Linking Fault Slip and Near-Surface Deformation on the Southern San Andreas Fault at Mecca Hills
Asenath Kwagalakwe, Eileen L. Evans, Gladys Pantoja, & Allen M. GontzSubmitted September 7, 2025, SCEC Contribution #14715, 2025 SCEC Annual Meeting Poster #TBD
Understanding how active fault deformation intersects with the surface is critical for seismic hazard, including anticipating where the surface will rupture in earthquakes and for accurate estimation of fault slip. However, due to the complex and spatially variable nature of the near-surface, the shallowest portion of the crust is poorly understood with respect to tectonic deformation and faulting. Here, we investigate how active tectonic faulting is accommodated in the near-surface on the Coachella Valley segment of the southern San Andreas Fault (sSAF) at Painted Canyon in Mecca Hills, California. The Coachella Valley segment accommodates 14-19 mm/yr of long-term slip. Geodetic observations from Global Navigation Satellite Systems (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) suggest that the segment experiences partial creep of ~4mm/yr, which may be accommodated during slow creep events and/or triggered creep following nearby earthquakes. However, the apparent location of partial creep on the sSAF at Painted Canyon is offset by ~200 m from the mapped trace of the fault, suggesting potentially complex strain partitioning near the surface. We image the near-surface (<5 m) with Ground Penetrating Radar (GPR), and we reoccupy an existing GNSS array, last surveyed in 2014, which crosses both the main fault trace and the location of previously identified creep. Updated GNSS velocities may reveal where interseismic deformation is concentrated and how deformation may have changed.
Citation
Kwagalakwe, A., Evans, E. L., Pantoja, G., & Gontz, A. M. (2025, 09). Linking Fault Slip and Near-Surface Deformation on the Southern San Andreas Fault at Mecca Hills. Poster Presentation at 2025 SCEC Annual Meeting.
Related Projects & Working Groups
Tectonic Geodesy
