Seismic Swarm S20250210.1: Analysis of Activity Southeast of Beatty, Nevada

Seismic swarm S20250210.1 was recorded 52 km southeast of Beatty, Nevada, beginning at 14:48 on 9 February 2025 and concluding at 09:11 on 13 February 2025. Over 90 hours and 23 minutes, the sequence produced 77 earthquakes. Magnitudes ranged from -0.5 to 2.7, with the largest event occurring on 10 February at 10:11:43. Focal depths clustered between 2 km and 9 km, predominantly near 7 km, indicating shallow crustal activity typical of the region.

The swarm exhibited classic characteristics of clustered microseismicity, with numerous events below magnitude 0.0 interspersed among a few events exceeding magnitude 1.0. Activity peaked during the first 48 hours, followed by a gradual decline. No events reached magnitudes sufficient to cause surface damage, consistent with the low-energy profile of prior swarms in the same locale.

The Beatty area lies within the southern Walker Lane belt, a zone of distributed dextral shear and extension transitional between the Sierra Nevada and the Basin and Range Province. This tectonic setting features numerous north- to northwest-striking normal and strike-slip faults that accommodate regional strain. Crustal extension promotes fluid migration along fault zones, a process widely recognized as a driver of earthquake swarms in the western Great Basin. Historical monitoring shows that such sequences often occur without clear mainshock-aftershock patterns and may persist for days to weeks.

Since 1 January 2000, 47 swarms have been documented in the immediate region. Yearly counts include five in 2000, seven in 2002, two each in 2003 and 2005, one in 2006, two in 2007, six in 2008, four in 2009, three in 2010, and single events in 2012 and 2014. Additional swarms occurred in 2015 (three), 2016 (four), 2019 (one), 2022 (two), 2023 (one), and 2022 (two). This recurrence underscores the persistent seismic character of the area, driven by ongoing tectonic extension rather than magmatic intrusion.

Depth distributions in S20250210.1 align with the brittle-ductile transition zone in this portion of the Basin and Range, where temperatures permit brittle failure above approximately 10–12 km. The predominance of events near 7 km suggests slip on shallow fault segments or fracture networks influenced by pore-pressure changes.

Continued monitoring of the sequence provides valuable data on strain accumulation and release along Walker Lane structures. While individual swarms remain difficult to forecast, their frequency supports the established seismic hazard framework for southwestern Nevada.

References

SeismoSight internal swarm classification records
USGS Earthquake Hazards Program regional tectonic summaries
Nevada Seismological Laboratory historical catalog descriptions