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Fault Zone Imaging with Distributed Acoustic Sensing: Body-to-Surface Wave Scattering

Atterholt, James and Zhan, Zhongwen and Yang, Yan (2022) Fault Zone Imaging with Distributed Acoustic Sensing: Body-to-Surface Wave Scattering. . (Unpublished) https://resolver.caltech.edu/CaltechAUTHORS:20220711-347646000

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Abstract

Fault zone structures at many scales largely dictate earthquake ruptures and are controlled by the geologic setting and slip history. Characterizations of these structures at diverse scales inform better understandings of earthquake hazards and earthquake phenomenology. However, characterizing fault zones at sub-kilometer scales has historically been challenging, and these challenges are exacerbated in urban areas, where locating and characterizing faults is critical for hazard assessment. We present a new procedure for characterizing fault zones at sub-kilometer scales using distributed acoustic sensing (DAS). This technique involves the backprojection of the DAS-measured scattered wavefield generated by natural earthquakes. This framework provides a measure of the strength of scattering along a DAS array and thus constrains the positions and properties of local scatterers. The high spatial sampling of DAS arrays makes possible the resolution of these scatterers at the scale of tens of meters over distances of kilometers. We test this methodology using a DAS array in Ridgecrest, CA which recorded much of the 2019 M_w7.1 Ridgecrest earthquake aftershock sequence. We show that peaks in scattering along the DAS array are spatially correlated with mapped faults in the region and that the strength of scattering is frequency-dependent. We present a model of these scatterers as shallow, low-velocity zones that is consistent with how we may expect faults to perturb the local velocity structure. We show that the fault zone geometry can be constrained by comparing our observations with synthetic tests.


Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription
https://doi.org/10.1002/essoar.10511838.1DOIDiscussion Paper
https://doi.org/10.22002/D1.20038DOIData
ORCID:
AuthorORCID
Atterholt, James0000-0003-1603-5518
Zhan, Zhongwen0000-0002-5586-2607
Yang, Yan0000-0002-6105-2918
Additional Information:This study was made possible by the funding provided by the National Science Foundation (NSF) through the Faculty Early Career Development (CAREER) award number 1848106 and Graduate Research Fellowships Program (GRFP) number DGE-1745301. Additional funding was provided by the Braun Trust and the United States Geological Survey (USGS) Earthquake Hazards Program (EHP) award number G22AP00067. We would also like to thank the California Broadband Cooperative for fiber access for the Distributed Acoustic Sensing array used in this experiment. Open Research. The data used in this study are available online (https://doi.org/10.22002/D1.20038) as 30-second record sections that include the initial onset of the earthquake wavefield for the 50 high signal-to-noise ratio aftershocks recorded by the distributed acoustic sensing (DAS) array in Ridgecrest, CA referenced in this study. The simulations performed for this study were done using the software Salvus, (Afanasiev et al., 2019), available at https://mondaic.com/. Figure 1 was made using The Generic Mapping Tools (GMT), version 6 (Wessel et al., 2019), available at https://www.generic-mapping-tools.org/.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSF1848106
NSF Graduate Research FellowshipDGE-1745301
USGSG22AP00067
DOI:10.1002/essoar.10511838.1
Record Number:CaltechAUTHORS:20220711-347646000
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20220711-347646000
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115451
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:12 Jul 2022 14:39
Last Modified:12 Jul 2022 14:39

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