Seismic Swarm S20120604.1: Analysis of Activity Near Beatty, Nevada

Seismic swarm S20120604.1 was recorded 57 km east-northeast of Beatty, Nevada, beginning at 13:21 UTC on 3 June 2012 and concluding at 15:26 UTC on 4 June 2012. Over this 26-hour period, 28 earthquakes were detected, with magnitudes ranging from -1.3 to 0.8 and focal depths between 0 and 10 km. The events clustered tightly in both space and time, exhibiting the characteristic pattern of a swarm without a dominant mainshock.

The sequence opened with a magnitude 0.8 event at 8 km depth. Subsequent activity included numerous microearthquakes, many with negative magnitudes, occurring at shallow crustal levels. Notable events comprised a magnitude 0.7 quake at 8 km depth on 3 June at 18:12 and several magnitude -1.3 shocks on 4 June. Depths remained predominantly between 5 and 8 km after the initial hours, consistent with brittle failure in the upper crust.

This swarm fits the regional tectonic setting of southwestern Nevada. The area lies within the Basin and Range Province, where ongoing east-west extension produces normal faulting along north-south trending structures. Beatty occupies the transition between the Sierra Nevada and the Great Basin, near the Walker Lane shear zone that accommodates a portion of Pacific-North America plate motion. Historical seismicity in the region reflects this extension, with frequent small events and occasional swarms linked to fault segments and volcanic features such as those associated with the Timber Mountain caldera complex.

Since 2000, twelve swarms have been documented in the immediate vicinity, occurring in 2000 (two events), 2002 (three), 2005 (three), 2008 (two), and 2009 (two). These recurrent swarms indicate persistent low-level strain release along favorably oriented faults without producing larger mainshock-aftershock sequences.

The 2012 swarm added to this pattern, reinforcing the area’s status as a zone of distributed microseismicity. No damage or felt reports were associated with the events, underscoring their minor energetic release.

References
Nevada Seismological Laboratory, University of Nevada, Reno – Regional seismic catalog.
United States Geological Survey Earthquake Hazards Program – Basin and Range tectonics summary.
SeismoSight internal swarm classification database.