Heat flow controls on the Mw7.1 July 6, 2019 Ridgecrest Earthquake postseismic deformation from Sentinel-1 Burst Overlap Interferometry

Yohai Magen, Gidon Baer, Alon Ziv, Asaf Inbal, & Ran N. Nof

Published September 8, 2024, SCEC Contribution #13632, 2024 SCEC Annual Meeting Poster #087

The July 2019 Ridgecrest earthquake sequence struck the Eastern California Shear Zone, consisting of an Mw6.4 foreshock and an Mw7.1 mainshock, and ruptured a complex network of orthogonal faults. In this study, we measure the co- and post-seismic deformation of this sequence utilizing the Burst Overlap Interferometry (BOI) technique along with conventional Interferometric Synthetic Aperture Radar (InSAR). Showcasing the ability of BOI to retrieve centimeter-scale displacement signals over postseismic time periods as short as a few months, the BOI technique captures displacement in the satellite's along-track direction and provides crucial information into the post-seismic deformation field that cannot be retrieved by traditional InSAR and sparse GNSS networks. Our BOI data reveals up to 4 cm of displacement in the along-track direction, located 10 km north of the northern tip of the seismic rupture, and 3 cm across the co-seismically active faults. These results discount the likelihood of significant shallow afterslip near the mainshock hypocenter, suggesting that poroelastic rebound accounts for the notable post-seismic line-of-sight (LOS) deformation near the mainshock rupture. Based on aftershock moment tensor distribution, surface rupture observations, and simple forward modeling, we hypothesize that the post-seismic deformation north of the Ridgecrest rupture is caused by a north-trending off-Ridgecrest normal aseismic fault, triggered by the Ridgecrest earthquake. Additionally, our observations indicate that both deformation and seismic activity exhibit slower temporal decay with increasing distance from the Coso geothermal area. This decay pattern is influenced by the crust's mechanical properties, which are modified by the enhanced heat flow at Coso, thereby suppressing deformation and seismicity and ultimately controlling their temporal evolution.

Citation
Magen, Y., Baer, G., Ziv, A., Inbal, A., & Nof, R. N. (2024, 09). Heat flow controls on the Mw7.1 July 6, 2019 Ridgecrest Earthquake postseismic deformation from Sentinel-1 Burst Overlap Interferometry. Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy