

This report develops and applies a methodology for estimating strong earthquake ground motion. The motivation was to develop a much needed tool for use in developing the seismic requirements for structural designs. An earthquake`s ground motion is a function of the earthquake`s magnitude, and the physical properties of the earth through which the seismic waves travel from the earthquake fault to the site of interest. The emphasis of this study is on ground motion estimation in Eastern North America (east of the Rocky Mountains), with particular emphasis on the Eastern United States and southeastern Canada. Eastern North America is amore » stable continental region, having sparse earthquake activity with rare occurrences of large earthquakes. While large earthquakes are of interest for assessing seismic hazard, little data exists from the region to empirically quantify their effects. The focus of the report is on the attributes of ground motion in Eastern North America that are of interest for the design of facilities such as nuclear power plants. This document, Volume II, contains Appendices 2, 3, 5, 6, and 7 covering the following topics: Eastern North American Empirical Ground Motion Data; Examination of Variance of Seismographic Network Data; Soil Amplification and Vertical-to-Horizontal Ratios from Analysis of Strong Motion Data From Active Tectonic Regions; Revision and Calibration of Ou and Herrmann Method; Generalized Ray Procedure for Modeling Ground Motion Attenuation; Crustal Models for Velocity Regionalization; Depth Distribution Models; Development of Generic Site Effects Model; Validation and Comparison of One-Dimensional Site Response Methodologies; Plots of Amplification Factors; Assessment of Coupling Between Vertical & Horizontal Motions in Nonlinear Site Response Analysis; and Modeling of Dynamic Soil Properties.« less

A satellite-tracking millimeter-wave reflector antenna system for mobile satellite-tracking

NASA Technical Reports Server (NTRS)

Densmore, Arthur C. (Inventor); Jamnejad, Vahraz (Inventor); Woo, Kenneth E. (Inventor)

1995-01-01

A miniature dual-band two-way mobile satellite tracking antenna system mounted on a movable ground vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.

Ground motions recorded in Rome during the April 2009 L’Aquila seismic sequence: site response and comparison with ground‐motion predictions based on a global dataset

USGS Publications Warehouse

Caserta, Arrigo; Boore, David; Rovelli, Antonio; Govoni, Aladino; Marra, Fabrizio; Monica, Gieseppe Della; Boschi, Enzo

2013-01-01

The mainshock and moderate‐magnitude aftershocks of the 6 April 2009 M 6.3 L’Aquila seismic sequence, about 90 km northeast of Rome, provided the first earthquake ground‐motion recordings in the urban area of Rome. Before those recordings were obtained, the assessments of the seismic hazard in Rome were based on intensity observations and theoretical considerations. The L’Aquila recordings offer an unprecedented opportunity to calibrate the city response to central Apennine earthquakes—earthquakes that have been responsible for the largest damage to Rome in historical times. Using the data recorded in Rome in April 2009, we show that (1) published theoretical predictions of a 1 s resonance in the Tiber valley are confirmed by observations showing a significant amplitude increase in response spectra at that period, (2) the empirical soil‐transfer functions inferred from spectral ratios are satisfactorily fit through 1D models using the available geological, geophysical, and laboratory data, but local variability can be large for individual events, (3) response spectra for the motions recorded in Rome from the L’Aquila earthquakes are significantly amplified in the radial component at periods near 1 s, even at a firm site on volcanic rocks, and (4) short‐period response spectra are smaller than expected when compared to ground‐motion predictions from equations based on a global dataset, whereas the observed response spectra are higher than expected for periods near 1 s.

Earthquake hazards on the cascadia subduction zone.

PubMed

Heaton, T H; Hartzell, S H

1987-04-10

Large subduction earthquakes on the Cascadia subduction zone pose a potential seismic hazard. Very young oceanic lithosphere (10 million years old) is being subducted beneath North America at a rate of approximately 4 centimeters per year. The Cascadia subduction zone shares many characteristics with subduction zones in southern Chile, southwestern Japan, and Colombia, where comparably young oceanic lithosphere is also subducting. Very large subduction earthquakes, ranging in energy magnitude (M(w)) between 8 and 9.5, have occurred along these other subduction zones. If the Cascadia subduction zone is also storing elastic energy, a sequence of several great earthquakes (M(w) 8) or a giant earthquake (M(w) 9) would be necessary to fill this 1200-kilometer gap. The nature of strong ground motions recorded during subduction earthquakes of M(w) less than 8.2 is discussed. Strong ground motions from even larger earthquakes (M(w) up to 9.5) are estimated by simple simulations. If large subduction earthquakes occur in the Pacific Northwest, relatively strong shaking can be expected over a large region. Such earthquakes may also be accompanied by large local tsunamis.

Seismic cross-coupling noise in torsion pendulums

NASA Astrophysics Data System (ADS)

Shimoda, Tomofumi; Aritomi, Naoki; Shoda, Ayaka; Michimura, Yuta; Ando, Masaki

2018-05-01

Detection of low-frequency gravitational waves around 0.1 Hz is one of the important targets for future gravitational wave observation. One of the main sources of the expected signals is gravitational waves from binary intermediate-mass black hole coalescences which is proposed as one of the formation scenarios of supermassive black holes. By using a torsion pendulum, which can have a resonance frequency of a few millihertz, such signals can be measured on the ground since its rotational motion can act as a free mass down to 0.01 Hz. However, sensitivity of a realistic torsion pendulum will suffer from torsional displacement noise introduced from translational ground motion in the main frequency band of interest. Such noise is called seismic cross-coupling noise, and there has been little research on it. In this paper, systematic investigation is performed to identify routes of cross-coupling transfer for standard torsion pendulums. Based on the results, this paper also proposes reduction schemes of cross-coupling noise, and they were demonstrated experimentally in agreement with theory. This result establishes a basic way to reduce seismic noise in torsion pendulums for the most significant coupling routes.

Tsunami simulation using submarine displacement calculated from simulation of ground motion due to seismic source model

NASA Astrophysics Data System (ADS)

Akiyama, S.; Kawaji, K.; Fujihara, S.

2013-12-01

Since fault fracturing due to an earthquake can simultaneously cause ground motion and tsunami, it is appropriate to evaluate the ground motion and the tsunami by single fault model. However, several source models are used independently in the ground motion simulation or the tsunami simulation, because of difficulty in evaluating both phenomena simultaneously. Many source models for the 2011 off the Pacific coast of Tohoku Earthquake are proposed from the inversion analyses of seismic observations or from those of tsunami observations. Most of these models show the similar features, which large amount of slip is located at the shallower part of fault area near the Japan Trench. This indicates that the ground motion and the tsunami can be evaluated by the single source model. Therefore, we examine the possibility of the tsunami prediction, using the fault model estimated from seismic observation records. In this study, we try to carry out the tsunami simulation using the displacement field of oceanic crustal movements, which is calculated from the ground motion simulation of the 2011 off the Pacific coast of Tohoku Earthquake. We use two fault models by Yoshida et al. (2011), which are based on both the teleseismic body wave and on the strong ground motion records. Although there is the common feature in those fault models, the amount of slip near the Japan trench is lager in the fault model from the strong ground motion records than in that from the teleseismic body wave. First, the large-scale ground motion simulations applying those fault models used by the voxel type finite element method are performed for the whole eastern Japan. The synthetic waveforms computed from the simulations are generally consistent with the observation records of K-NET (Kinoshita (1998)) and KiK-net stations (Aoi et al. (2000)), deployed by the National Research Institute for Earth Science and Disaster Prevention (NIED). Next, the tsunami simulations are performed by the finite difference calculation based on the shallow water theory. The initial wave height for tsunami generation is estimated from the vertical displacement of ocean bottom due to the crustal movements, which is obtained from the ground motion simulation mentioned above. The results of tsunami simulations are compared with the observations of the GPS wave gauges to evaluate the validity for the tsunami prediction using the fault model based on the seismic observation records.

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.

49 CFR 510.9 - Motions to modify, limit, or quash process.

Code of Federal Regulations, 2013 CFR

2013-10-01

... before the return date. Any motion must set forth the grounds and theories of why and how the party... support those grounds and theories. (2) The Deputy Administrator may, upon receiving a motion filed...

49 CFR 510.9 - Motions to modify, limit, or quash process.

Code of Federal Regulations, 2012 CFR

2012-10-01

... before the return date. Any motion must set forth the grounds and theories of why and how the party... support those grounds and theories. (2) The Deputy Administrator may, upon receiving a motion filed...

49 CFR 510.9 - Motions to modify, limit, or quash process.

Code of Federal Regulations, 2014 CFR

2014-10-01

... before the return date. Any motion must set forth the grounds and theories of why and how the party... support those grounds and theories. (2) The Deputy Administrator may, upon receiving a motion filed...

Statistical analysis of low-rise building damage caused by the San Fernando earthquake

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

Scholl, R.E.

1974-02-01

An empirical investigation of damage to low-rise buildings in two selected control areas within Glendale, California, caused by the ground motion precipitated by the San Fernando earthquake of February 9, 1971 is summarized. The procedures for obtaining the appropriate data and the methodology used in deriving ground motion-damage relationships are described. Motion-damage relationships are derived for overall damage and for the most frequently damaged building components. Overall motion-damage relationships are expressed in terms of damage incidence (damage ratio) and damage cost (damage cost factor). The motion-damage relationships derived from the earthquake data are compared with similar data obtained for lou-risemore » buildings subjected to ground motion generated by an underground nuclear explosion. Overall comparison results show that for the same spectral acceleration, the earthquake caused slightly more damage. Differences in ground-motion characteristics for the two types of disturbances provide the most probable explanation for this discrepancy. (auth)« less

Seismic shaking in the North China Basin expected from ruptures of a possible seismic gap

NASA Astrophysics Data System (ADS)

Duan, Benchun; Liu, Dunyu; Yin, An

2017-05-01

A 160 km long seismic gap, which has not been ruptured over 8000 years, was identified recently in North China. In this study, we use a dynamic source model and a newly available high-resolution 3-D velocity structure to simulate long-period ground motion (up to 0.5 Hz) from possibly worst case rupture scenarios of the seismic gap. We find that the characteristics of the earthquake source and the local geologic structure play a critical role in controlling the amplitude and distribution of the simulated strong ground shaking. Rupture directivity and slip asperities can result in large-amplitude (i.e., >1 m/s) ground shaking near the fault, whereas long-duration shaking may occur within sedimentary basins. In particular, a deep and closed Quaternary basin between Beijing and Tianjin can lead to ground shaking of several tens of cm/s for more than 1 min. These results may provide a sound basis for seismic mitigation in one of the most populated regions in the world.

Analysis of strong ground motions and site effects at Kantipath, Kathmandu, from 2015 Mw 7.8 Gorkha, Nepal, earthquake and its aftershocks

NASA Astrophysics Data System (ADS)

Dhakal, Yadab P.; Kubo, Hisahiko; Suzuki, Wataru; Kunugi, Takashi; Aoi, Shin; Fujiwara, Hiroyuki

2016-04-01

Strong ground motions from the 2015 Mw 7.8 Gorkha, Nepal, earthquake and its eight aftershocks recorded by a strong-motion seismograph at Kantipath (KATNP), Kathmandu, were analyzed to assess the ground-motion characteristics and site effects at this location. Remarkably large elastic pseudo-velocity responses exceeding 300 cm/s at 5 % critical damping were calculated for the horizontal components of the mainshock recordings at peak periods of 4-5 s. Conversely, the short-period ground motions of the mainshock were relatively weak despite the proximity of the site to the source fault. The horizontal components of all large-magnitude (Mw ≥ 6.3) aftershock recordings showed peak pseudo-velocity responses at periods of 3-4 s. Ground-motion prediction equations (GMPEs) describing the Nepal Himalaya region have not yet been developed. A comparison of the observational data with GMPEs for Japan showed that with the exception of the peak ground acceleration (PGA) of the mainshock, the observed PGAs and peak ground velocities at the KATNP site are generally well described by the GMPEs for crustal and plate interface events. A comparison of the horizontal-to-vertical ( H/ V) spectral ratios for the S-waves of the mainshock and aftershock recordings suggested that the KATNP site experienced a considerable nonlinear site response, which resulted in the reduced amplitudes of short-period ground motions. The GMPEs were found to underestimate the response values at the peak periods (approximately 4-5 s) of the large-magnitude events. The deep subsurface velocity model of the Kathmandu basin has not been well investigated. Therefore, a one-dimensional velocity model was constructed for the deep sediments beneath the recording station based on an analysis of the H/ V spectral ratios for S-wave coda from aftershock recordings, and it was revealed that the basin sediments strongly amplified the long-period components of the ground motions of the mainshock and large-magnitude aftershocks.

Hazard-to-Risk: High-Performance Computing Simulations of Large Earthquake Ground Motions and Building Damage in the Near-Fault Region

NASA Astrophysics Data System (ADS)

Miah, M.; Rodgers, A. J.; McCallen, D.; Petersson, N. A.; Pitarka, A.

2017-12-01

We are running high-performance computing (HPC) simulations of ground motions for large (magnitude, M=6.5-7.0) earthquakes in the near-fault region (< 50 km) to 5 Hz and higher. Ground motions are then used as forcing functions for canonical steel moment frame buildings throughout the near-fault domain. For ground motions, we are using SW4, a fourth order summation-by-parts finite difference time-domain code running on 10,000-100,000's of cores. Earthquake ruptures are generated using the Graves and Pitarka (2017) method. We validated ground motion intensity measurements against Ground Motion Prediction Equations. We considered two events (M=6.5 and 7.0) for vertical strike-slip ruptures with three-dimensional (3D) basin structures, including stochastic heterogeneity. We have also considered M7.0 scenarios for a Hayward Fault rupture scenario which effects the San Francisco Bay Area and northern California using both 1D and 3D earth structure. Dynamic, inelastic response of canonical buildings is computed with the NEVADA, a nonlinear, finite-deformation finite element code. Canonical buildings include 3-, 9-, 20- and 40-story steel moment frame buildings. Damage potential is tracked by the peak inter-story drift (PID) ratio, which measures the maximum displacement between adjacent floors of the building and is strongly correlated with damage. PID ratios greater 1.0 generally indicate non-linear response and permanent deformation of the structure. We also track roof displacement to identify permanent deformation. PID (damage) for a given earthquake scenario (M, slip distribution, hypocenter) is spatially mapped throughout the SW4 domain with 1-2 km resolution. Results show that in the near fault region building damage is correlated with peak ground velocity (PGV), while farther away (> 20 km) it is better correlated with peak ground acceleration (PGA). We also show how simulated ground motions have peaks in the response spectra that shift to longer periods for larger magnitude events and for locations of forward directivity, as has been reported by Sommerville (2003). These advanced numerical simulation capabilities provide a detailed look at the regional distribution of ground motions and allow us to quantify how ground motion hazard translate to risk for specific structures on a regional scale.

Adapting Surface Ground Motion Relations to Underground conditions: A case study for the Sudbury Neutrino Observatory in Sudbury, Ontario, Canada

NASA Astrophysics Data System (ADS)

Babaie Mahani, A.; Eaton, D. W.

2013-12-01

Ground Motion Prediction Equations (GMPEs) are widely used in Probabilistic Seismic Hazard Assessment (PSHA) to estimate ground-motion amplitudes at Earth's surface as a function of magnitude and distance. Certain applications, such as hazard assessment for caprock integrity in the case of underground storage of CO2, waste disposal sites, and underground pipelines, require subsurface estimates of ground motion; at present, such estimates depend upon theoretical modeling and simulations. The objective of this study is to derive correction factors for GMPEs to enable estimation of amplitudes in the subsurface. We use a semi-analytic approach along with finite-difference simulations of ground-motion amplitudes for surface and underground motions. Spectral ratios of underground to surface motions are used to calculate the correction factors. Two predictive methods are used. The first is a semi-analytic approach based on a quarter-wavelength method that is widely used for earthquake site-response investigations; the second is a numerical approach based on elastic finite-difference simulations of wave propagation. Both methods are evaluated using recordings of regional earthquakes by broadband seismometers installed at the surface and at depths of 1400 m and 2100 m in the Sudbury Neutrino Observatory, Canada. Overall, both methods provide a reasonable fit to the peaks and troughs observed in the ratios of real data. The finite-difference method, however, has the capability to simulate ground motion ratios more accurately than the semi-analytic approach.

Strong Ground Motion Generation during the 2011 Tohoku-Oki Earthquake

NASA Astrophysics Data System (ADS)

Asano, K.; Iwata, T.

2011-12-01

Strong ground motions during the 2011 Tohoku-Oki earthquake (Mw9.0) were densely observed by the strong motion observation networks all over Japan. Seeing the acceleration and velocity waveforms observed at strong stations in northeast Japan along the source region, those ground motions are characterized by plural wave packets with duration of about twenty seconds. Particularly, two wave packets separated by about fifty seconds could be found on the records in the northern part of the damaged area, whereas only one significant wave packets could be recognized on the records in the southern part of the damaged area. The record section shows four isolated wave packets propagating from different locations to north and south, and it gives us a hint of the strong motion generation process on the source fault which is related to the heterogeneous rupture process in the scale of tens of kilometers. In order to solve it, we assume that each isolated wave packet is contributed by the corresponding strong motion generation area (SMGA). It is a source patch whose slip velocity is larger than off the area (Miyake et al., 2003). That is, the source model of the 2011 Tohoku-Oki earthquake consists of four SMGAs. The SMGA source model has succeeded in reproducing broadband strong ground motions for past subduction-zone events (e.g., Suzuki and Iwata, 2007). The target frequency range is set to be 0.1-10 Hz in this study as this range is significantly related to seismic damage generation to general man-made structures. First, we identified the rupture starting points of each SMGA by picking up the onset of individual packets. The source fault plane is set following the GCMT solution. The first two SMGAs were located approximately 70 km and 30 km west of the hypocenter. The third and forth SMGAs were located approximately 160 km and 230 km southwest of the hypocenter. Then, the model parameters (size, rise time, stress drop, rupture velocity, rupture propagation pattern) of these four SMGAs were determined by waveform modeling using the empirical Green's function method (Irikura, 1986). The first and second SMGAs are located close to each other, and they are partially overlapped though the difference in the rupture time between them is more than 40 s. Those two SMGA appear to be included in the source region of the past repeating Miyagi-Oki subduction-zone event in 1936. The third and fourth SMGAs appear to be located in the source region of the past Fukushima-Oki events in 1938. Each of Those regions has been expected to cause next major earthquakes in the long-term evaluation. The obtained source model explains the acceleration, velocity, and displacement time histories in the target frequency range at most stations well. All of four SMGAs exist apparently outside of the large slip area along the trench east of the hypocenter, which was estimated by the seismic, geodetic, and tsunami inversion analyses, and this large slip zone near the trench does not contribute to strong motion much. At this point, we can conclude that the 2011 Tohoku-Oki earthquake has a possibility to be a complex event rupturing multiple preexisting asperities in terms of strong ground motion generation. It should be helpful to validate and improve the applicability of the strong motion prediction recipe for great subduction-zone earthquakes.

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

Kennedy, R.P.; Kincaid, R.H.; Short, S.A.

This report presents the results of part of a two-task study on the engineering characterization of earthquake ground motion for nuclear power plant design. Task I of the study, which is presented in NUREG/CR-3805, Vol. 1, developed a basis for selecting design response spectra taking into account the characteristics of free-field ground motion found to be significant in causing structural damage. Task II incorporates additional considerations of effects of spatial variations of ground motions and soil-structure interaction on foundation motions and structural response. The results of Task II are presented in four parts: (1) effects of ground motion characteristics onmore » structural response of a typical PWR reactor building with localized nonlinearities and soil-structure interaction effects; (2) empirical data on spatial variations of earthquake ground motion; (3) soil-structure interaction effects on structural response; and (4) summary of conclusions and recommendations based on Tasks I and II studies. This report presents the results of the first part of Task II. The results of the other parts will be presented in NUREG/CR-3805, Vols. 3 to 5.« less

Seismic fragility curves of bridge piers accounting for ground motions in Korea

NASA Astrophysics Data System (ADS)

Nguyen, Duy-Duan; Lee, Tae-Hyung

2018-04-01

Korea is located in a slight-to-moderate seismic zone. Nevertheless, several studies pointed that the peak earthquake magnitude in the region can be reached to approximately 6.5. Accordingly, a seismic vulnerability evaluation of the existing structures accounting for ground motions in Korea is momentous. The purpose of this paper is to develop seismic fragility curves for bridge piers of a steel box girder bridge equipped with and without base isolators based on a set of ground motions recorded in Korea. A finite element simulation platform, OpenSees, is utilized to perform nonlinear time history analyses of the bridges. A series of damage states is defined based on a damage index which is expressed in terms of the column displacement ductility ratio. The fragility curves based on Korean motions were thereafter compared with the fragility curves generated using worldwide earthquakes to assess the effect of the two ground motion groups on the seismic fragility curves of the bridge piers. The results reveal that both non- and base-isolated bridge piers are less vulnerable during the Korean ground motions than that under worldwide earthquakes.

Broadband Ground Motion Simulation Recipe for Scenario Hazard Assessment in Japan

NASA Astrophysics Data System (ADS)

Koketsu, K.; Fujiwara, H.; Irikura, K.

2014-12-01

The National Seismic Hazard Maps for Japan, which consist of probabilistic seismic hazard maps (PSHMs) and scenario earthquake shaking maps (SESMs), have been published every year since 2005 by the Earthquake Research Committee (ERC) in the Headquarter for Earthquake Research Promotion, which was established in the Japanese government after the 1995 Kobe earthquake. The publication was interrupted due to problems in the PSHMs revealed by the 2011 Tohoku earthquake, and the Subcommittee for Evaluations of Strong Ground Motions ('Subcommittee') has been examining the problems for two and a half years (ERC, 2013; Fujiwara, 2014). However, the SESMs and the broadband ground motion simulation recipe used in them are still valid at least for crustal earthquakes. Here, we outline this recipe and show the results of validation tests for it.Irikura and Miyake (2001) and Irikura (2004) developed a recipe for simulating strong ground motions from future crustal earthquakes based on a characterization of their source models (Irikura recipe). The result of the characterization is called a characterized source model, where a rectangular fault includes a few rectangular asperities. Each asperity and the background area surrounding the asperities have their own uniform stress drops. The Irikura recipe defines the parameters of the fault and asperities, and how to simulate broadband ground motions from the characterized source model. The recipe for the SESMs was constructed following the Irikura recipe (ERC, 2005). The National Research Institute for Earth Science and Disaster Prevention (NIED) then made simulation codes along this recipe to generate SESMs (Fujiwara et al., 2006; Morikawa et al., 2011). The Subcommittee in 2002 validated a preliminary version of the SESM recipe by comparing simulated and observed ground motions for the 2000 Tottori earthquake. In 2007 and 2008, the Subcommittee carried out detailed validations of the current version of the SESM recipe and the NIED codes using ground motions from the 2005 Fukuoka earthquake. Irikura and Miyake (2011) summarized the latter validations, concluding that the ground motions were successfully simulated as shown in the figure. This indicates that the recipe has enough potential to generate broadband ground motions for scenario hazard assessment in Japan.

Hazard assessment of long-period ground motions for the Nankai Trough earthquakes

NASA Astrophysics Data System (ADS)

Maeda, T.; Morikawa, N.; Aoi, S.; Fujiwara, H.

2013-12-01

We evaluate a seismic hazard for long-period ground motions associated with the Nankai Trough earthquakes (M8~9) in southwest Japan. Large interplate earthquakes occurring around the Nankai Trough have caused serious damages due to strong ground motions and tsunami; most recent events were in 1944 and 1946. Such large interplate earthquake potentially causes damages to high-rise and large-scale structures due to long-period ground motions (e.g., 1985 Michoacan earthquake in Mexico, 2003 Tokachi-oki earthquake in Japan). The long-period ground motions are amplified particularly on basins. Because major cities along the Nankai Trough have developed on alluvial plains, it is therefore important to evaluate long-period ground motions as well as strong motions and tsunami for the anticipated Nankai Trough earthquakes. The long-period ground motions are evaluated by the finite difference method (FDM) using 'characterized source models' and the 3-D underground structure model. The 'characterized source model' refers to a source model including the source parameters necessary for reproducing the strong ground motions. The parameters are determined based on a 'recipe' for predicting strong ground motion (Earthquake Research Committee (ERC), 2009). We construct various source models (~100 scenarios) giving the various case of source parameters such as source region, asperity configuration, and hypocenter location. Each source region is determined by 'the long-term evaluation of earthquakes in the Nankai Trough' published by ERC. The asperity configuration and hypocenter location control the rupture directivity effects. These parameters are important because our preliminary simulations are strongly affected by the rupture directivity. We apply the system called GMS (Ground Motion Simulator) for simulating the seismic wave propagation based on 3-D FDM scheme using discontinuous grids (Aoi and Fujiwara, 1999) to our study. The grid spacing for the shallow region is 200 m and 100 m in horizontal and vertical, respectively. The grid spacing for the deep region is three times coarser. The total number of grid points is about three billion. The 3-D underground structure model used in the FD simulation is the Japan integrated velocity structure model (ERC, 2012). Our simulation is valid for period more than two seconds due to the lowest S-wave velocity and grid spacing. However, because the characterized source model may not sufficiently support short period components, we should be interpreted the reliable period of this simulation with caution. Therefore, we consider the period more than five seconds instead of two seconds for further analysis. We evaluate the long-period ground motions using the velocity response spectra for the period range between five and 20 second. The preliminary simulation shows a large variation of response spectra at a site. This large variation implies that the ground motion is very sensitive to different scenarios. And it requires studying the large variation to understand the seismic hazard. Our further study will obtain the hazard curves for the Nankai Trough earthquake (M 8~9) by applying the probabilistic seismic hazard analysis to the simulation results.

Reanimating patients: cardio-respiratory CT and MR motion phantoms based on clinical CT patient data

NASA Astrophysics Data System (ADS)

Mayer, Johannes; Sauppe, Sebastian; Rank, Christopher M.; Sawall, Stefan; Kachelrieß, Marc

2017-03-01

Until today several algorithms have been developed that reduce or avoid artifacts caused by cardiac and respiratory motion in computed tomography (CT). The motion information is converted into so-called motion vector fields (MVFs) and used for motion compensation (MoCo) during the image reconstruction. To analyze these algorithms quantitatively there is the need for ground truth patient data displaying realistic motion. We developed a method to generate a digital ground truth displaying realistic cardiac and respiratory motion that can be used as a tool to assess MoCo algorithms. By the use of available MoCo methods we measured the motion in CT scans with high spatial and temporal resolution and transferred the motion information onto patient data with different anatomy or imaging modality, thereby reanimating the patient virtually. In addition to these images the ground truth motion information in the form of MVFs is available and can be used to benchmark the MVF estimation of MoCo algorithms. We here applied the method to generate 20 CT volumes displaying detailed cardiac motion that can be used for cone-beam CT (CBCT) simulations and a set of 8 MR volumes displaying respiratory motion. Our method is able to reanimate patient data virtually. In combination with the MVFs it serves as a digital ground truth and provides an improved framework to assess MoCo algorithms.

Strong ground motion from the November 12, 2017, M 7.3 Kermanshah earthquake in western Iran

NASA Astrophysics Data System (ADS)

Babaie Mahani, Alireza; Kazemian, Javad

2018-05-01

In this paper, we analyzed the strong ground motion from the November 12, 2017, Kermanshah earthquake in western Iran with moment magnitude (M) of 7.3. Nonlinear and linear amplification of ground motion amplitudes were observed at stations with soft soil condition at hypocentral distances below and above 100 km, respectively. Observation of large ground motion amplitudes dominated with long-period pulses on the strike-normal component of the velocity time series suggests a right-lateral component of movement and propagation of rupture towards southeast. Comparison of the horizontal peak ground acceleration (PGA) from the M 7.3 earthquake with global PGA values showed a similar decay in ground motion amplitudes, although it seems that PGA from the M 7.3 Kermanshah earthquake is higher than global values for NEHRP site class B. We also found that the bracketed duration (D b) was higher in the velocity domain than in the acceleration domain for the same modified Mercalli intensity (MMI) threshold. For example, D b reached 30 s at the maximum PGA while it was 50 s at the maximum peak ground velocity above the threshold of MMI = 5. Although the standard design spectrum from Iranian Code of Practice for Seismic Resistant Design of Buildings (standard No. 2800) seems to include appropriate values for the design of structures with fundamental period of 1 s and higher, it is underestimated for near-field ground motions at lower periods.

High Frequency Near-Field Ground Motion Excited by Strike-Slip Step Overs

NASA Astrophysics Data System (ADS)

Hu, Feng; Wen, Jian; Chen, Xiaofei

2018-03-01

We performed dynamic rupture simulations on step overs with 1-2 km step widths and present their corresponding horizontal peak ground velocity distributions in the near field within different frequency ranges. The rupture speeds on fault segments are determinant in controlling the near-field ground motion. A Mach wave impact area at the free surface, which can be inferred from the distribution of the ratio of the maximum fault-strike particle velocity to the maximum fault-normal particle velocity, is generated in the near field with sustained supershear ruptures on fault segments, and the Mach wave impact area cannot be detected with unsustained supershear ruptures alone. Sub-Rayleigh ruptures produce stronger ground motions beyond the end of fault segments. The existence of a low-velocity layer close to the free surface generates large amounts of high-frequency seismic radiation at step over discontinuities. For near-vertical step overs, normal stress perturbations on the primary fault caused by dipping structures affect the rupture speed transition, which further determines the distribution of the near-field ground motion. The presence of an extensional linking fault enhances the near-field ground motion in the extensional regime. This work helps us understand the characteristics of high-frequency seismic radiation in the vicinities of step overs and provides useful insights for interpreting the rupture speed distributions derived from the characteristics of near-field ground motion.

Comparison of ground motion from tremors and explosions in deep gold mines

USGS Publications Warehouse

McGarr, A.; Bicknell, J.; Churcher, J.; Spottiswoode, S.

1990-01-01

Seismic body waves, from tamped chemical explosions, two with yields of 50 and one of 150 kg, were compared with corresponding data from three mining-induced tremors with a view to testing methods of discriminating between the two types of events. It is concluded that for events of fixed low-frequency spectral asymptotes, the explosions typically have higher corner frequencies than tremors or earthquakes, although counterexamples certainly exist. Interestingly, the 150-kg explosion was identified as such on the basis of P and S wave polarities that are incompatible with the normally expected double-couple source model; instead these initial motions are consistent with an explosion in conjunction with normal faulting. The body wave spectra of this explosion and those of a nearby tremor, however, were indistinguishable. -from Authors

Comparison Virtual Landing Gear Drop Test for Commuter Aircraft Utilize MSC ADAMS And Solidworks Motion Analysis

NASA Astrophysics Data System (ADS)

Hidayat, Dony; Istiyanto, Jos; Agus Sumarsono, Danardono

2018-04-01

Loads at main landing gear while touchdown impact is function of aircraft weight and ground reaction load factor. In regulation states ground reaction load factor at Vsink = 3.05 m/s is below 3. Contact/impact force from simulation using MSC ADAMS is 94680 N, while using Solidworks Motion Analysis is 97691 N. The difference between MSC ADAMS and Solidworks Motion Analysis is 3.08%. The ground reaction load factor in MSC ADAMS is 2.78 while in Solidworks Motion Analysis is 2.87.

An atlas of ShakeMaps for selected global earthquakes

USGS Publications Warehouse

Allen, Trevor I.; Wald, David J.; Hotovec, Alicia J.; Lin, Kuo-Wan; Earle, Paul S.; Marano, Kristin D.

2008-01-01

An atlas of maps of peak ground motions and intensity 'ShakeMaps' has been developed for almost 5,000 recent and historical global earthquakes. These maps are produced using established ShakeMap methodology (Wald and others, 1999c; Wald and others, 2005) and constraints from macroseismic intensity data, instrumental ground motions, regional topographically-based site amplifications, and published earthquake-rupture models. Applying the ShakeMap methodology allows a consistent approach to combine point observations with ground-motion predictions to produce descriptions of peak ground motions and intensity for each event. We also calculate an estimated ground-motion uncertainty grid for each earthquake. The Atlas of ShakeMaps provides a consistent and quantitative description of the distribution and intensity of shaking for recent global earthquakes (1973-2007) as well as selected historic events. As such, the Atlas was developed specifically for calibrating global earthquake loss estimation methodologies to be used in the U.S. Geological Survey Prompt Assessment of Global Earthquakes for Response (PAGER) Project. PAGER will employ these loss models to rapidly estimate the impact of global earthquakes as part of the USGS National Earthquake Information Center's earthquake-response protocol. The development of the Atlas of ShakeMaps has also led to several key improvements to the Global ShakeMap system. The key upgrades include: addition of uncertainties in the ground motion mapping, introduction of modern ground-motion prediction equations, improved estimates of global seismic-site conditions (VS30), and improved definition of stable continental region polygons. Finally, we have merged all of the ShakeMaps in the Atlas to provide a global perspective of earthquake ground shaking for the past 35 years, allowing comparison with probabilistic hazard maps. The online Atlas and supporting databases can be found at http://earthquake.usgs.gov/eqcenter/shakemap/atlas.php/.

Physical limits on ground motion at Yucca Mountain

USGS Publications Warehouse

Andrews, D.J.; Hanks, T.C.; Whitney, J.W.

2007-01-01

Physical limits on possible maximum ground motion at Yucca Mountain, Nevada, the designated site of a high-level radioactive waste repository, are set by the shear stress available in the seismogenic depth of the crust and by limits on stress change that can propagate through the medium. We find in dynamic deterministic 2D calculations that maximum possible horizontal peak ground velocity (PGV) at the underground repository site is 3.6 m/sec, which is smaller than the mean PGV predicted by the probabilistic seismic hazard analysis (PSHA) at annual exceedance probabilities less than 10-6 per year. The physical limit on vertical PGV, 5.7 m/sec, arises from supershear rupture and is larger than that from the PSHA down to 10-8 per year. In addition to these physical limits, we also calculate the maximum ground motion subject to the constraint of known fault slip at the surface, as inferred from paleoseismic studies. Using a published probabilistic fault displacement hazard curve, these calculations provide a probabilistic hazard curve for horizontal PGV that is lower than that from the PSHA. In all cases the maximum ground motion at the repository site is found by maximizing constructive interference of signals from the rupture front, for physically realizable rupture velocity, from all parts of the fault. Vertical PGV is maximized for ruptures propagating near the P-wave speed, and horizontal PGV is maximized for ruptures propagating near the Rayleigh-wave speed. Yielding in shear with a Mohr-Coulomb yield condition reduces ground motion only a modest amount in events with supershear rupture velocity, because ground motion consists primarily of P waves in that case. The possibility of compaction of the porous unsaturated tuffs at the higher ground-motion levels is another attenuating mechanism that needs to be investigated.

Modal-pushover-based ground-motion scaling procedure

USGS Publications Warehouse

Kalkan, Erol; Chopra, Anil K.

2011-01-01

Earthquake engineering is increasingly using nonlinear response history analysis (RHA) to demonstrate the performance of structures. This rigorous method of analysis requires selection and scaling of ground motions appropriate to design hazard levels. This paper presents a modal-pushover-based scaling (MPS) procedure to scale ground motions for use in a nonlinear RHA of buildings. In the MPS method, the ground motions are scaled to match to a specified tolerance, a target value of the inelastic deformation of the first-mode inelastic single-degree-of-freedom (SDF) system whose properties are determined by the first-mode pushover analysis. Appropriate for first-mode dominated structures, this approach is extended for structures with significant contributions of higher modes by considering elastic deformation of second-mode SDF systems in selecting a subset of the scaled ground motions. Based on results presented for three actual buildings-4, 6, and 13-story-the accuracy and efficiency of the MPS procedure are established and its superiority over the ASCE/SEI 7-05 scaling procedure is demonstrated.

Estimation of Source and Attenuation Parameters from Ground Motion Observations for Induced Seismicity in Alberta

NASA Astrophysics Data System (ADS)

Novakovic, M.; Atkinson, G. M.

2015-12-01

We use a generalized inversion to solve for site response, regional source and attenuation parameters, in order to define a region-specific ground-motion prediction equation (GMPE) from ground motion observations in Alberta, following the method of Atkinson et al. (2015 BSSA). The database is compiled from over 200 small to moderate seismic events (M 1 to 4.2) recorded at ~50 regional stations (distances from 30 to 500 km), over the last few years; almost all of the events have been identified as being induced by oil and gas activity. We remove magnitude scaling and geometric spreading functions from observed ground motions and invert for stress parameter, regional attenuation and site amplification. Resolving these parameters allows for the derivation of a regionally-calibrated GMPE that can be used to accurately predict amplitudes across the region in real time, which is useful for ground-motion-based alerting systems and traffic light protocols. The derived GMPE has further applications for the evaluation of hazards from induced seismicity.

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

Pasyanos, Michael E.

Recently developed attenuation models are incorporated into standard one-dimensional (1-D) ground motion prediction equations (GMPEs), effectively making them two-dimensional (2-D) and eliminating the need to create different GMPEs for an increasing number of sub-regions. The model is tested against a data set of over 10,000 recordings from 81 earthquakes in North America. The use of attenuation models in GMPEs improves our ability to fit observed ground motions and should be incorporated into future national hazard maps. The improvement is most significant at higher frequencies and longer distances which have a greater number of wave cycles. This has implications for themore » rare high-magnitude earthquakes, which produce potentially damaging ground motions over wide areas, and drive the seismic hazards. Furthermore, the attenuation models can be created using weak ground motions, they could be developed for regions of low seismicity where empirical recordings of ground motions are uncommon and do not span the full range of magnitudes and distances.« less

Free Swimming in Ground Effect

NASA Astrophysics Data System (ADS)

Cochran-Carney, Jackson; Wagenhoffer, Nathan; Zeyghami, Samane; Moored, Keith

2017-11-01

A free-swimming potential flow analysis of unsteady ground effect is conducted for two-dimensional airfoils via a method of images. The foils undergo a pure pitching motion about their leading edge, and the positions of the body in the streamwise and cross-stream directions are determined by the equations of motion of the body. It is shown that the unconstrained swimmer is attracted to a time-averaged position that is mediated by the flow interaction with the ground. The robustness of this fluid-mediated equilibrium position is probed by varying the non-dimensional mass, initial conditions and kinematic parameters of motion. Comparisons to the foil's fixed-motion counterpart are also made to pinpoint the effect that free swimming near the ground has on wake structures and the fluid-mediated forces over time. Optimal swimming regimes for near-boundary swimming are determined by examining asymmetric motions.

A simple model for strong ground motions and response spectra

USGS Publications Warehouse

Safak, Erdal; Mueller, Charles; Boatwright, John

1988-01-01

A simple model for the description of strong ground motions is introduced. The model shows that response spectra can be estimated by using only four parameters of the ground motion, the RMS acceleration, effective duration and two corner frequencies that characterize the effective frequency band of the motion. The model is windowed band-limited white noise, and is developed by studying the properties of two functions, cumulative squared acceleration in the time domain, and cumulative squared amplitude spectrum in the frequency domain. Applying the methods of random vibration theory, the model leads to a simple analytical expression for the response spectra. The accuracy of the model is checked by using the ground motion recordings from the aftershock sequences of two different earthquakes and simulated accelerograms. The results show that the model gives a satisfactory estimate of the response spectra.

Combined GPS and seismic monitoring of a 12-story structure in a region of induced seismicity in Oklahoma

NASA Astrophysics Data System (ADS)

Haase, J. S.; Soliman, M.; Kim, H.; Jaiswal, P.; Saunders, J. K.; Vernon, F.; Zhang, W.

2017-12-01

This work focuses on quantifying ground motions and their effects in Oklahoma near the location of the 2016 Mw 5.8 Pawnee earthquake, where seismicity has been increasing due to wastewater injection related to oil and natural gas production. Much of the building inventory in Oklahoma was constructed before the increase in seismicity and before the implementation of earthquake design and detailing provisions for reinforced concrete (RC) structures. We will use combined GPS/seismic monitoring techniques to measure ground motion in the field and the response of structures to this ground motion. Several Oklahoma State University buildings experienced damage due to the Pawnee earthquake. The USGS Shake Map product estimated peak ground acceleration (PGA) ranging from 0.12g to 0.15g at campus locations. We are deploying a high-rate GPS sensor and accelerometer on the roof and another accelerometer at ground level of a 12-story RC structure and at selected field sites in order to collect ambient noise data and nearby seismicity. The longer period recording characteristics of the GPS/seismic system are particularly well adapted to monitoring these large structures in the event of a significant earthquake. Gross characteristics of the structural system are described, which consists of RC columns and RC slabs in all stories. We conducted a preliminary structural analysis including modal analysis and response spectrum analysis based on a finite element (FE) simulation, which indicated that the period associated with the first X-axis bending, first torsional, and first Y-axis bending modes are 2.2 s, 2.1 s, and 1.8 s, respectively. Next, a preliminary analysis was conducted to estimate the range of expected deformation at the roof level for various earthquake excitations. The earthquake analysis shows a maximum roof displacement of 5 and 7 cm in the horizontal directions resulting from earthquake loads with PGA of 0.2g, well above the noise level of the combined GPS/seismic displacements. Another earthquake comparable to the Pawnee earthquake should be well recorded by the system. Recordings of ambient vibration data collected to date describing noise characteristics and measurement error levels will be presented. Any recordings of seismic motions will be discussed, should a significant event occur.

Modeling the Interaction between Fluid Pressure and Faulting in an Earthquake Swarm at Long Valley Caldera

NASA Astrophysics Data System (ADS)

Haase, J. S.; Soliman, M.; Kim, H.; Jaiswal, P.; Saunders, J. K.; Vernon, F.; Zhang, W.

2016-12-01

This work focuses on quantifying ground motions and their effects in Oklahoma near the location of the 2016 Mw 5.8 Pawnee earthquake, where seismicity has been increasing due to wastewater injection related to oil and natural gas production. Much of the building inventory in Oklahoma was constructed before the increase in seismicity and before the implementation of earthquake design and detailing provisions for reinforced concrete (RC) structures. We will use combined GPS/seismic monitoring techniques to measure ground motion in the field and the response of structures to this ground motion. Several Oklahoma State University buildings experienced damage due to the Pawnee earthquake. The USGS Shake Map product estimated peak ground acceleration (PGA) ranging from 0.12g to 0.15g at campus locations. We are deploying a high-rate GPS sensor and accelerometer on the roof and another accelerometer at ground level of a 12-story RC structure and at selected field sites in order to collect ambient noise data and nearby seismicity. The longer period recording characteristics of the GPS/seismic system are particularly well adapted to monitoring these large structures in the event of a significant earthquake. Gross characteristics of the structural system are described, which consists of RC columns and RC slabs in all stories. We conducted a preliminary structural analysis including modal analysis and response spectrum analysis based on a finite element (FE) simulation, which indicated that the period associated with the first X-axis bending, first torsional, and first Y-axis bending modes are 2.2 s, 2.1 s, and 1.8 s, respectively. Next, a preliminary analysis was conducted to estimate the range of expected deformation at the roof level for various earthquake excitations. The earthquake analysis shows a maximum roof displacement of 5 and 7 cm in the horizontal directions resulting from earthquake loads with PGA of 0.2g, well above the noise level of the combined GPS/seismic displacements. Another earthquake comparable to the Pawnee earthquake should be well recorded by the system. Recordings of ambient vibration data collected to date describing noise characteristics and measurement error levels will be presented. Any recordings of seismic motions will be discussed, should a significant event occur.

Characteristics of strong ground motion generation areas by fully dynamic earthquake cycles

NASA Astrophysics Data System (ADS)

Galvez, P.; Somerville, P.; Ampuero, J. P.; Petukhin, A.; Yindi, L.

2016-12-01

During recent subduction zone earthquakes (2010 Mw 8.8 Maule and 2011 Mw 9.0 Tohoku), high frequency ground motion radiation has been detected in deep regions of seismogenic zones. By semblance analysis of wave packets, Kurahashi & Irikura (2013) found strong ground motion generation areas (SMGAs) located in the down dip region of the 2011 Tohoku rupture. To reproduce the rupture sequence of SMGA's and replicate their rupture time and ground motions, we extended previous work on dynamic rupture simulations with slip reactivation (Galvez et al, 2016). We adjusted stresses on the most southern SMGAs of Kurahashi & Irikura (2013) model to reproduce the observed peak ground velocity recorded at seismic stations along Japan for periods up to 5 seconds. To generate higher frequency ground motions we input the rupture time, final slip and slip velocity of the dynamic model into the stochastic ground motion generator of Graves & Pitarka (2010). Our results are in agreement with the ground motions recorded at the KiK-net and K-NET stations.While we reproduced the recorded ground motions of the 2011 Tohoku event, it is unknown whether the characteristics and location of SMGA's will persist in future large earthquakes in this region. Although the SMGA's have large peak slip velocities, the areas of largest final slip are located elsewhere. To elucidate whether this anti-correlation persists in time, we conducted earthquake cycle simulations and analysed the spatial correlation of peak slip velocities, stress drops and final slip of main events. We also investigated whether or not the SMGA's migrate to other regions of the seismic zone.To perform this study, we coupled the quasi-dynamic boundary element solver QDYN (Luo & Ampuero, 2015) and the dynamic spectral element solver SPECFEM3D (Galvez et al., 2014; 2016). The workflow alternates between inter-seismic periods solved with QDYN and coseismic periods solved with SPECFEM3D, with automated switch based on slip rate thersholds (Kaneko et al., 2011). We parallelized QDYN with MPI to enable the simulation of fully dynamic earthquake cycles of Mw 8-9 earthquakes in faults that also produce Mw 7 earthquakes.This study was based on the 2015 research project `Improvement for uncertainty of strong ground motion prediction' by the Nuclear Regulation Authority (NRA), Japan.

A comparison of observed and predicted ground motions from the 2015 MW7.8 Gorkha, Nepal, earthquake

USGS Publications Warehouse

Hough, Susan E.; Martin, Stacey S.; Gahalaut, V.; Joshi, A.; Landes, M.; Bossu, R.

2016-01-01

We use 21 strong motion recordings from Nepal and India for the 25 April 2015 moment magnitude (MW) 7.8 Gorkha, Nepal, earthquake together with the extensive macroseismic intensity data set presented by Martin et al. (Seism Res Lett 87:957–962, 2015) to analyse the distribution of ground motions at near-field and regional distances. We show that the data are consistent with the instrumental peak ground acceleration (PGA) versus macroseismic intensity relationship developed by Worden et al. (Bull Seism Soc Am 102:204–221, 2012), and use this relationship to estimate peak ground acceleration from intensities (PGAEMS). For nearest-fault distances (RRUP < 200 km), PGAEMS is consistent with the Atkinson and Boore (Bull Seism Soc Am 93:1703–1729, 2003) subduction zone ground motion prediction equation (GMPE). At greater distances (RRUP > 200 km), instrumental PGA values are consistent with this GMPE, while PGAEMS is systematically higher. We suggest the latter reflects a duration effect whereby effects of weak shaking are enhanced by long-duration and/or long-period ground motions from a large event at regional distances. We use PGAEMS values within 200 km to investigate the variability of high-frequency ground motions using the Atkinson and Boore (Bull Seism Soc Am 93:1703–1729, 2003) GMPE as a baseline. Across the near-field region, PGAEMS is higher by a factor of 2.0–2.5 towards the northern, down-dip edge of the rupture compared to the near-field region nearer to the southern, up-dip edge of the rupture. Inferred deamplification in the deepest part of the Kathmandu valley supports the conclusion that former lake-bed sediments experienced a pervasive nonlinear response during the mainshock (Dixit et al. in Seismol Res Lett 86(6):1533–1539, 2015; Rajaure et al. in Tectonophysics, 2016. Ground motions were significantly amplified in the southern Gangetic basin, but were relatively low in the northern basin. The overall distribution of ground motions and damage during the Gorkha earthquake thus reflects a combination of complex source, path, and site effects. We also present a macroseismic intensity data set and analysis of ground motions for the MW7.3 Dolakha aftershock on 12 May 2015, which we compare to the Gorkha mainshock and conclude was likely a high stress-drop event.

Data Files for Ground-Motion Simulations of the 1906 San Francisco Earthquake and Scenario Earthquakes on the Northern San Andreas Fault

USGS Publications Warehouse

Aagaard, Brad T.; Barall, Michael; Brocher, Thomas M.; Dolenc, David; Dreger, Douglas; Graves, Robert W.; Harmsen, Stephen; Hartzell, Stephen; Larsen, Shawn; McCandless, Kathleen; Nilsson, Stefan; Petersson, N. Anders; Rodgers, Arthur; Sjogreen, Bjorn; Zoback, Mary Lou

2009-01-01

This data set contains results from ground-motion simulations of the 1906 San Francisco earthquake, seven hypothetical earthquakes on the northern San Andreas Fault, and the 1989 Loma Prieta earthquake. The bulk of the data consists of synthetic velocity time-histories. Peak ground velocity on a 1/60th degree grid and geodetic displacements from the simulations are also included. Details of the ground-motion simulations and analysis of the results are discussed in Aagaard and others (2008a,b).

3D ground‐motion simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone: Variability of long‐period (T≥1  s) ground motions and sensitivity to kinematic rupture parameters

USGS Publications Warehouse

Moschetti, Morgan P.; Hartzell, Stephen; Ramirez-Guzman, Leonardo; Frankel, Arthur; Angster, Stephen J.; Stephenson, William J.

2017-01-01

We examine the variability of long‐period (T≥1  s) earthquake ground motions from 3D simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone, Utah, from a set of 96 rupture models with varying slip distributions, rupture speeds, slip velocities, and hypocenter locations. Earthquake ruptures were prescribed on a 3D fault representation that satisfies geologic constraints and maintained distinct strands for the Warm Springs and for the East Bench and Cottonwood faults. Response spectral accelerations (SA; 1.5–10 s; 5% damping) were measured, and average distance scaling was well fit by a simple functional form that depends on the near‐source intensity level SA0(T) and a corner distance Rc:SA(R,T)=SA0(T)(1+(R/Rc))−1. Period‐dependent hanging‐wall effects manifested and increased the ground motions by factors of about 2–3, though the effects appeared partially attributable to differences in shallow site response for sites on the hanging wall and footwall of the fault. Comparisons with modern ground‐motion prediction equations (GMPEs) found that the simulated ground motions were generally consistent, except within deep sedimentary basins, where simulated ground motions were greatly underpredicted. Ground‐motion variability exhibited strong lateral variations and, at some sites, exceeded the ground‐motion variability indicated by GMPEs. The effects on the ground motions of changing the values of the five kinematic rupture parameters can largely be explained by three predominant factors: distance to high‐slip subevents, dynamic stress drop, and changes in the contributions from directivity. These results emphasize the need for further characterization of the underlying distributions and covariances of the kinematic rupture parameters used in 3D ground‐motion simulations employed in probabilistic seismic‐hazard analyses.

Regionally Adaptable Ground Motion Prediction Equation (GMPE) from Empirical Models of Fourier and Duration of Ground Motion

NASA Astrophysics Data System (ADS)

Bora, Sanjay; Scherbaum, Frank; Kuehn, Nicolas; Stafford, Peter; Edwards, Benjamin

2016-04-01

The current practice of deriving empirical ground motion prediction equations (GMPEs) involves using ground motions recorded at multiple sites. However, in applications like site-specific (e.g., critical facility) hazard ground motions obtained from the GMPEs are need to be adjusted/corrected to a particular site/site-condition under investigation. This study presents a complete framework for developing a response spectral GMPE, within which the issue of adjustment of ground motions is addressed in a manner consistent with the linear system framework. The present approach is a two-step process in which the first step consists of deriving two separate empirical models, one for Fourier amplitude spectra (FAS) and the other for a random vibration theory (RVT) optimized duration (Drvto) of ground motion. In the second step the two models are combined within the RVT framework to obtain full response spectral amplitudes. Additionally, the framework also involves a stochastic model based extrapolation of individual Fourier spectra to extend the useable frequency limit of the empirically derived FAS model. The stochastic model parameters were determined by inverting the Fourier spectral data using an approach similar to the one as described in Edwards and Faeh (2013). Comparison of median predicted response spectra from present approach with those from other regional GMPEs indicates that the present approach can also be used as a stand-alone model. The dataset used for the presented analysis is a subset of the recently compiled database RESORCE-2012 across Europe, the Middle East and the Mediterranean region.

Ground-motion modeling of Hayward fault scenario earthquakes, part II: Simulation of long-period and broadband ground motions

USGS Publications Warehouse

Aagaard, Brad T.; Graves, Robert W.; Rodgers, Arthur; Brocher, Thomas M.; Simpson, Robert W.; Dreger, Douglas; Petersson, N. Anders; Larsen, Shawn C.; Ma, Shuo; Jachens, Robert C.

2010-01-01

We simulate long-period (T>1.0–2.0 s) and broadband (T>0.1 s) ground motions for 39 scenario earthquakes (Mw 6.7–7.2) involving the Hayward, Calaveras, and Rodgers Creek faults. For rupture on the Hayward fault, we consider the effects of creep on coseismic slip using two different approaches, both of which reduce the ground motions, compared with neglecting the influence of creep. Nevertheless, the scenario earthquakes generate strong shaking throughout the San Francisco Bay area, with about 50% of the urban area experiencing modified Mercalli intensity VII or greater for the magnitude 7.0 scenario events. Long-period simulations of the 2007 Mw 4.18 Oakland earthquake and the 2007 Mw 5.45 Alum Rock earthquake show that the U.S. Geological Survey’s Bay Area Velocity Model version 08.3.0 permits simulation of the amplitude and duration of shaking throughout the San Francisco Bay area for Hayward fault earthquakes, with the greatest accuracy in the Santa Clara Valley (San Jose area). The ground motions for the suite of scenarios exhibit a strong sensitivity to the rupture length (or magnitude), hypocenter (or rupture directivity), and slip distribution. The ground motions display a much weaker sensitivity to the rise time and rupture speed. Peak velocities, peak accelerations, and spectral accelerations from the synthetic broadband ground motions are, on average, slightly higher than the Next Generation Attenuation (NGA) ground-motion prediction equations. We attribute much of this difference to the seismic velocity structure in the San Francisco Bay area and how the NGA models account for basin amplification; the NGA relations may underpredict amplification in shallow sedimentary basins. The simulations also suggest that the Spudich and Chiou (2008) directivity corrections to the NGA relations could be improved by increasing the areal extent of rupture directivity with period.

Characteristics of ground motion at permafrost sites along the Qinghai-Tibet railway

USGS Publications Warehouse

Wang, L.; Wu, Z.; Sun, Jielun; Liu, Xiuying; Wang, Z.

2009-01-01

Based on 14 typical drilling holes distributed in the permafrost areas along the Qinghai-Tibet railway, the distribution of wave velocities of soils in the permafrost regions were determined. Using results of dynamic triaxial tests, the results of dynamic triaxiality test and time histories of ground motion acceleration in this area, characteristics of ground motion response were analyzed for these permafrost sites for time histories of ground accelerations with three exceedance probabilities (63%, 10% and 2%). The influence of ground temperature on the seismic displacement, velocity, acceleration and response spectrum on the surface of permafrost were also studied. ?? 2008 Elsevier Ltd. All rights reserved.

