Swarms and Foreshocks in the SAF system
Xiaowei ChenPublished September 8, 2024, SCEC Contribution #14047, 2024 SCEC Annual Meeting Poster #164
Earthquakes strongly cluster in space and time. There are three basic types of clusters: mainshock-aftershocks, foreshock-mainshock-aftershocks, and earthquake swarms. While aftershocks are commonly understood as triggering due to stress transfer from the mainshock, the triggering processes of foreshocks and earthquake swarms are not well understood. Using spectral analysis, low spectral stress drop is found for a cluster of immediate foreshocks of the M7 Ridgecrest earthquake, which is consistent previous observations of low spectral stress drop for foreshocks of three other M7 mainshocks in southern California that have been interpreted to reflect possible changes in fluid distributions in localized cracks due to precursory creep. In contrast, the immediate foreshocks of larger events during some earthquake swarms tend to have higher spectral stress drops, suggesting stronger earthquake interaction needed to break stronger asperities within complex fault systems.
In addition to spectral variations, the spatial distributions of clustering properties throughout the SAF system are explored using statistical methods. Comparison of relationship between swarm duration and migration velocities from different regions in SAF suggests possible relationship between fault zone rheology and dominant triggering processes. Fault zones with more complex structure are more likely to have swarm and foreshock occurrence. Updated results will be presented at the workshop.
Citation
Chen, X. (2024, 09). Swarms and Foreshocks in the SAF system. Poster Presentation at 2024 SCEC Annual Meeting.
Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)
