2019 M7.1 Ridgecrest earthquake slip distribution controlled by fault geometry inherited from Independence dike swarm

Faults often form through reactivation of pre-existing structures, developing geometries and mechanical properties specific to the system’s geologic inheritance. Competition between fault geometry and other factors (e.g., lithology) to control slip at Earth’s surface is an open question that is central to our knowledge of fault processes and seismic hazards. Here we use remote sensing data and field observations to investigate the origin of the 2019 M 7.1 Ridgecrest, California, earthquake rupture geometry and test its impact on the slip distribution observed at Earth’s surface. Common geometries suggest the fault system evolved through reactivation of structures within the surrounding Independence dike swarm (IDS). Mechanical models testing a range of fault geometries and stress fields indicate that the inherited rupture geometry strongly controlled the M 7.1 earthquake slip distribution. These results motivate revisiting the development of other large-magnitude earthquake ruptures (1992 M 7.3 Landers, 1999 M 7.1 Hector Mine) and tectonic provinces within the IDS. Faults responsible for the 2019 M7.1 Ridgecrest, California earthquake likely evolved through reactivation of pre-existing Independence dike swarm structures. The inherited rupture geometry strongly controlled the earthquake slip distribution.