Comparisons of the NGA Ground-Motion Relations

2008 ◽  
Vol 24 (1) ◽  
pp. 45-66 ◽  
Author(s):  
Norman Abrahamson ◽  
Gail Atkinson ◽  
David Boore ◽  
Yousef Bozorgnia ◽  
Kenneth Campbell ◽  
...  
Keyword(s):  
Site Response ◽  
Strike Slip ◽  
Data Sets ◽  
Sediment Depth ◽  
Long Period ◽  
Crustal Earthquakes ◽  
Nonlinear Site Response ◽  
Soil Sediment ◽  
Active Tectonic ◽  
Standard Deviations

The data sets, model parameterizations, and results from the five NGA models for shallow crustal earthquakes in active tectonic regions are compared. A key difference in the data sets is the inclusion or exclusion of aftershocks. A comparison of the median spectral values for strike-slip earthquakes shows that they are within a factor of 1.5 for magnitudes between 6.0 and 7.0 for distances less than 100 km. The differences increase to a factor of 2 for M5 and M8 earthquakes, for buried ruptures, and for distances greater than 100 km. For soil sites, the differences in the modeling of soil/sediment depth effects increase the range in the median long-period spectral values for M7 strike-slip earthquakes to a factor of 3. The five models have similar standard deviations for M6.5-M7.5 earthquakes for rock sites and for soil sites at distances greater than 50 km. Differences in the standard deviations of up to 0.2 natural log units for moderate magnitudes at all distances and for large magnitudes at short distances result from the treatment of the magnitude dependence and the effects of nonlinear site response on the standard deviation.

NGA-West2 Equations for Predicting Vertical-Component PGA, PGV, and 5%-Damped PSA from Shallow Crustal Earthquakes

2016 ◽  
Vol 32 (2) ◽  
pp. 1005-1031 ◽  
Author(s):  
Jonathan P. Stewart ◽  
David M. Boore ◽  
Emel Seyhan ◽  
Gail M. Atkinson
Keyword(s):  
Site Response ◽  
Vertical Component ◽  
Site Amplification ◽  
Intensity Measures ◽  
Global Database ◽  
Crustal Earthquakes ◽  
Anelastic Attenuation ◽  
Nonlinear Site Response ◽  
Active Tectonic ◽  
Geometric Spreading

We present ground motion prediction equations (GMPEs) for computing natural log means and standard deviations of vertical-component intensity measures (IMs) for shallow crustal earthquakes in active tectonic regions. The equations were derived from a global database with M 3.0–7.9 events. The functions are similar to those for our horizontal GMPEs. We derive equations for the primary M- and distance-dependence of peak acceleration, peak velocity, and 5%-damped pseudo-spectral accelerations at oscillator periods between 0.01–10 s. We observe pronounced M-dependent geometric spreading and region-dependent anelastic attenuation for high-frequency IMs. We do not observe significant region-dependence in site amplification. Aleatory uncertainty is found to decrease with increasing magnitude; within-event variability is independent of distance. Compared to our horizontal-component GMPEs, attenuation rates are broadly comparable (somewhat slower geometric spreading, faster apparent anelastic attenuation), VS30-scaling is reduced, nonlinear site response is much weaker, within-event variability is comparable, and between-event variability is greater.

Summary of the Abrahamson & Silva NGA Ground-Motion Relations

2008 ◽  
Vol 24 (1) ◽  
pp. 67-97 ◽  
Author(s):  
Norman Abrahamson ◽  
Walter Silva
Keyword(s):  
Standard Deviation ◽  
Ground Motion ◽  
Site Response ◽  
Hanging Wall ◽  
Site Location ◽  
Crustal Earthquakes ◽  
Nonlinear Site Response ◽  
Short Period ◽  
Standard Deviations ◽  
Improved Model

