Comparison of NGA-West2 GMPEs

2014 ◽  
Vol 30 (3) ◽  
pp. 1179-1197 ◽  
Author(s):  
Nick Gregor ◽  
Norman A. Abrahamson ◽  
Gail M. Atkinson ◽  
David M. Boore ◽  
Yousef Bozorgnia ◽  
...  
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Hanging Wall ◽  
Model Parameters ◽  
Data Sets ◽  
Similar Increase ◽  
Regional Data ◽  
Large Magnitude ◽  
Aleatory Variability ◽  
Attenuation Rate

A presentation of the model parameters and comparison of the median ground-motion values from the NGA-West2 GMPEs is presented for a suite of deterministic cases. In general, the median ground motions are similar, within a factor of about 1.5–2.0 for 5 < M < 7 and distances between 10–100 km. Differences increase (on the order of 2–3) for large-magnitude (M > 8) earthquakes at large distances ( R > 100–200 km) and for close distances ( R < 10 km). A similar increase is observed for hanging-wall sites, and slightly larger differences are observed for soil sites as opposed to rock sites. Regionalization of four of the GMPEs yields similar attenuation rate adjustments based on the different regional data sets. All five GMPE aleatory variability models are a function of magnitude with higher overall standard deviations values for the smaller magnitudes when compared to the large-magnitude events.

An NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra

2008 ◽  
Vol 24 (1) ◽  
pp. 173-215 ◽  
Author(s):  
BrianS-J. Chiou ◽  
Robert R. Youngs
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Hanging Wall ◽  
Response Spectra ◽  
Horizontal Component ◽  
Smooth Functions ◽  
Soil Response ◽  
New Model ◽  
Crustal Earthquakes ◽  
Aleatory Variability

We present a model for estimating horizontal ground motion amplitudes caused by shallow crustal earthquakes occurring in active tectonic environments. The model provides predictive relationships for the orientation-independent average horizontal component of ground motions. Relationships are provided for peak acceleration, peak velocity, and 5-percent damped pseudo-spectral acceleration for spectral periods of 0.01 to 10 seconds. The model represents an update of the relationships developed by Sadigh et. al. (1997) and incorporates improved magnitude and distance scaling forms as well as hanging-wall effects. Site effects are represented by smooth functions of average shear wave velocity of the upper 30 m ( VS30) and sediment depth. The new model predicts median ground motion that is similar to Sadigh et. al. (1997) at short spectral period, but lower ground motions at longer periods. The new model produces slightly lower ground motions in the distance range of 10 to 50 km and larger ground motions at larger distances. The aleatory variability in ground motion amplitude was found to depend upon earthquake magnitude and on the degree of nonlinear soil response, For large magnitude earthquakes, the aleatory variability is larger than found by Sadigh et. al. (1997).

scholarly journals Simulation of non-stationary stochastic ground motions based on recent Italian earthquakes

2021 ◽  
Author(s):  
Fabio Sabetta ◽  
Antonio Pugliese ◽  
Gabriele Fiorentino ◽  
Giovanni Lanzano ◽  
Lucia Luzi
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Strong Motion ◽  
Stochastic Simulations ◽  
Model Parameters ◽  
Motion Model ◽  
Arias Intensity ◽  
Time Frequency ◽  
Ground Motion Model ◽  
Ground Motion Records

AbstractThis work presents an up-to-date model for the simulation of non-stationary ground motions, including several novelties compared to the original study of Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996). The selection of the input motion in the framework of earthquake engineering has become progressively more important with the growing use of nonlinear dynamic analyses. Regardless of the increasing availability of large strong motion databases, ground motion records are not always available for a given earthquake scenario and site condition, requiring the adoption of simulated time series. Among the different techniques for the generation of ground motion records, we focused on the methods based on stochastic simulations, considering the time- frequency decomposition of the seismic ground motion. We updated the non-stationary stochastic model initially developed in Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996) and later modified by Pousse et al. (Bull Seism Soc Am 96:2103–2117, 2006) and Laurendeau et al. (Nonstationary stochastic simulation of strong ground-motion time histories: application to the Japanese database. 15 WCEE Lisbon, 2012). The model is based on the S-transform that implicitly considers both the amplitude and frequency modulation. The four model parameters required for the simulation are: Arias intensity, significant duration, central frequency, and frequency bandwidth. They were obtained from an empirical ground motion model calibrated using the accelerometric records included in the updated Italian strong-motion database ITACA. The simulated accelerograms show a good match with the ground motion model prediction of several amplitude and frequency measures, such as Arias intensity, peak acceleration, peak velocity, Fourier spectra, and response spectra.

