Ground Motion Characteristics of Subshear and Supershear Ruptures in the Presence of Sediment Layers

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Authors

Mohamed Abdelmeguid, Ahmed Elbanna, Ares J. Rosakis

Abstract

We investigate the impact of sediment layers on ground motion characteristics during subshear and supershear rupture growth. Our findings suggest that sediment layers may lead to local supershear propagation, affecting ground motion, especially in the fault parallel (FP) direction. In contrast to homogeneous material models, we find that in the presence of sediment layers, a larger fault normal (FN) compared to fault parallel (FP) particle velocity jump, reflects shear propagation at depth but does not rule out shallow supershear propagation. Conversely, a large fault parallel (FP) compared to fault normal (FN) particle velocity jump indicates supershear propagation at depth. In the presence of a shallow layer, we also uncover a non-monotonic behavior in the sediment’s influence on supershear transition and ground motion characteristics. During supershear propagation at depth we observe that sediment layers contribute to enhancing FP velocity pulses while minimally affecting the FN component. Furthermore, in the limit of global supershear propagation we identify local supersonic propagation within the sediment layers that significantly alters the velocity field around the rupture tip as observed on the free surface, creating both dilatational and shear Mach cones. In all our models with sediments, we also find a significant enhancement in the fault vertical component of ground velocity. This could have particular implications for hazard assessments, such as in applications related to linear infrastructure, or a higher propensity to tsunami wave generation. Our research unravels the importance of considering heterogeneous subsurface material distribution in our physical models as they can have drastic implications on earthquake source physics.

DOI

https://doi.org/10.31223/X5QD83

Subjects

Engineering, Physical Sciences and Mathematics

Keywords

Supershear rupture, ground motion, sediment layers, dynamic rupture modeling

Dates

Published: 2024-07-19 10:19

Last Updated: 2024-07-19 16:29

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
The software used to conduct the dynamic rupture model is open access and can be obtained at \url{https://github.com/wqseis/drdg3d}.