Empirical ground-motion models for the rotation-independent average horizontal component from shallow crustal earthquakes are derived using the PEER NGA database. The model is applicable to magnitudes 5–8.5, distances 0–200 km, and spectral periods of 0–10 sec. In place of generic site categories (soil and rock), the site is parameterized by average shear-wave velocity in the top 30 m ( VS30) and the depth to engineering rock (depth to VS=1000 m/s). In addition to magnitude and style-of-faulting, the source term is also dependent on the depth to top-of-rupture: for the same magnitude and rupture distance, buried ruptures lead to larger short-period ground motions than surface ruptures. The hanging-wall effect is included with an improved model that varies smoothly as a function of the source properties (M, dip, depth), and the site location. The standard deviation is magnitude dependent with smaller magnitudes leading to larger standard deviations. The short-period standard deviation model for soil sites is also distant-dependent due to nonlinear site response, with smaller standard deviations at short distances.

Kappa (κ) in the 2011 Great East Japan Earthquake

2020 ◽  
Vol 14 (06) ◽  
pp. 2050024
Author(s):  
Zhengru Tao ◽  
Xinyan Wang ◽  
Baihui Zhu ◽  
Tao Shang
Keyword(s):  
High Frequency ◽  
Site Response ◽  
Epicentral Distance ◽  
Soft Soil ◽  
Statistical Significance ◽  
Great East Japan Earthquake ◽  
Propagation Path ◽  
Data Sets ◽  
Borehole Data ◽  
Nonlinear Site Response

Kappa ([Formula: see text]) describes the amplitude decay of acceleration Fourier spectrum at high frequencies. Using the records of K-NET and KiK-net stations during the mainshock of the 2011 Great East Japan Earthquake, we examine if the typical measurement method of [Formula: see text] can be extended to this size of event and how propagation path and site condition affect [Formula: see text]. The strength of the linear relationship between epicentral distance and [Formula: see text] is the most apparent in the KiK-net borehole data; for other data sets, the statistical significance of the best-fitting logarithmic model is more tenuous. Our study on site effects reveals that high-frequency amplitudes diminish about 20% at soft soil stations than they do at hard rock stations. The effect on high-frequency filters is around diminution in most cases. And, the effect of nonlinear site response on [Formula: see text] values can be observed.

An NGA-West2 Empirical Model for Estimating the Horizontal Spectral Values Generated by Shallow Crustal Earthquakes

2014 ◽  
Vol 30 (3) ◽  
pp. 1155-1177 ◽  
Author(s):  
I. M. Idriss
Keyword(s):  
Empirical Model ◽  
Site Response ◽  
Earthquake Ground Motion ◽  
Model Parameters ◽  
Motion Data ◽  
Crustal Earthquakes ◽  
Nonlinear Site Response ◽  
Average Shear ◽  
Recorded Data ◽  
A Site

An empirical model for estimating the horizontal pseudo-absolute spectral accelerations (PSA) generated by shallow crustal earthquakes was published in 2008 using the recorded earthquake ground motion data collected and documented as part of the original Next Generation Attenuation (NGA) project. A significant number of additional recordings were collected over the past three years, and the 2008 model has been revised using the new data and is presented in this paper. The model was again selected to be simple, and the model parameters were estimated using the expanded database. The revised model incorporates V S30 as an independent variable because, with the expanded database, it was found that V S30 was required to be included as an independent parameter to allow for a reasonably unbiased fit to the recorded data. It is noted that V S30 is not being used to account for nonlinear site response, but strictly to allow for a better fit to the data. These parameters are presented for sites with an average shear wave velocity in the upper 30 m, V S30, for sites with V S30 ≥ 450 m/s. Parameters for sites with V S30 < 450 m/s are not included in this paper. For a site with V S30 = 450 m/s, there is an overall increase in PGA averaging about 50% over a distance of about 100 km using the 2013 model in comparison to the 2008 model. On the other hand, for a site with V S30 = 900 m/s, there is an overall decrease of about 10% using the 2013 model in comparison to the 2008 model.

