Seismic Swarm S20160228.1: Activity Near Beatty, Nevada
A seismic swarm designated S20160228.1 occurred approximately 45 km east-southeast of Beatty, Nevada, between 09:36 on 27 February 2016 and 13:55 on 28 February 2016. In total, 38 earthquakes were recorded over 28 hours and 18 minutes. The events were characterized by very low magnitudes, predominantly between -0.3 and 1.1, with focal depths ranging from 3 km to 10 km. Most activity clustered between 6 km and 9 km depth, consistent with shallow crustal faulting in the region.
The sequence began with a magnitude 0.0 event at 6 km depth on 27 February. Subsequent events remained small until early 28 February, when a magnitude 0.8 earthquake occurred at 9 km depth, followed by additional microearthquakes. Peak activity included a magnitude 1.1 event at 9 km depth around 04:34 on 28 February. The swarm concluded with a magnitude 0.0 event at 8 km depth at 13:55. No single mainshock dominated the sequence; instead, the pattern reflected distributed, low-energy release typical of swarm behavior.
This swarm took place within the Basin and Range Province of southwestern Nevada, a tectonically active extensional environment marked by north-south trending normal faults and Quaternary volcanic features. The area lies near the transition to the Walker Lane shear zone, where right-lateral strike-slip motion accommodates part of the Pacific-North America plate boundary deformation. Historical faulting and volcanic activity associated with the Timber Mountain caldera complex contribute to elevated seismicity rates. Depths observed in the swarm align with the brittle-ductile transition zone in this portion of the crust.
Since 2000, 38 swarms have been documented in the same locale. Yearly counts include five in 2000, seven in 2002, two in 2003, two in 2005, one in 2006, two in 2007, seven in 2008, four in 2009, three in 2010, one in 2012, one in 2014, and three in 2015. These recurrent swarms indicate persistent, low-level tectonic strain release without progression to larger, damaging earthquakes.
References
- SeismoSight internal swarm classification records
- USGS Earthquake Catalog (general regional seismicity)
- Nevada Bureau of Mines and Geology (tectonic framework of Nye County)