Examples of fault steps controlling event migration in seismic swarms

This study provides spatiotemporal constraints on seismicity within fault zones and identifies key links between fault step and event migration. We show that event distributions in seismic swarms can image stepping geometries reminiscent of relay zones commonly observed along fault zones. Earthquake migration can propagate across steps, indicating a transfer of deformation, but can be obstructed by others. Preliminary quantitative results show that whether a step transfers or blocks deformation depends on the separation between the bounding segments relative to the maximum magnitude of the events. These findings support the importance of understanding the role of internal fault geometry on seismicity and show that high accuracy event locations provide a critical understanding of seismicity.