The 2019 Ridgecrest, California, Earthquake Sequence Ground Motions: Processed Records and Derived Intensity Metrics

2020 ◽  
Vol 91 (4) ◽  
pp. 2010-2023 ◽  
Author(s):  
John M. Rekoske ◽  
Eric M. Thompson ◽  
Morgan P. Moschetti ◽  
Mike G. Hearne ◽  
Brad T. Aagaard ◽  
...  
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Earthquake Sequence ◽  
Motion Processing ◽  
Data Set ◽  
Multiple Data ◽  
Wide Range ◽  
Ground Motion Records ◽  
Motion Metrics ◽  
Processing Steps

Abstract Following the 2019 Ridgecrest, California, earthquake sequence, we compiled ground-motion records from multiple data centers and processed these records using newly developed ground-motion processing software that performs quality assurance checks, performs standard time series processing steps, and computes a wide range of ground-motion metrics. In addition, we compute station and waveform metrics such as the time-averaged shear-wave velocity to 30 m depth (VS30), finite-rupture distances, and spectral accelerations. This data set includes 22,708 records from 133 events from 4 July 2019 (UTC) to 18 October 2019 with a magnitude range from 3.6 to 7.1. We expect that the rapid collection and dissemination of this information will facilitate detailed studies of these ground motions. In this article, we describe the data selection, processing steps, and how to access the data.

scholarly journals Ground motions in urban Los Angeles from the 2019 Ridgecrest earthquake sequence

2021 ◽  
pp. 875529302110039
Author(s):  
Filippos Filippitzis ◽  
Monica D Kohler ◽  
Thomas H Heaton ◽  
Robert W Graves ◽  
Robert W Clayton ◽  
...  
Keyword(s):  
Los Angeles ◽  
Ground Motion ◽  
Ground Motions ◽  
Earthquake Sequence ◽  
Motion Prediction ◽  
Ground Motion Prediction Equations ◽  
Prediction Equations ◽  
Ground Motion Prediction ◽  
Velocity Models ◽  
Spectral Accelerations

We study ground-motion response in urban Los Angeles during the two largest events (M7.1 and M6.4) of the 2019 Ridgecrest earthquake sequence using recordings from multiple regional seismic networks as well as a subset of 350 stations from the much denser Community Seismic Network. In the first part of our study, we examine the observed response spectral (pseudo) accelerations for a selection of periods of engineering significance (1, 3, 6, and 8 s). Significant ground-motion amplification is present and reproducible between the two events. For the longer periods, coherent spectral acceleration patterns are visible throughout the Los Angeles Basin, while for the shorter periods, the motions are less spatially coherent. However, coherence is still observable at smaller length scales due to the high spatial density of the measurements. Examining possible correlations of the computed response spectral accelerations with basement depth and Vs30, we find the correlations to be stronger for the longer periods. In the second part of the study, we test the performance of two state-of-the-art methods for estimating ground motions for the largest event of the Ridgecrest earthquake sequence, namely three-dimensional (3D) finite-difference simulations and ground motion prediction equations. For the simulations, we are interested in the performance of the two Southern California Earthquake Center 3D community velocity models (CVM-S and CVM-H). For the ground motion prediction equations, we consider four of the 2014 Next Generation Attenuation-West2 Project equations. For some cases, the methods match the observations reasonably well; however, neither approach is able to reproduce the specific locations of the maximum response spectral accelerations or match the details of the observed amplification patterns.

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.

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.

Modeling nonlinear site effects in physics-based ground motion simulations of the 2010–2011 Canterbury earthquake sequence

2020 ◽  
Vol 36 (2) ◽  
pp. 856-879 ◽  
Author(s):  
Christopher A de la Torre ◽  
Brendon A Bradley ◽  
Robin L Lee
Keyword(s):  
Wave Propagation ◽  
Ground Motion ◽  
Site Effects ◽  
Ground Motions ◽  
Site Amplification ◽  
Earthquake Sequence ◽  
Response Analysis ◽  
Site Specific ◽  
Ground Motion Simulations ◽  
Empirical Ground

This study examines the performance of nonlinear total stress one-dimensional (1D) wave propagation site response analysis for modeling site effects in physics-based ground motion simulations of the 2010–2011 Canterbury, New Zealand earthquake sequence. This approach explicitly models three-dimensional (3D) ground motion phenomena at the regional scale, and detailed site effects at the local scale. The approach is compared with a more commonly used empirical VS30-based method of computing site amplification for simulated ground motions, as well as prediction via an empirical ground motion model. Site-specific ground response analysis is performed at 20 strong motion stations in Christchurch for 11 earthquakes with 4.7≤ MW≤7.1. When compared with the VS30-based approach, the wave propagation analysis reduces both overall model bias and uncertainty in site-to-site residuals at the fundamental period, and significantly reduces systematic residuals for soft or “atypical” sites that exhibit strong site amplification. The comparable performance in ground motion prediction between the physics-based simulation method and empirical ground motion models suggests the former is a viable approach for generating site-specific ground motions for geotechnical and structural response history analyses.

