Near-Source Ground Motions and Their Variability Derived from Dynamic Rupture Simulations Constrained by NGA-West2 GMPEs

2021 ◽  
Author(s):  
Ľubica Valentová ◽  
František Gallovič ◽  
Sébastien Hok
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Synthetic Data ◽  
Ground Motion Prediction Equations ◽  
Dynamic Rupture ◽  
Motion Modeling ◽  
Mixed Effect ◽  
Effect Model ◽  
Stress Drops ◽  
Strong Ground

ABSTRACT Empirical ground-motion prediction equations (GMPEs) lack a sufficient number of measurements at near-source distances. Seismologists strive to supplement the missing data by physics-based strong ground-motion modeling. Here, we build a database of ∼3000 dynamic rupture scenarios, assuming a vertical strike-slip fault of 36×20  km embedded in a 1D layered elastic medium and linear slip-weakening friction with heterogeneous parameters along the fault. The database is built by a Monte Carlo procedure to follow median and variability of Next Generation Attenuation-West2 Project GMPEs by Boore et al. (2014) at Joyner–Boore distances 10–80 km. The synthetic events span a magnitude range of 5.8–6.8 and have static stress drops between 5 and 40 MPa. These events are used to simulate ground motions at near-source stations within 5 km from the fault. The synthetic ground motions saturate at the near-source distances, and their variability increases at the near stations compared to the distant ones. In the synthetic database, the within-event and between-event variability are extracted for the near and distant stations employing a mixed-effect model. The within-event variability is lower than its empirical value, only weakly dependent on period, and generally larger for the near stations than for the distant ones. The between-event variability is by 1/4 lower than its empirical value at periods >1  s. We show that this can be reconciled by considering epistemic error in Mw when determining GMPEs, which is not present in the synthetic 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.

Dynamic Rupture Simulations of the 1920 Ms 8.5 Haiyuan Earthquake in China

2019 ◽  
Vol 109 (5) ◽  
pp. 2009-2020 ◽  
Author(s):  
Xiurong Xu ◽  
Zhenguo Zhang ◽  
Feng Hu ◽  
Xiaofei Chen
Keyword(s):  
Ground Motion ◽  
Intensity Distribution ◽  
Strong Ground Motion ◽  
Ground Surface ◽  
Peak Ground Velocity ◽  
The Tibetan Plateau ◽  
Dynamic Rupture ◽  
Seismogenic Fault ◽  
Maximum Displacement ◽  
Strong Ground

Abstract The Haiyuan fault is a major seismogenic fault on the northeastern edge of the Tibetan–Qinghai plateau. The 16 December 1920 Ms 8.5 Haiyuan, China, earthquake is the largest and most recent event along the eastern Haiyuan fault (the Haiyuan fault in the article). Because only a few near‐field seismic recordings are available, the rupture process remains unclear. To understand the source process and intensity distribution of the 1920 Haiyuan earthquake, we simulated the dynamic rupture and strong ground motion of said earthquake using the 3D curved‐grid finite‐difference method. Considering the differences in epicenter locations among various catalogs, we constructed two models with different source points. For each model, three versions with different fault geometries were investigated: one continuous fault model and two discontinuous fault models with different stepover widths (1.8 and 2.5 km, respectively). A dynamic rupture source model with a final slip distribution similar to that observed on the ground surface was found. The maximum displacement on the ground surface was ∼6.5  m. Based on the dynamic rupture model, we also simulated the strong ground motion and estimated the theoretical intensity distribution. The maximum value of the horizontal peak ground velocity occurs near Haiyuan County, where the intensity reaches XI. Without considering the site conditions, the intensity values in most regions, based on the dynamic scenarios, are smaller than the values from field investigation. In this work, we present physically based insights into the 1920 Haiyuan earthquake, which is important for understanding rupture processes and preventing seismic hazards on the northeastern boundary of the Tibetan plateau.

Dynamic Rupture and Ground Motion Modeling of the 2016 M6.2 Amatrice and M6.5 Norcia, Central Italy, Earthquakes Constrained by Bayesian Dynamic Source Inversion

2020 ◽  
Author(s):  
Taufiq Taufiqurrahman ◽  
Alice-Agnes Gabriel ◽  
Frantisek Gallovic ◽  
Lubica Valentova
Keyword(s):  
Ground Motion ◽  
Dynamic Models ◽  
Central Italy ◽  
Foot Wall ◽  
Source Inversion ◽  
Dynamic Rupture ◽  
Highly Efficient ◽  
Starting Point ◽  
Dynamic Source ◽  
Strong Ground

