Seismic Swarm S20241223.1: Analysis of Activity South of Goldfield, Nevada

A seismic swarm designated S20241223.1 was recorded 40 km south of Goldfield, Nevada, from 16:34 on 22 December 2024 to 23:56 on 24 December 2024. Over 55 hours and 22 minutes, the sequence comprised 49 earthquakes. All events were of low magnitude, with the largest reaching 2.0, and hypocentral depths remained shallow, ranging from 0 to 8 km.

The sequence began with a 0.4-magnitude event at 2 km depth. Subsequent activity included multiple events of magnitude 1.3 to 1.6 within the first 24 hours. Peak activity occurred on 23 December, featuring several 1.6-magnitude shocks at depths of 0–5 km. Magnitudes declined gradually toward the end of the swarm, with the final event registering 1.4 at 7 km depth on 24 December. The distribution shows a concentration of events between 1 and 4 km depth, consistent with shallow crustal processes typical of the region.

Regional Geological Setting

The swarm occurred within the Basin and Range province of western Nevada, characterized by extensional tectonics and normal faulting. This geologic framework produces frequent small-magnitude earthquake sequences. The area south of Goldfield lies near the intersection of regional fault systems associated with the Walker Lane shear zone, where right-lateral strike-slip motion accommodates part of the Pacific–North American plate boundary strain. Quaternary fault scarps and volcanic rocks of Miocene age dominate the local geology, reflecting long-term extension and episodic magmatism.

Goldfield itself developed during the early twentieth-century gold rush, with mining operations intersecting altered volcanic and sedimentary units. Historical records indicate that the broader region has hosted recurrent seismic swarms linked to fluid migration along faults rather than large mainshock-aftershock sequences.

Historical Swarm Context

Since 2000, nineteen swarms have been documented in the same area. Annual counts include single swarms in 2000, 2001, 2002, 2004, 2005, 2006, 2010, 2012, 2017, 2020, and 2021; two swarms each in 2007, 2011, 2015, and 2024. This pattern demonstrates persistent, low-level seismic energy release without escalation to damaging earthquakes.

The December 2024 swarm aligns with this established behavior. Its modest magnitudes and brief duration suggest a localized adjustment along pre-existing fractures, possibly driven by hydrothermal fluid movement common in the Basin and Range.

Implications and Monitoring

No damage or felt reports were associated with the sequence. Continued seismic monitoring by regional networks remains essential, given Nevada’s overall elevated seismicity. The shallow depths observed underscore the potential for minor ground shaking in future similar events, although current data indicate low hazard.

References
U.S. Geological Survey Earthquake Catalog (earthquake.usgs.gov)
Nevada Seismological Laboratory regional reports
SeismoSight internal swarm classification S20241223.1