Repeatable Source, Path, and Site Effects from the 2019 M 7.1 Ridgecrest Earthquake Sequence

2020 ◽  
Vol 110 (4) ◽  
pp. 1530-1548 ◽  
Author(s):  
Grace A. Parker ◽  
Annemarie S. Baltay ◽  
John Rekoske ◽  
Eric M. Thompson
Keyword(s):  
Los Angeles ◽  
Ground Motion ◽  
Site Response ◽  
Ground Motions ◽  
Warning System ◽  
Site Amplification ◽  
Earthquake Sequence ◽  
Ground Acceleration ◽  
Small Magnitude ◽  
Earthquake Early Warning System

ABSTRACT We use a large instrumental dataset from the 2019 Ridgecrest earthquake sequence (Rekoske et al., 2019, 2020) to examine repeatable source-, path-, and site-specific ground motions. A mixed-effects analysis is used to partition total residuals relative to the Boore et al. (2014; hereafter, BSSA14) ground-motion model. We calculate the Arias intensity stress drop for the earthquakes and find strong correlation with our event terms, indicating that they are consistent with source processes. We look for physically meaningful trends in the partitioned residuals and test the ability of BSSA14 to capture the behavior we observe in the data. We find that BSSA14 is a good match to the median observations for M>4. However, we find bias for individual events, especially those with small magnitude and hypocentral depth≥7  km, for which peak ground acceleration is underpredicted by a factor of 2.5. Although the site amplification term captures the median site response when all sites are considered together, it does not capture variations at individual stations across a range of site conditions. We find strong basin amplification in the Los Angeles, Ventura, and San Gabriel basins. We find weak amplification in the San Bernardino basin, which is contrary to simulation-based findings showing a channeling effect from an event with a north–south azimuth. This and an additional set of ground motions from earthquakes southwest of Los Angeles suggest that there is an azimuth-dependent southern California basin response related to the orientation of regional structures when ground motion from waves traveling south–north are compared with those in the east–west direction. These findings exhibit the power of large, spatially dense ground-motion datasets and make clear that nonergodic models are a way to reduce bias and uncertainty in ground-motion estimation for applications like the U.S. Geological Survey National Seismic Hazard Model and the ShakeAlert earthquake early warning System.

A Stochastic Model for Simulating Vertical Pulseless Near-Fault Seismic Ground Motions

2021 ◽  
Author(s):  
Xi Zhong Cui ◽  
Yong Xu Liu ◽  
Han Ping Hong
Keyword(s):  
Stochastic Model ◽  
Ground Motion ◽  
Ground Motions ◽  
Time History ◽  
Structural Deformation ◽  
Time Frequency ◽  
Motion Models ◽  
Near Fault ◽  
Simulation Techniques ◽  
Ground Motion Records

ABSTRACT The vertical near-fault seismic ground-motion component can cause significant structural deformation and damage, which can be evaluated from time history analysis using actual or synthetic ground-motion records. In this study, we propose a new stochastic model for the vertical pulseless near-fault ground motions that depends on earthquake magnitude, rupture distance, and site condition. The proposed model is developed based on the time–frequency characteristics of 606 selected actual vertical record components in strike-slip earthquakes. The use and validation of the model are presented using simulated records obtained by two simulation techniques. For the validation, the statistics of time–frequency-dependent power spectral acceleration estimated from the simulated records using the proposed stochastic model are compared with those from the actual records and the ground-motion models available in the literature.

Turkey-Adjusted NGA-W1 Horizontal Ground Motion Prediction Models

2016 ◽  
Vol 32 (1) ◽  
pp. 75-100 ◽  
Author(s):  
Zeynep Gülerce ◽  
Bahadır Kargoığlu ◽  
Norman A. Abrahamson
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Prediction Models ◽  
Ground Motions ◽  
Site Amplification ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Data Set ◽  
Horizontal Ground Motion ◽  
Strong Ground

The objective of this paper is to evaluate the differences between the Next Generation Attenuation: West-1 (NGA-W1) ground motion prediction models (GMPEs) and the Turkish strong ground motion data set and to modify the required pieces of the NGA-W1 models for applicability in Turkey. A comparison data set is compiled by including strong motions from earthquakes that occurred in Turkey and earthquake metadata of ground motions consistent with the NGA-W1 database. Random-effects regression is employed and plots of the residuals are used to evaluate the differences in magnitude, distance, and site amplification scaling. Incompatibilities between the NGA-W1 GMPEs and Turkish data set in small-to-moderate magnitude, large distance, and site effects scaling are encountered. The NGA-W1 GMPEs are modified for the misfit between the actual ground motions and the model predictions using adjustments functions. Turkey-adjusted NGA-W1 models are compatible with the regional strong ground motion characteristics and preserve the well-constrained features of the global models.

