Download or read book Variability in Characteristics of Ground Motions Across North America written by Alireza Babaie Mahani and published by . This book was released on 2013 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, ground motions from earthquakes in North America with moment magnitude (M) 3.0 to 6.0 were investigated to reveal regional differences in ground motion amplitudes. First, we examined several attenuation forms to evaluate their ability to describe the decay of response spectral amplitudes in different regions across North America. Linear, bi-linear and tri-linear regression forms with different combinations of geometric spreading coefficients were tested to assess their ability to describe spectral amplitude decay from 0.33 to 10 Hz in the distance range from 10 to 400 km. We found that the linear model has steeper slope in the west (~1.3) than in the east (~1), and may not extend well over large distances. The bi-linear form offers a good compromise between simplicity and the ability to model amplitude decay appropriately at both near and regional distances. Although tri-linear models are a better fit to the data in some regions (Eastern North America), they may have no practical advantage over simpler models. In the second step, a simple and robust approach to estimate moment magnitude (M) for events of M

Download or read book Impact of Ground Motion Characterization on Conservatism and Variability in Seismic Risk Estimates written by and published by . This book was released on 1996 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study evaluates the impact, on estimates of seismic risk and its uncertainty, of alternative methods in treatment and characterization of earthquake ground motions. The objective of this study is to delineate specific procedures and characterizations that may lead to less biased and more precise seismic risk results. This report focuses on sources of conservatism and variability in risk that may be introduced through the analytical processes and ground-motion descriptions which are commonly implemented at the interface of seismic hazard and fragility assessments. In particular, implication of the common practice of using a single, composite spectral shape to characterize motions of different magnitudes is investigated. Also, the impact of parameterization of ground motion on fragility and hazard assessments is shown. Examination of these results demonstrates the following. (1) There exists significant conservatism in the review spectra (usually, spectra characteristic of western U.S. earthquakes) that have been used in conducting past seismic risk assessments and seismic margin assessments for eastern U.S. nuclear power plants. (2) There is a strong dependence of seismic fragility on earthquake magnitude when PGA is used as the ground-motion characterization. When, however, magnitude-dependent spectra are anchored to a common measure of elastic spectral acceleration averaged over the appropriate frequency range, seismic fragility shows no important nor consistent dependence on either magnitude or strong-motion duration. Use of inelastic spectral acceleration (at the proper frequency) as the ground spectrum anchor demonstrates a very similar result. This study concludes that a single, composite-magnitude spectrum can generally be used to characterize ground motion for fragility assessment without introducing significant bias or uncertainty in seismic risk estimates.

Download or read book Geostatistical and Network Analysis of Non stationary Spatial Variation in Ground Motion Amplitudes written by Yilin Chen and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: When an earthquake causes shaking in a region, the amplitude of shaking varies spatially. Ground motion models have been developed to predict the median and standard deviation of ground motion intensity measures. However, the remaining variation in ground motion prediction ``residuals'' is significant, and shows spatial correlations at scales of tens of kilometers in separation distance. These correlations are important when assessing the risk to spatially distributed infrastructure or portfolios of properties. State of the art today is to assume that these spatial correlations depend mainly on separation distance (stationarity assumption). This dissertation aims to advance spatial correlation models of ground motions, by conducting a comprehensive correlation study on various data sets, evaluating key assumptions of current models, and proposing a novel framework for modeling spatial correlations. First, this dissertation proposes a method of site-specific correlation estimation and techniques for quantifying non-stationary spatial variations. Applying these methods to various data sets, factors related to non-stationary spatial correlations are investigated. Using physics-based ground motion simulations, it studies the dependency of non-stationary spatial correlations on source effects, path effects, and relative location to rupture. Using data from recent well-recorded earthquakes in New Zealand, it analyzes site-specific and region-specific correlations in ground motion amplitude for Wellington and Christchurch, and observed strong non-stationarity in spatial correlations. Results suggest that heterogeneous geologic conditions appear to be associated with the non-stationary spatial correlation. Second, this dissertation formulates a framework for detecting and modeling non-stationary correlations. By utilizing network analysis techniques, it proposes a community detection algorithm to find regions in spatial data with higher correlations. Applying this algorithm to physics-based ground motion simulations, it detects communities of earthquake stations with high correlation to uncover underlying reasons for non-stationarity in spatial correlations. Factors associated with the communities of high correlation are identified. Results suggest that communities of high correlation in ground shaking tend to be associated with common geological conditions and relative location along the rupture strike direction. In addition, it applies the algorithm to a mixed-source data set from the simulations, and compares correlation characteristics of simulations and instrumental data. Results suggest that the mixed-source data tend to average out the non-stationary influence of source and path effects from a single rupture. Finally, this dissertation presents a framework for quantifying uncertainty in the estimation of correlations, and true variability in correlations from earthquake to earthquake. A procedure for evaluating estimation uncertainty is proposed and used to evaluate several methods that have been used in past studies to estimate correlations. The proposed procedure is also used to distinguish between estimation uncertainty and the true variability in model parameters that exist in a given data set. Results suggest that a Weighted Least Squares fitting method is most effective for correlation model estimation. Fitted correlation model parameters are shown to have substantial estimation uncertainty even for well-recorded earthquakes, and underlying true variability is relatively stable among well-recorded and poorly recorded earthquakes.

