The Impact of the Three-Dimensional Structure of a Subduction Zone on Time-Dependent Crustal Deformation Measured by HR-GNSS
Description:
Accurately modeling coseismic time-dependent crustal deformation as observed on high-rate Global Navigation Satellite System (HR-GNSS) lends insight into earthquake source processes, as well as improves local earthquake and tsunami warning algorithms. Currently, time-dependent crustal deformation modeling relies most frequently on simplified 1D radially symmetric Earth models. However, for shallow subduction zone earthquakes, even low-frequency shaking is likely affected by the many strongly heterogeneous structures such as the wedge, the slab, and the overlying crustal structure. We demonstrate that including such a 3D structure in a subduction zone improves the estimation of key features of coseismic HR-GNSS time series, such as the peak ground displacement (PGD), the time it takes to reach the PGD (tPGD), static displacements, and cross correlation values. We computed 0.25 and 0.5 Hz 1D and 3D synthetic waveforms at HR-GNSS stations for four M7.3+ earthquakes in Japan using MudPy and SW4, respectively. From these synthetics, we computed intensity-measure residuals between the synthetic and observed GNSS waveforms. Comparing 1D and 3D residuals, we observed that the 3D simulations show improved fits to the PGD and tPGD in the observed waveforms than the 1D simulations. Our results also show that the reduction of the PGD residuals in the 3D simulations is a combined effect of both shallow and deep 3D structures; hence incorporating only the upper 30 km 3D structure will still improve the fit to the observed PGD values. Our results demonstrate that 3D simulations significantly improve models of GNSS waveform characteristics and will help understand the underlying processes and improve the warning of tsunami earthquakes.
Session: Future Directions in Physics-based Ground-motion Modeling in Preparation for the Fall 2023 Meeting [Poster]
Type: Poster
Date: 4/18/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Valerie J. Sahakian
Student Presenter: No
Invited Presentation:
Authors
Oluwaseun Fadugba Corresponding Author ofadugba@uoregon.edu University of Oregon |
Valerie Sahakian Presenting Author vjs@uoregon.edu University of Oregon |
Diego Melgar dmelgarm@uoregon.edu University of Oregon |
Arthur Rodgers rodgers7@llnl.gov Lawrence Livermore National Laboratory |
Roey Shimony rshimony@uoregon.edu University of Oregon |
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The Impact of the Three-Dimensional Structure of a Subduction Zone on Time-Dependent Crustal Deformation Measured by HR-GNSS
Category
Future Directions in Physics-based Ground-motion Modeling in Preparation for the Fall 2023 Meeting