Near-Fault Ground Motion Velocity Pulses Input and Its Non-Stationary Characteristics from 2015 Gorkha Nepal Mw7.8 Earthquake KATNP Station

NASA Astrophysics Data System (ADS)

Chen, Bo; Wen, Zengping; Wang, Fang

2017-04-01

Using near-fault strong motions from Nepal Mw7.8 earthquake at KATNP station in the city center of Kathmandu, velocity-pulse and non-stationary characteristics of the strong motions are shown, and the reason and potential effect on earthquake damage for intense non-stationary characteristics of near fault velocity-pulse strong motions are mainly studied. The observed strong ground motions of main shock were collected from KATNP station located in 76 kilometers south-east away from epicenter along with forward direction of the rupture fault at an inter-montane basin of the Himalaya. Large velocity pulse show the period of velocity pulse reach up to 6.6s and peak ground velocity of the pulse ground motion is 120 cm/s. Compared with the median spectral acceleration value of NGA prediction equation, significant long-period amplification effect due to velocity pulse is detected at period more than 3.2s. Wavelet analysis shows that the two horizontal component of ground motion is intensely concentration of energy in a short time range of 25-38s and period range of 4-8s. The maximum wavelet-coefficient of horizontal component is 2455, which is about four time of vertical component of strong ground motion. On the perspective of this study, large velocity pulses are identified from two orthogonal components using wavelet method. Intense non-stationary characteristics amplitude and frequency content are mainly caused by site conditions and fault rupture mechanism, which will help to understand the damage evaluation and serve local seismic design.

Sampling of Stochastic Input Parameters for Rockfall Calculations and for Structural Response Calculations Under Vibratory Ground Motion

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

M. Gross

2004-09-01

The purpose of this scientific analysis is to define the sampled values of stochastic (random) input parameters for (1) rockfall calculations in the lithophysal and nonlithophysal zones under vibratory ground motions, and (2) structural response calculations for the drip shield and waste package under vibratory ground motions. This analysis supplies: (1) Sampled values of ground motion time history and synthetic fracture pattern for analysis of rockfall in emplacement drifts in nonlithophysal rock (Section 6.3 of ''Drift Degradation Analysis'', BSC 2004 [DIRS 166107]); (2) Sampled values of ground motion time history and rock mechanical properties category for analysis of rockfall inmore » emplacement drifts in lithophysal rock (Section 6.4 of ''Drift Degradation Analysis'', BSC 2004 [DIRS 166107]); (3) Sampled values of ground motion time history and metal to metal and metal to rock friction coefficient for analysis of waste package and drip shield damage to vibratory motion in ''Structural Calculations of Waste Package Exposed to Vibratory Ground Motion'' (BSC 2004 [DIRS 167083]) and in ''Structural Calculations of Drip Shield Exposed to Vibratory Ground Motion'' (BSC 2003 [DIRS 163425]). The sampled values are indices representing the number of ground motion time histories, number of fracture patterns and rock mass properties categories. These indices are translated into actual values within the respective analysis and model reports or calculations. This report identifies the uncertain parameters and documents the sampled values for these parameters. The sampled values are determined by GoldSim V6.04.007 [DIRS 151202] calculations using appropriate distribution types and parameter ranges. No software development or model development was required for these calculations. The calculation of the sampled values allows parameter uncertainty to be incorporated into the rockfall and structural response calculations that support development of the seismic scenario for the Total System Performance Assessment for the License Application (TSPA-LA). The results from this scientific analysis also address project requirements related to parameter uncertainty, as specified in the acceptance criteria in ''Yucca Mountain Review Plan, Final Report'' (NRC 2003 [DIRS 163274]). This document was prepared under the direction of ''Technical Work Plan for: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 170528]) which directed the work identified in work package ARTM05. This document was prepared under procedure AP-SIII.9Q, ''Scientific Analyses''. There are no specific known limitations to this analysis.« less

Modeling Nonlinear Site Response Uncertainty in Broadband Ground Motion Simulations for the Los Angeles Basin

NASA Astrophysics Data System (ADS)

Assimaki, D.; Li, W.; Steidl, J. M.; Schmedes, J.

2007-12-01

The assessment of strong motion site response is of great significance, both for mitigating seismic hazard and for performing detailed analyses of earthquake source characteristics. There currently exists, however, large degree of uncertainty concerning the mathematical model to be employed for the computationally efficient evaluation of local site effects, and the site investigation program necessary to evaluate the nonlinear input model parameters and ensure cost-effective predictions; and while site response observations may provide critical constraints on interpretation methods, the lack of a statistically significant number of in-situ strong motion records prohibits statistical analyses to be conducted and uncertainties to be quantified based entirely on field data. In this paper, we combine downhole observations and broadband ground motion synthetics for characteristic site conditions the Los Angeles Basin, and investigate the variability in ground motion estimation introduced by the site response assessment methodology. In particular, site-specific regional velocity and attenuation structures are initially compiled using near-surface geotechnical data collected at downhole geotechnical arrays, inverse low-strain velocity and attenuation profiles at these sites obtained by inversion of weak motion records and the crustal velocity structure at the corresponding locations obtained from the Southern California Earthquake Centre Community Velocity Model. Successively, broadband ground motions are simulated by means of a hybrid low/high-frequency finite source model with correlated random parameters for rupture scenaria of weak, medium and large magnitude events (M =3.5-7.5). Observed estimates of site response at the stations of interest are first compared to the ensemble of approximate and incremental nonlinear site response models. Parametric studies are next conducted for each fixed magnitude (fault geometry) scenario by varying the source-to-site distance and source parameters for the ensemble of site conditions. Elastic, equivalent linear and nonlinear simulations are implemented for the deterministic description of the base-model velocity and attenuation structures and nonlinear soil properties, to examine the variability in ground motion predictions as a function of ground motion amplitude and frequency content, and nonlinear site response methodology. The modeling site response uncertainty introduced in the broadband ground motion predictions is reported by means of the COV of site amplification, defined as the ratio of the predicted peak ground acceleration (PGA) and spectral acceleration (SA) at short and long periods to the corresponding intensity measure on the ground surface of a typical NEHRP BC boundary profile (Vs30=760m/s), for the ensemble of approximate and incremental nonlinear models implemented. A frequency index is developed to describe the frequency content of incident ground motion. In conjunction with the rock-outcrop acceleration level, this index is used to identify the site and ground motion conditions where incremental nonlinear analyses should be employed in lieu of approximate methodologies. Finally, the effects of modeling uncertainty in ground response analysis is evaluated in the estimation of site amplification factors, which are successively compared to recently published factors of the New Generation Attenuation Relations (NGA) and the currently employed Seismic Code Provisions (NEHRP).

Digital Imagery Compression Best Practices Guide - A Motion Imagery Standards Profile (MISP) Compliant Architecture

DTIC Science & Technology

2012-06-01

MISP) COMPLIANT ARCHITECTURE WHITE SANDS MISSILE RANGE REAGAN TEST SITE YUMA PROVING GROUND DUGWAY PROVING GROUND ABERDEEN TEST CENTER...DIGITAL MOTION IMAGERY COMPRESSION BEST PRACTICES GUIDE – A MOTION IMAGERY STANDARDS PROFILE (MISP) COMPLIANT ARCHITECTURE ...delivery, and archival purposes. These practices are based on a Motion Imagery Standards Profile (MISP) compliant architecture , which has been defined

Multi-component ground motion response spectra for coupled horizontal, vertical, angular accelerations, and tilt

USGS Publications Warehouse

Kalkan, E.; Graizer, V.

2007-01-01

Rotational and vertical components of ground motion are almost always ignored in design or in the assessment of structures despite the fact that vertical motion can be twice as much as the horizontal motion and may exceed 2g level, and rotational excitation may reach few degrees in the proximity of fault rupture. Coupling of different components of ground excitation may significantly amplify the seismic demand by introducing additional lateral forces and enhanced P-?? effects. In this paper, a governing equation of motion is postulated to compute the response of a SDOF oscillator under a multi-component excitation. The expanded equation includes secondary P-?? components associated with the combined impacts of tilt and vertical excitations in addition to the inertial forcing terms due to the angular and translational accelerations. The elastic and inelastic spectral ordinates traditionally generated considering the uniaxial input motion are compared at the end with the multi-component response spectra of coupled horizontal, vertical and tilting motions. The proposed multi-component response spectrum reflects kinematic characteristics of the ground motion that are not identifiable by the conventional spectrum itself, at least for the near-fault region where high intensity vertical shaking and rotational excitation are likely to occur.

Real-time observation of intramolecular proton transfer in the electronic ground state of chloromalonaldehyde: an ab initio study of time-resolved photoelectron spectra.

PubMed

do N Varella, Márcio T; Arasaki, Yasuki; Ushiyama, Hiroshi; Takatsuka, Kazuo; Wang, Kwanghsi; McKoy, Vincent

2007-02-07

The authors report on studies of time-resolved photoelectron spectra of intramolecular proton transfer in the ground state of chloromalonaldehyde, employing ab initio photoionization matrix elements and effective potential surfaces of reduced dimensionality, wherein the couplings of proton motion to the other molecular vibrational modes are embedded by averaging over classical trajectories. In the simulations, population is transferred from the vibrational ground state to vibrationally hot wave packets by pumping to an excited electronic state and dumping with a time-delayed pulse. These pump-dump-probe simulations demonstrate that the time-resolved photoelectron spectra track proton transfer in the electronic ground state well and, furthermore, that the geometry dependence of the matrix elements enhances the tracking compared with signals obtained with the Condon approximation. Photoelectron kinetic energy distributions arising from wave packets localized in different basins are also distinguishable and could be understood, as expected, on the basis of the strength of the optical couplings in different regions of the ground state potential surface and the Franck-Condon overlaps of the ground state wave packets with the vibrational eigenstates of the ion potential surface.

Strong ground motion prediction using virtual earthquakes.

PubMed

Denolle, M A; Dunham, E M; Prieto, G A; Beroza, G C

2014-01-24

Sedimentary basins increase the damaging effects of earthquakes by trapping and amplifying seismic waves. Simulations of seismic wave propagation in sedimentary basins capture this effect; however, there exists no method to validate these results for earthquakes that have not yet occurred. We present a new approach for ground motion prediction that uses the ambient seismic field. We apply our method to a suite of magnitude 7 scenario earthquakes on the southern San Andreas fault and compare our ground motion predictions with simulations. Both methods find strong amplification and coupling of source and structure effects, but they predict substantially different shaking patterns across the Los Angeles Basin. The virtual earthquake approach provides a new approach for predicting long-period strong ground motion.

Thunder-induced ground motions: 1. Observations

NASA Astrophysics Data System (ADS)

Lin, Ting-L.; Langston, Charles A.

2009-04-01

Acoustic pressure from thunder and its induced ground motions were investigated using a small array consisting of five three-component short-period surface seismometers, a three-component borehole seismometer, and five infrasound microphones. We used the array to constrain wave parameters of the incident acoustic and seismic waves. The incident slowness differences between acoustic pressure and ground motions suggest that ground reverberations were first initiated somewhat away from the array. Using slowness inferred from ground motions is preferable to obtain the seismic source parameters. We propose a source equalization procedure for acoustic/seismic deconvolution to generate the time domain transfer function, a procedure similar to that of obtaining teleseismic earthquake receiver functions. The time domain transfer function removes the incident pressure time history from the seismogram. An additional vertical-to-radial ground motion transfer function was used to identify the Rayleigh wave propagation mode of induced seismic waves complementing that found using the particle motions and amplitude variations in the borehole. The initial motions obtained by the time domain transfer functions suggest a low Poisson's ratio for the near-surface layer. The acoustic-to-seismic transfer functions show a consistent reverberation series at frequencies near 5 Hz. This gives an empirical measure of site resonance that depends on the ratio of the layer velocity to layer thickness for earthquake P and S waves. The time domain transfer function approach by transferring a spectral division into the time domain provides an alternative method for studying acoustic-to-seismic coupling.

Estimation of ground motion parameters

USGS Publications Warehouse

Boore, David M.; Joyner, W.B.; Oliver, A.A.; Page, R.A.

1978-01-01

Strong motion data from western North America for earthquakes of magnitude greater than 5 are examined to provide the basis for estimating peak acceleration, velocity, displacement, and duration as a function of distance for three magnitude classes. A subset of the data (from the San Fernando earthquake) is used to assess the effects of structural size and of geologic site conditions on peak motions recorded at the base of structures. Small but statistically significant differences are observed in peak values of horizontal acceleration, velocity and displacement recorded on soil at the base of small structures compared with values recorded at the base of large structures. The peak acceleration tends to b3e less and the peak velocity and displacement tend to be greater on the average at the base of large structures than at the base of small structures. In the distance range used in the regression analysis (15-100 km) the values of peak horizontal acceleration recorded at soil sites in the San Fernando earthquake are not significantly different from the values recorded at rock sites, but values of peak horizontal velocity and displacement are significantly greater at soil sites than at rock sites. Some consideration is given to the prediction of ground motions at close distances where there are insufficient recorded data points. As might be expected from the lack of data, published relations for predicting peak horizontal acceleration give widely divergent estimates at close distances (three well known relations predict accelerations between 0.33 g to slightly over 1 g at a distance of 5 km from a magnitude 6.5 earthquake). After considering the physics of the faulting process, the few available data close to faults, and the modifying effects of surface topography, at the present time it would be difficult to accept estimates less than about 0.8 g, 110 cm/s, and 40 cm, respectively, for the mean values of peak acceleration, velocity, and displacement at rock sites within 5 km of fault rupture in a magnitude 6.5 earthquake. These estimates can be expected to change as more data become available.

Seismic‐wave attenuation determined from tectonic tremor in multiple subduction zones

USGS Publications Warehouse

Yabe, Suguru; Baltay, Annemarie S.; Ide, Satoshi; Beroza, Gregory C.

2014-01-01

Tectonic tremor provides a new source of observations that can be used to constrain the seismic attenuation parameter for ground‐motion prediction and hazard mapping. Traditionally, recorded earthquakes of magnitude ∼3–8 are used to develop ground‐motion prediction equations; however, typical earthquake records may be sparse in areas of high hazard. In this study, we constrain the distance decay of seismic waves using measurements of the amplitude decay of tectonic tremor, which is plentiful in some regions. Tectonic tremor occurs in the frequency band of interest for ground‐motion prediction (i.e., ∼2–8  Hz) and is located on the subducting plate interface, at the lower boundary of where future large earthquakes are expected. We empirically fit the distance decay of peak ground velocity from tremor to determine the attenuation parameter in four subduction zones: Nankai, Japan; Cascadia, United States–Canada; Jalisco, Mexico; and southern Chile. With the large amount of data available from tremor, we show that in the upper plate, the lower crust is less attenuating than the upper crust. We apply the same analysis to intraslab events in Nankai and show the possibility that waves traveling from deeper intraslab events experience more attenuation than those from the shallower tremor due to ray paths that pass through the subducting and highly attenuating oceanic crust. This suggests that high pore‐fluid pressure is present in the tremor source region. These differences imply that the attenuation parameter determined from intraslab earthquakes may underestimate ground motion for future large earthquakes on the plate interface.

Ground Motion Studies for Large Future Accelerator

NASA Astrophysics Data System (ADS)

Takeda, Shigeru; Oide, Katsunobu

1997-05-01

The future large accelerator, such as TeV linear collider, should have extremely small emittance to perform the required luminosity. Precise alignment of machine components is essential to prevent emittance dilution. The ground motion spoils alignment of accelerator elements and results in emittance growth. The ground motion in the frequency range of seismic vibration is mostly coherent in the related accelerator. But the incoherent diffusive or Brownian like motion becomes dominant at frequency region less than seismic vibration [1, 2, 3]. Slow ground motion with respect to the machine performance is discussed including the method of tunnel construction. Our experimental results and recent excavated results clarify that application of TBMs is better excavating method than NATM (Drill + Blast) for accelerator tunnel to prevent emittance dilution. ([1] V. Shiltsev, Proc. of IWAA95 Tsukuba, 1995. [2] Shigeru Takeda et al., Proc. of EPAC96, 1996. [3] A. Sery, Proc. of LINAC96, 1996.)

Seismicity in the block mountains between Halle and Leipzig, Central Germany: centroid moment tensors, ground motion simulation, and felt intensities of two M ≈ 3 earthquakes in 2015 and 2017

NASA Astrophysics Data System (ADS)

Dahm, Torsten; Heimann, Sebastian; Funke, Sigward; Wendt, Siegfried; Rappsilber, Ivo; Bindi, Dino; Plenefisch, Thomas; Cotton, Fabrice

2018-05-01

On April 29, 2017 at 0:56 UTC (2:56 local time), an M W = 2.8 earthquake struck the metropolitan area between Leipzig and Halle, Germany, near the small town of Markranstädt. The earthquake was felt within 50 km from the epicenter and reached a local intensity of I 0 = IV. Already in 2015 and only 15 km northwest of the epicenter, a M W = 3.2 earthquake struck the area with a similar large felt radius and I 0 = IV. More than 1.1 million people live in the region, and the unusual occurrence of the two earthquakes led to public attention, because the tectonic activity is unclear and induced earthquakes have occurred in neighboring regions. Historical earthquakes south of Leipzig had estimated magnitudes up to M W ≈ 5 and coincide with NW-SE striking crustal basement faults. We use different seismological methods to analyze the two recent earthquakes and discuss them in the context of the known tectonic structures and historical seismicity. Novel stochastic full waveform simulation and inversion approaches are adapted for the application to weak, local earthquakes, to analyze mechanisms and ground motions and their relation to observed intensities. We find NW-SE striking normal faulting mechanisms for both earthquakes and centroid depths of 26 and 29 km. The earthquakes are located where faults with large vertical offsets of several hundred meters and Hercynian strike have developed since the Mesozoic. We use a stochastic full waveform simulation to explain the local peak ground velocities and calibrate the method to simulate intensities. Since the area is densely populated and has sensitive infrastructure, we simulate scenarios assuming that a 12-km long fault segment between the two recent earthquakes is ruptured and study the impact of rupture parameters on ground motions and expected damage.

The Las Vegas Valley Seismic Response Project: Ground Motions in Las Vegas Valley from Nuclear Explosions at the Nevada Test Site

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

Rodgers, A; Tkalcic, H; McCallen, D

2005-03-18

Between 2001-2004 the Las Vegas Seismic Response Project has sought to understand the response of Las Vegas Valley (LVV) to seismic excitation. In this study, the author report the findings of this project with an emphasis on ground motions in LVV from nuclear explosions at the Nevada Test Site (NTS). These ground motions are used to understand building structural response and damage as well as human perception. Historical nuclear explosion observations are augmented with earthquake recordings from a temporary deployment of seismometers to improve spatial coverage of LVV. The nuclear explosions were conducted between 1968 and 1989 and were recordedmore » at various sites within Las Vegas. The data from past nuclear tests were used to constrain ground motions in LVV and to gain a predictive capability of ground motions for possible future nuclear tests at NTS. Analysis of ground motion data includes peak ground motions (accelerations and velocities) and amplification of basin sites relative to hard rock sites (site response). Site response was measured with the Standard Spectral Ratios (SSR) technique relative to hard rock reference sites on the periphery of LVV. The site response curves indicate a strong basin amplification of up to a factor of ten at frequencies between 0.5-2 Hz. Amplifications are strongest in the central and northern portions of LVV, where the basin is deeper than 1 km based on the reported basin depths of Langenheim et al (2001a). They found a strong correlation between amplification and basin depth and shallow shear wave velocities. Amplification below 1 Hz is strongly controlled by slowness-averaged shear velocities to depths of 30 and 100 meters. Depth averaged shear velocities to 10 meters has modest control of amplifications between 1-3 Hz. Modeling reveals that low velocity material in the shallow layers (< 200 m) effectively controls amplification. They developed a method to scale nuclear explosion ground motion time series to sites around LVV that have no historical record of explosions. The method is also used to scale nuclear explosion ground motions to different yields. They also present a range of studies to understand basin structure and response performed on data from the temporary deployment.« less

Strike-slip earthquakes can also be detected in the ionosphere

NASA Astrophysics Data System (ADS)

Astafyeva, Elvira; Rolland, Lucie M.; Sladen, Anthony

2014-11-01

It is generally assumed that co-seismic ionospheric disturbances are generated by large vertical static displacements of the ground during an earthquake. Consequently, it is expected that co-seismic ionospheric disturbances are only observable after earthquakes with a significant dip-slip component. Therefore, earthquakes dominated by strike-slip motion, i.e. with very little vertical co-seismic component, are not expected to generate ionospheric perturbations. In this work, we use total electron content (TEC) measurements from ground-based GNSS-receivers to study ionospheric response to six recent largest strike-slip earthquakes: the Mw7.8 Kunlun earthquake of 14 November 2001, the Mw8.1 Macquarie earthquake of 23 December 2004, the Sumatra earthquake doublet, Mw8.6 and Mw8.2, of 11 April 2012, the Mw7.7 Balochistan earthquake of 24 September 2013 and the Mw 7.7 Scotia Sea earthquake of 17 November 2013. We show that large strike-slip earthquakes generate large ionospheric perturbations of amplitude comparable with those induced by dip-slip earthquakes of equivalent magnitude. We consider that in the absence of significant vertical static co-seismic displacements of the ground, other seismological parameters (primarily the magnitude of co-seismic horizontal displacements, seismic fault dimensions, seismic slip) may contribute in generation of large-amplitude ionospheric perturbations.

Application of Gumbel I and Monte Carlo methods to assess seismic hazard in and around Pakistan

NASA Astrophysics Data System (ADS)

Rehman, Khaista; Burton, Paul W.; Weatherill, Graeme A.

2018-05-01

A proper assessment of seismic hazard is of considerable importance in order to achieve suitable building construction criteria. This paper presents probabilistic seismic hazard assessment in and around Pakistan (23° N-39° N; 59° E-80° E) in terms of peak ground acceleration (PGA). Ground motion is calculated in terms of PGA for a return period of 475 years using a seismogenic-free zone method of Gumbel's first asymptotic distribution of extreme values and Monte Carlo simulation. Appropriate attenuation relations of universal and local types have been used in this study. The results show that for many parts of Pakistan, the expected seismic hazard is relatively comparable with the level specified in the existing PGA maps.

Time Crystal Behavior of Excited Eigenstates

NASA Astrophysics Data System (ADS)

Syrwid, Andrzej; Zakrzewski, Jakub; Sacha, Krzysztof

2017-12-01

In analogy to spontaneous breaking of continuous space translation symmetry in the process of space crystal formation, it was proposed that spontaneous breaking of continuous time translation symmetry could lead to time crystal formation. In other words, a time-independent system prepared in the energy ground state is expected to reveal periodic motion under infinitely weak perturbation. In the case of the system proposed originally by Wilczek, spontaneous breaking of time translation symmetry cannot be observed if one starts with the ground state. We point out that the symmetry breaking can take place if the system is prepared in an excited eigenstate. The latter can be realized experimentally in ultracold atomic gases. We simulate the process of the spontaneous symmetry breaking due to measurements of particle positions and analyze the lifetime of the resulting symmetry broken state.

Time Crystal Behavior of Excited Eigenstates.

PubMed

Syrwid, Andrzej; Zakrzewski, Jakub; Sacha, Krzysztof

2017-12-22

In analogy to spontaneous breaking of continuous space translation symmetry in the process of space crystal formation, it was proposed that spontaneous breaking of continuous time translation symmetry could lead to time crystal formation. In other words, a time-independent system prepared in the energy ground state is expected to reveal periodic motion under infinitely weak perturbation. In the case of the system proposed originally by Wilczek, spontaneous breaking of time translation symmetry cannot be observed if one starts with the ground state. We point out that the symmetry breaking can take place if the system is prepared in an excited eigenstate. The latter can be realized experimentally in ultracold atomic gases. We simulate the process of the spontaneous symmetry breaking due to measurements of particle positions and analyze the lifetime of the resulting symmetry broken state.

A comparative study of ground motion hybrid simulations and the modified NGA ground motion predictive equations for directivity and its application to the the Marmara Sea region (Turkey)

NASA Astrophysics Data System (ADS)

Pischiutta, M.; Akinci, A.; Spagnuolo, E.; Taroni, M.; Herrero, A.; Aochi, H.

2016-12-01

We have simulated strong ground motions for two Mw>7.0 rupture scenarios on the North Anatolian Fault, in the Marmara Sea within 10-20 km from Istanbul. This city is characterized by one of the highest levels of seismic risk in Europe and the Mediterranean region. The increased risk in Istanbul is due to eight destructive earthquakes that ruptured the fault system and left a seismic gap at the western portion of the 1000km-long North Anatolian Fault Zone. To estimate the ground motion characteristics and its variability in the region we have simulated physics-based rupture scenarios, producing hybrid broadband time histories. We have merged two simulation techniques: a full 3D wave propagation method to generate low-frequency seismograms (Aochi and Ulrich, 2015) and the stochastic finite-fault model approach based on a dynamic corner frequency (Motazedian and Atkinson, 2005) to simulate high-frequency seismograms (Akinci et al., 2016, submitted to BSSA, 2016). They are merged to compute realistic broadband hybrid time histories. The comparison of ground motion intensity measures (PGA, PGV, SA) resulting from our simulations with those predicted by the recent Ground Motion Prediction Equations (GMPEs) in the region (Boore & Atkinson, 2008; Chiou & Young, 2008; Akkar & Bommer, 2010; Akkar & Cagnan, 2010) seems to indicate that rupture directivity and super-shear rupture effects affect the ground motion in the Marmara Sea region. In order to account for the rupture directivity we improve the comparison using the directivity predictor proposed by Spudich & Chiu (2008). This study highlights the importance of the rupture directivity for the hazard estimation in the Marmara Sea region, especially for the city of Istanbul.

Nonlinear coseismic infrasound waves in the upper atmosphere and ionosphere

NASA Astrophysics Data System (ADS)

Chum, J.; Liu, J. Y.; Cabrera, M. A.

2017-12-01

Vertical motion of the ground surface caused by seismic waves generates acoustic waves that propagate nearly vertically upward because of supersonic speed of seismic waves. As the air density decreases with height, the amplitude of acoustic waves increases to conserve the energy flux. If the initial perturbation is large enough (larger than 10 mm/s) and the period of waves is long (>10 s), then the amplitude reaches significant values in the upper atmosphere (e.g. oscillation velocities of the air particles become comparable with sound speed) and the nonlinear phenomena start to play an important role before the wave is dissipated. The nonlinear phenomena lead to changes of spectral content of the wave packet. The energy is transferred to lower frequencies, which can cause the formation of roughly bipolar N-shaped pulse in the vicinity of the epicenters (up to distance about 1000-1500 km) of strong, M>7, earthquakes. The nonlinear propagation is studied on the basis of numerical solution of continuity, momentum and heat equations in 1D (along vertical axis) for viscous compressible atmosphere. Boundary conditions on the ground are determined by real measurements of the vertical motion of the ground surface. The results of numerical simulations are in a good agreement with atmospheric fluctuations observed by continuous Doppler sounding at heights of about 200 km and epicenter distance around 800 km. In addition, the expected fluctuations of GSP-TEC are calculated.

Spatial correlation of probabilistic earthquake ground motion and loss

USGS Publications Warehouse

Wesson, R.L.; Perkins, D.M.

2001-01-01

Spatial correlation of annual earthquake ground motions and losses can be used to estimate the variance of annual losses to a portfolio of properties exposed to earthquakes A direct method is described for the calculations of the spatial correlation of earthquake ground motions and losses. Calculations for the direct method can be carried out using either numerical quadrature or a discrete, matrix-based approach. Numerical results for this method are compared with those calculated from a simple Monte Carlo simulation. Spatial correlation of ground motion and loss is induced by the systematic attenuation of ground motion with distance from the source, by common site conditions, and by the finite length of fault ruptures. Spatial correlation is also strongly dependent on the partitioning of the variability, given an event, into interevent and intraevent components. Intraevent variability reduces the spatial correlation of losses. Interevent variability increases spatial correlation of losses. The higher the spatial correlation, the larger the variance in losses to a port-folio, and the more likely extreme values become. This result underscores the importance of accurately determining the relative magnitudes of intraevent and interevent variability in ground-motion studies, because of the strong impact in estimating earthquake losses to a portfolio. The direct method offers an alternative to simulation for calculating the variance of losses to a portfolio, which may reduce the amount of calculation required.

Recent updates in developing a statistical pseudo-dynamic source-modeling framework to capture the variability of earthquake rupture scenarios

NASA Astrophysics Data System (ADS)

Song, Seok Goo; Kwak, Sangmin; Lee, Kyungbook; Park, Donghee

2017-04-01

It is a critical element to predict the intensity and variability of strong ground motions in seismic hazard assessment. The characteristics and variability of earthquake rupture process may be a dominant factor in determining the intensity and variability of near-source strong ground motions. Song et al. (2014) demonstrated that the variability of earthquake rupture scenarios could be effectively quantified in the framework of 1-point and 2-point statistics of earthquake source parameters, constrained by rupture dynamics and past events. The developed pseudo-dynamic source modeling schemes were also validated against the recorded ground motion data of past events and empirical ground motion prediction equations (GMPEs) at the broadband platform (BBP) developed by the Southern California Earthquake Center (SCEC). Recently we improved the computational efficiency of the developed pseudo-dynamic source-modeling scheme by adopting the nonparametric co-regionalization algorithm, introduced and applied in geostatistics initially. We also investigated the effect of earthquake rupture process on near-source ground motion characteristics in the framework of 1-point and 2-point statistics, particularly focusing on the forward directivity region. Finally we will discuss whether the pseudo-dynamic source modeling can reproduce the variability (standard deviation) of empirical GMPEs and the efficiency of 1-point and 2-point statistics to address the variability of ground motions.

Tilts in strong ground motion

USGS Publications Warehouse

Graizer, V.

2006-01-01

Most instruments used in seismological practice to record ground motion are pendulum seismographs, velocigraphs, or accelerographs. In most cases it is assumed that seismic instruments are only sensitive to the translational motion of the instrument's base. In this study the full equation of pendulum motion, including the inputs of rotations and tilts, is considered. It is shown that tilting the accelerograph's base can severely impact its response to the ground motion. The method of tilt evaluation using uncorrected strong-motion accelerograms was first suggested by Graizer (1989), and later tested in several laboratory experiments with different strong-motion instruments. The method is based on the difference in the tilt sensitivity of the horizontal and vertical pendulums. The method was applied to many of the strongest records of the Mw 6.7 Northridge earthquake of 1994. Examples are shown when relatively large tilts of up to a few degrees occurred during strong earthquake ground motion. Residual tilt extracted from the strong-motion record at the Pacoima Dam-Upper Left Abutment reached 3.1?? in N45??E direction, and was a result of local earthquake-induced tilting due to high-amplitude shaking. This value is in agreement with the residual tilt measured by using electronic level a few days after the earthquake. The method was applied to the building records from the Northridge earthquake. According to the estimates, residual tilt reached 2.6?? on the ground floor of the 12-story Hotel in Ventura. Processing of most of the strongest records of the Northridge earthquake shows that tilts, if happened, were within the error of the method, or less than about 0.5??.

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.

Ground-motion parameters of the southwestern Indiana earthquake of 18 June 2002 and the disparity between the observed and predicted values

USGS Publications Warehouse

Street, R.; Wiegand, J.; Woolery, E.W.; Hart, P.

2005-01-01

The M 4.5 southwestern Indiana earthquake of 18 June 2002 triggered 46 blast monitors in Indiana, Illinois, and Kentucky. The resulting free-field particle velocity records, along with similar data from previous earthquakes in the study area, provide a clear standard for judging the reliability of current maps for predicting ground motions greater than 2 Hz in southwestern Indiana and southeastern Illinois. Peak horizontal accelerations and velocities, and 5% damped pseudo-accelerations for the earthquake, generally exceeded ground motions predicted for the top of the bedrock by factors of 2 or more, even after soil amplifications were taken into consideration. It is suggested, but not proven, that the low shear-wave velocity and weathered bedrock in the area are also amplifying the higher-frequency ground motions that have been repeatedly recorded by the blast monitors in the study area. It is also shown that there is a good correlation between the peak ground motions and 5% pseudo-accelerations recorded for the event, and the Modified Mercalli intensities interpreted for the event by the U.S. Geological Survey.

Evaluation of the recorded ground motions for the unusual earthquake of 13 August 2006 ( M w 5.3) in Michoacán México

NASA Astrophysics Data System (ADS)

Ramírez-Gaytán, Alejandro; Jaimes, Miguel A.; Bandy, William L.; Huerfano, Victor M.; Salido-Ruiz, Ricardo A.

2015-10-01

The focal mechanism of the moderate earthquake of 13 August 2006 M w = 5.3, which occurred in the border coastal area between Michoacán and Colima, México, is unusual. As shown by the Global Centroid Moment Tensor (CMT) project and the Servicio Sismológico Nacional de Mexico (SSN), the thrust mechanism is striking almost perpendicularly to the majority of earthquakes occurring along the subduction zone of the Mexican Pacific continental margin which commonly strike nearly parallel to the trench. The purpose of this study is to analyze the observed ground motions of this particular event relative to those of the common events. First, we apply the H/V technique to verify that the stations involved in this study are nearly free of site effects. Then, we compare the observed ground motions with (i) three empirical ground motion prediction equations (GMPEs) appropriate for the region, (ii) ground motions of four real earthquakes with the common mechanism, and (iii) the Fourier spectrum of a selected common event.

Physics-based real time ground motion parameter maps: the Central Mexico example

NASA Astrophysics Data System (ADS)

Ramirez Guzman, L.; Contreras Ruiz Esparza, M. G.; Quiroz Ramirez, A.; Carrillo Lucia, M. A.; Perez Yanez, C.

2013-12-01

We present the use of near real time ground motion simulations in the generation of ground motion parameter maps for Central Mexico. Simple algorithm approaches to predict ground motion parameters of civil protection and risk engineering interest are based on the use of observed instrumental values, reported macroseismic intensities and their correlations, and ground motion prediction equations (GMPEs). A remarkable example of the use of this approach is the worldwide Shakemap generation program of the United States Geological Survey (USGS). Nevertheless, simple approaches rely strongly on the availability of instrumental and macroseismic intensity reports, as well as the accuracy of the GMPEs and the site effect amplification calculation. In regions where information is scarce, the GMPEs, a reference value in a mean sense, provide most of the ground motion information together with site effects amplification using a simple parametric approaches (e.g. the use of Vs30), and have proven to be elusive. Here we propose an approach that includes physics-based ground motion predictions (PBGMP) corrected by instrumental information using a Bayesian Kriging approach (Kitanidis, 1983) and apply it to the central region of Mexico. The method assumes: 1) the availability of a large database of low and high frequency Green's functions developed for the region of interest, using fully three-dimensional and representative one-dimension models, 2) enough real time data to obtain the centroid moment tensor and a slip rate function, and 3) a computational infrastructure that can be used to compute the source parameters and generate broadband synthetics in near real time, which will be combined with recorded instrumental data. By using a recently developed velocity model of Central Mexico and an efficient finite element octree-based implementation we generate a database of source-receiver Green's functions, valid to 0.5 Hz, that covers 160 km x 300 km x 700 km of Mexico, including a large portion of the Pacific Mexican subduction zone. A subset of the velocity and strong ground motion data available in real time is processed to obtain the source parameters to generate broadband ground motions in a dense grid ( 10 km x 10 km cells). These are interpolated later with instrumental values using a Bayesian Kriging method. Peak ground velocity and acceleration, as well as SA (T=0.1, 0.5, 1 and 2s) maps, are generated for a small set of medium to large magnitude Mexican earthquakes (Mw=5 to 7.4). We evaluate each map by comparing against stations not considered in the computation.

Figure-ground segregation modulates apparent motion.

PubMed

Ramachandran, V S; Anstis, S

1986-01-01

We explored the relationship between figure-ground segmentation and apparent motion. Results suggest that: static elements in the surround can eliminate apparent motion of a cluster of dots in the centre, but only if the cluster and surround have similar "grain" or texture; outlines that define occluding surfaces are taken into account by the motion mechanism; the brain uses a hierarchy of precedence rules in attributing motion to different segments of the visual scene. Being designated as "figure" confers a high rank in this scheme of priorities.

Review of Seismic Hazard Issues Associated with Auburn Dam Project, Sierra Nevada Foothills, California

USGS Publications Warehouse

Schwartz, D.P.; Joyner, W.B.; Stein, R.S.; Brown, R.D.; McGarr, A.F.; Hickman, S.H.; Bakun, W.H.

1996-01-01

Summary -- The U.S. Geological Survey was requested by the U.S. Department of the Interior to review the design values and the issue of reservoir-induced seismicity for a concrete gravity dam near the site of the previously-proposed Auburn Dam in the western foothills of the Sierra Nevada, central California. The dam is being planned as a flood-control-only dam with the possibility of conversion to a permanent water-storage facility. As a basis for planning studies the U.S. Army Corps of Engineers is using the same design values approved by the Secretary of the Interior in 1979 for the original Auburn Dam. These values were a maximum displacement of 9 inches on a fault intersecting the dam foundation, a maximum earthquake at the site of magnitude 6.5, a peak horizontal acceleration of 0.64 g, and a peak vertical acceleration of 0.39 g. In light of geological and seismological investigations conducted in the western Sierran foothills since 1979 and advances in the understanding of how earthquakes are caused and how faults behave, we have developed the following conclusions and recommendations: Maximum Displacement. Neither the pre-1979 nor the recent observations of faults in the Sierran foothills precisely define the maximum displacement per event on a fault intersecting the dam foundation. Available field data and our current understanding of surface faulting indicate a range of values for the maximum displacement. This may require the consideration of a design value larger than 9 inches. We recommend reevaluation of the design displacement using current seismic hazard methods that incorporate uncertainty into the estimate of this design value. Maximum Earthquake Magnitude. There are no data to indicate that a significant change is necessary in the use of an M 6.5 maximum earthquake to estimate design ground motions at the dam site. However, there is a basis for estimating a range of maximum magnitudes using recent field information and new statistical fault relations. We recommend reevaluating the maximum earthquake magnitude using current seismic hazard methodology. Design Ground Motions. A large number of strong-motion records have been acquired and significant advances in understanding of ground motion have been achieved since the original evaluations. The design value for peak horizontal acceleration (0.64 g) is larger than the median of one recent study and smaller than the median value of another. The value for peak vertical acceleration (0.39 g) is somewhat smaller than median values of two recent studies. We recommend a reevaluation of the design ground motions that takes into account new ground motion data with particular attention to rock sites at small source distances. Reservoir-Induced Seismicity. The potential for reservoir-induced seismicity must be considered for the Auburn Darn project. A reservoir-induced earthquake is not expected to be larger than the maximum naturally occurring earthquake. However, the probability of an earthquake may be enhanced by reservoir impoundment. A flood-control-only project may involve a lower probability of significant induced seismicity than a multipurpose water-storage dam. There is a need to better understand and quantify the likelihood of this hazard. A methodology should be developed to quantify the potential for reservoir induced seismicity using seismicity data from the Sierran foothills, new worldwide observations of induced and triggered seismicity, and current understanding of the earthquake process. Reevaluation of Design Parameters. The reevaluation of the maximum displacement, maximum magnitude earthquake, and design ground motions can be made using available field observations from the Sierran foothills, updated statistical relations for faulting and ground motions, and current computational seismic hazard methodologies that incorporate uncertainty into the analysis. The reevaluation does not require significant new geological field studies.

Source parameters of the 2013 Lushan, Sichuan, Ms7.0 earthquake and estimation of the near-fault strong ground motion

NASA Astrophysics Data System (ADS)

Meng, L.; Zhou, L.; Liu, J.

2013-12-01

Abstract: The April 20, 2013 Ms 7.0 earthquake in Lushan city, Sichuan province of China occurred as the result of east-west oriented reverse-type motion on a north-south striking fault. The source location suggests the event occurred on the Southern part of Longmenshan fault at a depth of 13km. The Lushan earthquake caused a great of loss of property and 196 deaths. The maximum intensity is up to VIII to IX at Boxing and Lushan city, which are located in the meizoseismal area. In this study, we analyzed the dynamic source process and calculated source spectral parameters, estimated the strong ground motion in the near-fault field based on the Brune's circle model at first. A dynamical composite source model (DCSM) has been developed further to simulate the near-fault strong ground motion with associated fault rupture properties at Boxing and Lushan city, respectively. The results indicate that the frictional undershoot behavior in the dynamic source process of Lushan earthquake, which is actually different from the overshoot activity of the Wenchuan earthquake. Based on the simulated results of the near-fault strong ground motion, described the intensity distribution of the Lushan earthquake field. The simulated intensity indicated that, the maximum intensity value is IX, and region with and above VII almost 16,000km2, which is consistence with observation intensity published online by China Earthquake Administration (CEA) on April 25. Moreover, the numerical modeling developed in this study has great application in the strong ground motion prediction and intensity estimation for the earthquake rescue purpose. In fact, the estimation methods based on the empirical relationship and numerical modeling developed in this study has great application in the strong ground motion prediction for the earthquake source process understand purpose. Keywords: Lushan, Ms7.0 earthquake; near-fault strong ground motion; DCSM; simulated intensity

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.

TEMPUS: A facility for containerless electromagnetic processing onboard spacelab

NASA Technical Reports Server (NTRS)

Lenski, H.; Willnecker, R.

1990-01-01

The electromagnetic containerless processing facility TEMPUS was recently assigned for a flight on the IML-2 mission. In comparison to the TEMPUS facility already flown on a sounding rocket, several improvements had to be implemented. These are in particular related to: safety; resource management; and the possibility to process different samples with different requirements in one mission. The basic design of this facility as well as the expected processing capabilities are presented. Two operational aspects turned out to strongly influence the facility design: control of the sample motion (first experimental results indicate that crew or ground interaction will be necessary to minimize residual sample motions during processing); and exchange of RF-coils (during processing in vacuum, evaporated sample materials will condense at the cold surface and may force a coil exchange, when a critical thickness is exceeded).

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.

Source parameters of the 2013, Ms 7.0, Lushan earthquake and the characteristics of the near-fault strong ground motion

NASA Astrophysics Data System (ADS)

Zhao, Fengfan; Meng, Lingyuan

2016-04-01

The April 20, 2013 Ms 7.0, earthquake in Lushan city, Sichuan province of China occurred as the result of east-west oriented reverse-type motion on a north-south striking fault. The source location suggests the event occurred on the Southern part of Longmenshan fault at a depth of 13km. The maximum intensity is up to VIII to IX at Boxing and Lushan city, which are located in the meizoseismal area. In this study, we analyzed the dynamic source process with the source mechanism and empirical relationships, estimated the strong ground motion in the near-fault field based on the Brune's circle model. A dynamical composite source model (DCSM) has been developed to simulate the near-fault strong ground motion with associated fault rupture properties at Boxing and Lushan city, respectively. The results indicate that the frictional undershoot behavior in the dynamic source process of Lushan earthquake, which is actually different from the overshoot activity of the Wenchuan earthquake. Moreover, we discussed the characteristics of the strong ground motion in the near-fault field, that the broadband synthetic seismogram ground motion predictions for Boxing and Lushan city produced larger peak values, shorter durations and higher frequency contents. It indicates that the factors in near-fault strong ground motion was under the influence of higher effect stress drop and asperity slip distributions on the fault plane. This work is financially supported by the Natural Science Foundation of China (Grant No. 41404045) and by Science for Earthquake Resilience of CEA (XH14055Y).

Chapter D. The Loma Prieta, California, Earthquake of October 17, 1989 - Earth Structures and Engineering Characterization of Ground Motion

USGS Publications Warehouse

Holzer, Thomas L.

1998-01-01

This chapter contains two papers that summarize the performance of engineered earth structures, dams and stabilized excavations in soil, and two papers that characterize for engineering purposes the attenuation of ground motion with distance during the Loma Prieta earthquake. Documenting the field performance of engineered structures and confirming empirically based predictions of ground motion are critical for safe and cost effective seismic design of future structures as well as the retrofitting of existing ones.

10 CFR 72.103 - Geological and seismological characteristics for applications for dry cask modes of storage on or...

Code of Federal Regulations, 2010 CFR

2010-01-01

..., and that are not in areas of known seismic activity, a standardized design earthquake ground motion... motion, tectonic surface deformation, nontectonic deformation, earthquake recurrence rates, fault... of the Design Earthquake Ground Motion (DE). The DE for the site is characterized by both horizontal...

10 CFR 72.103 - Geological and seismological characteristics for applications for dry cask modes of storage on or...

Code of Federal Regulations, 2011 CFR

2011-01-01

..., and that are not in areas of known seismic activity, a standardized design earthquake ground motion... motion, tectonic surface deformation, nontectonic deformation, earthquake recurrence rates, fault... of the Design Earthquake Ground Motion (DE). The DE for the site is characterized by both horizontal...

10 CFR 72.103 - Geological and seismological characteristics for applications for dry cask modes of storage on or...

Code of Federal Regulations, 2013 CFR

2013-01-01

..., and that are not in areas of known seismic activity, a standardized design earthquake ground motion... motion, tectonic surface deformation, nontectonic deformation, earthquake recurrence rates, fault... of the Design Earthquake Ground Motion (DE). The DE for the site is characterized by both horizontal...

10 CFR 72.103 - Geological and seismological characteristics for applications for dry cask modes of storage on or...

Code of Federal Regulations, 2014 CFR

2014-01-01

..., and that are not in areas of known seismic activity, a standardized design earthquake ground motion... motion, tectonic surface deformation, nontectonic deformation, earthquake recurrence rates, fault... of the Design Earthquake Ground Motion (DE). The DE for the site is characterized by both horizontal...

10 CFR 72.103 - Geological and seismological characteristics for applications for dry cask modes of storage on or...

Code of Federal Regulations, 2012 CFR

2012-01-01

..., and that are not in areas of known seismic activity, a standardized design earthquake ground motion... motion, tectonic surface deformation, nontectonic deformation, earthquake recurrence rates, fault... of the Design Earthquake Ground Motion (DE). The DE for the site is characterized by both horizontal...

Ground-Motion Prediction Equations (GMPEs) from a global dataset: the PEERPEER NGA equations

USGS Publications Warehouse

Boore, David M.; Akkar, Sinan; Gulkan, Polat; van Eck, Torild

2011-01-01

The PEER NGA ground-motion prediction equation s (GMPEs) were derived by five developer teams over several years, resulting in five sets of GMPEs. The teams used various subsets of a global database of ground motions and metadata from shallow earthquakes in tectonically active regions in the development of the equations. Since their publication, the predicted motions from these GMPEs have been compared with data from various parts of the world – data that largely were not used in the development of the GMPEs. The comparisons suggest that the NGA GMPEs are applicable globally for shallow earthquakes in tectonically active regions.

Upper and lower bounds of ground-motion variabilities: implication for source properties

NASA Astrophysics Data System (ADS)

Cotton, Fabrice; Reddy-Kotha, Sreeram; Bora, Sanjay; Bindi, Dino

2017-04-01

One of the key challenges of seismology is to be able to analyse the physical factors that control earthquakes and ground-motion variabilities. Such analysis is particularly important to calibrate physics-based simulations and seismic hazard estimations at high frequencies. Within the framework of the development of ground-motion prediction equation (GMPE) developments, ground-motions residuals (differences between recorded ground motions and the values predicted by a GMPE) are computed. The exponential growth of seismological near-source records and modern GMPE analysis technics allow to partition these residuals into between- and a within-event components. In particular, the between-event term quantifies all those repeatable source effects (e.g. related to stress-drop or kappa-source variability) which have not been accounted by the magnitude-dependent term of the model. In this presentation, we first discuss the between-event variabilities computed both in the Fourier and Response Spectra domains, using recent high-quality global accelerometric datasets (e.g. NGA-west2, Resorce, Kiknet). These analysis lead to the assessment of upper bounds for the ground-motion variability. Then, we compare these upper bounds with lower bounds estimated by analysing seismic sequences which occurred on specific fault systems (e.g., located in Central Italy or in Japan). We show that the lower bounds of between-event variabilities are surprisingly large which indicates a large variability of earthquake dynamic properties even within the same fault system. Finally, these upper and lower bounds of ground-shaking variability are discussed in term of variability of earthquake physical properties (e.g., stress-drop and kappa_source).

Spatial Based Integrated Assessment of Bedrock and Ground Motions, Fault Offsets, and Their Effects for the October-November 2002 Earthquake Sequence on the Denali Fault, Alaska

NASA Astrophysics Data System (ADS)

Vinson, T. S.; Carlson, R.; Hansen, R.; Hulsey, L.; Ma, J.; White, D.; Barnes, D.; Shur, Y.

2003-12-01

A National Science Foundation (NSF) Small Grant Exploratory Research Grant was awarded to the University of Alaska Fairbanks to archive bedrock and ground motions and fault offsets and their effects for the October-November 2002 earthquake sequence on the Denali Fault, Alaska. The scope of work included the accumulation of all strong motion records, satellite imagery, satellite remote sensing data, aerial and ground photographs, and structural response (both measured and anecdotal) that would be useful to achieve the objective. Several interesting data sets were archived including ice cover, lateral movement of stream channels, landslides, avalanches, glacial fracturing, "felt" ground motions, and changes in water quantity and quality. The data sources may be spatially integrated to provide a comprehensive assessment of the bedrock and ground motions and fault offsets for the October-November 2002 earthquake sequence. In the aftermath of the October-November 2002 earthquake sequence on the Denali fault, the Alaskan engineering community expressed a strong interest to understand why their structures and infrastructure were not substantially damaged by the ground motions they experienced during the October-November 2002 Earthquake Sequence on the Denali Fault. The research work proposed under this NSF Grant is a necessary prerequisite to this understanding. Furthermore, the proposed work will facilitate a comparison of Denali events with the Loma Prieta and recent Kocelli and Dozce events in Turkey, all of which were associated with strike-slip faulting. Finally, the spatially integrated data will provide the basis for research work that is truly innovative. For example, is may be possible to predict the observed (1) landsliding and avalanches, (2) changes in water quantity and quality, (3) glacial fracturing, and (4) the widespread liquefaction and lateral spreading, which occurred along the Tok cutoff and Northway airport, with the bedrock and ground motions and fault offsets extrapolated from the product of the research. An integrated assessment of the composite effects may be performed to better understand the bedrock and ground motions and fault offset regime that existed during the earthquake sequence.

Validation of the Passenger Ride Quality Apparatus (PRQA) for simulation of aircraft motions for ride-quality research

NASA Technical Reports Server (NTRS)

Bigler, W. B., II

1977-01-01

The NASA passenger ride quality apparatus (PRQA), a ground based motion simulator, was compared to the total in flight simulator (TIFS). Tests were made on PRQA with varying stimuli: motions only; motions and noise; motions, noise, and visual; and motions and visual. Regression equations for the tests were obtained and subsequent t-testing of the slopes indicated that ground based simulator tests produced comfort change rates similar to actual flight data. It was recommended that PRQA be used in the ride quality program for aircraft and that it be validated for other transportation modes.

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.

Probabilistic seismic demand analysis using advanced ground motion intensity measures

USGS Publications Warehouse

Tothong, P.; Luco, N.

2007-01-01

One of the objectives in performance-based earthquake engineering is to quantify the seismic reliability of a structure at a site. For that purpose, probabilistic seismic demand analysis (PSDA) is used as a tool to estimate the mean annual frequency of exceeding a specified value of a structural demand parameter (e.g. interstorey drift). This paper compares and contrasts the use, in PSDA, of certain advanced scalar versus vector and conventional scalar ground motion intensity measures (IMs). One of the benefits of using a well-chosen IM is that more accurate evaluations of seismic performance are achieved without the need to perform detailed ground motion record selection for the nonlinear dynamic structural analyses involved in PSDA (e.g. record selection with respect to seismic parameters such as earthquake magnitude, source-to-site distance, and ground motion epsilon). For structural demands that are dominated by a first mode of vibration, using inelastic spectral displacement (Sdi) can be advantageous relative to the conventionally used elastic spectral acceleration (Sa) and the vector IM consisting of Sa and epsilon (??). This paper demonstrates that this is true for ordinary and for near-source pulse-like earthquake records. The latter ground motions cannot be adequately characterized by either Sa alone or the vector of Sa and ??. For structural demands with significant higher-mode contributions (under either of the two types of ground motions), even Sdi (alone) is not sufficient, so an advanced scalar IM that additionally incorporates higher modes is used.

Identifying natural and anthropogenically-induced geohazards from satellite ground motion and geospatial data: Stoke-on-Trent, UK

NASA Astrophysics Data System (ADS)

Jordan, Hannah; Cigna, Francesca; Bateson, Luke

2017-12-01

Determining the location and nature of hazardous ground motion resulting from natural and anthropogenic processes such as landslides, tectonic movement and mining is essential for hazard mitigation and sustainable resource use. Ground motion estimates from satellite ERS-1/2 persistent scatterer interferometry (PSI) were combined with geospatial data to identify areas of observed geohazards in Stoke-on-Trent, UK. This investigation was performed within the framework of the EC FP7-SPACE PanGeo project which aimed to provide free and open access to geohazard information for 52 urban areas across Europe. Geohazards identified within the city of Stoke-on-Trent and neighbouring rural areas are presented here alongside an examination of the PanGeo methodology. A total of 14 areas experiencing ground instability caused by natural and anthropogenic processes have been defined, covering 122.35 km2. These are attributed to a range of geohazards, including landslides, ground dissolution, made ground and mining activities. The dominant geohazard (by area) is ground movement caused by post-mining groundwater recharge and mining-related subsidence (93.19% of total geohazard area), followed by landsliding (5.81%). Observed ground motions along the satellite line-of-sight reach maxima of +35.23 mm/yr and -22.57 mm/yr. A combination of uplift, subsidence and downslope movement is displayed. 'Construction sites' and 'continuous urban fabric' (European Urban Atlas land use types) form the land uses most affected (by area) by ground motion and 'discontinuous very low density urban fabric' the least. Areas of 'continuous urban fabric' also show the highest average velocity towards the satellite (5.08 mm/yr) and the highest PS densities (1262.92 points/km2) along with one of the lowest standard deviations. Rural land uses tend to result in lower PS densities and higher standard deviations, a consequence of fewer suitable reflectors in these regions. PSI is also limited in its ability to identify especially rapid ground motion. As a consequence the supporting geospatial data proved especially useful for the identification of landslides and some areas of ground dissolution. The mapped areas of instability are also compared with modelled potential geohazards (the BGS GeoSure dataset).

Establishment of Antakya Basin Strong Ground Motion Monitoring System

NASA Astrophysics Data System (ADS)

Durukal, E.; Özel, O.; Bikce, M.; Geneş, M. C.; Kacın, S.; Erdik, M.; Safak, E.; Över, S.

2009-04-01

Turkey is located in one of the most active earthquake zones of the world. The cities located along the North Anatolian Fault (NAF) and the East Anatolian Fault (EAF) are exposed to significant earthquake hazard. The Hatay province near the southern terminus of the EAF has always experienced a significant seismic activity, since it is on the intersection of the northernmost segment of Dead Sea Fault Zone coming from the south, with the Cyprean Arc approaching from south-west. Historical records extending over the last 2000 years indicate that Antakya, founded in the 3rd century B.C., is effected by intensity IX-X earthquakes every 150 years. In the region, the last destructive earthquake occurred in 1872. Destructive earthquakes should be expected in the region in the near future similar to the ones that occurred in the past. The strong response of sedimentary basins to seismic waves was largely responsible for the damage produced by the devastating earthquakes of 1985 Michoacan Earthquake which severely damaged parts of Mexico City, and the 1988 Spitak Earthquake which destroyed most of Leninakan, Armenia. Much of this devastating response was explained by the conversion of seismic body waves to surface waves at the sediment/rock contacts of sedimentary basins. "Antakya Basin Strong Ground Motion Monitoring System" is set up with the aim of monitoring the earthquake response of the Antakya Basin, contributing to our understanding of basin response, contributing to earthquake risk assessment of Antakya, monitoring of regional earthquakes and determining the effects of local and regional earthquakes on the urban environment of Antakya. The soil properties beneath the strong motion stations (S-Wave velocity structure and dominant soil frequency) are determined by array measurements that involve broad-band seismometers. The strong motion monitoring system consists of six instruments installed in small buildings. The stations form a straight line along the short axis of Antakya basin passing through the city center. They are equipped with acceleration sensors, GPS and communication units and operate in continuous recording mode. For on-line data transmission the EDGE mode of available GSM systems are employed. In the array measurements for the determination of soil properties beneath the stations two 4-seismometer sets have been utilized. The system is the first monitoring installment in Turkey dedicated to understanding basin effects. The records obtained will allow for the visualization of the propagation of long-period ground motion in the basin and show the refraction of surface waves at the basin edge. The records will also serve to enhance our capacity to realistically synthesize the strong ground motion in basin-type environments.