Download or read book Spatial Variation of Seismic Ground Motions written by Aspasia Zerva and published by CRC Press. This book was released on 2016-04-19 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: The spatial variation of seismic ground motions denotes the differences in the seismic time histories at various locations on the ground surface. This text focuses on the spatial variability of the motions that is caused by the propagation of the waveforms from the earthquake source through the earth strata to the ground surface, and it brings toge

Download or read book Earthquake Data in Engineering Seismology written by Sinan Akkar and published by Springer Science & Business Media. This book was released on 2011-01-03 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses current activities in strong-motion networks around the globe, covering issues related to designing, maintaining and disseminating information from these arrays. The book is divided into three principal sections. The first section includes recent developments in regional and global ground-motion predictive models. It presents discussions on the similarities and differences of ground motion estimations from these models and their application to design spectra as well as other novel procedures for predicting engineering parameters in seismic regions with sparse data. The second section introduces topics about the particular methodologies being implemented in the recently established global and regional strong-motion databanks in Europe to maintain and disseminate the archived accelerometric data. The final section describes major strong-motion arrays around the world and their historical developments. The last three chapters of this section introduce projects carried out within the context of arrays deployed for seismic risk studies in metropolitan areas. Audience: This timely book will be of particular interest for researchers who use accelerometric data extensively to conduct studies in earthquake engineering and engineering seismology.

Download or read book Recent Advances in North American Paleoseismology and Neotectonics East of the Rockies written by Randel Tom Cox and published by Geological Society of America. This book was released on 2012 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This volume focuses on the continental intraplate region of the United States and provides an update and overview of documented Quaternary faulting and paleoseismic liquefaction east of the Rocky Mountains, and of the application of these results to seismic hazard and risk assessments. Contributions include papers that describe zones of newly recognized Quaternary deformation such as the East Tennessee Seismic Zone, as well as reinterpretations of well-known areas such as the New Madrid Seismic Zone. The chapters make important contributions to the recognition of earthquake sources active during the Quaternary and assess the seismic hazards posed by these sources. This volume should interest a wide range of readers from geology, seismology, hazard assessment, and emergency management"--Provided by publisher.