Seismic assessment of a cable-stayed arch bridge under three-component orthotropic earthquake excitation

2020 ◽  
pp. 136943322094875 ◽  
Author(s):  
Salar Farahmand-Tabar ◽  
Majid Barghian
Keyword(s):  
Ground Motion ◽  
Numerical Study ◽  
Epicentral Distance ◽  
Ground Motions ◽  
Dynamic Responses ◽  
Earthquake Excitation ◽  
Arch Bridge ◽  
Stay Cables ◽  
Horizontal Ground Motion ◽  
Ground Motion Records

The occurred damages during the past significant earthquakes have proved that vertical seismic excitation has tremendous effect on bridges. Three-component earthquake excitations are preferred to resemble the earthquakes. In this article, a cable-stayed arch bridge, a new type of bridge with the hybrid system of half-through arch and stay-cables, was analyzed under a set of different earthquake excitations (more than 21 ground motion records). Both vertical and horizontal components of the ground motions were considered to act simultaneously at the bridge supports. By using different three-component earthquake excitations, the dynamic responses of the bridge, including the displacements and accelerations of the main parts of the bridge, were obtained. The effects of various parameters such as soil type, epicentral distance, spatial variation of the ground motions, and dimensional variation of the structure were investigated. The results of the numerical study indicate that the cable-stayed arch bridge subjected to both horizontal and vertical components of earthquakes are more vulnerable than those subjected to horizontal ground motion only.

Identification of Pulse Periods in Near‐Fault Ground Motions Using the HHT Method

2019 ◽  
Vol 109 (6) ◽  
pp. 2384-2398 ◽  
Author(s):  
Xiaoyu Chen ◽  
Dongsheng Wang ◽  
Rui Zhang
Keyword(s):  
Ground Motion ◽  
Time Course ◽  
Ground Motions ◽  
Flexible Structures ◽  
Peak Ground Velocity ◽  
Damage Effect ◽  
Near Fault ◽  
Long Period ◽  
Frequency Components ◽  
Ground Motion Records

Abstract Large‐amplitude and long‐period pulses are observed in velocity time histories of near‐fault ground‐motion records. The pulses in these records have significant damage effect on flexible structures due to their long‐period property; therefore, more attention should be paid to the frequency components in the ground motion. Based on the identification of frequency components in the original record, a new method based on the Hilbert–Huang transform (HHT) is proposed here. A ground‐motion record can be decomposed into several intrinsic mode functions (IMFs) that carry different frequency components by the HHT without contamination from any a prior function. Only two fixed parameters, the peak ground velocity (PGV)/peak ground acceleration (PGA) ratio and the energy change of every IMF, are used to classify pulse‐like ground‐motion records. The inherent pulses of these records can also be extracted, based on the selection of IMFs for which PGV/PGA ratios are larger than 0.12 and energy changes that are greater than 0.1. For multipulse cases, all the pulses can be captured after extracting once, and the time course of inherent pulses can also be obtained. Then, pulse periods are calculated based on the solutions of instantaneous frequency of the peak for the extracted pulses. All the periods obtained using the HHT method can be verified by the results obtained from Baker’s wavelet method. The 24 controversial records that are discussed in previous studies are examined here as well. The HHT method is a complete procedure that includes the classification of pulse‐like ground motions, the extraction of velocity pulses, and the solution of pulse periods. It works well for multipulse records, especially because it can provide the exact timing of all the inherent pulses.

Ground Motion Selection for Liquefaction Evaluation Analysis of Earthen Levees

2012 ◽  
Vol 28 (4) ◽  
pp. 1331-1351 ◽  
Author(s):  
Adda Athanasopoulos-Zekkos ◽  
Mustafa Saadi
Keyword(s):  
Ground Motion ◽  
Cross Sections ◽  
Ground Motions ◽  
Cyclic Stress ◽  
Cyclic Stress Ratio ◽  
Ground Motion Selection ◽  
Liquefaction Susceptibility ◽  
Wide Range ◽  
Dynamic Analyses ◽  
The Mean

Guidelines for selecting ground motions for liquefaction evaluation analysis of earthen levees are proposed. These guidelines were developed based on results from dynamic analyses of characteristic earthen levee cross sections using a wide range of ground motions (~1,500). The effect of a number of ground motion parameters on the dynamic response of the levees in terms of liquefaction susceptibility was studied, and the parameters that correlated best to the response were identified. For the liquefaction triggering evaluation, the mean period of the ground motion ( Tm) is best correlated to the cyclic stress ratio (CSR). Regression relationships between CSR and Tm are proposed for a series of levee types and shaking intensities.

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