Analysis of the 2021 Milford, Utah earthquake swarm: Enhanced earthquake catalog and migration patterns

An earthquake swarm occurred in Spring 2021 south-central Utah near the town of Milford. The University Seismograph Stations located 125 earthquakes between March 19 and May 10 with magnitudes ranging from 0.5 to 3.2. We implement a matched-filter technique order identify additional that went undetected during routine network location. network-located are used as templates cross-correlated continuous data for dates Feb 17—June 10. This time period corresponds approximately 1 month before began through after it ended. For analysis, we rely heavily on station FOR1, which is within 5 km most template events. Four other stations 20–30 events provide supplement closest station. implementation results detection over 600 addition original catalog one largest swarms ever recorded Utah, no previous large have been this use HypoDD obtain relative double-difference locations Both relocations suggest fault dipping west beneath mountain range, opposite typical Basin Range normal faults dip alluvial valleys. Moment tensors five show faulting consistent west-dipping seen seismicity. Hydrothermal features area, including geothermal power plant, fluids may be contributing factor triggering. examine role by exploring bounds diffusion parameters investigating spatial migration characteristics conclude result heterogenous stress conditions prefractured region.