SPEAKER : Brittany Erickson, Geology Division, San Diego State University,
TITLE: Stable, High Order Accurate Adaptive Methods for Earthquake Cycles on Faults Crossing a Sedimentary Basin
ABSTRACT: Earthquakes are characterized by properties that evolve over a wide range of scales in both space and time which introduce difficulties when attempting to model these features in one computational method. I will discuss two techniques for modeling the full earthquake cycle where extremely long interseismic periods are interspersed with abrupt, short periods of earthquake rupture. Both methods employ high-order accurate finite difference operators satisfying a summation-by-parts (SBP) rule, with weak enforcement of boundary conditions which allows us to derive a provably stable discretization. We apply these methods to understand how sedimentary basins, similar to those found in Southern California, affect the earthquake cycle. In a homogeneous half-space, earthquakes rupturing the full seismogenic depth occur periodically. Event sequences are more complex in basin models, with one or several sub-basin events confined to the lower section of the fault followed by a
much larger, surface-rupturing event that breaks through the basin. This phenomenology emerges only for sufficiently compliant and deep basins but might help explain discrepancies between geodetic and geologic estimates of recurrence intervals on faults passing through basins, such as the San Jacinto and San Andreas faults. This talk is aimed for a broad audience and should be accessible to students with backgrounds in either applied mathematics or Earth science.