YELLOWSTONE NATIONAL PARK – A newly formed thermal pool has been discovered in the Porcelain Basin area of Norris Geyser Basin, according to a recent update from the Yellowstone Volcano Observatory (YVO) and Yellowstone National Park geologists.
The feature was first observed during routine temperature station maintenance on April 10, 2025. Geologists encountered a blue, warm spring—approximately 4 meters (13 feet) across and 30 centimeters (1 foot) deep—situated just west of a vegetated area known as “Tree Island.”
The new pool is surrounded by small rocks coated in fine gray mud, likely ejected during its formation. Analysis suggests the feature developed gradually between late December 2024 and early February 2025, likely through a series of minor hydrothermal events rather than a single major explosion.
High-resolution satellite images confirmed the pool was absent as of December 19, 2024. A depression appeared by January 6, and the pool was clearly visible by February 13. Acoustic monitoring installed in September 2023 picked up low-level infrasound signals—without corresponding seismic activity—on December 25, January 15, and February 11, further supporting the theory of multiple small explosive events.
Although Norris Geyser Basin is known for its dynamic and volatile thermal activity, the discovery adds another example of how hydrothermal features can evolve both violently and subtly. Recent history includes a larger explosion in the Porcelain Terrace area in April 2024 and the 1989 event at Porkchop Geyser.
Geologists say the new formation highlights the value of combined remote sensing, geophysical monitoring, and field observation in tracking Yellowstone’s ever-changing geothermal landscape.