The Effects of 3D Heterogeneity on Regional Moment Tensor Source-Type Discrimination: Application to the Western United States
Session: Explosion Seismology Applications and Advances [Poster]
Type: Poster
Date: 4/19/2021
Presentation Time: 11:30 AM Pacific
Description:
The use of regional distance long-period, complete waveform data to determine the seismic moment tensor is now a routine and reliable approach in determining the source mechanism of natural and manmade seismicity and is used to identify or discriminate different types of seismic sources. However, seismic source characterization is dependent upon having a well-calibrated Earth model to compute the synthetic Green’s functions for the inverse problem. Although 1D Earth models are good approximations for real Earth structure to model regional-distance, long period surface waves, to extend the moment tensor inversion method to lower magnitude events and to greater distances requires higher fidelity Earth models to capture the 3D variations in subsurface material properties. Recent advancements in computational capabilities have greatly improved the performance of 3D-wavefield simulations, thus greatly reducing the computational resources needed to calculate 3D synthetic Green’s functions for full waveform inversion. Using a waveform-based 3D Earth model from adjoint tomography we investigate and quantify the improvements in seismic source characterizations by working with an existing waveform data set of explosions and earthquakes from the western United States. The details of the 3D Earth model can be found in the accompanying presentation by Rodgers et al., 2021. From this data set we calculated a catalog of 1D moment tensor solutions to establish the baseline performance in order to examine how the regional-scale waveform-based 3D model improves the waveform fits at shorter periods (<20 seconds) and at greater distances (> 300 km) relative to current methods using 1D models. To quantitatively compare 1D and 3D moment tensor solutions we explore the model’s effect on solution uncertainty in the moment tensor source-type space.
Presenting Author: Andrea Chiang
Student Presenter: No
Authors
Andrea Chiang Presenting Author Corresponding Author chiang4@llnl.gov Lawrence Livermore National Laboratory |
Arthur Rodgers rodgers7@llnl.gov Lawrence Livermore National Laboratory |
Lion Krischer lion.krischer@mondaic.com Mondaic |
Michael Afanasiev michael.afanasiev@mondaic.com Mondaic |
Christian Boehm christian.boehm@mondaic.com Mondaic |
Nathan Simmons simmons27@llnl.gov Lawrence Livermore National Laboratory |
Christina Morency morency1@llnl.gov Lawrence Livermore National Laboratory |
Claire Doody claired@berkeley.edu University of California, Berkeley |
|
The Effects of 3D Heterogeneity on Regional Moment Tensor Source-Type Discrimination: Application to the Western United States
Category
Explosion Seismology Applications and Advances