Regional Design Ground Motion Criteria for the Southern Bering Sea

1990 ◽  
Vol 112 (1) ◽  
pp. 74-82
Author(s):  
Y. K. Vyas ◽  
C. B. Crouse ◽  
B. A. Schell

This paper discusses the development of earthquake design criteria for the Southern Bering Sea—Aleutian Shelf region. The study reported herein was primarily motivated by a high level of seismic activity along the Aleutian Shelf and its potential impact on the design of future offshore and onshore facilities in the region. The criteria were developed for the Strength Level Earthquake (SLE) and Ductility Level Earthquake (DLE). The SLE has an average return period of 200 yr, while the DLE has a return period on the order of 1000’s of years. The criteria were based on the results of probabilistic and deterministic seismic hazard analyses of the region. The probabilistic seismic hazard analyses (SHA) were performed to establish 5 percent damped pseudovelocities (PSV) associated with an average return period of 200 yr for various sites in the region. Although seven seismotectonic provinces were considered, the larger moment magnitude events (Mw > 8.5) occurring in the shallow subduction province contribute most to the 200-yr PSV. A DLE event of Mw 9.2 was selected deterministically to be the maximum earthquake likely to occur in the region based on the tectonics and the historic seismicity. Both SLE and DLE events are associated with major ruptures along the postulated Shumagin-Unalaska seismic gap. Because no earthquake records exist for such severe earthquakes, the design ground motion criteria were partly established using a computer program to simulate ground motions for giant subduction zone earthquakes. Because the SLE and DLE events are similar and because ground motions do not increase significantly beyond Mw = 8.5, the DLE pseudovelocity spectra are about only 10 to 20 percent greater than the SLE spectra. The SLE spectra were compared with the API RP 2A [1] design spectra for this region and significant differences were noted for the region north of the Aleutian Islands. The revised zoning map recommended in this study is believed to provide more realistic standards for the seismic design of future facilities in the region.

1987 ◽  
Vol 77 (4) ◽  
pp. 1110-1126
Author(s):  
Anne S. Kiremidjian ◽  
Shigeru Suzuki

Abstract A stochastic model is presented for estimating probabilities of exceeding site ground motions due to temporally dependent earthquake events. The model reflects the hypothesized dependence of the size of large earthquake events on the time of occurrence of the last major earthquake. An empirical attenuation relationship is used to describe the ground motion at a site originating from a well-defined fault system. The application of the model to the Middle America Trench is discussed. The seismic hazard potential in Mexico City is computed in terms of probabilities of exceeding peak ground acceleration levels. The results indicate that consideration of the seismic gap is important for estimating the seismic hazard at a site. It is also observed that site hazard estimates are greatly dependent on the specific attenuation relationship used. The need for other approaches of ground motion estimation is recognized.


2021 ◽  
pp. 875529302098197
Author(s):  
Jack W Baker ◽  
Sanaz Rezaeian ◽  
Christine A Goulet ◽  
Nicolas Luco ◽  
Ganyu Teng

This manuscript describes a subset of CyberShake numerically simulated ground motions that were selected and vetted for use in engineering response-history analyses. Ground motions were selected that have seismological properties and response spectra representative of conditions in the Los Angeles area, based on disaggregation of seismic hazard. Ground motions were selected from millions of available time series and were reviewed to confirm their suitability for response-history analysis. The processes used to select the time series, the characteristics of the resulting data, and the provided documentation are described in this article. The resulting data and documentation are available electronically.


Author(s):  
Soumya Kanti Maiti ◽  
Gony Yagoda-Biran ◽  
Ronnie Kamai

ABSTRACT Models for estimating earthquake ground motions are a key component in seismic hazard analysis. In data-rich regions, these models are mostly empirical, relying on the ever-increasing ground-motion databases. However, in areas in which strong-motion data are scarce, other approaches for ground-motion estimates are sought, including, but not limited to, the use of simulations to replace empirical data. In Israel, despite a clear seismic hazard posed by the active plate boundary on its eastern border, the instrumental record is sparse and poor, leading to the use of global models for hazard estimation in the building code and all other engineering applications. In this study, we develop a suite of alternative ground-motion models for Israel, based on an empirical database from Israel as well as on four data-calibrated synthetic databases. Two host models are used to constrain model behavior, such that the epistemic uncertainty is captured and characterized. Despite the lack of empirical data at large magnitudes and short distances, constraints based on the host models or on the physical grounds provided by simulations ensure these models are appropriate for engineering applications. The models presented herein are cast in terms of the Fourier amplitude spectra, which is a linear, physical representation of ground motions. The models are suitable for shallow crustal earthquakes; they include an estimate of the median and the aleatory variability, and are applicable in the magnitude range of 3–8 and distance range of 1–300 km.