Evaluation of Building Collapse Risk and Drift Demands by Nonlinear Structural Analyses Using Conventional Hazard Analysis versus Direct Simulation with CyberShake Seismograms

2019 ◽  
Vol 109 (5) ◽  
pp. 1812-1828 ◽  
Author(s):  
Nenad Bijelić ◽  
Ting Lin ◽  
Gregory G. Deierlein
Keyword(s):  
Los Angeles ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Tall Buildings ◽  
Direct Analysis ◽  
Large Magnitude ◽  
Deep Basin ◽  
Building Collapse ◽  
Nonlinear Structural

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.

Update of the Chiou and Youngs NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra

2014 ◽  
Vol 30 (3) ◽  
pp. 1117-1153 ◽  
Author(s):  
Brian S.-J. Chiou ◽  
Robert R. Youngs
Keyword(s):  
Ground Motion ◽  
Hanging Wall ◽  
Response Spectra ◽  
Rupture Directivity ◽  
Crustal Earthquakes ◽  
Aleatory Variability ◽  
Source Distance ◽  
Active Tectonic ◽  
Peak Ground Motion ◽  
Horizontal Ground Motion

We present an update to our 2008 NGA model for predicting horizontal ground motion amplitudes caused by shallow crustal earthquakes occurring in active tectonic environments. The update is based on analysis of the greatly expanded NGA-West2 ground motion database and numerical simulations. The updated model contains minor adjustments to our 2008 functional form related to style of faulting effects, hanging wall effects, scaling with the depth to top of rupture, scaling with sediment thickness, and the inclusion of additional terms for the effects of fault dip and rupture directivity. In addition, we incorporate regional differences in far-source distance attenuation and site effects between California and other active tectonic regions. Compared to our 2008 NGA model, the predicted medians by the updated model are similar for M > 7 and are lower for M < 5. The aleatory variability is larger than that obtained in our 2008 model.

An efficient algorithm to simulate hazard-targeted site-based synthetic ground motions

2020 ◽  
pp. 875529302097096
Author(s):  
Jawad Fayaz ◽  
Sarah Azar ◽  
Mayssa Dabaghi ◽  
Farzin Zareian
Keyword(s):  
Ground Motion ◽  
Efficient Algorithm ◽  
Ground Motions ◽  
Model Parameters ◽  
Graphic User Interface ◽  
Forward Selection ◽  
Intensity Measure ◽  
Input Event ◽  
Predictive Relations ◽  
Simulated Ground Motions

This study presents an efficient algorithm that can be used to simulate ground motion waveforms using the site-based approach developed by Dabaghi and Der Kiureghian, and Rezaeian and Der Kiureghian that not only correspond to a specified seismic scenario (e.g. magnitude, distance, site conditions) but are also certain to achieve a target ground motion intensity measure within a narrow range. The suggested algorithm alleviates the need to scale simulated ground motions generated using the above-mentioned site-based approach; the resulting hazard-targeted simulated ground motions have consistent amplitude and time- and frequency-domain characteristics, which are required for proper seismic demand analysis of structures. The proposed algorithm takes as input a set of seismic Event Parameters and the target hazard intensity measure [Formula: see text] and generates a corresponding set of Model Parameters (i.e. input to the site-based ground motion simulation model). These Model Parameters are then used to simulate ground motion waveforms that not only represent the set of input Event Parameters ( Mw, Rrup, Vs30) but also maintain the target [Formula: see text]. To generate the set of Model Parameters, predictive relations between the Model Parameters and [Formula: see text] of ground motions are developed. Among the Model Parameters, the ones classified as important by statistical procedures (such as Random Forests, Forward Selection) are used to develop the predictive relations. The developed relations are then validated against a large dataset of recorded ground motions. The final implementation is provided in terms of graphic-user interface (GUI) called “Hazard-Targeted Time-Series Simulator” ( HATSim), which efficiently simulates site-based ground motions with minimum inputs.

