The Palos Verdes Fault Damage Zone From the Seafloor to the Basement: Revealed Using Multi-Resolution Controlled Source Seismic Reflection Datasets
Description:
The distribution and intensity of fault damage zones provide insight into the inelastic response of Earth to strain. Presently, measures of the in-situ distribution of faulting at depth remain limited. Here, we identify and analyze the fault damage zone of the San Pedro Bay segment (~20 km) of the Palos Verdes Fault offshore southern California using: two legacy controlled source (low frequency) 3D seismic reflection volumes, recently collected high resolution sparker (high frequency) multichannel seismic (MCS) lines, and existing multibeam bathymetry surveys. We apply a novel algorithm to identify discontinuities in the seismic data that are attributed to faults and fractures. Using datasets collected with differing source spectra and acquisition parameters allows for the systematic analysis of the damage zone from the shallow subsurface to the basement (0 - 2 km below seafloor). The results show that damage through fracturing is concentrated around mapped faults and decreases with distance from the fault. Analysis of the 3D seismic datasets (depths ~450 - 2 km) reveal that the along-strike averaged (~ 20 km) damage zone decays exponentially with distance and extends to ~ 2 km from the central fault strand. When examining the damage zone at a shorter along-strike (4.5 km) distance in the 3D volumes or in 2D MCS cross-sections, several discrete strands are resolvable. We find that peak 2D MCS fracturing (from the seafloor to 400 meters below) correlates with a fault scarp observable in the bathymetry suggesting that this technique may be useful in determining the dominant or most recently active fault strand.
Session: Above the Seismogenic Zone: Fault Damage and Healing in the Shallow Crust [Poster]
Type: Poster
Date: 4/19/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Travis Alongi
Student Presenter: Yes
Invited Presentation:
Authors
Travis Alongi Presenting Author Corresponding Author talongi@ucsc.edu University of California, Santa Cruz |
Emily Brodsky brodsky@ucsc.edu University of California, Santa Cruz |
Jared Kluesner jkluesner@usgs.gov U.S. Geological Survey |
Daniel Brothers dbrothers@usgs.gov U.S. Geological Survey |
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The Palos Verdes Fault Damage Zone From the Seafloor to the Basement: Revealed Using Multi-Resolution Controlled Source Seismic Reflection Datasets
Category
Above the Seismogenic Zone: Fault Damage and Healing in the Shallow Crust