Seismic Swarm S20100202.1: Analysis of Activity Near Beatty, Nevada

Seismic swarm S20100202.1 occurred approximately 44 km east-southeast of Beatty, Nevada, within the tectonically active Basin and Range Province. The sequence began at 03:32 UTC on 1 February 2010 and concluded at 09:16 UTC on 4 February 2010, spanning 77 hours and 43 minutes. During this interval, 44 earthquakes were recorded, with magnitudes ranging from -0.7 to 1.1 and focal depths primarily between 4 km and 11 km.

The events exhibited typical swarm characteristics, featuring a gradual onset followed by episodic bursts rather than a dominant mainshock-aftershock pattern. The largest event, magnitude 1.1, occurred early in the sequence on 1 February at 10:10 UTC. Subsequent activity consisted predominantly of microearthquakes below magnitude 0.0, with many registering negative magnitudes indicative of very small energy release. Depths remained shallow throughout, consistent with brittle failure in the upper crust of this extensional regime.

Temporal clustering was evident, with heightened activity on 1 February concentrated between 09:48 and 12:31 UTC. Later phases on 2 and 3 February showed more dispersed timing, tapering to isolated events by 4 February. This pattern aligns with fluid migration or aseismic slip processes often observed in swarm sequences within the Walker Lane tectonic belt.

The broader region surrounding Beatty has experienced recurrent seismic swarms. Since 1 January 2000, 30 swarms have been documented in the area. Yearly distribution includes five in 2000, seven in 2002, two in 2003, two in 2005, one in 2006, two in 2007, seven in 2008, and four in 2009. These episodes reflect ongoing extensional tectonics driven by normal faulting along range-front structures.

Geologically, the locale lies near the southern Nevada volcanic field and the margins of the Nevada National Security Site. Quaternary fault scarps and Holocene alluvium indicate recent deformation. Crustal extension rates average 1–2 mm per year, accommodated by distributed fault systems that produce both isolated events and swarm-like sequences.

The shallow depths and low magnitudes recorded in S20100202.1 suggest minimal surface rupture potential, though such activity contributes to long-term seismic hazard assessments for nearby infrastructure and communities.

References

SeismoSight internal swarm classification database.
USGS Earthquake Catalog for regional context.
Nevada Seismological Laboratory historical records.