Seismic Swarm S20130325.1: Analysis of Activity Near Mogul, Nevada

The seismic swarm designated S20130325.1 occurred approximately 10 km south-southeast of Mogul, Nevada, between 05:44 UTC on 24 March 2013 and 06:46 UTC on 25 March 2013. Over this 25-hour period, 36 earthquakes were recorded, with event magnitudes ranging from -0.2 to 2.2 and focal depths primarily between 6 km and 12 km. The sequence exhibited a typical swarm pattern, featuring multiple small events clustered in time without a dominant mainshock, consistent with fluid migration or localized stress adjustments along pre-existing fault structures.

Event timing showed an initial sparse phase followed by heightened activity in the evening of 24 March, including several events above magnitude 1.0. Notable occurrences included a magnitude 2.2 event at 21:20:29 on 24 March at 11 km depth and a magnitude 1.9 event at 06:29:30 on 25 March at 10 km depth. Depths remained relatively consistent throughout, suggesting a compact source volume within the upper crust. The swarm concluded with lower-magnitude events, indicating a gradual decay in activity.

Mogul lies within the western Basin and Range Province, a region defined by active extensional tectonics driven by the broader Pacific-North American plate boundary. Normal faults dominate the structural framework, accommodating east-west extension at rates of several millimeters per year. This setting produces frequent microseismicity and occasional larger events, with historical records documenting recurrent earthquake swarms linked to fault interactions and possible hydrothermal influences.

Since 1 January 2000, the Mogul area has experienced 24 documented swarms. Yearly distribution includes three in 2003, one in 2004, four in 2005, one in 2007, seven in 2008, one in 2010, three in 2012, and four in 2013. These episodes underscore the region's persistent low-level seismic productivity, often occurring without escalation to damaging magnitudes.

Such swarms provide valuable data for understanding crustal deformation processes in tectonically active zones. Continued monitoring supports improved hazard assessment for nearby communities in the Reno metropolitan area.

References

SeismoSight internal swarm classification records.
USGS Earthquake Hazards Program regional tectonic summaries.