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Nadia Lapusta
Mechanical Engineering and Geophysics
California Institute of Technology Earthquakes Dynamic Frictional Cracks: Modeling and Simulations Abstract Earthquakes occur as dynamic shear ruptures (or frictional cracks) on faults in the Earth’s crust. In earthquake studies, the most important practical problems are the assessment of earthquake hazard and possibility of earthquake prediction. However, 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? 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. While most 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 nucleation of frictional instability, modes of dynamic rupture propagation, and strong but brittle interface behavior. Biosketch Nadia Lapusta was born in Ukraine. She graduated with highest honors from the Department of Mechanics and Mathematics at Kiev State University (Ukraine) in 1994. Her education continued in the Division of Engineering and Applied Sciences at Harvard University (USA), where she got her Ph.D. in Engineering Sciences in 2001 and continued as a Postdoctoral Fellow. She received 2002 Nicholas Metropolis Award for Outstanding Doctoral Thesis Work in Computational Physics. Since 2002, Nadia Lapusta is an Assistant Professor of Mechanical Engineering and Geophysics at the California Institute of Technology. Her research interests are in fracture and frictional processes, mechanics and physics of earthquakes, and computational mechanics.Friday, April 29, 2005
Bourns Hall A265
3:10 p.m.-4:00 p.m.
(Refreshments will be served at 3:00 p.m.) |
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