Hazard Notification System (HANS) for Volcanoes


U.S. Geological Survey
Friday, December 1, 2023, 9:20 AM MST (Friday, December 1, 2023, 16:20 UTC)

44°25'48" N 110°40'12" W, Summit Elevation 9203 ft (2805 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

Recent Work and News

Steamboat Geyser erupted on November 13—its 8th major water eruption of 2023. Since that time, the geyser has been quiet, with no minor eruptions.

Most roads in Yellowstone National Park are currently closed to prepare for the winter season and snowmobile and snowcoach travel, which will begin on December 15.  The road between the North Entrance and the Northeast Entrance is open to regular vehicles year-round.


During November 2023, the University of Utah Seismograph Stations, responsible for the operation and analysis of the Yellowstone Seismic Network, located 119 earthquakes in the Yellowstone National Park region. The largest event of the month was a minor earthquake of magnitude 2.8 located about 15 miles southeast of Mammoth, Wyoming, on November 10 at 10:16 PM MST.  

November seismicity in Yellowstone was marked by two swarms:

1. A swarm of 27 earthquakes, located approximately 3 miles southeast of West Yellowstone, MT, occurred during November 19–30. The largest earthquake in the sequence was a magnitude 1.2 event on November 22 at 5:07 AM MST.

2. A swarm of 26 earthquakes, located approximately 11 miles south-southwest of West Thumb, WY, occurred during November 6–12, with the largest event of the sequence being a micro earthquake of magnitude 2.5 on November 6 at 8:42 AM MST.

Yellowstone earthquake activity is currently at background levels.


Ground Deformation

During the month of November, continuous GPS stations in Yellowstone caldera showed subsidence, which has been ongoing since 2015, interrupted in summer months by a pause or slight uplift caused by groundwater accumulation from snowmelt and runoff.  Approximately 1.2 cm (0.5 in) of subsidence has occurred in the caldera since the end of September.  Deformation at Norris Geyser Basin is following the same trend as the caldera, but with slightly lower magnitudes of change.

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

The Yellowstone Volcano Observatory (YVO) provides long-term monitoring of volcanic and earthquake activity in the Yellowstone National Park region. Yellowstone is the site of the largest and most diverse collection of natural thermal features in the world and the first National Park. YVO is one of the five USGS Volcano Observatories that monitor volcanoes within the United States for science and public safety.

YVO Member agencies: USGS, Yellowstone National Park, University of Utah, University of Wyoming, Montana State University, Earthscope Consortium, Wyoming State Geological Survey, Montana Bureau of Mines and Geology, Idaho Geological Survey


Michael Poland, Scientist-in-Charge