Real Time Earthquake Information System in Japan

NASA Astrophysics Data System (ADS)

Doi, K.; Kato, T.

2003-12-01

An early earthquake notification system in Japan had been developed by the Japan Meteorological Agency (JMA) as a governmental organization responsible for issuing earthquake information and tsunami forecasts. The system was primarily developed for prompt provision of a tsunami forecast to the public with locating an earthquake and estimating its magnitude as quickly as possible. Years after, a system for a prompt provision of seismic intensity information as indices of degrees of disasters caused by strong ground motion was also developed so that concerned governmental organizations can decide whether it was necessary for them to launch emergency response or not. At present, JMA issues the following kinds of information successively when a large earthquake occurs. 1) Prompt report of occurrence of a large earthquake and major seismic intensities caused by the earthquake in about two minutes after the earthquake occurrence. 2) Tsunami forecast in around three minutes. 3) Information on expected arrival times and maximum heights of tsunami waves in around five minutes. 4) Information on a hypocenter and a magnitude of the earthquake, the seismic intensity at each observation station, the times of high tides in addition to the expected tsunami arrival times in 5-7 minutes. To issue information above, JMA has established; - An advanced nationwide seismic network with about 180 stations for seismic wave observation and about 3,400 stations for instrumental seismic intensity observation including about 2,800 seismic intensity stations maintained by local governments, - Data telemetry networks via landlines and partly via a satellite communication link, - Real-time data processing techniques, for example, the automatic calculation of earthquake location and magnitude, the database driven method for quantitative tsunami estimation, and - Dissemination networks, via computer-to-computer communications and facsimile through dedicated telephone lines. JMA operationally monitors earthquake data and analyzes earthquake activities and tsunami occurrence round-the-clock on a real-time basis. In addition to the above, JMA has been developing a system of Nowcast Earthquake Information which can provide its users with occurrence of an earthquake prior to arrival of strong ground motion for a decade. Earthquake Research Institute, the University of Tokyo, is preparing a demonstrative experiment in collaboration with JMA, for a better utilization of Nowcast Earthquake Information to apply actual measures to reduce earthquake disasters caused by strong ground motion.

Widespread ground motion distribution caused by rupture directivity during the 2015 Gorkha, Nepal earthquake

NASA Astrophysics Data System (ADS)

Koketsu, Kazuki; Miyake, Hiroe; Guo, Yujia; Kobayashi, Hiroaki; Masuda, Tetsu; Davuluri, Srinagesh; Bhattarai, Mukunda; Adhikari, Lok Bijaya; Sapkota, Soma Nath

2016-06-01

The ground motion and damage caused by the 2015 Gorkha, Nepal earthquake can be characterized by their widespread distributions to the east. Evidence from strong ground motions, regional acceleration duration, and teleseismic waveforms indicate that rupture directivity contributed significantly to these distributions. This phenomenon has been thought to occur only if a strike-slip or dip-slip rupture propagates to a site in the along-strike or updip direction, respectively. However, even though the earthquake was a dip-slip faulting event and its source fault strike was nearly eastward, evidence for rupture directivity is found in the eastward direction. Here, we explore the reasons for this apparent inconsistency by performing a joint source inversion of seismic and geodetic datasets, and conducting ground motion simulations. The results indicate that the earthquake occurred on the underthrusting Indian lithosphere, with a low dip angle, and that the fault rupture propagated in the along-strike direction at a velocity just slightly below the S-wave velocity. This low dip angle and fast rupture velocity produced rupture directivity in the along-strike direction, which caused widespread ground motion distribution and significant damage extending far eastwards, from central Nepal to Mount Everest.

A Parametric Study of Nonlinear Seismic Response Analysis of Transmission Line Structures

PubMed Central

Wang, Yanming; Yi, Zhenhua

2014-01-01

A parametric study of nonlinear seismic response analysis of transmission line structures subjected to earthquake loading is studied in this paper. The transmission lines are modeled by cable element which accounts for the nonlinearity of the cable based on a real project. Nonuniform ground motions are generated using a stochastic approach based on random vibration analysis. The effects of multicomponent ground motions, correlations among multicomponent ground motions, wave travel, coherency loss, and local site on the responses of the cables are investigated using nonlinear time history analysis method, respectively. The results show the multicomponent seismic excitations should be considered, but the correlations among multicomponent ground motions could be neglected. The wave passage effect has a significant influence on the responses of the cables. The change of the degree of coherency loss has little influence on the response of the cables, but the responses of the cables are affected significantly by the effect of coherency loss. The responses of the cables change little with the degree of the difference of site condition changing. The effect of multicomponent ground motions, wave passage, coherency loss, and local site should be considered for the seismic design of the transmission line structures. PMID:25133215

Implications of the Mw9.0 Tohoku-Oki earthquake for ground motion scaling with source, path, and site parameters

USGS Publications Warehouse

Stewart, Jonathan P.; Midorikawa, Saburoh; Graves, Robert W.; Khodaverdi, Khatareh; Kishida, Tadahiro; Miura, Hiroyuki; Bozorgnia, Yousef; Campbell, Kenneth W.

2013-01-01

The Mw9.0 Tohoku-oki Japan earthquake produced approximately 2,000 ground motion recordings. We consider 1,238 three-component accelerograms corrected with component-specific low-cut filters. The recordings have rupture distances between 44 km and 1,000 km, time-averaged shear wave velocities of VS30 = 90 m/s to 1,900 m/s, and usable response spectral periods of 0.01 sec to >10 sec. The data support the notion that the increase of ground motions with magnitude saturates at large magnitudes. High-frequency ground motions demonstrate faster attenuation with distance in backarc than in forearc regions, which is only captured by one of the four considered ground motion prediction equations for subduction earthquakes. Recordings within 100 km of the fault are used to estimate event terms, which are generally positive (indicating model underprediction) at short periods and zero or negative (overprediction) at long periods. We find site amplification to scale minimally with VS30 at high frequencies, in contrast with other active tectonic regions, but to scale strongly with VS30 at low frequencies.

PEER NGA-East Overview: Development of a Ground Motion Characterization Model (Ground Motion Prediction Equations) for Central and Eastern North America

NASA Astrophysics Data System (ADS)

Goulet, C. A.; Abrahamson, N. A.; Al Atik, L.; Atkinson, G. M.; Bozorgnia, Y.; Graves, R. W.; Kuehn, N. M.; Youngs, R. R.

2017-12-01

The Next Generation Attenuation project for Central and Eastern North America (CENA), NGA-East, is a major multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER). The project was co-sponsored by the U.S. Nuclear Regulatory Commission (NRC), the U.S. Department of Energy (DOE), the Electric Power Research Institute (EPRI) and the U.S. Geological Survey (USGS). NGA-East involved a large number of participating researchers from various organizations in academia, industry and government and was carried-out as a combination of 1) a scientific research project and 2) a model-building component following the NRC Seismic Senior Hazard Analysis Committee (SSHAC) Level 3 process. The science part of the project led to several data products and technical reports while the SSHAC component aggregated the various results into a ground motion characterization (GMC) model. The GMC model consists in a set of ground motion models (GMMs) for median and standard deviation of ground motions and their associated weights, combined into logic-trees for use in probabilistic seismic hazard analyses (PSHA). NGA-East addressed many technical challenges, most of them related to the relatively small number of earthquake recordings available for CENA. To resolve this shortcoming, the project relied on ground motion simulations to supplement the available data. Other important scientific issues were addressed through research projects on topics such as the regionalization of seismic source, path and attenuation of motions, the treatment of variability and uncertainties and on the evaluation of site effects. Seven working groups were formed to cover the complexity and breadth of topics in the NGA-East project, each focused on a specific technical area. This presentation provides an overview of the NGA-East research project and its key products.

The effect of sinusoidal rolling ground motion on lifting biomechanics.

PubMed

Ning, Xiaopeng; Mirka, Gary A

2010-12-01

The objective of this study was to quantify the effects of ground surface motion on the biomechanical responses of a person performing a lifting task. A boat motion simulator (BMS) was built to provide a sinusoidal ground motion (simultaneous vertical linear translation and a roll angular displacement) that simulates the deck motion on a small fishing boat. Sixteen participants performed lifting, lowering and static holding tasks under conditions of two levels of mass (5 and 10 kg) and five ground moving conditions. Each ground moving condition was specified by its ground angular displacement and instantaneous vertical acceleration: A): +6°, -0.54 m/s(2); B): +3°, -0.27 m/s(2); C): 0°, 0m/s(2); D): -3°, 0.27 m/s(2); and E): -6°, 0.54 m/s(2). As they performed these tasks, trunk kinematics were captured using the lumbar motion monitor and trunk muscle activities were evaluated through surface electromyography. The results showed that peak sagittal plane angular acceleration was significantly higher in Condition A than in Conditions C, D and E (698°/s(2) vs. 612-617°/s(2)) while peak sagittal plane angular deceleration during lowering was significantly higher in moving conditions (conditions A and E) than in the stationary condition C (538-542°/s(2) vs. 487°/s(2)). The EMG results indicate that the boat motions tend to amplify the effects of the slant of the lifting surface and the external oblique musculature plays an important role in stabilizing the torso during these dynamic lifting tasks. Copyright © 2010 Elsevier Ltd. All rights reserved.

A Hybrid Ground-Motion Prediction Equation for Earthquakes in Western Alberta

NASA Astrophysics Data System (ADS)

Spriggs, N.; Yenier, E.; Law, A.; Moores, A. O.

2015-12-01

Estimation of ground-motion amplitudes that may be produced by future earthquakes constitutes the foundation of seismic hazard assessment and earthquake-resistant structural design. This is typically done by using a prediction equation that quantifies amplitudes as a function of key seismological variables such as magnitude, distance and site condition. In this study, we develop a hybrid empirical prediction equation for earthquakes in western Alberta, where evaluation of seismic hazard associated with induced seismicity is of particular interest. We use peak ground motions and response spectra from recorded seismic events to model the regional source and attenuation attributes. The available empirical data is limited in the magnitude range of engineering interest (M>4). Therefore, we combine empirical data with a simulation-based model in order to obtain seismologically informed predictions for moderate-to-large magnitude events. The methodology is two-fold. First, we investigate the shape of geometrical spreading in Alberta. We supplement the seismic data with ground motions obtained from mining/quarry blasts, in order to gain insights into the regional attenuation over a wide distance range. A comparison of ground-motion amplitudes for earthquakes and mining/quarry blasts show that both event types decay at similar rates with distance and demonstrate a significant Moho-bounce effect. In the second stage, we calibrate the source and attenuation parameters of a simulation-based prediction equation to match the available amplitude data from seismic events. We model the geometrical spreading using a trilinear function with attenuation rates obtained from the first stage, and calculate coefficients of anelastic attenuation and site amplification via regression analysis. This provides a hybrid ground-motion prediction equation that is calibrated for observed motions in western Alberta and is applicable to moderate-to-large magnitude events.

International Society for Terrain-Vehicle Systems European Conference (5th) Held in Budapest, Hungary on September 4-6, 1991: Proceedings, Volume 1

DTIC Science & Technology

1991-09-01

spatial rigid - body equations of motion . The predicted data was accurately correlated with the experimental data of scale model tests in the soil bin...models on hard level ground [1, 2] and on soft level ground [3]. For spatial motion on nonlevel ground a rigid - body mobility model was recently developed...Vehicles (1) Kinematics of the vehicle and coordinate systems A spatial motion of a tracked vehicle represented as a rigid body in a Euclidian 3-space

Seismic Data for Evaluation of Ground Motion Hazards in Las Vegas in Support of Test Site Readiness Ground Motion

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

Rodgers, A

2008-01-16

In this report we describe the data sets used to evaluate ground motion hazards in Las Vegas from nuclear tests at the Nevada Test Site. This analysis is presented in Rodgers et al. (2005, 2006) and includes 13 nuclear explosions recorded at the John Blume and Associates network, the Little Skull Mountain earthquake and a temporary deployment of broadband station in Las Vegas. The data are available in SAC format on CD-ROM as an appendix to this report.

Effects of motion speed in action representations

PubMed Central

van Dam, Wessel O.; Speed, Laura J.; Lai, Vicky T.; Vigliocco, Gabriella; Desai, Rutvik H.

2017-01-01

Grounded cognition accounts of semantic representation posit that brain regions traditionally linked to perception and action play a role in grounding the semantic content of words and sentences. Sensory-motor systems are thought to support partially abstract simulations through which conceptual content is grounded. However, which details of sensory-motor experience are included in, or excluded from these simulations, is not well understood. We investigated whether sensory-motor brain regions are differentially involved depending on the speed of actions described in a sentence. We addressed this issue by examining the neural signature of relatively fast (The old lady scurried across the road) and slow (The old lady strolled across the road) action sentences. The results showed that sentences that implied fast motion modulated activity within the right posterior superior temporal sulcus and the angular and middle occipital gyri, areas associated with biological motion and action perception. Sentences that implied slow motion resulted in greater signal within the right primary motor cortex and anterior inferior parietal lobule, areas associated with action execution and planning. These results suggest that the speed of described motion influences representational content and modulates the nature of conceptual grounding. Fast motion events are represented more visually whereas motor regions play a greater role in representing conceptual content associated with slow motion. PMID:28160739

Two terminal micropower radar sensor

DOEpatents

McEwan, Thomas E.

1995-01-01

A simple, low power ultra-wideband radar motion sensor/switch configuration connects a power source and load to ground. The switch is connected to and controlled by the signal output of a radar motion sensor. The power input of the motion sensor is connected to the load through a diode which conducts power to the motion sensor when the switch is open. A storage capacitor or rechargeable battery is connected to the power input of the motion sensor. The storage capacitor or battery is charged when the switch is open and powers the motion sensor when the switch is closed. The motion sensor and switch are connected between the same two terminals between the source/load and ground.

Two terminal micropower radar sensor

DOEpatents

McEwan, T.E.

1995-11-07

A simple, low power ultra-wideband radar motion sensor/switch configuration connects a power source and load to ground. The switch is connected to and controlled by the signal output of a radar motion sensor. The power input of the motion sensor is connected to the load through a diode which conducts power to the motion sensor when the switch is open. A storage capacitor or rechargeable battery is connected to the power input of the motion sensor. The storage capacitor or battery is charged when the switch is open and powers the motion sensor when the switch is closed. The motion sensor and switch are connected between the same two terminals between the source/load and ground. 3 figs.

Mechanisms of time-based figure-ground segregation.

PubMed

Kandil, Farid I; Fahle, Manfred

2003-11-01

Figure-ground segregation can rely on purely temporal information, that is, on short temporal delays between positional changes of elements in figure and ground (Kandil, F.I. & Fahle, M. (2001) Eur. J. Neurosci., 13, 2004-2008). Here, we investigate the underlying mechanisms by measuring temporal segregation thresholds for various kinds of motion cues. Segregation can rely on monocular first-order motion (based on luminance modulation) and second-order motion cues (contrast modulation) with a high temporal resolution of approximately 20 ms. The mechanism can also use isoluminant motion with a reduced temporal resolution of 60 ms. Figure-ground segregation can be achieved even at presentation frequencies too high for human subjects to inspect successive frames individually. In contrast, when stimuli are presented dichoptically, i.e. separately to both eyes, subjects are unable to perceive any segregation, irrespective of temporal frequency. We propose that segregation in these displays is detected by a mechanism consisting of at least two stages. On the first level, standard motion or flicker detectors signal local positional changes (flips). On the second level, a segregation mechanism combines the local activities of the low-level detectors with high temporal precision. Our findings suggest that the segregation mechanism can rely on monocular detectors but not on binocular mechanisms. Moreover, the results oppose the idea that segregation in these displays is achieved by motion detectors of a higher order (motion-from-motion), but favour mechanisms sensitive to short temporal delays even without activation of higher-order motion detectors.

Stochastic ground-motion simulations for the 2016 Kumamoto, Japan, earthquake

NASA Astrophysics Data System (ADS)

Zhang, Long; Chen, Guangqi; Wu, Yanqiang; Jiang, Han

2016-11-01

On April 15, 2016, Kumamoto, Japan, was struck by a large earthquake sequence, leading to severe casualty and building damage. The stochastic finite-fault method based on a dynamic corner frequency has been applied to perform ground-motion simulations for the 2016 Kumamoto earthquake. There are 53 high-quality KiK-net stations available in the Kyushu region, and we employed records from all stations to determine region-specific source, path and site parameters. The calculated S-wave attenuation for the Kyushu region beneath the volcanic and non-volcanic areas can be expressed in the form of Q s = (85.5 ± 1.5) f 0.68±0.01 and Q s = (120 ± 5) f 0.64±0.05, respectively. The effects of lateral S-wave velocity and attenuation heterogeneities on the ground-motion simulations were investigated. Site amplifications were estimated using the corrected cross-spectral ratios technique. Zero-distance kappa filter was obtained to be the value of 0.0514 ± 0.0055 s, using the spectral decay method. The stress drop of the mainshock based on the USGS slip model was estimated optimally to have a value of 64 bars. Our finite-fault model with optimized parameters was validated through the good agreement of observations and simulations at all stations. The attenuation characteristics of the simulated peak ground accelerations were also successfully captured by the ground-motion prediction equations. Finally, the ground motions at two destructively damaged regions, Kumamoto Castle and Minami Aso village, were simulated. We conclude that the stochastic finite-fault method with well-determined parameters can reproduce the ground-motion characteristics of the 2016 Kumamoto earthquake in both the time and frequency domains. This work is necessary for seismic hazard assessment and mitigation.[Figure not available: see fulltext.

Probabilistic Relationships between Ground‐Motion Parameters and Modified Mercalli Intensity in California

USGS Publications Warehouse

Worden, C.B.; Wald, David J.; Rhoades, D.A.

2012-01-01

We use a database of approximately 200,000 modified Mercalli intensity (MMI) observations of California earthquakes collected from USGS "Did You Feel It?" (DYFI) reports, along with a comparable number of peak ground-motion amplitudes from California seismic networks, to develop probabilistic relationships between MMI and peak ground velocity (PGV), peak ground acceleration (PGA), and 0.3-s, 1-s, and 3-s 5% damped pseudospectral acceleration (PSA). After associating each ground-motion observation with an MMI computed from all the DYFI responses within 2 km of the observation, we derived a joint probability distribution between MMI and ground motion. We then derived reversible relationships between MMI and each ground-motion parameter by using a total least squares regression to fit a bilinear function to the median of the stacked probability distributions. Among the relationships, the fit to peak ground velocity has the smallest errors, though linear combinations of PGA and PGV give nominally better results. We also find that magnitude and distance terms reduce the overall residuals and are justifiable on an information theoretic basis. For intensities MMI≥5, our results are in close agreement with the relations of Wald, Quitoriano, Heaton, and Kanamori (1999); for lower intensities, our results fall midway between Wald, Quitoriano, Heaton, and Kanamori (1999) and those of Atkinson and Kaka (2007). The earthquakes in the study ranged in magnitude from 3.0 to 7.3, and the distances ranged from less than a kilometer to about 400 km from the source.

Uncertainties in Earthquake Loss Analysis: A Case Study From Southern California

NASA Astrophysics Data System (ADS)

Mahdyiar, M.; Guin, J.

2005-12-01

Probabilistic earthquake hazard and loss analyses play important roles in many areas of risk management, including earthquake related public policy and insurance ratemaking. Rigorous loss estimation for portfolios of properties is difficult since there are various types of uncertainties in all aspects of modeling and analysis. It is the objective of this study to investigate the sensitivity of earthquake loss estimation to uncertainties in regional seismicity, earthquake source parameters, ground motions, and sites' spatial correlation on typical property portfolios in Southern California. Southern California is an attractive region for such a study because it has a large population concentration exposed to significant levels of seismic hazard. During the last decade, there have been several comprehensive studies of most regional faults and seismogenic sources. There have also been detailed studies on regional ground motion attenuations and regional and local site responses to ground motions. This information has been used by engineering seismologists to conduct regional seismic hazard and risk analysis on a routine basis. However, one of the more difficult tasks in such studies is the proper incorporation of uncertainties in the analysis. From the hazard side, there are uncertainties in the magnitudes, rates and mechanisms of the seismic sources and local site conditions and ground motion site amplifications. From the vulnerability side, there are considerable uncertainties in estimating the state of damage of buildings under different earthquake ground motions. From an analytical side, there are challenges in capturing the spatial correlation of ground motions and building damage, and integrating thousands of loss distribution curves with different degrees of correlation. In this paper we propose to address some of these issues by conducting loss analyses of a typical small portfolio in southern California, taking into consideration various source and ground motion uncertainties. The approach is designed to integrate loss distribution functions with different degrees of correlation for portfolio analysis. The analysis is based on USGS 2002 regional seismicity model.

Neurons Forming Optic Glomeruli Compute Figure–Ground Discriminations in Drosophila

PubMed Central

Aptekar, Jacob W.; Keleş, Mehmet F.; Lu, Patrick M.; Zolotova, Nadezhda M.

2015-01-01

Many animals rely on visual figure–ground discrimination to aid in navigation, and to draw attention to salient features like conspecifics or predators. Even figures that are similar in pattern and luminance to the visual surroundings can be distinguished by the optical disparity generated by their relative motion against the ground, and yet the neural mechanisms underlying these visual discriminations are not well understood. We show in flies that a diverse array of figure–ground stimuli containing a motion-defined edge elicit statistically similar behavioral responses to one another, and statistically distinct behavioral responses from ground motion alone. From studies in larger flies and other insect species, we hypothesized that the circuitry of the lobula—one of the four, primary neuropiles of the fly optic lobe—performs this visual discrimination. Using calcium imaging of input dendrites, we then show that information encoded in cells projecting from the lobula to discrete optic glomeruli in the central brain group these sets of figure–ground stimuli in a homologous manner to the behavior; “figure-like” stimuli are coded similar to one another and “ground-like” stimuli are encoded differently. One cell class responds to the leading edge of a figure and is suppressed by ground motion. Two other classes cluster any figure-like stimuli, including a figure moving opposite the ground, distinctly from ground alone. This evidence demonstrates that lobula outputs provide a diverse basis set encoding visual features necessary for figure detection. PMID:25972183

Neurons forming optic glomeruli compute figure-ground discriminations in Drosophila.

PubMed

Aptekar, Jacob W; Keleş, Mehmet F; Lu, Patrick M; Zolotova, Nadezhda M; Frye, Mark A

2015-05-13

Many animals rely on visual figure-ground discrimination to aid in navigation, and to draw attention to salient features like conspecifics or predators. Even figures that are similar in pattern and luminance to the visual surroundings can be distinguished by the optical disparity generated by their relative motion against the ground, and yet the neural mechanisms underlying these visual discriminations are not well understood. We show in flies that a diverse array of figure-ground stimuli containing a motion-defined edge elicit statistically similar behavioral responses to one another, and statistically distinct behavioral responses from ground motion alone. From studies in larger flies and other insect species, we hypothesized that the circuitry of the lobula--one of the four, primary neuropiles of the fly optic lobe--performs this visual discrimination. Using calcium imaging of input dendrites, we then show that information encoded in cells projecting from the lobula to discrete optic glomeruli in the central brain group these sets of figure-ground stimuli in a homologous manner to the behavior; "figure-like" stimuli are coded similar to one another and "ground-like" stimuli are encoded differently. One cell class responds to the leading edge of a figure and is suppressed by ground motion. Two other classes cluster any figure-like stimuli, including a figure moving opposite the ground, distinctly from ground alone. This evidence demonstrates that lobula outputs provide a diverse basis set encoding visual features necessary for figure detection. Copyright © 2015 the authors 0270-6474/15/357587-13$15.00/0.

Stochastic point-source modeling of ground motions in the Cascadia region

USGS Publications Warehouse

Atkinson, G.M.; Boore, D.M.

1997-01-01

A stochastic model is used to develop preliminary ground motion relations for the Cascadia region for rock sites. The model parameters are derived from empirical analyses of seismographic data from the Cascadia region. The model is based on a Brune point-source characterized by a stress parameter of 50 bars. The model predictions are compared to ground-motion data from the Cascadia region and to data from large earthquakes in other subduction zones. The point-source simulations match the observations from moderate events (M 100 km). The discrepancy at large magnitudes suggests further work on modeling finite-fault effects and regional attenuation is warranted. In the meantime, the preliminary equations are satisfactory for predicting motions from events of M < 7 and provide conservative estimates of motions from larger events at distances less than 100 km.

NGA-West2 Research Project

USGS Publications Warehouse

Bozorgnia, Yousef; Abrahamson, Norman A.; Al Atik, Linda; Ancheta, Timothy D.; Atkinson, Gail M.; Baker, Jack W.; Baltay, Annemarie S.; Boore, David M.; Campbell, Kenneth W.; Chiou, Brian S.J.; Darragh, Robert B.; Day, Steve; Donahue, Jennifer; Graves, Robert W.; Gregor, Nick; Hanks, Thomas C.; Idriss, I. M.; Kamai, Ronnie; Kishida, Tadahiro; Kottke, Albert; Mahin, Stephen A.; Rezaeian, Sanaz; Rowshandel, Badie; Seyhan, Emel; Shahi, Shrey; Shantz, Tom; Silva, Walter; Spudich, Paul A.; Stewart, Jonathan P.; Watson-Lamprey, Jennie; Wooddell, Kathryn; Youngs, Robert

2014-01-01

The NGA-West2 project is a large multidisciplinary, multi-year research program on the Next Generation Attenuation (NGA) models for shallow crustal earthquakes in active tectonic regions. The research project has been coordinated by the Pacific Earthquake Engineering Research Center (PEER), with extensive technical interactions among many individuals and organizations. NGA-West2 addresses several key issues in ground-motion seismic hazard, including updating the NGA database for a magnitude range of 3.0–7.9; updating NGA ground-motion prediction equations (GMPEs) for the “average” horizontal component; scaling response spectra for damping values other than 5%; quantifying the effects of directivity and directionality for horizontal ground motion; resolving discrepancies between the NGA and the National Earthquake Hazards Reduction Program (NEHRP) site amplification factors; analysis of epistemic uncertainty for NGA GMPEs; and developing GMPEs for vertical ground motion. This paper presents an overview of the NGA-West2 research program and its subprojects.

Response analysis of curved bridge with unseating failure control system under near-fault ground motions

NASA Astrophysics Data System (ADS)

Zuo, Ye; Sun, Guangjun; Li, Hongjing

2018-01-01

Under the action of near-fault ground motions, curved bridges are prone to pounding, local damage of bridge components and even unseating. A multi-scale fine finite element model of a typical three-span curved bridge is established by considering the elastic-plastic behavior of piers and pounding effect of adjacent girders. The nonlinear time-history method is used to study the seismic response of the curved bridge equipped with unseating failure control system under the action of near-fault ground motion. An in-depth analysis is carried to evaluate the control effect of the proposed unseating failure control system. The research results indicate that under the near-fault ground motion, the seismic response of the curved bridge is strong. The unseating failure control system perform effectively to reduce the pounding force of the adjacent girders and the probability of deck unseating.

Visualizing the ground motions of the 1906 San Francisco earthquake

USGS Publications Warehouse

Chourasia, A.; Cutchin, S.; Aagaard, Brad T.

2008-01-01

With advances in computational capabilities and refinement of seismic wave-propagation models in the past decade large three-dimensional simulations of earthquake ground motion have become possible. The resulting datasets from these simulations are multivariate, temporal and multi-terabyte in size. Past visual representations of results from seismic studies have been largely confined to static two-dimensional maps. New visual representations provide scientists with alternate ways of viewing and interacting with these results potentially leading to new and significant insight into the physical phenomena. Visualizations can also be used for pedagogic and general dissemination purposes. We present a workflow for visual representation of the data from a ground motion simulation of the great 1906 San Francisco earthquake. We have employed state of the art animation tools for visualization of the ground motions with a high degree of accuracy and visual realism. ?? 2008 Elsevier Ltd.

Analytical approach to calculation of response spectra from seismological models of ground motion

USGS Publications Warehouse

Safak, Erdal

1988-01-01

An analytical approach to calculate response spectra from seismological models of ground motion is presented. Seismological models have three major advantages over empirical models: (1) they help in an understanding of the physics of earthquake mechanisms, (2) they can be used to predict ground motions for future earthquakes and (3) they can be extrapolated to cases where there are no data available. As shown with this study, these models also present a convenient form for the calculation of response spectra, by using the methods of random vibration theory, for a given magnitude and site conditions. The first part of the paper reviews the past models for ground motion description, and introduces the available seismological models. Then, the random vibration equations for the spectral response are presented. The nonstationarity, spectral bandwidth and the correlation of the peaks are considered in the calculation of the peak response.

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%.

Comparisons of ground motions from five aftershocks of the 1999 Chi-Chi, Taiwan, earthquake with empirical predictions largely based on data from California

USGS Publications Warehouse

Wang, G.-Q.; Boore, D.M.; Igel, H.; Zhou, X.-Y.

2004-01-01

The observed ground motions from five large aftershocks of the 1999 Chi-Chi, Taiwan, earthquake are compared with predictions from four equations based primarily on data from California. The four equations for active tectonic regions are those developed by Abrahamson and Silva (1997), Boore et al. (1997), Campbell (1997, 2001), and Sadigh et al. (1997). Comparisons are made for horizontal-component peak ground accelerations and 5%-damped pseudoacceleration response spectra at periods between 0.02 sec and 5 sec. The observed motions are in reasonable agreement with the predictions, particularly for distances from 10 to 30 km. This is in marked contrast to the motions from the Chi-Chi mainshock, which are much lower than the predicted motions for periods less than about 1 sec. The results indicate that the low motions in the mainshock are not due to unusual, localized absorption of seismic energy, because waves from the mainshock and the aftershocks generally traverse the same section of the crust and are recorded at the same stations. The aftershock motions at distances of 30-60 km are somewhat lower than the predictions (but not nearly by as small a factor as those for the mainshock), suggesting that the ground motion attenuates more rapidly in this region of Taiwan than it does in the areas we compare with it. We provide equations for the regional attenuation of response spectra, which show increasing decay of motion with distance for decreasing oscillator periods. This observational study also demonstrates that ground motions have large earthquake-location-dependent variability for a specific site. This variability reduces the accuracy with which an earthquake-specific prediction of site response can be predicted. Online Material: PGAs and PSAs from the 1999 Chi-Chi earthquake and five aftershocks.

Gravitational Wave Astrophysics: Opening the New Frontier

NASA Technical Reports Server (NTRS)

Centrella, Joan

2011-01-01

The gravitational wave window onto the universe is expected to open in approximately 5 years, when ground-based detectors make the first detections in the high-frequency regime. Gravitational waves are ripples in spacetime produced by the motions of massive objects such as black holes and neutron stars. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources - such as masses, spins, luminosity distances, and orbital parameters through dense, obscured regions across cosmic time. This talk will explore gravitational waves as cosmic messengers, highlighting key sources, detection methods, and the astrophysical payoffs across the gravitational wave spectrum.

Earth science: lasting earthquake legacy

USGS Publications Warehouse

Parsons, Thomas E.

2009-01-01

On 31 August 1886, a magnitude-7 shock struck Charleston, South Carolina; low-level activity continues there today. One view of seismic hazard is that large earthquakes will return to New Madrid and Charleston at intervals of about 500 years. With expected ground motions that would be stronger than average, that prospect produces estimates of earthquake hazard that rival those at the plate boundaries marked by the San Andreas fault and Cascadia subduction zone. The result is two large 'bull's-eyes' on the US National Seismic Hazard Maps — which, for example, influence regional building codes and perceptions of public safety.

Gravitational Wave Astrophysics: Opening the New Frontier

NASA Technical Reports Server (NTRS)

Centrella, Joan

2011-01-01

The gravitational wave window onto the universe is expected to open in approx. 5 years, when ground-based detectors make the first detections in the high-frequency regime. Gravitational waves are ripples in spacetime produced by the motions of massive objects such as black holes and neutron stars. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources - such as masses, spins, luminosity distances, and orbital parameters, through dense, obscured regions across cosmic time. This article explores gravitational waves as cosmic messengers, highlighting key sources, detection methods, and the astrophysical payoffs across the gravitational wave spectrum.

Strong Motion Recording in the United States

NASA Astrophysics Data System (ADS)

Archuleta, R. J.; Fletcher, J. B.; Shakal, A. F.

2014-12-01

The United States strong motion program began in 1932 when the Coast and Geodetic Survey (C&GS) installed eight strong motion accelerographs in California. During the March 1933 Long Beach earthquake, three of these produced the first strong motion records. With this success the C&GS expanded the number of accelerographs to 71 by 1964. With development of less expensive, mass-produced accelerographs the number of strong motion accelerographs expanded to ~575 by 1972. Responsibilities for operating the network and disseminating data were transferred to the National Oceanic and Atmospheric Administration in 1970 and then to the U.S. Geological Survey in 1973. In 1972 the California Legislature established the California Strong Motion Instrumentation Program (CSMIP). CSMIP operates accelerographs at 812 ground stations, with multi-channel accelerographs in 228 buildings, 125 lifelines and 37 geotechnical arrays, in California. The USGS and the ANSS effort operate accelerographs at 1584 ground stations, 96 buildings, 14 bridges, 70 dams, and 15 multi-channel geotechnical arrays. The USC Los Angeles array has 78 ground stations; UCSB operates 5 geotechnical arrays; other government and private institutions also operate accelerographs. Almost all accelerographs are now digital with a sampling rate of 200 Hz. Most of the strong motion data can be downloaded from the Center for Engineering Strong Motion Data (http://strongmotioncenter.org). As accelerographs have become more sophisticated, the concept of what constitutes strong motion has blurred because small earthquakes (M ~3) are well recorded on accelerometers as well as seismometers. However, when accelerations are over ~10%g and velocities over ~1 cm/s, the accelerometers remain on scale, providing the unclipped data necessary to analyze the ground motion and its consequences. Strong motion data are essential to the development of ground motion prediction equations, understanding structural response, performance based engineering, soil response, and inversions for earthquake rupture parameters. While an important number of stations have been installed, many areas of the US are significantly deficient, e.g., recordings were obtained from only 2 stations within 60 km of the Mineral earthquake that damaged the nation's capital and other areas.

Physics-Based Hazard Assessment for Critical Structures Near Large Earthquake Sources

NASA Astrophysics Data System (ADS)

Hutchings, L.; Mert, A.; Fahjan, Y.; Novikova, T.; Golara, A.; Miah, M.; Fergany, E.; Foxall, W.

2017-09-01

We argue that for critical structures near large earthquake sources: (1) the ergodic assumption, recent history, and simplified descriptions of the hazard are not appropriate to rely on for earthquake ground motion prediction and can lead to a mis-estimation of the hazard and risk to structures; (2) a physics-based approach can address these issues; (3) a physics-based source model must be provided to generate realistic phasing effects from finite rupture and model near-source ground motion correctly; (4) wave propagations and site response should be site specific; (5) a much wider search of possible sources of ground motion can be achieved computationally with a physics-based approach; (6) unless one utilizes a physics-based approach, the hazard and risk to structures has unknown uncertainties; (7) uncertainties can be reduced with a physics-based approach, but not with an ergodic approach; (8) computational power and computer codes have advanced to the point that risk to structures can be calculated directly from source and site-specific ground motions. Spanning the variability of potential ground motion in a predictive situation is especially difficult for near-source areas, but that is the distance at which the hazard is the greatest. The basis of a "physical-based" approach is ground-motion syntheses derived from physics and an understanding of the earthquake process. This is an overview paper and results from previous studies are used to make the case for these conclusions. Our premise is that 50 years of strong motion records is insufficient to capture all possible ranges of site and propagation path conditions, rupture processes, and spatial geometric relationships between source and site. Predicting future earthquake scenarios is necessary; models that have little or no physical basis but have been tested and adjusted to fit available observations can only "predict" what happened in the past, which should be considered description as opposed to prediction. We have developed a methodology for synthesizing physics-based broadband ground motion that incorporates the effects of realistic earthquake rupture along specific faults and the actual geology between the source and site.

An operational-oriented approach to the assessment of low probability seismic ground motions for critical infrastructures

NASA Astrophysics Data System (ADS)

Garcia-Fernandez, Mariano; Assatourians, Karen; Jimenez, Maria-Jose

2018-01-01

Extreme natural hazard events have the potential to cause significant disruption to critical infrastructure (CI) networks. Among them, earthquakes represent a major threat as sudden-onset events with limited, if any, capability of forecast, and high damage potential. In recent years, the increased exposure of interdependent systems has heightened concern, motivating the need for a framework for the management of these increased hazards. The seismic performance level and resilience of existing non-nuclear CIs can be analyzed by identifying the ground motion input values leading to failure of selected key elements. Main interest focuses on the ground motions exceeding the original design values, which should correspond to low probability occurrence. A seismic hazard methodology has been specifically developed to consider low-probability ground motions affecting elongated CI networks. The approach is based on Monte Carlo simulation, which allows for building long-duration synthetic earthquake catalogs to derive low-probability amplitudes. This approach does not affect the mean hazard values and allows obtaining a representation of maximum amplitudes that follow a general extreme-value distribution. This facilitates the analysis of the occurrence of extremes, i.e., very low probability of exceedance from unlikely combinations, for the development of, e.g., stress tests, among other applications. Following this methodology, extreme ground-motion scenarios have been developed for selected combinations of modeling inputs including seismic activity models (source model and magnitude-recurrence relationship), ground motion prediction equations (GMPE), hazard levels, and fractiles of extreme ground motion. The different results provide an overview of the effects of different hazard modeling inputs on the generated extreme motion hazard scenarios. This approach to seismic hazard is at the core of the risk analysis procedure developed and applied to European CI transport networks within the framework of the European-funded INFRARISK project. Such an operational seismic hazard framework can be used to provide insight in a timely manner to make informed risk management or regulating further decisions on the required level of detail or on the adoption of measures, the cost of which can be balanced against the benefits of the measures in question.

Stress accumulation in the Marmara Sea estimated through ground-motion simulations from dynamic rupture scenarios

NASA Astrophysics Data System (ADS)

Aochi, Hideo; Douglas, John; Ulrich, Thomas

2017-03-01

We compare ground motions simulated from dynamic rupture scenarios, for the seismic gap along the North Anatolian Fault under the Marmara Sea (Turkey), to estimates from empirical ground motion prediction equations (GMPEs). Ground motions are simulated using a finite difference method and a 3-D model of the local crustal structure. They are analyzed at more than a thousand locations in terms of horizontal peak ground velocity. Characteristics of probable earthquake scenarios are strongly dependent on the hypothesized level of accumulated stress, in terms of a normalized stress parameter T. With respect to the GMPEs, it is found that simulations for many scenarios systematically overestimate the ground motions at all distances. Simulations for only some scenarios, corresponding to moderate stress accumulation, match the estimates from the GMPEs. The difference between the simulations and the GMPEs is used to quantify the relative probabilities of each scenario and, therefore, to revise the probability of the stress field. A magnitude Mw7+ operating at moderate prestress field (0.6 < T ≤ 0.7) is statistically more probable, as previously assumed in the logic tree of probabilistic assessment of rupture scenarios. This approach of revising the mechanical hypothesis by means of comparison to an empirical statistical model (e.g., a GMPE) is useful not only for practical seismic hazard assessments but also to understand crustal dynamics.

Strong-motion data from the two Pingtung, Taiwan, earthquakes of 26 December 2006

USGS Publications Warehouse

Wu, C.-F.; Lee, W.H.K.; Boore, D.M.

2008-01-01

1016 strong-motion records at 527 free-field stations and 131 records at 42 strong-motion arrays at buildings and bridges were obtained for the Pingtung earthquake doublet from the Taiwan Central Weather Bureau's dense, digital strong-motion network. We carried out standard processing of these strong-motion records at free-field stations. A data set, including the originally recorded files, processed data files, and supporting software and information, is archived online http:// tecdc.earth.sinica.edu.tw/data/EQ2006Pingtung/. We have not yet completed the processing of the strong-motion array data at buildings and bridges. However, some preliminary results and the strong-motion array data recorded at the second nearest instrumented building to the Pingtung earthquake doublet are shown. This paper is intended to document our data processing procedures and the online archived data files, so that researchers can efficiently use the data. We also include two preliminary analyses: (1) a comparison of ground motions recorded by multiple accelerographs at a common site, the TAP 117 station in Taipei, and (2) attenuation of the horizontal ground motions (peak acceleration and response spectra at periods of 0.2, 1.0, and 3.0 s) with respect to distance. Our comparison study of multiple recordings at TAP 117 indicates that waveform coherence among 20- and 24-bit accelerograph records is much higher as compared to records from 16-bit or 12-bit accelerographs, suggesting that the former are of better quality. For the 20- and 24-bit accelerographs, waveform coherence is nearly 1 over the frequency range 1 to 8 Hz for all components, and is greater than about 0.9 from 8 to 20 Hz for the horizontal component, but only from 8 to 12 Hz for the vertical component. Plots of pseudo-acceleration response spectra (PSA) as a function of distance, however, show no clear indication for a difference related to the performance level of the accelerographs. The ground-motions of the first event (Mw = 7.0) are comparable, or even somewhat lower, than those from the smaller second event (Mw = 6.9), consistent with the relative difference of the local magnitudes (ML = 6.96 and 6.99 for the first and second events, respectively). The ground motions from the first event are generally lower than those predicted from equations based on other in-slab subduction earthquakes, whereas the ground motions from the second event are closer to the predictions. Ground-motions for soil sites are generally larger than those from rock sites.

Significance of rotating ground motions on nonlinear behavior of symmetric and asymmetric buildings in near fault sites

USGS Publications Warehouse

Kalkan, Erol; ,

2012-01-01

Building codes in the U.S. require at least two horizontal ground motion components for three-dimensional (3D) response history analysis (RHA) of structures. For sites within 5 km of an active fault, these records should be rotated to fault-normal/fault-parallel (FN/FP) directions, and two RHA analyses should be performed separately (when FN and then FP are aligned with transverse direction of the structural axes). It is assumed that this approach will lead to two sets of responses that envelope the range of possible responses over all non-redundant rotation angles. This assumption is examined here using 3D computer models of a single-story structure having symmetric (that is, torsionally-stiff) and asymmetric (that is, torsionally flexible) layouts subjected to an ensemble of bi-directional near-fault strong ground motions with and without apparent velocity pulses. In this parametric study, the elastic vibration period of the structures is varied from 0.2 to 5 seconds, and yield strength reduction factors R is varied from a value that leads to linear-elastic design to 3 and 5. The influence that the rotation angle of the ground motion has on several engineering demand parameters (EDPs) is examined in linear-elastic and nonlinear-inelastic domains to form a benchmark for evaluating the use of the FN/FP directions as well as the maximum-direction (MD) ground motion, a new definition of horizontal ground motions for use in the seismic design of structures according to the 2009 NEHRP Provisions and Commentary.

Strong ground motion of the 2016 Kumamoto earthquake

NASA Astrophysics Data System (ADS)

Aoi, S.; Kunugi, T.; Suzuki, W.; Kubo, H.; Morikawa, N.; Fujiwara, H.

2016-12-01

The 2016 Kumamoto earthquake that is composed of Mw 6.1 and Mw 7.1 earthquakes respectively occurred in the Kumamoto region at 21:26 on April 14 and 28 hours later at 1:25 on April 16, 2016 (JST). These earthquakes are considered to rupture mainly the Hinagu fault zone for the Mw 6.1 event and the Futagawa fault zone for the Mw 7.1 event, respectively, where the Headquarter for Earthquake Research Promotion performed the long-term evaluation as well as seismic hazard assessment prior to the 2016 Kumamoto earthquake. Strong shakings with seismic intensity 7 in the JMA scale were observed at four times in total: Mashiki town for the Mw 6.1 and Mw 7.1 events, Nishihara village for the Mw 7.1 event, and NIED/KiK-net Mashiki (KMMH16) for the Mw 7.1 event. KiK-net Mashiki (KMMH16) recorded peak ground acceleration more than 1000 cm/s/s, and Nishihara village recorded peak ground velocity more than 250 cm/s. Ground motions were observed wider area for the Mw 7.1 event than the Mw 6.1 event. Peak ground accelerations and peak ground velocities of K-NET/KiK-net stations are consistent with the ground motion prediction equations by Si and Midorikawa (1999). Peak ground velocities at longer distance than 200 km attenuate slowly, which can be attributed to the large Love wave with a dominant period around 10 seconds. 5%-damped pseudo spectral velocity of the Mashiki town shows a peak at period of 1-2 s that exceeds ground motion response of JR Takatori of the 1995 Kobe earthquake and the Kawaguchi town of the 2004 Chuetsu earthquake. 5%-damped pseudo spectral velocity of the Nishihara village shows 350 cm/s peak at period of 3-4 s that is similar to the several stations in Kathmandu basin by Takai et al. (2016) during the 2015 Gorkha earthquake in Nepal. Ground motions at several stations in Oita exceed the ground motion prediction equations due to an earthquake induced by the Mw 7.1 event. Peak ground accelerations of K-NET Yufuin (OIT009) records 90 cm/s/s for the Mw 7.1 event and 723 cm/s/s for the near-by induced event.

Analysis of ground-motion simulation big data

NASA Astrophysics Data System (ADS)

Maeda, T.; Fujiwara, H.

2016-12-01

We developed a parallel distributed processing system which applies a big data analysis to the large-scale ground motion simulation data. The system uses ground-motion index values and earthquake scenario parameters as input. We used peak ground velocity value and velocity response spectra as the ground-motion index. The ground-motion index values are calculated from our simulation data. We used simulated long-period ground motion waveforms at about 80,000 meshes calculated by a three dimensional finite difference method based on 369 earthquake scenarios of a great earthquake in the Nankai Trough. These scenarios were constructed by considering the uncertainty of source model parameters such as source area, rupture starting point, asperity location, rupture velocity, fmax and slip function. We used these parameters as the earthquake scenario parameter. The system firstly carries out the clustering of the earthquake scenario in each mesh by the k-means method. The number of clusters is determined in advance using a hierarchical clustering by the Ward's method. The scenario clustering results are converted to the 1-D feature vector. The dimension of the feature vector is the number of scenario combination. If two scenarios belong to the same cluster the component of the feature vector is 1, and otherwise the component is 0. The feature vector shows a `response' of mesh to the assumed earthquake scenario group. Next, the system performs the clustering of the mesh by k-means method using the feature vector of each mesh previously obtained. Here the number of clusters is arbitrarily given. The clustering of scenarios and meshes are performed by parallel distributed processing with Hadoop and Spark, respectively. In this study, we divided the meshes into 20 clusters. The meshes in each cluster are geometrically concentrated. Thus this system can extract regions, in which the meshes have similar `response', as clusters. For each cluster, it is possible to determine particular scenario parameters which characterize the cluster. In other word, by utilizing this system, we can obtain critical scenario parameters of the ground-motion simulation for each evaluation point objectively. This research was supported by CREST, JST.

Quantifying and Qualifying USGS ShakeMap Uncertainty

USGS Publications Warehouse

Wald, David J.; Lin, Kuo-Wan; Quitoriano, Vincent

2008-01-01

We describe algorithms for quantifying and qualifying uncertainties associated with USGS ShakeMap ground motions. The uncertainty values computed consist of latitude/longitude grid-based multiplicative factors that scale the standard deviation associated with the ground motion prediction equation (GMPE) used within the ShakeMap algorithm for estimating ground motions. The resulting grid-based 'uncertainty map' is essential for evaluation of losses derived using ShakeMaps as the hazard input. For ShakeMap, ground motion uncertainty at any point is dominated by two main factors: (i) the influence of any proximal ground motion observations, and (ii) the uncertainty of estimating ground motions from the GMPE, most notably, elevated uncertainty due to initial, unconstrained source rupture geometry. The uncertainty is highest for larger magnitude earthquakes when source finiteness is not yet constrained and, hence, the distance to rupture is also uncertain. In addition to a spatially-dependant, quantitative assessment, many users may prefer a simple, qualitative grading for the entire ShakeMap. We developed a grading scale that allows one to quickly gauge the appropriate level of confidence when using rapidly produced ShakeMaps as part of the post-earthquake decision-making process or for qualitative assessments of archived or historical earthquake ShakeMaps. We describe an uncertainty letter grading ('A' through 'F', for high to poor quality, respectively) based on the uncertainty map. A middle-range ('C') grade corresponds to a ShakeMap for a moderate-magnitude earthquake suitably represented with a point-source location. Lower grades 'D' and 'F' are assigned for larger events (M>6) where finite-source dimensions are not yet constrained. The addition of ground motion observations (or observed macroseismic intensities) reduces uncertainties over data-constrained portions of the map. Higher grades ('A' and 'B') correspond to ShakeMaps with constrained fault dimensions and numerous stations, depending on the density of station/data coverage. Due to these dependencies, the letter grade can change with subsequent ShakeMap revisions if more data are added or when finite-faulting dimensions are added. We emphasize that the greatest uncertainties are associated with unconstrained source dimensions for large earthquakes where the distance term in the GMPE is most uncertain; this uncertainty thus scales with magnitude (and consequently rupture dimension). Since this distance uncertainty produces potentially large uncertainties in ShakeMap ground-motion estimates, this factor dominates over compensating constraints for all but the most dense station distributions.

Characterizing directional variations in long-period ground motion amplifications in the Kanto Basin, Japan

NASA Astrophysics Data System (ADS)

Mukai, Y.; Furumura, T.; Maeda, T.

2017-12-01

In the Kanto Basin (including Tokyo in Japan), the long-period (T=3-10 s) ground motions are strongly developed when large earthquakes occur nearby. The amplitude of the long-period ground motion in the basin varies strongly among earthquakes; it is tremendous from the earthquakes in Niigata (northwest of Kanto), but is several times weaker from the earthquakes in Tohoku (north of Kanto). In this study, we examined the cause of such azimuthal-dependent amplitude variation for the 2004 Niigata Chuetsu (M6.8) and the 2011 Fukushima Hamadori (M7.0) earthquake based on numerical simulations of seismic wave propagation by the finite-difference method. We first examined the non-isotropic source-radiation effect of these events. By performing numerical simulations for different strike angles of these source faults, significant variation in amplitude of the long-period ground motions were observed in Tokyo for both the events. Among tested strike angles, the source of the 2004 event (strike = 212 deg.) produced the largest long-period ground motion due to strong radiation of surface wave towards the Kanto Basin, while the 2011 event (strike = 132 deg.) produced the least. The minimum-to-maximum ratio of their amplitudes with respect to strike angle is about 2 and 1.3, respectively. These investigations suggest the source radiation effect considerably contributes to the variations of the long-period ground motions. We then examined the effect of the 3D structure of the Kanto Basin on the generation of the long-period ground motion. For the 2004 event, we found that the long-period signal first arrives at the central Tokyo from the western edge of the Kanto Basin. Then, later signals containing both the Rayleigh and Love waves were amplified dramatically due to the localized low-velocity structure to the northwestern part of the basin. On the other hand, in the case of the 2011 event, the seismic waves propagating towards the basin were dissipated significantly as it travels over the ridge structure of the basement in the northern part of the basin, where the seismic wave speed is faster than the surroundings. Therefore, the large variation of the long-period ground motion among earthquakes occurs due to the combined effects of source radiation and propagation properties in the 3D heterogeneous structure of the Kanto Basin.

Required number of records for ASCE/SEI 7 ground-motion scaling procedure

USGS Publications Warehouse

Reyes, Juan C.; Kalkan, Erol

2011-01-01

The procedures and criteria in 2006 IBC (International Council of Building Officials, 2006) and 2007 CBC (International Council of Building Officials, 2007) for the selection and scaling ground-motions for use in nonlinear response history analysis (RHA) of structures are based on ASCE/SEI 7 provisions (ASCE, 2005, 2010). According to ASCE/SEI 7, earthquake records should be selected from events of magnitudes, fault distance, and source mechanisms that comply with the maximum considered earthquake, and then scaled so that the average value of the 5-percent-damped response spectra for the set of scaled records is not less than the design response spectrum over the period range from 0.2Tn to 1.5Tn sec (where Tn is the fundamental vibration period of the structure). If at least seven ground-motions are analyzed, the design values of engineering demand parameters (EDPs) are taken as the average of the EDPs determined from the analyses. If fewer than seven ground-motions are analyzed, the design values of EDPs are taken as the maximum values of the EDPs. ASCE/SEI 7 requires a minimum of three ground-motions. These limits on the number of records in the ASCE/SEI 7 procedure are based on engineering experience, rather than on a comprehensive evaluation. This study statistically examines the required number of records for the ASCE/SEI 7 procedure, such that the scaled records provide accurate, efficient, and consistent estimates of" true" structural responses. Based on elastic-perfectly-plastic and bilinear single-degree-of-freedom systems, the ASCE/SEI 7 scaling procedure is applied to 480 sets of ground-motions. The number of records in these sets varies from three to ten. The records in each set were selected either (i) randomly, (ii) considering their spectral shapes, or (iii) considering their spectral shapes and design spectral-acceleration value, A(Tn). As compared to benchmark (that is, "true") responses from unscaled records using a larger catalog of ground-motions, it is demonstrated that the ASCE/SEI 7 scaling procedure is overly conservative if fewer than seven ground-motions are employed. Utilizing seven or more randomly selected records provides a more accurate estimate of the EDPs accompanied by reduced record-to-record variability of the responses. Consistency in accuracy and efficiency is achieved only if records are selected on the basis of their spectral shape and A(Tn).

Convexities move because they contain matter.

PubMed

Barenholtz, Elan

2010-09-22

Figure-ground assignment to a contour is a fundamental stage in visual processing. The current paper introduces a novel, highly general dynamic cue to figure-ground assignment: "Convex Motion." Across six experiments, subjects showed a strong preference to assign figure and ground to a dynamically deforming contour such that the moving contour segment was convex rather than concave. Experiments 1 and 2 established the preference across two different kinds of deformational motion. Additional experiments determined that this preference was not due to fixation (Experiment 3) or attentional mechanisms (Experiment 4). Experiment 5 found a similar, but reduced bias for rigid-as opposed to deformational-motion, and Experiment 6 demonstrated that the phenomenon depends on the global motion of the effected contour. An explanation of this phenomenon is presented on the basis of typical natural deformational motion, which tends to involve convex contour projections that contain regions consisting of physical "matter," as opposed to concave contour indentations that contain empty space. These results highlight the fundamental relationship between figure and ground, perceived shape, and the inferred physical properties of an object.

Effects of deep basins on structural collapse during large subduction earthquakes

USGS Publications Warehouse

Marafi, Nasser A.; Eberhard, Marc O.; Berman, Jeffrey W.; Wirth, Erin A.; Frankel, Arthur

2017-01-01

Deep sedimentary basins are known to increase the intensity of ground motions, but this effect is implicitly considered in seismic hazard maps used in U.S. building codes. The basin amplification of ground motions from subduction earthquakes is particularly important in the Pacific Northwest, where the hazard at long periods is dominated by such earthquakes. This paper evaluates the effects of basins on spectral accelerations, ground-motion duration, spectral shape, and structural collapse using subduction earthquake recordings from basins in Japan that have similar depths as the Puget Lowland basin. For three of the Japanese basins and the Puget Lowland basin, the spectral accelerations were amplified by a factor of 2 to 4 for periods above 2.0 s. The long-duration subduction earthquakes and the effects of basins on spectral shape combined, lower the spectral accelerations at collapse for a set of building archetypes relative to other ground motions. For the hypothetical case in which these motions represent the entire hazard, the archetypes would need to increase up to 3.3 times its strength to compensate for these effects.

