Modeling and Simulations of Earthquake Phenomena

DR. NADIA LAPUSTA, CalTechIn earthquake studies, the most important practical problems are the assessment of earthquake hazard and possibility of earthquake prediction. To address these issues in a satisfactory manner, detailed understanding of physics and mechanics of earthquakes is needed.How do earthquakes nucleate and arrest? What are the appropriate descriptions and parameters of fault friction during both quasi-static and dynamic deformation? How do thermal effects - such as flash heating, pore-fluid pressurization, and melting - influence dynamic rupture propagation? What is the stress state on faults and the surrounding crust? Such fundamental questions still evade understanding or consensus. Our studies are directed towards answering these questions by formulating earthquake models with constitutive laws motivated by experimental observations and physically-based theories of how fault materials respond. The goal is to simulate the response of those models in terms of spontaneous sequences of earthquakes and to find the relevant models by comparing simulated features of individual events and event sequences with observations.While most earthquake modelers consider dynamic rupture propagation in a single earthquake, we have been developing a methodology that allows us to simulate spontaneous sequences of earthquakes while fully resolving all stages of each model earthquake: quasi-static accelerating slip during the nucleation process, the resulting inertially-controlled rupture, post-seismic deformation, and ongoing slippage throughout the loading period in creeping fault regions. The resulting simulations are very challenging because of the wide range of temporal and spatial scales involved.We will present our modeling efforts and results on features of the shear rupture sequences, the process of the instability nucleation, modes of dynamic rupture propagation, and strong but brittle interface behavior.

Location: Kaprielian Hall (KAP) - -203

Audiences: Everyone Is Invited

Contact: Masako Okamoto