Earthquake-triggered displacements in the central Salton Trough reveal wide range of slip modes

Kathryn Materna, & M. Morow Tan

Submitted September 7, 2025, SCEC Contribution #14793, 2025 SCEC Annual Meeting Poster #TBD

Fine-scale geodetic imaging of large earthquakes is increasingly revealing a complex spectrum of coseismic interactions between faults in the near, medium, and far fields. While it has long been recognized that earthquakes can be triggered through static or dynamic stresses, recent observations from large earthquakes in California, Turkiye, Mexico, and Haiti show that a wide range of aseismic deformation can also be triggered by coseismic slip. The triggered deformation ranges from small to large displacements, on minor and major faults, in the near and far fields. Potential processes for this deformation include frictional slip on seismogenic faults, movement on secondary faults, dynamically triggered slip, displacement driven by differential subsidence or lateral spreading, and the bending of compliant fault zones due to static stresses. We investigate a new entry in this spectrum of triggered slip using InSAR observations of the 2010 El Mayor Cucapah earthquake in northern Mexico and southern California. We utilize UAVSAR and Envisat data over the entire Imperial Valley to identify dozens of unrecognized examples of triggered slip at 50-100 km epicentral distances. We model InSAR displacement profiles as slip in an elastic medium using a nonlinear inversion technique, and we compare this displacement to interseismic loading from nearby faults, geodetic strain rate orientations, geologic interpretations of the structural pull-apart basin, and the interseismic vertical velocity field. This allows us to model the strength of the shallow subsurface, identify modes of triggered slip in the Earth’s crust, and better understand the full deformation potential of large earthquakes in the medium to far field.

Citation
Materna, K., & Tan, M. (2025, 09). Earthquake-triggered displacements in the central Salton Trough reveal wide range of slip modes. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy