Images

Signals recorded at station YDD in Yellowstone National Park from the 2022 Hunga Tonga–Hunga Haʻapai volcanic eruption. The seismometer at YDD recorded both the direct seismic phase (top left) as well as the atmospheric Lamb Wave that coupled to the ground as it propagated (top right).  The infrasound microphone at YDD recorded the atmospheric disturbance

Time series showing daily vertical GPS positions from the continuous GPS station HUSB between 2001 and 2022.

Comparison of vertical GPS motion measured at station HUSB (top) with earthquake depth (bottom). Red line is a 60-day average of the cleaned GPS time series plotted in gray. Earthquakes are plotted with respect to their magnitudes. The swarm in 2004 represents the vast majority of earthquake in the vicinity of the deforming region.

Map of seismicity (red circles) in the Yellowstone region during 2021. Gray lines are roads, black dashed line shows the caldera boundary, Yellowstone National Park is outlined by black dot-dashed line, and gray dashed lines denote state boundaries.

Scarp of the Uhl Hill fault. Photo (top) is looking west at the east-facing fault scarp, with a geologist at the top of the scarp for scale. Here, the fault cuts through Pinedale-1 glacial deposits just south of a Pinedale-2 end moraine. Plot (bottom) is a scarp profile generated from lidar elevation data.

Logs and debris removed from Solitary Geyser, near Old Faithful, during remediation work in 2021.  Photo by Jeff Cross.

Satellite radar interferogram spanning June 19, 2020, to August 13, 2021, and showing the ground motion in the direction of the satellite.

Boiling River near Mammoth Hot Springs, Yellowstone National Park.  Photo by R. Robinson.

Left photo shows a loose piece of siliceous sinter that was precipitated around a photosynthetic microbial mat in the Lower Geyser Basin.  The microbial mat died when the outflow channel changed positions.

Simplified geologic maps showing the difference in mapped rock units from the current, large-scale geologic maps dividing Mount Everts and that join along the boundary between Montana and Wyoming.

Map of the Uhl Hill fault in eastern Grand Teton National Park. Base map is a 1-meter lidar hillshade. Black arrows mark the visible fault scarp, and red lines mark locations where scarp profiles were generated from lidar data or field surveying.

On the left is Castle Geyser during an eruption with a pool from nearby Tortoise Shell Spring showing photosynthetic pigments at the bottom. The middle image is of a small pool in the Geyser Hill Group in the Upper Geyser Basin with an outflow channel full of yellow, green, orange, red, and brown pigmented phototrophic microbial mats.

A 200-kilogram (440-pound) fragment of the Canyon Diablo meteorite that was found at Meteor Crater in Arizona.

Reconstructed fossil horse skeleton found at Hagerman Fossil Beds National Monument, Idaho. National Park Service photo, https://www.nps.gov/articles/000/equus_simplicidens.htm.

Michelle Coombs is a volcanologist with the U.S. Geological Survey Volcano Hazards Program. She works out of the Alaska Science Center in Anchorage, Alaska.

Cumulative number of aftershocks greater than magnitude 2.5 following the March 30, 2020, magnitude-6.5 Stanley earthquake in central Idaho. The black line shows the observed aftershocks, the red line shows the predicted number of aftershocks. Aftershocks are a normal and expected phenomenon following strong tectonic earthquakes.

Regional map of southeastern Idaho showing the relative location of Yellowstone National Park and the Stanley earthquake aftershocks. Yellowstone National Park (outlined in yellow) is at least 275 km away from the 2020 M_w6.5 Stanley earthquake. Several active faults (in red) are located between the Stanley earthquake and Yellowstone Caldera.

A branching root cast from grasses that grew on the ashy lahars deposited along the ancestral Missouri River system. Plant roots growing in calcareous soils made holes that were filled with calcite after the organics rotted away.  Photo by Rob Thomas, August 2021.

Comparison of (a) 1904 Historical map with (b) 1988 USGS map. Colloidal Pool is a large, labeled pool roughly located on a straight line between Hurricane vent and Whirligig Geyser on the 1988 map (b); this same transect on the 1904 map (a) shows no feature at that location (white circle).

Scanning electron microscopy (SEM) images of the Colloidal Pool colloids (images are a combination of backscatter and secondary electrons). The colloids are a mixture of clay particles, hydrated silica, alunite, and diatoms.

A view of White Mountain -- a deposit of the Heart Mountain detachment -- from the Sunlight Basin Road in Wyoming. Much of the evidence supporting the lamprophyre diatreme triggering mechanism theory for the landslide was gathered at White Mountain.