Postures and Motions Library Development for Verification of Ground Crew Human Systems Integration Requirements

NASA Technical Reports Server (NTRS)

Jackson, Mariea Dunn; Dischinger, Charles; Stambolian, Damon; Henderson, Gena

2012-01-01

Spacecraft and launch vehicle ground processing activities require a variety of unique human activities. These activities are being documented in a Primitive motion capture library. The Library will be used by the human factors engineering in the future to infuse real to life human activities into the CAD models to verify ground systems human factors requirements. As the Primitive models are being developed for the library the project has selected several current human factors issues to be addressed for the SLS and Orion launch systems. This paper explains how the Motion Capture of unique ground systems activities are being used to verify the human factors analysis requirements for ground system used to process the STS and Orion vehicles, and how the primitive models will be applied to future spacecraft and launch vehicle processing.

Postures and Motions Library Development for Verification of Ground Crew Human Factors Requirements

NASA Technical Reports Server (NTRS)

Stambolian, Damon; Henderson, Gena; Jackson, Mariea Dunn; Dischinger, Charles

2013-01-01

Spacecraft and launch vehicle ground processing activities require a variety of unique human activities. These activities are being documented in a primitive motion capture library. The library will be used by human factors engineering analysts to infuse real to life human activities into the CAD models to verify ground systems human factors requirements. As the primitive models are being developed for the library, the project has selected several current human factors issues to be addressed for the Space Launch System (SLS) and Orion launch systems. This paper explains how the motion capture of unique ground systems activities is being used to verify the human factors engineering requirements for ground systems used to process the SLS and Orion vehicles, and how the primitive models will be applied to future spacecraft and launch vehicle processing.

On the Relationship between Fourier and Response Spectra: Implications for the Adjustment of Empirical Ground-Motion Prediction Equations (GMPEs)

NASA Astrophysics Data System (ADS)

Bora, Sanjay; Scherbaum, Frank; Kuehn, Nicolas; Stafford, Peter

2016-04-01

Often, scaling of response spectral amplitudes, (e.g., spectral acceleration) obtained from empirical ground motion prediction equations (GMPEs), with respect to commonly used seismological parameters such as magnitude, distance and site condition is assumed/referred to be representing a similar scaling of Fourier spectral amplitudes. For instance, the distance scaling of response spectral amplitudes is related with the geometrical spreading of seismic waves. Such comparison of scaling of response spectral amplitudes with that of corresponding Fourier spectral amplitudes is motivated by that, the functional forms of response spectral GMPEs are often derived using the concepts borrowed from Fourier spectral modeling of ground motion. As these GMPEs are subsequently calibrated with empirical observations, this may not appear to pose any major problems in the prediction of ground motion for a particular earthquake scenario. However, the assumption that the Fourier spectral concepts persist for response spectra can lead to undesirable consequences when it comes to the adjustment of response spectral GMPEs to represent conditions not covered in the original empirical data set. In this context, a couple of important questions arise, e.g., what are the distinctions and/or similarities between Fourier and response spectra of ground-motions? And, if they are different, then what is the mechanism responsible for such differences and how do adjustments that are made to FAS manifest in response spectra? We explore the relationship between the Fourier and response spectrum of ground motion by using random vibration theory (RVT). With a simple Brune (1970, 1971) source model, RVT-generated acceleration spectra for a fixed magnitude and distance scenario are used. The RVT analyses reveal that the scaling of low oscillator-frequency response spectral ordinates can be treated as being equivalent to the scaling of the corresponding Fourier spectral ordinates. However, the high oscillator-frequency response spectral ordinates are controlled by a rather wide-band of Fourier spectral ordinates. In fact, the peak ground acceleration (PGA), counter to the popular perception that it is a reflection of the high-frequency characteristics of ground motion, is controlled by the entire Fourier spectrum of ground-motion. Finally, it is demonstrated, how an adjustment made in Fourier spectral amplitudes is different or similar to the same adjustment made in the response spectral amplitudes. For this purpose, two cases: adjustments to the stress parameter (Δσ) (source term) and to attributes reflecting site response (V s-κ0) are considered.

Displaced rocks, strong motion, and the mechanics of shallow faulting associated with the 1999 Hector Mine, California, earthquake

USGS Publications Warehouse

Michael, Andrew J.; Ross, Stephanie L.; Stenner, Heidi D.

2002-01-01

The paucity of strong-motion stations near the 1999 Hector Mine earthquake makes it impossible to make instrumental studies of key questions about near-fault strong-motion patterns associated with this event. However, observations of displaced rocks allow a qualitative investigation of these problems. By observing the slope of the desert surface and the frictional coefficient between these rocks and the desert surface, we estimate the minimum horizontal acceleration needed to displace the rocks. Combining this information with observations of how many rocks were displaced in different areas near the fault, we infer the level of shaking. Given current empirical shaking attenuation relationships, the number of rocks that moved is slightly lower than expected; this implies that slightly lower than expected shaking occurred during the Hector Mine earthquake. Perhaps more importantly, stretches of the fault with 4 m of total displacement at the surface displaced few nearby rocks on 15?? slopes, suggesting that the horizontal accelerations were below 0.2g within meters of the fault scarp. This low level of shaking suggests that the shallow parts of this rupture did not produce strong accelerations. Finally, we did not observe an increased incidence of displaced rocks along the fault zone itself. This suggests that, despite observations of fault-zone-trapped waves generated by aftershocks of the Hector Mine earthquake, such waves were not an important factor in controlling peak ground acceleration during the mainshock.

Adjusting central and eastern North America ground-motion intensity measures between sites with different reference-rock site conditions

USGS Publications Warehouse

Boore, David; Campbell, Kenneth W.

2017-01-01

Adjustment factors are provided for converting ground‐motion intensity measures between central and eastern North America (CENA) sites with different reference‐rock site conditions (VS30=760, 2000, and 3000  m/s) for moment magnitudes ranging from 2 to 8, rupture distances ranging from 2 to 1200 km, Fourier amplitude spectra (FAS) for frequencies ranging from 0.01 to 100 Hz, response spectra for periods ranging from 0.01 to 10.0 s, peak ground acceleration, and peak ground velocity. The adjustment factors are given for a wide range of the site diminution parameters (κ0) for sites with VS30=760  m/s and for a κ0 of 0.006 s for two harder rock sites. Fourteen CENA velocity profiles with VS30 values within a factor of 1.1 of 760  m/s were used to derive average FAS amplification factors as a function of frequency, which were then used in simulations of peak ground‐motion parameters and response spectra to derive the adjustment factors. The amplification function differs from that used in western North America (e.g., Campbell and Boore, 2016) in having a peak near 9 Hz, due to the resonance of motions in the relatively thin low‐velocity material over hard rock that characterizes many CENA sites with VS30 near 760  m/s. We call these B/C sites, because this velocity marks the boundary between National Earthquake Hazards Reduction Program site classes B and C (Building Seismic Safety Council, 2004). The adjustments for short‐period motions are sensitive to the value of κ0, but there are very few if any determinations of κ0 for CENA B/C sites. For this reason, we determined κ0from multiple recordings at Pinyon Flat Observatory (PFO), California, which has a velocity‐depth profile similar to those of CENA B/C sites. The PFO and other results from the literature suggest that appropriate values of κ0 for CENA B/C sites are expected to lie between 0.01 and 0.03 s.

Practical recommendations for evaluation and mitigation of soil liquefaction in Arkansas.

DOT National Transportation Integrated Search

2010-02-01

Northeastern Arkansas has some of the largest design earthquake ground motions : in the continental U.S. due to its location within the New Madrid Seismic Zone (NMSZ). : These large earthquake ground motions are particularly problematic when coupled ...

Human Factors Vehicle Displacement Analysis: Engineering In Motion

NASA Technical Reports Server (NTRS)

Atencio, Laura Ashley; Reynolds, David; Robertson, Clay

2010-01-01

While positioned on the launch pad at the Kennedy Space Center, tall stacked launch vehicles are exposed to the natural environment. Varying directional winds and vortex shedding causes the vehicle to sway in an oscillating motion. The Human Factors team recognizes that vehicle sway may hinder ground crew operation, impact the ground system designs, and ultimately affect launch availability . The objective of this study is to physically simulate predicted oscillation envelopes identified by analysis. and conduct a Human Factors Analysis to assess the ability to carry out essential Upper Stage (US) ground operator tasks based on predicted vehicle motion.

On the Analysis of Wind-Induced Noise in Seismological Recordings

NASA Astrophysics Data System (ADS)

Lott, Friederike F.; Ritter, Joachim R. R.; Al-Qaryouti, Mahmoud; Corsmeier, Ulrich

2017-03-01

Atmospheric processes, ranging from microscale turbulence to severe storms on the synoptic scale, impact the continuous ground motion of the earth and have the potential to induce strong broad-band noise in seismological recordings. We designed a target-oriented experiment to quantify the influence of wind on ground motion velocity in the Dead Sea valley. For the period from March 2014 to February 2015, a seismological array, consisting of 15 three-component short-period and broad-band stations, was operated near Madaba, Jordan, complemented by one meteorological tower providing synchronized, continuous three-component measurements of wind speed. Results reveal a pronounced, predominantly linear increase of the logarithmic power of ground motion velocity with rising mean horizontal wind speed at all recording stations. Measurements in rough, mountainous terrain further identify a strong dependency of wind-induced noise on surface characteristics, such as topography and, therefore, demonstrate the necessity to consider wind direction as well. To assess the noise level of seismological recordings with respect to a dynamically changing wind field, we develop a methodology to account for the dependency of power spectral density of ground motion velocity on wind speed and wind direction for long, statistically significant periods. We further introduce the quantitative measure of the ground motion susceptibility to estimate the vulnerability of seismological recordings to the presence of wind.

Ground Motion Relations While TBM Drilling in Unconsolidated Sediments

NASA Astrophysics Data System (ADS)

Grund, Michael; Ritter, Joachim R. R.; Gehrig, Manuel

2016-05-01

The induced ground motions due to the tunnel boring machine (TBM), which has been used for the drilling of the urban metro tunnel in Karlsruhe (SW Germany), has been studied using the continuous recordings of seven seismological monitoring stations. The drilling has been undertaken in unconsolidated sediments of the Rhine River system, relatively close to the surface at 6-20 m depth and in the vicinity of many historic buildings. Compared to the reference values of DIN 4150-3 (1-80 Hz), no exceedance of the recommended peak ground velocity (PGV) limits (3-5 mm/s) was observed at the single recording site locations on building basements during the observation period between October 2014 and February 2015. Detailed analyses in the time and frequency domains helped with the detection of the sources of several specific shaking signals in the recorded time series and with the comparison of the aforementioned TBM-induced signals. The amplitude analysis allowed for the determination of a PGV attenuation relation (quality factor Q ~ 30-50) and the comparison of the TBM-induced ground motion with other artificially induced and natural ground motions of similar amplitudes.

Single-particle and collective motion in unbound deformed 39Mg

NASA Astrophysics Data System (ADS)

Fossez, K.; Rotureau, J.; Michel, N.; Liu, Quan; Nazarewicz, W.

2016-11-01

Background: Deformed neutron-rich magnesium isotopes constitute a fascinating territory where the interplay between collective rotation and single-particle motion is strongly affected by the neutron continuum. The unbound f p -shell nucleus 39Mg is an ideal candidate to study this interplay. Purpose: In this work, we predict the properties of low-lying resonant states of 39Mg, using a suite of realistic theoretical approaches rooted in the open quantum system framework. Method: To describe the spectrum and decay modes of 39Mg we use the conventional shell model, Gamow shell model, resonating group method, density matrix renormalization group method, and the nonadiabatic particle-plus-rotor model formulated in the Berggren basis. Results: The unbound ground state of 39Mg is predicted to be either a Jπ=7/2 - state or a 3/2 - state. A narrow Jπ=7/2 - ground-state candidate exhibits a resonant structure reminiscent of that of its one-neutron halo neighbor 37Mg, which is dominated by the f7 /2 partial wave at short distances and a p3 /2 component at large distances. A Jπ=3/2 - ground-state candidate is favored by the large deformation of the system. It can be associated with the 1/2 -[321 ] Nilsson orbital dominated by the ℓ =1 wave; hence its predicted width is large. The excited Jπ=1/2 - and 5 /2- states are expected to be broad resonances, while the Jπ=9/2 - and 11/2 - members of the ground-state rotational band are predicted to have very small neutron decay widths. Conclusion: We demonstrate that the subtle interplay between deformation, shell structure, and continuum coupling can result in a variety of excitations in an unbound nucleus just outside the neutron drip line.

Ground motions at the outermost limits of seismically triggered landslides

NASA Astrophysics Data System (ADS)

Jibson, Randall W.; Harp, Edwin L.

2016-04-01

Over the last few decades, we and our colleagues have conducted field investigations in which we mapped the outermost limits of triggered landslides in four earthquakes: 1987 Whittier Narrows, California (M 5.9), 1987 Superstition Hills, California (M 6.5), 1994 Northridge, California (M 6.7), and 2011 Mineral, Virginia (M 5.8). In an additional two earthquakes, 1976 Guatemala (M 7.5) and 1983 Coalinga, California (M 6.5), we determined limits using high-resolution aerial photographic interpretation in conjunction with more limited ground investigation. Limits in these earthquakes were defined by the locations of the very smallest failures (< 1 m^3) from the most susceptible slopes that can be identified positively as having been triggered by earthquake shaking. Because we and our colleagues conducted all of these investigations, consistent methodology and criteria were used in determining limits. In the six earthquakes examined, we correlated the outermost landslide limits with peak ground accelerations (PGA) from ShakeMap models of each earthquake. For the four earthquakes studied by field investigation, the minimum PGA values associated with farthest landslide limits ranged from 0.02-0.08 g. The range for the two earthquakes investigated using aerial photographic interpretations was 0.05-0.11 g. Although PGA values at landslide limits depend on several factors - including material strength, topographic amplification, and hydrologic conditions - these values provide an empirically useful lower limiting range of PGA needed to trigger the smallest failures on very susceptible slopes. In a well-recorded earthquake, this PGA range can be used to identify an outer boundary within which we might expect to find landsliding; in earthquakes that are not well recorded, mapping the outermost landslide limits provides a useful clue about ground-motion levels at the mapped limits.

Testing long-period ground-motion simulations of scenario earthquakes using the Mw 7.2 El Mayor-Cucapah mainshock: Evaluation of finite-fault rupture characterization and 3D seismic velocity models

USGS Publications Warehouse

Graves, Robert W.; Aagaard, Brad T.

2011-01-01

Using a suite of five hypothetical finite-fault rupture models, we test the ability of long-period (T>2.0 s) ground-motion simulations of scenario earthquakes to produce waveforms throughout southern California consistent with those recorded during the 4 April 2010 Mw 7.2 El Mayor-Cucapah earthquake. The hypothetical ruptures are generated using the methodology proposed by Graves and Pitarka (2010) and require, as inputs, only a general description of the fault location and geometry, event magnitude, and hypocenter, as would be done for a scenario event. For each rupture model, two Southern California Earthquake Center three-dimensional community seismic velocity models (CVM-4m and CVM-H62) are used, resulting in a total of 10 ground-motion simulations, which we compare with recorded ground motions. While the details of the motions vary across the simulations, the median levels match the observed peak ground velocities reasonably well, with the standard deviation of the residuals generally within 50% of the median. Simulations with the CVM-4m model yield somewhat lower variance than those with the CVM-H62 model. Both models tend to overpredict motions in the San Diego region and underpredict motions in the Mojave desert. Within the greater Los Angeles basin, the CVM-4m model generally matches the level of observed motions, whereas the CVM-H62 model tends to overpredict the motions, particularly in the southern portion of the basin. The variance in the peak velocity residuals is lowest for a rupture that has significant shallow slip (<5 km depth), whereas the variance in the residuals is greatest for ruptures with large asperities below 10 km depth. Overall, these results are encouraging and provide confidence in the predictive capabilities of the simulation methodology, while also suggesting some regions in which the seismic velocity models may need improvement.

Source Rupture Process for the February 21, 2011, Mw6.1, New Zealand Earthquake and the Characteristics of Near-field Strong Ground Motion

NASA Astrophysics Data System (ADS)

Meng, L.; Shi, B.

2011-12-01

The New Zealand Earthquake of February 21, 2011, Mw 6.1 occurred in the South Island, New Zealand with the epicenter at longitude 172.70°E and latitude 43.58°S, and with depth of 5 km. The Mw 6.1 earthquake occurred on an unknown blind fault involving oblique-thrust faulting, which is 9 km away from southern of the Christchurch, the third largest city of New Zealand, with a striking direction from east toward west (United State Geology Survey, USGS, 2011). The earthquake killed at least 163 people and caused a lot of construction damages in Christchurch city. The Peak Ground Acceleration (PGA) observed at station Heathcote Valley Primary School (HVSC), which is 1 km away from the epicenter, is up to almost 2.0g. The ground-motion observation suggests that the buried earthquake source generates much higher near-fault ground motion. In this study, we have analyzed the earthquake source spectral parameters based on the strong motion observations, and estimated the near-fault ground motion based on the Brune's circular fault model. The results indicate that the larger ground motion may be caused by a higher dynamic stress drop,Δσd , or effect stress drop named by Brune, in the major source rupture region. In addition, a dynamical composite source model (DCSM) has been developed to simulate the near-fault strong ground motion with associated fault rupture properties from the kinematic point of view. For comparison purpose, we also conducted the broadband ground motion predictions for the station of HVSC; the synthetic seismogram of time histories produced for this station has good agreement with the observations in the waveforms, peak values and frequency contents, which clearly indicate that the higher dynamic stress drop during the fault rupture may play an important role to the anomalous ground-motion amplification. The preliminary simulated result illustrated in at Station HVSC is that the synthetics seismograms have a realistic appearance in the waveform and time duration to the observations, especially for the vertical component. Synthetics Fourier spectra are reasonably similar to the recordings. The simulated PGA values of vertical and S26W components are consistent with the recorded, and for the S64E component, the PGA derived from our simulation is smaller than that from observation. The resultant Fourier spectra both for the synthetic and observation is much similar with each other for three components of acceleration time histories, except for the vertical component, where the derived spectra from synthetic data is smaller than that resultant from observation when the frequency is above 10 Hz. Both theoretical study and numerical simulation indicate that, for the 2011 Mw 6.1, New Zealand Earthquake, the higher dynamic stress drop during the source rupture process could play an important role to the anomalous ground-motion amplification beside to the other site-related seismic effects. The composite source modeling based on the simple Brune's pulse model could approximately provide us a good insight into earthquake source related rupture processes for a moderate-sized earthquake.

Analysis of the variability in ground-motion synthesis and inversion

USGS Publications Warehouse

Spudich, Paul A.; Cirella, Antonella; Scognamiglio, Laura; Tinti, Elisa

2017-12-07

In almost all past inversions of large-earthquake ground motions for rupture behavior, the goal of the inversion is to find the “best fitting” rupture model that predicts ground motions which optimize some function of the difference between predicted and observed ground motions. This type of inversion was pioneered in the linear-inverse sense by Olson and Apsel (1982), who minimized the square of the difference between observed and simulated motions (“least squares”) while simultaneously minimizing the rupture-model norm (by setting the null-space component of the rupture model to zero), and has been extended in many ways, one of which is the use of nonlinear inversion schemes such as simulated annealing algorithms that optimize some other misfit function. For example, the simulated annealing algorithm of Piatanesi and others (2007) finds the rupture model that minimizes a “cost” function which combines a least-squares and a waveform-correlation measure of misfit.All such inversions that look for a unique “best” model have at least three problems. (1) They have removed the null-space component of the rupture model—that is, an infinite family of rupture models that all fit the data equally well have been narrowed down to a single model. Some property of interest in the rupture model might have been discarded in this winnowing process. (2) Smoothing constraints are commonly used to yield a unique “best” model, in which case spatially rough rupture models will have been discarded, even if they provide a good fit to the data. (3) No estimate of confidence in the resulting rupture models can be given because the effects of unknown errors in the Green’s functions (“theory errors”) have not been assessed. In inversion for rupture behavior, these theory errors are generally larger than the data errors caused by ground noise and instrumental limitations, and so overfitting of the data is probably ubiquitous for such inversions.Recently, attention has turned to the inclusion of theory errors in the inversion process. Yagi and Fukahata (2011) made an important contribution by presenting a method to estimate the uncertainties in predicted large-earthquake ground motions due to uncertainties in the Green’s functions. Here we derive their result and compare it with the results of other recent studies that look at theory errors in a Bayesian inversion context particularly those by Bodin and others (2012), Duputel and others (2012), Dettmer and others (2014), and Minson and others (2014).Notably, in all these studies, the estimates of theory error were obtained from theoretical considerations alone; none of the investigators actually measured Green’s function errors. Large earthquakes typically have aftershocks, which, if their rupture surfaces are physically small enough, can be considered point evaluations of the real Green’s functions of the Earth. Here we simulate smallaftershock ground motions with (erroneous) theoretical Green’s functions. Taking differences between aftershock ground motions and simulated motions to be the “theory error,” we derive a statistical model of the sources of discrepancies between the theoretical and real Green’s functions. We use this model with an extended frequency-domain version of the time-domain theory of Yagi and Fukahata (2011) to determine the expected variance 2 τ caused by Green’s function error in ground motions from a larger (nonpoint) earthquake that we seek to model.We also differ from the above-mentioned Bayesian inversions in our handling of the nonuniqueness problem of seismic inversion. We follow the philosophy of Segall and Du (1993), who, instead of looking for a best-fitting model, looked for slip models that answered specific questions about the earthquakes they studied. In their Bayesian inversions, they inductively derived a posterior probability-density function (PDF) for every model parameter. We instead seek to find two extremal rupture models whose ground motions fit the data within the error bounds given by 2 τ , as quantified by using a chi-squared test described below. So, we can ask questions such as, “What are the rupture models with the highest and lowest average rupture speed consistent with the theory errors?” Having found those models, we can then say with confidence that the true rupture speed is somewhere between those values. Although the Bayesian approach gives a complete solution to the inverse problem, it is computationally demanding: Minson and others (2014) needed 1010 forward kinematic simulations to derive their posterior probability distribution. In our approach, only about107 simulations are needed. Moreover, in practical application, only a small set of rupture models may be needed to answer the relevant questions—for example, determining the maximum likelihood solution (achievable through standard inversion techniques) and the two rupture models bounding some property of interest.The specific property that we wish to investigate is the correlation between various rupturemodel parameters, such as peak slip velocity and rupture velocity, in models of real earthquakes. In some simulations of ground motions for hypothetical large earthquakes, such as those by Aagaard and others (2010) and the Southern California Earthquake Center Broadband Simulation Platform (Graves and Pitarka, 2015), rupture speed is assumed to correlate locally with peak slip, although there is evidence that rupture speed should correlate better with peak slip speed, owing to its dependence on local stress drop. We may be able to determine ways to modify Piatanesi and others’s (2007) inversion’s “cost” function to find rupture models with either high or low degrees of correlation between pairs of rupture parameters. We propose a cost function designed to find these two extremal models.

Probabilistic seismic hazard analysis for Sumatra, Indonesia and across the Southern Malaysian Peninsula

USGS Publications Warehouse

Petersen, M.D.; Dewey, J.; Hartzell, S.; Mueller, C.; Harmsen, S.; Frankel, A.D.; Rukstales, K.

2004-01-01

The ground motion hazard for Sumatra and the Malaysian peninsula is calculated in a probabilistic framework, using procedures developed for the US National Seismic Hazard Maps. We constructed regional earthquake source models and used standard published and modified attenuation equations to calculate peak ground acceleration at 2% and 10% probability of exceedance in 50 years for rock site conditions. We developed or modified earthquake catalogs and declustered these catalogs to include only independent earthquakes. The resulting catalogs were used to define four source zones that characterize earthquakes in four tectonic environments: subduction zone interface earthquakes, subduction zone deep intraslab earthquakes, strike-slip transform earthquakes, and intraplate earthquakes. The recurrence rates and sizes of historical earthquakes on known faults and across zones were also determined from this modified catalog. In addition to the source zones, our seismic source model considers two major faults that are known historically to generate large earthquakes: the Sumatran subduction zone and the Sumatran transform fault. Several published studies were used to describe earthquakes along these faults during historical and pre-historical time, as well as to identify segmentation models of faults. Peak horizontal ground accelerations were calculated using ground motion prediction relations that were developed from seismic data obtained from the crustal interplate environment, crustal intraplate environment, along the subduction zone interface, and from deep intraslab earthquakes. Most of these relations, however, have not been developed for large distances that are needed for calculating the hazard across the Malaysian peninsula, and none were developed for earthquake ground motions generated in an interplate tectonic environment that are propagated into an intraplate tectonic environment. For the interplate and intraplate crustal earthquakes, we have applied ground-motion prediction relations that are consistent with California (interplate) and India (intraplate) strong motion data that we collected for distances beyond 200 km. For the subduction zone equations, we recognized that the published relationships at large distances were not consistent with global earthquake data that we collected and modified the relations to be compatible with the global subduction zone ground motions. In this analysis, we have used alternative source and attenuation models and weighted them to account for our uncertainty in which model is most appropriate for Sumatra or for the Malaysian peninsula. The resulting peak horizontal ground accelerations for 2% probability of exceedance in 50 years range from over 100% g to about 10% g across Sumatra and generally less than 20% g across most of the Malaysian peninsula. The ground motions at 10% probability of exceedance in 50 years are typically about 60% of the ground motions derived for a hazard level at 2% probability of exceedance in 50 years. The largest contributors to hazard are from the Sumatran faults.

Site-specific seismic ground motion analyses for transportation infrastructure in the New Madrid seismic zone.

DOT National Transportation Integrated Search

2012-11-01

Generic, code-based design procedures cannot account for the anticipated short-period attenuation and long-period amplification of earthquake ground motions in the deep, soft sediments of the Mississippi Embayment within the New Madrid Seismic Zone (...

A media-based assessment of damage and ground motions from the January 26th, 2001 M 7.6 Bhuj, India earthquake

USGS Publications Warehouse

Hough, S.E.; Martin, S.; Bilham, R.; Atkinson, G.M.

2003-01-01

We compiled available news and internet accounts of damage and other effects from the 26th January, 2001, Bhuj earthquake, and interpreted them to obtain modified Mercalli intensities at over 200 locations throughout the Indian subcontinent. These values are used to map the intensity distribution using a simple mathematical interpolation method. The maps reveal several interesting features. Within the Kachchh region, the most heavily damaged villages are concentrated towards the western edge of the inferred fault, consistent with western directivity. Significant sediment-induced amplification is also suggested at a number of locations around the Gulf of Kachchh to the south of the epicenter. Away from the Kachchh region intensities were clearly amplified significantly in areas that are along rivers, within deltas, or on coastal alluvium such as mud flats and salt pans. In addition we use fault rupture parameters inferred from teleseismic data to predict shaking intensity at distances of 0-1000 km. We then convert the predicted hard rock ground motion parameters to MMI using a relationship (derived from internet-based intensity surveys) that assigns MMI based on the average effects in a region. The predicted MMIs are typically lower by 1-2 units than those estimated from news accounts. This discrepancy is generally consistent with the expected effect of sediment response, but it could also reflect other factors such as a tendency for media accounts to focus on the most dramatic damage, rather than the average effects. Our modeling results also suggest, however, that the Bhuj earthquake generated more high-frequency shaking than is expected for earthquakes of similar magnitude in California, and may therefore have been especially damaging.

3-D velocity structure model for long-period ground motion simulation of the hypothetical Nankai Earthquake

NASA Astrophysics Data System (ADS)

Kagawa, T.; Petukhin, A.; Koketsu, K.; Miyake, H.; Murotani, S.; Tsurugi, M.

2010-12-01

Three dimensional velocity structure model of southwest Japan is provided to simulate long-period ground motions due to the hypothetical subduction earthquakes. The model is constructed from numerous physical explorations conducted in land and offshore areas and observational study of natural earthquakes. Any available information is involved to explain crustal structure and sedimentary structure. Figure 1 shows an example of cross section with P wave velocities. The model has been revised through numbers of simulations of small to middle earthquakes as to have good agreement with observed arrival times, amplitudes, and also waveforms including surface waves. Figure 2 shows a comparison between Observed (dash line) and simulated (solid line) waveforms. Low velocity layers have added on seismological basement to reproduce observed records. The thickness of the layer has been adjusted through iterative analysis. The final result is found to have good agreement with the results from other physical explorations; e.g. gravity anomaly. We are planning to make long-period (about 2 to 10 sec or longer) simulations of ground motion due to the hypothetical Nankai Earthquake with the 3-D velocity structure model. As the first step, we will simulate the observed ground motions of the latest event occurred in 1946 to check the source model and newly developed velocity structure model. This project is partly supported by Integrated Research Project for Long-Period Ground Motion Hazard Maps by Ministry of Education, Culture, Sports, Science and Technology (MEXT). The ground motion data used in this study were provided by National Research Institute for Earth Science and Disaster Prevention Disaster (NIED). Figure 1 An example of cross section with P wave velocities Figure 2 Observed (dash line) and simulated (solid line) waveforms due to a small earthquake

Real time numerical shake prediction incorporating attenuation structure: a case for the 2016 Kumamoto Earthquake

NASA Astrophysics Data System (ADS)

Ogiso, M.; Hoshiba, M.; Shito, A.; Matsumoto, S.

2016-12-01

Needless to say, heterogeneous attenuation structure is important for ground motion prediction, including earthquake early warning, that is, real time ground motion prediction. Hoshiba and Ogiso (2015, AGU Fall meeting) showed that the heterogeneous attenuation and scattering structure will lead to earlier and more accurate ground motion prediction in the numerical shake prediction scheme proposed by Hoshiba and Aoki (2015, BSSA). Hoshiba and Ogiso (2015) used assumed heterogeneous structure, and we discuss the effect of them in the case of 2016 Kumamoto Earthquake, using heterogeneous structure estimated by actual observation data. We conducted Multiple Lapse Time Window Analysis (Hoshiba, 1993, JGR) to the seismic stations located on western part of Japan to estimate heterogeneous attenuation and scattering structure. The characteristics are similar to the previous work of Carcole and Sato (2010, GJI), e.g. strong intrinsic and scattering attenuation around the volcanoes located on the central part of Kyushu, and relatively weak heterogeneities in the other area. Real time ground motion prediction simulation for the 2016 Kumamoto Earthquake was conducted using the numerical shake prediction scheme with 474 strong ground motion stations. Comparing the snapshot of predicted and observed wavefield showed a tendency for underprediction around the volcanic area in spite of the heterogeneous structure. These facts indicate the necessity of improving the heterogeneous structure for the numerical shake prediction scheme.In this study, we used the waveforms of Hi-net, K-NET, KiK-net stations operated by the NIED for estimating structure and conducting ground motion prediction simulation. Part of this study was supported by the Earthquake Research Institute, the University of Tokyo cooperative research program and JSPS KAKENHI Grant Number 25282114.

The Engineering Strong Ground Motion Network of the National Autonomous University of Mexico

NASA Astrophysics Data System (ADS)

Velasco Miranda, J. M.; Ramirez-Guzman, L.; Aguilar Calderon, L. A.; Almora Mata, D.; Ayala Hernandez, M.; Castro Parra, G.; Molina Avila, I.; Mora, A.; Torres Noguez, M.; Vazquez Larquet, R.

2014-12-01

The coverage, design, operation and monitoring capabilities of the strong ground motion program at the Institute of Engineering (IE) of the National Autonomous University of Mexico (UNAM) is presented. Started in 1952, the seismic instrumentation intended initially to bolster earthquake engineering projects in Mexico City has evolved into the largest strong ground motion monitoring system in the region. Today, it provides information not only to engineering projects, but also to the near real-time risk mitigation systems of the country, and enhances the general understanding of the effects and causes of earthquakes in Mexico. The IE network includes more than 100 free-field stations and several buildings, covering the largest urban centers and zones of significant seismicity in Central Mexico. Of those stations, approximately one-fourth send the observed acceleration to a processing center in Mexico City continuously, and the rest require either periodic visits for the manual recovery of the data or remote interrogation, for later processing and cataloging. In this research, we document the procedures and telecommunications systems used systematically to recover information. Additionally, we analyze the spatial distribution of the free-field accelerographs, the quality of the instrumentation, and the recorded ground motions. The evaluation criteria are based on the: 1) uncertainty in the generation of ground motion parameter maps due to the spatial distribution of the stations, 2) potential of the array to provide localization and magnitude estimates for earthquakes with magnitudes greater than Mw 5, and 3) adequacy of the network for the development of Ground Motion Prediction Equations due to intra-plate and intra-slab earthquakes. We conclude that the monitoring system requires a new redistribution, additional stations, and a substantial improvement in the instrumentation and telecommunications. Finally, we present an integral plan to improve the current network's monitoring capabilities.

Ground motion modeling of the 1906 San Francisco earthquake II: Ground motion estimates for the 1906 earthquake and scenario events

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

Aagaard, B; Brocher, T; Dreger, D

2007-02-09

We estimate the ground motions produced by the 1906 San Francisco earthquake making use of the recently developed Song et al. (2008) source model that combines the available geodetic and seismic observations and recently constructed 3D geologic and seismic velocity models. Our estimates of the ground motions for the 1906 earthquake are consistent across five ground-motion modeling groups employing different wave propagation codes and simulation domains. The simulations successfully reproduce the main features of the Boatwright and Bundock (2005) ShakeMap, but tend to over predict the intensity of shaking by 0.1-0.5 modified Mercalli intensity (MMI) units. Velocity waveforms at sitesmore » throughout the San Francisco Bay Area exhibit characteristics consistent with rupture directivity, local geologic conditions (e.g., sedimentary basins), and the large size of the event (e.g., durations of strong shaking lasting tens of seconds). We also compute ground motions for seven hypothetical scenarios rupturing the same extent of the northern San Andreas fault, considering three additional hypocenters and an additional, random distribution of slip. Rupture directivity exerts the strongest influence on the variations in shaking, although sedimentary basins do consistently contribute to the response in some locations, such as Santa Rosa, Livermore, and San Jose. These scenarios suggest that future large earthquakes on the northern San Andreas fault may subject the current San Francisco Bay urban area to stronger shaking than a repeat of the 1906 earthquake. Ruptures propagating southward towards San Francisco appear to expose more of the urban area to a given intensity level than do ruptures propagating northward.« less

How sensitive is earthquake ground motion to source parameters? Insights from a numerical study in the Mygdonian basin

NASA Astrophysics Data System (ADS)

Chaljub, Emmanuel; Maufroy, Emeline; deMartin, Florent; Hollender, Fabrice; Guyonnet-Benaize, Cédric; Manakou, Maria; Savvaidis, Alexandros; Kiratzi, Anastasia; Roumelioti, Zaferia; Theodoulidis, Nikos

2014-05-01

Understanding the origin of the variability of earthquake ground motion is critical for seismic hazard assessment. Here we present the results of a numerical analysis of the sensitivity of earthquake ground motion to seismic source parameters, focusing on the Mygdonian basin near Thessaloniki (Greece). We use an extended model of the basin (65 km [EW] x 50 km [NS]) which has been elaborated during the Euroseistest Verification and Validation Project. The numerical simulations are performed with two independent codes, both implementing the Spectral Element Method. They rely on a robust, semi-automated, mesh design strategy together with a simple homogenization procedure to define a smooth velocity model of the basin. Our simulations are accurate up to 4 Hz, and include the effects of surface topography and of intrinsic attenuation. Two kinds of simulations are performed: (1) direct simulations of the surface ground motion for real regional events having various back azimuth with respect to the center of the basin; (2) reciprocity-based calculations where the ground motion due to 980 different seismic sources is computed at a few stations in the basin. In the reciprocity-based calculations, we consider epicentral distances varying from 2.5 km to 40 km, source depths from 1 km to 15 km and we span the range of possible back-azimuths with a 10 degree bin. We will present some results showing (1) the sensitivity of ground motion parameters to the location and focal mechanism of the seismic sources; and (2) the variability of the amplification caused by site effects, as measured by standard spectral ratios, to the source characteristics

The 2018 and 2020 Updates of the U.S. National Seismic Hazard Models

NASA Astrophysics Data System (ADS)

Petersen, M. D.

2017-12-01

During 2018 the USGS will update the 2014 National Seismic Hazard Models by incorporating new seismicity models, ground motion models, site factors, fault inputs, and by improving weights to ground motion models using empirical and other data. We will update the earthquake catalog for the U.S. and introduce new rate models. Additional fault data will be used to improve rate estimates on active faults. New ground motion models (GMMs) and site factors for Vs30 have been released by the Pacific Earthquake Engineering Research Center (PEER) and we will consider these in assessing ground motions in craton and extended margin regions of the central and eastern U.S. The USGS will also include basin-depth terms for selected urban areas of the western United States to improve long-period shaking assessments using published depth estimates to 1.0 and 2.5 km/s shear wave velocities. We will produce hazard maps for input into the building codes that span a broad range of periods (0.1 to 5 s) and site classes (shear wave velocity from 2000 m/s to 200 m/s in the upper 30 m of the crust, Vs30). In the 2020 update we plan on including: a new national crustal model that defines basin depths required in the latest GMMs, new 3-D ground motion simulations for several urban areas, new magnitude-area equations, and new fault geodetic and geologic strain rate models. The USGS will also consider including new 3-D ground motion simulations for inclusion in these long-period maps. These new models are being evaluated and will be discussed at one or more regional and topical workshops held at the beginning of 2018.

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.

Ground-motion modeling of the 1906 San Francisco Earthquake, part II: Ground-motion estimates for the 1906 earthquake and scenario events

USGS Publications Warehouse

Aagaard, Brad T.; Brocher, T.M.; Dolenc, D.; Dreger, D.; Graves, R.W.; Harmsen, S.; Hartzell, S.; Larsen, S.; McCandless, K.; Nilsson, S.; Petersson, N.A.; Rodgers, A.; Sjogreen, B.; Zoback, M.L.

2008-01-01

We estimate the ground motions produce by the 1906 San Francisco earthquake making use of the recently developed Song et al. (2008) source model that combines the available geodetic and seismic observations and recently constructed 3D geologic and seismic velocity models. Our estimates of the ground motions for the 1906 earthquake are consistent across five ground-motion modeling groups employing different wave propagation codes and simulation domains. The simulations successfully reproduce the main features of the Boatwright and Bundock (2005) ShakeMap, but tend to over predict the intensity of shaking by 0.1-0.5 modified Mercalli intensity (MMI) units. Velocity waveforms at sites throughout the San Francisco Bay Area exhibit characteristics consistent with rupture directivity, local geologic conditions (e.g., sedimentary basins), and the large size of the event (e.g., durations of strong shaking lasting tens of seconds). We also compute ground motions for seven hypothetical scenarios rupturing the same extent of the northern San Andreas fault, considering three additional hypocenters and an additional, random distribution of slip. Rupture directivity exerts the strongest influence on the variations in shaking, although sedimentary basins do consistently contribute to the response in some locations, such as Santa Rosa, Livermore, and San Jose. These scenarios suggest that future large earthquakes on the northern San Andreas fault may subject the current San Francisco Bay urban area to stronger shaking than a repeat of the 1906 earthquake. Ruptures propagating southward towards San Francisco appear to expose more of the urban area to a given intensity level than do ruptures propagating northward.

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

Aagaard, B T; Graves, R W; Rodgers, A

We simulate long-period (T > 1.0-2.0 s) and broadband (T > 0.1 s) ground motions for 39 scenarios earthquakes (Mw 6.7-7.2) involving the Hayward, Calaveras, and Rodgers Creek faults. For rupture on the Hayward fault we consider the effects of creep on coseismic slip using two different approaches, both of which reduce the ground motions compared with neglecting the influence of creep. Nevertheless, the scenario earthquakes generate strong shaking throughout the San Francisco Bay area with about 50% of the urban area experiencing MMI VII or greater for the magnitude 7.0 scenario events. Long-period simulations of the 2007 Mw 4.18more » Oakland and 2007 Mw 4.5 Alum Rock earthquakes show that the USGS Bay Area Velocity Model version 08.3.0 permits simulation of the amplitude and duration of shaking throughout the San Francisco Bay area, with the greatest accuracy in the Santa Clara Valley (San Jose area). The ground motions exhibit a strong sensitivity to the rupture length (or magnitude), hypocenter (or rupture directivity), and slip distribution. The ground motions display a much weaker sensitivity to the rise time and rupture speed. Peak velocities, peak accelerations, and spectral accelerations from the synthetic broadband ground motions are, on average, slightly higher than the Next Generation Attenuation (NGA) ground-motion prediction equations. We attribute at least some of this difference to the relatively narrow width of the Hayward fault ruptures. The simulations suggest that the Spudich and Chiou (2008) directivity corrections to the NGA relations could be improved by including a dependence on the rupture speed and increasing the areal extent of rupture directivity with period. The simulations also indicate that the NGA relations may under-predict amplification in shallow sedimentary basins.« less

Rotational motions from the 2016, Central Italy seismic sequence, as observed by an underground ring laser gyroscope

NASA Astrophysics Data System (ADS)

Simonelli, Andreino; Belfi, Jacopo; Beverini, Nicolò; Di Virgilio, Angela; Maccioni, Enrico; De Luca, Gaetano; Saccorotti, Gilberto; Wassermann, Joachim; Igel, Heiner

2017-04-01

We present analyses of rotational and translational ground motions from earthquakes recorded during October-November, 2016, in association with the Central Italy seismic-sequence. We use co-located measurements of the vertical ground rotation rate from a large ring laser gyroscope (RLG), and the three components of ground velocity from a broadband seismometer. Both instruments are positioned in a deep underground environment, within the Gran Sasso National Laboratories (LNGS) of the Istituto Nazionale di Fisica Nucleare (INFN). We collected dozen of events spanning the 3.5-5.9 Magnitude range, and epicentral distances between 40 km and 80 km. This data set constitutes an unprecedented observation of the vertical rotational motions associated with an intense seismic sequence at local distance. In theory - assuming plane wave propagation - the ratio between the vertical rotation rate and the transverse acceleration permits, in a single station approach, the estimation of apparent phase velocity in the case of SH arrivals or real phase velocity in the case of Love surface waves. This is a standard approach for the analysis of earthquakes at teleseismic distances, and the results reported by the literature are compatible with the expected phase velocities from the PREM model. Here we extend the application of the same approach to local events, thus exploring higher frequency ranges and larger rotation rate amplitudes. We use a novel approach to joint rotation/acceleration analysis based on the continuous wavelet transform (CWT). Wavelet coherence (WTC) is used as a filter for identifying those regions of the time-period plane where the rotation rate and transverse acceleration signals exhibit significant coherence. This allows retrieving estimates of phase velocities over the period range spanned by correlated arrivals. Coherency among ground rotation and translation is also observed throughout the coda of the P-wave arrival, an observation which is interpreted in terms of near-receiver P-SH converted energy due to 3D effects. Those particular coda waves, however, do exhibit a large variability in the rotation/acceleration ratio, as a likely consequence of differences in the wavepath and/or source mechanism.

Satellite-Tracking Millimeter-Wave Reflector Antenna System For Mobile Satellite-Tracking

NASA Technical Reports Server (NTRS)

Densmore, Arthur C. (Inventor); Jamnejad, Vahraz (Inventor); Woo, Kenneth E. (Inventor)

2001-01-01

A miniature dual-band two-way mobile satellite-tracking antenna system mounted on a movable vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.

29 CFR 102.65 - Motions; interventions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 2 2011-07-01 2011-07-01 false Motions; interventions. 102.65 Section 102.65 Labor... Act § 102.65 Motions; interventions. (a) All motions, including motions for intervention pursuant to... any proceeding shall make a motion for intervention, stating the grounds upon which such person claims...

29 CFR 102.65 - Motions; interventions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 2 2013-07-01 2013-07-01 false Motions; interventions. 102.65 Section 102.65 Labor... Act § 102.65 Motions; interventions. (a) All motions, including motions for intervention pursuant to... any proceeding shall make a motion for intervention, stating the grounds upon which such person claims...

29 CFR 102.65 - Motions; interventions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 2 2012-07-01 2012-07-01 false Motions; interventions. 102.65 Section 102.65 Labor... Act § 102.65 Motions; interventions. (a) All motions, including motions for intervention pursuant to... any proceeding shall make a motion for intervention, stating the grounds upon which such person claims...

29 CFR 102.65 - Motions; interventions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 29 Labor 2 2014-07-01 2014-07-01 false Motions; interventions. 102.65 Section 102.65 Labor... Act § 102.65 Motions; interventions. (a) All motions, including motions for intervention pursuant to... any proceeding shall make a motion for intervention, stating the grounds upon which such person claims...

Free fall and evaporation of N-Octane droplets in the atmosphere as applied to the jettisoning of aviation gasoline at altitude

NASA Technical Reports Server (NTRS)

Lowell, Herman H

1953-01-01

In connection with proposed rapid jettisoning of aviation gasoline at altitude, a theoretical study was made of the free fall and evaporation of N-octane droplets in the atmosphere ; N-octane was selected for study because of the expected similarity of over-all evaporation behavior of N-octane and gasoline. It was concluded that gasoline (or N-octane) droplets larger than 2000 microns in diameter would be unstable ; terminal speeds and Reynolds numbers were obtained for droplets not larger than 2000 microns at altitudes to 11,000 feet. The motion data were used in the calculation of N-octane evaporation rates under various conditions. It was found that a droplet having an original diameter of 2000 microns would fall about 4000 feet from 6000 feet under NACA standard atmosphere conditions before coming virtually to rest. Finally, it was concluded that temperature effects are of paramount importance; at highest air temperatures a 1000-foot ground clearance would probably be adequate to prevent ground contamination, whereas at lowest air temperatures only an atomizing spray arrangement would prevent ground contamination, irrespective of ground clearance.

Development of guidelines for incorporation of vertical ground motion effects in seismic design of highway bridges.

DOT National Transportation Integrated Search

2008-05-01

This study was undertaken with the objective of assessing the current provisions in SDC-2006 for incorporating : vertical effects of ground motions in seismic evaluation and design of ordinary highway bridges. A : comprehensive series of simulations ...

Effect of vertical ground motions on shear demand and capacity in bridge columns.

DOT National Transportation Integrated Search

2012-03-01

The objective of this project was to examine the effects of axial force variation in bridge columns due to strong vertical : ground motions and the influence of these axial force fluctuations on shear strength degradation. : Two quarter scale specime...

10 CFR 100.23 - Geologic and seismic siting criteria.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Earthquake Ground Motion, and to permit adequate engineering solutions to actual or potential geologic and..., earthquake recurrence rates, fault geometry and slip rates, site foundation material, and seismically induced... Earthquake Ground Motion for the site, the potential for surface tectonic and nontectonic deformations, the...

10 CFR 100.23 - Geologic and seismic siting criteria.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Earthquake Ground Motion, and to permit adequate engineering solutions to actual or potential geologic and..., earthquake recurrence rates, fault geometry and slip rates, site foundation material, and seismically induced... Earthquake Ground Motion for the site, the potential for surface tectonic and nontectonic deformations, the...

10 CFR 100.23 - Geologic and seismic siting criteria.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Earthquake Ground Motion, and to permit adequate engineering solutions to actual or potential geologic and..., earthquake recurrence rates, fault geometry and slip rates, site foundation material, and seismically induced... Earthquake Ground Motion for the site, the potential for surface tectonic and nontectonic deformations, the...

Structure-specific scalar intensity measures for near-source and ordinary earthquake ground motions

USGS Publications Warehouse

Luco, N.; Cornell, C.A.

2007-01-01

Introduced in this paper are several alternative ground-motion intensity measures (IMs) that are intended for use in assessing the seismic performance of a structure at a site susceptible to near-source and/or ordinary ground motions. A comparison of such IMs is facilitated by defining the "efficiency" and "sufficiency" of an IM, both of which are criteria necessary for ensuring the accuracy of the structural performance assessment. The efficiency and sufficiency of each alternative IM, which are quantified via (i) nonlinear dynamic analyses of the structure under a suite of earthquake records and (ii) linear regression analysis, are demonstrated for the drift response of three different moderate- to long-period buildings subjected to suites of ordinary and of near-source earthquake records. One of the alternative IMs in particular is found to be relatively efficient and sufficient for the range of buildings considered and for both the near-source and ordinary ground motions. ?? 2007, Earthquake Engineering Research Institute.

Benefits of rotational ground motions for planetary seismology

NASA Astrophysics Data System (ADS)

Donner, S.; Joshi, R.; Hadziioannou, C.; Nunn, C.; van Driel, M.; Schmelzbach, C.; Wassermann, J. M.; Igel, H.

2017-12-01

Exploring the internal structure of planetary objects is fundamental to understand the evolution of our solar system. In contrast to Earth, planetary seismology is hampered by the limited number of stations available, often just a single one. Classic seismology is based on the measurement of three components of translational ground motion. Its methods are mainly developed for a larger number of available stations. Therefore, the application of classical seismological methods to other planets is very limited. Here, we show that the additional measurement of three components of rotational ground motion could substantially improve the situation. From sparse or single station networks measuring translational and rotational ground motions it is possible to obtain additional information on structure and source. This includes direct information on local subsurface seismic velocities, separation of seismic phases, propagation direction of seismic energy, crustal scattering properties, as well as moment tensor source parameters for regional sources. The potential of this methodology will be highlighted through synthetic forward and inverse modeling experiments.

Toward resolving an earthquake ground motion mystery in west Seattle, Washington State: Shallow seismic focusing may cause anomalous chimney damage

USGS Publications Warehouse

Stephenson, W.J.; Frankel, A.D.; Odum, J.K.; Williams, R.A.; Pratt, T.L.

2006-01-01

A shallow bedrock fold imaged by a 1.3-km long high-resolution shear-wave seismic reflection profile in west Seattle focuses seismic waves arriving from the south. This focusing may cause a pocket of amplified ground shaking and the anomalous chimney damage observed in earthquakes of 1949, 1965 and 2001. The 200-m bedrock fold at ???300-m depth is caused by deformation across an inferred fault within the Seattle fault zone. Ground motion simulations, using the imaged geologic structure and northward-propagating north-dipping plane wave sources, predict a peak horizontal acceleration pattern that matches that observed in strong motion records of the 2001 Nisqually event. Additionally, a pocket of chimney damage reported for both the 1965 and the 2001 earthquakes generally coincides with a zone of simulated amplification caused by focusing. This study further demonstrates the significant impact shallow (<1km) crustal structures can have on earthquake ground-motion variability.

Mean and modal ϵ in the deaggregation of probabilistic ground motion

USGS Publications Warehouse

Harmsen, Stephen C.

2001-01-01

Mean and modal ϵ exhibit a wide variation geographically for any specified PE. Modal ϵ for the 2% in 50 yr PE exceeds 2 near the most active western California faults, is less than –1 near some less active faults of the western United States (principally in the Basin and Range), and may be less than 0 in areal fault zones of the central and eastern United States (CEUS). This geographic variation is useful for comparing probabilistic ground motions with ground motions from scenario earthquakes on dominating faults, often used in seismic-resistant provisions of building codes. An interactive seismic-hazard deaggregation menu item has been added to the USGS probabilistic seismic-hazard analysis Web site, http://geohazards.cr.usgs.gov/eq/, allowing visitors to compute mean and modal distance, magnitude, and ϵ corresponding to ground motions having mean return times from 250 to 5000 yr for any site in the United States.

Construction of Source Model of Huge Subduction Earthquakes for Strong Ground Motion Prediction

NASA Astrophysics Data System (ADS)

Iwata, T.; Asano, K.; Kubo, H.

2013-12-01

It is a quite important issue for strong ground motion prediction to construct the source model of huge subduction earthquakes. Iwata and Asano (2012, AGU) summarized the scaling relationships of large slip area of heterogeneous slip model and total SMGA sizes on seismic moment for subduction earthquakes and found the systematic change between the ratio of SMGA to the large slip area and the seismic moment. They concluded this tendency would be caused by the difference of period range of source modeling analysis. In this paper, we try to construct the methodology of construction of the source model for strong ground motion prediction for huge subduction earthquakes. Following to the concept of the characterized source model for inland crustal earthquakes (Irikura and Miyake, 2001; 2011) and intra-slab earthquakes (Iwata and Asano, 2011), we introduce the proto-type of the source model for huge subduction earthquakes and validate the source model by strong ground motion modeling.

How many records should be used in ASCE/SEI-7 ground motion scaling procedure?

USGS Publications Warehouse

Reyes, Juan C.; Kalkan, Erol

2012-01-01

U.S. national building codes refer to the ASCE/SEI-7 provisions for selecting and scaling ground motions for use in nonlinear response history analysis of structures. Because the limiting values for the number of records in the ASCE/SEI-7 are based on engineering experience, this study examines the required number of records statistically, such that the scaled records provide accurate, efficient, and consistent estimates of “true” structural responses. Based on elastic–perfectly plastic and bilinear single-degree-of-freedom systems, the ASCE/SEI-7 scaling procedure is applied to 480 sets of ground motions; the number of records in these sets varies from three to ten. As compared to benchmark responses, it is demonstrated that the ASCE/SEI-7 scaling procedure is conservative if fewer than seven ground motions are employed. Utilizing seven or more randomly selected records provides more accurate estimate of the responses. Selecting records based on their spectral shape and design spectral acceleration increases the accuracy and efficiency of the procedure.

Figure–ground discrimination behavior in Drosophila. I. Spatial organization of wing-steering responses

PubMed Central

Fox, Jessica L.; Aptekar, Jacob W.; Zolotova, Nadezhda M.; Shoemaker, Patrick A.; Frye, Mark A.

2014-01-01

The behavioral algorithms and neural subsystems for visual figure–ground discrimination are not sufficiently described in any model system. The fly visual system shares structural and functional similarity with that of vertebrates and, like vertebrates, flies robustly track visual figures in the face of ground motion. This computation is crucial for animals that pursue salient objects under the high performance requirements imposed by flight behavior. Flies smoothly track small objects and use wide-field optic flow to maintain flight-stabilizing optomotor reflexes. The spatial and temporal properties of visual figure tracking and wide-field stabilization have been characterized in flies, but how the two systems interact spatially to allow flies to actively track figures against a moving ground has not. We took a systems identification approach in flying Drosophila and measured wing-steering responses to velocity impulses of figure and ground motion independently. We constructed a spatiotemporal action field (STAF) – the behavioral analog of a spatiotemporal receptive field – revealing how the behavioral impulse responses to figure tracking and concurrent ground stabilization vary for figure motion centered at each location across the visual azimuth. The figure tracking and ground stabilization STAFs show distinct spatial tuning and temporal dynamics, confirming the independence of the two systems. When the figure tracking system is activated by a narrow vertical bar moving within the frontal field of view, ground motion is essentially ignored despite comprising over 90% of the total visual input. PMID:24198267

Performance of JMA Earthquake Early Warning for the 2011 off the Pacific coast of Tohoku Earthquake (Mw9.0)

NASA Astrophysics Data System (ADS)

Hoshiba, M.; Wakayama, A.; Ishigaki, Y.; Doi, K.

