Seismic Swarm S20161118.1: Analysis of Activity Near Indian Springs, Nevada
A seismic swarm designated S20161118.1 occurred 34 km west-northwest of Indian Springs, Nevada, from 02:36 on 18 November 2016 until 12:39 on 19 November 2016. Over this 34-hour period, 31 earthquakes were recorded. The events clustered at shallow depths between 6 and 9 km, with magnitudes ranging from -0.4 to 2.3. The sequence began with numerous microearthquakes below magnitude 1.0, followed by a peak event of magnitude 2.3 at 09:12 on 18 November. Subsequent activity included several events between magnitude 0.4 and 0.7 before tapering off, with the final recorded event at magnitude -0.1 on 19 November.
This swarm reflects typical patterns of clustered, low-magnitude seismicity in the region. All events remained well below levels that would produce felt shaking or surface effects. Depths consistently near 8 km suggest activation along shallow crustal structures common in extensional settings.
The Indian Springs area lies within the Basin and Range Province of southern Nevada, where ongoing crustal extension along normal faults drives persistent seismic activity. This tectonic regime produces distributed faulting rather than large single ruptures, favoring swarm-like sequences over isolated mainshock-aftershock patterns. Historical records since 2000 document 35 swarms in the immediate vicinity, distributed across multiple years with notable concentrations in 2002 (7 swarms), 2008 (5 swarms), and both 2009 and 2015 (4 swarms each). These episodes underscore the area's long-term susceptibility to episodic microseismicity.
Such swarms provide valuable data on local stress conditions and fault interactions without posing significant hazard. Continued monitoring supports refined understanding of Nevada's seismic character within the broader western United States extensional domain.
References
SeismoSight internal swarm classification records
USGS Earthquake Catalog (Nevada regional data)
Nevada Bureau of Mines and Geology tectonic summaries