Author(s):  
Paul Somerville

This paper reviews concepts and trends in seismic hazard characterization that have emerged in the past decade, and identifies trends and concepts that are anticipated during the coming decade. New methods have been developed for characterizing potential earthquake sources that use geological and geodetic data in conjunction with historical seismicity data. Scaling relationships among earthquake source parameters have been developed to provide a more detailed representation of the earthquake source for ground motion prediction. Improved empirical ground motion models have been derived from a strong motion data set that has grown markedly over the past decade. However, these empirical models have a large degree of uncertainty because the magnitude - distance - soil category parameterization of these models often oversimplifies reality. This reflects the fact that other conditions that are known to have an important influence on strong ground motions, such as near- fault rupture directivity effects, crustal waveguide effects, and basin response effects, are not treated as parameters of these simple models. Numerical ground motion models based on seismological theory that include these additional effects have been developed and extensively validated against recorded ground motions, and used to estimate the ground motions of past earthquakes and predict the ground motions of future scenario earthquakes. The probabilistic approach to characterizing the ground motion that a given site will experience in the future is very compatible with current trends in earthquake engineering and the development of building codes. Performance based design requires a more comprehensive representation of ground motions than has conventionally been used. Ground motions estimates are needed at multiple annual probability levels, and may need to be specified not only by response spectra but also by suites of strong motion time histories for input into time-domain non-linear analyses of structures.


1999 ◽  
Vol 89 (4) ◽  
pp. 854-866 ◽  
Author(s):  
John E. Ebel ◽  
Alan L. Kafka

Abstract We have developed a Monte Carlo methodology for the estimation of seismic hazard at a site or across an area. This method uses a multitudinous resampling of an earthquake catalog, perhaps supplemented by parametric models, to construct synthetic earthquake catalogs and then to find earthquake ground motions from which the hazard values are found. Large earthquakes extrapolated from a Gutenberg-Richter recurrence relation and characteristic earthquakes can be included in the analysis. For the ground motion attenuation with distance, the method can use either a set of observed ground motion observations from which estimates are randomly selected, a table of ground motion values as a function of epicentral distance and magnitude, or a parametric ground motion attenuation relation. The method has been tested for sites in New England using an earthquake catalog for the northeastern United States and southeastern Canada, and it yields reasonable ground motions at standard seismic hazard values. This is true both when published ground motion attenuation relations and when a dataset of observed peak acceleration observations are used to compute the ground motion attenuation with distance. The hazard values depend to some extent on the duration of the synthetic catalog and the specific ground motion attenuation used, and the uncertainty in the ground motions increases with decreasing hazard probability. The program gives peak accelerations that are comparable to those of the 1996 U.S. national seismic hazard maps. The method can be adapted to compute seismic hazard for cases where there are temporal or spatial variations in earthquake occurrence rates or source parameters.


2020 ◽  
Vol 110 (5) ◽  
pp. 2380-2397 ◽  
Author(s):  
Gemma Cremen ◽  
Maximilian J. Werner ◽  
Brian Baptie

ABSTRACT An essential component of seismic hazard analysis is the prediction of ground shaking (and its uncertainty), using ground-motion models (GMMs). This article proposes a new method to evaluate (i.e., rank) the suitability of GMMs for modeling ground motions in a given region. The method leverages a statistical tool from sensitivity analysis to quantitatively compare predictions of a GMM with underlying observations. We demonstrate the performance of the proposed method relative to several other popular GMM ranking procedures and highlight its advantages, which include its intuitive scoring system and its ability to account for the hierarchical structure of GMMs. We use the proposed method to evaluate the applicability of several GMMs for modeling ground motions from induced earthquakes due to U.K. shale gas development. The data consist of 195 recordings at hypocentral distances (R) less than 10 km for 29 events with local magnitude (ML) greater than 0 that relate to 2018/2019 hydraulic-fracture operations at the Preston New Road shale gas site in Lancashire and 192 R<10  km recordings for 48 ML>0 events induced—within the same geologic formation—by coal mining near New Ollerton, North Nottinghamshire. We examine: (1) the Akkar, Sandikkaya, and Bommer (2014) models for European seismicity; (2) the Douglas et al. (2013) model for geothermal-induced seismicity; and (3) the Atkinson (2015) model for central and eastern North America induced seismicity. We find the Douglas et al. (2013) model to be the most suitable for almost all of the considered ground-motion intensity measures. We modify this model by recomputing its coefficients in line with the observed data, to further improve its accuracy for future analyses of the seismic hazard of interest. This study both advances the state of the art in GMM evaluation and enhances understanding of the seismic hazard related to U.K. shale gas development.


