Towards an InSAR Catalog of Creep Events on the Imperial Fault
Description:
The Imperial Fault (IF), located in Southern California’s Imperial Valley, is one of the fastest partially-creeping faults in California (Field et al., 2015). Deformation models suggest right-lateral slip rates of 20-35 mm/yr, showing the IF poses a significant source of hazard. The IF hosted Mw7.0 and Mw6.5 earthquakes in 1940 and 1979 (Rockwell & Klinger, 2013; King & Thatcher, 1998). Aseismic slip is a frequent mode of seismic moment release on the IF, and can be classified into distinct creep modes: afterslip, triggered slip (in response to teleseismic earthquakes), spontaneous slip, and continuous creep. All four of these modes are present on the IF. Studies show centimeter-scale episodic creep events occur several times a decade (Donnellan et al., 2014; Materna et al., 2024), and the depth of creep is suggested to be about 3-4 km (Lindsey & Fialko, 2016).
To study the time-dependence and kinematics of aseismic slip on the IF, we utilize ten years of Sentinel-1 InSAR data, combined with GNSS and creepmeters, to test kinematic and dynamic models of creep events. Using ISCE, we construct nearest neighbor interferograms and visually inspect each for evidence of fault creep. Using deformation profiles of creep events identified in InSAR, we perform MCMC simulations of dislocation models to constrain depth of creep events and the slip of each dislocation. The scaling between slip and depth can be used to constrain stress drop. By comparing the stress drop to the stressing rate calculated from backslip arguments, a prediction of recurrence time can be developed (Loveless & Meade, 2011). This study will also address the geographical segmentation of creep, temporal correlation, depth of creep events, and scaling relationships between creep event length, depth, duration, and slip. Understanding the kinematics and dynamics of creep events on the IF will help quantify the seismic hazard associated with one of California’s most active faults. Such findings have implications for stress transfer on faults in the area (i.e., Brawley Fault) and a more unified understanding of the drivers of slip in Southern California.
Session: Predictability of Seismic and Aseismic Slip: From Basic Science to Operational Forecasts [Poster]
Type: Poster
Date: 4/16/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: M. Morow
Student Presenter: Yes
Invited Presentation:
Poster Number: 47
Authors
M. Morow Tan Presenting Author Corresponding Author M.Tan@colorado.edu University of Colorado Boulder |
Kathryn Materna Kathryn.Materna@colorado.edu University of Colorado Boulder |
Roger Bilham Roger.Bilham@colorado.edu University of Colorado Boulder |
Daniel Gittins Daniel.Gittins@colorado.edu University of Colorado Boulder |
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Towards an InSAR Catalog of Creep Events on the Imperial Fault
Session
Predictability of Seismic and Aseismic Slip: From Basic Science to Operational Forecasts