Seismic Swarm S20060505.1 near Hawthorne, Nevada

Seismic swarm S20060505.1 occurred approximately 34 km south-southwest of Hawthorne, Nevada, within the tectonically active Walker Lane belt. This zone accommodates right-lateral shear and distributed normal faulting between the Pacific and North American plates, consistent with the broader extensional regime of the Basin and Range Province. The swarm initiated at 06:36 on 5 May 2006 and concluded at 21:06 on 6 May 2006, spanning 38 hours and 29 minutes during which 30 earthquakes were recorded.

The sequence featured a mainshock of magnitude 4.3 at 14 km depth, followed by numerous smaller events clustered at depths primarily between 10 km and 17 km. Magnitudes ranged from 0.7 to 4.3, with the majority below 2.0. Notable events included a magnitude 2.9 at 14 km depth roughly three hours after the mainshock and several magnitude 1.3–1.9 shocks distributed throughout the first day. Activity tapered on 6 May, ending with a magnitude 1.1 event at 17 km depth.

This swarm reflects typical behavior in the Hawthorne region, where fluid migration or minor stress perturbations along existing faults can trigger clustered seismicity without a single dominant mainshock-aftershock pattern. Depths indicate brittle failure within the mid-crust, aligning with regional fault geometries that include both strike-slip and normal components.

Historical records since 1 January 2000 document five swarms in the same area. Earlier episodes occurred in 2001 (two swarms) and 2004 (two swarms), with the 2006 event representing the fifth. Such recurrent swarms underscore the persistent seismic hazard in western Nevada, where low-to-moderate magnitude sequences contribute to long-term strain release.

References

• USGS Earthquake Catalog
• Nevada Seismological Laboratory regional reports
• Walker Lane tectonic summaries (USGS Professional Papers)