Images

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.

Microscope thin-section photo of Lava Creek Tuff “unit 2.” Photo by Ray Salazar (Montana State University) on October 28, 2021.

Example initial analyses on the water temperature data. (a, c) Graphs showing the calculated time between eruptions. (b, d) Histograms demonstrating the distribution of eruption intervals.

Yellowstone Lake bathymetry showing the location of the Deep Hole vent field.  Inset shows locations of heat-flux measurements (red dots) in the Deep Hole vent field.

Research Vessel Annie and Remotely Operated Vehicle Yogi.  a) R/V Annie on Yellowstone Lake operated by the Global Foundation for Ocean Exploration.  Image Rob Harris, OSU.  b) ROV Yogi with GFOE President Dave Lovalvo.  Image Todd Gregory, GFOE.  C) ROV Yogi and 1-m heat flow probe.  This pr

Different views of an eruption from two predictable geysers. (a, c) Graphs showing water temperatures recorded by data loggers stationed near Beehive and Old Faithful Geysers, respectively. These data loggers were deployed by the Yellowstone Geology Program, configured to capture temperatures at one-minute intervals (indicated by blue dots).

USGS Earth Explorer screen shot showing example of selecting the Data Sets to search.

USGS Earth Explorer screen shot showing example of Landsat 8 search results over Yellowstone.

Screen shot of the USGS Earth Explorer web tool showing an example of the geographic area and date range search criteria for Yellowstone.

Site of the former Fountain Hotel in Yellowstone National Park.  Red arrows indicate the location of the pipe that ran through the meadow between Leather Pool and the site of the Fountain Hotel (yellow arrow). Yellowstone National Park photo by Annie Carlson, October 2021.

Shaded relief map of Henrys Fork Caldera and vicinity. The margin of Henrys Fork Caldera is shown in blue. Note the smooth, low-relief topography within the caldera compared to the steep and dynamic topography associated with Yellowstone Caldera (at the right side of the image).

Interferogram created from data collected on September 22, 2020, and September 17, 2021, by the Sentinel-1 satellite system. Colored fringes indicate a change in distance (called range change) between the satellite and ground surface that is caused by surface deformation.

Pore waters from Yellowstone Lake sediment cores collected in August 2021 are extracted through filtration devices into plastic syringes.  Note that the second core from the left appears light in color because the plastic core liner was etched by very hot 91°C (196°F) fluids.

Gravity coring device on the rear deck of the R/V Annie after coring the floor of Yellowstone Lake, with dark mud coating the outside of the corer.  The 100-lb. green coring head is at the top, and the bottom of the barrel has a tapered stainless steel core cutter.

View to the aft of the R/V Annie as it leaves Bridge Bay Marina early in the morning of August 26, 2021.

A hand-sample photo of what is known to be Lava Creek Tuff “unit 2.”  Small black scoria pieces are distinctive of this unit compared to the previously recognized Member A and Member B of the Lava Creek Tuff.  Photo by Ray Salazar (Montana State University) on August 16, 2021.

Schematic displaying the general processes associated with collapse of Yellowstone Caldera.  (A) Pre-caldera volcanism includes the eruption of dome complexes from the underlying magma chambers.  (B) The caldera-forming eruption evacuates a significant amount of magma from the chamber, causing the overlying crustal block to subside into the void space.&nbs

“Hey Bear” volcano, Wyoming, with Raggedtop Mountain in the background. Hey Bear volcano is a small scoria cone that is about 1.3 million years old and that erupted over Eocene (~50 million-year-old) rocks (noted by yellow dotted line). Photo by Matthew Brueseke, Kansas State University, August 2021, used with permission.

Photograph of Twin Buttes in Lower Geyser Basin looking to the northwest, with Excelsior Geyser of Midway Geyser Basin in the foreground. Twin Buttes is a thermal kame that formed when glaciers covered the area, and hydrothermal activity below the ice led to melting and the deposition and cementation of glacial sediments.

The Yellowstone borehole geophysical network, installed by UNAVCO in 2007–2008. The placement of the boreholes is focused primarily around the caldera, and the boreholes contain a mix of instruments, including strainmeters, seismometers, tiltmeters, and pore pressure sensors.