A stochastic model for site ground motions from temporally dependent earthquakes

1987 ◽  
Vol 77 (4) ◽  
pp. 1110-1126
Author(s):  
Anne S. Kiremidjian ◽  
Shigeru Suzuki
Keyword(s):  
Seismic Hazard ◽  
Stochastic Model ◽  
Ground Motion ◽  
Ground Motions ◽  
Large Earthquake ◽  
Fault System ◽  
Seismic Gap ◽  
Attenuation Relationship ◽  
Ground Acceleration ◽  
A Site

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.

Towards physics-based PSHA using CyberShake in the South Iceland Seismic Zone

2021 ◽  
Author(s):  
Otilio Rojas ◽  
Juan Esteban Rodriguez ◽  
Josep de la Puente ◽  
Scott Callaghan ◽  
Claudia Abril ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Fault System ◽  
Seismic Zone ◽  
The South ◽  
Modeling Tools ◽  
Slip Rates ◽  
South Iceland Seismic Zone ◽  
Earthquake Simulations

<p>Traditional Probabilistic Seismic Hazard Analysis (PSHA) estimates the level of earthquake ground shaking that is expected to be exceeded with a given recurrence time on the basis of  historical earthquake catalogues and empirical and time-independent Ground Motion Prediction Equations (GMPEs). The smooth nature of GMPEs usually disregards some well known drivers of ground motion characteristics associated with fault rupture processes, in particular in the near-fault region, complex source-site propagation of seismic waves, and sedimentary basin response. Modern physics-based earthquake simulations can consider all these effects, but require a large set of input parameters for which constraints may often be scarce. However, with the aid of high-performance computing (HPC) infrastructures  the parameter space may be sampled in an efficient and scalable manner allowing for a large suite of site-specific ground motion simulations that approach the center, body and range of expected ground motions. </p><p>CyberShake is a HPC platform designed to undertake physics-based PSHA from a large suite of earthquake simulations. These simulations are based on seismic reciprocity, rendering PSHA computationally tractable for hundreds of thousands potential earthquakes. For each site of interest, multiple kinematic rupture scenarios, derived by varying slip distributions and hypocenter location across the pre-defined fault system, are generated from an input Earthquake Forecast Model (EFM). Each event is simulated to determine ground motion intensities, which are synthesized into hazard results. CyberShake has been developed by the Southern California Earthquake Center, and used so far to assess seismic hazard in California. This work focuses on the CyberShake migration to the seismic region of South Iceland (63.5°- 64.5°N, 20°-22°W) where the largely sinistral East-West transform motion across the tectonic margin is taken up by a complex array of near-vertical and parallel North-South oriented dextral transform faults in the South Iceland Seismic Zone (SISZ) and the Reykjanes Peninsula Oblique Rift (RPOR). Here, we describe the main steps of migrating CyberShake to the SISZ and RPOR, starting by setting up a relational input database describing potential causative faults and rupture characteristics, and key sites of interest. To simulate our EFM, we use the open source code SHERIFS, a logic-tree method that converts the slip rates of complex fault systems to the corresponding annual seismicity rate. The fault slip rates are taken from a new 3D physics-based fault model for the SISZ-RPOR transform fault system. To validate model and simulation parameters, two validation steps using key CyberShake modeling tools have been carried out. First, we perform simulations of historical earthquakes and compare the synthetics with recorded ground motions and results from other forward simulations. Second, we adjust the rupture kinematics to make slip distributions more representative of SISZ-type earthquakes by comparing with static slip distributions of past significant earthquakes. Finally, we run CyberShake and compare key parameters of the synthetic ground motions with new GMPEs available for the study region. The successful migration and use of CyberShake in South Iceland is the first step of a full-scale physics-based PSHA in the region, and showcases the implementation of CyberShake in new regions.</p>

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
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Return Period ◽  
Bering Sea ◽  
Ground Motions ◽  
Seismic Gap ◽  
Average Return ◽  
Shelf Region ◽  
High Level ◽  
Maximum Earthquake

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.

Toward Physics-Based Nonergodic PSHA: A Prototype Fully Deterministic Seismic Hazard Model for Southern California

2021 ◽  
Author(s):  
Kevin R. Milner ◽  
Bruce E. Shaw ◽  
Christine A. Goulet ◽  
Keith B. Richards-Dinger ◽  
Scott Callaghan ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Dynamic Models ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Stress Transfer ◽  
Physical Models ◽  
Fault System ◽  
Intrinsic Variability ◽  
Time Histories