2011-12-01

This presentation outlines the Earthquake Early Warning of the Japan Meteorological Agency (JMA) for the 2011 off the Pacific coast of Tohoku Earthquake (Mw9.0). EEW has been operational nationwide in Japan by JMA since October, 2007. For JMA EEW, the hypocenter is determined by a combination of several techniques, using approximately 1,100 stations from the JMA network and the Hi-net network of NIED; magnitude is mainly from maximum displacement amplitudes. JMA EEWs are updated as available data increases with elapsed time. Accordingly EEWs are issued repeatedly with improving accuracy for a single earthquake. JMA EEWs are divided into two grades depending on the expected intensities. The JMA intensity scale is based on instrumental measurements in which not only the amplitude but also the frequency and duration of the shaking are considered. The 10-degree JMA intensity scale rounds off the instrumental intensity value to the integer. Intensities of 5 and 6 are divided into two degrees, namely 5-lower, 5-upper, 6-lower and 6-upper, respectively. Intensity 1 corresponds to ground motion that people can barely detect, and 7 is the upper limit. JMA EEWs are announced to general public when intensity 5-lower (or greater) is expected. The JMA EEW system was triggered for the Mw 9.0 earthquake when station OURI (138km from the epicenter) detected the initial P wave at 14:46:40.2 (Japan Standard Time). The first EEW, the first of 15 announcements, was issued 5.4 s later. The waveform started with small amplitude, which was comparable to noise level for displacement. The small amplitude does not indicate that the initial rupture of the Mw 9.0 event is large, and does not suggest a large magnitude event. By the fourth EEW, 8.6 s after the first trigger, the expected intensity exceeded the criteria of the warning to the general public. JMA issued the fourth EEW announcements to the general public of the Tohoku district, and then the warning was automatically broadcast through TV, radios and cellular phone mails, which was before the strong ground motion hit cities. The EEW was earlier than the S wave arrival, and more than 15 s earlier than the strong ground motion (intensity 5-lower or greater) everywhere in the district. The EEW system expected intensity of 4 in the Tokyo region in the twelfth to fifteenth (final) issues. But actual observations reached 5-upper, which is greater than the criterion of the warning to the general public. The underestimation can be attributed to the large extent of the later fault rupture. For several weeks after the mainshock, when earthquakes sometimes occurred simultaneously over the wide source region, the system became confused, and did not always determine the location and magnitude correctly. In 49 days from the mainshock to April 28, 2011, 70 EEWs were announced to general public, but actual observed intensities did not exceed 2 at any observation stations in 17 of the 70 events.

From Regional Hazard Assessment to Nuclear-Test-Ban Treaty Support - InSAR Ground Motion Services

NASA Astrophysics Data System (ADS)

Lege, T.; Kalia, A.; Gruenberg, I.; Frei, M.

2016-12-01

There are numerous scientific applications of InSAR methods in tectonics, earthquake analysis and other geologic and geophysical fields. Ground motion on local and regional scale measured and monitored via the application of the InSAR techniques provide scientists and engineers with plenty of new insights and further understanding of subsurface processes. However, the operational use of InSAR is not yet very widespread. To foster the operational utilization of the Copernicus Sentinel Satellites in the day-to-day business of federal, state and municipal work and planning BGR (Federal Institute for Geosciences and Natural Resources) initiated workshops with potential user groups. Through extensive reconcilement of interests and demands with scientific, technical, economic and governmental stakeholders (e.g. Ministries, Mining Authorities, Geological Surveys, Geodetic Surveys and Environmental Agencies on federal and state level, SMEs, German Aerospace Center) BGR developed the concept of the InSAR based German National Ground Motion Service. One important backbone for the nationwide ground motion service is the so-called Persistent Scatterer Interferometry Wide Area Product (WAP) approach developed with grants of European research funds. The presentation shows the implementation of the ground motion service and examples for product developments for operational supervision of mining, water resources management and spatial planning. Furthermore the contributions of Copernicus Sentinel 1 radar data in the context of CTBT are discussed. The DInSAR processing of Sentinel 1 IW (Interferometric Wide Swath) SAR acquisitions from January 1st and 13th Jan. 2016 allow for the first time a near real time ground motion measurement of the North Korean nuclear test site. The measured ground displacements show a strong spatio-temporal correlation to the calculated epicenter measured by teleseismic stations. We are convinced this way another space technique will soon contribute even further to secure better societal information needs.

Engineering applications of strong ground motion simulation

NASA Astrophysics Data System (ADS)

Somerville, Paul

1993-02-01

The formulation, validation and application of a procedure for simulating strong ground motions for use in engineering practice are described. The procedure uses empirical source functions (derived from near-source strong motion recordings of small earthquakes) to provide a realistic representation of effects such as source radiation that are difficult to model at high frequencies due to their partly stochastic behavior. Wave propagation effects are modeled using simplified Green's functions that are designed to transfer empirical source functions from their recording sites to those required for use in simulations at a specific site. The procedure has been validated against strong motion recordings of both crustal and subduction earthquakes. For the validation process we choose earthquakes whose source models (including a spatially heterogeneous distribution of the slip of the fault) are independently known and which have abundant strong motion recordings. A quantitative measurement of the fit between the simulated and recorded motion in this validation process is used to estimate the modeling and random uncertainty associated with the simulation procedure. This modeling and random uncertainty is one part of the overall uncertainty in estimates of ground motions of future earthquakes at a specific site derived using the simulation procedure. The other contribution to uncertainty is that due to uncertainty in the source parameters of future earthquakes that affect the site, which is estimated from a suite of simulations generated by varying the source parameters over their ranges of uncertainty. In this paper, we describe the validation of the simulation procedure for crustal earthquakes against strong motion recordings of the 1989 Loma Prieta, California, earthquake, and for subduction earthquakes against the 1985 Michoacán, Mexico, and Valparaiso, Chile, earthquakes. We then show examples of the application of the simulation procedure to the estimatation of the design response spectra for crustal earthquakes at a power plant site in California and for subduction earthquakes in the Seattle-Portland region. We also demonstrate the use of simulation methods for modeling the attenuation of strong ground motion, and show evidence of the effect of critical reflections from the lower crust in causing the observed flattening of the attenuation of strong ground motion from the 1988 Saguenay, Quebec, and 1989 Loma Prieta earthquakes.

Seismic Hazard and Risk Posed by the Mentawai Segment of the Sumatran Megathrust

NASA Astrophysics Data System (ADS)

Megawati, K.; Han, X.

2010-12-01

Several lines of evidence have indicated that the Mentawai segment of the Sumatran megathrust is very likely to rupture within the next few decades. The present study is to investigate seismic hazard and risk levels at major cities in Sumatra, Java, Singapore and the Malay Peninsula caused by the potential giant earthquakes. Two scenarios are considered. The first one is an Mw 8.6 earthquake rupturing the 280-km segment that has been locked since 1797; in the second scenario, rupture occurs along a 400-km segment covering the combined rupture areas of the 1797 and 1833 historical events, of which the southern portion has partially slipped on 12 and 13 September 2007, producing an Mw 8.8 earthquake. Simulation results indicate that ground motions produced by the hypothetical scenarios are strong enough to cause yielding to medium and high-rise buildings in many major cities in Sumatra. It is vital to ensure that the overall strength, stiffness and integrity of the structures are maintained throughout the entire duration of shaking. However, the ductile detailing in current practice is formulated based on an assumption that ground motions would last 20 to 40 seconds. This has not been tested for longer durations of three to five minutes, expected from giant earthquakes. In Singapore and Kuala Lumpur, only medium and high-rise buildings, especially those located on soft-soil sites, are at risk. Given that seismic design has not been required in both cities, and thus the resulting structures are relatively brittle, it is crucial to investigate their performance under moderate-amplitude, long-duration, ground motions. The present study also points out that the shift of response spectrum toward longer period range becomes prominent for sites located far from potential seismic sources, which should be carefully considered in formulation of future seismic codes for Singapore, Malaysia and Indonesia.

Do French macroseismic intensity observations agree with expectations from the European Seismic Hazard Model 2013?

NASA Astrophysics Data System (ADS)

Rey, Julien; Beauval, Céline; Douglas, John

2018-05-01

Probabilistic seismic hazard assessments are the basis of modern seismic design codes. To test fully a seismic hazard curve at the return periods of interest for engineering would require many thousands of years' worth of ground-motion recordings. Because strong-motion networks are often only a few decades old (e.g. in mainland France the first accelerometric network dates from the mid-1990s), data from such sensors can be used to test hazard estimates only at very short return periods. In this article, several hundreds of years of macroseismic intensity observations for mainland France are interpolated using a robust kriging-with-a-trend technique to establish the earthquake history of every French mainland municipality. At 24 selected cities representative of the French seismic context, the number of exceedances of intensities IV, V and VI is determined over time windows considered complete. After converting these intensities to peak ground accelerations using the global conversion equation of Caprio et al. (Ground motion to intensity conversion equations (GMICEs): a global relationship and evaluation of regional dependency, Bulletin of the Seismological Society of America 105:1476-1490, 2015), these exceedances are compared with those predicted by the European Seismic Hazard Model 2013 (ESHM13). In half of the cities, the number of observed exceedances for low intensities (IV and V) is within the range of predictions of ESHM13. In the other half of the cities, the number of observed exceedances is higher than the predictions of ESHM13. For intensity VI, the match is closer, but the comparison is less meaningful due to a scarcity of data. According to this study, the ESHM13 underestimates hazard in roughly half of France, even when taking into account the uncertainty in the conversion from intensity to acceleration. However, these results are valid only for the acceleration range tested in this study (0.01 to 0.09 g).

Do French macroseismic intensity observations agree with expectations from the European Seismic Hazard Model 2013?

NASA Astrophysics Data System (ADS)

Rey, Julien; Beauval, Céline; Douglas, John

2018-02-01

Probabilistic seismic hazard assessments are the basis of modern seismic design codes. To test fully a seismic hazard curve at the return periods of interest for engineering would require many thousands of years' worth of ground-motion recordings. Because strong-motion networks are often only a few decades old (e.g. in mainland France the first accelerometric network dates from the mid-1990s), data from such sensors can be used to test hazard estimates only at very short return periods. In this article, several hundreds of years of macroseismic intensity observations for mainland France are interpolated using a robust kriging-with-a-trend technique to establish the earthquake history of every French mainland municipality. At 24 selected cities representative of the French seismic context, the number of exceedances of intensities IV, V and VI is determined over time windows considered complete. After converting these intensities to peak ground accelerations using the global conversion equation of Caprio et al. (Ground motion to intensity conversion equations (GMICEs): a global relationship and evaluation of regional dependency, Bulletin of the Seismological Society of America 105:1476-1490, 2015), these exceedances are compared with those predicted by the European Seismic Hazard Model 2013 (ESHM13). In half of the cities, the number of observed exceedances for low intensities (IV and V) is within the range of predictions of ESHM13. In the other half of the cities, the number of observed exceedances is higher than the predictions of ESHM13. For intensity VI, the match is closer, but the comparison is less meaningful due to a scarcity of data. According to this study, the ESHM13 underestimates hazard in roughly half of France, even when taking into account the uncertainty in the conversion from intensity to acceleration. However, these results are valid only for the acceleration range tested in this study (0.01 to 0.09 g).

Ground Motions Simulations and Site Effects in the Quito Basin (Ecuador)

NASA Astrophysics Data System (ADS)

Courboulex, F.; Castro-Cruz, D.; Laurendeau, A.; Bonilla, L. F.; Bertrand, E.; Mercerat, D.; Alvarado, A. P.

2017-12-01

The city of Quito (3M inhabitants), capital of Ecuador has been damaged several times in the past by large earthquakes. It is built on the hanging-wall of an active reverse fault, constituting a piggy-back basin. The deep structure of this basin and its seismic response remains badly known. We first use the recordings of 170 events on 18 accelerometers from the Quito permanent network and perform spectral ratio analysis. We find that the southern part of Quito shows strong site amplification at low frequency ( 0.35 Hz). Yet, high frequency ( 5 Hz) amplifications also exist, but exhibit a complex spatial variability. We then propose a new calibrated method based on empirical Green's functions (EGF) to simulate the ground motions due to a future earthquake in Quito. The idea is to use the results of a global database of source time functions (i.e., the SCARDEC database, Vallée and Douet, 2016; Courboulex et al., 2016) to define the average values and the variability of the stress-drop ratio parameter, which strongly affects the resulting simulations. We test the method on a Mw 7.8 event, similar in location and focal mechanism to the Pedernales earthquake that occurred on April 16th 2016 on the subduction zone. For this aim, we use the recordings of 6 aftershocks of magnitude 5.6 to 6.2 as EGF's. The predicted Fourier spectra, peak values and response spectra we obtain are in good agreement with real data from the 2016 event recorded on the Quito network. With the constraints we impose on stress-drop ratios, we expect that the simulated ground motions be representative of the variability of other Pedernales-type events that could occur in the future. Our results also well reproduce the low frequency site effects amplification in the south of the basin. This amplification could be particularly dangerous in the case of a mega subduction earthquake, like the one that struck Ecuador in 1906.

Site Amplification in the Central U.S.: Towards and understanding of factors influencing the site effect

NASA Astrophysics Data System (ADS)

Yassminh, R.; Sandvol, E. A.

2017-12-01

We have mapped site amplification using a Reverse Two Station (RTS) approach across much of the Central United States. We have found several unexpected results including a lack of amplification in Paleozoic basins such as the Illinois and Michigan basins. In general, we found that the amplification of high frequency regional waves is related to the topography. We also suggest that the HVSR spectra are primarily a function of the shallow velocity structure. The Central United States Seismic Observatory (CUSSO) is a vertical seismic array located adjacent to the central segment of the NMSZ. CUSSO data gives us the opportunity to understand the amplification of the ground motion at different depths within the uppermost crust. Simulating ground motions throughout the CUSSO borehole and examining the factors affecting the ground amplification, such as the velocity and thicknesses of the model layers and the source sizes, is an effective way to understand the role different factors playing in modifying the ground motion for both the local and regional seismic phases. We have used the spectral-element method (SEMs) with a 1D crustal velocity structure derived from logging data taken from CUSSO borehole. This model is comprised of near surface sediment layers and a Paleozoic basement. Utilizing the software package SPECFEM2D with virtual seismometers located on the surface and in the bottom of the different sediment layers, we have computed the true synthetic site amplification for frequencies between 0.01-3 Hz. For the local model, we have tested the sensitivity of the ground motion amplification to the source magnitude. For frequencies>0.6, the ground motions have been amplified with decreasing the magnitudes while for HZ<0.6 the the horizontal amplification increases with increasing the magnitudes. The effect of the velocity of the upper 30m was tested and the result shows that decreasing the Vs30m resulted in amplifying of the ground motion and decreasing of the resonant frequency. The velocity of the lower part of the sediment basin modifies the ground motion amplification and the result shows that increasing the velocity resulted in shifting the horizontal amplification peak frequency toward a lower frequency and increasing the amplification for frequencies >2Hz.

Rrsm: The European Rapid Raw Strong-Motion Database

NASA Astrophysics Data System (ADS)

Cauzzi, C.; Clinton, J. F.; Sleeman, R.; Domingo Ballesta, J.; Kaestli, P.; Galanis, O.

2014-12-01

We introduce the European Rapid Raw Strong-Motion database (RRSM), a Europe-wide system that provides parameterised strong motion information, as well as access to waveform data, within minutes of the occurrence of strong earthquakes. The RRSM significantly differs from traditional earthquake strong motion dissemination in Europe, which has focused on providing reviewed, processed strong motion parameters, typically with significant delays. As the RRSM provides rapid open access to raw waveform data and metadata and does not rely on external manual waveform processing, RRSM information is tailored to seismologists and strong-motion data analysts, earthquake and geotechnical engineers, international earthquake response agencies and the educated general public. Access to the RRSM database is via a portal at http://www.orfeus-eu.org/rrsm/ that allows users to query earthquake information, peak ground motion parameters and amplitudes of spectral response; and to select and download earthquake waveforms. All information is available within minutes of any earthquake with magnitude ≥ 3.5 occurring in the Euro-Mediterranean region. Waveform processing and database population are performed using the waveform processing module scwfparam, which is integrated in SeisComP3 (SC3; http://www.seiscomp3.org/). Earthquake information is provided by the EMSC (http://www.emsc-csem.org/) and all the seismic waveform data is accessed at the European Integrated waveform Data Archive (EIDA) at ORFEUS (http://www.orfeus-eu.org/index.html), where all on-scale data is used in the fully automated processing. As the EIDA community is continually growing, the already significant number of strong motion stations is also increasing and the importance of this product is expected to also increase. Real-time RRSM processing started in June 2014, while past events have been processed in order to provide a complete database back to 2005.

Using Tectonic Tremor to Constrain Seismic-wave Attenuation in Cascadia

NASA Astrophysics Data System (ADS)

Littel, G.; Thomas, A.; Baltay, A.

2017-12-01

In addition to fast, seismic slip, many subduction zones also host slow, largely aseismic slip, accompanied by a weak seismic signal known as tectonic tremor. Tremor is a small amplitude, low-frequency seismic signal that originates at the plate interface, down-dip of where large earthquakes typically occur. The Cascadia subduction zone has not seen a large megathrust earthquake since 1700, yet its recurrence interval of 350-500 years motivates heightened interest in understanding the seismic hazard of the region. Of great importance is to understand the degree to which waves are attenuated as they leave the plate interface and travel towards populated regions of interest. Ground motion prediction equations (GMPEs) relate ground motion to a number of parameters, including earthquake magnitude, depth, style of faulting, and anelastic attenuation, and are typically determined empirically from earthquake ground motion recordings. In Cascadia, however, earthquakes of the moderate size typically used to constrain GMPEs occur relatively infrequently compared to tectonic tremor events, which, in contrast, occur periodically approximately every 10-19 months. Studies have shown that the abundant tectonic tremor in Cascadia, despite its small amplitudes, can be used to constrain seismic wave attenuation in GMPEs. Here we quantify seismic wave attenuation and determine its spatial variations in Cascadia by performing an inversion using tremor ground motion amplitudes, taken as peak ground acceleration (PGA) and peak ground velocity (PGV) from 1 min window waveforms of each individual tremor event. We estimate the anelastic attenuation parameter for varying regional sections along the Cascadia margin. Changes in seismic-wave attenuation along the Cascadia Subduction Zone could result in significantly different ground motions in the event of a very large earthquake, hence quantifying attenuation may help to better estimate the severity of shaking in densely populated metropolitan areas such as Vancouver, Seattle and Portland.

Rotating columns: Relating structure-from-motion, accretion/deletion, and figure/ground

PubMed Central

Froyen, Vicky; Feldman, Jacob; Singh, Manish

2013-01-01

We present a novel phenomenon involving an interaction between accretion deletion, figure-ground interpretation, and structure-from-motion. Our displays contain alternating light and dark vertical regions in which random-dot textures moved horizontally at constant speed but in opposite directions in alternating regions. This motion is consistent with all the light regions in front, with the dark regions completing amodally into a single large surface moving in the background, or vice versa. Surprisingly, the regions that are perceived as figural are also perceived as 3-D volumes rotating in depth (like rotating columns)—despite the fact that dot motion is not consistent with 3-D rotation. In a series of experiments, we found we could manipulate which set of regions is perceived as rotating volumes simply by varying known geometric cues to figure ground, including convexity, parallelism, symmetry, and relative area. Subjects indicated which colored regions they perceived as rotating. For our displays we found convexity to be a stronger cue than either symmetry or parallelism. We furthermore found a smooth monotonic decay of the proportion by which subjects perceive symmetric regions as figural, as a function of their relative area. Our results reveal an intriguing new interaction between accretion-deletion, figure-ground, and 3-D motion that is not captured by existing models. They also provide an effective tool for measuring figure-ground perception. PMID:23946432

Rotating columns: relating structure-from-motion, accretion/deletion, and figure/ground.

PubMed

Froyen, Vicky; Feldman, Jacob; Singh, Manish

2013-08-14

We present a novel phenomenon involving an interaction between accretion deletion, figure-ground interpretation, and structure-from-motion. Our displays contain alternating light and dark vertical regions in which random-dot textures moved horizontally at constant speed but in opposite directions in alternating regions. This motion is consistent with all the light regions in front, with the dark regions completing amodally into a single large surface moving in the background, or vice versa. Surprisingly, the regions that are perceived as figural are also perceived as 3-D volumes rotating in depth (like rotating columns)-despite the fact that dot motion is not consistent with 3-D rotation. In a series of experiments, we found we could manipulate which set of regions is perceived as rotating volumes simply by varying known geometric cues to figure ground, including convexity, parallelism, symmetry, and relative area. Subjects indicated which colored regions they perceived as rotating. For our displays we found convexity to be a stronger cue than either symmetry or parallelism. We furthermore found a smooth monotonic decay of the proportion by which subjects perceive symmetric regions as figural, as a function of their relative area. Our results reveal an intriguing new interaction between accretion-deletion, figure-ground, and 3-D motion that is not captured by existing models. They also provide an effective tool for measuring figure-ground perception.

Low-Frequency Amplitudes Observed in a Set of the Strongest Recorded Ground Motions (Invited)

NASA Astrophysics Data System (ADS)

Anderson, J. G.; Koketsu, K.; Miyake, H.

2010-12-01

Anderson (2010) compiled a set of “exceptional” ground motion characterized by peak acceleration that exceeds 500 gal on at least one component or peak velocity that exceeds 50 cm/s on at least one component. With the addition of more recent data, there are now over 280 openly available records that meet these criteria. These data are examined to find to the empirical upper bound of observed pseudo-acceleration (PSA) response spectra and smoothed Fourier amplitude spectra. Statistics of amplitudes of PSA and of low-pass filtered acceleration and velocity have also been determined. Amplitudes recorded at the Kawaguchi-cho station (40 km) at 5-6 second period from the 1964 Niigata earthquake (Mw=8.3) are within ~20% of the current empirical limit of ground motions observed from all earthquakes in the data set including those from the near field. An even more impressive example is that amplitudes recorded at the SCT station (~300 km from the fault) with period of about 2 seconds, during the 1985 Michoacan, Mexico, earthquake (Mw=8.0), are about the same as the current empirical limit of ground motions observed from near field records. These examples support the idea that the hazard caused by long-period ground motions, amplified by basins and site conditions, is not sufficiently appreciated. Reference: Anderson, J. G. (2010), Bull. Seism. Soc. Am. 100, 1-36.

Design of Visco-Elastic Dampers for RC Frame for Site-Specific Earthquake

NASA Astrophysics Data System (ADS)

Kamatchi, P.; Rama Raju, K.; Ravisankar, K.; Iyer, Nagesh R.

2016-12-01

Number of Reinforced Concrete (RC) framed buildings have got damaged at Ahmedabad city, India located at about 240 km away from epicenter during January 2001, 7.6 moment magnitude (Mw) Bhuj earthquake. In the present study, two dimensional nonlinear time history dynamic analyses of a typical 13 storey frame assumed to be located at Ahmedabad is carried out with the rock level and surface level site-specific ground motion for scenario earthquake of Mw 7.6 from Bhuj. Artificial ground motions are generated using extended finite source stochastic model with seismological parameters reported in literature for 2001 Bhuj earthquake. Surface level ground motions are obtained for a typical soil profile of 100 m depth reported in literature through one dimensional equivalent linear wave propagation analyses. From the analyses, failure of frame is observed for surface level ground motions which indicates that, in addition to the in-adequacy of the cross sections and reinforcement of the RC members of the frame chosen, the rich energy content of the surface level ground motion near the fundamental time period of the frame has also contributed for the failure of frame. As a part of retrofitting measure, five Visco-elastic Dampers (VED) in chevron bracing are added to frame. For the frame considered in the present study, provision of VED is found to be effective to mitigate damage for the soil site considered.

Experimental evaluation of four ground-motion scaling methods for dynamic response-history analysis of nonlinear structures

USGS Publications Warehouse

O'Donnell, Andrew P.; Kurama, Yahya C.; Kalkan, Erol; Taflanidis, Alexandros A.

2017-01-01

This paper experimentally evaluates four methods to scale earthquake ground-motions within an ensemble of records to minimize the statistical dispersion and maximize the accuracy in the dynamic peak roof drift demand and peak inter-story drift demand estimates from response-history analyses of nonlinear building structures. The scaling methods that are investigated are based on: (1) ASCE/SEI 7–10 guidelines; (2) spectral acceleration at the fundamental (first mode) period of the structure, Sa(T1); (3) maximum incremental velocity, MIV; and (4) modal pushover analysis. A total of 720 shake-table tests of four small-scale nonlinear building frame specimens with different static and dynamic characteristics are conducted. The peak displacement demands from full suites of 36 near-fault ground-motion records as well as from smaller “unbiased” and “biased” design subsets (bins) of ground-motions are included. Out of the four scaling methods, ground-motions scaled to the median MIV of the ensemble resulted in the smallest dispersion in the peak roof and inter-story drift demands. Scaling based on MIValso provided the most accurate median demands as compared with the “benchmark” demands for structures with greater nonlinearity; however, this accuracy was reduced for structures exhibiting reduced nonlinearity. The modal pushover-based scaling (MPS) procedure was the only method to conservatively overestimate the median drift demands.

Comparison of flying qualities derived from in-flight and ground-based simulators for a jet-transport airplane for the approach and landing pilot tasks

NASA Technical Reports Server (NTRS)

Grantham, William D.

1989-01-01

The primary objective was to provide information to the flight controls/flying qualities engineer that will assist him in determining the incremental flying qualities and/or pilot-performance differences that may be expected between results obtained via ground-based simulation (and, in particular, the six-degree-of-freedom Langley Visual/Motion Simulator (VMS)) and flight tests. Pilot opinion and performance parameters derived from a ground-based simulator and an in-flight simulator are compared for a jet-transport airplane having 32 different longitudinal dynamic response characteristics. The primary pilot tasks were the approach and landing tasks with emphasis on the landing-flare task. The results indicate that, in general, flying qualities results obtained from the ground-based simulator may be considered conservative-especially when the pilot task requires tight pilot control as during the landing flare. The one exception to this, according to the present study, was that the pilots were more tolerant of large time delays in the airplane response on the ground-based simulator. The results also indicated that the ground-based simulator (particularly the Langley VMS) is not adequate for assessing pilot/vehicle performance capabilities (i.e., the sink rate performance for the landing-flare task when the pilot has little depth/height perception from the outside scene presentation).

Shear Wave Generation and Modeling Ground Motion From a Source Physics Experiment (SPE) Underground Explosion

NASA Astrophysics Data System (ADS)

Pitarka, Arben; Mellors, Robert; Rodgers, Arthur; Vorobiev, Oleg; Ezzedine, Souheil; Matzel, Eric; Ford, Sean; Walter, Bill; Antoun, Tarabay; Wagoner, Jeffery; Pasyanos, Mike; Petersson, Anders; Sjogreen, Bjorn

2014-05-01

We investigate the excitation and propagation of far-field (epicentral distance larger than 20 m) seismic waves by analyzing and modeling ground motion from an underground chemical explosion recorded during the Source Physics Experiment (SPE), Nevada. The far-field recorded ground motion is characterized by complex features, such as large azimuthal variations in P- and S-wave amplitudes, as well as substantial energy on the tangential component of motion. Shear wave energy is also observed on the tangential component of the near-field motion (epicentral distance smaller than 20 m) suggesting that shear waves were generated at or very near the source. These features become more pronounced as the waves propagate away from the source. We address the shear wave generation during the explosion by modeling ground motion waveforms recorded in the frequency range 0.01-20 Hz, at distances of up to 1 km. We used a physics based approach that combines hydrodynamic modeling of the source with anelastic modeling of wave propagation in order to separate the contributions from the source and near-source wave scattering on shear motion generation. We found that wave propagation scattering caused by the near-source geological environment, including surface topography, contributes to enhancement of shear waves generated from the explosion source. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-06NA25946/ NST11-NCNS-TM-EXP-PD15.

49 CFR 209.17 - Motions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... officer. Each motion shall state the particular order, ruling, or action desired and the grounds therefor... 49 Transportation 4 2011-10-01 2011-10-01 false Motions. 209.17 Section 209.17 Transportation... TRANSPORTATION RAILROAD SAFETY ENFORCEMENT PROCEDURES General § 209.17 Motions. Motions shall be in writing...

49 CFR 209.17 - Motions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... officer. Each motion shall state the particular order, ruling, or action desired and the grounds therefor... 49 Transportation 4 2010-10-01 2010-10-01 false Motions. 209.17 Section 209.17 Transportation... TRANSPORTATION RAILROAD SAFETY ENFORCEMENT PROCEDURES General § 209.17 Motions. Motions shall be in writing...

Autogenic feedback training experiment: A preventative method for space motion sickness

NASA Technical Reports Server (NTRS)

Cowings, Patricia S.

1993-01-01

Space motion sickness is a disorder which produces symptoms similar to those of motion sickness on Earth. This syndrome has affected approximately 50 percent of all astronauts and cosmonauts exposed to microgravity in space, but it differs from what is commonly known as motion sickness in a number of critical ways. There is currently no ground-based method for predicting susceptibility to motion sickness in space. Antimotion sickness drugs have had limited success in preventing or counteracting symptoms in space, and frequently caused debilitating side effects. The objectives were: (1) to evaluate the effectiveness of Autogenic-Feedback Training as a countermeasure for space motion sickness; (2) to compare physiological data and in-flight symptom reports to ground-based motion sickness data; and (3) to predict susceptibility to space motion sickness based on pre-flight data of each treatment group crew member.

Investigations in site response from ground motion observations in vertical arrays

NASA Astrophysics Data System (ADS)

Baise, Laurie Gaskins

The aim of the research is to improve the understanding of earthquake site response and to improve the techniques available to investigate issues in this field. Vertical array ground motion data paired with the empirical transfer function (ETF) methodology is shown to accurately characterize site response. This manuscript draws on methods developed in the field of signal processing and statistical time series analysis to parameterize the ETF as an autoregressive moving-average (ARMA) system which is justified theoretically, historically, and by example. Site response is evaluated at six sites in California, Japan, and Taiwan using ETF estimates, correlation analysis, and full waveform modeling. Correlation analysis is proposed as a required data quality evaluation imperative to any subsequent site response analysis. ETF estimates and waveform modeling are used to decipher the site response at sites with simple and complex geologic structure, which provide simple time-invariant and time-variant methods for evaluating both linear site transfer functions and nonlinear site response for sites experiencing liquefaction of the soils. The Treasure and Yerba Buena Island sites, however, require 2-D waveform modeling to accurately evaluate the effects of the shallow sedimentary basin. ETFs are used to characterize the Port Island site and corresponding shake table tests before, during, and after liquefaction. ETFs derived from the shake table tests were demonstrated to consistently predict the linear field ground response below 16 m depth and the liquefied behavior above 15 m depth. The liquefied interval response was demonstrated to gradually return to pre-liquefied conditions within several weeks of the 1995 Hyogo-ken Nanbu earthquake. Both the site's and the shake table test's response were shown to be effectively linear up to 0.5 g in the native materials below 16 m depth. The effective linearity of the site response at GVDA, Chiba, and Lotting up to 0.1 g, 0.33 g, and 0.49 g, respectively, further confirms that site response in the field may be more linear than expected from laboratory tests. Strong motions were predicted at these sites with normalized mean square error less than 0.10 using ETFs generated from weak motions. The Treasure Island site response was shown to be dominated by surface waves propagating in the shallow sediments of the San Francisco Bay. Low correlation of the ground motions recorded on rock at Yerba Buena Island and in rock beneath the Treasure Island site intimates that the Yerba Buena site is an inappropriate reference site for Treasure Island site response studies. Accurate simulation of the Treasure Island site response was achieved using a 2-D velocity structure comprised of a 100 m uniform soil basin (Vs = 400 m/s) over a weathered rock veneer (Vs = 1.5 km/s) to 200 m depth.

Ground motion values for use in the seismic design of the Trans-Alaska Pipeline system

USGS Publications Warehouse

Page, Robert A.; Boore, D.M.; Joyner, W.B.; Coulter, H.W.

1972-01-01

The proposed trans-Alaska oil pipeline, which would traverse the state north to south from Prudhoe Bay on the Arctic coast to Valdez on Prince William Sound, will be subject to serious earthquake hazards over much of its length. To be acceptable from an environmental standpoint, the pipeline system is to be designed to minimize the potential of oil leakage resulting from seismic shaking, faulting, and seismically induced ground deformation. The design of the pipeline system must accommodate the effects of earthquakes with magnitudes ranging from 5.5 to 8.5 as specified in the 'Stipulations for Proposed Trans-Alaskan Pipeline System.' This report characterizes ground motions for the specified earthquakes in terms of peak levels of ground acceleration, velocity, and displacement and of duration of shaking. Published strong motion data from the Western United States are critically reviewed to determine the intensity and duration of shaking within several kilometers of the slipped fault. For magnitudes 5 and 6, for which sufficient near-fault records are available, the adopted ground motion values are based on data. For larger earthquakes the values are based on extrapolations from the data for smaller shocks, guided by simplified theoretical models of the faulting process.

Ground-motion prediction equations for the average horizontal component of PGA, PGV, and 5%-damped PSA at spectral periods between 0.01 s and 10.0 s

USGS Publications Warehouse

Boore, D.M.; Atkinson, G.M.

2008-01-01

This paper contains ground-motion prediction equations (GMPEs) for average horizontal-component ground motions as a function of earthquake magnitude, distance from source to site, local average shear-wave velocity, and fault type. Our equations are for peak ground acceleration (PGA), peak ground velocity (PGV), and 5%-damped pseudo-absolute-acceleration spectra (PSA) at periods between 0.01 s and 10 s. They were derived by empirical regression of an extensive strong-motion database compiled by the 'PEER NGA' (Pacific Earthquake Engineering Research Center's Next Generation Attenuation) project. For periods less than 1 s, the analysis used 1,574 records from 58 mainshocks in the distance range from 0 km to 400 km (the number of available data decreased as period increased). The primary predictor variables are moment magnitude (M), closest horizontal distance to the surface projection of the fault plane (RJB), and the time-averaged shear-wave velocity from the surface to 30 m (VS30). The equations are applicable for M=5-8, RJB<200 km, and VS30= 180-1300 m/s. ?? 2008, Earthquake Engineering Research Institute.

High precision applications of the global positioning system

NASA Technical Reports Server (NTRS)

Lichten, Stephen M.

1991-01-01

The Global Positioning System (GPS) is a constellation of U.S. defense navigation satellites which can be used for military and civilian positioning applications. A wide variety of GPS scientific applications were identified and precise positioning capabilities with GPS were already demonstrated with data available from the present partial satellite constellation. Expected applications include: measurements of Earth crustal motion, particularly in seismically active regions; measurements of the Earth's rotation rate and pole orientation; high-precision Earth orbiter tracking; surveying; measurements of media propagation delays for calibration of deep space radiometric data in support of NASA planetary missions; determination of precise ground station coordinates; and precise time transfer worldwide.

Differences in attenuation among the stable continental regions

USGS Publications Warehouse

Bakun, W.H.; McGarr, A.

2002-01-01

There are systematic differences in the attenuation of damaging earthquake ground motions between different stable continental regions (SCRs). Seismic intensity and weak-motion data show that the attenuation in seismic waves for eastern North America (ENA) is less than for India, Africa, Australia, and northwest Europe. If ENA ground-motion attenuation relations are used in seismic hazard models for other SCRs, as is commonly done, then the estimated ground motions and resulting hazard may be too large. If an attenuation model that averages observations from ENA and the other SCRs is used to estimate the magnitudes of large historical earthquakes in ENA, as is the case for recent estimates of M for the 1811-1812 New Madrid, Missouri and the 1886 Charleston, South Carolina events, then the magnitude estimates for these events will be too large, as will be the resulting hazard.

Generation of Classical DInSAR and PSI Ground Motion Maps on a Cloud Thematic Platform

NASA Astrophysics Data System (ADS)

Mora, Oscar; Ordoqui, Patrick; Romero, Laia

2016-08-01

This paper presents the experience of ALTAMIRA INFORMATION uploading InSAR (Synthetic Aperture Radar Interferometry) services in the Geohazard Exploitation Platform (GEP), supported by ESA. Two different processing chains are presented jointly with ground motion maps obtained from the cloud computing, one being DIAPASON for classical DInSAR and SPN (Stable Point Network) for PSI (Persistent Scatterer Interferometry) processing. The product obtained from DIAPASON is the interferometric phase related to ground motion (phase fringes from a SAR pair). SPN provides motion data (mean velocity and time series) on high-quality pixels from a stack of SAR images. DIAPASON is already implemented, and SPN is under development to be exploited with historical data coming from ERS-1/2 and ENVISAT satellites, and current acquisitions of SENTINEL-1 in SLC and TOPSAR modes.

Attenuation of Outdoor Sound Propagation Levels by a Snow Cover

DTIC Science & Technology

1993-11-01

20 kN s m-4. Calculations of ground motion induced by the atmospheric sound waves were made using a viscoelastic model of the ground and the... Models of ground impedance. Past predictions of the material : effective flow resistivity a, porosity Q, acoustic pulse waveforms (Don and Cramond 1987...fibrous absorbent materials . Applied particle motion induced by a point source above a Acoustics, 3: 105-116. poroelastic half-space. Journal of the

Motion synthesis and force distribution analysis for a biped robot.

PubMed

Trojnacki, Maciej T; Zielińska, Teresa

2011-01-01

In this paper, the method of generating biped robot motion using recorded human gait is presented. The recorded data were modified taking into account the velocity available for robot drives. Data includes only selected joint angles, therefore the missing values were obtained considering the dynamic postural stability of the robot, which means obtaining an adequate motion trajectory of the so-called Zero Moment Point (ZMT). Also, the method of determining the ground reaction forces' distribution during the biped robot's dynamic stable walk is described. The method was developed by the authors. Following the description of equations characterizing the dynamics of robot's motion, the values of the components of ground reaction forces were symbolically determined as well as the coordinates of the points of robot's feet contact with the ground. The theoretical considerations have been supported by computer simulation and animation of the robot's motion. This was done using Matlab/Simulink package and Simulink 3D Animation Toolbox, and it has proved the proposed method.

SU-D-210-05: The Accuracy of Raw and B-Mode Image Data for Ultrasound Speckle Tracking in Radiation Therapy

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

O’Shea, T; Bamber, J; Harris, E

Purpose: For ultrasound speckle tracking there is some evidence that the envelope-detected signal (the main step in B-mode image formation) may be more accurate than raw ultrasound data for tracking larger inter-frame tissue motion. This study investigates the accuracy of raw radio-frequency (RF) versus non-logarithmic compressed envelope-detected (B-mode) data for ultrasound speckle tracking in the context of image-guided radiation therapy. Methods: Transperineal ultrasound RF data was acquired (with a 7.5 MHz linear transducer operating at a 12 Hz frame rate) from a speckle phantom moving with realistic intra-fraction prostate motion derived from a commercial tracking system. A normalised cross-correlation templatemore » matching algorithm was used to track speckle motion at the focus using (i) the RF signal and (ii) the B-mode signal. A range of imaging rates (0.5 to 12 Hz) were simulated by decimating the imaging sequences, therefore simulating larger to smaller inter-frame displacements. Motion estimation accuracy was quantified by comparison with known phantom motion. Results: The differences between RF and B-mode motion estimation accuracy (2D mean and 95% errors relative to ground truth displacements) were less than 0.01 mm for stable and persistent motion types and 0.2 mm for transient motion for imaging rates of 0.5 to 12 Hz. The mean correlation for all motion types and imaging rates was 0.851 and 0.845 for RF and B-mode data, respectively. Data type is expected to have most impact on axial (Superior-Inferior) motion estimation. Axial differences were <0.004 mm for stable and persistent motion and <0.3 mm for transient motion (axial mean errors were lowest for B-mode in all cases). Conclusions: Using the RF or B-mode signal for speckle motion estimation is comparable for translational prostate motion. B-mode image formation may involve other signal-processing steps which also influence motion estimation accuracy. A similar study for respiratory-induced motion would also be prudent. This work is support by Cancer Research UK Programme Grant C33589/A19727.« less

Strong Ground Motions Scenarios for Mexico City

NASA Astrophysics Data System (ADS)

Cabrera, E.; Chavez, M.; Madariaga, R.; Mai, P. M.; Frisenda, M.; Perea, N.

2005-12-01

The recordings available in Mexico City (MC) for extreme magnitude Subduction Superficial (SS), Subduction Deep (SD), and Crustal Superficial (CS) events are about 30 accelerograms (obtained at 10 sites) for the SS 19 09 1985 earthquake (Ms 8.1, Mw 8.01). In this work we generated broadband synthetic accelerograms expected in MC stiff (S) and compressive soils (C),for SS (Mw 8.5, 8.7), SD (Mw 7.6) and CS (Mw 7.5) earthquakes.The frequencies lower than 0.5 Hz were simulated by using a 4th order FD method, including a (fractal) finite-fault description of the sources. The frequencies larger than 0.5 Hz were modeled by the empirical Green function technique. We propose upper bounds of 0.4g and 2g (g=9.8m/s2)for the maximum response spectra acceleration(5 percent damping) expected in the S and C soils of MC, respectively.

Calibration Software for Use with Jurassicprok

NASA Technical Reports Server (NTRS)

Chapin, Elaine; Hensley, Scott; Siqueira, Paul

2004-01-01

The Jurassicprok Interferometric Calibration Software (also called "Calibration Processor" or simply "CP") estimates the calibration parameters of an airborne synthetic-aperture-radar (SAR) system, the raw measurement data of which are processed by the Jurassicprok software described in the preceding article. Calibration parameters estimated by CP include time delays, baseline offsets, phase screens, and radiometric offsets. CP examines raw radar-pulse data, single-look complex image data, and digital elevation map data. For each type of data, CP compares the actual values with values expected on the basis of ground-truth data. CP then converts the differences between the actual and expected values into updates for the calibration parameters in an interferometric calibration file (ICF) and a radiometric calibration file (RCF) for the particular SAR system. The updated ICF and RCF are used as inputs to both Jurassicprok and to the companion Motion Measurement Processor software (described in the following article) for use in generating calibrated digital elevation maps.

Uncertainty in Vs30-based site response

USGS Publications Warehouse

Thompson, Eric M.; Wald, David J.

2016-01-01

Methods that account for site response range in complexity from simple linear categorical adjustment factors to sophisticated nonlinear constitutive models. Seismic‐hazard analysis usually relies on ground‐motion prediction equations (GMPEs); within this framework site response is modeled statistically with simplified site parameters that include the time‐averaged shear‐wave velocity to 30 m (VS30) and basin depth parameters. Because VS30 is not known in most locations, it must be interpolated or inferred through secondary information such as geology or topography. In this article, we analyze a subset of stations for which VS30 has been measured to address effects of VS30 proxies on the uncertainty in the ground motions as modeled by GMPEs. The stations we analyze also include multiple recordings, which allow us to compute the repeatable site effects (or empirical amplification factors [EAFs]) from the ground motions. Although all methods exhibit similar bias, the proxy methods only reduce the ground‐motion standard deviations at long periods when compared to GMPEs without a site term, whereas measured VS30 values reduce the standard deviations at all periods. The standard deviation of the ground motions are much lower when the EAFs are used, indicating that future refinements of the site term in GMPEs have the potential to substantially reduce the overall uncertainty in the prediction of ground motions by GMPEs.

Rotational Seismology: AGU Session, Working Group, and Website

USGS Publications Warehouse

Lee, William H.K.; Igel, Heiner; Todorovska, Maria I.; Evans, John R.

2007-01-01

Introduction Although effects of rotational motions due to earthquakes have long been observed (e. g., Mallet, 1862), nevertheless Richter (1958, p. 213) stated that: 'Perfectly general motion would also involve rotations about three perpendicular axes, and three more instruments for these. Theory indicates, and observation confirms, that such rotations are negligible.' However, Richter provided no references for this claim. Seismology is based primarily on the observation and modeling of three-component translational ground motions. Nevertheless, theoretical seismologists (e.g., Aki and Richards, 1980, 2002) have argued for decades that the rotational part of ground motions should also be recorded. It is well known that standard seismometers are quite sensitive to rotations and therefore subject to rotation-induced errors. The paucity of observations of rotational motions is mainly the result of a lack, until recently, of affordable rotational sensors of sufficient resolution. Nevertheless, in the past decade, a number of authors have reported direct observations of rotational motions and rotations inferred from rigid-body rotations in short baseline accelerometer arrays, creating a burgeoning library of rotational data. For example, ring laser gyros in Germany and New Zealand have led to the first significant and consistent observations of rotational motions from distant earthquakes (Igel et al., 2005, 2007). A monograph on Earthquake Source Asymmetry, Structural Media and Rotation Effects was published recently as well by Teisseyre et al. (2006). Measurement of rotational motions has implications for: (1) recovering the complete ground-displacement history from seismometer recordings; (2) further constraining earthquake rupture properties; (3) extracting information about subsurface properties; and (4) providing additional ground motion information to earthquake engineers for seismic design. A special session on Rotational Motions in Seismology was convened by H. Igel, W.H.K. Lee, and M. Todorovska during the 2006 AGU Fall Meeting. The goal of this session was to discuss rotational sensors, observations, modeling, theoretical aspects, and potential applications of rotational ground motions. The session was accompanied by the inauguration of an International Working Group on Rotational Seismology (IWGoRS) which aims to promote investigations of all aspects of rotational motions in seismology and their implications for related fields such as earthquake engineering, geodesy, strong-motion seismology, and tectonics, as well as to share experience, data, software, and results in an open Web-based environment. The primary goal of this article is to make the Earth Science Community aware of the emergence of the field of rotational seismology.

Lower Extremity Movement Differences Persist After Anterior Cruciate Ligament Reconstruction and When Returning to Sports.

PubMed

Butler, Robert J; Dai, Boyi; Huffman, Nikki; Garrett, William E; Queen, Robin M

2016-09-01

To examine how landing mechanics change in patients after anterior cruciate ligament reconstruction (ACL-R) between 6 months and 12 months after surgery. Case-series. Laboratory. Fifteen adolescent patients after ACL-R participated. Lower extremity three-dimensional motion analysis was conducted during a bilateral stop jump task in patients at 6 and 12 months after ACL-R. Joint kinematic and kinetic data, in addition to ground reaction forces, were collected at each time point. During the stop jump landing, the peak joint moments and the initial and peak joint motion at the ankle, knee, and hip were examined. The peak vertical ground reaction force was also examined. Interactions were observed for both the peak knee (P = 0.03) and hip extension moment (P = 0.07). However, only the hip extension moment was symmetrical level at 12 months. Statistically significant (P < 0.05) side-to-side differences existed for the ankle angle at initial contact, peak plantarflexion moment, peak hip flexion angle, and peak impact vertical ground reaction force independent of time. The findings of this study suggest that sagittal plane moments at the knee and hip demonstrate an increase in symmetry between 6 months and 1 year after ACL-R surgery, however, symmetry of the knee extension moment is not established by 12 months after surgery. The lack of change in the variables across time was unexpected. As a result, it is inappropriate to expect a change in landing mechanics solely as a result of time alone after discharge from rehabilitation.

Prospective testing of neo-deterministic seismic hazard scenarios for the Italian territory

NASA Astrophysics Data System (ADS)

Peresan, Antonella; Magrin, Andrea; Vaccari, Franco; Kossobokov, Vladimir; Panza, Giuliano F.

2013-04-01

A reliable and comprehensive characterization of expected seismic ground shaking, eventually including the related time information, is essential in order to develop effective mitigation strategies and increase earthquake preparedness. Moreover, any effective tool for SHA must demonstrate its capability in anticipating the ground shaking related with large earthquake occurrences, a result that can be attained only through rigorous verification and validation process. So far, the major problems in classical probabilistic methods for seismic hazard assessment, PSHA, consisted in the adequate description of the earthquake recurrence, particularly for the largest and sporadic events, and of the attenuation models, which may be unable to account for the complexity of the medium and of the seismic sources and are often weekly constrained by the available observations. Current computational resources and physical knowledge of the seismic waves generation and propagation processes allow nowadays for viable numerical and analytical alternatives to the use of attenuation relations. Accordingly, a scenario-based neo-deterministic approach, NDSHA, to seismic hazard assessment has been proposed, which allows considering a wide range of possible seismic sources as the starting point for deriving scenarios by means of full waveforms modeling. The method does not make use of attenuation relations and naturally supplies realistic time series of ground shaking, including reliable estimates of ground displacement readily applicable to seismic isolation techniques. Based on NDSHA, an operational integrated procedure for seismic hazard assessment has been developed, that allows for the definition of time dependent scenarios of ground shaking, through the routine updating of formally defined earthquake predictions. The integrated NDSHA procedure for seismic input definition, which is currently applied to the Italian territory, combines different pattern recognition techniques, designed for the space-time identification of strong earthquakes, with algorithms for the realistic modeling of ground motion. Accordingly, a set of deterministic scenarios of ground motion at bedrock, which refers to the time interval when a strong event is likely to occur within the alerted area, can be defined by means of full waveform modeling, both at regional and local scale. CN and M8S predictions, as well as the related time-dependent ground motion scenarios associated with the alarmed areas, are regularly updated every two months since 2006. The routine application of the time-dependent NDSHA approach provides information that can be useful in assigning priorities for timely mitigation actions and, at the same time, allows for a rigorous prospective testing and validation of the proposed methodology. As an example, for sites where ground shaking values greater than 0.2 g are estimated at bedrock, further investigations can be performed taking into account the local soil conditions, to assess the performances of relevant structures, such as historical and strategic buildings. The issues related with prospective testing and validation of the time-dependent NDSHA scenarios will be discussed, illustrating the results obtained for the recent strong earthquakes in Italy, including the May 20, 2012 Emilia earthquake.

29 CFR 1921.5 - Motions and requests.

Code of Federal Regulations, 2011 CFR

2011-07-01

... motion or request shall state the particular order, ruling, or action desired, and the grounds therefor... 29 Labor 7 2011-07-01 2011-07-01 false Motions and requests. 1921.5 Section 1921.5 Labor... WORKERS' COMPENSATION ACT Prehearing Procedures § 1921.5 Motions and requests. Motions or requests shall...

24 CFR 26.16 - Motions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... a motion. All motions from the commencement of the action until the issuance of a decision shall be... written motions shall state the particular order, ruling, or action desired and the grounds for granting... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Motions. 26.16 Section 26.16...

19 CFR 210.15 - Motions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... action desired and the grounds therefor. (c) Responses to motions. Within 10 days after service of any... 19 Customs Duties 3 2010-04-01 2010-04-01 false Motions. 210.15 Section 210.15 Customs Duties... ADJUDICATION AND ENFORCEMENT Motions § 210.15 Motions. (a) Presentation and disposition. (1) During the period...

29 CFR 1921.5 - Motions and requests.

Code of Federal Regulations, 2010 CFR

2010-07-01

... motion or request shall state the particular order, ruling, or action desired, and the grounds therefor... 29 Labor 7 2010-07-01 2010-07-01 false Motions and requests. 1921.5 Section 1921.5 Labor... WORKERS' COMPENSATION ACT Prehearing Procedures § 1921.5 Motions and requests. Motions or requests shall...

19 CFR 210.15 - Motions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... action desired and the grounds therefor. (c) Responses to motions. Within 10 days after service of any... 19 Customs Duties 3 2011-04-01 2011-04-01 false Motions. 210.15 Section 210.15 Customs Duties... ADJUDICATION AND ENFORCEMENT Motions § 210.15 Motions. (a) Presentation and disposition. (1) During the period...

24 CFR 26.16 - Motions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... a motion. All motions from the commencement of the action until the issuance of a decision shall be... written motions shall state the particular order, ruling, or action desired and the grounds for granting... 24 Housing and Urban Development 1 2011-04-01 2011-04-01 false Motions. 26.16 Section 26.16...

Proceedings of Workshop XVI; The dynamic characteristics of faulting inferred from recordings of strong ground motion

USGS Publications Warehouse

Boatwright, John; Jacobson, Muriel L.

1982-01-01

The strong ground motions radiated by earthquake faulting are controlled by the dynamic characteristics of the faulting process. Although this assertion seems self-evident, seismologists have only recently begun to derive and test quantitative relations between common measures of strong ground motion and the dynamic characteristics of faulting. Interest in this problem has increased dramatically in past several years, however, resulting in a number of important advances. The research presented in this workshop is a significant part of this scientific development. Watching this development occur through the work of many scientists is exciting; to be able to gather a number of these scientists together in one workshop is a remarkable opportunity.

Real-time neural network earthquake profile predictor

DOEpatents

Leach, R.R.; Dowla, F.U.

1996-02-06

A neural network has been developed that uses first-arrival energy to predict the characteristics of impending earthquake seismograph signals. The propagation of ground motion energy through the earth is a highly nonlinear function. This is due to different forms of ground motion as well as to changes in the elastic properties of the media throughout the propagation path. The neural network is trained using seismogram data from earthquakes. Presented with a previously unseen earthquake, the neural network produces a profile of the complete earthquake signal using data from the first seconds of the signal. This offers a significant advance in the real-time monitoring, warning, and subsequent hazard minimization of catastrophic ground motion. 17 figs.

Real-time neural network earthquake profile predictor

DOEpatents

Leach, Richard R.; Dowla, Farid U.

1996-01-01

A neural network has been developed that uses first-arrival energy to predict the characteristics of impending earthquake seismograph signals. The propagation of ground motion energy through the earth is a highly nonlinear function. This is due to different forms of ground motion as well as to changes in the elastic properties of the media throughout the propagation path. The neural network is trained using seismogram data from earthquakes. Presented with a previously unseen earthquake, the neural network produces a profile of the complete earthquake signal using data from the first seconds of the signal. This offers a significant advance in the real-time monitoring, warning, and subsequent hazard minimization of catastrophic ground motion.

49 CFR 511.23 - Motions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... order, ruling, or action desired and the grounds therefor. If a motion is supported by memoranda... 49 Transportation 6 2011-10-01 2011-10-01 false Motions. 511.23 Section 511.23 Transportation..., DEPARTMENT OF TRANSPORTATION ADJUDICATIVE PROCEDURES Prehearing Procedures; Motions; Interlocutory Appeals...

49 CFR 511.23 - Motions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... order, ruling, or action desired and the grounds therefor. If a motion is supported by memoranda... 49 Transportation 6 2010-10-01 2010-10-01 false Motions. 511.23 Section 511.23 Transportation..., DEPARTMENT OF TRANSPORTATION ADJUDICATIVE PROCEDURES Prehearing Procedures; Motions; Interlocutory Appeals...

Broadband Ground Motion Observation and Simulation for the 2016 Kumamoto Earthquake

NASA Astrophysics Data System (ADS)

Miyake, H.; Chimoto, K.; Yamanaka, H.; Tsuno, S.; Korenaga, M.; Yamada, N.; Matsushima, T.; Miyakawa, K.

2016-12-01

During the 2016 Kumamoto earthquake, strong motion data were widely recorded by the permanent dense triggered strong motion network of K-NET/KiK-net and seismic intensity meters installed by local government and JMA. Seismic intensities close to the MMI 9-10 are recorded twice at the Mashiki town, and once at the Nishihara village and KiK-net Mashiki (KMMH16 ground surface). Near-fault records indicate extreme ground motion exceeding 400 cm/s in 5% pSv at a period of 1 s for the Mashiki town and 3-4 s for the Nishihara village. Fault parallel velocity components are larger between the Mashiki town and the Nishihara village, on the other hand, fault normal velocity components are larger inside the caldera of the Aso volcano. The former indicates rupture passed through along-strike stations, and the latter stations located at the forward rupture direction (e.g., Miyatake, 1999). In addition to the permanent observation, temporary continuous strong motion stations were installed just after the earthquake in the Kumamoto city, Mashiki town, Nishihara village, Minami-Aso village, and Aso town, (e.g., Chimoto et al., 2016; Tsuno et al., 2016; Yamanaka et al. 2016). This study performs to estimate strong motion generation areas for the 2016 Kumamoto earthquake sequence using the empirical Green's function method, then to simulate broadband ground motions for both the permanent and temporary strong motion stations. Currently the target period range is between 0.1 s to 5-10 s due to the signal-to-noise ratio of element earthquakes used for the empirical Green's functions. We also care fault dimension parameters N within 4 to 10 to avoid spectral sags and artificial periodicity. The simulated seismic intensities as well as fault normal and parallel velocity components will be discussed.

