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Resolving simulated sequences of earthquakes and fault interactions: implications for physics-based seismic hazard assessment

Lambert, Valère and Lapusta, Nadia (2021) Resolving simulated sequences of earthquakes and fault interactions: implications for physics-based seismic hazard assessment. . (Unpublished)

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Physics-based numerical modeling of earthquake source processes strives to predict quantities of interest for seismic hazard, such as the probability of an earthquake rupture jumping between fault segments. How to assess the predictive power of numerical models remains a topic of ongoing debate. Here, we investigate how sensitive are the outcomes of numerical simulations of sequences of earthquakes and aseismic slip to choices in numerical discretization and treatment of inertial effects, using a simplified 2-D crustal fault model with two co-planar segments separated by a creeping barrier. Our simulations demonstrate that simplifying inertial effects and using oversized cells significantly affects the resulting earthquake sequences, including the rate of two-segment ruptures. We find that a number of fault models with different properties and modeling assumptions can produce comparable frequency-magnitude statistics and static stress drops but have rates of two-segment ruptures ranging from 0 (single-segment ruptures only) to 1 (two-segment ruptures only). For sufficiently long faults, we find that long-term sequences of events can substantially differ even among simulations that are well-resolved by standard considerations. In such simulations, some outcomes, such as static stress drops, are stable among adequately-resolved simulations, whereas others, such as the rate of two-segment ruptures, can be highly sensitive to numerical procedures and physical assumptions, and hence cannot be reliably inferred. Our results emphasize the need to examine the potential dependence of simulation outcomes on the modeling procedures and resolution, particularly when assessing their predictive value for seismic hazard assessment.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Lambert, Valère0000-0002-6174-9651
Lapusta, Nadia0000-0001-6558-0323
Additional Information:The copyright holder for this preprint is the author/funder. Published Online: Fri, 9 Apr 2021. This study was supported by the National Science Foundation (grants EAR 1142183 and 1520907) and the Southern California Earthquake Center (SCEC), contribution No. 10089. SCEC is funded by NSF Cooperative Agreement EAR-1033462 and USGS Cooperative Agreement G12AC20038. Numerical simulations for this study were carried out on the High Performance Computing Center cluster of the California Institute of Technology. This study was motivated by insightful discussions within the SCEC community. Details about the fault models and numerical parameters for calculations are provided in the main and supplementary text, and Tables 1-2. Data were not used, nor created for this research.
Group:Seismological Laboratory
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
Subject Keywords:Geophysics
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Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center10089
Record Number:CaltechAUTHORS:20210421-092618302
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108779
Deposited By: Tony Diaz
Deposited On:21 Apr 2021 21:11
Last Modified:21 Apr 2021 21:11

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