Seismic Swarm S20080314.1: Analysis of Activity Near Mogul, Nevada

The seismic swarm designated S20080314.1 occurred 0 km northeast of Mogul, Nevada, beginning at 00:02 on 14 March 2008 and concluding at 23:07 on 9 April 2008. Over 647 hours and 4 minutes, the sequence produced 841 earthquakes. This event represents the sixth swarm recorded in the region since 1 January 2000, following earlier episodes in 2003 (1 swarm), 2004 (2 swarms), 2005 (2 swarms), and the current 2008 sequence.

Examination of the first 100 events reveals predominantly low-magnitude activity consistent with swarm behavior rather than a mainshock-aftershock pattern. Magnitudes ranged from -0.9 to 2.6, with the majority falling between 0.0 and 0.8. Depths were shallow, concentrated between 0 and 7 km, though isolated events reached 9 km and 14 km. Early activity on 14 March featured events such as a magnitude 0.5 at 6 km depth at 00:02:57, followed by a magnitude 1.2 at 5 km at 02:46:24. Subsequent hours showed clusters of micro-earthquakes, including multiple magnitude 0.3–0.7 events at depths of 2–7 km. By 15 March, a magnitude 2.6 event at 0 km depth at 15:38:35 marked the strongest in the initial phase, accompanied by several magnitude 1.0–1.4 shocks at depths of 1–2 km. Later events through 18 March continued the pattern of shallow, low-magnitude occurrences, with many registering at or below magnitude 0.5 and depths under 5 km.

Mogul lies within the western Basin and Range Province, a region defined by active extensional tectonics driven by normal faulting and right-lateral shear. The locale forms part of the Walker Lane belt, where northwest-directed Pacific-North America plate motion produces distributed deformation across a network of faults. This tectonic setting accounts for the recurrent swarms, as fluid migration and stress transfer along shallow crustal faults trigger episodic clusters without a dominant mainshock. Historical patterns since 2000 indicate that such swarms recur every few years, typically lasting weeks and producing hundreds of events of similar magnitude and depth distributions.

The 2008 swarm aligns with this regional framework, underscoring the persistent seismic hazard in the Reno-Mogul area. Continued monitoring remains essential given the shallow source depths that can amplify ground motion in nearby populated zones.

References
SeismoSight internal swarm classification records.
USGS Earthquake Catalog for Nevada regional tectonics.
Nevada Seismological Laboratory historical swarm documentation.