Physics-based modeling of earthquake cycles and tsunamis in strike-slip fault zones

Abdelmeguid, Mohamed Ezzeldin Elsayed Ahmed

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https://hdl.handle.net/2142/117773 Copy

Description

Title

Physics-based modeling of earthquake cycles and tsunamis in strike-slip fault zones

Author(s)

Abdelmeguid, Mohamed Ezzeldin Elsayed Ahmed

Issue Date

2022-11-27

Director of Research (if dissertation) or Advisor (if thesis)

Elbanna, Ahmed

Doctoral Committee Chair(s)

Elbanna, Ahmed

Committee Member(s)

• Geubelle, Philippe H
• Yan, Jinhui
• Rosakis, Ares J

Department of Study

Civil & Environmental Eng

Discipline

Civil Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Earthquake cycles
• Off-fault plasticity
• Bimaterial interfaces
• Tsunami generation

Abstract

Earthquakes and tsunamis have catastrophic societal implications, causing substantial humanitarian and economical damages. Consequently, understanding earthquake machinery with a potential of predictability has been the objective of multiple fields, including experimental and theoretical studies. One of the fundamental challenges associated with identifying earthquake occurrence is the data scarcity pertaining to large earthquakes. While the fingerprint of earthquakes is devastating, due to the large return periods, our seismic catalogs are still in their infancy stage, rendering any sort of probabilistic seismic hazard assessment impossible. Physics-based numerical models capable of capturing the wide range of observations associated with earthquake source processes can help amend our seismic records and provide detailed insight into the mechanics governing earthquake nucleation, propagation, and recurrence. However, as revealed by geological observations, the fault zones hosting those earthquakes are spatially complex and evolve through different time scales, thus, presenting a significant computational challenge. In this research, we focus on developing physics-based models capable of providing insight into the complex nature of the earthquake source. One of the main pillars of this thesis is introducing a computationally-efficient algorithm capable of modeling the evolutionary nature of the earthquake machinery. The proposed methodology (FEBE) presents a potential remedy to the multi-scale nature of earthquake rupture by coupling finite element models and boundary element approaches. The development of FEBE lends support to the second pillar of this thesis, which is utilizing physics-based modeling to explore the evolution of the earthquake cycle and earthquake-induced hazards such as tsunamis. Through FEBE, we simulate earthquake cycles with varying degrees of fault zone complexity. First, we show that the introduction of material heterogeneity in the form of a low-velocity fault zone alters the characteristics of the earthquake sequence, such as recurrence time, peak slip rate, and propagation distance. Secondly, we look further into the impact of bi-material interfaces on earthquake cycles and highlight enhanced seismic hazards. Thirdly, we incorporate inelastic behavior in the fault zone and demonstrate that the partitioning of deformations between the bulk and slip surface introduces seismic complexity that has been previously unrecognized. We then note inelastic strain accumulation patterns, previously identified by single earthquake simulations, can vary significantly in sequences of earthquakes due to the role of aseismic deformations. Finally, we highlight the importance of physics-based models in providing valuable insight into the nature of earthquake-induced hazards. We demonstrate, through a study of the tsunamigensis associated with strike-slip faulting, an unexpected potential for strike-slip faults to generate devastating tsunamis. A previously unrecognized hazard for coastal cities worldwide.

Graduation Semester

2022-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Mohamed Ezzeldin Elsayed Ahmed Abdelmeguid

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