Advances in Pharmacotherapeutics of Space Motion Sickness

NASA Technical Reports Server (NTRS)

Putcha, Lakshmi

2006-01-01

Space Motion Sickness (SMS) is common occurrence in the U.S. manned space flight program and nearly 2/3 of Shuttle crewmembers experience SMS. Several drugs have been prescribed for therapeutic management of SMS. Typically, orally-administered SMS medications (scopolamine, promethazine) have poor bioavailability and often have detrimental neurocognitive side effects at recommended doses. Intramuscularly administered promethazine (PMZ) is perceived to have optimal efficacy with minimal side effects in space. However, intramuscular injections are painful and the sedating neurocognitive side effects of promethazine, significant in controlled ground testing, may be masked in orbit because injections are usually given prior to crew sleep. Currently, EVAs cannot be performed by symptomatic crew or prior to flight day three due to the lack of a consistently efficacious drug, concern about neurocognitive side effects, and because an in-suit vomiting episode is potentially fatal. NASA has long sought a fast acting, consistently effective anti-motion sickness medication which has only minor neurocognitive side effects. Development of intranasal formulations of scopolamine and promethazine, the two commonly used SMS drugs at NASA for both space and reduced gravity environment medical operations, appears to be a logical alternative to current treatment modalities for SMS. The advantages are expected to be fast absorption, reliable and high bioavailability, and probably reduced neurocognitive side effects owing to dose reduction. Results from clinical trials with intranasal scopolamine gel formulation and pre-clinical testing of a prototype microcapsule intranasal gel dosage form of PMZ (INPMZ) will be discussed. These formulations are expected to offer a dependable and effective noninvasive treatment option for SMS.

Strong motion simulation by the composite source modeling: A case study of 1679 M8.0 Sanhe-Pinggu earthquake

NASA Astrophysics Data System (ADS)

Liu, Bo-Yan; Shi, Bao-Ping; Zhang, Jian

2007-05-01

In this study, a composite source model has been used to calculate the realistic strong ground motions in Beijing area, caused by 1679 M S8.0 earthquake in Sanhe-Pinggu. The results could provide us the useful physical parameters for the future seismic hazard analysis in this area. Considering the regional geological/geophysical background, we simulated the scenario earthquake with an associated ground motions in the area ranging from 39.3°N to 41.1°N in latitude and from 115.35°E to 117.55°E in longitude. Some of the key factors which could influence the characteristics of strong ground motion have been discussed, and the resultant peak ground acceleration (PGA) distribution and the peak ground velocity (PGV) distribution around Beijing area also have been made as well. A comparison of the simulated result with the results derived from the attenuation relation has been made, and a sufficient discussion about the advantages and disadvantages of composite source model also has been given in this study. The numerical results, such as the PGA, PGV, peak ground displacement (PGD), and the three-component time-histories developed for Beijing area, have a potential application in earthquake engineering field and building code design, especially for the evaluation of critical constructions, government decision making and the seismic hazard assessment by financial/insurance companies.

Quantum mechanics in rotating-radio-frequency traps and Penning traps with a quadrupole rotating field

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

Abe, K.; Hasegawa, T.

2010-03-15

Quantum-mechanical analysis of ion motion in a rotating-radio-frequency (rrf) trap or in a Penning trap with a quadrupole rotating field is carried out. Rrf traps were introduced by Hasegawa and Bollinger [Phys. Rev. A 72, 043404 (2005)]. The classical motion of a single ion in this trap is described by only trigonometric functions, whereas in the conventional linear radio-frequency (rf) traps it is by the Mathieu functions. Because of the simple classical motion in the rrf trap, it is expected that the quantum-mechanical analysis of the rrf traps is also simple compared to that of the linear rf traps. Themore » analysis of Penning traps with a quadrupole rotating field is also possible in a way similar to the rrf traps. As a result, the Hamiltonian in these traps is the same as the two-dimensional harmonic oscillator, and energy levels and wave functions are derived as exact results. In these traps, it is found that one of the vibrational modes in the rotating frame can have negative energy levels, which means that the zero-quantum-number state (''ground'' state) is the highest energy state.« less

Analysis of exceptionally large tremors in two gold mining districts of South Africa

USGS Publications Warehouse

McGarr, A.; Bicknell, J.; Sembera, E.; Green, R.W.E.

1989-01-01

An investigation of ground motion, recorded using broad-band, wide dynamic-range digital seismographs, of large mine tremors from two South African mining districts with different geologic settings, reveals some essential differences in both seismic source and ground motion parameters. In the Klerksdorp district where the strata are offset by major throughgoing normal faults, the largest tremors, with magnitudes ranging as high as 5.2, tend to be associated with slip on these pre-existing faults. Moreover, the seismic source and ground motion parameters are quite similar to those of natural crustal earthquakes. In the Carletonville district, by contrast, where substantial faults do not exist, the large-magnitude tremors appear to result from the failure of relatively intact rock and cause seismic stress drops and ground motion parameters higher than normally observed for natural shocks. Additionally, there appears to be an upper magnitude limit of about 4 in the Carletonville district. Detailed analyses of an exceptionally large event recorded locally from each of these districts serve to highlight these contrasts. ?? 1989 Birkha??user Verlag.

Automatic generation of smart earthquake-resistant building system: Hybrid system of base-isolation and building-connection.

PubMed

Kasagi, M; Fujita, K; Tsuji, M; Takewaki, I

2016-02-01

A base-isolated building may sometimes exhibit an undesirable large response to a long-duration, long-period earthquake ground motion and a connected building system without base-isolation may show a large response to a near-fault (rather high-frequency) earthquake ground motion. To overcome both deficiencies, a new hybrid control system of base-isolation and building-connection is proposed and investigated. In this new hybrid building system, a base-isolated building is connected to a stiffer free wall with oil dampers. It has been demonstrated in a preliminary research that the proposed hybrid system is effective both for near-fault (rather high-frequency) and long-duration, long-period earthquake ground motions and has sufficient redundancy and robustness for a broad range of earthquake ground motions.An automatic generation algorithm of this kind of smart structures of base-isolation and building-connection hybrid systems is presented in this paper. It is shown that, while the proposed algorithm does not work well in a building without the connecting-damper system, it works well in the proposed smart hybrid system with the connecting damper system.

Toward Exascale Earthquake Ground Motion Simulations for Near-Fault Engineering Analysis

DOE PAGES

Johansen, Hans; Rodgers, Arthur; Petersson, N. Anders; ...

2017-09-01

Modernizing SW4 for massively parallel time-domain simulations of earthquake ground motions in 3D earth models increases resolution and provides ground motion estimates for critical infrastructure risk evaluations. Simulations of ground motions from large (M ≥ 7.0) earthquakes require domains on the order of 100 to500 km and spatial granularity on the order of 1 to5 m resulting in hundreds of billions of grid points. Surface-focused structured mesh refinement (SMR) allows for more constant grid point per wavelength scaling in typical Earth models, where wavespeeds increase with depth. In fact, MR allows for simulations to double the frequency content relative tomore » a fixed grid calculation on a given resource. The authors report improvements to the SW4 algorithm developed while porting the code to the Cori Phase 2 (Intel Xeon Phi) systems at the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. As a result, investigations of the performance of the innermost loop of the calculations found that reorganizing the order of operations can improve performance for massive problems.« less

Toward Exascale Earthquake Ground Motion Simulations for Near-Fault Engineering Analysis

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

Johansen, Hans; Rodgers, Arthur; Petersson, N. Anders

Modernizing SW4 for massively parallel time-domain simulations of earthquake ground motions in 3D earth models increases resolution and provides ground motion estimates for critical infrastructure risk evaluations. Simulations of ground motions from large (M ≥ 7.0) earthquakes require domains on the order of 100 to500 km and spatial granularity on the order of 1 to5 m resulting in hundreds of billions of grid points. Surface-focused structured mesh refinement (SMR) allows for more constant grid point per wavelength scaling in typical Earth models, where wavespeeds increase with depth. In fact, MR allows for simulations to double the frequency content relative tomore » a fixed grid calculation on a given resource. The authors report improvements to the SW4 algorithm developed while porting the code to the Cori Phase 2 (Intel Xeon Phi) systems at the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. As a result, investigations of the performance of the innermost loop of the calculations found that reorganizing the order of operations can improve performance for massive problems.« less

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.

Refinements to the Graves and Pitarka (2010) Broadband Ground-Motion Simulation Method

DOE PAGES

Graves, Robert; Pitarka, Arben

2014-12-17

This brief article describes refinements to the Graves and Pitarka (2010) broadband ground-motion simulation methodology (GP2010 hereafter) that have been implemented in version 14.3 of the Southern California Earthquake Center (SCEC) Broadband Platform (BBP). The updated version of our method on the current SCEC BBP is referred to as GP14.3. Here, our simulation technique is a hybrid approach that combines low- and high-frequency motions computed with different methods into a single broadband response.

Conceptual Research of Lunar-based Earth Observation for Polar Glacier Motion

NASA Astrophysics Data System (ADS)

Ruan, Zhixing; Liu, Guang; Ding, Yixing

2016-07-01

The ice flow velocity of glaciers is important for estimating the polar ice sheet mass balance, and it is of great significance for studies into rising sea level under the background of global warming. However so far the long-term and global measurements of these macro-scale motion processes of the polar glaciers have hardly been achieved by Earth Observation (EO) technique from the ground, aircraft or satellites in space. This paper, facing the demand for space technology for large-scale global environmental change observation,especially the changes of polar glaciers, and proposes a new concept involving setting up sensors on the lunar surface and using the Moon as a platform for Earth observation, transmitting the data back to Earth. Lunar-based Earth observation, which enables the Earth's large-scale, continuous, long-term dynamic motions to be measured, is expected to provide a new solution to the problems mentioned above. According to the pattern and characteristics of polar glaciers motion, we will propose a comprehensive investigation of Lunar-based Earth observation with synthetic aperture radar (SAR). Via theoretical modeling and experimental simulation inversion, intensive studies of Lunar-based Earth observation for the glacier motions in the polar regions will be implemented, including the InSAR basics theory, observation modes of InSAR and optimization methods of their key parameters. It will be of a great help to creatively expand the EO technique system from space. In addition, they will contribute to establishing the theoretical foundation for the realization of the global, long-term and continuous observation for the glacier motion phenomena in the Antarctic and the Arctic.

Towards Coupling of Macroseismic Intensity with Structural Damage Indicators

NASA Astrophysics Data System (ADS)

Kouteva, Mihaela; Boshnakov, Krasimir

2016-04-01

Knowledge on basic data of ground motion acceleration time histories during earthquakes is essential to understanding the earthquake resistant behaviour of structures. Peak and integral ground motion parameters such as peak ground motion values (acceleration, velocity and displacement), measures of the frequency content of ground motion, duration of strong shaking and various intensity measures play important roles in seismic evaluation of existing facilities and design of new systems. Macroseismic intensity is an earthquake measure related to seismic hazard and seismic risk description. Having detailed ideas on the correlations between the earthquake damage potential and macroseismic intensity is an important issue in engineering seismology and earthquake engineering. Reliable earthquake hazard estimation is the major prerequisite to successful disaster risk management. The usage of advanced earthquake engineering approaches for structural response modelling is essential for reliable evaluation of the accumulated damages in the existing buildings and structures due to the history of seismic actions, occurred during their lifetime. Full nonlinear analysis taking into account single event or series of earthquakes and the large set of elaborated damage indices are suitable contemporary tools to cope with this responsible task. This paper presents some results on the correlation between observational damage states, ground motion parameters and selected analytical damage indices. Damage indices are computed on the base of nonlinear time history analysis of test reinforced structure, characterising the building stock of the Mediterranean region designed according the earthquake resistant requirements in mid XX-th century.

Three-dimensional long-period groundmotion simulations in the upper Mississippi embayment

USGS Publications Warehouse

Macpherson, K.A.; Woolery, E.W.; Wang, Z.; Liu, P.

2010-01-01

We employed a 3D velocity model and 3D wave propagation code to simulate long-period ground motions in the upper Mississippi embayment. This region is at risk from large earthquakes in the New Madrid seismic zone (NMSZ) and observational data are sparse, making simulation a valuable tool for predicting the effects of large events. We undertook these simulations to estimate the magnitude of shaking likely to occur and to investigate the influence of the 3D embayment structure and finite-fault mechanics on ground motions. There exist three primary fault zones in the NMSZ, each of which was likely associated with one of the main shocks of the 1811-12 earthquake triplet. For this study, three simulations have been conducted on each major segment, exploring the impact of different epicentral locations and rupture directions on ground motions. The full wave field up to a frequency of 0.5 Hz is computed on a 200 ?? 200 ?? 50-km 3 volume using a staggered-grid finite-difference code. Peak horizontal velocity and bracketed durations were calculated at the free surface. The NMSZ simulations indicate that for the considered bandwidth, finite-fault mechanics such as fault proximity, directivity effect, and slip distribution exert the most control on ground motions. The 3D geologic structure of the upper Mississippi embayment also influences ground motion with indications that amplification is induced by the sharp velocity contrast at the basin edge.

Simulation of broadband ground motion including nonlinear soil effects for a magnitude 6.5 earthquake on the Seattle fault, Seattle, Washington

USGS Publications Warehouse

Hartzell, S.; Leeds, A.; Frankel, A.; Williams, R.A.; Odum, J.; Stephenson, W.; Silva, W.

2002-01-01

The Seattle fault poses a significant seismic hazard to the city of Seattle, Washington. A hybrid, low-frequency, high-frequency method is used to calculate broadband (0-20 Hz) ground-motion time histories for a M 6.5 earthquake on the Seattle fault. Low frequencies (1 Hz) are calculated by a stochastic method that uses a fractal subevent size distribution to give an ω-2 displacement spectrum. Time histories are calculated for a grid of stations and then corrected for the local site response using a classification scheme based on the surficial geology. Average shear-wave velocity profiles are developed for six surficial geologic units: artificial fill, modified land, Esperance sand, Lawton clay, till, and Tertiary sandstone. These profiles together with other soil parameters are used to compare linear, equivalent-linear, and nonlinear predictions of ground motion in the frequency band 0-15 Hz. Linear site-response corrections are found to yield unreasonably large ground motions. Equivalent-linear and nonlinear calculations give peak values similar to the 1994 Northridge, California, earthquake and those predicted by regression relationships. Ground-motion variance is estimated for (1) randomization of the velocity profiles, (2) variation in source parameters, and (3) choice of nonlinear model. Within the limits of the models tested, the results are found to be most sensitive to the nonlinear model and soil parameters, notably the over consolidation ratio.

Imprint of Rupture Directivity From Ground Motions of the 24 August 2016 Mw6.2 Central Italy Earthquake

NASA Astrophysics Data System (ADS)

Ren, Yefei; Wang, Hongwei; Wen, Ruizhi

2017-12-01

An Mw6.2 earthquake occurred in Central Italy on 24 August 2016. The objective of this study was to reveal the imprint of rupture directivity using the strong motion recordings. The strong motion stations were separated into two groups: southeast (SE) and northwest (NW). The effects of rupture directivity on the peak ground acceleration (PGA), peak ground velocity (PGV), and pseudo spectral acceleration (PSA) were investigated. The observed values of these parameters were compared with predicted values derived from ground motion prediction equations. The results showed that the residuals between the observed and predicted PGAs, PGVs, and PSAs at periods of T < 1 s were correlated significantly with azimuth angle and generally larger in the NW sector, reflecting that the observed PGAs, PGVs, and short-period PSAs in the NW sector were generally larger than observed in the SE sector. These phenomena are accordant with the theoretical law that the rupture directivity causes higher amplitudes in the forward direction compared with the backward direction. Finally, selected source rupture parameters were inverted using PGAs and PGVs. This revealed that the rupture was predominantly unilateral rupture, the major rupture was likely at an azimuth of 360°, and the length of the major rupture was proportional to 70%-100% of the total ruptured fault, confirming that rupture directivity caused the differences in the ground motions observed in the SE and NW sectors.

Conditional spectrum computation incorporating multiple causal earthquakes and ground-motion prediction models

USGS Publications Warehouse

Lin, Ting; Harmsen, Stephen C.; Baker, Jack W.; Luco, Nicolas

2013-01-01

The conditional spectrum (CS) is a target spectrum (with conditional mean and conditional standard deviation) that links seismic hazard information with ground-motion selection for nonlinear dynamic analysis. Probabilistic seismic hazard analysis (PSHA) estimates the ground-motion hazard by incorporating the aleatory uncertainties in all earthquake scenarios and resulting ground motions, as well as the epistemic uncertainties in ground-motion prediction models (GMPMs) and seismic source models. Typical CS calculations to date are produced for a single earthquake scenario using a single GMPM, but more precise use requires consideration of at least multiple causal earthquakes and multiple GMPMs that are often considered in a PSHA computation. This paper presents the mathematics underlying these more precise CS calculations. Despite requiring more effort to compute than approximate calculations using a single causal earthquake and GMPM, the proposed approach produces an exact output that has a theoretical basis. To demonstrate the results of this approach and compare the exact and approximate calculations, several example calculations are performed for real sites in the western United States. The results also provide some insights regarding the circumstances under which approximate results are likely to closely match more exact results. To facilitate these more precise calculations for real applications, the exact CS calculations can now be performed for real sites in the United States using new deaggregation features in the U.S. Geological Survey hazard mapping tools. Details regarding this implementation are discussed in this paper.

Calculation of broadband time histories of ground motion: Comparison of methods and validation using strong-ground motion from the 1994 Northridge earthquake

USGS Publications Warehouse

Hartzell, S.; Harmsen, S.; Frankel, A.; Larsen, S.

1999-01-01

This article compares techniques for calculating broadband time histories of ground motion in the near field of a finite fault by comparing synthetics with the strong-motion data set for the 1994 Northridge earthquake. Based on this comparison, a preferred methodology is presented. Ground-motion-simulation techniques are divided into two general methods: kinematic- and composite-fault models. Green's functions of three types are evaluated: stochastic, empirical, and theoretical. A hybrid scheme is found to give the best fit to the Northridge data. Low frequencies ( 1 Hz) are calculated using a composite-fault model with a fractal subevent size distribution and stochastic, bandlimited, white-noise Green's functions. At frequencies below 1 Hz, theoretical elastic-wave-propagation synthetics introduce proper seismic-phase arrivals of body waves and surface waves. The 3D velocity structure more accurately reproduces record durations for the deep sedimentary basin structures found in the Los Angeles region. At frequencies above 1 Hz, scattering effects become important and wave propagation is more accurately represented by stochastic Green's functions. A fractal subevent size distribution for the composite fault model ensures an ??-2 spectral shape over the entire frequency band considered (0.1-20 Hz).

Implications of next generation attenuation ground motion prediction equations for site coefficients used in earthquake resistant design

USGS Publications Warehouse

Borcherdt, Roger D.

2014-01-01

Proposals are developed to update Tables 11.4-1 and 11.4-2 of Minimum Design Loads for Buildings and Other Structures published as American Society of Civil Engineers Structural Engineering Institute standard 7-10 (ASCE/SEI 7–10). The updates are mean next generation attenuation (NGA) site coefficients inferred directly from the four NGA ground motion prediction equations used to derive the maximum considered earthquake response maps adopted in ASCE/SEI 7–10. Proposals include the recommendation to use straight-line interpolation to infer site coefficients at intermediate values of (average shear velocity to 30-m depth). The NGA coefficients are shown to agree well with adopted site coefficients at low levels of input motion (0.1 g) and those observed from the Loma Prieta earthquake. For higher levels of input motion, the majority of the adopted values are within the 95% epistemic-uncertainty limits implied by the NGA estimates with the exceptions being the mid-period site coefficient, Fv, for site class D and the short-period coefficient, Fa, for site class C, both of which are slightly less than the corresponding 95% limit. The NGA data base shows that the median value  of 913 m/s for site class B is more typical than 760 m/s as a value to characterize firm to hard rock sites as the uniform ground condition for future maximum considered earthquake response ground motion estimates. Future updates of NGA ground motion prediction equations can be incorporated easily into future adjustments of adopted site coefficients using procedures presented herein. 

A study of Guptkashi, Uttarakhand earthquake of 6 February 2017 ( M w 5.3) in the Himalayan arc and implications for ground motion estimation

NASA Astrophysics Data System (ADS)

Srinagesh, Davuluri; Singh, Shri Krishna; Suresh, Gaddale; Srinivas, Dakuri; Pérez-Campos, Xyoli; Suresh, Gudapati

2018-05-01

The 2017 Guptkashi earthquake occurred in a segment of the Himalayan arc with high potential for a strong earthquake in the near future. In this context, a careful analysis of the earthquake is important as it may shed light on source and ground motion characteristics during future earthquakes. Using the earthquake recording on a single broadband strong-motion seismograph installed at the epicenter, we estimate the earthquake's location (30.546° N, 79.063° E), depth ( H = 19 km), the seismic moment ( M 0 = 1.12×1017 Nm, M w 5.3), the focal mechanism ( φ = 280°, δ = 14°, λ = 84°), the source radius ( a = 1.3 km), and the static stress drop (Δ σ s 22 MPa). The event occurred just above the Main Himalayan Thrust. S-wave spectra of the earthquake at hard sites in the arc are well approximated (assuming ω -2 source model) by attenuation parameters Q( f) = 500 f 0.9, κ = 0.04 s, and f max = infinite, and a stress drop of Δ σ = 70 MPa. Observed and computed peak ground motions, using stochastic method along with parameters inferred from spectral analysis, agree well with each other. These attenuation parameters are also reasonable for the observed spectra and/or peak ground motion parameters in the arc at distances ≤ 200 km during five other earthquakes in the region (4.6 ≤ M w ≤ 6.9). The estimated stress drop of the six events ranges from 20 to 120 MPa. Our analysis suggests that attenuation parameters given above may be used for ground motion estimation at hard sites in the Himalayan arc via the stochastic method.

Earthquake Ground Motion Simulations in the Central United States

NASA Astrophysics Data System (ADS)

Ramirez Guzman, L.; Boyd, O. S.; Hartzell, S.; Williams, R. A.

2010-12-01

The Central United States (CUS) includes two of the major seismic zones east of the Rockies: the New Madrid and Wabash Valley Seismic Zones. The winter 1811-1812 New Madrid Seismic Zone (NMSZ) events were the largest intraplate sequence ever recorded in the United States. Together with their aftershocks, these earthquakes produced large areas of liquefaction, new lakes, and landslides in the region. Seismicity in the early 1800’s was dominated by the NMSZ activity, although three low magnitude 5 earthquakes occurred in the last 40 years in the Wabash Valley Seismic Zone (WVSZ). The population and infrastructure of the CUS have drastically changed from that of the early nineteenth century, and a large earthquake would now cause significant casualties and economic losses within the country’s heartland. In this study we present three sets of numerical simulations depicting earthquakes in the region. These hypothetical ruptures are located on the Reelfoot fault and the southern axial arm of the NMSZ and in the WVSZ. Our broad-band synthetic ground motions are calculated following the Liu et al. (2006) hybrid method. Using a finite element solver we calculate low frequency ground motion (< 1 Hz) which accounts for the heterogeneity and low velocity soils of the region by using a recently developed seismic velocity model (CUSVM1) and a minimum shear wave velocity of 300 m/s. The broad-band ground motions are then generated by combining high frequency synthetics computed in a 1D velocity model with the low frequency motions at a crossover frequency of 1 Hz. We primarily discuss the basin effects produced by the Mississippi embayment and investigate the effects of hypocentral location and slip distribution on ground motions in densely populated areas within the CUS.

A study of Guptkashi, Uttarakhand earthquake of 6 February 2017 (M w 5.3) in the Himalayan arc and implications for ground motion estimation

NASA Astrophysics Data System (ADS)

Srinagesh, Davuluri; Singh, Shri Krishna; Suresh, Gaddale; Srinivas, Dakuri; Pérez-Campos, Xyoli; Suresh, Gudapati

2018-02-01

The 2017 Guptkashi earthquake occurred in a segment of the Himalayan arc with high potential for a strong earthquake in the near future. In this context, a careful analysis of the earthquake is important as it may shed light on source and ground motion characteristics during future earthquakes. Using the earthquake recording on a single broadband strong-motion seismograph installed at the epicenter, we estimate the earthquake's location (30.546° N, 79.063° E), depth (H = 19 km), the seismic moment (M 0 = 1.12×1017 Nm, M w 5.3), the focal mechanism (φ = 280°, δ = 14°, λ = 84°), the source radius (a = 1.3 km), and the static stress drop (Δσ s 22 MPa). The event occurred just above the Main Himalayan Thrust. S-wave spectra of the earthquake at hard sites in the arc are well approximated (assuming ω -2 source model) by attenuation parameters Q(f) = 500f 0.9, κ = 0.04 s, and f max = infinite, and a stress drop of Δσ = 70 MPa. Observed and computed peak ground motions, using stochastic method along with parameters inferred from spectral analysis, agree well with each other. These attenuation parameters are also reasonable for the observed spectra and/or peak ground motion parameters in the arc at distances ≤ 200 km during five other earthquakes in the region (4.6 ≤ M w ≤ 6.9). The estimated stress drop of the six events ranges from 20 to 120 MPa. Our analysis suggests that attenuation parameters given above may be used for ground motion estimation at hard sites in the Himalayan arc via the stochastic method.

Strong motion from surface waves in deep sedimentary basins

USGS Publications Warehouse

Joyner, W.B.

2000-01-01

It is widely recognized that long-period surface waves generated by conversion of body waves at the boundaries of deep sedimentary basins make an important contribution to strong ground motion. The factors controlling the amplitude of such motion, however, are not widely understood. A study of pseudovelocity response spectra of strong-motion records from the Los Angeles Basin shows that late-arriving surface waves with group velocities of about 1 km/sec dominate the ground motion for periods of 3 sec and longer. The rate of amplitude decay for these waves is less than for the body waves and depends significantly on period, with smaller decay for longer periods. The amplitude can be modeled by the equation log y = f(M, RE) + c + bRB where y is the pseudovelocity response, f(M, RE) is an attenuation relation based on a general strong-motion data set, M is moment magnitude, RE is the distance from the source to the edge of the basin, RB is the distance from the edge of the basin to the recording site, and b and c are parameters fit to the data. The equation gives values larger by as much as a factor of 3 than given by the attenuation relationships based on general strong-motion data sets for the same source-site distance. It is clear that surface waves need to be taken into account in the design of long-period structures in deep sedimentary basins. The ground-motion levels specified by the earthquake provisions of current building codes, in California at least, accommodate the long-period ground motions from basin-edge-generated surface waves for periods of 5 sec and less and earthquakes with moment magnitudes of 7.5 or less located more than 20 km outside the basin. There may be problems at longer periods and for earthquakes located closer to the basin edge. The results of this study suggest that anelastic attenuation may need to be included in attempts to model long-period motion in deep sedimentary basins. To obtain better data on surface waves in the future, operators of strong-motion networks should take special care for the faithful recording of the long-period components of ground motion. It will also be necessary to insure that at least some selected recorders, once triggered, continue to operate for a time sufficient for the surface waves to traverse the basin. With velocities of about 1 km/sec, that time will be as long as 100 sec for a basin the size of the Los Angeles Basin.

Seismic response of Pacific Park Plaza. I. Data and preliminary analysis

USGS Publications Warehouse

Celebi, M.; Safak, E.

1992-01-01

The objective of this paper is to present analyses of a set of acceleration response records obtained during the October 17, 1989 Loma Prieta earthquake (Ms = 7.1) from the 30-story, three-winged, ductile moment-resistant reinforced-concrete-framed Pacific Park Plaza Building, located in Emeryville, east of San Francisco, Calif. The building was constructed in 1983, and instrumented in 1985 with 21 channels of synchronized uniaxial accelerometers deployed throughout the structure, and three channels of accelerometers located at free-field outside on the north side of the building, all connected to a central recording system. In addition, a triaxial strong-motion accelerograph is deployed at free-field on the south side of the building. The predominant response modes of the building and the associated frequencies at approximately 0.4 Hz and 1.0 Hz are identified visually from the unprocessed records, and also from Fourier amplitude spectra of the processed records, which, as expected, reveal significant torsional motion. In addition, the response spectra of the free-field and basement motions are very similar. These spectra show that significant structural resonances at higher modes influence both the ground level and the free-field motions, thus rising the question as to the definition of free-field motion, at least at this site. This part of the paper includes the preliminary analyses of the data acquired from this building. Part 2 of the paper provides detailed analyses of the data using system identification techniques.

Validation of Broadband Ground Motion Simulations for Japanese Crustal Earthquakes by the Recipe

NASA Astrophysics Data System (ADS)

Iwaki, A.; Maeda, T.; Morikawa, N.; Miyake, H.; Fujiwara, H.

2015-12-01

The Headquarters for Earthquake Research Promotion (HERP) of Japan has organized the broadband ground motion simulation method into a standard procedure called the "recipe" (HERP, 2009). In the recipe, the source rupture is represented by the characterized source model (Irikura and Miyake, 2011). The broadband ground motion time histories are computed by a hybrid approach: the 3-D finite-difference method (Aoi et al. 2004) and the stochastic Green's function method (Dan and Sato, 1998; Dan et al. 2000) for the long- (> 1　s) and short-period (< 1 s) components, respectively, using the 3-D velocity structure model. As the engineering significance of scenario earthquake ground motion prediction is increasing, thorough verification and validation are required for the simulation methods. This study presents the self-validation of the recipe for two MW6.6 crustal events in Japan, the 2000 Tottori and 2004 Chuetsu (Niigata) earthquakes. We first compare the simulated velocity time series with the observation. Main features of the velocity waveforms, such as the near-fault pulses and the large later phases on deep sediment sites are well reproduced by the simulations. Then we evaluate 5% damped pseudo acceleration spectra (PSA) in the framework of the SCEC Broadband Platform (BBP) validation (Dreger et al. 2015). The validation results are generally acceptable in the period range 0.1 - 10 s, whereas those in the shortest period range (0.01-0.1 s) are less satisfactory. We also evaluate the simulations with the 1-D velocity structure models used in the SCEC BBP validation exercise. Although the goodness-of-fit parameters for PSA do not significantly differ from those for the 3-D velocity structure model, noticeable differences in velocity waveforms are observed. Our results suggest the importance of 1) well-constrained 3-D velocity structure model for broadband ground motion simulations and 2) evaluation of time series of ground motion as well as response spectra.

Simulated ground motion in Santa Clara Valley, California, and vicinity from M≥6.7 scenario earthquakes

USGS Publications Warehouse

Harmsen, Stephen C.; Hartzell, Stephen

2008-01-01

Models of the Santa Clara Valley (SCV) 3D velocity structure and 3D finite-difference software are used to predict ground motions from scenario earthquakes on the San Andreas (SAF), Monte Vista/Shannon, South Hayward, and Calaveras faults. Twenty different scenario ruptures are considered that explore different source models with alternative hypocenters, fault dimensions, and rupture velocities and three different velocity models. Ground motion from the full wave field up to 1 Hz is exhibited as maps of peak horizontal velocity and pseudospectral acceleration at periods of 1, 3, and 5 sec. Basin edge effects and amplification in sedimentary basins of the SCV are observed that exhibit effects from shallow sediments with relatively low shear-wave velocity (330 m/sec). Scenario earthquakes have been simulated for events with the following magnitudes: (1) M 6.8–7.4 Calaveras sources, (2) M 6.7–6.9 South Hayward sources, (3) M 6.7 Monte Vista/Shannon sources, and (4) M 7.1–7.2 Peninsula segment of the SAF sources. Ground motions are strongly influenced by source parameters such as rupture velocity, rise time, maximum depth of rupture, hypocenter, and source directivity. Cenozoic basins also exert a strong influence on ground motion. For example, the Evergreen Basin on the northeastern side of the SCV is especially responsive to 3–5-sec energy from most scenario earthquakes. The Cupertino Basin on the southwestern edge of the SCV tends to be highly excited by many Peninsula and Monte Vista fault scenarios. Sites over the interior of the Evergreen Basin can have long-duration coda that reflect the trapping of seismic energy within this basin. Plausible scenarios produce predominantly 5-sec wave trains with greater than 30 cm/sec sustained ground-motion amplitude with greater than 30 sec duration within the Evergreen Basin.

Azimuthal Dependence of the Ground Motion Variability from Scenario Modeling of the 2014 Mw6.0 South Napa, California, Earthquake Using an Advanced Kinematic Source Model

NASA Astrophysics Data System (ADS)

Gallovič, F.

2017-09-01

Strong ground motion simulations require physically plausible earthquake source model. Here, I present the application of such a kinematic model introduced originally by Ruiz et al. (Geophys J Int 186:226-244, 2011). The model is constructed to inherently provide synthetics with the desired omega-squared spectral decay in the full frequency range. The source is composed of randomly distributed overlapping subsources with fractal number-size distribution. The position of the subsources can be constrained by prior knowledge of major asperities (stemming, e.g., from slip inversions), or can be completely random. From earthquake physics point of view, the model includes positive correlation between slip and rise time as found in dynamic source simulations. Rupture velocity and rise time follows local S-wave velocity profile, so that the rupture slows down and rise times increase close to the surface, avoiding unrealistically strong ground motions. Rupture velocity can also have random variations, which result in irregular rupture front while satisfying the causality principle. This advanced kinematic broadband source model is freely available and can be easily incorporated into any numerical wave propagation code, as the source is described by spatially distributed slip rate functions, not requiring any stochastic Green's functions. The source model has been previously validated against the observed data due to the very shallow unilateral 2014 Mw6 South Napa, California, earthquake; the model reproduces well the observed data including the near-fault directivity (Seism Res Lett 87:2-14, 2016). The performance of the source model is shown here on the scenario simulations for the same event. In particular, synthetics are compared with existing ground motion prediction equations (GMPEs), emphasizing the azimuthal dependence of the between-event ground motion variability. I propose a simple model reproducing the azimuthal variations of the between-event ground motion variability, providing an insight into possible refinement of GMPEs' functional forms.

Simultaneous inversion of intrinsic and scattering attenuation parameters incorporating multiple scattering effect

NASA Astrophysics Data System (ADS)

Ogiso, M.

2017-12-01

Heterogeneous attenuation structure is important for not only understanding the earth structure and seismotectonics, but also ground motion prediction. Attenuation of ground motion in high frequency range is often characterized by the distribution of intrinsic and scattering attenuation parameters (intrinsic Q and scattering coefficient). From the viewpoint of ground motion prediction, both intrinsic and scattering attenuation affect the maximum amplitude of ground motion while scattering attenuation also affect the duration time of ground motion. Hence, estimation of both attenuation parameters will lead to sophisticate the ground motion prediction. In this study, we try to estimate both parameters in southwestern Japan in a tomographic manner. We will conduct envelope fitting of seismic coda since coda has sensitivity to both intrinsic attenuation and scattering coefficients. Recently, Takeuchi (2016) successfully calculated differential envelope when these parameters have fluctuations. We adopted his equations to calculate partial derivatives of these parameters since we did not need to assume homogeneous velocity structure. Matrix for inversion of structural parameters would become too huge to solve in a straightforward manner. Hence, we adopted ART-type Bayesian Reconstruction Method (Hirahara, 1998) to project the difference of envelopes to structural parameters iteratively. We conducted checkerboard reconstruction test. We assumed checkerboard pattern of 0.4 degree interval in horizontal direction and 20 km in depth direction. Reconstructed structures well reproduced the assumed pattern in shallower part while not in deeper part. Since the inversion kernel has large sensitivity around source and stations, resolution in deeper part would be limited due to the sparse distribution of earthquakes. To apply the inversion method which described above to actual waveforms, we have to correct the effects of source and site amplification term. We consider these issues to estimate the actual intrinsic and scattering structures of the target region.Acknowledgment We used the waveforms of Hi-net, NIED. This study was supported by the Earthquake Research Institute of the University of Tokyo cooperative research program.

3D Dynamic Rupture Simulations along the Wasatch Fault, Utah, Incorporating Rough-fault Topography

NASA Astrophysics Data System (ADS)

Withers, Kyle; Moschetti, Morgan

2017-04-01

Studies have found that the Wasatch Fault has experienced successive large magnitude (>Mw 7.2) earthquakes, with an average recurrence interval near 350 years. To date, no large magnitude event has been recorded along the fault, with the last rupture along the Salt Lake City segment occurring 1300 years ago. Because of this, as well as the lack of strong ground motion records in basins and from normal-faulting earthquakes worldwide, seismic hazard in the region is not well constrained. Previous numerical simulations have modeled deterministic ground motion in the heavily populated regions of Utah, near Salt Lake City, but were primarily restricted to low frequencies ( 1 Hz). Our goal is to better assess broadband ground motions from the Wasatch Fault Zone. Here, we extend deterministic ground motion prediction to higher frequencies ( 5 Hz) in this region by using physics-based spontaneous dynamic rupture simulations along a normal fault with characteristics derived from geologic observations. We use a summation by parts finite difference code (Waveqlab3D) with rough-fault topography following a self-similar fractal distribution (over length scales from 100 m to the size of the fault) and include off-fault plasticity to simulate ruptures > Mw 6.5. Geometric complexity along fault planes has previously been shown to generate broadband sources with spectral energy matching that of observations. We investigate the impact of varying the hypocenter location, as well as the influence that multiple realizations of rough-fault topography have on the rupture process and resulting ground motion. We utilize Waveqlab3's computational efficiency to model wave-propagation to a significant distance from the fault with media heterogeneity at both long and short spatial wavelengths. These simulations generate a synthetic dataset of ground motions to compare with GMPEs, in terms of both the median and inter and intraevent variability.

Strong ground motion prediction applying dynamic rupture simulations for Beppu-Haneyama Active Fault Zone, southwestern Japan

NASA Astrophysics Data System (ADS)

Yoshimi, M.; Matsushima, S.; Ando, R.; Miyake, H.; Imanishi, K.; Hayashida, T.; Takenaka, H.; Suzuki, H.; Matsuyama, H.

2017-12-01

We conducted strong ground motion prediction for the active Beppu-Haneyama Fault zone (BHFZ), Kyushu island, southwestern Japan. Since the BHFZ runs through Oita and Beppy cities, strong ground motion as well as fault displacement may affect much to the cities.We constructed a 3-dimensional velocity structure of a sedimentary basin, Beppu bay basin, where the fault zone runs through and Oita and Beppu cities are located. Minimum shear wave velocity of the 3d model is 500 m/s. Additional 1-d structure is modeled for sites with softer sediment: holocene plain area. We observed, collected, and compiled data obtained from microtremor surveys, ground motion observations, boreholes etc. phase velocity and H/V ratio. Finer structure of the Oita Plain is modeled, as 250m-mesh model, with empirical relation among N-value, lithology, depth and Vs, using borehole data, then validated with the phase velocity data obtained by the dense microtremor array observation (Yoshimi et al., 2016).Synthetic ground motion has been calculated with a hybrid technique composed of a stochastic Green's function method (for HF wave), a 3D finite difference (LF wave) and 1D amplification calculation. Fault geometry has been determined based on reflection surveys and active fault map. The rake angles are calculated with a dynamic rupture simulation considering three fault segments under a stress filed estimated from source mechanism of earthquakes around the faults (Ando et al., JpGU-AGU2017). Fault parameters such as the average stress drop, a size of asperity etc. are determined based on an empirical relation proposed by Irikura and Miyake (2001). As a result, strong ground motion stronger than 100 cm/s is predicted in the hanging wall side of the Oita plain.This work is supported by the Comprehensive Research on the Beppu-Haneyama Fault Zone funded by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.

Wave induced coastal cliff top ground motions and infragravity wave dissipation under high energy wave conditions.

NASA Astrophysics Data System (ADS)

Earlie, C. S.; le Dantec, N.; Young, A.

2016-12-01

Coastal cliff erosion is a widespread problem that threatens property and infrastructure globally. The prediction of this risk calls for robust understanding of the processes and mechanisms involved in causing coastal cliff failure. Over the last decade, a number of geomorphological studies have highlighted the importance of the relationship between the offshore wave climate and cliff-toe water levels, and the resultant coastal response in terms of cliff-top ground motion and erosion. Field-based studies of instantaneous cliff response to direct wave impact have shown that wave-induced loading of the foreshore leads to cliff-top ground motions that may have the potential to weaken the integrity of the rocks and prepare them for failure. In order to understand wave-cliff interaction and how beach morphodynamics influences cliff-top ground motion and cliff erosion, two field experiments were carried out simultaneously at two locations in Northern Brittany (France). This three-month long winter field campaign (Jan-Mar 2016) included, for the first time, a comparison of cliff-top ground motion and cliff erosion at sites fronted by different beach morphologies (reflective/dissipative), along with monitoring of hydrodynamic forcing and beach topography. The magnitude of cliff-top displacements at both sites were dependent on tidal stage and free water surface elevation at the cliff toe, with the greatest contributions of cliff-top ground motions found at infragravity frequencies (0.05-0.005 Hz). Vertical displacements at infragravity and incident sea-swell (0.1-0.5 Hz) frequencies were greater at the dissipative site, apart from during spring high tide and energetic wave conditions, where displacements were two times that at the reflective site. Combining these wave-cliff interaction data with beach morphology and nearshore bathymetry will be key to understanding the spatial variability in cliff erosion under a variety of environmental settings and forcing conditions.

Revisions to some parameters used in stochastic-method simulations of ground motion

USGS Publications Warehouse

Boore, David; Thompson, Eric M.

2015-01-01

The stochastic method of ground‐motion simulation specifies the amplitude spectrum as a function of magnitude (M) and distance (R). The manner in which the amplitude spectrum varies with M and R depends on physical‐based parameters that are often constrained by recorded motions for a particular region (e.g., stress parameter, geometrical spreading, quality factor, and crustal amplifications), which we refer to as the seismological model. The remaining ingredient for the stochastic method is the ground‐motion duration. Although the duration obviously affects the character of the ground motion in the time domain, it also significantly affects the response of a single‐degree‐of‐freedom oscillator. Recently published updates to the stochastic method include a new generalized double‐corner‐frequency source model, a new finite‐fault correction, a new parameterization of duration, and a new duration model for active crustal regions. In this article, we augment these updates with a new crustal amplification model and a new duration model for stable continental regions. Random‐vibration theory (RVT) provides a computationally efficient method to compute the peak oscillator response directly from the ground‐motion amplitude spectrum and duration. Because the correction factor used to account for the nonstationarity of the ground motion depends on the ground‐motion amplitude spectrum and duration, we also present new RVT correction factors for both active and stable regions.

Ambient Noise Green's Function Simulation of Long-Period Ground Motions for Reverse Faulting

NASA Astrophysics Data System (ADS)

Miyake, H.; Beroza, G. C.

2009-12-01

Long-time correlation of ambient seismic noise has been demonstrated as a useful tool for strong ground motion prediction [Prieto and Beroza, 2008]. An important advantage of ambient noise Green's functions is that they can be used for ground motion simulation without resorting to either complex 3-D velocity structure to develop theoretical Green’s functions, or aftershock records for empirical Green’s function analysis. The station-to-station approach inherent to ambient noise Green’s functions imposes some limits to its application, since they are band-limited, applied at the surface, and for a single force. We explore the applicability of this method to strong motion prediction using the 2007 Chuetsu-oki, Japan, earthquake (Mw 6.6, depth = 9 km), which excited long-period ground motions in and around the Kanto basin almost 200 km from the epicenter. We test the performance of ambient noise Green's function for long-period ground motion simulation. We use three components of F-net broadband data at KZK station, which is located near the source region, as a virtual source, and three components of six F-net stations in and around the Kanto basin to calculate the response. An advantage to applying this approach in Japan is that ambient-noise sources are active in diverse directions. The dominant period of the ambient noise for the F-net datasets is mostly 7 s over the year, and amplitudes are largest in winter. This period matches the dominant periods of the Kanto and Niigata basins. For the 9 components of the ambient noise Green’s functions, we have confirmed long-period components corresponding to Love wave and Rayleigh waves that can be used for simulation of the 2007 Chuetsu-oki earthquake. The relative amplitudes, phases, and durations of the ambient noise Green’s functions at the F-net stations in and around the Kanto basin respect to F-net KZK station are fairly well matched with those of the observed ground motions for the 2007 Chuetsu-oki earthquake.

Source Model of Huge Subduction Earthquakes for Strong Ground Motion Prediction

NASA Astrophysics Data System (ADS)

Iwata, T.; Asano, K.

2012-12-01

It is a quite important issue for strong ground motion prediction to construct the source model of huge subduction earthquakes. Irikura and Miyake (2001, 2011) proposed the characterized source model for strong ground motion prediction, which consists of plural strong ground motion generation area (SMGA, Miyake et al., 2003) patches on the source fault. We obtained the SMGA source models for many events using the empirical Green's function method and found the SMGA size has an empirical scaling relationship with seismic moment. Therefore, the SMGA size can be assumed from that empirical relation under giving the seismic moment for anticipated earthquakes. Concerning to the setting of the SMGAs position, the information of the fault segment is useful for inland crustal earthquakes. For the 1995 Kobe earthquake, three SMGA patches are obtained and each Nojima, Suma, and Suwayama segment respectively has one SMGA from the SMGA modeling (e.g. Kamae and Irikura, 1998). For the 2011 Tohoku earthquake, Asano and Iwata (2012) estimated the SMGA source model and obtained four SMGA patches on the source fault. Total SMGA area follows the extension of the empirical scaling relationship between the seismic moment and the SMGA area for subduction plate-boundary earthquakes, and it shows the applicability of the empirical scaling relationship for the SMGA. The positions of two SMGAs are in Miyagi-Oki segment and those other two SMGAs are in Fukushima-Oki and Ibaraki-Oki segments, respectively. Asano and Iwata (2012) also pointed out that all SMGAs are corresponding to the historical source areas of 1930's. Those SMGAs do not overlap the huge slip area in the shallower part of the source fault which estimated by teleseismic data, long-period strong motion data, and/or geodetic data during the 2011 mainshock. This fact shows the huge slip area does not contribute to strong ground motion generation (10-0.1s). The information of the fault segment in the subduction zone, or historical earthquake source area is also applicable for the construction of SMGA settings for strong ground motion prediction for future earthquakes.

Hybrid broadband Ground Motion simulation based on a dynamic rupture model of the 2011 Mw 9.0 Tohoku earthquake.

NASA Astrophysics Data System (ADS)

Galvez, P.; Somerville, P.; Bayless, J.; Dalguer, L. A.

2015-12-01

The rupture process of the 2011 Tohoku earthquake exhibits depth-dependent variations in the frequency content of seismic radiation from the plate interface. This depth-varying rupture property has also been observed in other subduction zones (Lay et al, 2012). During the Tohoku earthquake, the shallow region radiated coherent low frequency seismic waves whereas the deeper region radiated high frequency waves. Several kinematic inversions (Suzuki et al, 2011; Lee et al, 2011; Bletery et al, 2014; Minson et al, 2014) detected seismic waves below 0.1 Hz coming from the shallow depths that produced slip larger than 40-50 meters close to the trench. Using empirical green functions, Asano & Iwata (2012), Kurahashi and Irikura (2011) and others detected regions of strong ground motion radiation at frequencies up to 10Hz located mainly at the bottom of the plate interface. A recent dynamic model that embodies this depth-dependent radiation using physical models has been developed by Galvez et al (2014, 2015). In this model the rupture process is modeled using a linear weakening friction law with slip reactivation on the shallow region of the plate interface (Galvez et al, 2015). This model reproduces the multiple seismic wave fronts recorded on the Kik-net seismic network along the Japanese coast up to 0.1 Hz as well as the GPS displacements. In the deep region, the rupture sequence is consistent with the sequence of the strong ground motion generation areas (SMGAs) that radiate high frequency ground motion at the bottom of the plate interface (Kurahashi and Irikura, 2013). It remains challenging to perform ground motions fully coupled with a dynamic rupture up to 10 Hz for a megathrust event. Therefore, to generate high frequency ground motions, we make use of the stochastic approach of Graves and Pitarka (2010) but add to the source spectrum the slip rate function of the dynamic model. In this hybrid-dynamic approach, the slip rate function is windowed with Gaussian noise where the duration of the time window and the starting rupture is determined by the slip rate function at each point in the fault (Dalguer et al, 2002). Finally, to validate this method we compare the synthetic seismograms with the recorded ground motion for the 2011 Tohoku earthquake up to 10 Hz.

Effects of listricity on near field ground motions: the kinematic case

NASA Astrophysics Data System (ADS)

Passone, Luca; Mai, P. Martin

2016-04-01

Listric faults are defined as curved faults in which the dip decreases with depth, resulting in a concave upwards shape. Previous works show that breaking the symmetry of faults affects rupture dynamics and near field ground motions (e.g. Oglesby et al., 1998; Nielsen, 1998; Oglesby et al., 2000b; O'Connell et al. 2007). In recent years listric faults have been associated with devastating events, such as the 2008 Mw 7.9 Wenchuan earthquake that caused almost 150 billion of damage, and the 1999 Mw 7.6 Chi- Chi earthquake that caused 10 billion worth of damage, each of them responsible also for tens of thousands of injured and dead. We focus on quantifying near field ground motions as a function of initial dip, style (normal or reverse) and a listricity. To construct a listric profile for the simulations we use an exponential function (Wang et al., 2009) that approximates the dip angle for a certain depth as a function of the depth itself, the initial dip angle and a listricity factor. We then generate an ensemble of source models, with initial dip ranging from 10 to 90 degrees and a listricity factor from 5 to 20. Finally, heterogeneous slip distributions are created for a magnitude Mw 6.8 earthquake. Choosing different hypocenter locations and rupture velocities, we construct a range of kinematic source models that are resolved on both the listric and planar-fault geometry. We then compute the near-source seismic wavefield within a uniform isotropic medium using a generalized 3D finite-difference method. The listric and planar simulations are then compared, and their differences quantified. Initial results show a secondary directivity effect once the listricity factor exceeds 10 for the larger initial dip faults, thus inducing a change in the azimuthal angle with respect of the epicenter where peak ground motions are experienced. At the same time, overall PGV values are decreased, more so for geometries with higher listricity factors. With the knowledge acquired, a ground motion reduction factor can be applied to ground motion prediction equations when the fault is considered to be listric and hazard maps should re-adjusted to cater for the relocation of peak ground motions due to directivity effects.

Chapter A. The Loma Prieta, California, Earthquake of October 17, 1989 - Strong Ground Motion

USGS Publications Warehouse

Borcherdt, Roger D.

1994-01-01

Strong ground motion generated by the Loma Prieta, Calif., earthquake (MS~7.1) of October 17, 1989, resulted in at least 63 deaths, more than 3,757 injuries, and damage estimated to exceed $5.9 billion. Strong ground motion severely damaged critical lifelines (freeway overpasses, bridges, and pipelines), caused severe damage to poorly constructed buildings, and induced a significant number of ground failures associated with liquefaction and landsliding. It also caused a significant proportion of the damage and loss of life at distances as far as 100 km from the epicenter. Consequently, understanding the characteristics of the strong ground motion associated with the earthquake is fundamental to understanding the earthquake's devastating impact on society. The papers assembled in this chapter address this problem. Damage to vulnerable structures from the earthquake varied substantially with the distance from the causative fault and the type of underlying geologic deposits. Most of the damage and loss of life occurred in areas underlain by 'soft soil'. Quantifying these effects is important for understanding the tragic concentrations of damage in such areas as Santa Cruz and the Marina and Embarcadero Districts of San Francisco, and the failures of the San Francisco-Oakland Bay Bridge and the Interstate Highway 880 overpass. Most importantly, understanding these effects is a necessary prerequisite for improving mitigation measures for larger earthquakes likely to occur much closer to densely urbanized areas in the San Francisco Bay region. The earthquake generated an especially important data set for understanding variations in the severity of strong ground motion. Instrumental strong-motion recordings were obtained at 131 sites located from about 6 to 175 km from the rupture zone. This set of recordings, the largest yet collected for an event of this size, was obtained from sites on various geologic deposits, including a unique set on 'soft soil' deposits (artificial fill and bay mud). These exceptional ground-motion data are used by the authors of the papers in this chapter to infer radiation characteristics of the earthquake source, identify dominant propagation characteristics of the Earth?s crust, quantify amplification characteristics of near-surface geologic deposits, develop general amplification factors for site-dependent building-code provisions, and revise earthquake-hazard assessments for the San Francisco Bay region. Interpretations of additional data recorded in well-instrumented buildings, dams, and freeway overpasses are provided in other chapters of this report.

Applications of PTTI to new techniques for determining crustal movements, polar motion, and the rotation of the earth

NASA Technical Reports Server (NTRS)

Bender, P. L.

1974-01-01

New extra-terrestrial techniques are discussed for geodesy and geodynamics include laser range measurements to the moon or to artificial satellites, Doppler measurements with the Transit satellite system, and both independent-clock and linked-antenna microwave interferometry. The ways in which PTTI measurements are used in these techniques will be reviewed, and the accuracies expected during the latter half of the 1970's will be discussed. At least 3 of the techniques appear capable of giving accuracies of 5 cm or better in each coordinate for many points on the earth's surface, and comparable accuracies for the earth's rotation and polar motion. For fixed stations or for sites a few hundred km apart, baseline lengths accurate to 1 cm may be achieved. Ways in which the complementary aspects of the different techniques can be exploited will be discussed, as well as how they tie in with improved ground techniques for determining crustal movements. Some recent results from the extra-terrestrial methods will be mentioned.

Numerical Simulation of Strong Ground Motion at Mexico City:A Hybrid Approach for Efficient Evaluation of Site Amplification and Path Effects for Different Types of Earthquakes

NASA Astrophysics Data System (ADS)

Cruz, H.; Furumura, T.; Chavez-Garcia, F. J.

2002-12-01

The estimation of scenarios of the strong ground motions caused by future great earthquakes is an important problem in strong motion seismology. This was pointed out by the great 1985 Michoacan earthquake, which caused a great damage in Mexico City, 300 km away from the epicenter. Since the seismic wavefield is characterized by the source, path and site effects, the pattern of strong motion damage from different types of earthquakes should differ significantly. In this study, the scenarios for intermediate-depth normal-faulting, shallow-interplate thrust faulting, and crustal earthquakes have been estimated using a hybrid simulation technique. The character of the seismic wavefield propagating from the source to Mexico City for each earthquake was first calculated using the pseudospectral method for 2D SH waves. The site amplifications in the shallow structure of Mexico City are then calculated using the multiple SH wave reverberation theory. The scenarios of maximum ground motion for both inslab and interplate earthquakes obtained by the simulation show a good agreement with the observations. This indicates the effectiveness of the hybrid simulation approach to investigate the strong motion damage for future earthquakes.

7 CFR 283.18 - Motions and requests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... particular order, ruling, or action desired and the grounds therefor. (d) Response to motions and requests... 7 Agriculture 4 2011-01-01 2011-01-01 false Motions and requests. 283.18 Section 283.18... Claims of $50,000 or More § 283.18 Motions and requests. (a) Filing. All motions and requests shall be...

7 CFR 283.18 - Motions and requests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... particular order, ruling, or action desired and the grounds therefor. (d) Response to motions and requests... 7 Agriculture 4 2010-01-01 2010-01-01 false Motions and requests. 283.18 Section 283.18... Claims of $50,000 or More § 283.18 Motions and requests. (a) Filing. All motions and requests shall be...

14 CFR 13.226 - Public disclosure of evidence.

Code of Federal Regulations, 2014 CFR

2014-01-01

... law judge and serving a copy of the motion on each party. The party shall state the specific grounds for nondisclosure in the motion. (b) The administrative law judge shall grant the motion to withhold information in the record if, based on the motion and any response to the motion, the administrative law judge...

