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Author: Yilin Chen
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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.
Author: Yilin Chen
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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.
Author: Richard Webster
Publisher: John Wiley & Sons
ISBN: 9780470517260
Category : Mathematics
Languages : en
Pages : 330
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Book Description
Geostatistics is essential for environmental scientists. Weather and climate vary from place to place, soil varies at every scale at which it is examined, and even man-made attributes – such as the distribution of pollution – vary. The techniques used in geostatistics are ideally suited to the needs of environmental scientists, who use them to make the best of sparse data for prediction, and top plan future surveys when resources are limited. Geostatistical technology has advanced much in the last few years and many of these developments are being incorporated into the practitioner’s repertoire. This second edition describes these techniques for environmental scientists. Topics such as stochastic simulation, sampling, data screening, spatial covariances, the variogram and its modeling, and spatial prediction by kriging are described in rich detail. At each stage the underlying theory is fully explained, and the rationale behind the choices given, allowing the reader to appreciate the assumptions and constraints involved.
Author: Yoshifumi Yamamoto
Publisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 329
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Book Description
For performance-based design, nonlinear dynamic structural analysis for various types of input ground motions is required. Stochastic (simulated) ground motions are sometimes useful as input motions, because unlike recorded motions they are not limited in number and because their properties can be varied systematically to study the impact of ground motion properties on structural response. This dissertation describes an approach by which the wavelet packet transform can be used to characterize complex time-varying earthquake ground motions, and it illustrates the potential benefits of such an approach in a variety of earthquake engineering applications. The proposed model is based on Thr´ainsson and Kiremidjian (2002), which use Fourier amplitudes and phase differences to simulate ground motions and attenuation models to their model parameters. We extend their model using wavelet packet transform since it can control the time and frequency characteristic of time series. The time- and frequency-varying properties of real ground motions can be captured using wavelet packets, so a model is developed that requires only 13 parameters to describe a given ground motion. These 13 parameters are then related to seismological variables such as earthquake magnitude, distance, and site condition, through regression analysis that captures trends in mean values, standard deviations and correlations of these parameters observed in a large database of recorded strong ground motions. The resulting regression equations then form a model that can be used to predict ground motions for a future earthquake scenario; this model is analogous to widely used empirical ground motion prediction models (formerly called "attenuation models") except that this model predicts entire time series rather than only response spectra. The ground motions produced using this predictive model are explored in detail, and are shown to have elastic response spectra, inelastic response spectra, durations, mean periods, etc., that are consistent in both mean and variability to existing published predictive models for those properties. That consistency allows the proposed model to be used in place of existing models for probabilistic seismic hazard analysis (PSHA) calculations. This new way to calculate PSHA is termed "simulation-based probabilistic seismic hazard analysis" and it allows a deeper understanding of ground motion hazard and hazard deaggregation than is possible with traditional PSHA because it produces a suite of potential ground motion time histories rather than simply a distribution of response spectra. The potential benefits of this approach are demonstrated and explored in detail. Taking this analysis even further, this suite of time histories can be used as input for nonlinear dynamic analysis of structures, to perform a risk analysis (i.e., "probabilistic seismic demand analysis") that allows computation of the probability of the structure exceeding some level of response in a future earthquake. These risk calculations are often performed today using small sets of scaled recorded ground motions, but that approach requires a variety of assumptions regarding important properties of ground motions, the impacts of ground motion scaling, etc. The approach proposed here facilitates examination of those assumptions, and provides a variety of other relevant information not obtainable by that traditional approach.
Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 1006
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Book Description
Author: Nozomu Yoshida
Publisher: Springer
ISBN: 940179460X
Category : Science
Languages : en
Pages : 370
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Book Description
This book presents state-of-the-art information on seismic ground response analysis, and is not only very valuable and useful for practitioners but also for researchers. The topics covered are related to the stages of analysis: 1. Input parameter selection, by reviewing the in-situ and laboratory tests used to determine dynamic soil properties as well as the methods to compile and model the dynamic soil properties from literature;2. Input ground motion; 3. Theoretical background on the equations of motion and methods for solving them; 4. The mechanism of damping and how this is modeled in the equations of motions; 5. Detailed analysis and discussion of results of selected case studies which provide valuable information on the problem of seismic ground response analysis from both a theoretical and practical point of view.