2019 ◽  
Vol 109 (5) ◽  
pp. 1812-1828 ◽  
Author(s):  
Nenad Bijelić ◽  
Ting Lin ◽  
Gregory G. Deierlein

Abstract Limited data on strong earthquakes and their effect on structures pose challenges of making reliable risk assessments of tall buildings. For instance, although the collapse safety of tall buildings is likely controlled by large‐magnitude earthquakes with long durations and high low‐frequency content, there are few available recorded ground motions to evaluate these issues. The influence of geologic basins on amplifying ground‐motion effects raises additional questions. Absent recorded motions from past large magnitude earthquakes, physics‐based ground‐motion simulations provide a viable alternative. This article examines collapse risk and drift demands of a 20‐story archetype tall building using ground motions at four sites in the Los Angeles (LA) basin. Seismic demands of the building are calculated form nonlinear structural analyses using large datasets (∼500,000 ground motions per site) of unscaled, site‐specific simulated seismograms. Seismic hazard and building performance from direct analysis of Southern California Earthquake Center CyberShake motions are contrasted with values obtained based on conventional approaches that rely on recorded motions coupled with probabilistic seismic hazard assessments. At the LA downtown site, the two approaches yield similar estimates of mean annual frequency of collapse (λc), whereas nonlinear drift demands estimated with direct analysis are slightly larger primarily because of differences in hazard curves. Conversely, at the deep basin site, the CyberShake‐based analysis yields around seven times larger λc than the conventional approach, and both hazard and spectral shapes of the motions drive the differences. Deaggregation of collapse risk is used to identify the relative contributions of causal earthquakes, linking building responses with specific seismograms and contrasting collapse risk with hazard. A strong discriminative power of average spectral acceleration and significant duration for predicting collapse is observed.


2017 ◽  
Vol 33 (3) ◽  
pp. 837-856 ◽  
Author(s):  
Özkan Kale ◽  
Sinan Akkar

We propose a methodology that can be useful to the hazard expert in building ground-motion logic trees to capture the center and range of ground-motion amplitudes. The methodology can be used to identify a logic-tree structure and weighting scheme that prevents the dominancy of a specific ground-motion model. This strategy can be useful for regional probabilistic seismic hazard since logic-trees biased by a specific ground-motion predictive model (GMPE) may cause disparities in the seismic hazard for regions represented by large number of sites with complex seismic features. The methodology first identifies a suit of candidate ground-motion prediction equations that can cover the center, body and range of estimated ground motions. The GMPE set is then used for establishing alternative logic-trees composed of different weighting schemes to identify the one(s) that would not be biased towards a particular GMPE due to its sensitivity to the weights. The proposed methodology utilizes visual and statistical tools to assess the ground motion distributions over large areas that makes it more practical for regional hazard studies.


Author(s):  
Robert E. Chase ◽  
Abbie B. Liel ◽  
Nicolas Luco ◽  
Zach Bullock

AbstractWe evaluate the seismic performance of modern seismically designed wood light-frame (WLF) buildings, considering regional seismic hazard characteristics that influence ground motion duration and frequency content and, thus, seismic risk. Results show that WLF building response correlates strongly with ground motion spectral shape but weakly with duration. Due to the flatter spectral shape of ground motions from subduction events, WLF buildings at sites affected by these earthquakes may experience double the economic losses for a given intensity of shaking, and collapse capacities may be reduced by up to 50%, compared to those at sites affected by crustal earthquakes. These differences could motivate significant increases in design values at sites affected by subduction earthquakes to achieve the uniform risk targets of the American Society of Civil Engineers (ASCE) 7 standard.


2020 ◽  
pp. 875529302097097
Author(s):  
Allison M Shumway ◽  
Mark D Petersen ◽  
Peter M Powers ◽  
Sanaz Rezaeian ◽  
Kenneth S Rukstales ◽  
...  

As part of the update of the 2018 National Seismic Hazard Model (NSHM) for the conterminous United States (CONUS), new ground motion and site effect models for the central and eastern United States were incorporated, as well as basin depths from local seismic velocity models in four western US (WUS) urban areas. These additions allow us, for the first time, to calculate probabilistic seismic hazard curves for an expanded set of spectral periods (0.01 to 10 s) and site classes (VS30 = 150 to 1500 m/s) for the CONUS, as well as account for amplification of long-period ground motions in deep sedimentary basins in the Los Angeles, San Francisco Bay, Seattle, and Salt Lake City areas. Two sets of 2018 NSHM hazard data (hazard curves and uniform-hazard ground motions) are available: (1) 0.05°-latitude-by-0.05°-longitude gridded data for the CONUS and (2) higher resolution 0.01°-latitude-by-0.01°-longitude gridded data for the four WUS basins. Both sets of data contain basin effects in the WUS deep sedimentary basins. Uniform-hazard ground motion data are interpolated for 2, 5, and 10% probability of exceedance in 50 years from the hazard curves. The gridded data for the hazard curves and uniform-hazard ground motions, for all periods and site classes, are available for download at the U.S. Geological Survey ScienceBase Catalog ( https://doi.org/10.5066/P9RQMREV ). The design ground motions derived from the hazard curves have been accepted by the Building Seismic Safety Council for adoption in the 2020 National Earthquake Hazard Reduction Program Recommended Seismic Provisions.


Sign in / Sign up

Export Citation Format

Share Document