Images

Woody debris forms an upstream dam in the 2024 Elk Fire burn area near Dayton, Wyoming. The dam was deposited by a debris flow triggered during a 2025 summer thunderstorm. The woody debris forming the dam is larger and more abundant than material observed lower in the channel.

Burned watershed in the 2024 Elk Fire burn area where a debris flow was triggered during a July 2025 thunderstorm. This downstream view shows the watershed outlet near the Crystal Springs Rest Area and U.S. Highway 14. Heavy equipment used to clear the debris remains on site 8 days after the event.

Postfire debris-flow levee in the 2024 Elk fire burn area near Dayton, Wyoming. This levee, located near the channel margin contains poorly sorted sediment ranging from fine mud-to boulder-sized. A small amount of woody material is also present in the levee. The levee was formed by a debris flow in the watershed, triggered by a 2025 summer thunderstorm.

Close-up view of a debris-flow deposit in the 2024 Elk Fire burn area near Dayton, Wyoming. A debris flow triggered by a 2025 summer thunderstorm deposited poorly sorted material ranging from mud to boulder size. Mud coatings are observed on some larger rocks, and finer material fills spaces between the cobbles and boulders.

Channel in a burned watershed within the 2024 Elk Fire burn area near Dayton, Wyoming where a debris flow initiated during a July 2025 thunderstorm. Near the headwaters, exposed bedrock is visible in channel, and loose sediment and burned trees cover the hillslope above. Trees near the channel margin show damage from the force of the flow.

USGS Postfire landslide monitoring station in the 2024 Elk Fire burn area near Dayton, Wyoming. The station records rainfall and soil moisture data and captured video of a debris flow on July 15, 2025. The channel where the flow occurred is visible in the background.

Debris-flow deposit in the 2024 Elk Fire burn area. The flow partially covered U.S. Highway 14 west of Dayton, Wyoming. Sediment and woody debris partially covered U.S. Highway 14, near the Crystals Springs Rest Area after a thunderstorm triggered a debris flow in a burned watershed.

Postfire debris-flow deposit in a channel within the 2024 Elk Fire burn area near Dayton, Wyoming. Following a July 2025 thunderstorm, the channel filled with mud, cobbles, small boulders, and woody debris. This photo, taken near the watershed outlet, looks upslope from U.S. Highway 14.

Postfire debris-flow deposit in a channel within the 2024 Elk Fire burn area near Dayton, Wyoming. Following a July 2025 thunderstorm, the channel filled with mud, cobbles, small boulders, and woody debris. The material shown here is finer than deposits near the watershed outlet. Several trees in the channel show evidence of damage from the debris flow.

Postfire debris-flow deposit in the 2024 Elk Fire burn area near Dayton, Wyoming. A debris flow triggered by a July 2025 thunderstorm deposited sediment and woody debris within the channel. Downed trees, oriented perpendicular to the channel banks, form a wood dam.

Samples of Lava Creek Tuff, which erupted during the formation of Yellowstone Caldera about 631,000 years ago, with large quartz and sanidine crystals circled in red. Photos by Faith Nolander, July 22, 2025.

A close-up (microscope) image of a sanidine crystal from the Lava Creek Tuff, which erupted during the formation of Yellowstone Caldera about 631,000 years ago, marked with a point where electron microprobe analysis was performed. The chemistry of that point is given, where each major element has a corresponding weight percent.

Montana State University researchers recording data at an outcrop in Yellowstone National Park. M.S. student Liv Wheeler (right) overlays the GPS position of the outcrop over a geologic map produced by USGS geologist Robert Christianson, while undergraduate student Liam Arnold (left) notes other data related to the outcrop.

Example of a Yellowstone seismic waveform recorded at station YMC (at Maple Creek in the northeast part of Yellowstone National Park) with earthquakes for which a magnitude could not be determined. The magnitude was therefore set at -9.99 in the University of Utah Seismograph Stations catalog.

A map of the stations operating in the Yellowstone region between 2012 and 2024 shown as triangles with fill and edge colors indicating whether they are used to calculate magnitudes using traditional approaches, artificial intelligence methods, or both.

In a North American reference frame, where motion of the North American plate has been removed, you can easily see how the GPS stations around the region are moving in slightly different ways.

Geodatabase entry for a sample of the Lava Creek Tuff, which is a result of the eruption that formed Yellowstone Caldera about 631,000 years ago.  Top: A selected point in the ArcGIS geodatabase showing all the data recorded in the field as well as an image of the rock sample. Bottom: Topographic map showing the location of where the data were recorded.

Crystal springs watershed in the 2024 Elk fire burn area.  The USGS installed a monitoring station here to record postfire hydrologic responses during rainfall events.  This photo was taken before any flooding or debris flows occurred, but the station later recorded a debris flow during a July 2025 thunderstorm.  

USGS postfire monitoring station in the Elk Fire burn area near Dayton, Wyoming. Installed less than a year after the wildfire, the station records hydrologic responses during rainfall on the burned landscape. Located above a channel that was assessed to have a very high likelihood of debris flows, it collects data on soil properties and rainfall.

USGS scientists install a postfire monitoring station in the Elk Fire burn area near Dayton, Wyoming. Installed less than a year after the wildfire, the station records hydrologic responses during rainfall on the burned landscape.

A USGS hydrologist checks a newly installed rain gage in the Elk Fire burn area near Dayton, Wyoming to ensure that it is level. USGS scientists installed several rain gages throughout the Elk Fire burn area. Rain gage data is paired with observations of flooding and debris-flows to test how well the USGS hazard assessment models are working.