SCEC Award Number 19213 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Using 3D seismic data to study the offshore damage zones, kinematics and earthquakes in the Palos Verdes Fault region
Investigator(s)
Name Organization
Emily Brodsky University of California, Santa Cruz
Other Participants Daniel Brothers, Jared Kluesner (unfunded USGS collaborators)
Travis Alongi (Graduate Student)
SCEC Priorities 2d, 3a, 3e SCEC Groups FARM, Geology, SAFS
Report Due Date 04/30/2020 Date Report Submitted 05/30/2020
Project Abstract
 Damage zones can observationally link earthquake physics to mechanics beyond elasticity. The extent of distributed damage affects an earthquake’s propagation, its associated strong motion and perhaps even the distribution of seismicity around the fault. However, 3D observations of damage remain limited. Here we constrained damage zones offshore California using existing 3D seismic reflection datasets. Our preliminary results from the Palo Verde Fault zone show a several hundred meter wide damage zone that decays systematically away from the main strand and increases in width with depth. This work will is performed by UC Santa Cruz graduate student Travis Alongi in collaboration with Danny Brothers and Jared Kluesner of the USGS.
Intellectual Merit This work uses previously untapped active source data to address a major questions of fault physics: how does fault zone damage vary with depth, lithology and stress state. The use of modern data processing methods makes accessing the 3D damage zone possible for the first time.
Broader Impacts This grant has supported graduate student Travis Alongi. It has also supported a new collaboration between the USGS Coastal group and the UC Santa Cruz. This part of the USGS has not previously been involved in SCEC activities, despite its active work offshore California.
Exemplary Figure Figure 2. Perspective view of Thinned Fault Likelihood attribute results in high confidence ranges (0.75 - 1.00) along the Palos Verdes fault zone. The rainbow color-map ranges from red to violet, where violet is greatest probability of a fault. The attribute is projected on an strike-perpendicular line and an interpreted and interpolated horizon. Note the variable width of the damage zone along strike.