Spatiotemporal variations of stress and strain in the crust near 2019 Ridgecrest Sequence Earthquakes

Niloufar Abolfathian, Eric J. Fielding, David Bekaert, Andrea Donnellan, & Simran S. Sangha

Submitted August 16, 2021, SCEC Contribution #11528, 2021 SCEC Annual Meeting Poster #108

Recent advances in data acquisition, analysis methods, and computational capabilities allow spatiotemporal estimations of stress and strain in high-resolution within the Earth’s crust. We analyze the interferometric synthetic aperture radar (InSAR) time-series to measure more than one year of postseismic surface deformation, and invert InSAR together with the Global Positioning System (GPS) to infer afterslip on faults near or in the main coseismic ruptures from the 2019 Mw 6.4 and 7.1 Ridgecrest sequence, utilizing Caltech-JPL Advanced Rapid Imaging and Analysis (ARIA) dataset. ARIA project has been systematically processing InSAR data from the Copernicus Sentinel-1 satellites recording more than 100 interferograms from each of the ascending track 64 and the descending track 71 every 6 and 12 days in the selected postseismic time period in the study area. Moreover, ARIA interferograms have recorded deformation since 2015 in this area, including more than 100 interferograms from each of the mentioned tracks, that image pre-earthquake deformation. GPS data also obtained from GeoGateway, which is a data product and analysis tool developed by NASA consisting of geodetic imaging products including GNSS (Global Navigation Satellite System). The estimated postseismic deformation is largely consistent with afterslip on the main right-lateral NW-SE rupture. The largest uplift and displacement in the afterslip model are located near the Mw 7.1 hypocenter. We also examine the associated deviatoric stress field inverting more than 4500 fault plane solutions within the same postseismic time period obtained from the Southern California Earthquake Data Center and estimate the 4D spatiotemporal stress field variations in the study area. The stress field estimations indicate higher extensional stress components in the NW of the main rupture shifting to higher compressional components in the SW adjacent to the Garlock fault, where these variations are mainly located shallower than ~4 km. Integrating the obtained afterslip, strain-rate and stress field, we investigate the locations with higher variations in the strain-rate and stress field, which ultimately help in detecting zones with higher stress accumulations that are potential for seismic hazard.

Key Words
stress, Ridgecrest, InSAR, postseismic deformation, slip distribution

Abolfathian, N., Fielding, E. J., Bekaert, D., Donnellan, A., & Sangha, S. S. (2021, 08). Spatiotemporal variations of stress and strain in the crust near 2019 Ridgecrest Sequence Earthquakes. Poster Presentation at 2021 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy