A seismic swarm designated S20190414.1 occurred approximately 30 km west of Kanosh, Utah, beginning at 23:17 on 13 April 2019 and concluding at 07:10 on 14 April 2019. Over 7 hours and 53 minutes, 28 earthquakes were recorded. The events clustered tightly in both time and space, with magnitudes ranging from 0.6 to 4.0 and depths mostly between 0 and 14 km.
The sequence initiated with two magnitude-1.9 events at 23:17 and 23:45 on 13 April. Activity intensified after midnight, culminating in the largest event—a magnitude-4.0 earthquake at 03:59 on 14 April at 1 km depth. This was followed within minutes by a magnitude-3.1 shock. Subsequent events included multiple magnitude-2+ quakes interspersed with smaller tremors, tapering off by early morning. Notable later events comprised a magnitude-2.6 at 04:09 and a magnitude-1.9 at 06:33, both at shallow depths.
The region lies in the Basin and Range Province of central Utah, where east-west crustal extension drives normal faulting along north-south trending structures. This tectonic setting produces frequent small-to-moderate earthquakes and occasional swarms. The area west of Kanosh sits near the Sevier Desert and Black Rock Desert fault systems, part of the broader Intermountain Seismic Belt. Updated geological mapping confirms ongoing extension rates of several millimeters per year, consistent with GPS measurements across the province.
Historical records indicate limited swarm activity in the immediate vicinity since 2000, with only two prior swarms documented—one in 2000 and one in 2001. These earlier episodes similarly featured shallow events, underscoring the episodic nature of seismicity in this portion of the Basin and Range.
The 2019 swarm's shallow focal depths and rapid succession of events align with fluid-driven or stress-transfer mechanisms commonly observed in extensional regimes. No damage or felt reports beyond the immediate area were associated with the magnitude-4.0 mainshock, reflecting the modest energy release typical of such sequences.