Seismic Swarm S20220519.1 Near Indian Springs, Nevada: Geological Context and Event Analysis
Earthquake swarm S20220519.1 was recorded 44 km northwest of Indian Springs, Nevada, from 05:37 on 18 May 2022 to 11:25 on 19 May 2022. Over 29 hours and 47 minutes, the swarm produced 37 earthquakes. Magnitudes ranged from -0.5 to 0.7, with focal depths between 3 km and 13 km. The sequence began with a magnitude -0.5 event at 13 km depth and concluded with a magnitude 0.1 event at 6 km depth. Most events clustered between 4 km and 6 km depth, with a few deeper occurrences up to 13 km.
This swarm aligns with patterns observed in the Basin and Range province, where extensional tectonics drive frequent small-magnitude seismicity. The area northwest of Indian Springs lies within a region of active normal faulting associated with the southern Nevada seismic belt. Shallow crustal depths in the recorded events are consistent with the brittle deformation typical of the upper 15 km of the crust in this extensional setting.
Historical records since 2000 indicate 46 swarms in the vicinity. Annual counts include 4 in 2000, 7 in 2002, 2 in 2003, 2 in 2005, 1 in 2006, 2 in 2007, 6 in 2008, 5 in 2009, 3 in 2010, 2 in 2012, 1 in 2014, 5 in 2015, 4 in 2016, 1 in 2019, and 1 in 2022. These recurring swarms reflect episodic strain release along distributed faults rather than mainshock-aftershock sequences.
Swarm activity of this scale typically involves low-energy events that do not indicate imminent larger earthquakes. The tight spatiotemporal clustering and narrow magnitude range observed here match characteristics of fluid-influenced or aseismic-slip-triggered swarms common in the region. Depths predominantly under 10 km suggest involvement of the shallow seismogenic zone influenced by regional extension rates of approximately 1 cm per year.
No damage or felt reports were associated with these microearthquakes. Continued monitoring supports improved understanding of background seismicity rates in southern Nevada, aiding regional hazard assessments.
References
SeismoSight internal swarm classification S20220519.1 dataset.
USGS Earthquake Hazards Program regional tectonic summaries for Nevada.
Nevada Seismological Laboratory historical earthquake catalogs.