Site-Specific Characterization of Earthquake Ground Motions: Papua New Guinea Case Study

2020 ◽  
Author(s):  
Mark Novakovic ◽  
Emrah Yenier ◽  
Andrew Hovey ◽  
Joseph Quinn ◽  
Benjamin Witten
Keyword(s):  
Standard Deviation ◽  
Papua New Guinea ◽  
Ground Motion ◽  
Epistemic Uncertainty ◽  
Hazard Analysis ◽  
Ground Motions ◽  
New Guinea ◽  
Source Type ◽  
Aleatory Variability ◽  
Single Station

&lt;p&gt;A seismic hazard analysis was conducted for a site in Papua New Guinea which is located in a seismically-active region that experiences frequent large earthquakes generated by crustal and subduction sources. &amp;#160;A suite of ground motion prediction equations (GMPEs) was developed for each source type (crustal, interface and in-slab) using the scaled-backbone approach. &amp;#160;To this end, a ground-motion database consisting of events of 4.0&lt;Mw&lt;8.0 was compiled from available local and regional monitoring stations. &amp;#160;Ground motions were classified based on the source type and converted to a common reference site condition. &amp;#160;The site-corrected motions were compared against alternative GMPEs to examine residual trends between observed and predicted amplitudes.&amp;#160; A backbone model that represents the best estimate of the median ground motions for each source type was selected. &amp;#160;The backbone models were then adjusted to the median of the ground motions observed at the study site.&lt;/p&gt;&lt;p&gt;The epistemic uncertainty in median predictions was modeled using a logic-tree approach, where the distribution of potential median predictions is approximated by a lower, central and upper model. &amp;#160;The central model is represented by the site-adjusted backbone model; it was scaled to define the lower and upper branches. &amp;#160;The scaling factor was determined considering: (i) the standard deviation in median prediction of alternative GMPEs; and (ii) epistemic uncertainties recommended in other studies. &amp;#160;The available data were insufficient to model aleatory variability with confidence; therefore, the standard deviation of observed motions in data-rich regions is used for guidance. &amp;#160;Two alternative aleatory variability models (ergodic and single-station sigma) adopted from other studies are recommended.&lt;/p&gt;

scholarly journals Ground-motion relations for eastern North America

1995 ◽  
Vol 85 (1) ◽  
pp. 17-30 ◽  
Author(s):  
Gail M. Atkinson ◽  
David M. Boore
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Model Parameters ◽  
Eastern North America ◽  
Motion Model ◽  
Ground Acceleration ◽  
Ground Motion Model ◽  
Definition Of ◽  
Validation Of Results

Abstract Predictive relations are developed for ground motions from eastern North American earthquakes of 4.0 ≦ M ≦ 7.25 at distances of 10 ≦ R ≦ 500 km. The predicted parameters are response spectra at frequencies of 0.5 to 20 Hz, and peak ground acceleration and velocity. The predictions are derived from an empirically based stochastic ground-motion model. The relations differ from previous work in the improved empirical definition of input parameters and empirical validation of results. The relations are in demonstrable agreement with ground motions from earthquakes of M 4 to 5. There are insufficient data to adequately judge the relations at larger magnitudes, although they are consistent with data from the Saguenay (M 5.8) and Nahanni (M 6.8) earthquakes. The underlying model parameters are constrained by empirical data for events as large as M 6.8.

Effects of the hanging wall and footwall on ground motions recorded during the Northridge earthquake

1996 ◽  
Vol 86 (1B) ◽  
pp. S93-S99
Author(s):  
N. A. Abrahamson ◽  
P. G. Somerville
Keyword(s):  
Ground Motion ◽  
Empirical Model ◽  
Empirical Data ◽  
Ground Motions ◽  
Hanging Wall ◽  
Systematic Difference ◽  
Wall Effect ◽  
Northridge Earthquake ◽  
Distance Range ◽  
Hanging Wall Effect

Abstract Systematic differences in ground motion on the hanging wall and footwall during the Northridge earthquake are evaluated using empirical data. An empirical model for the hanging-wall effect is developed for the Northridge earthquake. This empirical model results in up to a 50% increase in peak horizontal accelerations on the hanging wall over the distance range of 10 to 20 km relative to the median attenuation for the Northridge earthquake. In contrast, the peak accelerations on the footwall are not significantly different from the median attenuation over this distance range. Recordings from other reverse events show a similar trend of an increase in the peak accelerations on the hanging wall, indicating that this systematic difference in hanging-wall peak accelerations is likely to be observed in future reverse events.