Author: Michael Beer
Publisher: Springer
ISBN: 9783642353437
Category : Technology & Engineering
Languages : en
Pages : 3953
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Book Description
The Encyclopedia of Earthquake Engineering is designed to be the authoritative and comprehensive reference covering all major aspects of the science of earthquake engineering, specifically focusing on the interaction between earthquakes and infrastructure. The encyclopedia comprises approximately 300 contributions. Since earthquake engineering deals with the interaction between earthquake disturbances and the built infrastructure, the emphasis is on basic design processes important to both non-specialists and engineers so that readers become suitably well informed without needing to deal with the details of specialist understanding. The encyclopedia’s content provides technically-inclined and informed readers about the ways in which earthquakes can affect our infrastructure and how engineers would go about designing against, mitigating and remediating these effects. The coverage ranges from buildings, foundations, underground construction, lifelines and bridges, roads, embankments and slopes. The encyclopedia also aims to provide cross-disciplinary and cross-domain information to domain-experts. This is the first single reference encyclopedia of this breadth and scope that brings together the science, engineering and technological aspects of earthquakes and structures.
Author: B.S. Daya Sagar
Publisher: Springer
ISBN: 3319789996
Category : Science
Languages : en
Pages : 911
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Book Description
This Open Access handbook published at the IAMG's 50th anniversary, presents a compilation of invited path-breaking research contributions by award-winning geoscientists who have been instrumental in shaping the IAMG. It contains 45 chapters that are categorized broadly into five parts (i) theory, (ii) general applications, (iii) exploration and resource estimation, (iv) reviews, and (v) reminiscences covering related topics like mathematical geosciences, mathematical morphology, geostatistics, fractals and multifractals, spatial statistics, multipoint geostatistics, compositional data analysis, informatics, geocomputation, numerical methods, and chaos theory in the geosciences.
Author:
Publisher: Academic Press
ISBN: 0128216840
Category : Science
Languages : en
Pages : 318
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Book Description
Advances in Geophysics, Volume 61 - Machine Learning and Artificial Intelligence in Geosciences, the latest release in this highly-respected publication in the field of geophysics, contains new chapters on a variety of topics, including a historical review on the development of machine learning, machine learning to investigate fault rupture on various scales, a review on machine learning techniques to describe fractured media, signal augmentation to improve the generalization of deep neural networks, deep generator priors for Bayesian seismic inversion, as well as a review on homogenization for seismology, and more. - Provides high-level reviews of the latest innovations in geophysics - Written by recognized experts in the field - Presents an essential publication for researchers in all fields of geophysics
Author: Aspasia Zerva
Publisher: CRC Press
ISBN: 1420009915
Category : Science
Languages : en
Pages : 488
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Book Description
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
Author: Jack Baker
Publisher: Cambridge University Press
ISBN: 9781108425056
Category : Technology & Engineering
Languages : en
Pages : 600
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Book Description
Seismic hazard and risk analyses underpin the loadings prescribed by engineering design codes, the decisions by asset owners to retrofit structures, the pricing of insurance policies, and many other activities. This is a comprehensive overview of the principles and procedures behind seismic hazard and risk analysis. It enables readers to understand best practises and future research directions. Early chapters cover the essential elements and concepts of seismic hazard and risk analysis, while later chapters shift focus to more advanced topics. Each chapter includes worked examples and problem sets for which full solutions are provided online. Appendices provide relevant background in probability and statistics. Computer codes are also available online to help replicate specific calculations and demonstrate the implementation of various methods. This is a valuable reference for upper level students and practitioners in civil engineering, and earth scientists interested in engineering seismology.