Ground Motion Prediction Equations for the Vertical Ground Motion Component Based on the NGA-W2 Database

2017 ◽  
Vol 33 (2) ◽  
pp. 499-528 ◽  
Author(s):  
Zeynep Gülerce ◽  
Ronnie Kamai ◽  
Norman A. Abrahamson ◽  
Walter J. Silva
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Vertical Component ◽  
Weighted Average ◽  
Motion Models ◽  
Nonlinear Site Response ◽  
Vertical Ground Motion ◽  
Vertical Ground ◽  
Standard Deviations ◽  
Ground Motion Models

Empirical ground motion models for the vertical component from shallow crustal earthquakes in active tectonic regions are derived using the PEER NGA-West2 database. The model is applicable to magnitudes 3.0–8.0, distances of 0–300 km, and spectral periods of 0–10 s. The model input parameters are the same as used by Abrahamson et al. (2014) except that the nonlinear site response and depth to bedrock effects are evaluated but found to be insignificant. Regional differences in large distance attenuation and site amplification scaling between California, Japan, China, Taiwan, Italy, and the Middle East are included. Scaling for the hanging-wall effect is incorporated using the constraints from numerical simulations by Donahue and Abrahamson (2014) . The standard deviation is magnitude dependent with smaller magnitudes leading to larger standard deviations at short periods but smaller standard deviations at long periods. The vertical ground motion model developed in this study can be paired with the horizontal component model proposed by Abrahamson et al. (2014) to produce a V/H ratio. For applications where the horizontal spectrum is derived from the weighted average of several horizontal ground motion models, a V/H model derived directly from the V/H data (such as Gülerce and Abrahamson 2011 ) should be preferred.

Summary of the ASK14 Ground Motion Relation for Active Crustal Regions

2014 ◽  
Vol 30 (3) ◽  
pp. 1025-1055 ◽  
Author(s):  
Norman A. Abrahamson ◽  
Walter J. Silva ◽  
Ronnie Kamai
Keyword(s):  
Ground Motion ◽  
Regional Differences ◽  
Hanging Wall ◽  
Nonlinear Effects ◽  
Motion Models ◽  
Crustal Earthquakes ◽  
Active Tectonic ◽  
Standard Deviations ◽  
Ground Motion Models ◽  
Directivity Effects

Empirical ground motion models for the average horizontal component from shallow crustal earthquakes in active tectonic regions are derived using the PEER NGA-West2 database. The model is applicable to magnitudes 3.0–8.5, distances 0–300 km, and spectral periods of 0–10 s. The model input parameters are the same as those used by Abrahamson and Silva (2008) , with the following exceptions: the loading level for nonlinear effects is based on the spectral acceleration at the period of interest rather than the PGA; and the distance scaling for hanging wall (HW) effects off the ends of the rupture includes a dependence on the source-to-site azimuth. Regional differences in large-distance attenuation and V S30 scaling between California, Japan, China, and Taiwan are included. The scaling for the HW effect is improved using constraints from numerical simulations. The standard deviation is magnitude-dependent, with smaller magnitudes leading to larger standard deviations at short periods, but smaller standard deviations at long periods. Directivity effects are not included through explicit parameters, but are captured through the variability of the empirical data.

Integrating Effects of Source-Dependent Factors on Sediment-Depth Scaling of Additional Site Amplification to Ground-Motion Prediction Equation

2021 ◽  
Author(s):  
Hongwei Wang ◽  
Chunguo Li ◽  
Ruizhi Wen ◽  
Yefei Ren
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Focal Depth ◽  
Site Amplification ◽  
Prediction Equation ◽  
Sediment Depth ◽  
Long Period ◽  
Crustal Earthquakes ◽  
Additional Site ◽  
Kanto Basin