<p>The complex evolution of earthquake rupture during the 2016 Central Italy sequence and the uniquely dense seismological observations provide an opportunity to better understand the processes controlling earthquake dynamics, strong ground motion, and earthquake interaction. </p><p>We here use fault initial stress and friction conditions constrained by a novel Bayesian dynamic source inversion as a starting point for high-resolution dynamic rupture scenarios. The best-fitting forward models are chosen out of ~10<sup>6</sup> highly efficient simulations restricted to a simple planar dipping fault. Such constrained, highly heterogeneous dynamic models fit strong motion data well. Utilizing the open-source SeisSol software (www.seissol.org), we then take into account non-planar (e.g., listric) fault geometries, inelastic off-fault damage rheology, free surface effects and topography which cannot be accounted for in the highly efficient dynamic source inversion. SeisSol is based on the discontinuous Galerkin method on unstructured tetrahedral meshes optimized for modern supercomputers. </p><p>We investigate the effects of including the realistic modeling ingredients on rupture dynamics and strong ground motions up to 5 Hz. Synthetic PGV mapping reveals that specifically fault listricity decreases ground motion amplitudes by  ~50 percent in the extreme near field on the foot-wall. On the hanging-wall shaking is increased by ~150 percent as a consequence of wave-focusing effects within 10 km away from the fault. Dynamic modeling thus suggests that geometrical fault complexity is important for seismic hazard assessment adjacent to dipping faults but difficult to identify by kinematic source inversions.</p>

A Ground-Motion Logic-Tree Scheme for Regional Seismic Hazard Studies

2017 ◽  
Vol 33 (3) ◽  
pp. 837-856 ◽  
Author(s):  
Özkan Kale ◽  
Sinan Akkar
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Motion Prediction ◽  
Motion Model ◽  
Ground Motion Prediction Equations ◽  
Ground Motion Prediction ◽  
Logic Tree ◽  
Ground Motion Model ◽  
The One

We propose a methodology that can be useful to the hazard expert in building ground-motion logic trees to capture the center and range of ground-motion amplitudes. The methodology can be used to identify a logic-tree structure and weighting scheme that prevents the dominancy of a specific ground-motion model. This strategy can be useful for regional probabilistic seismic hazard since logic-trees biased by a specific ground-motion predictive model (GMPE) may cause disparities in the seismic hazard for regions represented by large number of sites with complex seismic features. The methodology first identifies a suit of candidate ground-motion prediction equations that can cover the center, body and range of estimated ground motions. The GMPE set is then used for establishing alternative logic-trees composed of different weighting schemes to identify the one(s) that would not be biased towards a particular GMPE due to its sensitivity to the weights. The proposed methodology utilizes visual and statistical tools to assess the ground motion distributions over large areas that makes it more practical for regional hazard studies.

Ground-Motion Modeling of Hayward Fault Scenario Earthquakes, Part II: Simulation of Long-Period and Broadband Ground Motions

2010 ◽  
Vol 100 (6) ◽  
pp. 2945-2977 ◽  
Author(s):  
B. T. Aagaard ◽  
R. W. Graves ◽  
A. Rodgers ◽  
T. M. Brocher ◽  
R. W. Simpson ◽  
...  
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Motion Modeling ◽  
Long Period ◽  
Scenario Earthquakes

From Source to Building Fragility: Post-event Assessment of the 2013 M7.1 Bohol Philippines Earthquake

2019 ◽  
pp. 101716EQS173M
Author(s):  
Muriel Naguit ◽  
Phil Cummins ◽  
Mark Edwards ◽  
Hadi Ghasemi ◽  
Bartolome Bautista ◽  
...  
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Source Model ◽  
Motion Prediction ◽  
Ground Motion Prediction Equations ◽  
Ground Motion Prediction ◽  
Effective Implementation ◽  
Ideal Candidate ◽  
Post Disaster ◽  
Disaster Exposure

We use ground motion simulations of the 2013 Bohol Philippines earthquake along with a new post-disaster exposure/damage database to constrain building fragility and vulnerability. The large number of damaged buildings (>70,000) and the wide spread of seismic intensities caused by this earthquake make it an ideal candidate for such a study. An extensive survey was conducted leading to a robust description of over 25,000 damaged and undamaged structures. Ground motion fields were simulated using ground motion prediction equations and stochastic modeling, and the estimated and observed values were compared. The finite source model used in the simulation was based on the analysis of aftershocks and SAR data. The ground motions were associated with the empirical database to derive fragility and vulnerability models. Results indicate that the pattern of damage is best captured in the stochastic simulation. Constraints were placed on seismic building fragility and vulnerability models, which can promote more effective implementation of construction regulations and practices.

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