Surface Deformation Related to the 2019 M_w 7.1 and 6.4 Ridgecrest Earthquakes in California from GPS, SAR Interferometry, and SAR Pixel Offsets
Abstract
We analyzed Synthetic Aperture Radar (SAR) images from Copernicus Sentinel‐1A and 1B satellites operated by the European Space Agency and the Advanced Land Observation Satellite‐2 (ALOS‐2) satellite operated by the Japan Aerospace Exploration Agency and Global Navigation Satellite System (GNSS) data from the Network of the Americas for the 4 July 2019 M_w 6.4 and 5 July (local; 6 July UTC) M_w 7.1 Ridgecrest earthquakes. We integrated geodetic measurements for the 3D vector field of coseismic surface deformation for the two events, using SAR data from Sentinel‐1 and ALOS‐2 satellites. We combined less precise large‐scale displacements from SAR images by pixel offset tracking or matching, including the along‐track component, with the more precise SAR interferometry (Interferometric Synthetic Aperture Radar [InSAR]) measurements in the radar line of sight (LoS) direction and intermediate‐precision along‐track InSAR to estimate all three components of the surface displacement for the two events together. We also estimated the coseismic deformation for the two earthquakes from time‐series processing of continuous Global Navigation Satellite System data stations in the area. InSAR coherence and coherence change maps the surface disruptions due to fault ruptures reaching the surface. Large slip in the M_w 6.4 earthquake was on a NE‐striking fault that intersects with the NW‐striking fault that was the main rupture in the M_w 7.1 earthquake. The main fault bifurcates towards the southeast ending 3 km from the Garlock Fault. The Garlock fault had triggered slip of about 20 mm in the radar LoS along a short section directly south of the main rupture. About 3 km northwest of the M_w 7.1 epicenter, the surface fault separates into two strands that form a pull‐apart with about 1 m of down‐drop. Further northwest is a wide zone of complex deformation.
Additional Information
© 2020 Seismological Society of America. Manuscript received 8 October 2019; Published online 4 March 2020. The authors thank the Interferometric Synthetic Aperture Radar (InSAR) Scientific Computing Environment (ISCE) software developers, Lijun Zhu, and Brent Minchew for writing software the authors used for their Synthetic Aperture Radar (SAR) analysis. The authors thank Eric Lindsey, an anonymous reviewer, and the associate editor for comments and suggestions to improve the article. This work contains modified Copernicus data from the Sentinel‐1A and 1B satellites provided by the European Space Agency (ESA). Original Advanced Land Observation Satellite‐2 (ALOS‐2) data and products are copyright Japan Aerospace Exploration Agency (JAXA) and provided under JAXA ALOS Research Announcements 4 and 6 (RA4 and RA6). This material is based in part on services provided by the Geodetic Facility for the Advancement of Geoscience (GAGE) Facility, operated by UNAVCO, Inc., with support from the National Science Foundation (NSF) and the National Aeronautics and Space Administration under NSF Cooperative Agreement EAR‐1724794. Part of this research was sponsored by the National Aeronautics and Space Administration (NASA) Earth Surface and Interior focus area and performed at the Jet Propulsion Laboratory (JPL), California Institute of Technology. Data and Resources: Synthetic Aperture Radar (SAR) and Global Navigation Satellite System (GNSS) processed coseismic data products presented here are available from the Advanced Rapid Imaging and Analysis (ARIA)‐share website available at https://aria-share.jpl.nasa.gov/20190704-0705-Searles_Valley_CA_EQs/SRL-Data_Mine/. The SAR and GNSS data products have also been published in the Harvard Dataverse archive under doi: 10.7910/DVN/JL9YMS. The supplemental material contains the GNSS coseismic offsets in table form as in Table S1. Generic Mapping Tools (GMT; Wessel and Smith 1998) were used to prepare figures. QGIS (QGIS Development Team, 2019) was used to select items from databases, pick the image coverage, and prepare figures. The Interferometric Synthetic Aperture Radar (InSAR) Scientific Computing Environment (ISCE) v.2 software (Rosen et al., 2012) is available as open‐source software on GitHub at https://github.com/isce-framework/isce2. The additional ISCE modules for processing Advanced Land Observation Satellite‐2 (ALOS‐2) ScanSAR interferograms (Liang and Fielding, 2017a) are available as open‐source software on GitHub at https://github.com/CunrenLiang/insarzd. ALOS‐2 modules will be incorporated into a future version of ISCE v.2 package. The vector_disp program for calculating 3D surface displacements from InSAR, SAR pixel offsets, and other data is available as open‐source on GitHub at https://github.com/bminchew/vector_disp. Original Copernicus Sentinel‐1 data are available at no charge from the Copernicus Sentinels Scientific Data Hub (https://scihub.copernicus.eu/) and is also mirrored at the National Aeronautics and Space Administration (NASA) Alaska Satellite Facility archive center (https://search.asf.alaska.edu/). Original ALOS‐2 data are available from Japan Aerospace Exploration Agency (JAXA; https://auig2.jaxa.jp/ips/home). Shuttle Radar Topography Mission (SRTM) digital elevation models are available for no charge from the NASA‐USGS Land Processes Distributed Active Archive Center (https://lpdaac.usgs.gov/). GNSS data from the Network of the Americas (formerly Plate Boundary Observatory) are available from UNAVCO (https://www.unavco.org/data/data.html). The Jet Propulsion Laboratory (JPL) GipsyX software for processing GNSS data is available with a license from https://gipsy-oasis.jpl.nasa.gov/. The USGS National Earthquake Information Center (NEIC) moment tensors and hypocenter data are available from http://earthquake.usgs.gov/. The USGS Quaternary faults database is available from https://earthquake.usgs.gov/hazards/qfaults/. Version used here was downloaded in April 2019. All websites were last accessed in February 2020. The unpublished manuscripts by W. Bertiger, E. Bar‐Sever, A. Dorsey, B. Haines, N. Harvey, D. Hemberger, and P. Willis (2019), "GipsyX/RTGx: A software set and results for operations and space research," submitted to Adv. Space Res. and D. J. Ponti, J. L. Blair, C. M. Rosa, K. Thomas, A. J. Pickering, S. Akciz, S. Angster, J.‐P. Avouac, J. Bachhuber, and S. Bacon et al. (2020), "Documentation of surface fault rupture and ground deformation features produced by the Ridgecrest M6.4 and M7.1 earthquake sequence of July 4 and 5, 2019," submitted to Seismol. Res. Lett.Attached Files
Supplemental Material - srl-2019302_supplement.docx
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Additional details
- Eprint ID
- 103038
- Resolver ID
- CaltechAUTHORS:20200506-125644583
- EAR-1724794
- NSF
- NASA/JPL/Caltech
- Created
-
2020-05-06Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Seismological Laboratory, Division of Geological and Planetary Sciences