Using Sentinel-1 InSAR time series to characterize postseismic motions around the 2021 Mw 5.3 Calipatria earthquake, Imperial Valley, CA
Katherine A. Guns, Kathryn Materna, & Andrew J. BarbourSubmitted September 7, 2025, SCEC Contribution #14435, 2025 SCEC Annual Meeting Poster #TBD
The Imperial Valley in southernmost California is home to a network of primary and secondary faults, all of which can be impacted by the high heat flow, shallow crust, and volcanic and hydrothermal activity that characterizes the region. Previous studies of earthquakes in this active area have shown signs of significant pre- and post-mainshock aseismic deformation as observed by geodetic data (including for the 2005 Mw 5.1 Salton Sea (e.g., Lohman & Simons, 2007) and 2020 Mw 4.9 Westmorland events (e.g., Sirorattanakul et al., 2022)), in addition to the common occurrence of slow slip aseismic creep events nearby (e.g., Materna et al., 2024). Investigating the causes of aseismic deformation and characterizing its effect on estimates of seismic hazard along faults is a primary goal of earthquake science. Here, I seek to identify the causes of postseismic deformation following the June 5th, 2021 Mw 5.3 Calipatria earthquake which occurred ~3 km southeast of the Salton Sea and on the southern boundary of the Salton Sea geothermal field. Interferometric Synthetic Aperture Radar (InSAR) observations are well-suited to measuring these fault processes due to their image-based spatial continuity and their sensitivity to shallow deformation. I apply time series methods to investigate shallow postseismic motions around the epicenter of the Mw 5.3 event to better understand the role postseismic processes may play in the earthquake cycle in this unique faulting environment. I process 4.5 years of descending track and 2 years of ascending track Sentinel-1 InSAR time series and use a combination of 1D and 2D time series trajectory modeling to characterize the temporally evolving postseismic displacements. InSAR time series show spatially limited, but clear postseismic behavior on the order of >5-10 mm (LOS) near the epicentral region in the first ~month following the event, with a possible ongoing signal in the years following the event. This time series analysis will inform fault slip modeling for both the co- and postseismic displacements and an assessment of ongoing stress changes on neighboring faults in the Salton Sea area.
Key Words
InSAR, GNSS, Time Series, Aseismic Processes, Postseismic Deformation, Salton Trough, Fluid Flow
Citation
Guns, K. A., Materna, K., & Barbour, A. J. (2025, 09). Using Sentinel-1 InSAR time series to characterize postseismic motions around the 2021 Mw 5.3 Calipatria earthquake, Imperial Valley, CA. Poster Presentation at 2025 SCEC Annual Meeting.
Related Projects & Working Groups
Tectonic Geodesy
