Analysis of Seismic Swarm S20080922.2 Near Beatty, Nevada

Seismic swarm S20080922.2 was recorded 45 km east of Beatty, Nevada, commencing at 16:24 on 21 September 2008 and concluding at 07:12 on 1 October 2008. Over a duration of 230 hours and 47 minutes, the swarm comprised 133 earthquakes. This sequence represents one of four swarms documented in the region during 2008.

Analysis of the first 100 events reveals predominantly low-magnitude activity. Magnitudes ranged from -0.6 to 0.7, with the majority falling between -0.5 and 0.3. Depths clustered tightly around 8–9 km, though values extended from 2 km to 10 km. The initial event on 21 September at 16:24:43 registered magnitude -0.2 at 7 km depth. Subsequent events on 22 September showed a concentration of activity between 04:59 and 23:09, including several magnitude 0.6–0.7 shocks at depths of 9–10 km. Later events through 27 September maintained similar characteristics, with occasional shallower occurrences at 2–4 km. No events exceeded magnitude 0.7 within the examined subset.

Historical records indicate 23 swarms in the area since 1 January 2000. Annual counts include five in 2000, seven in 2002, two in 2003, two in 2005, one in 2006, two in 2007, and four in 2008. These recurrent swarms reflect persistent seismic patterns in the locale.

The region lies within the Basin and Range Province of southwestern Nevada, where extensional tectonics drive normal faulting and distributed crustal deformation. This geological setting produces frequent small-magnitude earthquake sequences, often in swarms rather than mainshock-aftershock patterns. Depths of 8–10 km align with typical brittle failure zones in the upper crust of this province. Proximity to the Nevada National Security Site further contextualizes long-term monitoring of both natural and induced seismicity.

References

SeismoSight internal swarm classification data
USGS Earthquake Hazards Program regional tectonic summaries
Nevada Seismological Laboratory historical earthquake catalogs