Seismic Swarm SVS20240104.1: Analysis of Activity Near West Yellowstone

Seismic swarm SVS20240104.1 occurred 29 km east-southeast of West Yellowstone, Montana, within the Yellowstone volcanic region. The sequence began at 19:37 on 3 January 2024 and concluded at 11:12 on 5 January 2024, spanning 39 hours and 35 minutes. During this interval, 62 earthquakes were recorded, with magnitudes ranging from -0.1 to 3.2 and focal depths predominantly between 2 km and 16 km.

The swarm initiated with several events near magnitude 0.0 at depths of 9 km. Activity intensified shortly after midnight on 4 January, including a magnitude 3.2 earthquake at 10 km depth followed by a magnitude 2.1 event at 2 km. Subsequent events remained mostly below magnitude 2.0, with the majority clustered between 7 km and 10 km depth. Later phases on 4 and 5 January featured smaller events, concluding with low-magnitude activity at shallower depths around 3–7 km.

This pattern aligns with typical swarm behavior in the region, characterized by a rapid onset of numerous small-magnitude events without a single dominant mainshock. Depths indicate activity within the brittle upper crust overlying the Yellowstone magmatic system.

The Yellowstone area lies atop an active volcanic caldera formed by massive eruptions over the past 2.1 million years. Ongoing crustal deformation, hydrothermal fluid movement, and minor magma intrusions drive frequent seismicity. Earthquake swarms have been documented here for decades, often linked to these subsurface processes rather than tectonic faulting alone.

Historical records show 88 swarms in the region since 1 January 2000. Annual counts include peaks of 10 swarms in 2022 and 7 each in 2000 and 2008, with lower activity in several intervening years. The 2024 swarm represents the first recorded that year, continuing a long-term pattern of episodic clustered seismicity.

Such events provide valuable data on the dynamics of the Yellowstone Plateau, where seismic monitoring supports hazard assessment for the surrounding region.

References

USGS Earthquake Hazards Program – Yellowstone seismicity reports
Montana Bureau of Mines and Geology – Regional seismic catalogs
Yellowstone Volcano Observatory – Geological background on the caldera system