SCEC Award Number 18226 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Fault Roughness, Geometry and Kinematics of the Palos Verdes Fault
Investigator(s)
Name Organization
Emily Brodsky University of California, Santa Cruz
Other Participants Joel Edwards
SCEC Priorities 2d, 3a, 3e SCEC Groups FARM, Seismology, Geology
Report Due Date 03/15/2019 Date Report Submitted 04/28/2019
Project Abstract
 Exhumed faults are rough, often exhibiting topographic corrugations oriented in the direction of slip; such features are fundamental to mechanical processes that drive earthquakes and fault evolution. However, in situ observations at depth of such features remains limited. Furthermore, how slip is partitioned and deformation is distributed across faults at depth is also limited, again due to a lack of in situ observations. Here we begin to constrain the long wavelength 3D roughness, geometry and mode of deformation along the Palos Verdes Fault offshore Los Angeles utilizing two legacy 3D seismic reflection datasets. In this first year of the project, the data was processed in OpenDetect, faults were picked in the seismogram and a neural net algorithm was deployed to interpolate the surface. This work was performed by UC Santa Cruz graduate student Travis Alongi in collaboration with Danny Brothers and Jared Kluesner of the USGS.
Intellectual Merit The work is providing a three dimensional image of a fault zone including the damage zone. The connection between fault geometry and damage is a major focus of SCEC as the collaboration moves beyond elasticity. Utilizing modern machine-learning aided mapping methods to obtain this observational data is essential to developing and validating damage zone models.
Broader Impacts The work is establishing kinematic indicators on a poorly mapped and potentially hazardous fault zone directly outside the Port of Los Angeles. The offshore environment forms a conspicuous gap in our knowledge of the fault system and its associated hazard. In addition, we are performing a preliminary assessment of the potential for induced seismicity in federal waters offshore California.
Exemplary Figure Figure 3. Preliminary map of strands of the Palos Verdes Fault. Fault surfaces are mapped by a neural network trained on hand picks. Note the multiple strands visible and geometry at depth that can be now compared to the damage zone features.