Download or read book U S Geological Survey Professional Paper written by and published by . This book was released on 1984 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Publications of the U S Geological Survey written by Geological Survey (U.S.) and published by . This book was released on 1992 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ground Motion and Variability from 3 D Deterministic Broadband Simulations written by Kyle Withers and published by . This book was released on 2016 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The accuracy of earthquake source descriptions is a major limitation in high-frequency ($>1$ Hz) deterministic ground motion prediction, which is critical for performance-based design by building engineers. With the recent addition of realistic fault topography in 3D simulations of earthquake source models, ground motion can be deterministically calculated more realistically up to higher frequencies. We first introduce a technique to model frequency-dependent attenuation and compare its impact on strong ground motions recorded for the 2008 Chino Hills earthquake. Then, we model dynamic rupture propagation for both a generic strike-slip event and blind thrust scenario earthquakes matching the fault geometry of the 1994 Mw 6.7 Northridge earthquake along rough faults up to 8 Hz. We incorporate frequency-dependent attenuation via a power law above a reference frequency in the form $Q_0f^n$ ,with high accuracy down to Q values of 15, and include nonlinear effects via Drucker-Prager plasticity. We model the region surrounding the fault with and without small-scale medium complexity in both a 1D layered model characteristic of southern California rock and a 3D medium extracted from the SCEC CVMSi.426 including a near-surface geotechnical layer. We find that the spectral acceleration from our models are within 1-2 interevent standard deviations from recent ground motion prediction equations (GMPEs) and compare well with that of recordings from strong ground motion stations at both short and long periods. At periods shorter than 1 second, Q(f) is needed to match the decay of spectral acceleration seen in the GMPEs as a function of distance from the fault. We find that the similarity between the intraevent variability of our simulations and observations increases when small-scale heterogeneity and plasticity are included, extremely important as uncertainty in ground motion estimates dominates the overall uncertainty in seismic risk. In addition to GMPEs, we compare with simple proxy metrics to evaluate the performance of our deterministic models and to determine the importance of different complexities within our model. We find that 3D heterogeneity, at both the long and short scale-lengths, is necessary to agree with data, and should be included in future simulations to best model the ground motion from earthquakes.

Download or read book Probabilistic Estimates of the Seismic Ground motion Hazard in Western Saudi Arabia written by P. C. Thenhaus and published by . This book was released on 1989 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings from the Symposium on Seismic Hazards Ground Motions Soil Liquefaction and Engineering Practice in Eastern North America written by Klaus Jacob and published by . This book was released on 1987 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Spatial Variation of Ground Motions on Large Multiple Supported Structures written by Hong Hao and published by . This book was released on 1989 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Publications of the Geological Survey written by Geological Survey (U.S.) and published by . This book was released on 1989 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ground motion Variability Resulting from the January 17 1994 M written by Lawrence Hutchings and published by . This book was released on 1994 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Investigation Into Earthquake Ground Motion Characteristics in Japan with Emphasis on the 2011 M9 0 Tohoku Earthquake written by Hadi Ghofrani and published by . This book was released on 2012 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this integrated study, ground-motion characteristics of one of the most devastating earthquakes in history, the 11th March 2011 Tohoku-oki earthquake (moment magnitude (M) 9.0), are investigated. The investigation centers on developing empirical and simulated-based ground-motion prediction models for this earthquake. These models allow prediction of expected ground motions from large interface (mega-thrust) earthquakes and estimation of their variability due to variability in input parameters, specifically source characteristics (e.g. slip distributions), propagation path, and site effects. This research work can be divided into two main parts. In the first part, the influence of regional geologic structure, in particular the attenuation effects of seismic wave amplitudes with distance while traveling through a volcanic arc region (forearc versus backarc attenuation), is empirically evaluated using regression analysis of Fourier amplitude spectra (FAS) of well-recorded Japanese events. It is concluded that the separation of forearc and backarc travel paths results in a significant reduction in the standard deviation (sigma) of ground motion predictions (by as much as 0.05 log10 units). The distinction between forearc and backarc attenuation has important implications for hazard analysis in subduction regions. In the second part, the ground-motion characteristics of the 2011 Tohoku earthquake are investigated. First, site response in Japan is thoroughly characterized using thousands of surface and borehole recordings. Site amplification effects are found to be very strong at most sites, often exceeding a factor of five. It is concluded that the large observed groundmotion amplitudes at high frequencies during the Tohoku event are mainly due to the prevalence of shallow-soil conditions in Japan that amplified higher frequencies. A stochastic finite-fault model was used to simulate average response spectra of the Tohoku earthquake, for comparison with observed ground motions. The simulation results show that use of a source model comprised of several rupture asperities produces ground motions that are in good agreement with the observations at both high- and low-frequency ranges, and also provides an accurate description of the temporal characteristics of observed ground motions. The calibrated model for the 2011 Tohoku earthquake can be utilized to predict ground motions for future large events in other regions, such as the Cascadia region of North America, by suitable modifications of the regional attenuation and site parameters.

Download or read book Seismological Research Letters written by and published by . This book was released on 2006 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Open file Report written by and published by . This book was released on 1989 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: