A churning body of water has formed in Yellowstone National Park just two days after researchers walked across that same ground. The location became a silt-gray depression the size of a small pool, releasing steam and thumping sounds from boiling liquid. No one witnessed the change occur. The feature emerged in Biscuit Basin between June 14 and 16, following a minor hydrothermal blast on June 13. It marks the second such occurrence in the basin within two years. Officials from the US Geological Survey noted that the event highlights the active and dangerous character of geothermal processes in the area. A prior blast in July 2024 propelled rocks and hot water outward, damaging walkways and visitor facilities. The recent episode proved smaller in scale, with no injuries reported in either case. Researchers recorded the June 13 eruption using monitoring equipment that detected seismic signals and low-frequency sound from the direction of Black Diamond Pool. After sunrise, the Firehole River downstream showed a milky gray plume. Sensors indicated only minor temperature change at the pool itself, pointing to activity elsewhere. Camera footage later confirmed steam rising north of Black Diamond Pool at the exact time of the signals. Site inspection the following day found three new vents releasing near-boiling water into the river. The water had cooled to about 85 degrees Celsius upon arrival. A fissure 18.5 meters long and 1.5 meters wide continued to discharge hot liquid, surrounded by ejected rocks that traveled short distances. No pool existed at that stage. Upon return on June 16, staff discovered an active boiling gray pool measuring 6.5 by 5.3 meters that produced thumping noises from collapsing steam bubbles. The feature likely formed through ground collapse rather than explosion, based on absent debris. Later recordings showed intermittent water jets reaching 6 to 9 meters high, indicating ongoing activity. Similar new features have appeared in Yellowstone before, including another pool last summer in Porcelain Basin. This incident stands out as the closest hydrothermal explosion to monitoring instruments, providing extensive recorded data.
