Engineering Characteristics of Ground Motions Recorded in the 2019 Ridgecrest Earthquake Sequence

2020 ◽  
Vol 110 (4) ◽  
pp. 1474-1494 ◽  
Author(s):  
Sean Kamran Ahdi ◽  
Silvia Mazzoni ◽  
Tadahiro Kishida ◽  
Pengfei Wang ◽  
Chukwuebuka C. Nweke ◽  
...  
Keyword(s):  
Ground Motion ◽  
Fault Zone ◽  
Ground Motions ◽  
Response Spectra ◽  
Earthquake Sequence ◽  
Damage Potential ◽  
Ground Acceleration ◽  
Intensity Measures ◽  
Inelastic Response ◽  
Motion Models

ABSTRACT We present a database and analyze ground motions recorded during three events that occurred as part of the July 2019 Ridgecrest earthquake sequence: a moment magnitude (M) 6.5 foreshock on a left-lateral cross fault in the Salt Wells Valley fault zone, an M 5.5 foreshock in the Paxton Ranch fault zone, and the M 7.1 mainshock, also occurring in the Paxton Ranch fault zone. We collected and uniformly processed 1483 three-component recordings from an array of 824 sensors spanning 10 seismographic networks. We developed site metadata using available data and multiple models for the time-averaged shear-wave velocity in the upper 30 m (VS30) and for basin depth terms. We processed ground motions using Next Generation Attenuation (NGA) procedures and computed intensity measures including spectral acceleration at a number of oscillator periods and inelastic response spectra. We compared elastic and inelastic response spectra to seismic design spectra in building codes to evaluate the damage potential of the ground motions at spatially distributed sites. Residuals of the observed spectral accelerations relative to the NGA-West2 ground-motion models (GMMs) show good average agreement between observations and model predictions (event terms between about −0.3 and 0.5 for peak ground acceleration to 5 s). The average attenuation with distance is also well captured by the empirical NGA-West2 GMMs, although azimuthal variations in attenuation were observed that are not captured by the GMMs. An analysis considering directivity and fault-slip heterogeneity for the M 7.1 event demonstrates that the dispersion in the near-source ground-motion residuals can be reduced.

scholarly journals Characteristics of strong ground motion attenuation in the 2019 Mw 5.8 Changning earthquake, Sichuan, China

2021 ◽  
Author(s):  
J. J. Hu ◽  
H. Zhang ◽  
J. B. Zhu ◽  
G. H. Liu
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Peak Ground Velocity ◽  
Arias Intensity ◽  
Ground Acceleration ◽  
Motion Models ◽  
Ground Motion Attenuation ◽  
Short Period ◽  
Strong Ground

AbstractA moderate magnitude earthquake with Mw 5.8 occurred on June 17, 2019, in Changning County, Sichuan Province, China, causing 13 deaths, 226 injuries, and serious engineering damage. This earthquake induced heavier damage than earthquakes of similar magnitude. To explain this phenomenon in terms of ground motion characteristics, based on 58 sets of strong ground motions in this earthquake, the peak ground acceleration (PGA), peak ground velocity (PGV), acceleration response spectra (Sa), duration, and Arias intensity are analyzed. The results show that the PGA, PGV, and Sa are larger than the predicted values from some global ground motion models. The between-event residuals reveal that the source effects on the intermediate-period and long-period ground motions are stronger than those on short-period ground motions. Comparison of Arias intensity attenuation with the global models indicates that the energy of ground motions of the Changning earthquake is larger than those of earthquakes with the same magnitude.

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.

Inelastic response spectra of self-centering structures with the flag-shaped hysteretic response subjected to near-fault pulse-type ground motions

2021 ◽  
pp. 875529302110003
Author(s):  
Huihui Dong ◽  
Qiang Han ◽  
Xiuli Du ◽  
Shoushan Cheng ◽  
Haifang He
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Displacement Velocity ◽  
Hysteretic Behavior ◽  
Hysteretic Model ◽  
Inelastic Response ◽  
Inelastic Displacement ◽  
Near Fault ◽  
Pulse Type

Many studies on the inelastic response spectra have mainly focused on structures with the conventional hysteretic behavior. However, for self-centering structures with the flag-shaped (FS) hysteretic behavior, the corresponding study is limited. The primary aim of this study is to investigate the inelastic response spectra of self-centering structures with FS hysteretic behavior subjected to the near-fault pulse-type ground motion. To this end, the smooth FS hysteretic model based on Bouc–Wen model is developed, and the characteristics of pulse-type ground motions are described in detail. It is found that the general features of inelastic response spectra of the FS model are sensitive to the acceleration-, velocity-, and displacement-sensitive spectral regions of the ground motion. The inelastic displacement, velocity, acceleration, and ductility factor spectra of the FS hysteretic model for pulse-type ground motions are much larger than those for ordinary ground motions, while the residual displacement spectra under the two types of ground motions are both very small due to its self-centering capacity. Moreover, the inelastic response spectra are affected by the ground motion characteristics and structural hysteresis behavior, especially the large pulse period and peak ground velocity (PGV) significantly increase the inelastic displacement, velocity, and acceleration spectra.

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.

