← Back to Sessions

The Relation of Fault Geometry to High-Frequency Radiation: Insights from the 2019 Ridgecrest Sequence

Session: Exploring Rupture Dynamics and Seismic Wave Propagation Along Complex Fault Systems [Poster]

Type: Poster

Date: 4/19/2021

Presentation Time: 03:45 PM Pacific

Description: 

The 2019 Ridgecrest earthquake sequence illuminated a large network of previously unmapped cross-cutting structures in the eastern California shear zone. Preliminary observations of regional stress drops display along-strike variability possibly related to local heterogeneities in fault geometry, which are delineated at high resolution by the density of recorded events. Coseismic damage in the immature fault zone may have contributed further temporal variation to this spatial variability, due to structural collisions or crack opening. In this study, we investigate the possible link between variations in fault geometry and spacing and the observed seismic spectrum. Existing measures of fault complexity, such as RMS roughness, are generally limited to a single fault strand and thus cannot describe interactions between cross-cutting faults. Revisiting the 20-year Ridgecrest stress drop catalogue of Trugman (2020), we investigate several novel ways to quantify fault network density, based on the geometry and relative orientations of mapped fault traces. We proceed to draw spatiotemporal correlations between observed stress drops and fault spacing. We search for characteristic frequencies at which the high-frequency seismic spectrum may be enriched due to fault geometry, which may affect the observed corner frequency. The relation of correlation frequency to spatial variations in fault orientation and spacing can constrain physical processes that contribute to the high-frequency seismic spectrum. This in turn has the potential to improve regional hazard characterization and ground motion prediction based off of fault maps.

Presenting Author: Shanna Chu

Student Presenter: No

Authors