← Back to Sessions

3D 0-5 Hz Wave Propagation Simulations of the 2014 Mw5.1 La Habra Earthquake With Small-Scale Heterogeneities, Q(f) and Topography

Session: Physics-Based Earthquake Rupture Modeling and Strong Motion Simulations [Poster]

Type: Poster

Date: 4/22/2021

Presentation Time: 03:45 PM Pacific

Description: 

We perform a suite of 0-5 Hz deterministic simulations of the 2014 Mw 5.1 La Habra, CA, earthquake, with the parallel AWP-ODC-GPU code in a mesh from the Southern California Earthquake Center Community Velocity Model CVM-S4.26-M01. The finite-fault source is obtained from the Graves and Pitarka kinematic rupture generator, with statistics constrained by dynamic rough fault simulations. We include statistical distributions of small-scale crustal heterogeneities (SSHs) with an anisotropic von Karman autocorrelation to represent the effects of realistic velocity and density perturbations. In addition, frequency-dependent attenuation Q(f) and surface topography using a curvilinear grid are included in our simulations. We also explored the effects of different values of the minimum Vs in our model (200 m/s versus 500 m/s). The synthetics are compared to strong motion data at 259 sites in our model domain.

Our results show that, as expected, the effects of topography, SSHs and Q(f) become increasingly important as frequencies increase toward 5 Hz. We find that SSHs, topography, and Q(f) all contribute significantly to the synthetic ground motion by increasing values of duration-dependent metrics (i.e., cumulative energy); SSHs and topography generally reduce and Q(f) with power law exponents less than one decrease the high-frequency ground shaking amplitude. The lower minimum Vs in the mesh can locally increase the PGV by as much as 40%, but generally represents a second-order effect. We find that the CVM includes unrealistically high velocities at rock sites, where superimposing data-constrained Vs30 values produces larger ground shaking and improves the prediction of PGVs. At most stations, the best fit is obtained by including topography, SSHs and Q(f) in the simulations, indicating that these complexities need to be included in ground motion modeling for frequencies as high as 5 Hz.

Presenting Author: Zhifeng Hu

Student Presenter: Yes

Authors