Poster #115, Stress and Deformation Over Time (SDOT)

Modeling of postseismic deformation following the 2019 Ridgecrest earthquake sequence

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Poster Presentation

2020 SCEC Annual Meeting, Poster #115, SCEC Contribution #10423
The 2019 Ridgecrest earthquake sequence culminated in the largest seismic event in California since the 1999 Mw 7.1 Hector Mine earthquake. Here we use Sentinel-1 and Cosmo-SkyMed (CSK) InSAR, as well as GNSS data to study the postseismic deformation following the mainshock. InSAR measurements from both ascending and descending satellite orbits reveal clear postseismic deformation during the observation period from a few days after the mainshock to July, 2020. Combining data from different view geometries, we decompose the observed range changes into E-W and vertical components. The horizontal E-W postseismic deformation field is characterized by eastward motion east of the Mw 7.1 rupture tr...ace and westward motion west of the fault trace. The vertical component is mainly characterized by uplift near the Mw 7.1 epicenter and the southwest corner of the Mw 6.4 and the Mw 7.1 fault junction, where the rupture produced coseismic dilatancy in a releasing bend and rupture intersection, respectively. The near-field InSAR measurements are suggestive of both afterslip and poroelastic rebound following the 2019 Ridgecrest earthquakes. The InSAR time series also exhibit different relaxation times around the fault zone, indicative of different fault zone rheologies or relaxation mechanisms. GNSS measurements from the PBO networks also reveal clear postseismic transient deformation in the far-field (>100 km from the epicenter), which is likely mainly due to viscoelastic relaxation in the lower crust and upper mantle. We are currently developing joint models that will incorporate both afterslip, poroelastic rebound and viscoelastic relaxation to probe the mechanical properties (e.g. frictional properties hydrological diffusivity), of the fault zone and bulk rheology of the lower crust and upper mantle of the Mojave Desert. We will be presenting the modeling results at the meeting.