Physics-Based Broadband Ground Motion Simulations of M6.5 Scenario Earthquakes in Central and Eastern US, Including Surface Topography: Ground Motion Variability Related to Earthquake Rupture Characteristics
Description:
We are developing a validated and computationally efficient simulation capability that can provide representative synthetic ground motions from crustal earthquakes in the Central and Eastern US, using high performance computing. The main objective is to provide constrains to refinements of existing ergodic Ground Motion Models (GMMs), for large magnitude earthquakes and near-fault distances, for which these models are less reliable. We used physics-based broadband (0-5Hz) ground motion simulations to estimate the ground motion amplitude and within event and between-event variabilities associated with fault rupture characteristics. First, as part of a strategy for selecting a reginal velocity model and validation of our rupture modeling technique, we simulated ground motion from the Mw5.0 2016 Cushing and Mw5.8 2016 Pawnee OK earthquakes. The successful simulations of both earthquakes demonstrated the reliability of our deterministic simulation approach while emphasizing the importance of including small-scale variability in the regional velocity model needed to reproduce the observed high-frequency wave scattering effects. Additional validation analysis, based on comparisons with GMMs for CEUS region and for a Mw6.5 earthquake, resulted in a very good match between the simulations and GMMs predictions.
Our initial investigation of within-event and between-event ground motion variabilities for M6.5 scenario earthquakes on a strike-slip fault, suggests that they are strongly related to spatial slip and slip rate variations, rupture velocity, rupture area and rupture initiation location. We found that the ground motion variability observed at near-fault distances (< 5 km) also persists at longer distances. Regardless of the rupture scenario, the simulated ground motion tends to fully saturate at short distances and for all periods. Analysis of effects of rupture initiation location suggest that PGV and SA can be quite variable due to rupture directivity effects. Such effects are stronger at periods longer than 1s.
Session: Understanding and Modeling the Uncertainties in Earthquake Ground Motions
Type: Oral
Date: 4/20/2023
Presentation Time: 10:45 AM (local time)
Presenting Author: Arben Pitarka
Student Presenter: No
Invited Presentation:
Authors
Arben Pitarka Presenting Author Corresponding Author pitarka1@llnl.gov Lawrence Livermore National Laboratory |
Arthur Rodgers rodgers7@llnl.gov Lawrence Livermore National Laboratory |
Ana Aguiar aguiarmoya1@llnl.gov Lawrence Livermore National Laboratory |
Vladimir Graizer vladimir.graizer@nrc.gov Nuclear Regulatory Commission |
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Physics-Based Broadband Ground Motion Simulations of M6.5 Scenario Earthquakes in Central and Eastern US, Including Surface Topography: Ground Motion Variability Related to Earthquake Rupture Characteristics
Category
Understanding and Modeling the Uncertainties in Earthquake Ground Motions