Seismic Swarm S20150912.1 Near Indian Springs, Nevada

Seismic swarm S20150912.1 was recorded 59 km NNW of Indian Springs, Nevada, from 23:13 on 11 September 2015 until 12:03 on 13 September 2015. Over this 36-hour 49-minute period, 41 earthquakes occurred, all of low magnitude and shallow depth.

The sequence began with an event of magnitude -0.7 at 9 km depth. Subsequent events maintained a narrow magnitude range between -0.9 and 0.3, with the majority falling between -0.8 and -0.2. Depths clustered between 4 km and 11 km, averaging near 8–9 km. Activity showed no single dominant shock; instead, events occurred in clusters separated by brief quiet intervals, a pattern typical of swarm behavior rather than mainshock-aftershock sequences.

This swarm represents the eighth such episode documented in the region since 2000. Earlier swarms took place in 2000 (two events), 2002 (two events), 2008, 2009, 2012, and one prior swarm in 2015. The repetition indicates persistent, localized stress release along faults in this part of southern Nevada.

The location lies within the Basin and Range Province, where ongoing crustal extension produces numerous normal faults. The southern Great Basin experiences distributed deformation linked to the interaction between Pacific-North American plate motion and the Walker Lane belt. Shallow crustal earthquakes in this setting commonly result from fluid movement or aseismic slip that perturbs nearby fault segments. Depths recorded during the swarm align with the brittle-ductile transition zone expected for the local geothermal gradient.

No damage or felt reports accompanied the swarm, consistent with the microseismic character of the events. Continued monitoring of the area remains important because recurrent swarms can signal evolving stress conditions on nearby structures. The 2015 sequence adds to the record of episodic, low-magnitude seismic activity that characterizes this portion of the Basin and Range.