Volcano Updates

Alert Level: NORMAL, Color Code: GREEN 2021-07-01 11:47:21

YELLOWSTONE VOLCANO OBSERVATORY MONTHLY UPDATE
U.S. Geological Survey
Thursday, July 1, 2021, 5:47 AM MDT (Thursday, July 1, 2021, 11:47 UTC)


YELLOWSTONE VOLCANO (VNUM #325010)
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

For the first time since April 2018, before its current cycle of frequent eruptions, Steamboat Geyser did not experience any eruptions during a calendar month. Over the past few months, the time between eruptions has been increasing, instead of decreasing as has been the case during the summers of 2018, 2019, and 2020. This may indicate that the present period of frequent eruptions is coming to a gradual close, although current minor eruptions at the geyser suggest that the period of major eruptions is not yet completely over. The total number of eruptions for the year remains at 12.

June field work by Yellowstone Volcano Observatory scientists included the deployment of 140 temporary seismic stations by the University of Utah in Norris Geyser Basin. The project builds on previous experiments in 2018 and 2019, covering a broader area that will allow seismologists to “see” deeper beneath the surface. The work aims to better understand the connection between Steamboat Geyser and Cistern Spring, as well as more general patterns of subsurface water flow at Norris Geyser Basin. In addition, two semi-permanent GPS stations were set up, near Mount Washburn and Mary Mountain, bringing the number of deployed semi-permanent GPS stations to 17. These stations are installed every spring and recovered in the fall, operating during the period of largely snow-free conditions, and they serve to augment the network of continuous GPS stations, which operate year-round.

Seismicity

During June 2021, the University of Utah Seismograph Stations, responsible for the operation and analysis of the Yellowstone Seismic Network, located 445 earthquakes in the Yellowstone National Park region. While above average for a month, this is by no means unprecedented. For example, over 1100 earthquakes were recorded during the month of June 2017! The largest event of the past month was a minor earthquake of magnitude 3.1 located 11 miles northeast of West Yellowstone, MT, on June 28 at 8:29 AM MDT. This event is part of a sequence of earthquakes in the same area that began on June 19.

June seismicity in Yellowstone was marked by four earthquake swarms:

1) A swarm of 153 earthquakes, ~11 miles northeast of West Yellowstone, MT, began June 19. It includes the largest event of the month on June 28, as well as six earthquakes in the magnitude-2 range.

2) Another swarm of 153 earthquakes, ~10 miles north-northeast of Old Faithful, Yellowstone National Park, began on June 9, with most of the seismicity occurring on June 21. The largest earthquake of the swarm (magnitude 2.5) occurred June 21 at 11:20 AM MDT. This swarm includes 12 earthquakes in the magnitude 2 range.

3) A swarm of 52 earthquakes, ~7 miles north-northeast of West Yellowstone, MT, began June 29, with the largest event (magnitude 1.6) occurring on June 29 at 02:38 PM MDT.

4) A small swarm of 18 earthquakes, ~7 miles north of West Yellowstone, MT, began June 22, with the largest earthquake (magnitude 1.4) occurring June 22 at 04:26 AM MDT.

Earthquake sequences like these are common and account for roughly 50% of the total seismicity in the Yellowstone region.

Yellowstone earthquake activity is currently above background levels.

Ground deformation

Subsidence of Yellowstone Caldera, which has been ongoing since 2015, slowed during May/June 2021, reflecting seasonal groundwater recharge. Every summer, water from snowmelt causes the ground to swell slightly, resulting in a pause in subsidence trends or even a minor amount of uplift (less than 1 cm / fraction of an inch). In the area of Norris Geyser Basin, no significant uplift or subsidence has been detected by a nearby GPS station since the start of 2020.

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, UNAVCO, Inc., Wyoming State Geological Survey, Montana Bureau of Mines and Geology, Idaho Geological Survey



CONTACT INFORMATION:

Michael Poland, Scientist-in-Charge
mpoland@usgs.gov