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High-Resolution Fault Zone Imaging With Distributed Acoustic Sensing

Description: 

Multi-scale fault zone structure may largely control the behavior of earthquake ruptures and encode the long-term slip history of the fault. Detailed images of subsurface fault zone structure fill an observational gap between surface mapping and low frequency tomography studies. These images are best illuminated using multiple types of complementary observations recorded by dense instrumentation. Distributed acoustic sensing (DAS), an emergent technology that transforms fiber optic cables into dense arrays of strainmeters, yields high-density and long-duration seismic deployments that can help fill this observational gap at relatively low cost and effort. We illustrate this potential by using a DAS array that extends from Ridgecrest, CA to Barstow, CA to image the Garlock Fault Zone, a major strike-slip fault zone in the Eastern California Shear Zone. The versatility of DAS allows us to employ a multifaceted approach to imaging this fault zone that includes an active source experiment, ambient noise tomography, and travel-time anomalies from earthquakes. These approaches each provide unique constraints that together yield a highly detailed picture of the fault zone’s lateral complexity and depth-dependent structure. We observe an asymmetric fault zone with large across-fault differences and a highly heterogeneous shallow structure that simplifies with depth.

Session: Above the Seismogenic Zone: Fault Damage and Healing in the Shallow Crust

Type: Oral

Date: 4/19/2023

Presentation Time: 05:00 PM (local time)

Presenting Author: James Atterholt

Student Presenter: Yes

Invited Presentation: Yes

Authors