Seismic Swarm S20231230.1 Near Reno, Nevada
A seismic swarm designated S20231230.1 was recorded 2 km north-northeast of Reno, Nevada. The sequence began at 14:09 on 29 December 2023 and concluded at 13:42 on 3 January 2024, spanning 119 hours and 33 minutes. During this period, 117 earthquakes were detected.
Analysis of the first 100 events reveals predominantly shallow focal depths between 2 km and 7 km, with the majority clustered around 4–6 km. Magnitudes ranged from –0.4 to 1.9, indicating low-energy release consistent with swarm behavior rather than a mainshock-aftershock sequence. The largest events (magnitudes 1.9, 1.8, 1.7, and 1.6) occurred between 31 December 2023 at 05:34 and 06:33, all at depths of 5–6 km. Smaller events (magnitudes below 0.5) were frequent, reflecting ongoing microseismicity within a localized fault network.
Reno lies within the western Basin and Range Province, an extensional tectonic regime characterized by north-south trending normal faults and distributed deformation. The region experiences frequent earthquake swarms due to interaction between Walker Lane shear and Basin and Range extension. Historical records since 2000 document 37 swarms in the immediate area, with notable clusters in 2008 (7 swarms), 2013 (8 swarms), and 2014 (5 swarms). These episodes typically involve hundreds of small events over days to weeks and are linked to fluid migration or aseismic slip on shallow faults.
The December 2023–January 2024 swarm aligns with this established pattern, showing no evidence of escalation toward a larger mainshock. Depths and magnitudes remain typical for background swarm activity in the Reno basin, where Quaternary faults accommodate regional extension at rates of approximately 1 mm per year.
References
- SeismoSight internal swarm catalog S20231230.1
- USGS Earthquake Hazards Program – Nevada seismicity summaries
- Nevada Bureau of Mines and Geology – Basin and Range tectonic framework (updated 2023)