May Webinars: **NEW ** Seismic Cycle Series & CIG Webinar

NEW Seismic Cycles Webinar Series
The Seismic Cycles Working Group presents this weekly seminar series in preparation for a virtual symposium this Fall on seismic cycles modeling. The weekly seminar series will stretch until July 2022. Each week, we invite two speakers to give a 30-minute talk. The seminar series kicks off on May 6, 9A-10A PDT on the topic of Physics-based foreshock and aftershock modeling - what can explain the observed rate of aftershocks and the possible origins of the Gutenberg-Richter frequency-size distribution:

  • Speaker 1: So Ozawa, University of Tokyo
    Mainshock and aftershock sequence simulations in a nonplanar fault network
    Aftershocks seem to be located along the trace of the mainshock fault; however, due to the location error, we do not know their exact location relative to the mainshock fault. Here, we hypothesize that most aftershocks occur on small subsidiary faults instead of the mainshock fault, and they are triggered by the local increase of stress due to the rough geometry of the mainshock fault. To explore this scenario, we perform 2-D earthquake sequence simulations considering a rough main fault and numerous subsidiary faults that obey the rate and state friction law. We show that many aftershocks occur at the side of the main fault, delineating the main fault trace. We also show that the roughness of the main fault decreases the concentration of aftershocks around the tip of the mainshock fault. Our numerical simulation reproduces the Omori-Utsu law for the temporal decay of aftershocks and the log-time expansion of the aftershock zone. This is one of the first earthquake sequence simulations based on the continuum mechanics framework that reproduces realistic spatiotemporal aftershock activities.

  • Speaker 2: Shiying Nie, University of Southern California - tbd

More info: [SC Webinar Series] [week 1]

Poroelastic Implementation in PyLith: Gateway to Multiphysics
Robert Walker, SUNY Buffalo
PyLith, a community, open-source code for modeling quasi-static and dynamic crustal deformation with an emphasis on earthquake faulting, has recently been updated with a flexible multiphysics implementation. We demonstrate the versatility of the multiphysics implementation by extending the code to model fully coupled continuum poromechanics.
We verify the newly incorporated physics using standard benchmarks for a porous medium saturated with a slightly compressible fluid. The benchmarks include Terzaghi’s consolidation problem for the one-dimensional case, Mandel’s problem for the two-dimensional case, and Cryer’s problem for the three-dimensional case; all three benchmarks have been added to the PyLith continuous integration test suite. We compare the closed form analytical solution for each benchmark against solutions generated by our updated code. [more info]