USGS Volcano Notice - DOI-USGS-YVO-2026-05-01T20:15:28+00:00

Summary

Yellowstone Caldera activity remains at background levels, with 97 located earthquakes in April (largest = M2.5). Deformation measurements indicate no significant uplift or subsidence of the caldera or north caldera rim since January 2026.

Recent Work and News

Echinus Geyser, in Norris Geyser Basin, reawakened from a several-year slumber in February, with about 40 eruptions that month, but the geyser had only four eruptions in April.  At Black Diamond Pool in Biscuit Basin (site of a hydrothermal explosion in 2024), two eruptions were recorded during the month by acoustic, seismic, and temperature measurements, occurring on April 28 and 29.  The latter event was the largest recorded since monitoring instruments were installed in the area during summer 2025.  In April, geologists visited the park to conduct field investigations of geyser activity.  Planned field work in May includes deployment of ground deformation equipment, geochemical sampling, and reconnaissance work for new monitoring stations.  The biennial Yellowstone Volcano Observatory coordination meeting will also take place in May.

Seismicity

During April 2026, the University of Utah Seismograph Stations, responsible for the operation and analysis of the Yellowstone Seismic Network, located 97 earthquakes in the Yellowstone National Park region. The largest event of the month was a microearthquake of magnitude 2.5 located about 16 miles south-southeast of Mammoth Hot Springs in Yellowstone National Park on April 14 at 2:13 a.m. MDT.

April seismicity in Yellowstone was marked by a swarm of 16 earthquakes that occurred approximately 16 miles south-southeast of Mammoth Hot Springs in Yellowstone National Park during April 13–14. The largest earthquake in the sequence was also the largest in April (described above).

Earthquake activity in Yellowstone is at background levels.

Ground Deformation

Continuous GPS stations indicate that the uplift that started in July 2025 on the north caldera rim ceased by mid-January 2026.  In Yellowstone Caldera, continuous GPS data recorded little net change since December.  This is the first winter since 2015–2016 with no caldera subsidence, suggesting a subtle change in the style of caldera deformation.

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