14 CFR 13.226 - Public disclosure of evidence.

Code of Federal Regulations, 2012 CFR

2012-01-01

... law judge and serving a copy of the motion on each party. The party shall state the specific grounds for nondisclosure in the motion. (b) The administrative law judge shall grant the motion to withhold information in the record if, based on the motion and any response to the motion, the administrative law judge...

14 CFR 13.226 - Public disclosure of evidence.

Code of Federal Regulations, 2013 CFR

2013-01-01

... law judge and serving a copy of the motion on each party. The party shall state the specific grounds for nondisclosure in the motion. (b) The administrative law judge shall grant the motion to withhold information in the record if, based on the motion and any response to the motion, the administrative law judge...

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

Rutqvist, Jonny; Cappa, Frédéric; Rinaldi, Antonio P.

In this paper, we present model simulations of ground motions caused by CO 2 -injection-induced fault reactivation and analyze the results in terms of the potential for damage to ground surface structures and nuisance to the local human population. It is an integrated analysis from cause to consequence, including the whole chain of processes starting from earthquake inception in the subsurface, wave propagation toward the ground surface, and assessment of the consequences of ground vibration. For a small magnitude (M w =3) event at a hypocenter depth of about 1000m, we first used the simulated ground-motion wave train in anmore » inverse analysis to estimate source parameters (moment magnitude, rupture dimensions and stress drop), achieving good agreement and thereby verifying the modeling of the chain of processes from earthquake inception to ground vibration. We then analyzed the ground vibration results in terms of peak ground acceleration (PGA), peak ground velocity (PGV) and frequency content, with comparison to U.S. Geological Survey's instrumental intensity scales for earthquakes and the U.S. Bureau of Mines' vibration criteria for cosmetic damage to buildings, as well as human-perception vibration limits. Our results confirm the appropriateness of using PGV (rather than PGA) and frequency for the evaluation of potential ground-vibration effects on structures and humans from shallow injection-induced seismic events. For the considered synthetic M w =3 event, our analysis showed that the short duration, high frequency ground motion may not cause any significant damage to surface structures, but would certainly be felt by the local population.« less

Response of high-rise and base-isolated buildings to a hypothetical M w 7.0 blind thrust earthquake

USGS Publications Warehouse

Heaton, T.H.; Hall, J.F.; Wald, D.J.; Halling, M.W.

1995-01-01

High-rise flexible-frame buildings are commonly considered to be resistant to shaking from the largest earthquakes. In addition, base isolation has become increasingly popular for critical buildings that should still function after an earthquake. How will these two types of buildings perform if a large earthquake occurs beneath a metropolitan area? To answer this question, we simulated the near-source ground motions of a Mw 7.0 thrust earthquake and then mathematically modeled the response of a 20-story steel-frame building and a 3-story base-isolated building. The synthesized ground motions were characterized by large displacement pulses (up to 2 meters) and large ground velocities. These ground motions caused large deformation and possible collapse of the frame building, and they required exceptional measures in the design of the base-isolated building if it was to remain functional.

Distributions of strong ground motion due to dynamic ruptures across a bimaterial fault: Implications for seismic hazard analyses

NASA Astrophysics Data System (ADS)

Yuan, Jie; Zhu, Shoubiao

2016-12-01

We perform 2-D finite element calculations of mode II rupture along a bimaterial interface governed by regularized rate- and state-dependent friction law, with the goal of understanding how the bimaterial interface influences the strong ground motion. By comparison with properties of rupture in a homogeneous solid, we found that bimaterial mechanism is important for earthquake ruptures and influences the strong ground motion significantly. The simulated results show that mode II rupture evolves with propagation distance along a bimaterial interface to a unilateral wrinkle-like pulse in the direction of slip on the compliant side of the fault, namely in the positive direction. Strong ground motion caused by seismic waves emanated from the rupture propagation is asymmetrically distributed in space. The computed peak ground acceleration (PGA) is high in the near-fault region. Particularly, PGA is much larger in the region on the side in the positive direction. In addition, it is greater in the more compliant area of the model than that in the stiffer area with corresponding locations. Moreover, the differential PGA due to bimaterial effect increases with increasing degree of material contrast across the fault. It is hoped that the results obtained in this investigation will provide some implications for seismic hazard assessment and fault rupture mechanics.

Probabilistic versus deterministic hazard assessment in liquefaction susceptible zones

NASA Astrophysics Data System (ADS)

Daminelli, Rosastella; Gerosa, Daniele; Marcellini, Alberto; Tento, Alberto

2015-04-01

Probabilistic seismic hazard assessment (PSHA), usually adopted in the framework of seismic codes redaction, is based on Poissonian description of the temporal occurrence, negative exponential distribution of magnitude and attenuation relationship with log-normal distribution of PGA or response spectrum. The main positive aspect of this approach stems into the fact that is presently a standard for the majority of countries, but there are weak points in particular regarding the physical description of the earthquake phenomenon. Factors like site effects, source characteristics like duration of the strong motion and directivity that could significantly influence the expected motion at the site are not taken into account by PSHA. Deterministic models can better evaluate the ground motion at a site from a physical point of view, but its prediction reliability depends on the degree of knowledge of the source, wave propagation and soil parameters. We compare these two approaches in selected sites affected by the May 2012 Emilia-Romagna and Lombardia earthquake, that caused widespread liquefaction phenomena unusually for magnitude less than 6. We focus on sites liquefiable because of their soil mechanical parameters and water table level. Our analysis shows that the choice between deterministic and probabilistic hazard analysis is strongly dependent on site conditions. The looser the soil and the higher the liquefaction potential, the more suitable is the deterministic approach. Source characteristics, in particular the duration of strong ground motion, have long since recognized as relevant to induce liquefaction; unfortunately a quantitative prediction of these parameters appears very unlikely, dramatically reducing the possibility of their adoption in hazard assessment. Last but not least, the economic factors are relevant in the choice of the approach. The case history of 2012 Emilia-Romagna and Lombardia earthquake, with an officially estimated cost of 6 billions Euros, shows that geological and geophysical investigations necessary to assess a reliable deterministic hazard evaluation are largely justified.

Normal Mode Analysis of Ambient-Noise Induced Free Oscillations of a Slender Medieval Masonry Tower in Bologna (Italy)

NASA Astrophysics Data System (ADS)

Morelli, A.; Azzara, R. M.; Cavaliere, A.; Zaccarelli, L.

2014-12-01

Analysis of the oscillations of buildings — either excited by earthquakes or by ambient noise — has become an effective tool to evaluate the response of such structures to strong ground motion, and hence to assess their seismic vulnerability. Response to small-amplitude ground motion may also provide crucial information on the elastic and anelastic properties of a structure — essential in the case of historical buildings — and constrain numerical full dynamic structural analyses. We report about an analysis carried out for a tall medieval monumental building in the urban center of the Norther Italian city of Bologna. Seismic monitoring, carried on for six months using field seismic instrumentation, has revealed the response to ambient noise, and has allowed to reconstruct, with high detail, the free oscillation modes of the tower. At 97 meters, the XII-century tower of the Asinelli is the tallest masonry building in Europe, and the most slender. We measured the fundamental, and several higher-order, flexural normal modes of oscillation, as well as the fundamental torsional mode. Asymmetry due to non-coincidence of centers of mass and of stiffness produces slightly different modal frequencies of oscillation in two orthogonal directions, consistently with dynamical modeling. Horizontal particle-motion polarization plots show the cyclic energy transfer between two degrees of freedom of the system. The Asinelli spectral signature can also be easily recognized in the motion recorded at the base of nearby Garisenda. We verify that there is correlation of spectral amplitudes with time of the day — in agreement with expected time-variance of anthropic disturbance —- but also with wind velocity and, intriguingly, with temperature variations inside the buidings. We are using these data to adjust the numerical dynamical models of the buildings, to examine time variations of behavior, and to identify the origin of anthropogenic sources of vibration in view of their possible mitigation.

Sensitivity analysis of seismic hazard for the northwestern portion of the state of Gujarat, India

USGS Publications Warehouse

Petersen, M.D.; Rastogi, B.K.; Schweig, E.S.; Harmsen, S.C.; Gomberg, J.S.

2004-01-01

We test the sensitivity of seismic hazard to three fault source models for the northwestern portion of Gujarat, India. The models incorporate different characteristic earthquake magnitudes on three faults with individual recurrence intervals of either 800 or 1600 years. These recurrence intervals imply that large earthquakes occur on one of these faults every 266-533 years, similar to the rate of historic large earthquakes in this region during the past two centuries and for earthquakes in intraplate environments like the New Madrid region in the central United States. If one assumes a recurrence interval of 800 years for large earthquakes on each of three local faults, the peak ground accelerations (PGA; horizontal) and 1-Hz spectral acceleration ground motions (5% damping) are greater than 1 g over a broad region for a 2% probability of exceedance in 50 years' hazard level. These probabilistic PGAs at this hazard level are similar to median deterministic ground motions. The PGAs for 10% in 50 years' hazard level are considerably lower, generally ranging between 0.2 g and 0.7 g across northwestern Gujarat. Ground motions calculated from our models that consider fault interevent times of 800 years are considerably higher than other published models even though they imply similar recurrence intervals. These higher ground motions are mainly caused by the application of intraplate attenuation relations, which account for less severe attenuation of seismic waves when compared to the crustal interplate relations used in these previous studies. For sites in Bhuj and Ahmedabad, magnitude (M) 7 3/4 earthquakes contribute most to the PGA and the 0.2- and 1-s spectral acceleration ground motion maps at the two considered hazard levels. ?? 2004 Elsevier B.V. All rights reserved.

Drifting while stepping in place in old adults: Association of self-motion perception with reference frame reliance and ground optic flow sensitivity.

PubMed

Agathos, Catherine P; Bernardin, Delphine; Baranton, Konogan; Assaiante, Christine; Isableu, Brice

2017-04-07

Optic flow provides visual self-motion information and is shown to modulate gait and provoke postural reactions. We have previously reported an increased reliance on the visual, as opposed to the somatosensory-based egocentric, frame of reference (FoR) for spatial orientation with age. In this study, we evaluated FoR reliance for self-motion perception with respect to the ground surface. We examined how effects of ground optic flow direction on posture may be enhanced by an intermittent podal contact with the ground, and reliance on the visual FoR and aging. Young, middle-aged and old adults stood quietly (QS) or stepped in place (SIP) for 30s under static stimulation, approaching and receding optic flow on the ground and a control condition. We calculated center of pressure (COP) translation and optic flow sensitivity was defined as the ratio of COP translation velocity over absolute optic flow velocity: the visual self-motion quotient (VSQ). COP translation was more influenced by receding flow during QS and by approaching flow during SIP. In addition, old adults drifted forward while SIP without any imposed visual stimulation. Approaching flow limited this natural drift and receding flow enhanced it, as indicated by the VSQ. The VSQ appears to be a motor index of reliance on the visual FoR during SIP and is associated with greater reliance on the visual and reduced reliance on the egocentric FoR. Exploitation of the egocentric FoR for self-motion perception with respect to the ground surface is compromised by age and associated with greater sensitivity to optic flow. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Update of the Graizer-Kalkan ground-motion prediction equations for shallow crustal continental earthquakes

USGS Publications Warehouse

Graizer, Vladimir; Kalkan, Erol

2015-01-01

A ground-motion prediction equation (GMPE) for computing medians and standard deviations of peak ground acceleration and 5-percent damped pseudo spectral acceleration response ordinates of maximum horizontal component of randomly oriented ground motions was developed by Graizer and Kalkan (2007, 2009) to be used for seismic hazard analyses and engineering applications. This GMPE was derived from the greatly expanded Next Generation of Attenuation (NGA)-West1 database. In this study, Graizer and Kalkan’s GMPE is revised to include (1) an anelastic attenuation term as a function of quality factor (Q0) in order to capture regional differences in large-distance attenuation and (2) a new frequency-dependent sedimentary-basin scaling term as a function of depth to the 1.5-km/s shear-wave velocity isosurface to improve ground-motion predictions for sites on deep sedimentary basins. The new model (GK15), developed to be simple, is applicable to the western United States and other regions with shallow continental crust in active tectonic environments and may be used for earthquakes with moment magnitudes 5.0–8.0, distances 0–250 km, average shear-wave velocities 200–1,300 m/s, and spectral periods 0.01–5 s. Directivity effects are not explicitly modeled but are included through the variability of the data. Our aleatory variability model captures inter-event variability, which decreases with magnitude and increases with distance. The mixed-effects residuals analysis shows that the GK15 reveals no trend with respect to the independent parameters. The GK15 is a significant improvement over Graizer and Kalkan (2007, 2009), and provides a demonstrable, reliable description of ground-motion amplitudes recorded from shallow crustal earthquakes in active tectonic regions over a wide range of magnitudes, distances, and site conditions.

Empirical ground-motion relations for subduction-zone earthquakes and their application to Cascadia and other regions

USGS Publications Warehouse

Atkinson, G.M.; Boore, D.M.

2003-01-01

Ground-motion relations for earthquakes that occur in subduction zones are an important input to seismic-hazard analyses in many parts of the world. In the Cascadia region (Washington, Oregon, northern California, and British Columbia), for example, there is a significant hazard from megathrust earthquakes along the subduction interface and from large events within the subducting slab. These hazards are in addition to the hazard from shallow earthquakes in the overlying crust. We have compiled a response spectra database from thousands of strong-motion recordings from events of moment magnitude (M) 5-8.3 occurring in subduction zones around the world, including both interface and in-slab events. The 2001 M 6.8 Nisqually and 1999 M 5.9 Satsop earthquakes are included in the database, as are many records from subduction zones in Japan (Kyoshin-Net data), Mexico (Guerrero data), and Central America. The size of the database is four times larger than that available for previous empirical regressions to determine ground-motion relations for subduction-zone earthquakes. The large dataset enables improved determination of attenuation parameters and magnitude scaling, for both interface and in-slab events. Soil response parameters are also better determined by the data. We use the database to develop global ground-motion relations for interface and in-slab earthquakes, using a maximum likelihood regression method. We analyze regional variability of ground-motion amplitudes across the global database and find that there are significant regional differences. In particular, amplitudes in Cascadia differ by more than a factor of 2 from those in Japan for the same magnitude, distance, event type, and National Earthquake Hazards Reduction Program (NEHRP) soil class. This is believed to be due to regional differences in the depth of the soil profile, which are not captured by the NEHRP site classification scheme. Regional correction factors to account for these differences are proposed for Cascadia and Japan. The results of this study differ significantly from previous analyses based on more limited data and have important implications for seismic-hazard analysis. The ground-motion relations predict that a great megathrust earthquake (M ???8) at a fault distance of about 100 km would produce pseudoacceleration (PSA), 5% damped, horizontal component on soil sites of about 110 cm/sec2 at 0.5 Hz, 660 cm/sec2 at 2.5 Hz, and 410 cm/sec2 at 5 Hz, with a peak ground acceleration of about 180 cm/ sec2 . These damaging levels of motion would be experienced over a very large area, corresponding to a rectangular area about 300 km wide by 500 km long. Large in-slab events (M 7.5) would produce even higher PSA values within 100 km of the fault, but the in-slab motions attenuate much more rapidly with distance. Thus the hazard posed by moderate to large in-slab events such as the 2001 Nisqually earthquake is modest compared to that of a Cascadia megathrust earthquake of M ???8, in terms of the area that would experience damaging levels of ground motion.

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

Thein, Pyi Soe, E-mail: pyisoethein@yahoo.com; Pramumijoyo, Subagyo; Wilopo, Wahyu

In this study, we investigated the strong ground motion characteristics under Palu City, Indonesia. The shear wave velocity structures evaluated by eight microtremors measurement are the most applicable to determine the thickness of sediments and average shear wave velocity with Vs ≤ 300 m/s. Based on subsurface underground structure models identified, earthquake ground motion was estimated in the future Palu-Koro earthquake by using statistical green’s function method. The seismic microzonation parameters were carried out by considering several significant controlling factors on ground response at January 23, 2005 earthquake.

Principles for selecting earthquake motions in engineering design of large dams

USGS Publications Warehouse

Krinitzsky, E.L.; Marcuson, William F.

1983-01-01

This report gives a synopsis of the various tools and techniques used in selecting earthquake ground motion parameters for large dams. It presents 18 charts giving newly developed relations for acceleration, velocity, and duration versus site earthquake intensity for near- and far-field hard and soft sites and earthquakes having magnitudes above and below 7. The material for this report is based on procedures developed at the Waterways Experiment Station. Although these procedures are suggested primarily for large dams, they may also be applicable for other facilities. Because no standard procedure exists for selecting earthquake motions in engineering design of large dams, a number of precautions are presented to guide users. The selection of earthquake motions is dependent on which one of two types of engineering analyses are performed. A pseudostatic analysis uses a coefficient usually obtained from an appropriate contour map; whereas, a dynamic analysis uses either accelerograms assigned to a site or specified respunse spectra. Each type of analysis requires significantly different input motions. All selections of design motions must allow for the lack of representative strong motion records, especially near-field motions from earthquakes of magnitude 7 and greater, as well as an enormous spread in the available data. Limited data must be projected and its spread bracketed in order to fill in the gaps and to assure that there will be no surprises. Because each site may have differing special characteristics in its geology, seismic history, attenuation, recurrence, interpreted maximum events, etc., as integrated approach gives best results. Each part of the site investigation requires a number of decisions. In some cases, the decision to use a 'least ork' approach may be suitable, simply assuming the worst of several possibilities and testing for it. Because there are no standard procedures to follow, multiple approaches are useful. For example, peak motions at a site may be obtained from several methods that involve magnitude of earthquake, distance from source, and corresponding motions; or, alternately, peak motions may be assigned from other correlations based on earthquake intensity. Various interpretations exist to account for duration, recurrence, effects of site conditions, etc. Comparison of the various interpretations can be very useful. Probabilities can be assigned; however, they can present very serious problems unless appropriate care is taken when data are extrapolated beyond their data base. In making deterministic judgments, probabilistic data can provide useful guidance in estimating the uncertainties of the decision. The selection of a design ground motion for large dams is based in the end on subjective judgments which should depend, to an important extent, on the consequences of failure. Usually, use of a design value of ground motion representing a mean plus one standard deviation of possible variation in the mean of the data puts one in a conservative position. If failure presents no hazard to life, lower values of design ground motion may be justified, providing there are cost benefits and the risk is acceptable to the owner. Where a large hazard to life exists (i.e., a dam above an urbanized area) one may wish to use values of design ground motion that approximate the very worst case. The selection of a design ground motion must be appropriate for its particular set of circumstances.

Seismic shaking scenarios in realistic 3D crustal model of Northern Italy

NASA Astrophysics Data System (ADS)

Molinari, I.; Morelli, A.; Basini, P.; Berbellini, A.

2013-12-01

Simulation of seismic wave propagation in realistic crustal structures is a fundamental tool to evaluate earthquake-generated ground shaking and assess seismic hazard. Current-generation numerical codes, and modern HPC infrastructures, allow for realistic simulations in complex 3D geologic structures. We apply such methodology to the Po Plain in Northern Italy -- a region with relatively rare earthquakes but having large property and industrial exposure, as it became clear during the two M~6 events of May 20-29, 2012. Historical seismicity is well known in this region, with maximum magnitudes estimates reaching M~7, and wave field amplitudes may be significantly amplified by the presence of the very thick sedimentary basin. Our goal is to produce estimates of expected ground shaking in Northern Italy through detailed deterministic simulations of ground motion due to expected earthquakes. We defined a three-dimensional model of the earth's crust using geo-statistical tools to merge the abundant information existing in the form of borehole data and seismic reflection profiles that had been shot in the '70s and the '80s for hydrocarbon exploration. Such information, that has been used by geologists to infer the deep structural setup, had never been merged to build a 3D model to be used for seismological simulations. We implement the model in SPECFEM3D_Cartesian and a hexahedral mesh with elements of ~2km, that allows us to simulate waves with minimum period of ~2 seconds. The model has then been optimized through comparison between simulated and recorded seismograms for the ~20 moderate-magnitude events (Mw > 4.5) that have been instrumentally recorded in the last 15 years. Realistic simulations in the frequency band of most common engineering relevance -- say, ~1 Hz -- at such a large scale would require an extremely detailed structural model, currently not available, and prohibitive computational resources. However, an interest is growing in longer period ground motion -- that impacts on the seismic response of taller structures (Cauzzi and Faccioli, 2008) -- and it is not unusual to consider the wave field up to 20s. In such period range, our Po Plain structural model has shown to be able to reproduce well basin resonance and amplification effects at stations boarding the sedimentary plain. We then simulate seismic shaking scenarios for possible sources tied to devastating historical earthquakes that are known to have occurred in the region --- such as the M~6 event that hit Modena in 1501; and the Verona, M~6.7 in 1117, quake that caused well-documented strong effects in an unusually wide area with radius of hundreds of kilometers. We explore different source geometries and rupture histories for each earthquake. We mainly focus our attention on the synthesis of the prominent surface waves that are highly amplified in deep sedimentary basin structures (e.g., Smerzini et al, 2011; Koketsu and Miyage, 2008). Such simulations hold high relevance because of the large local property exposure, due to extensive industrial and touristic infrastructure. We show that deterministic ground motion calculation can indeed provide information to be actively used to mitigate the effects of desctructive earthquakes on critical infrastructures.

Report of Earthquake Drills with Experiences of Ground Motion in Childcare for Young Children, Japan

NASA Astrophysics Data System (ADS)

Yamada, N.

2013-12-01

After the Great East Japan Earthquake of 2011, this disaster has become one of the opportunities to raise awareness of earthquake and tsunami disaster prevention, and the improvement of disaster prevention education is to be emphasized. The influences of these bring the extension to the spatial axis in Japan, and also, it is important to make a development of the education with continuous to the expansion of time axes. Although fire or earthquake drills as the disaster prevention education are often found in Japan, the children and teachers only go from school building to outside. Besides, only the shortness of the time to spend for the drill often attracts attention. The complementary practice education by the cooperation with experts such as the firefighting is practiced, but the verification of the effects is not enough, and it is the present conditions that do not advance to the study either. Although it is expected that improvement and development of the disaster prevention educations are accomplished in future, there are a lot of the problems. Our target is construction and utilization of material contributing to the education about "During the strong motion" in case of the earthquake which may experience even if wherever of Japan. One of the our productions is the handicraft shaking table to utilize as teaching tools of the education to protect the body which is not hurt at the time of strong motion. This made much of simplicity than high reproduction of the earthquake ground motions. We aimed to helping the disaster prevention education including not only the education for young children but also for the school staff and their parents. In this report, the focusing on a way of the non-injured during the time of the earthquake ground motion, and adopting activity of the play, we are going to show the example of the framework of earthquake disaster prevention childcare through the virtual experience. This presentation has a discussion as a practice study with the program of the earthquake disaster prevention childcare for young children (e.g. from 0 to 5 years old children in kindergarten and nursery school) for the above problems by the cooperation and the collaborative investigation with the schools. This study was supported by Grant-in-Aid for Young Scientists (B), No. 23700957 of the Japan Ministry of Education, Culture, Sport, Science, and Technology (MEXT). We special thank the all person concerned with kindergartens and nurseries in this study.

49 CFR Appendix A to Part 237 - Supplemental Statement of Agency Policy on the Safety of Railroad Bridges

Code of Federal Regulations, 2011 CFR

2011-10-01

... pier reactions as necessary for a comprehensive evaluation and statement of the capacity of a bridge... seismic activity in an area. (c) The predicted attenuation of ground motion varies considerably within the United States. Local ground motion attenuation values and the magnitude of an earthquake both influence...

Directivity in NGA earthquake ground motions: Analysis using isochrone theory

USGS Publications Warehouse

Spudich, P.; Chiou, B.S.J.

2008-01-01

We present correction factors that may be applied to the ground motion prediction relations of Abrahamson and Silva, Boore and Atkinson, Campbell and Bozorgnia, and Chiou and Youngs (all in this volume) to model the azimuthally varying distribution of the GMRotI50 component of ground motion (commonly called 'directivity') around earthquakes. Our correction factors may be used for planar or nonplanar faults having any dip or slip rake (faulting mechanism). Our correction factors predict directivity-induced variations of spectral acceleration that are roughly half of the strike-slip variations predicted by Somerville et al. (1997), and use of our factors reduces record-to-record sigma by about 2-20% at 5 sec or greater period. ?? 2008, Earthquake Engineering Research Institute.

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

Rodgers, A. J.

This is the final report for United States Geological Survey (USGS) National Earthquake Hazard Reduction Program (NEHRP) Project 08HQGR0022, entitled “Quantifying Uncertainties in Ground Motion Simulations for Scenario Earthquakes on the HaywardRodgers Creek Fault System Using the USGS 3D Seismic Velocity Model and Realistic Pseudodynamics Ruptures”. Work for this project involved three-dimensional (3D) simulations of ground motions for Hayward Fault (HF) earthquakes. We modeled moderate events on the HF and used them to evaluate the USGS 3D model of the San Francisco Bay Area. We also contributed to ground motions modeling effort for a large suite of scenario earthquakes onmore » the HF. Results were presented at conferences (see appendix) and in one peer-reviewed publication (Aagaard et al., 2010).« less

Messier 35 (NGC 2168) DANCe. I. Membership, proper motions, and multiwavelength photometry

NASA Astrophysics Data System (ADS)

Bouy, H.; Bertin, E.; Barrado, D.; Sarro, L. M.; Olivares, J.; Moraux, E.; Bouvier, J.; Cuillandre, J.-C.; Ribas, Á.; Beletsky, Y.

2015-03-01

Context. Messier 35 (NGC 2168) is an important young nearby cluster. Its age, richness and relative proximity make it an ideal target for stellar evolution studies. The Kepler K2 mission recently observed it and provided a high accuracy photometric time series of a large number of sources in this area of the sky. Identifying the cluster's members is therefore of high importance to optimize the interpretation and analysis of the Kepler K2 data. Aims: We aim to identify the cluster's members by deriving membership probabilities for the sources within 1° of the cluster's center, which is farther away than equivalent previous studies. Methods: We measure accurate proper motions and multiwavelength (optical and near-infrared) photometry using ground-based archival images of the cluster. We use these measurements to compute membership probabilities. The list of candidate members from the literature is used as a training set to identify the cluster's locus in a multidimensional space made of proper motions, luminosities, and colors. Results: The final catalog includes 338 892 sources with multiwavelength photometry. Approximately half (194 452) were detected at more than two epochs and we measured their proper motion and used it to derive membership probability. A total of 4349 candidate members with membership probabilities greater than 50% are found in this sample in the luminosity range between 10 mag and 22 mag. The slow proper motion of the cluster and the overlap of its sequence with the field and background sequences in almost all color-magnitude and color-color diagrams complicate the analysis and the contamination level is expected to be significant. Our study, nevertheless, provides a coherent and quantitative membership analysis of Messier 35 based on a large fraction of the best ground-based data sets obtained over the past 18 years. As such, it represents a valuable input for follow-up studies using, in particular, the Kepler K2 photometric time series. Table 3 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/575/A120

Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake

NASA Astrophysics Data System (ADS)

Takai, Nobuo; Shigefuji, Michiko; Rajaure, Sudhir; Bijukchhen, Subeg; Ichiyanagi, Masayoshi; Dhital, Megh Raj; Sasatani, Tsutomu

2016-01-01

On 25 April 2015, a large earthquake of Mw 7.8 occurred along the Main Himalayan Thrust fault in central Nepal. It was caused by a collision of the Indian Plate beneath the Eurasian Plate. The epicenter was near the Gorkha region, 80 km northwest of Kathmandu, and the rupture propagated toward east from the epicentral region passing through the sediment-filled Kathmandu Valley. This event resulted in over 8000 fatalities, mostly in Kathmandu and the adjacent districts. We succeeded in observing strong ground motions at our four observation sites (one rock site and three sedimentary sites) in the Kathmandu Valley during this devastating earthquake. While the observed peak ground acceleration values were smaller than the predicted ones that were derived from the use of a ground motion prediction equation, the observed peak ground velocity values were slightly larger than the predicted ones. The ground velocities observed at the rock site (KTP) showed a simple velocity pulse, resulting in monotonic-step displacements associated with the permanent tectonic offset. The vertical ground velocities observed at the sedimentary sites had the same pulse motions that were observed at the rock site. In contrast, the horizontal ground velocities as well as accelerations observed at three sedimentary sites showed long duration with conspicuous long-period oscillations, due to the valley response. The horizontal valley response was characterized by large amplification (about 10) and prolonged oscillations. However, the predominant period and envelope shape of their oscillations differed from site to site, indicating a complicated basin structure. Finally, on the basis of the velocity response spectra, we show that the horizontal long-period oscillations on the sedimentary sites had enough destructive power to damage high-rise buildings with natural periods of 3 to 5 s.

On the generation of tangential ground motion by underground explosions in jointed rocks

NASA Astrophysics Data System (ADS)

Vorobiev, Oleg; Ezzedine, Souheil; Antoun, Tarabay; Glenn, Lewis

2015-03-01

This paper describes computational studies of tangential ground motions generated by spherical explosions in a heavily jointed granite formation. Various factors affecting the shear wave generation are considered, including joint spacing, orientation and frictional properties. Simulations are performed both in 2-D for a single joint set to elucidate the basic response mechanisms, and in 3-D for multiple joint sets to realistically represent in situ conditions in a realistic geological setting. The joints are modelled explicitly using both contact elements and weakness planes in the material. Simulations are performed both deterministically and stochastically to quantify the effects of geological uncertainties on near field ground motions. The mechanical properties of the rock and the joints as well as the joint spacing and orientation are taken from experimental test data and geophysical logs corresponding to the Climax Stock granitic outcrop, which is the geological setting of the source physics experiment (SPE). Agreement between simulation results and near field wave motion data from SPE enables newfound understanding of the origin and extent of non-spherical motions associated with underground explosions in fractured geological media.

Uncertainties in evaluation of hazard and seismic risk

NASA Astrophysics Data System (ADS)

Marmureanu, Gheorghe; Marmureanu, Alexandru; Ortanza Cioflan, Carmen; Manea, Elena-Florinela

2015-04-01

Two methods are commonly used for seismic hazard assessment: probabilistic (PSHA) and deterministic(DSHA) seismic hazard analysis.Selection of a ground motion for engineering design requires a clear understanding of seismic hazard and risk among stakeholders, seismologists and engineers. What is wrong with traditional PSHA or DSHA ? PSHA common used in engineering is using four assumptions developed by Cornell in 1968:(1)-Constant-in-time average occurrence rate of earthquakes; (2)-Single point source; (3).Variability of ground motion at a site is independent;(4)-Poisson(or "memory - less") behavior of earthquake occurrences. It is a probabilistic method and "when the causality dies, its place is taken by probability, prestigious term meant to define the inability of us to predict the course of nature"(Nils Bohr). DSHA method was used for the original design of Fukushima Daichii, but Japanese authorities moved to probabilistic assessment methods and the probability of exceeding of the design basis acceleration was expected to be 10-4-10-6 . It was exceeded and it was a violation of the principles of deterministic hazard analysis (ignoring historical events)(Klügel,J,U, EGU,2014, ISSO). PSHA was developed from mathematical statistics and is not based on earthquake science(invalid physical models- point source and Poisson distribution; invalid mathematics; misinterpretation of annual probability of exceeding or return period etc.) and become a pure numerical "creation" (Wang, PAGEOPH.168(2011),11-25). An uncertainty which is a key component for seismic hazard assessment including both PSHA and DSHA is the ground motion attenuation relationship or the so-called ground motion prediction equation (GMPE) which describes a relationship between a ground motion parameter (i.e., PGA,MMI etc.), earthquake magnitude M, source to site distance R, and an uncertainty. So far, no one is taking into consideration strong nonlinear behavior of soils during of strong earthquakes. But, how many cities, villages, metropolitan areas etc. in seismic regions are constructed on rock? Most of them are located on soil deposits? A soil is of basic type sand or gravel (termed coarse soils), silt or clay (termed fine soils) etc. The effect on nonlinearity is very large. For example, if we maintain the same spectral amplification factor (SAF=5.8942) as for relatively strong earthquake on May 3,1990(MW=6.4),then at Bacǎu seismic station for Vrancea earthquake on May 30,1990 (MW =6.9) the peak acceleration has to be a*max =0.154g and the actual recorded was only, amax =0.135g(-14.16%). Also, for Vrancea earthquake on August 30,1986(MW=7.1),the peak acceleration has to be a*max = 0.107g instead of real value recorded of 0.0736 g(- 45.57%). There are many data for more than 60 seismic stations. There is a strong nonlinear dependence of SAF with earthquake magnitude in each site. The authors are coming with an alternative approach called "real spectral amplification factors" instead of GMPE for all extra-Carpathian area where all cities and villages are located on soil deposits. Key words: Probabilistic Seismic Hazard; Uncertainties; Nonlinear seismology; Spectral amplification factors(SAF).

Can North Korean Nuclear Explosions Stir Baekdu (Changbai) Volcano to be Erupted?

NASA Astrophysics Data System (ADS)

Hong, T. K.; Choi, E.; Park, S.; Shin, J. S.

2015-12-01

Potential volcanic eruption in Mt. Baekdu (Changbai) hasbeen a long-lasting concern in the far-eastern Asia.There were several explosive eruptions historically. Themost recent eruption was made in 1903. The eruption in969 is believed to be the most violent with volcanicexplosivity index of 7. The volcano is located in ~130 kmaway from the North Korean nuclear explosion test sitewhere three moderate-size nuclear explosions withmagnitudes of 4.3, 4.7 and 5.1 were conducted in 2006,2009 and 2013. There is increasing concern that a largenuclear explosion may trigger volcanic eruption. Seismicwaveforms are subtle to vary with the crustal structure.The strong ground motions generated by a potential largenuclear explosion are difficult to be simulated forvolcanic regions where complex crustal structures areexpected. We calculate the ground motions by hypotheticallarge nuclear explosions using a nuclear-explosion sourcemodel and the seismic waveforms of prior nuclearexplosions. The validity of the method is examined bycomparing the observed and quasi-synthetic seismicwaveforms of prior nuclear explosions. The peak groundaccelerations (PGA) around the volcano are estimated froma PGA attenuation equation that was determined based onseismic waveforms from natural earthquakes. Thehorizontal and vertical PGAs by an M7.0 undergroundnuclear explosion are expected to reach 0.14 and 0.11m/s2 at the volcano, inducing a dynamic stress in themagma chamber. The induced pressure change in the magmachamber is verified by numerical modeling of dynamicstress changes.

Accuracy assessment of high-rate GPS measurements for seismology

NASA Astrophysics Data System (ADS)

Elosegui, P.; Davis, J. L.; Ekström, G.

2007-12-01

Analysis of GPS measurements with a controlled laboratory system, built to simulate the ground motions caused by tectonic earthquakes and other transient geophysical signals such as glacial earthquakes, enables us to assess the technique of high-rate GPS. The root-mean-square (rms) position error of this system when undergoing realistic simulated seismic motions is 0.05~mm, with maximum position errors of 0.1~mm, thus providing "ground truth" GPS displacements. We have acquired an extensive set of high-rate GPS measurements while inducing seismic motions on a GPS antenna mounted on this system with a temporal spectrum similar to real seismic events. We found that, for a particular 15-min-long test event, the rms error of the 1-Hz GPS position estimates was 2.5~mm, with maximum position errors of 10~mm, and the error spectrum of the GPS estimates was approximately flicker noise. These results may however represent a best-case scenario since they were obtained over a short (~10~m) baseline, thereby greatly mitigating baseline-dependent errors, and when the number and distribution of satellites on the sky was good. For example, we have determined that the rms error can increase by a factor of 2--3 as the GPS constellation changes throughout the day, with an average value of 3.5~mm for eight identical, hourly-spaced, consecutive test events. The rms error also increases with increasing baseline, as one would expect, with an average rms error for a ~1400~km baseline of 9~mm. We will present an assessment of the accuracy of high-rate GPS based on these measurements, discuss the implications of this study for seismology, and describe new applications in glaciology.

Another Look at Strong Ground Motion Accelerations and Stress Drop

NASA Astrophysics Data System (ADS)

Baltay, A.; Prieto, G.; Ide, S.; Hanks, T. C.; Beroza, G. C.

2010-12-01

The relationship between earthquake stress drop and ground motion acceleration is central to seismic hazard analysis. We revisit measurements of root-mean-square (RMS) acceleration, arms, using KikNet accelerometer data from Japan. We directly measure RMS and peak acceleration, and estimate both apparent stress and corner frequencies using the empirical Green’s function (eGf) coda method of Baltay et al. [2010]. We predict armsfrom corner frequency and stress drop following McGuire and Hanks [1980] to compare with measurements. The theoretical relationship does a good job of predicting observed arms. We use four earthquake sequences in Japan to investigate the source parameters and accelerations: the 2008 Iwate-Miyagi earthquake; the off-Kamaishi repeating sequence; and the 2004 and 2007 Niigata events. In each data set, we choose events that are nearly co-located so that the path term to any station is constant. Small events are used as empirical Green’s functions to correct for propagation effects. For all sequences, we find that the apparent stress averages ~1 MPa for most events. Corner frequencies are consistent with Mo-1/3 scaling. We find the ratio of stress drop and apparent stress to be 5, consistent with the theoretical derivation of Singh and Ordaz [1994], using a Brune [1970] spectra. armsis theoretically proportional to stress drop and the inverse square root of the corner frequency. We show that this calculation can be used as a proxy for armsobservations from strong motion records, using recent data from the four earthquake sequences mentioned above. Even for the Iwate-Miyagi mainshock, which experienced over 4 g’s of acceleration, we find that apparent stress, stress drop and corner frequency follow expected scaling laws and support self-similarity.

V S30, slope, H 800 and f 0: performance of various site-condition proxies in reducing ground-motion aleatory variability and predicting nonlinear site response

NASA Astrophysics Data System (ADS)

Derras, Boumédiène; Bard, Pierre-Yves; Cotton, Fabrice

2017-09-01

The aim of this paper is to investigate the ability of various site-condition proxies (SCPs) to reduce ground-motion aleatory variability and evaluate how SCPs capture nonlinearity site effects. The SCPs used here are time-averaged shear-wave velocity in the top 30 m ( V S30), the topographical slope (slope), the fundamental resonance frequency ( f 0) and the depth beyond which V s exceeds 800 m/s ( H 800). We considered first the performance of each SCP taken alone and then the combined performance of the 6 SCP pairs [ V S30- f 0], [ V S30- H 800], [ f 0-slope], [ H 800-slope], [ V S30-slope] and [ f 0- H 800]. This analysis is performed using a neural network approach including a random effect applied on a KiK-net subset for derivation of ground-motion prediction equations setting the relationship between various ground-motion parameters such as peak ground acceleration, peak ground velocity and pseudo-spectral acceleration PSA ( T), and M w, R JB, focal depth and SCPs. While the choice of SCP is found to have almost no impact on the median ground-motion prediction, it does impact the level of aleatory uncertainty. V S30 is found to perform the best of single proxies at short periods ( T < 0.6 s), while f 0 and H 800 perform better at longer periods; considering SCP pairs leads to significant improvements, with particular emphasis on [ V S30- H 800] and [ f 0-slope] pairs. The results also indicate significant nonlinearity on the site terms for soft sites and that the most relevant loading parameter for characterising nonlinear site response is the "stiff" spectral ordinate at the considered period.[Figure not available: see fulltext.

Expectable Earthquakes and their ground motions in the Van Norman Reservoirs Area

USGS Publications Warehouse

Wesson, R.L.; Page, R.A.; Boore, D.M.; Yerkes, R.F.

1974-01-01

The upper and lower Van Norman dams, in northwesternmost San Fernando Valley about 20 mi (32 km) northwest of downtown Los Angeles, were severely damaged during the 1971 San Fernando earthquake. An investigation of the geologic-seismologic setting of the Van Norman area indicates that an earthquake of at least M 7.7 may be expected in the Van Norman area. The expectable transitory effects in the Van Norman area of such an earthquake are as follows: peak horizontal acceleration of at least 1.15 g, peak velocity of displacement of 4.43 ft/sec (135 cm/sec), peak displacement of 2.3 ft (70 cm), and duration of shaking at accelerations greater than 0.05 g, 40 sec. A great earthquake (M 8+) on the San Andreas fault, 25 mi distant, also is expectable. Transitory effects in the Van Norman area from such an earthquake are estimated as follows: peak horizontal acceleration of 0.5 g, peak velocity of 1.97 ft/sec (60 cm/sec), displacement of 1.31 ft (40 cm), and duration of shaking at accelerations greater than 0.05 g, 80 sec. The permanent effects of the expectable local earthquake could include simultaneous fault movement at the lower damsite, the upper damsite, and the site proposed for a replacement dam halfway between the upper and lower dams. The maximum differential displacements due to such movements are estimated at 16.4 ft (5 m) at the lower damsite and about 9.6 ft (2.93 m) at the upper and proposed damsites. The 1971 San Fernando earthquake (M 6?) was accompanied by the most intense ground motions ever recorded instrumentally for a natural earthquake. At the lower Van Norman dam, horizontal accelerations exceeded 0.6 g, and shaking greater than 0.25 g lasted for about 13 see; at Pacoima dam, 6 mi (10 km) northeast of the lower dam, high-frequency peak horizontal accelerations of 1.25 g were recorded in two directions, and shaking greater than 0.25 g lasted for about 7 sec. Permanent effects of the earthquake include slope failures in the embankments of the upper and lower Van Norman dams, rupturing of the ground surface by faulting along parts of the zone of old faults that extends easterly through the reservoir area and across the northern part of the valley, folding or arching of the ground surface, and differential horizontal displacement of the terrane north and south of the fault zone. Although a zone of old faults extends through the reservoir area, the 1971 surface ruptures apparently did not; however, arching and horizontal displacements caused small relative displacements of the abutment areas of each of the three damsites. The 1971 arching coincided with preexisting topographic highs, and the surface ruptures coincided with eroded fault scarps and a buried ground-water impediment formed by pre-1971 faulting in young valley fill. This coincidence with evidence of past deformation indicates that the 1971 deformations were the result of a continuing geologic process that is expected to produce similar deformations during future events. The 1971 San Fernando earthquake probably was not the largest that has occurred in this area during the last approximately 200 years, as indicated by a buried fault like scarp about 200 years old that is higher than, and aligned with, 1971 fault scarps. In addition, the San Fernando zone of 1971 ruptures is part of a regional tectonic system that includes the San Andreas and associated faults; one of these, the White Wolf fault north of the San Andreas, is symmetrical in structural attitude with the San Fernando zone and ruptured the ground surface during the 1952 Kern County earthquake (M 7.7). Other large earthquakes associated with surface rupturing on faults of this system include the 1857 Fort Tejon earthquake (M 8+) and possibly the 1852 Big Pine earthquake. Several other historic earthquakes in this general area are not known to be associated with surface ruptures, but were large enough to cause damage in the northern San Fernando Valley. The Van Norman rese

iShake: Mobile Phones as Seismic Sensors (Invited)

NASA Astrophysics Data System (ADS)

Dashti, S.; Reilly, J.; Bray, J. D.; Bayen, A. M.; Glaser, S. D.; Mari, E.

2010-12-01

Emergency responders must “see” the effects of an earthquake clearly and rapidly so that they can respond effectively to the damage it has produced. Great strides have been made recently in developing methodologies that deliver rapid and accurate post-earthquake information. However, shortcomings still exist. The iShake project is an innovative use of cell phones and information technology to bridge the gap between the high quality, but sparse, ground motion instrument data that are used to help develop ShakeMap and the low quality, but large quantity, human observational data collected to construct a “Did You Feel It?” (DYFI)-based map. Rather than using people as measurement “devices” as is being done through DYFI, the iShake project is using their cell phones to measure ground motion intensity parameters and automatically deliver the data to the U.S. Geological Survey (USGS) for processing and dissemination. In this participatory sensing paradigm, quantitative shaking data from numerous cellular phones will enable the USGS to produce shaking intensity maps more accurately than presently possible. The phone sensor, however, is an imperfect device with performance variations among phones of a given model as well as between models. The sensor is the entire phone, not just the micro-machined transducer inside. A series of 1-D and 3-D shaking table tests were performed at UC San Diego and UC Berkeley, respectively, to evaluate the performance of a class of cell phones. In these tests, seven iPhones and iPod Touch devices that were mounted at different orientations were subjected to 124 earthquake ground motions to characterize their response and reliability as seismic sensors. The testing also provided insight into the seismic response of unsecured and falling instruments. The cell phones measured seismic parameters such as peak ground acceleration (PGA), peak ground velocity (PGV), peak ground displacement (PGD), and 5% damped spectral accelerations well. In general, iPhone and iPod Touch sensors slightly over-estimated ground motion energy (i.e., Arias Intensity, Ia). However, the mean acceleration response spectrum of the seven iPhones compared remarkably well with that of the reference high quality accelerometers. The error in the recorded intensity parameters was dependent on the characteristics of the input ground motion, particularly its PGA and Ia, and increased for stronger motions. The use of a high-friction device cover (e.g., rubber iPhone covers) on unsecured phones yielded substantially improved data by minimizing independent phone movement. Useful information on the ground motion characteristics was even extracted from unsecured phones during intense shaking events. The insight gained from these experiments is valuable in distilling information from a large number of imperfect signals from phones that may not be rigidly connected to the ground. With these ubiquitous measurement devices, a more accurate and rapid portrayal of the damage distribution during an earthquake can be provided to emergency responders and to the public.

Peak ground motion predictions with empirical site factors using Taiwan Strong Motion Network recordings

NASA Astrophysics Data System (ADS)

Chung, Jen-Kuang

2013-09-01

A stochastic method called the random vibration theory (Boore, 1983) has been used to estimate the peak ground motions caused by shallow moderate-to-large earthquakes in the Taiwan area. Adopting Brune's ω-square source spectrum, attenuation models for PGA and PGV were derived from path-dependent parameters which were empirically modeled from about one thousand accelerograms recorded at reference sites mostly located in a mountain area and which have been recognized as rock sites without soil amplification. Consequently, the predicted horizontal peak ground motions at the reference sites, are generally comparable to these observed. A total number of 11,915 accelerograms recorded from 735 free-field stations of the Taiwan Strong Motion Network (TSMN) were used to estimate the site factors by taking the motions from the predictive models as references. Results from soil sites reveal site amplification factors of approximately 2.0 ~ 3.5 for PGA and about 1.3 ~ 2.6 for PGV. Finally, as a result of amplitude corrections with those empirical site factors, about 75% of analyzed earthquakes are well constrained in ground motion predictions, having average misfits ranging from 0.30 to 0.50. In addition, two simple indices, R 0.57 and R 0.38, are proposed in this study to evaluate the validity of intensity map prediction for public information reports. The average percentages of qualified stations for peak acceleration residuals less than R 0.57 and R 0.38 can reach 75% and 54%, respectively, for most earthquakes. Such a performance would be good enough to produce a faithful intensity map for a moderate scenario event in the Taiwan region.

Source characterization of underground explosions from hydrodynamic-to-elastic coupling simulations

NASA Astrophysics Data System (ADS)

Chiang, A.; Pitarka, A.; Ford, S. R.; Ezzedine, S. M.; Vorobiev, O.

2017-12-01

A major improvement in ground motion simulation capabilities for underground explosion monitoring during the first phase of the Source Physics Experiment (SPE) is the development of a wave propagation solver that can propagate explosion generated non-linear near field ground motions to the far-field. The calculation is done using a hybrid modeling approach with a one-way hydrodynamic-to-elastic coupling in three dimensions where near-field motions are computed using GEODYN-L, a Lagrangian hydrodynamics code, and then passed to WPP, an elastic finite-difference code for seismic waveform modeling. The advancement in ground motion simulation capabilities gives us the opportunity to assess moment tensor inversion of a realistic volumetric source with near-field effects in a controlled setting, where we can evaluate the recovered source properties as a function of modeling parameters (i.e. velocity model) and can provide insights into previous source studies on SPE Phase I chemical shots and other historical nuclear explosions. For example the moment tensor inversion of far-field SPE seismic data demonstrated while vertical motions are well-modeled using existing velocity models large misfits still persist in predicting tangential shear wave motions from explosions. One possible explanation we can explore is errors and uncertainties from the underlying Earth model. Here we investigate the recovered moment tensor solution, particularly on the non-volumetric component, by inverting far-field ground motions simulated from physics-based explosion source models in fractured material, where the physics-based source models are based on the modeling of SPE-4P, SPE-5 and SPE-6 near-field data. The hybrid modeling approach provides new prospects in modeling explosion source and understanding the uncertainties associated with it.

Reconciling the Dawn-Dusk Asymmetry in Mercury’s Exosphere with the Micrometeoroid Impact Directionality

NASA Astrophysics Data System (ADS)

Pokorný, Petr; Sarantos, Menelaos; Janches, Diego

2017-06-01

Combining dynamical models of dust from Jupiter-family comets and Halley-type comets, we demonstrate that the seasonal variation of the dust/meteoroid environment at Mercury is responsible for producing the dawn-dusk asymmetry in Mercury’s exosphere observed by the MESSENGER spacecraft. Our latest models, calibrated recently from ground-based and space-borne measurements, provide unprecedented statistics that enable us to study the longitudinal and latitudinal distribution of meteoroids impacting Mercury’s surface. We predict that the micrometeoroid impact vaporization source is expected to undergo significant motion on Mercury’s surface toward the nightside during Mercury’s approach to aphelion and toward the dayside when the planet is approaching the Sun.

Gravitational Wave Astrophysics: Opening the New Frontier

NASA Technical Reports Server (NTRS)

Centrella, Joan

2011-01-01

The gravitational wave window onto the universe is expected to open in 5 years, when ground-based detectors make the first detections in the high-frequency regime. Gravitational waves are ripples in spacetime produced by the motions of massive objects such as black holes and neutron stars. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources such as masses, spins, luminosity distances, and orbital parameters through dense, obscured regions across cosmic time. This article explores gravitational waves as cosmic messengers, highlighting key sources, detection methods, and the astrophysical payoffs across the gravitational wave spectrum. Keywords: Gravitational wave astrophysics; gravitational radiation; gravitational wave detectors; black holes.

Re-Thinking the Use of the OML Model in Electric-Sail Development

NASA Technical Reports Server (NTRS)

Stone, Nobie H.

2016-01-01

The Orbit Motion Limited (OML) model commonly forms the basis for calculations made to determine the effect of the long, biased wires of an Electric Sail on solar wind protons and electrons (which determines the thrust generated and the required operating power). A new analysis of the results of previously conducted ground-based experimental studies of spacecraft-space plasma interactions indicate that the expected thrust created by deflected solar wind protons and the current of collected solar wind electrons could be considerably higher than the OML model would suggest. Herein the experimental analysis will be summarized and the assumptions and approximations required to derive the OML equation-and the limitations they impose-will be considered.

Reconciling the Dawn-Dusk Asymmetry in Mercury's Exosphere with the Micrometeoroid Impact Directionality

NASA Technical Reports Server (NTRS)

Pokorny, Petr; Sarantos, Menelaos; Janches, Diego

2017-01-01

Combining dynamical models of dust from Jupiter-family comets and Halley-type comets, we demonstrate that the seasonal variation of the dust/meteoroid environment at Mercury is responsible for producing the dawn-dusk asymmetry in Mercury's exosphere observed by the MESSENGER spacecraft. Our latest models, calibrated recently from ground-based and space-borne measurements, provide unprecedented statistics that enable us to study the longitudinal and latitudinal distribution of meteoroids impacting Mercury's surface. We predict that the micrometeoroid impact vaporization source is expected to undergo significant motion on Mercury's surface toward the nightside during Mercury's approach to aphelion and toward the dayside when the planet is approaching the Sun.

Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions

USGS Publications Warehouse

Rezaeian, Sanaz; Bozorgnia, Yousef; Idriss, I.M.; Campbell, Kenneth; Abrahamson, Norman; Silva, Walter

2012-01-01

Ground motion prediction equations (GMPEs) for elastic response spectra, including the Next Generation Attenuation (NGA) models, are typically developed at a 5% viscous damping ratio. In reality, however, structural and non-structural systems can have damping ratios other than 5%, depending on various factors such as structural types, construction materials, level of ground motion excitations, among others. This report provides the findings of a comprehensive study to develop a new model for a Damping Scaling Factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE to spectral ordinates with damping ratios between 0.5 to 30%. Using the updated, 2011 version of the NGA database of ground motions recorded in worldwide shallow crustal earthquakes in active tectonic regions (i.e., the NGA-West2 database), dependencies of the DSF on variables including damping ratio, spectral period, moment magnitude, source-to-site distance, duration, and local site conditions are examined. The strong influence of duration is captured by inclusion of both magnitude and distance in the DSF model. Site conditions are found to have less significant influence on DSF and are not included in the model. The proposed model for DSF provides functional forms for the median value and the logarithmic standard deviation of DSF. This model is heteroscedastic, where the variance is a function of the damping ratio. Damping Scaling Factor models are developed for the “average” horizontal ground motion components, i.e., RotD50 and GMRotI50, as well as the vertical component of ground motion.

Observed ground-motion variabilities and implication for source properties

NASA Astrophysics Data System (ADS)

Cotton, F.; Bora, S. S.; Bindi, D.; Specht, S.; Drouet, S.; Derras, B.; Pina-Valdes, J.

2016-12-01

One of the key challenges of seismology is to be able to calibrate and analyse the physical factors that control earthquake and ground-motion variabilities. Within the framework of empirical ground-motion prediction equation (GMPE) developments, ground-motions residuals (differences between recorded ground motions and the values predicted by a GMPE) are computed. The exponential growth of seismological near-field records and modern regression algorithms allow to decompose these residuals into between-event and a within-event residual components. The between-event term quantify all the residual effects of the source (e.g. stress-drops) which are not accounted by magnitude term as the only source parameter of the model. Between-event residuals provide a new and rather robust way to analyse the physical factors that control earthquake source properties and associated variabilities. We first will show the correlation between classical stress-drops and between-event residuals. We will also explain why between-event residuals may be a more robust way (compared to classical stress-drop analysis) to analyse earthquake source-properties. We will finally calibrate between-events variabilities using recent high-quality global accelerometric datasets (NGA-West 2, RESORCE) and datasets from recent earthquakes sequences (Aquila, Iquique, Kunamoto). The obtained between-events variabilities will be used to evaluate the variability of earthquake stress-drops but also the variability of source properties which cannot be explained by a classical Brune stress-drop variations. We will finally use the between-event residual analysis to discuss regional variations of source properties, differences between aftershocks and mainshocks and potential magnitude dependencies of source characteristics.

A generalization of the double-corner-frequency source spectral model and its use in the SCEC BBP validation exercise

USGS Publications Warehouse

Boore, David M.; Di Alessandro, Carola; Abrahamson, Norman A.

2014-01-01

The stochastic method of simulating ground motions requires the specification of the shape and scaling with magnitude of the source spectrum. The spectral models commonly used are either single-corner-frequency or double-corner-frequency models, but the latter have no flexibility to vary the high-frequency spectral levels for a specified seismic moment. Two generalized double-corner-frequency ω2 source spectral models are introduced, one in which two spectra are multiplied together, and another where they are added. Both models have a low-frequency dependence controlled by the seismic moment, and a high-frequency spectral level controlled by the seismic moment and a stress parameter. A wide range of spectral shapes can be obtained from these generalized spectral models, which makes them suitable for inversions of data to obtain spectral models that can be used in ground-motion simulations in situations where adequate data are not available for purely empirical determinations of ground motions, as in stable continental regions. As an example of the use of the generalized source spectral models, data from up to 40 stations from seven events, plus response spectra at two distances and two magnitudes from recent ground-motion prediction equations, were inverted to obtain the parameters controlling the spectral shapes, as well as a finite-fault factor that is used in point-source, stochastic-method simulations of ground motion. The fits to the data are comparable to or even better than those from finite-fault simulations, even for sites close to large earthquakes.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

NASA Astrophysics Data System (ADS)

Bowen, S. R.; Nyflot, M. J.; Herrmann, C.; Groh, C. M.; Meyer, J.; Wollenweber, S. D.; Stearns, C. W.; Kinahan, P. E.; Sandison, G. A.

