Images

Landsat-8 nighttime thermal infrared image from April 2017 showing the Tern Lake area. In Yellowstone, temperatures are extremely cold at night in the winter, and most lakes are frozen (dark pixels). West Tern Lake seems to be thawing here - perhaps it receives some thermal waters from nearby hot springs.

Map of thermal areas in Yellowstone National Park. Most of Yellowstone's more than 10,000 thermal features are clustered together into about 120 distinct thermal areas (shown in red). Lakes are blue. The Yellowstone Caldera is solid black and the resurgent domes are dotted black. Roads are yellow.

Native sulfur crystals precipitate at Sulphur Banks via a chemical reaction between different sulfur-bearing volcanic gases. USGS image by P. Nadeau.

HVO gas geochemists periodically collect gas samples at Sulphur Banks, near the Kīlauea Visitor Center, in Hawai‘i Volcanoes National Park. Samples are analyzed for bulk chemistry and for helium isotopes. The results are compared to previous measurements to evaluate potential changes in activity at the volcano.

An HVO geologist removes the sampling tube following the gas collection. Inserting the tube down into the degassing source limits contamination of the volcanic gas sample by atmospheric gases. USGS image by P. Nadeau.

NASA Yellowstone astrobiology expedition team members stand in front of Great Fountain Geyser after completion of field work, February 28, 2019. Research conducted under Yellowstone Research Permit YELL-2019-SCI-8094.

COSMO-SkyMed (CSK) Interferogram for the period from April 6 to June 2, 2019, covering Kīlauea Volcano's summit region. Each color fringe represents 1.65 centimeters (0.65 inches) of ground displacement.

Montana State University students at an outcrop along Highway 20, in Idaho, sampling the Mesa Falls Tuff fall deposit exposed just beneath the ignimbrite. Photo by Madison Myers (Montana State University) on June 9, 2019.

Magma dynamics experiments seek to recreate the pressure and temperature at depths far beneath a volcano, in order to determine how the magma forms, evolves, and ascends prior to eruption.

Areas on Kīlauea that will be covered by a helicopter lidar survey in June 2019. Red lines enclose areas over which the survey helicopter will fly at 396 m (1,300 ft) above ground level. Green lines enclose areas over which the helicopter will fly at 151 m (500 ft) above ground level. USGS map.

Map showing the three types of young faults in Yellowstone National Park. Courtesy of the Wyoming State Geological Survey.

Schematic illustration showing the inferred irregular conduit geometries of (a) Old Faithful geyser, in Yellowstone National Park; (b) Velikan geyser, in Kamchatka, Russia, with boulders at the bottom depicted in brown; and (c) Geysir, in Iceland. The walls of the conduits are lined with white silica sinter similar to that exposed on the surface.

Schematic illustration showing the inferred subsurface structure of Geyser Flat, Whakarewarewa, in the Taupo Volcanic Zone, New Zealand. From manuscript by Hurwitz and Manga (Annual Review of Earth and Planetary Sciences, 2017. Vol. 45, pp. 31–59).

USGS geologists are conducting field work at the summit today to make observations of volcanic ash and measure volcanic gas. This photograph is taken on Crater Rim Drive where the road intersects the Southwest Rift Zone. Rockfall dust and volcanic ash covers the ground and cracks in line with the Southwest Rift Zone trace traverse the pavement.

Geologic time scale showing the geologic eons, eras, periods, epochs, and associated ages in millions of years ago (MYA). The time scale also shows major evolutionary and tectonic events in North America.

Map showing the northwestern corner of the Sour Creek Dome. The red lines mark the area where the map will be changing to become more accurate. Figure adapted from Wilson et al. 2018 (Bulletin of Volcanology, v. 80, article 53; doi:10.1007/s00445-018-1229-x).

A section of the Porcelain Basin Loop boardwalk in the Norris Geyser Basin was removed because the ground below sections of the boardwalk became too hot and made charcoal of the wood footings that support the structure. Luckily enough in this case, the boardwalk was shifted about 3 feet to avoid the new hot ground.

These views of Mauna Loa are from near the Hawaiian Volcano Observatory looking toward the west. The view on left is typical during strong trade winds that blow the plume from Halema‘uma‘u Crater southwest of the summit area. The view on right is common during slack winds that allow vog conditions to develop in the summit area of Kīlauea.

Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera. The resurgent dome, Doe Ridge, Mammoth Mountain, and the Inyo Craters and Domes all reflect volcanic activity since 760,000 years ago, when a giant eruption formed the caldera.

Clear day view of Mauna Loa during tradewind conditions from the summit of Kīlauea Volcano.

Map showing the locations of all U.S. volcanoes with their threat category designated by color. Very high threat is red, high is orange, moderate is yellow, low is green, and very low is blue.