USGS Volcano Notice - DOI-USGS-YVO-2025-11-03T19:54:44+00:00

Summary

Yellowstone Caldera activity remains at background levels, with 180 located earthquakes in October (largest = M3.7). Deformation measurements indicate that the annual summertime pause in long-term caldera subsidence has ended, and subsidence has resumed.

Recent Work and News

Minor eruptions of Steamboat Geyser in Norris Geyser Basin remain sporadic, indicating that a major eruption is unlikely anytime soon.  There have only been 2 major eruptions of the geyser so far during 2025, and the period of frequent activity that started in 2018 has probably ended.  Valentine and Guardian Geysers in Norris Geyser Basin continued intermit eruptions through mid-October.

Seismicity

During October 2025, the University of Utah Seismograph Stations, responsible for the operation and analysis of the Yellowstone Seismic Network, located 180 earthquakes in the Yellowstone National Park region. The largest event of the month was a minor earthquake of magnitude 3.7 located about 14 miles south-southwest of Mammoth Hot Springs in Yellowstone National Park on October 28 at 7:22 a.m. MDT.

October seismicity in Yellowstone was marked by four swarms:

1. A swarm that started approximately 14 miles south-southwest of Mammoth Hot Springs in Yellowstone National Park in late September continued with ongoing seismicity in early to mid October, adding 15 earthquakes to the sequence. The largest earthquake of the swarm during October was a magnitude 1.7 on October 8 at 10:06 p.m. MDT.

2. A swarm of 23 earthquakes took place approximately 4 miles southwest of West Thumb, in Yellowstone National Park, on October 15. The largest earthquake in the sequence was a magnitude 1.9 on October 15 at 4:15 a.m. MDT.

3. A swarm of 12 earthquakes occurred approximately 6 miles north of West Yellowstone, Montana, during October 28–30. The largest earthquake in the sequence was a magnitude 2.0 on October 29 at 1:25 a.m. MDT.

4. A second swarm of 42 earthquakes in the region of swarm #1 (above), approximately 14 miles south-southwest of Mammoth Hot Springs in Yellowstone National Park, took pace during October 28–31. The largest swarm earthquake is also the largest of October (described above).

Earthquake activity in Yellowstone remains at background levels.

Ground Deformation

Continuous GPS stations in Yellowstone Caldera recorded the end of the seasonal deformation signal, which is related to snowmelt and groundwater conditions.  Starting in mid-October, the summertime pause in subsidence or slight uplift ended, and long-term subsidence, which has been ongoing since 2015, resumed.  Deformation in the area of Norris Geyser Basin also recorded the end of the seasonal uplift signal.

An example of GPS data can be found at http://www.unavco.org/instrumentation/networks/status/pbo/data/NRWY (click on Static Plots / Cleaned)