ABSTRACT It is crucial to include additional site amplification effects resulting from the thick sediment on ground motions in the reliable assessment for seismic hazard in sedimentary basins. Ground-motion residual analysis with respect to ground-motion prediction equation is performed to evaluate additional site amplifications at over 200 K-NET stations within and around Kanto basin. We first investigate the potential effects on additional site amplifications resulted from the sediment depth and several source-dependent factors. Results reveal that source-to-site distance, focal depth, and source azimuth all have nonnegligible effects on additional site amplifications, especially the focal depth. Thick sedimentary sites amplify long-period ground motions from distant earthquakes more strongly than those from local earthquakes. Ground motions from shallow crustal earthquakes generally experience much stronger amplifications than those from those deep subduction earthquakes, much more predominant for long-period ground motions (&gt;1.0 s) at thick sedimentary sites. Meanwhile, we develop the empirical model after integrating contributions from sediment depth, source-to-site distance, and focal depth for predicting additional site amplification effects. Considering the typical case of the distant shallow crustal earthquakes, additional site amplifications at thick sedimentary sites within Kanto basin generally show an increasing trend with the oscillation period increased, whereas they are generally characterized by a decreasing trend at shallow sedimentary sites outside the basin. The mean additional site amplification is up to about 2.0 within Kanto basin, whereas 0.5–0.65 outside Kanto basin, for ground motions at oscillation periods of 2.0–5.0 s. Mean amplifications within Kanto basin are about 3.5 times larger than those outside the basin for long-period ground motions at 2.0–5.0 s. Sites northeast to Kanto basin show the largest amplifications up to about 3.0 at periods of 0.15 and 5.0 s, which may be resulted from the basin edge effects.

Ground Motion Site Amplification Factors for Sites Located within the Mississippi Embayment with Consideration of Deep Soil Deposits

2015 ◽  
Vol 31 (2) ◽  
pp. 699-722 ◽  
Author(s):  
Mojtaba Malekmohammadi ◽  
Shahram Pezeshk
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Site Amplification ◽  
Sediment Depth ◽  
Deep Soil ◽  
Mississippi Embayment ◽  
Soil Response ◽  
Amplification Factors ◽  
Nonlinear Site Response ◽  
Soil Deposits

In this study, site amplification factors for the deep soil deposits of the Mississippi embayment are computed using a nonlinear site response analysis program first to develop a model for nonlinear soil response for possible use by ground motion developers and second to address site amplification estimation. The effects of geology, sediment depth, and average shear wave velocity at the upper 30 m of soil ranging 180–800 m/s, as well as the effect of peak ground acceleration at the bedrock on nonlinear ground motion amplification for the upper embayment, are investigated. The site response computations cover various site conditions, sediment depth of 70–750 m, and peak acceleration of input rock motions of 0.01–0.90 g. The amplification (or de-amplification) at various frequencies implied by the sediment depth is greater than that implied just by site classification of the top 30 m of soil.

Simulation-based site amplification model for shallow bedrock sites in Korea

2021 ◽  
pp. 875529302098198
Author(s):  
Muhammad Aaqib ◽  
Duhee Park ◽  
Muhammad Bilal Adeel ◽  
Youssef M A Hashash ◽  
Okan Ilhan
Keyword(s):  
Linear Models ◽  
Site Response ◽  
Site Amplification ◽  
One Dimensional ◽  
Nonlinear Component ◽  
Nonlinear Site Response ◽  
Simulation Based ◽  
Linear And Nonlinear ◽  
Input Motion ◽  
Nonlinear Components

A new simulation-based site amplification model for shallow sites with thickness less than 30 m in Korea is developed. The site amplification model consists of linear and nonlinear components that are developed from one-dimensional linear and nonlinear site response analyses. A suite of measured shear wave velocity profiles is used to develop corresponding randomized profiles. A VS30 scaled linear amplification model and a model dependent on both VS30 and site period are developed. The proposed linear models compare well with the amplification equations developed for the western United States (WUS) at short periods but show a distinct curved bump between 0.1 and 0.5 s that corresponds to the range of site natural periods of shallow sites. The response at periods longer than 0.5 s is demonstrated to be lower than those of the WUS models. The functional form widely used in both WUS and central and eastern North America (CENA), for the nonlinear component of the site amplification model, is employed in this study. The slope of the proposed nonlinear component with respect to the input motion intensity is demonstrated to be higher than those of both the WUS and CENA models, particularly for soft sites with VS30 < 300 m/s and at periods shorter than 0.2 s. The nonlinear component deviates from the models for generic sites even at low ground motion intensities. The comparisons highlight the uniqueness of the amplification characteristics of shallow sites that a generic site amplification model is unable to capture.

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