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PhD Final Defense for Mohamed Abdelmeguid

Event Type
Civil and Environmental Engineering
Newmark-Quade Conference Room, NCEB
wifi event
Oct 5, 2022   12:00 pm  
Joan Christian

Physics-Based Modeling of Earthquake Cycles and Tsunamis in Strike-slip Fault Zones
Advisor: Professor Ahmed Elbanna

Earthquakes and tsunamis have catastrophic societal implications, causing substantial
humanitarian and economical damages. Consequently, understanding earthquake machinery with
the 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. Physicsbased
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
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.

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