ABSTRACT We present a nonergodic framework for probabilistic seismic-hazard analysis (PSHA) that is constructed entirely of deterministic, physical models. The use of deterministic ground-motion simulations in PSHA calculations is not new (e.g., CyberShake), but prior studies relied on kinematic rupture generators to extend empirical earthquake rupture forecasts. Fully dynamic models, which simulate rupture nucleation and propagation of static and dynamic stresses, are still computationally intractable for the large simulation domains and many seismic cycles required to perform PSHA. Instead, we employ the Rate-State earthquake simulator (RSQSim) to efficiently simulate hundreds of thousands of years of M≥6.5 earthquake sequences on the California fault system. RSQSim produces full slip-time histories for each rupture, which, unlike kinematic models, emerge from frictional properties, fault geometry, and stress transfer; all intrinsic variability is deterministic. We use these slip-time histories directly as input to a 3D wave-propagation code within the CyberShake platform to obtain simulated Fmax=0.5  Hz ground motions. The resulting 3 s spectral acceleration ground motions closely match empirical ground-motion model (GMM) estimates of median and variability of shaking. When computed over a range of sources and sites, the variability is similar to that of ergodic GMMs. Variability is reduced for individual pairs of sources and sites that repeatedly sample a single path, which is expected for a nonergodic model. This results in increased exceedance probabilities for certain characteristic ground motions for a source–site pair, while decreasing probabilities at the extreme tails of the ergodic GMM predictions. We present these comparisons and preliminary fully deterministic physics-based RSQSim–CyberShake hazard curves, as well as a new technique for estimating within- and between-event variability through simulation.

What is a reference site?

1996 ◽  
Vol 86 (6) ◽  
pp. 1733-1748 ◽  
Author(s):  
Jamison H. Steidl ◽  
Alexei G. Tumarkin ◽  
Ralph J. Archuleta
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Reference Site ◽  
Site Response ◽  
Ground Motions ◽  
Destructive Interference ◽  
Surface Rock ◽  
Reference Motion ◽  
Rock Site ◽  
A Site

Abstract Many methods for estimating site response compare ground motions at sites of interest to a nearby rock site that is considered a “reference” motion. The critical assumption in these methods is that the surface-rock-site record (reference) is equivalent to the input motion at the base of the soil layers. Data collected in this study show that surface-rock sites can have a site response of their own, which could lead to an underestimation of the seismic hazard when these sites are used as reference sites. Data were collected from local and regional earthquakes on digital recorders, both at the surface and in boreholes, at two rock sites and one basin site in the San Jacinto mountains, southern California. The two rock sites, Keenwild and Piñon Flat, are located on granitic bedrock of the southern California peninsular ranges batholith. The basin site, Garner Valley, is an ancestral lake bed with watersaturated sediments, on top of a section of decomposed granite, which overlies the competent bedrock. Ground motion is recorded simultaneously at the surface and in the bedrock at all three sites. When the surface-rock sites are used as the reference site, i.e., the surface-rock motion is used as the input to the basin, the computed amplification underestimates the actual amplification at the basin site for frequencies above 2 to 5 Hz. This underestimation, by a factor of 2 to 4 depending on frequency and site, results from the rock sites having a site response of their own above the 2-to 5-Hz frequencies. The near-surface weathering and cracking of the bedrock affects the recorded ground motions at frequencies of engineering interest, even at sites that appear to be located on competent crystalline rock. The bedrock borehole ground motion can be used as the reference motion, but the effect of the downgoing wave field and the resulting destructive interference must be considered. This destructive interference may produce pseudo-resonances in the spectral amplification estimates. If one is careful, the bedrock borehole ground motion can be considered a good reference site for seismic hazard analysis even at distances as large as 20 km from the soil site.

scholarly journals Probabilistic Seismic Hazards Analysis of Ambikapur-Chhattisgarh (India)

2021 ◽  
Vol 9 (2) ◽  
pp. 83-91
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Peak Ground Acceleration ◽  
Hazard Analysis ◽  
Seismic Hazard Analysis ◽  
Probabilistic Seismic Hazard ◽  
Attenuation Relationship ◽  
Ground Acceleration ◽  
Probability Of Exceedance ◽  
Maximum Peak

The present study reveals the seismic hazard analysis of district headquarter Ambikapur, in the state of Chhattisgarh. Usually, seismic hazard study attempts to analyze two different kinds of anticipated ground motions, “the Deterministic Seismic Hazard Analysis (DSHA)” and “the Probabilistic Seismic Hazard Analysis (PSHA)”. The maximum Peak Ground Acceleration (PGA) has been estimated by using Iyengar and Raghu Kanth (2004) attenuation relationship. The regional recurrences relation is obtained by using available historical data and 33 numbers of seismic sources (liner faults) that are likely to cause ground motion, around the study area. The probabilistic seismic hazard analysis has been applied over Ambikapur, to assess the probability of exceedance for various PGA(g)values the seismic hazard curve has been developed by using Raghu Kanth and Iyengar (2007) attenuation relationship. Theprobability of exceedance for PGA(g) values as 0.01g,0.05g,0.10g,0.15g for their corresponding return periods have also been assessed. The liner seismic source having length 46kM, produced maximum peak ground motion as 0.15259g for recurrence period of 100 years. For Ambikapur district headquarter the probability of exceedance for 0.1g with a return period of 8788 years is estimated as 63.22%. Maximum Peak Ground Acceleration value and % probability of exceedance reflects that the seismicity of Ambikapur district headquarter is found to have exceeded from 0.1g as recommended by IS:1893 (Part 1): 2016 (Sixth Revision) for Chhattisgarh. Hence, it is recommended from present study that, Ambikapur should be included in zone III instead of zone II.

