Earthquake Swarm S20150214.1: Seismic Activity Near Beatty, Nevada

Earthquake swarm S20150214.1 was recorded beginning at 02:16 on 14 February 2015 and concluding at 11:43 on 23 February 2015. The events occurred 49 km west-northwest of Beatty, Nevada, with a total of 434 earthquakes detected over 225 hours and 26 minutes.

Analysis of the first 100 events reveals a rapid onset of activity. The sequence opened with a magnitude 3.2 earthquake at 14 km depth. Within twelve minutes, a magnitude 4.8 event occurred at 17 km depth, representing the largest shock in the initial cluster. Subsequent events displayed magnitudes predominantly between 0.0 and 2.8, with depths concentrated between 6 km and 17 km. Shallow events below 5 km were infrequent, while several micro-earthquakes registered negative magnitudes down to -0.1. The distribution shows an initial high-energy phase in the first hour, followed by a sustained sequence of smaller events with occasional magnitude 2+ shocks, such as the magnitude 3.2 at 03:34 and magnitude 2.8 at 04:53.

This swarm aligns with the tectonic setting of western Nevada. The region lies within the Basin and Range Province, where crustal extension along normal faults produces recurrent seismic swarms. Beatty is situated near the southern Walker Lane belt, a zone of distributed shear that accommodates Pacific-North America plate motion. Historical records indicate the area has experienced multiple swarms linked to both tectonic strain and possible hydrothermal influences associated with nearby volcanic fields.

Since 1 January 2000, ten earthquake swarms have been documented in the vicinity. These occurred in 2000, 2001, 2002, 2004, 2005, 2006, 2010 (two swarms), and 2011 (two swarms). The 2015 swarm fits this pattern of episodic activity, with event counts and durations varying across prior episodes but sharing similar magnitude ranges and focal depths.

The geological history of the Beatty area reflects long-term extension and volcanism. Miocene to Pleistocene basaltic and rhyolitic eruptions have left a complex subsurface of fractured volcanic rocks and sedimentary basins that facilitate fluid migration and triggered seismicity. Ongoing monitoring continues to track such swarms as indicators of regional strain accumulation.

References

SeismoSight internal swarm classification database.
USGS Earthquake Catalog.
Nevada Seismological Laboratory regional reports.