University of Texas at Austin

Past Event: Oden Institute Seminar

Unraveling earthquake dynamics through large-scale multi-physics simulations - (Note Different Day/Time)

Alice Gabriel, Assistant Professor, Ludwig Maximilians University (LMU) of Munich

11 – 12PM
Monday Mar 25, 2019

POB 6.304

Abstract

Earthquakes are highly non-linear multiscale problems, encapsulating the geometry and rheology of propagating shear fractures that render the Earth’s crust and emanate destructive seismic waves. Using physics-based earthquake scenarios, modern numerical methods and hardware specific optimizations sheds light on the dynamics, and severity, of earthquake behaviour. This is enabled by the open-source software SeisSol (www.seissol.org) that couples seismic wave propagation of high-order accuracy in space and time (minimal dispersion errors) with frictional fault failure, off-fault inelasticity and visco-elastic attenuation. SeisSol exploits unstructured tetrahedral meshes to account for complex geometries, e.g. high resolution topography and bathymetry, 3D subsurface structure, and complex fault networks. The achieved degree of realism and accuracy is enabled by recent computational optimizations targeting strong scalability on many-core CPUs and a ten-fold speedup owing to an efficient local time-stepping algorithm (Uphoff et al., SC’17). The potential of in-scale earthquake rupture simulations for augmenting earthquake source observations is demonstrated in two recent examples: i) The 2016 $M_w$7.8 Kaikoura, New Zealand earthquake, considered the most complex rupture observed to date and causing surface rupture of at least 21 segments of the Marlborough fault system. High resolution dynamic rupture modeling unravels the event's riddles in a physics-based manner (Ulrich et al., Nature Comm. 2019, https://rdcu.be/bqZOI); ii) A “reloaded” scenario of the 1992 $M_w$7.3 Landers earthquake (Wollherr et al., preprint https://eartharxiv.org/kh6j9/) producing high-quality synthetic ground motions of variability close to what is commonly assumed in Ground Motion Prediction Equations despite very complex rupture evolution. Lastly, I will discuss future directions for exploiting expected exascale computing infrastructure with the ExaHyPE high-performance engine for hyperbolic systems of PDEs (www.exahype.eu). Specifically, we aim to represent complex geometries with novel geometric transformations and multi-physics by diffuse interfaces on adaptive cartesian meshes, thus avoiding manual meshing. I will also touch on a recently developed dynamic source inversion approach using a bayesian framework where the posterior probability density function is sampled using the Parallel Tempering Monte Carlo algorithm. Bio Alice-Agnes Gabriel is an Assistant Professor of Geophysics at Ludwig Maximilians University (LMU) of Munich. Her research focuses on understanding the physics of earthquakes using theoretical analysis, physics-based forward models, innovative observation techniques and high-performance computing to bridge spatio-temporal scales. She interlaces earthquake dynamics with long-term deformation, seismic cycling, tsunami genesis and laboratory experiments in large-scale collaborative research projects fusing expertise from Earth science, physics and computational mathematics to study the fundamentals of earthquake physics and develop methodological innovations for seismology. She is specifically interested in simulating waves and rupture processes within arbitrarily complex geological structures to enhance classic probabilistic seismic hazard assessment and a wide range of industry applications. Her career is distinguished by first-rate earthquake scenarios realized on some of the largest supercomputers worldwide. Her research was rewarded as Best Paper of SC'17, as a Gordon Bell Prize Finalist at SC'14, with a PRACE ISC Award in 2014 and an AGU OSPA Award in 2012. Dr. Gabriel has a BSc and MSc in theoretical physics from TU Dresden, Germany, a Ph.D. in seismology from ETH Zurich, Switzerland and was a postdoctoral scholar at Ludwig Maximilians University of Munich, Germany.

Event information

Date
11 – 12PM
Monday Mar 25, 2019
Location POB 6.304
Hosted by Omar Ghattas