Images

Map of Geyser Hill, Upper Geyser Basin, Yellowstone National Park, showing selected thermal features, including new and reactivated features that were active during the May-June 2023 thermal unrest.  Map prepared by by Kiernan Folz-Donahue, Yellowstone National Park.

Hydrothermal explosion crater that has existed since at least 1954 located just southwest of The Gap in Norris Geyser Basin, Yellowstone National Park. Photo taken in June 2023 by Lauren Harrison.

A garter snake along Violet Creek near the Mary Mountain Trail in Hayden Valley, Yellowstone National Park. This snake used the geothermally warmed creek to thermoregulate during near-freezing overnight conditions. USGS photo by Stanley Mordensky, June 2023.

Panoramic view of the Pocket Basin hydrothermal explosion crater located in Lower Geyser Basin, Yellowstone National Park. The crater is approximately 365 by 800 meters (1200 by 2600 feet) and formed about 13,900 years ago, at the end of the most recent ice age.

A garter snake along Violet Creek near the Mary Mountain Trail in Hayden Valley, Yellowstone National Park. This snake used the geothermally warmed creek to thermoregulate during near-freezing overnight conditions. USGS photo by Stanley Mordensky, June 2023.

Map of continuous Global Positioning System (GPS), semipermanent GPS, borehole strainmeters, and borehole tiltmeters that provide surface deformation monitoring capability in and around Yellowstone National Park. Red line denotes boundary of Yellowstone Caldera.

Thermal feature UNNG-GHG-17a, not far from Sponge Geyser on Geyser Hill in Upper Geyser Basin, Yellowstone National Park.  The feature formed during a period of thermal unrest that began in May 2023 and threw debris and hot water onto the adjacent boardwalk, which was closed for safety.  National Park Service photo by Kiernan Folz-Donahue, May 31, 2023.

Borehole station B945, near Panther Meadow between Mammoth Hot Springs and Norris Geyser Basin in Yellowstone National Park.  Left (“before”) panel shows old VSAT satellite communication network, with a large, round antenna (photo by Scott Johnson, EarthScope Consortium, on May 13, 2022).  Right (“after”) panel shows the station with a new Starlink antenna

Distribution of hydrothermal features in Yellowstone as a function of their pH (modified and updated from Nordstrom et al., 2009). There are two distinct groupings: one is more acidic, and the other neutral to basic.

Front cover of the Yellowstone Volcano Observatory 2022 annual report, which includes a summary of earthquake, deformation, and geyser activity, as well as research investigations and other information.

Soil carbon dioxide concentration and temperature measured at a new thermal area near Tern Lake in Yellowstone National Park on the east side of Yellowstone Caldera. A, Map of soil carbon dioxide flux simulated based on measurements made at the black dots in September 2022. B, Map of soil temperature at a depth of 20 centimeters (8 inches).

Simplified map of the Wyoming Province—a craton composed of Archean-age continental crust. Archean- and Proterozoic-age rocks outcrop in many places within the Wyoming Province and are shown as dark grey blobs. The yellow blob highlights the location of the Hellroaring and Crevice plutons, a small portion of which are exposed in northern Yellowstone National Park.

WorldView-2 natural-color satellite image from February 3, 2023, showing snow-free zones around Twin Buttes, just beyond the southwest portion of Lower Geyser Basin.   At the time and date this image was acquired, there was extensive

Map of the distribution of pH for thermal pools within Norris Geyser Basin, Yellowstone National Park.  Cool colors are acidic, and warm colors are neutral to slightly basic.  These data were collected and organized using Geographic Information System (GIS) tools. Map by Jefferson Hungerford and Kiernan Folz-Donahue, Yellowstone National Park.

Volcanic deposits associated with the Absaroka volcanic province along the eastern and northern boundaries of Yellowstone National Park. The left panel shows the spread of the Absaroka Volcanic Supergroup (AVS) throughout Wyoming and Montana.

Isotopic composition of the primary volcanic groups of the Absaroka volcanic province (the Washburn, Sunlight, and Thorofare groups) and two volcaniclastic units, the Sepulcher formation and the Daly formation.

Landsat 8 nighttime thermal infrared image of Yellowstone National Park from January 31, 2023. Satellite-based thermal infrared data show areas on the surface that are warmer versus cooler, and they can be used to estimate surface temperature and the geothermal radiative heat output from the Yellowstone magmatic and hydrothermal system.

Geology of the unconformity on Mount Everts in Yellowstone National Park.  Sketch at the top was made by geologist William Henry Holmes in 1878 and correctly identifies Cretaceous sediments overlain by much younger rhyolite rocks, including fine ash deposits (“tufa”).  The photo at the bottom shows the same outcrop as viewed from Mammoth Hot Springs (USGS

An example of the repeating seiche—a long-period oscillatory wave that can be present on a lake—measured over the course of a day by the lake-level sensor at the Grant Village boat dock on the West Thumb of Yellowstone Lake. The plot shows a cyclic variation of about 2 centimeters that occurs numerous times during June 13, 2021.

Map of Yellowstone National Park lakes, rivers, and streams, with colors indicating the amount of arsenic in the water.  The Maximum Contaminant Level (MCL) defined by the Environmental Protection Agency for arsenic in drinking water is 10 micrograms per liter (µg/L).  In the vicinity of major geyser basins, especially on the Firehole and Madison Rivers, a

Pie diagram showing the chloride flux, in kilotons per year (kt/yr), measured in 2022, with percentages for the four major rivers (Madison, Yellowstone, Snake, and Falls rivers) that drain Yellowstone National Park. Figure developed by Baine McCleskey.