Comparison of Ground Motions from Hybrid Simulations to NGA Prediction Equations

2011 ◽  
Vol 27 (2) ◽  
pp. 331-350 ◽  
Author(s):  
Lisa M. Star ◽  
Jonathan P. Stewart ◽  
Robert W. Graves
Keyword(s):  
Ground Motions ◽  
Rupture Directivity ◽  
Ground Motion Prediction Equations ◽  
Fault Rupture ◽  
Prediction Equations ◽  
San Andreas ◽  
Blind Thrust ◽  
Static Stress Drop ◽  
Basin Response ◽  
Directivity Effects

We compare simulated motions for a Mw 7.8 rupture scenario on the San Andreas Fault known as the ShakeOut event, two permutations with different hypocenter locations, and a Mw 7.15 Puente Hills blind thrust scenario, to median and dispersion predictions from empirical NGA ground motion prediction equations. We find the simulated motions attenuate faster with distance than is predicted by the NGA models for periods less than about 5.0 s After removing this distance attenuation bias, the average residuals of the simulated events (i.e., event terms) are generally within the scatter of empirical event terms, although the ShakeOut simulation appears to be a high static stress drop event. The intra-event dispersion in the simulations is lower than NGA values at short periods and abruptly increases at 1.0 s due to different simulation procedures at short and long periods. The simulated motions have a depth-dependent basin response similar to the NGA models, and also show complex effects in which stronger basin response occurs when the fault rupture transmits energy into a basin at low angle, which is not predicted by the NGA models. Rupture directivity effects are found to scale with the isochrone parameter.

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 Seismic hazard assessment of Tehran, Iran with emphasis on near-fault rupture directivity effects

2018 ◽  
Vol 31 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Ehsan Bazarchi ◽  
◽  
Reza Saberi ◽  
Majid Alinejad ◽  
◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Rupture Directivity ◽  
Fault Rupture ◽  
Near Fault ◽  
Directivity Effects

Ground Motions prediction Equations from a stochastic simulation approach for in-slab intermediate-depth earthquakes along the Hellenic subduction zone

2020 ◽  
Author(s):  
Harris Kkallas ◽  
Costas Papazachos ◽  
Dominikos Vamvakaris
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Motion Prediction ◽  
Ground Motion Prediction Equations ◽  
Prediction Equations ◽  
Ground Motion Prediction ◽  
Large Magnitude ◽  
Intermediate Depth ◽  
Back Arc

<p>We have used a stochastic approach to simulate a large number of scenarios for in-slab intermediate-depth earthquakes in the southern Aegean Sea Hellenic subduction region, by applying an extended-source model using the EXSIM code. A large database of synthetic ground motion recordings for events with magnitudes in the range <strong>M</strong>6.0-8.5 has been compiled, covering the whole southern Aegean Benioff zone. For the stochastic simulations, we followed the approach developed in our previous works (Kkallas et al., 2018a,b), where we used the anelastic attenuation from the GMPEs modeling developed by Skarlatoudis et al. (2013) to constrain the different attenuation patterns and properties for the back-arc and fore-arc area. Simulation model parameters, such as stress parameters and attenuation parameters were also adopted from previous works, while for fault parameters we adopted the typical average focal mechanisms proposed by Papazachos et al. (2000), in agreement with the regional subduction tectonics. Estimates of expected ground motion measurements (PGA and PGV values) at different distances from different earthquakes have been employed to generate hybrid Ground-Motion Prediction Equations (GMPE). More specifically, we attempt to modify the existing Ground-Motion Prediction Equations (GMPE) from Skarlatoudis et al. (2013) for intermediate-depth earthquakes along the Hellenic Arc for large magnitude events (<strong>M</strong>>6.5), so that they can be efficiently used for Seismic Hazard assessment, as the original strong-motion dataset used for their development was lacking data in this magnitude range. Peak ground accelerations and velocities predicted by the EXSIM code are generally in very good agreement with the available GMPE results for magnitudes less than <strong>M</strong>7. However, significantly lower ground motions than those predicted by the GMPEs are predicted for large-magnitude events (<strong>M</strong>>7). Using the previous results, we propose a magnitude-dependent correction for the GMPE results both back-arc and along-arc ground motions. Moreover, we demonstrate how the final earthquake ground motion scenarios, as well as the modified GMPEs affect both deterministic and probabilistic seismic hazard analysis. This work has been partly supported by the HELPOS (MIS 5002697) project.</p>

Duration Characteristics of Ground Motion Based on Wenchuan Earthquake

2011 ◽  
Vol 368-373 ◽  
pp. 1231-1234
Author(s):  
Shu Nan Lu ◽  
Chang Hai Zhai ◽  
Li Li Xie
Keyword(s):  
Wenchuan Earthquake ◽  
Ground Motion ◽  
Ground Motions ◽  
Hanging Wall ◽  
Free Field ◽  
Foot Wall ◽  
Fault Rupture ◽  
Fault Surface ◽  
Directivity Effects ◽  
Rupture Distance

Records from 56 stations on free-field within 150km to causative fault surface are used as database during the Mw7.9 Wenchuan earthquake in china. According to this study, the duration of ground motion is strongly affected by rupture distance, site conditions, fault rupture directory and thrust of hanging wall. Duration is obtained based on the time between 10 and 80 per cent of Arias intensity. A simple attenuation relation in terms of rupture distance is proposed and compared with some available predictions. The durations of tri-component ground motions on hanging wall are smaller than those on the foot wall in the same range of rupture distance. Durations of ground motions close to rupture fault resulting from directivity effects are significantly different between the forward and backward direction, and this difference reaches nearly 2 times on average.

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