A subset of CyberShake ground-motion time series for response-history analysis

2021 ◽  
pp. 875529302098197
Author(s):  
Jack W Baker ◽  
Sanaz Rezaeian ◽  
Christine A Goulet ◽  
Nicolas Luco ◽  
Ganyu Teng
Keyword(s):  
Time Series ◽  
Los Angeles ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Motion Time ◽  
History Analysis ◽  
Response History Analysis ◽  
Simulated Ground Motions

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.

Site effects of the Denis-Perron dam (SM-3): A case study in Eastern North America

2021 ◽  
pp. 875529302110194
Author(s):  
Daniel Verret ◽  
Denis LeBœuf ◽  
Éric Péloquin
Keyword(s):  
North America ◽  
Ground Motion ◽  
Site Effects ◽  
Transfer Functions ◽  
Ground Motions ◽  
Published Data ◽  
Eastern North America ◽  
Ground Acceleration ◽  
Large Dams ◽  
Moderate Seismicity

Eastern North America (ENA) is part of a region with low-to-moderate seismicity; nonetheless, some significant seismic events have occurred in the last few decades. Recent events have reemphasized the need to review ENA seismicity and ground motion models, along with continually reevaluating and updating procedures related to the seismic safety assessment of hydroelectric infrastructures, particularly large dams in Québec. Furthermore, recent researchers have shown that site-specific characteristics, topography, and valley shapes may significantly aggravate the severity of ground motions. To the best of our knowledge, very few instrumental data from actual earthquakes have been published for examining the site effects of hydroelectric dam structures located in eastern Canada. This article presents an analysis of three small earthquakes that occurred in 1999 and 2002 at the Denis-Perron (SM-3) dam. This dam, the highest in Québec, is a rockfill embankment structure with a height of 171 m and a length of 378 m; it is located in a narrow valley. The ground motion datasets of these earthquakes include the bedrock and dam crest three-component accelerometer recordings. Ground motions are analyzed both in the time and frequency domains. The spectral ratios and transfer functions obtained from these small earthquakes provide new insights into the directionality of resonant frequencies, vibration modes, and site effects for the Denis-Perron dam. The crest amplifications observed for this dam are also compared with previously published data for large dams. New statistical relationships are proposed to establish dam crest amplification on the basis of the peak ground acceleration (PGA) at the foundation.

scholarly journals Seismic Hazard Assessment for the Tianshui Urban Area, Gansu Province, China

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Zhenming Wang ◽  
David T. Butler ◽  
Edward W. Woolery ◽  
Lanmin Wang
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Design ◽  
Hazard Analysis ◽  
Seismic Hazard Assessment ◽  
Gansu Province ◽  
Mitigation Measures ◽  
Peak Ground Velocity ◽  
Ground Acceleration ◽  
Acceleration Time Histories

A scenario seismic hazard analysis was performed for the city of Tianshui. The scenario hazard analysis utilized the best available geologic and seismological information as well as composite source model (i.e., ground motion simulation) to derive ground motion hazards in terms of acceleration time histories, peak values (e.g., peak ground acceleration and peak ground velocity), and response spectra. This study confirms that Tianshui is facing significant seismic hazard, and certain mitigation measures, such as better seismic design for buildings and other structures, should be developed and implemented. This study shows that PGA of 0.3 g (equivalent to Chinese intensity VIII) should be considered for seismic design of general building and PGA of 0.4 g (equivalent to Chinese intensity IX) for seismic design of critical facility in Tianshui.

A Suite of Alternative Ground-Motion Models (GMMs) for Israel

2021 ◽  
Author(s):  
Soumya Kanti Maiti ◽  
Gony Yagoda-Biran ◽  
Ronnie Kamai
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Empirical Data ◽  
Epistemic Uncertainty ◽  
Ground Motions ◽  
Plate Boundary ◽  
Strong Motion ◽  
Engineering Applications ◽  
Motion Models ◽  
Ground Motion Models

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.

scholarly journals Seismic hazard evaluation

2000 ◽  
Vol 33 (3) ◽  
pp. 371-386 ◽  
Author(s):  
Paul Somerville
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Strong Motion ◽  
Earthquake Source ◽  
Hazard Evaluation ◽  
Data Set ◽  
Motion Models ◽  
The Past ◽  
Ground Motion Models

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.

Sign in / Sign up

Export Citation Format

Share Document