Seismic Swarm S20030525.1 Near Beatty, Nevada

The seismic swarm designated S20030525.1 occurred approximately 43 km east-southeast of Beatty, Nevada, in the southwestern portion of the state. It began at 10:02 UTC on 24 May 2003 and concluded at 02:59 UTC on 29 May 2003, spanning 112 hours and 56 minutes. During this interval, 88 earthquakes were recorded.

This event cluster reflects typical swarm behavior in the region, with the majority of events registering negative or low positive magnitudes and focal depths concentrated between 7 km and 11 km. The largest event reached magnitude 2.2 on 24 May at 16:16 UTC at a depth of 11 km. Subsequent activity included several events between magnitude 1.0 and 1.8, while most others remained below magnitude 0.5. Depths showed minor variation, occasionally reaching as shallow as 1–3 km or extending to 12 km, consistent with upper-crustal processes driven by regional extension.

The swarm exhibited episodic clustering, with elevated activity on 24 and 25 May followed by a gradual decline through 28 May. Such patterns align with fluid migration or aseismic slip triggering mechanisms commonly observed in the Basin and Range Province.

Since 1 January 2000, eleven swarms have been identified in the area according to SeismoSight internal classification. Earlier episodes occurred in 2000 (four swarms) and 2002 (seven swarms), indicating recurrent low-level seismic unrest.

Beatty lies within the southern Nevada portion of the Basin and Range extensional province, where normal faulting accommodates ongoing crustal stretching. The local geology features Quaternary alluvium overlying Paleozoic carbonates and Tertiary volcanic rocks, with proximity to the Walker Lane shear zone enhancing strain accumulation. Historical seismicity in this sector remains moderate, influenced by both tectonic and possible hydrothermal factors near the Nevada National Security Site boundary.

References

SeismoSight internal swarm classification records for S20030525.1.