2015-05-01

Effective positron emission tomography / computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [18F]FDG. The lung lesion insert was driven by six different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses, and 2%-2 mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10-20%, treatment planning errors were 5-10%, and treatment delivery errors were 5-30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5-10% in PET/CT imaging, <5% in treatment planning, and <2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study.

PubMed

Bowen, S R; Nyflot, M J; Herrmann, C; Groh, C M; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

2015-05-07

Effective positron emission tomography / computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [(18)F]FDG. The lung lesion insert was driven by six different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses, and 2%-2 mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10-20%, treatment planning errors were 5-10%, and treatment delivery errors were 5-30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5-10% in PET/CT imaging, <5% in treatment planning, and <2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

PubMed Central

Bowen, S R; Nyflot, M J; Hermann, C; Groh, C; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

2015-01-01

Effective positron emission tomography/computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [18F]FDG. The lung lesion insert was driven by 6 different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy (VMAT) were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses (EUD), and 2%-2mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10–20%, treatment planning errors were 5–10%, and treatment delivery errors were 5–30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5–10% in PET/CT imaging, < 5% in treatment planning, and < 2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery. PMID:25884892

Nonlinear Dynamics of a Helicopter Model in Ground Resonance

NASA Technical Reports Server (NTRS)

Tang, D. M.; Dowell, E. H.

1985-01-01

An approximate theoretical method is presented which determined the limit cycle behavior of a helicopter model which has one or two nonlinear dampers. The relationship during unstable ground resonance oscillations between lagging motion of the blades and fuselage motion is discussed. An experiment was carried out on using a helicopter scale model. The experimental results agree with those of the theoretical analysis.

Roosevelt Hot Springs, Utah FORGE Ground Motion Study Report

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

Moore, Joe

Paragon Geophysical contracted Urban Seismic Specialists to conduct A Ground Motion Study, on their Forge 3D project located near in Milford Utah .The test was conducted to measure the effects of the vibrator array on a pipeline owned by Kern River. Testing began November 22nd, and was completed on November 23rd. Demobilizing was completed on November 24, 2017

Geometric figure–ground cues override standard depth from accretion-deletion

PubMed Central

Tanrıkulu, Ömer Dağlar; Froyen, Vicky; Feldman, Jacob; Singh, Manish

2016-01-01

Accretion-deletion is widely considered a decisive cue to surface depth ordering, with the accreting or deleting surface interpreted as behind an adjoining surface. However, Froyen, Feldman, and Singh (2013) have shown that when accretion-deletion occurs on both sides of a contour, accreting-deleting regions can also be perceived as in front and as self-occluding due to rotation in three dimensions. In this study we ask whether geometric figure–ground cues can override the traditional “depth from accretion-deletion” interpretation even when accretion-deletion takes place only on one side of a contour. We used two tasks: a relative-depth task (front/back), and a motion-classification task (translation/rotation). We conducted two experiments, in which texture in only one set of alternating regions was moving; the other set was static. Contrary to the traditional interpretation of accretion-deletion, the moving convex and symmetric regions were perceived as figural and rotating in three dimensions in roughly half of the trials. In the second experiment, giving different motion directions to the moving regions (thereby weakening motion-based grouping) further weakened the traditional accretion-deletion interpretation. Our results show that the standard “depth from accretion-deletion” interpretation is overridden by static geometric cues to figure–ground. Overall, the results demonstrate a rich interaction between accretion-deletion, figure–ground, and structure from motion that is not captured by existing models of depth from motion. PMID:26982528

The case for 6-component ground motion observations in planetary seismology

NASA Astrophysics Data System (ADS)

Joshi, Rakshit; van Driel, Martin; Donner, Stefanie; Nunn, Ceri; Wassermann, Joachim; Igel, Heiner

2017-04-01

The imminent INSIGHT mission will place a single seismic station on Mars to learn more about the structure of the Martian interior. Due to cost and difficulty, only single stations are currently feasible for planetary missions. We show that future single station missions should also measure rotational ground motions, in addition to the classic 3 components of translational motion. The joint, collocated, 6 component (6C) observations offer access to additional information that can otherwise only be obtained through seismic array measurements or are associated with large uncertainties. An example is the access to local phase velocity information from measurements of amplitude ratios of translations and rotations. When surface waves are available, this implies (in principle) that 1D velocity models can be estimated from Love wave dispersion curves. In addition, rotational ground motion observations can distinguish between Love and Rayleigh waves as well as S and P type motions. Wave propagation directions can be estimated by maximizing (or minimizing) coherence between translational and rotational motions. In combination with velocity-depth estimates, locations of seismic sources can be determined from a single station with little or no prior knowledge of the velocity structure. We demonstrate these points with both theoretical and real data examples using the vertical component of motion from ring laser recordings at Wettzell and all components of motion from the ROMY ring near Munich. Finally, we present the current state of technology concerning portable rotation sensors and discuss the relevance to planetary seismology.

Practical guidelines to select and scale earthquake records for nonlinear response history analysis of structures

USGS Publications Warehouse

Kalkan, Erol; Chopra, Anil K.

2010-01-01

Earthquake engineering practice is increasingly using nonlinear response history analysis (RHA) to demonstrate performance of structures. This rigorous method of analysis requires selection and scaling of ground motions appropriate to design hazard levels. Presented herein is a modal-pushover-based scaling (MPS) method to scale ground motions for use in nonlinear RHA of buildings and bridges. In the MPS method, the ground motions are scaled to match (to a specified tolerance) a target value of the inelastic deformation of the first-'mode' inelastic single-degree-of-freedom (SDF) system whose properties are determined by first-'mode' pushover analysis. Appropriate for first-?mode? dominated structures, this approach is extended for structures with significant contributions of higher modes by considering elastic deformation of second-'mode' SDF system in selecting a subset of the scaled ground motions. Based on results presented for two bridges, covering single- and multi-span 'ordinary standard' bridge types, and six buildings, covering low-, mid-, and tall building types in California, the accuracy and efficiency of the MPS procedure are established and its superiority over the ASCE/SEI 7-05 scaling procedure is demonstrated.

Inversion of ground-motion data from a seismometer array for rotation using a modification of Jaeger's method

USGS Publications Warehouse

Chi, Wu-Cheng; Lee, W.H.K.; Aston, J.A.D.; Lin, C.J.; Liu, C.-C.

2011-01-01

We develop a new way to invert 2D translational waveforms using Jaeger's (1969) formula to derive rotational ground motions about one axis and estimate the errors in them using techniques from statistical multivariate analysis. This procedure can be used to derive rotational ground motions and strains using arrayed translational data, thus providing an efficient way to calibrate the performance of rotational sensors. This approach does not require a priori information about the noise level of the translational data and elastic properties of the media. This new procedure also provides estimates of the standard deviations of the derived rotations and strains. In this study, we validated this code using synthetic translational waveforms from a seismic array. The results after the inversion of the synthetics for rotations were almost identical with the results derived using a well-tested inversion procedure by Spudich and Fletcher (2009). This new 2D procedure can be applied three times to obtain the full, three-component rotations. Additional modifications can be implemented to the code in the future to study different features of the rotational ground motions and strains induced by the passage of seismic waves.

The effects of dorso-lumbar motion restriction on the ground reaction force components during running.

PubMed

Morley, Joseph J; Traum, Edward

2016-04-01

The effects of restricting dorso-lumbar spine mobility on ground reaction forces in runners was measured and assessed. A semi-rigid cast was used to restrict spinal motion during running. Subjects ran across a force platform at 3.6 m/s, planting the right foot on the platform. Data was collected from ten running trials with the cast and ten without the cast and analysed. Casted running showed that the initial vertical heel strike maximum was increased (p < .02) and that the anterior-posterior deceleration impulse was increased (p < .01). The maximum vertical ground reaction force was decreased in casted running (p < .01), as was the anterior-posterior acceleration impulse (p < .02). There was a trend for increased medial-lateral impulse in the uncasted state, but this was not statistically significant. Spinal mobility and fascia contribute to load transfer between joints and body segments. Experimentally restricting spinal motion during running results in measurable and repeatable alterations in ground reaction force components. Alterations in load transfer due to decreased spinal motion may be a factor contributing to selected injuries in runners. Copyright © 2015 Elsevier Ltd. All rights reserved.

Response of Pendulums to Translational and Rotational Components of Ground Motion

NASA Astrophysics Data System (ADS)

Graizer, V.; Kalkan, E.

2008-12-01

Dynamic response of most seismological instruments and many engineering structures to ground shaking can be represented via response of a pendulum (single-degree-of-freedom oscillator). Pendulum response is usually simplified by considering the input from uni-axial translational motion only. Complete ground motion however, includes not only translational components but also rotations (tilt and torsion). We consider complete equations of motion for three following types of pendulum: (i) conventional mass-on-rod, (ii) mass- on-spring type, and (iii) inverted (astatic), then their response sensitivities to each component of complex ground motion are examined. Inverted pendulums are used in seismology for more than 100 years, for example, classical Wiechert's horizontal seismograph built around 1905 and still used at some seismological observatories, and recent Guralp's horizontal seismometers CMG-40T and CMG-3T. Inverted pendulums also have significant importance for engineering applications where they are often used to simulate the dynamic response of various structural systems. The results of this study show that a horizontal pendulum similar to a modern accelerometer used in strong motion measurements is practically sensitive to translational motion and tilt only, while inverted pendulum is sensitive not only to translational components, but also to angular accelerations and tilt. For better understanding of the inverted pendulum's dynamic behavior under complex ground excitation, relative contribution of each component of motion on response variants is carefully isolated. The responses of pendulums are calculated in time-domain using close-form solution Duhamel's integral with complex input forcing functions. As compared to a common horizontal pendulum, response of an inverted pendulum is sensitive to acceleration of gravity and vertical acceleration when it reaches the level close to 1.0 g. Gravity effect introduces nonlinearity into the differential equation of motion, and results in shift of the frequency response to lower frequencies. The equations of inverted pendulum represent elastic response of pendulums (as material behavior), with nonlinearity created by time and amplitude dependence of equation coefficients. Sensitivity of inverted pendulum to angular acceleration of tilt is proportional to the length of a pendulum, and should be taken into consideration since it can produce significant effect especially for long pendulums, idealizing for instance, bridge piers, bents, elevated water tanks, telecommunication towers, etc.

Deformations and Rotational Ground Motions Inferred from Downhole Vertical Array Observations

NASA Astrophysics Data System (ADS)

Graizer, V.

2017-12-01

Only few direct reliable measurements of rotational component of strong earthquake ground motions are obtained so far. In the meantime, high quality data recorded at downhole vertical arrays during a number of earthquakes provide an opportunity to calculate deformations based on the differences in ground motions recorded simultaneously at different depths. More than twenty high resolution strong motion downhole vertical arrays were installed in California with primary goal to study site response of different geologic structures to strong motion. Deformation or simple shear strain with the rate γ is the combination of pure shear strain with the rate γ/2 and rotation with the rate of α=γ/2. Deformations and rotations were inferred from downhole array records of the Mw 6.0 Parkfield 2004, the Mw 7.2 Sierra El Mayor (Mexico) 2010, the Mw 6.5 Ferndale area in N. California 2010 and the two smaller earthquakes in California. Highest amplitude of rotation of 0.60E-03 rad was observed at the Eureka array corresponding to ground velocity of 35 cm/s, and highest rotation rate of 0.55E-02 rad/s associated with the S-wave was observed at a close epicentral distance of 4.3 km from the ML 4.2 event in Southern California at the La Cienega array. Large magnitude Sierra El Mayor earthquake produced long duration rotational motions of up to 1.5E-04 rad and 2.05E-03 rad/s associated with shear and surface waves at the El Centro array at closest fault distance of 33.4km. Rotational motions of such levels, especially tilting can have significant effect on structures. High dynamic range well synchronized and properly oriented instrumentation is necessary for reliable calculation of rotations from vertical array data. Data from the dense Treasure Island array near San Francisco demonstrate consistent change of shape of rotational motion with depth and material. In the frequency range of 1-15 Hz Fourier amplitude spectrum of vertical ground velocity is similar to the scaled tilt spectrum. Amplitudes of rotations at the site depend upon the size of the base and usually decrease with depth. They are also amplified by soft material. Earthquake data used in this study were downloaded from the Center for Engineering Strong Motion Data at http://www.strongmotioncenter.org/.

Probabilistic seismic hazard analyses for ground motions and fault displacement at Yucca Mountain, Nevada

USGS Publications Warehouse

Stepp, J.C.; Wong, I.; Whitney, J.; Quittmeyer, R.; Abrahamson, N.; Toro, G.; Young, S.R.; Coppersmith, K.; Savy, J.; Sullivan, T.

2001-01-01

Probabilistic seismic hazard analyses were conducted to estimate both ground motion and fault displacement hazards at the potential geologic repository for spent nuclear fuel and high-level radioactive waste at Yucca Mountain, Nevada. The study is believed to be the largest and most comprehensive analyses ever conducted for ground-shaking hazard and is a first-of-a-kind assessment of probabilistic fault displacement hazard. The major emphasis of the study was on the quantification of epistemic uncertainty. Six teams of three experts performed seismic source and fault displacement evaluations, and seven individual experts provided ground motion evaluations. State-of-the-practice expert elicitation processes involving structured workshops, consensus identification of parameters and issues to be evaluated, common sharing of data and information, and open exchanges about the basis for preliminary interpretations were implemented. Ground-shaking hazard was computed for a hypothetical rock outcrop at -300 m, the depth of the potential waste emplacement drifts, at the designated design annual exceedance probabilities of 10-3 and 10-4. The fault displacement hazard was calculated at the design annual exceedance probabilities of 10-4 and 10-5.

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.

Ground motions at the outermost limits of seismically triggered landslides

USGS Publications Warehouse

Jibson, Randall W.; Harp, Edwin L.

2016-01-01

Over the last few decades, we and our colleagues have conducted field investigations in which we mapped the outermost limits of triggered landslides in four earthquakes: 1987 Whittier Narrows, California (M 5.9), 1987 Superstition Hills, California (M 6.5), 1994 Northridge, California (M 6.7), and 2011 Mineral, Virginia (M 5.8). In an additional two earthquakes, 1976 Guatemala (M 7.5) and 1983 Coalinga, California (M 6.5), we determined limits using high‐resolution aerial‐photographic interpretation in conjunction with more limited ground investigation. Limits in these earthquakes were defined by the locations of the very smallest failures (<1  m3) from the most susceptible slopes that can be identified positively as having been triggered by earthquake shaking. Because we and our colleagues conducted all of these investigations, consistent methodology and criteria were used in determining limits. In the six earthquakes examined, we correlated the outermost landslide limits with peak ground accelerations (PGAs) from ShakeMap models of each earthquake. For the four earthquakes studied by field investigation, the minimum PGA values associated with farthest landslide limits ranged from 0.02g to 0.08g. The range for the two earthquakes investigated using aerial‐photographic interpretations was 0.05–0.11g. Although PGA values at landslide limits depend on several factors, including material strength, topographic amplification, and hydrologic conditions, these values provide an empirically useful lower limiting range of PGA needed to trigger the smallest failures on very susceptible slopes. In a well‐recorded earthquake, this PGA range can be used to identify an outer boundary within which we might expect to find landsliding; in earthquakes that are not well recorded, mapping the outermost landslide limits provides a useful clue about ground‐motion levels at the mapped limits.

Trampoline effect in extreme ground motion.

PubMed

Aoi, Shin; Kunugi, Takashi; Fujiwara, Hiroyuki

2008-10-31

In earthquake hazard assessment studies, the focus is usually on horizontal ground motion. However, records from the 14 June 2008 Iwate-Miyagi earthquake in Japan, a crustal event with a moment magnitude of 6.9, revealed an unprecedented vertical surface acceleration of nearly four times gravity, more than twice its horizontal counterpart. The vertical acceleration was distinctly asymmetric; the waveform envelope was about 1.6 times as large in the upward direction as in the downward direction, which is not explained by existing models of the soil response. We present a simple model of a mass bouncing on a trampoline to account for this asymmetry and the large vertical amplitude. The finding of a hitherto-unknown mode of strong ground motion may prompt major progress in near-source shaking assessments.

Rainfall, ground-water flow, and seasonal movement at Minor Creek landslide, northwestern California: physical interpretation of empirical relations

USGS Publications Warehouse

Iverson, R.M.; Major, J.J.

1987-01-01

We present data on rainfall, ground-water flow, and repetitive seasonal motion that occurred from 1982 to 1985 at Minor Creek landslide in northwestern Californa, and we interpret these data in the context of physically based theories. We find that landslide motion is closely regulated by the direction and magnitude of near-surface hydraulic gradients and by waves of pore pressure caused by intermittent rainfall. Hummocky topography that results from slope instability may cause ground-water flow that perpetuates instability. -from Authors

Processing of strong-motion accelerograms: Needs, options and consequences

USGS Publications Warehouse

Boore, D.M.; Bommer, J.J.

2005-01-01

Recordings from strong-motion accelerographs are of fundamental importance in earthquake engineering, forming the basis for all characterizations of ground shaking employed for seismic design. The recordings, particularly those from analog instruments, invariably contain noise that can mask and distort the ground-motion signal at both high and low frequencies. For any application of recorded accelerograms in engineering seismology or earthquake engineering, it is important to identify the presence of this noise in the digitized time-history and its influence on the parameters that are to be derived from the records. If the parameters of interest are affected by noise then appropriate processing needs to be applied to the records, although it must be accepted from the outset that it is generally not possible to recover the actual ground motion over a wide range of frequencies. There are many schemes available for processing strong-motion data and it is important to be aware of the merits and pitfalls associated with each option. Equally important is to appreciate the effects of the procedures on the records in order to avoid errors in the interpretation and use of the results. Options for processing strong-motion accelerograms are presented, discussed and evaluated from the perspective of engineering application. ?? 2004 Elsevier Ltd. All rights reserved.

Detection of ground motions using high-rate GPS time-series

NASA Astrophysics Data System (ADS)

Psimoulis, Panos A.; Houlié, Nicolas; Habboub, Mohammed; Michel, Clotaire; Rothacher, Markus

2018-05-01

Monitoring surface deformation in real-time help at planning and protecting infrastructures and populations, manage sensitive production (i.e. SEVESO-type) and mitigate long-term consequences of modifications implemented. We present RT-SHAKE, an algorithm developed to detect ground motions associated with landslides, sub-surface collapses, subsidences, earthquakes or rock falls. RT-SHAKE detects first transient changes in individual GPS time series before investigating for spatial correlation(s) of observations made at neighbouring GPS sites and eventually issue a motion warning. In order to assess our algorithm on fast (seconds to minute), large (from 1 cm to meters) and spatially consistent surface motions, we use the 1 Hz GEONET GNSS network data of the Tohoku-Oki MW9.0 2011 as a test scenario. We show the delay of detection of seismic wave arrival by GPS records is of ˜10 seconds with respect to an identical analysis based on strong-motion data and this time delay depends on the level of the time-variable noise. Nevertheless, based on the analysis of the GPS network noise level and ground motion stochastic model, we show that RT-SHAKE can narrow the range of earthquake magnitude, by setting a lower threshold of detected earthquakes to MW6.5-7, if associated with a real-time automatic earthquake location system.

Evaluation of motion artifact metrics for coronary CT angiography.

PubMed

Ma, Hongfeng; Gros, Eric; Szabo, Aniko; Baginski, Scott G; Laste, Zachary R; Kulkarni, Naveen M; Okerlund, Darin; Schmidt, Taly G

2018-02-01

This study quantified the performance of coronary artery motion artifact metrics relative to human observer ratings. Motion artifact metrics have been used as part of motion correction and best-phase selection algorithms for Coronary Computed Tomography Angiography (CCTA). However, the lack of ground truth makes it difficult to validate how well the metrics quantify the level of motion artifact. This study investigated five motion artifact metrics, including two novel metrics, using a dynamic phantom, clinical CCTA images, and an observer study that provided ground-truth motion artifact scores from a series of pairwise comparisons. Five motion artifact metrics were calculated for the coronary artery regions on both phantom and clinical CCTA images: positivity, entropy, normalized circularity, Fold Overlap Ratio (FOR), and Low-Intensity Region Score (LIRS). CT images were acquired of a dynamic cardiac phantom that simulated cardiac motion and contained six iodine-filled vessels of varying diameter and with regions of soft plaque and calcifications. Scans were repeated with different gantry start angles. Images were reconstructed at five phases of the motion cycle. Clinical images were acquired from 14 CCTA exams with patient heart rates ranging from 52 to 82 bpm. The vessel and shading artifacts were manually segmented by three readers and combined to create ground-truth artifact regions. Motion artifact levels were also assessed by readers using a pairwise comparison method to establish a ground-truth reader score. The Kendall's Tau coefficients were calculated to evaluate the statistical agreement in ranking between the motion artifacts metrics and reader scores. Linear regression between the reader scores and the metrics was also performed. On phantom images, the Kendall's Tau coefficients of the five motion artifact metrics were 0.50 (normalized circularity), 0.35 (entropy), 0.82 (positivity), 0.77 (FOR), 0.77(LIRS), where higher Kendall's Tau signifies higher agreement. The FOR, LIRS, and transformed positivity (the fourth root of the positivity) were further evaluated in the study of clinical images. The Kendall's Tau coefficients of the selected metrics were 0.59 (FOR), 0.53 (LIRS), and 0.21 (Transformed positivity). In the study of clinical data, a Motion Artifact Score, defined as the product of FOR and LIRS metrics, further improved agreement with reader scores, with a Kendall's Tau coefficient of 0.65. The metrics of FOR, LIRS, and the product of the two metrics provided the highest agreement in motion artifact ranking when compared to the readers, and the highest linear correlation to the reader scores. The validated motion artifact metrics may be useful for developing and evaluating methods to reduce motion in Coronary Computed Tomography Angiography (CCTA) images. © 2017 American Association of Physicists in Medicine.

Strong motions observed by K-NET and KiK-net during the 2016 Kumamoto earthquake sequence

NASA Astrophysics Data System (ADS)

Suzuki, Wataru; Aoi, Shin; Kunugi, Takashi; Kubo, Hisahiko; Morikawa, Nobuyuki; Nakamura, Hiromitsu; Kimura, Takeshi; Fujiwara, Hiroyuki

2017-01-01

The nationwide strong-motion seismograph network of K-NET and KiK-net in Japan successfully recorded the strong ground motions of the 2016 Kumamoto earthquake sequence, which show the several notable characteristics. For the first large earthquake with a JMA magnitude of 6.5 (21:26, April 14, 2016, JST), the large strong motions are concentrated near the epicenter and the strong-motion attenuations are well predicted by the empirical relation for crustal earthquakes with a moment magnitude of 6.1. For the largest earthquake of the sequence with a JMA magnitude of 7.3 (01:25, April 16, 2016, JST), the large peak ground accelerations and velocities extend from the epicentral area to the northeast direction. The attenuation feature of peak ground accelerations generally follows the empirical relation, whereas that for velocities deviates from the empirical relation for stations with the epicentral distance of greater than 200 km, which can be attributed to the large Love wave having a dominant period around 10 s. The large accelerations were observed at stations even in Oita region, more than 70 km northeast from the epicenter. They are attributed to the local induced earthquake in Oita region, whose moment magnitude is estimated to be 5.5 by matching the amplitudes of the corresponding phases with the empirical attenuation relation. The real-time strong-motion observation has a potential for contributing to the mitigation of the ongoing earthquake disasters. We test a methodology to forecast the regions to be exposed to the large shaking in real time, which has been developed based on the fact that the neighboring stations are already shaken, for the largest event of the Kumamoto earthquakes, and demonstrate that it is simple but effective to quickly make warning. We also shows that the interpolation of the strong motions in real time is feasible, which will be utilized for the real-time forecast of ground motions based on the observed shakings.[Figure not available: see fulltext.

Color Improves Speed of Processing But Not Perception in a Motion Illusion

PubMed Central

Perry, Carolyn J.; Fallah, Mazyar

2012-01-01

When two superimposed surfaces of dots move in different directions, the perceived directions are shifted away from each other. This perceptual illusion has been termed direction repulsion and is thought to be due to mutual inhibition between the representations of the two directions. It has further been shown that a speed difference between the two surfaces attenuates direction repulsion. As speed and direction are both necessary components of representing motion, the reduction in direction repulsion can be attributed to the additional motion information strengthening the representations of the two directions and thus reducing the mutual inhibition. We tested whether bottom-up attention and top-down task demands, in the form of color differences between the two surfaces, would also enhance motion processing, reducing direction repulsion. We found that the addition of color differences did not improve direction discrimination and reduce direction repulsion. However, we did find that adding a color difference improved performance on the task. We hypothesized that the performance differences were due to the limited presentation time of the stimuli. We tested this in a follow-up experiment where we varied the time of presentation to determine the duration needed to successfully perform the task with and without the color difference. As we expected, color segmentation reduced the amount of time needed to process and encode both directions of motion. Thus we find a dissociation between the effects of attention on the speed of processing and conscious perception of direction. We propose four potential mechanisms wherein color speeds figure-ground segmentation of an object, attentional switching between objects, direction discrimination and/or the accumulation of motion information for decision-making, without affecting conscious perception of the direction. Potential neural bases are also explored. PMID:22479255

Color improves speed of processing but not perception in a motion illusion.

PubMed

Perry, Carolyn J; Fallah, Mazyar

2012-01-01

When two superimposed surfaces of dots move in different directions, the perceived directions are shifted away from each other. This perceptual illusion has been termed direction repulsion and is thought to be due to mutual inhibition between the representations of the two directions. It has further been shown that a speed difference between the two surfaces attenuates direction repulsion. As speed and direction are both necessary components of representing motion, the reduction in direction repulsion can be attributed to the additional motion information strengthening the representations of the two directions and thus reducing the mutual inhibition. We tested whether bottom-up attention and top-down task demands, in the form of color differences between the two surfaces, would also enhance motion processing, reducing direction repulsion. We found that the addition of color differences did not improve direction discrimination and reduce direction repulsion. However, we did find that adding a color difference improved performance on the task. We hypothesized that the performance differences were due to the limited presentation time of the stimuli. We tested this in a follow-up experiment where we varied the time of presentation to determine the duration needed to successfully perform the task with and without the color difference. As we expected, color segmentation reduced the amount of time needed to process and encode both directions of motion. Thus we find a dissociation between the effects of attention on the speed of processing and conscious perception of direction. We propose four potential mechanisms wherein color speeds figure-ground segmentation of an object, attentional switching between objects, direction discrimination and/or the accumulation of motion information for decision-making, without affecting conscious perception of the direction. Potential neural bases are also explored.

18 CFR 385.716 - Reopening (Rule 716).

Code of Federal Regulations, 2010 CFR

2010-04-01

... purpose of taking additional evidence. (b) By motion. (1) Any participant may file a motion to reopen the record. (2) Any motion to reopen must set forth clearly the facts sought to be proven and the reasons claimed to constitute grounds for reopening. (3) A participant who does not file an answer to any motion...

Modeling of induced seismicity and ground vibrations associated with geologic CO 2 storage, and assessing their effects on surface structures and human perception

DOE PAGES

Rutqvist, Jonny; Cappa, Frédéric; Rinaldi, Antonio P.; ...

2014-05-01

In this paper, we present model simulations of ground motions caused by CO 2 -injection-induced fault reactivation and analyze the results in terms of the potential for damage to ground surface structures and nuisance to the local human population. It is an integrated analysis from cause to consequence, including the whole chain of processes starting from earthquake inception in the subsurface, wave propagation toward the ground surface, and assessment of the consequences of ground vibration. For a small magnitude (M w =3) event at a hypocenter depth of about 1000m, we first used the simulated ground-motion wave train in anmore » inverse analysis to estimate source parameters (moment magnitude, rupture dimensions and stress drop), achieving good agreement and thereby verifying the modeling of the chain of processes from earthquake inception to ground vibration. We then analyzed the ground vibration results in terms of peak ground acceleration (PGA), peak ground velocity (PGV) and frequency content, with comparison to U.S. Geological Survey's instrumental intensity scales for earthquakes and the U.S. Bureau of Mines' vibration criteria for cosmetic damage to buildings, as well as human-perception vibration limits. Our results confirm the appropriateness of using PGV (rather than PGA) and frequency for the evaluation of potential ground-vibration effects on structures and humans from shallow injection-induced seismic events. For the considered synthetic M w =3 event, our analysis showed that the short duration, high frequency ground motion may not cause any significant damage to surface structures, but would certainly be felt by the local population.« less

Physics-Based Broadband Ground Motion Simulations in Near Fault Conditions: the L'Aquila (Italy) and the Upper Rhine Graben (France-Germany) Case of Studies

NASA Astrophysics Data System (ADS)

Del Gaudio, S.; Lancieri, M.; Hok, S.; Satriano, C.; Chartier, T.; Scotti, O.; Bernard, P.

2016-12-01

Predictions of realistic ground motion for potential future earthquakes are always an interesting task for seismologists and are also the main objective of seismic hazard assessment. While, on one hand, numerical simulations have become more and more accurate and several different techniques have been developed, on the other hand ground motion prediction equations (GMPEs) have become a powerful instrument (due to great improvement of seismic strong motion networks providing a large amount of data). Nevertheless GMPEs do not represent the whole variety of source processes and this can lead to incorrect estimates especially in the near fault conditions because of the lack of records of large earthquakes at short distances. In such cases, physics-based ground motion simulations can be a valid tool to complement prediction equations for scenario studies, provided that both source and propagation are accurately described. We present here a comparison between numerical simulations performed in near fault conditions using two different kinematic source models, which are based on different assumptions and parameterizations: the "k-2 model" and the "fractal model". Wave propagation is taken into account using hybrid Green's function (HGF), which consists in coupling numerical Green's function with an empirical Green's function (EGF) approach. The advantage of this technique is that it does not require a very detailed knowledge of the propagation medium, but requires availability of high quality records of small earthquakes in the target area. The first application we show is on L'Aquila 2009 M 6.3 earthquake, where the main event records provide a benchmark for the synthetic waveforms. Here we can clearly observe which are the limitations of these techniques and investigate which are the physical parameters that are effectively controlling the ground motion level. The second application is a blind test on Upper Rhine Graben (URG) where active faults producing micro seismic activity are very close to sites of interest needing a careful investigation of seismic hazard. Finally we will perform a probabilistic seismic hazard analysis (PSHA) for the URG using numerical simulations to define input ground motion for different scenarios and compare them with a classical probabilistic study based on GMPEs.

Broadband simulations for Mw 7.8 southern san andreas earthquakes: Ground motion sensitivity to rupture speed

USGS Publications Warehouse

Graves, R.W.; Aagaard, Brad T.; Hudnut, K.W.; Star, L.M.; Stewart, J.P.; Jordan, T.H.

2008-01-01

Using the high-performance computing resources of the Southern California Earthquake Center, we simulate broadband (0-10 Hz) ground motions for three Mw 7.8 rupture scenarios of the southern San Andreas fault. The scenarios incorporate a kinematic rupture description with the average rupture speed along the large slip portions of the fault set at 0.96, 0.89, and 0.84 times the local shear wave velocity. Consistent with previous simulations, a southern hypocenter efficiently channels energy into the Los Angeles region along the string of basins south of the San Gabriel Mountains. However, we find the basin ground motion levels are quite sensitive to the prescribed rupture speed, with peak ground velocities at some sites varying by over a factor of two for variations in average rupture speed of about 15%. These results have important implications for estimating seismic hazards in Southern California and emphasize the need for improved understanding of earthquake rupture processes. Copyright 2008 by the American Geophysical Union.

Simulations of Ground Motion in Southern California based upon the Spectral-Element Method

NASA Astrophysics Data System (ADS)

Tromp, J.; Komatitsch, D.; Liu, Q.

2003-12-01

We use the spectral-element method to simulate ground motion generated by recent well-recorded small earthquakes in Southern California. Simulations are performed using a new sedimentary basin model that is constrained by hundreds of petroleum industry well logs and more than twenty thousand kilometers of seismic reflection profiles. The numerical simulations account for 3D variations of seismic wave speeds and density, topography and bathymetry, and attenuation. Simulations for several small recent events demonstrate that the combination of a detailed sedimentary basin model and an accurate numerical technique facilitates the simulation of ground motion at periods of 2 seconds and longer inside the Los Angeles basin and 6 seconds and longer elsewhere. Peak ground displacement, velocity and acceleration maps illustrate that significant amplification occurs in the basin. Centroid-Moment Tensor mechanisms are obtained based upon Pnl and surface waveforms and numerically calculated 3D Frechet derivatives. We use a combination of waveform and waveform-envelope misfit criteria, and facilitate pure double-couple or zero-trace moment-tensor inversions.

Progress report on the Worldwide Earthquake Risk Management (WWERM) Program

USGS Publications Warehouse

Algermissen, S.T.; Hays, Walter W.; Krumpe, Paul R.

1992-01-01

Considerable progress has been made in the Worldwide Earthquake Risk Management (WWERM) Program since its initiation in late 1989 as a cooperative program of the Agency for International Development (AID), Office of U.S. Foreign Disaster Assistance (OFDA), and the U.S. Geological Survey. Probabilistic peak acceleration and peak Modified Mercalli intensity (MMI) maps have been prepared for Chile and for Sulawesi province in Indonesia. Earthquake risk (loss) studies for dwellings in Gorontalo, North Sulawesi, have been completed and risk studies for dwellings in selected areas of central Chile are underway. A special study of the effect of site response on earthquake ground motion estimation in central Chile has also been completed and indicates that site response may modify the ground shaking by as much as plus or minus two units of MMI. A program for the development of national probabilistic ground motion maps for the Philippines is now underway and pilot studies of earthquake ground motion and risk are being planned for Morocco.

Rapid earthquake hazard and loss assessment for Euro-Mediterranean region

NASA Astrophysics Data System (ADS)

Erdik, Mustafa; Sesetyan, Karin; Demircioglu, Mine; Hancilar, Ufuk; Zulfikar, Can; Cakti, Eser; Kamer, Yaver; Yenidogan, Cem; Tuzun, Cuneyt; Cagnan, Zehra; Harmandar, Ebru

2010-10-01

The almost-real time estimation of ground shaking and losses after a major earthquake in the Euro-Mediterranean region was performed in the framework of the Joint Research Activity 3 (JRA-3) component of the EU FP6 Project entitled "Network of Research Infra-structures for European Seismology, NERIES". This project consists of finding the most likely location of the earthquake source by estimating the fault rupture parameters on the basis of rapid inversion of data from on-line regional broadband stations. It also includes an estimation of the spatial distribution of selected site-specific ground motion parameters at engineering bedrock through region-specific ground motion prediction equations (GMPEs) or physical simulation of ground motion. By using the Earthquake Loss Estimation Routine (ELER) software, the multi-level methodology developed for real time estimation of losses is capable of incorporating regional variability and sources of uncertainty stemming from GMPEs, fault finiteness, site modifications, inventory of physical and social elements subjected to earthquake hazard and the associated vulnerability relationships.

Scientific overview and historical context of the 1811-1812 new Madrid earthquake sequence

USGS Publications Warehouse

Hough, S.E.

2004-01-01

aftershock». These values are consistent with other lines of evidence, including scaling relationships. Finally, I show that accounts from the New Madrid sequence reveal evidence for remotely triggered earthquakes well outside the NMSZ. Remotely triggered earthquakes represent a potentially important new wrinkle in historic earthquake research, as their ground motions can sometimes be confused with mainshock ground motions.

Effects of Long-Period Ground Motion on Distant Basins: The 1906 San Francisco Earthquake and Comparison with Japanese Cases

NASA Astrophysics Data System (ADS)

Koketsu, K.; Ikegami, Y.; Kimura, T.; Miyake, H.

2006-12-01

Large earthquakes at shallow depths can excite long-period ground motions affecting large-scale structures in distant sedimentary basins. For example, the 1985 Michoacan, Mexico, earthquake caused 20,000 fatalities in Mexico City at an epicentral distance of 400 km, and the 2003 Tokachi-oki, Japan, earthquake damaged oil tanks in the Yufutsu basin 250 km away (Koketsu et al., 2005). Similar long-range effects were also observed during the 2004 off Kii-peninsula earthquake (Miyake and Koketsu, 2005). In order to examine whether the 1906 San Francisco earthquake and the Los Angeles (LA) basin are in such a case or not, we simulate long- period ground motions in almost whole California caused by the earthquake using the finite element method (FEM) with a voxel mesh (Koketsu et al., 2004). The LA basin is located at a distance of about 600 km from the source region of the 1906 San Francisco earthquake. The 3-D heterogeneous velocity structure model for the ground motion simulation is constructed based on the SCEC Unified Velocity Model for southern California and USGS Bay Area Velocity Model for northern California. The source model of the earthquake is constructed according to Wald et al. (1993). Since we use a mesh with intervals of 500m, the voxel FEM can compute seismic waves with frequencies lower than 0.2 Hz. Although ground motions in the south of the source region are smaller than those in the north because of the rupture directivity effect, we can see fairly developed long- period ground motions in the LA basin in the preliminary result of Kimura et al. (2006). However, we obtained only 8cm/s and 25km/s for PGV and peak velocity response spectrum in the LA basin. We modeled the velocity structure up to a depth of only 20km neglecting the Moho reflections, and we did not include layers with Vs smaller than 1.0 km/s. In this study, we include deeper parts and use a more accurate velocity structure model with low-velocity sediments of Vs smaller than 1.0 km/s.

PSHA in Israel by using the synthetic ground motions from simulated seismicity: the modified SvE procedure

NASA Astrophysics Data System (ADS)

Meirova, T.; Shapira, A.; Eppelbaum, L.

2018-05-01

In this study, we updated and modified the SvE approach of Shapira and van Eck (Nat Hazards 8:201-215, 1993) which may be applied as an alternative to the conventional probabilistic seismic hazard assessment (PSHA) in Israel and other regions of low and moderate seismicity where measurements of strong ground motions are scarce. The new computational code SvE overcomes difficulties associated with the description of the earthquake source model and regional ground-motion scaling. In the modified SvE procedure, generating suites of regional ground motion is based on the extended two-dimensional source model of Motazedian and Atkinson (Bull Seism Soc Amer 95:995-1010, 2005a) and updated regional ground-motion scaling (Meirova and Hofstteter, Bull Earth Eng 15:3417-3436, 2017). The analytical approach of Mavroeidis and Papageorgiou (Bull Seism Soc Amer 93:1099-1131, 2003) is used to simulate the near-fault acceleration with the near-fault effects. The comparison of hazard estimates obtained by using the conventional method implemented in the National Building Code for Design provisions for earthquake resistance of structures and the modified SvE procedure for rock-site conditions indicates a general agreement with some perceptible differences at the periods of 0.2 and 0.5 s. For the periods above 0.5 s, the SvE estimates are systematically greater and can increase by a factor of 1.6. For the soft-soil sites, the SvE hazard estimates at the period of 0.2 s are greater than those based on the CB2008 ground-motion prediction equation (GMPE) by a factor of 1.3-1.6. We suggest that the hazard estimates for the sites with soft-soil conditions calculated by the modified SvE procedure are more reliable than those which can be found by means of the conventional PSHA. This result agrees with the opinion that the use of a standard GMPE applying the NEHRP soil classification based on the V s, 30 parameter may be inappropriate for PSHA at many sites in Israel.

Identification of Natural Frequency of Low Rise Building on Soft Ground Profile using Ambient Vibration Method

NASA Astrophysics Data System (ADS)

Kamarudin, A. F.; Zainal Abidin, M. H.; Mokhatar, S. N.; Daud, M. E.; Ibrahim, A.; Ibrahim, Z.; Noh, M. S. Md

2018-04-01

Natural frequency is the rate at which a body to vibrate or oscillate. Application of ambient vibration (AV) excitation is widely used nowadays as the input motion for building predominant frequency, fo, and ground fundamental frequency, Fo, prediction due to simple, fast, non-destructive, simple handling operation and reliable result. However, it must be emphasized and caution to isolate these frequencies (fo and Fo) from spurious frequencies of site-structure effects especially to low rise building on soft ground deposit. In this study, identification of fo and Fo by using AV measurements were performed on ground and 4-storey primary school reinforced concrete (RC) building at Sekolah Kebangsaan (SK) Sg. Tongkang, Rengit, Johor using 1 Hz of tri-axial seismometer sensor. Overlapping spectra between Fourier Amplitude Spectra (FAS) from and Horizontal to Vertical Spectra Ratio (HVSR) were used to distinguish respective frequencies of building and ground natural frequencies. Three dominant frequencies were identified from the FAS curves at 1.91 Hz, 1.98 Hz and 2.79 Hz in longitudinal (East West-EW), transverse (North South-NS) and vertical (UD) directions. It is expected the building has deformed in translational mode based on the first peak frequency by respective NS and EW components of FAS spectrum. Vertical frequency identified from the horizontal spectrums, might induces to the potential of rocking effect experienced by the school building. Meanwhile, single peak HVSR spectrum at low ground fundamental frequency concentrated at 0.93 Hz indicates to the existence deep contrast of soft deposit. Strong interaction between ground and building at similar frequency (0.93 Hz) observed from the FAS curves on the highest floor has shown the building to behave as a dependent unit against ground response as one rigid mass.

Estimating earthquake magnitudes from reported intensities in the central and eastern United States

USGS Publications Warehouse

Boyd, Oliver; Cramer, Chris H.

2014-01-01

A new macroseismic intensity prediction equation is derived for the central and eastern United States and is used to estimate the magnitudes of the 1811–1812 New Madrid, Missouri, and 1886 Charleston, South Carolina, earthquakes. This work improves upon previous derivations of intensity prediction equations by including additional intensity data, correcting magnitudes in the intensity datasets to moment magnitude, and accounting for the spatial and temporal population distributions. The new relation leads to moment magnitude estimates for the New Madrid earthquakes that are toward the lower range of previous studies. Depending on the intensity dataset to which the new macroseismic intensity prediction equation is applied, mean estimates for the 16 December 1811, 23 January 1812, and 7 February 1812 mainshocks, and 16 December 1811 dawn aftershock range from 6.9 to 7.1, 6.8 to 7.1, 7.3 to 7.6, and 6.3 to 6.5, respectively. One‐sigma uncertainties on any given estimate could be as high as 0.3–0.4 magnitude units. We also estimate a magnitude of 6.9±0.3 for the 1886 Charleston, South Carolina, earthquake. We find a greater range of magnitude estimates when also accounting for multiple macroseismic intensity prediction equations. The inability to accurately and precisely ascertain magnitude from intensities increases the uncertainty of the central United States earthquake hazard by nearly a factor of two. Relative to the 2008 national seismic hazard maps, our range of possible 1811–1812 New Madrid earthquake magnitudes increases the coefficient of variation of seismic hazard estimates for Memphis, Tennessee, by 35%–42% for ground motions expected to be exceeded with a 2% probability in 50 years and by 27%–35% for ground motions expected to be exceeded with a 10% probability in 50 years.

A Little Knowledge of Ground Motion: Explaining 3-D Physics-Based Modeling to Engineers

NASA Astrophysics Data System (ADS)

Porter, K.

2014-12-01

Users of earthquake planning scenarios require the ground-motion map to be credible enough to justify costly planning efforts, but not all ground-motion maps are right for all uses. There are two common ways to create a map of ground motion for a hypothetical earthquake. One approach is to map the median shaking estimated by empirical attenuation relationships. The other uses 3-D physics-based modeling, in which one analyzes a mathematical model of the earth's crust near the fault rupture and calculates the generation and propagation of seismic waves from source to ground surface by first principles. The two approaches produce different-looking maps. The more-familiar median maps smooth out variability and correlation. Using them in a planning scenario can lead to a systematic underestimation of damage and loss, and could leave a community underprepared for realistic shaking. The 3-D maps show variability, including some very high values that can disconcert non-scientists. So when the USGS Science Application for Risk Reduction's (SAFRR) Haywired scenario project selected 3-D maps, it was necessary to explain to scenario users—especially engineers who often use median maps—the differences, advantages, and disadvantages of the two approaches. We used authority, empirical evidence, and theory to support our choice. We prefaced our explanation with SAFRR's policy of using the best available earth science, and cited the credentials of the maps' developers and the reputation of the journal in which they published the maps. We cited recorded examples from past earthquakes of extreme ground motions that are like those in the scenario map. We explained the maps on theoretical grounds as well, explaining well established causes of variability: directivity, basin effects, and source parameters. The largest mapped motions relate to potentially unfamiliar extreme-value theory, so we used analogies to human longevity and the average age of the oldest person in samples of varying sizes to illustrate extreme values to non-scientists. We explained the importance of nonlinearity in the relationship between shaking and loss. This was the second time SAFRR encountered skeptics of 3-D maps among scenario consumers, so a short manuscript was prepared that would serve similar uses in the future.

A hybrid approach to estimate the complex motions of clouds in sky images

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

Peng, Zhenzhou; Yu, Dantong; Huang, Dong

Tracking the motion of clouds is essential to forecasting the weather and to predicting the short-term solar energy generation. Existing techniques mainly fall into two categories: variational optical flow, and block matching. In this article, we summarize recent advances in estimating cloud motion using ground-based sky imagers and quantitatively evaluate state-of-the-art approaches. Then we propose a hybrid tracking framework to incorporate the strength of both block matching and optical flow models. To validate the accuracy of the proposed approach, we introduce a series of synthetic images to simulate the cloud movement and deformation, and thereafter comprehensively compare our hybrid approachmore » with several representative tracking algorithms over both simulated and real images collected from various sites/imagers. The results show that our hybrid approach outperforms state-of-the-art models by reducing at least 30% motion estimation errors compared with the ground-truth motions in most of simulated image sequences. Furthermore, our hybrid model demonstrates its superior efficiency in several real cloud image datasets by lowering at least 15% Mean Absolute Error (MAE) between predicted images and ground-truth images.« less

A hybrid approach to estimate the complex motions of clouds in sky images

DOE PAGES

Peng, Zhenzhou; Yu, Dantong; Huang, Dong; ...

2016-09-14

Tracking the motion of clouds is essential to forecasting the weather and to predicting the short-term solar energy generation. Existing techniques mainly fall into two categories: variational optical flow, and block matching. In this article, we summarize recent advances in estimating cloud motion using ground-based sky imagers and quantitatively evaluate state-of-the-art approaches. Then we propose a hybrid tracking framework to incorporate the strength of both block matching and optical flow models. To validate the accuracy of the proposed approach, we introduce a series of synthetic images to simulate the cloud movement and deformation, and thereafter comprehensively compare our hybrid approachmore » with several representative tracking algorithms over both simulated and real images collected from various sites/imagers. The results show that our hybrid approach outperforms state-of-the-art models by reducing at least 30% motion estimation errors compared with the ground-truth motions in most of simulated image sequences. Furthermore, our hybrid model demonstrates its superior efficiency in several real cloud image datasets by lowering at least 15% Mean Absolute Error (MAE) between predicted images and ground-truth images.« less

Correlation of ground motion and intensity for the 17 January 1994 Northridge, California, earthquake

USGS Publications Warehouse

Boatwright, J.; Thywissen, K.; Seekins, L.C.

2001-01-01

We analyze the correlations between intensity and a set of groundmotion parameters obtained from 66 free-field stations in Los Angeles County that recorded the 1994 Northridge earthquake. We use the tagging intensities from Thywissen and Boatwright (1998) because these intensities are determined independently on census tracts, rather than interpolated from zip codes, as are the modified Mercalli isoseismals from Dewey et al. (1995). The ground-motion parameters we consider are the peak ground acceleration (PGA), the peak ground velocity (PGV), the 5% damped pseudovelocity response spectral (PSV) ordinates at 14 periods from 0.1 to 7.5 sec, and the rms average of these spectral ordinates from 0.3 to 3 sec. Visual comparisons of the distribution of tagging intensity with contours of PGA, PGV, and the average PSV suggest that PGV and the average PSV are better correlated with the intensity than PGA. The correlation coefficients between the intensity and the ground-motion parameters bear this out: r = 0.75 for PGA, 0.85 for PGV, and 0.85 for the average PSV. Correlations between the intensity and the PSV ordinates, as a function of period, are strongest at 1.5 sec (r = 0.83) and weakest at 0.2 sec (r = 0.66). Regressing the intensity on the logarithms of these ground-motion parameters yields relations I ?? mlog?? with 3.0 ??? m ??? 5.2 for the parameters analyzed, where m = 4.4 ?? 0.7 for PGA, 3.4 ?? 0.4 for PGV, and 3.6 ?? 0.5 for the average PSV.

Seismic design and engineering research at the U.S. Geological Survey

USGS Publications Warehouse

1988-01-01

The Engineering Seismology Element of the USGS Earthquake Hazards Reduction Program is responsible for the coordination and operation of the National Strong Motion Network to collect, process, and disseminate earthquake strong-motion data; and, the development of improved methodologies to estimate and predict earthquake ground motion.  Instrumental observations of strong ground shaking induced by damaging earthquakes and the corresponding response of man-made structures provide the basis for estimating the severity of shaking from future earthquakes, for earthquake-resistant design, and for understanding the physics of seismologic failure in the Earth's crust.

Effects of Motion on Skill Acquisition in Future Simulators

DTIC Science & Technology

2006-05-01

performed by Jacobs (1976) concentrated on transfer of training under different motion conditions. Researchers used participants with no prior flying... Autogenic feedback training exercise is superior to promethazine for the treatment of motion sickness. Journal of Clinical Pharmacology, 40, 1154 -1165...motion in simulation was examined. A particular focus was paid to research on the effects of motion cueing on transfer of training from both ground

Seismic Study of Tremor, Deep Long-Period Earthquakes, and Basin Amplification of Ground Motion

NASA Astrophysics Data System (ADS)

Han, Jiangang

In this thesis, we use seismic data and seismological tools to investigate three topics, (1) triggering between slow slip (tremor as proxy) and nearby small earthquakes, (2) mechanisms of deep-long period earthquakes beneath Mount St. Helens, and (3) ground motion amplification in Seattle Basin. In Chapter 1, we investigate 12-year earthquake and tremor catalogs for southwest Japan, and find nearby small intraslab earthquakes are weakly correlated with tremor. In particular, intraslab earthquakes tend to be followed by tremor more often than expected at random, while the excess number of tremor before earthquakes is not as significant. The underlying triggering mechanism of tremor and inferred slow slip by earthquakes is most likely to be the dynamic stress changes (several to several tens of kPa) rather than the much smaller static stress changes. In Chapter 2, we use the catalog DLPs as templates to search for repeating events at Mount St. Helens (MSH). We have detected 277 DLPs, compared to only 22 events previously in the catalog from 2007 to 2016. Three templates from the catalog are single events, while all other templates produced matches, identifying loci of repeated activity. Overall, the detected DLPs show no significant correlation with either the subduction zone tremor and slow slip (ETS) west of MSH, or the shallow seismicity. Temporal analysis shows an elevated rate of DLPs at time of compressional tidal stress, suggesting their possible association with magmatic and/or fluid activity. We observed variable S wave polarization of the DLPs from the most productive DLP source region, indicating their source mechanisms are not identical. In Chapter 3, we use noise correlation to retrieve the empirical green's functions (EGFs) in Seattle Basin. Consistent amplitudes measured from noise EGFs, teleseismic S wave and numerical simulations all suggest the usefulness of the amplitude of EGFs. For surface wave with period of 5-10 sec propagating from west to east, the ground motion is amplified by a factor of up to 3 within the basin. The bias of EGFs from noise heterogeneity and uncertainties of synthetics due to inaccuracy of velocity model are still to be investigated.

Spatial distribution of landslides triggered from the 2007 Niigata Chuetsu–Oki Japan Earthquake

USGS Publications Warehouse

Collins, Brian D.; Kayen, Robert E.; Tanaka, Yasuo

2012-01-01

Understanding the spatial distribution of earthquake-induced landslides from specific earthquakes provides an opportunity to recognize what to expect from future events. The July 16, 2007 Mw 6.6 (MJMA 6.8) Niigata Chuetsu–Oki Japan earthquake triggered hundreds of landslides in the area surrounding the coastal city of Kashiwazaki and provides one such opportunity to evaluate the impacts of an offshore, magnitude 6 + earthquake on a steep coastal region. As part of a larger effort to document all forms of geotechnical damage from this earthquake, we performed landslide inventory mapping throughout the epicentral area and analyzed the resulting data for spatial, seismic-motion, and geologic correlations to describe the pattern of landsliding. Coupled with examination of a third-party, aerial-photo-based landslide inventory, our analyses reveal several areas of high landslide concentration that are not readily explained by either traditional epicentral and fault–plane-distance metrics or by recorded and inferred ground-motions. Whereas average landslide concentrations averaged less than 1 landslide per square kilometer (LS/km2), some areas reached up to 2 LS/km2 in the Nishiyama Hills to the northeast of Kashiwazaki and between 2 and 11 LS/km2 in coastal areas to the north and south of the city. Correlation with seismometer-based and monument overturning back-calculated ground motions suggests that a minimum peak ground acceleration (PGA) of approximately 0.2 g was necessary for landsliding throughout the region, but does not explain the subregional areas of high landslide concentration. However, analysis of topographic slope and the distribution of generally weak, dip-slope, geologic units does sufficiently explain why, on a sub-regional scale, high landslide concentrations occurred where they did. These include: (1) an inland region of steep, dip-slope, anticlinal sedimentary strata with associated fold belt compression and uplift of the anticline and (2) coastal areas with generally weaker, weathered outcrop lithology and steeper slopes resulting from active marine and terrestrial cliff processes. The results offer lessons for understanding the effects of earthquakes on both regional and subregional scales with regard to the spatial distribution of landsliding.

3D Dynamic Rupture Simulations along Dipping Faults, with a focus on the Wasatch Fault Zone, Utah

NASA Astrophysics Data System (ADS)

Withers, K.; Moschetti, M. P.

2017-12-01

We study dynamic rupture and ground motion from dip-slip faults in regions that have high-seismic hazard, such as the Wasatch fault zone, Utah. Previous numerical simulations have modeled deterministic ground motion along segments of this fault in the heavily populated regions near Salt Lake City but were restricted to low frequencies ( 1 Hz). We seek to better understand the rupture process and assess broadband ground motions and variability from the Wasatch Fault Zone by extending deterministic ground motion prediction to higher frequencies (up to 5 Hz). We perform simulations along a dipping normal fault (40 x 20 km along strike and width, respectively) with characteristics derived from geologic observations to generate a suite of ruptures > Mw 6.5. This approach utilizes dynamic simulations (fully physics-based models, where the initial stress drop and friction law are imposed) using a summation by parts (SBP) method. The simulations include rough-fault topography following a self-similar fractal distribution (over length scales from 100 m to the size of the fault) in addition to off-fault plasticity. Energy losses from heat and other mechanisms, modeled as anelastic attenuation, are also included, as well as free-surface topography, which can significantly affect ground motion patterns. We compare the effect of material structure and both rate and state and slip-weakening friction laws have on rupture propagation. The simulations show reduced slip and moment release in the near surface with the inclusion of plasticity, better agreeing with observations of shallow slip deficit. Long-wavelength fault geometry imparts a non-uniform stress distribution along both dip and strike, influencing the preferred rupture direction and hypocenter location, potentially important for seismic hazard estimation.