NGA-East Ground-Motion Characterization model part I: Summary of products and model development

2021 ◽  
Vol 37 (1_suppl) ◽  
pp. 1231-1282
Author(s):  
Christine A Goulet ◽  
Yousef Bozorgnia ◽  
Nicolas Kuehn ◽  
Linda Al Atik ◽  
Robert R Youngs ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Ground Motion ◽  
Peer Review Process ◽  
Epistemic Uncertainty ◽  
Ground Motions ◽  
Hanging Wall ◽  
Analysis Committee ◽  
Ground Acceleration ◽  
Single Station ◽  
Motion Characterization

In this article, we present an overview of the research project NGA-East, Next Generation Attenuation for Central and Eastern North America (CENA), and summarize the key methodology and products. The project was tasked with developing a new ground motion characterization (GMC) model for CENA. The final NGA-East GMC model includes a set of 17 median ground motion models (GMMs) for peak ground acceleration and velocity (PGA, PGV) and response spectral ordinates for periods ranging from 0.01 to 10 s. The NGA-East GMMs are applicable to horizontal components of ground motions on very hard rock, for the moment magnitude range of 4.0–8.2, and distances of up to 1500 km. The aleatory standard deviations of GMMs are also provided for site-specific analysis (single-station standard deviation) and for general probabilistic seismic hazard analyses (PSHA) applications (ergodic standard deviation). In addition, adjustment factors are provided for source depth and hanging-wall effects, as well as for hazard computations at sites in the Gulf Coast Region. During the course of the project, several innovative technologies were developed and implemented to increase the transparency and repeatability of the GMC building process. This involved expanding on a set of candidate median GMMs to define and capture an appropriate range of epistemic uncertainty in ground motions. We also developed a new approach for modeling the aleatory variability that was completely independent of the median GMMs. The development made extensive use of the CENA database but also borrowed data from other parts of the world when relevant and led to an integrated suite of models. Through this repeatable process, epistemic uncertainty could be quantified more objectively than before, relying less on expert opinion. The NGA-East project went through a comprehensive Seismic Senior Hazard Analysis Committee (SSHAC) Level 3 peer review process before its release.

scholarly journals Influence of the Site-Specific Component of Kappa on the Magnitude-Dependency of Within-Event Aleatory Variabilities in Ground-Motion Models

2020 ◽  
Vol 92 (1) ◽  
pp. 238-245
Author(s):  
Christopher Brooks ◽  
John Douglas
Keyword(s):  
Ground Motion ◽  
Stress Drop ◽  
Ground Motions ◽  
Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard Assessment ◽  
Specific Component ◽  
Site Specific ◽  
Motion Models ◽  
Earthquake Ground Motions ◽  
Aleatory Variability

Abstract The aleatory-variability component (standard deviation) of a ground motion has a large influence on results of a probabilistic seismic hazard assessment. kappa, a measure of high-frequency attenuation, has site- and record-specific effects that have been suggested as reasons for observing heteroscedastic aleatory variability within earthquake ground motions. Specifically, kappa has been proposed as a reason why ground motions from small earthquakes are more variable than those from large earthquakes, which is modeled by magnitude-dependent within-event standard deviations in ground-motion prediction equations (GMPEs). In this study, we use ground motions simulated using the stochastic method to examine the influence of the site-specific component of kappa on aleatory variability of earthquake ground motions and examine the hypothesis that this could be a cause of the observed heteroscedasticity in this variability. We consider simulations with both fixed and continuous stress drop distributions and the site-specific component of kappa to demonstrate that variation in the stress drop parameter contributes minimally to magnitude-dependency, unlike the site-specific component of kappa, which causes significant magnitude-dependency. Variation in the site-specific component of kappa is, therefore, proposed to be at least partially responsible for the magnitude-dependency captured in the aleatory-variability components of some recent GMPEs. It is found, however, that the expected impact of the site-specific component of kappa on aleatory variability is much greater than modeled in these GMPEs, which suggests that there could be a mitigating effect that is not captured within the simulations (e.g., correlated inputs to the simulations).

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