Source and Attenuation Properties of the 2012 Moe, Southeastern Australia, Earthquake Sequence

2021 ◽  
Author(s):  
Ryan Hoult ◽  
Trevor Allen ◽  
Elodie Borleis ◽  
Wayne Peck ◽  
Anita Amirsardari
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Earthquake Sequence ◽  
Motion Models ◽  
Southeastern Australia ◽  
Stable Continental Region ◽  
Short Period ◽  
Eastern Australia ◽  
Seismic Networks ◽  
Macroseismic Intensities

Abstract The 19 June 2012 local magnitude ML 5.4 (Mw 5.1) Moe earthquake, which occurred within the Australian stable continental region, was the largest seismic event for the state of Victoria, for more than 30 yr. Seismic networks in the southeast Australian region yielded many high-quality recordings of the moderate-magnitude earthquake mainshock and its largest aftershock (ML 4.4 and Mw 4.3) at a range of distances from the epicenter. The source and attenuation characteristics of the earthquake sequence are analyzed. Almost 15,000 felt reports were received following the mainshock, and its ground motions tripped a number of coal-fired power generators in the region amounting to the loss of, approximately, 1955 MW of generation capacity. The attenuation of macroseismic intensities is shown to mimic the attenuation shape of eastern North America (ENA) models but requires an interevent bias to reduce predicted intensities. Furthermore, instrumental ground-motion recordings are compared to ground-motion models (GMMs) considered applicable for the southeastern Australian (SEA) region. Some GMMs developed for ENA and SEA provide reasonable estimates of the recorded ground motions of spectral acceleration within epicentral distances of, approximately, 100 km. The mean Next Generation Attenuation-East GMM, recently developed for stable ENA, performs relatively poorly for the 2012 Moe earthquake sequence, particularly, for short-period accelerations. These observations will help inform future seismic hazard assessments for eastern Australia.

scholarly journals Analysis of accelerograms—Parkfield earthquake

1967 ◽  
Vol 57 (6) ◽  
pp. 1193-1220 ◽  
Author(s):  
G. W. Housner ◽  
M. D. Trifunac
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Horizontal Displacement ◽  
Ground Acceleration ◽  
Directional Characteristic ◽  
Maximum Acceleration ◽  
Small Magnitude ◽  
Near Fault ◽  
Parkfield Earthquake

Abstract Integrated velocities and displacements show that near the fault at Cholame the surface motion exhibited a transient horizontal displacement pulse of approximately ten inches amplitude and one and one-half seconds duration, normal to the fault. Although 50 per cent of g ground acceleration was recorded at the fault, the ground motion attenuated rapidly with distance and at ten miles from the fault the maximum acceleration was reduced to one-tenth of its near-fault value. The ground motion also changed its character with distance, losing its pulse-like directional characteristic and becoming isotropic. Computed response spectra are presented and the large spectrum ordinates for this shock of relatively small magnitude and moderate destructiveness indicate that in an engineering sense the Parkfield ground motion is in a different class from such large destructive ground motions as El Centro 1940, Tehachapi 1952, and Olympia 1949.

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 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 Case Study of a Heavily Damaged Building during the 2016 MW 7.8 Ecuador Earthquake: Directionality Effects in Seismic Actions and Damage Assessment

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 74
Author(s):  
Luis A. Pinzón ◽  
Luis G. Pujades ◽  
Irving Medranda ◽  
Rodrigo E. Alva
Keyword(s):  
Damage Assessment ◽  
Strong Motion ◽  
Response Spectra ◽  
Seismic Action ◽  
Damage State ◽  
Ground Acceleration ◽  
Intensity Measures ◽  
Capacity Curves ◽  
Building Orientation

In this work, the directionality effects during the MW 7.8 earthquake, which occurred in Muisne (Ecuador) on 16 April 2016, were analyzed under two perspectives. The first one deals with the influence of these effects on seismic intensity measures (IMs), while the second refers to the assessment of the expected damage of a specific building located in Manta city, Ecuador, as a function of its azimuthal orientation. The records of strong motion in 21 accelerometric stations were used to analyze directionality in seismic actions. At the closest station to the epicenter (RRup = 20 km), the peak ground acceleration was 1380 cm/s2 (EW component of the APED station). A detailed study of the response spectra ratifies the importance of directionality and confirms the need to consider these effects in seismic hazard studies. Differences between IMs values that consider the directionality and those obtained from the as-recorded accelerograms are significant and they agree with studies carried out in other regions. Concerning the variation of the expected damage with respect to the building orientation, a reinforced concrete building, which was seriously affected by the earthquake, was taken as a case study. For this analysis, the accelerograms recorded at a nearby station and detailed structural documentation were used. The ETABS software was used for the structural analysis. Modal and pushover analyses were performed, obtaining capacity curves and capacity spectra in the two main axes of the building. Two advanced methods for damage assessment were used to obtain fragility and mean damage state curves. The performance points were obtained through the linear equivalent approximation. This allows estimation and analysis of the expected mean damage state and the probability of complete damage as functions of the building orientation. Results show that the actual probability of complete damage is close to 60%. This fact is mainly due to the greater severity of the seismic action in one of the two main axes of the building. The results are in accordance with the damage produced by the earthquake in the building and confirm the need to consider the directionality effects in damage and seismic risk assessments.

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