By Merve Berker
ANKARA (AA) – A new hydrothermal pool has formed at Yellowstone National Park’s Norris Geyser Basin, geologists from the US Geological Survey announced, marking another sign of ongoing geological activity beneath the park’s surface.
The pool, discovered in April 2025 during routine temperature monitoring, is located in the Porcelain Basin near a vegetated area known as Tree Island.
According to the US Geological Survey, the light blue spring is approximately 13 feet in diameter and one foot deep.
It is surrounded by rocks measuring approximately one foot across and covered in light gray, sandy mud.
Geologists believe the pool resulted from a hydrothermal explosion, a common occurrence in the area caused by rapid steam generation due to subsurface pressure changes.
“It is not surprising that a hydrothermal explosion occurred at this site,” the agency said, citing the North Geyser Basin as “the most dynamic” part of Yellowstone.
High-resolution satellite images show the pool was not present on Dec. 19 but had begun forming by Jan. 6 and was filled with water by Feb. 13.
Unlike the July 2024 explosion in Biscuit Basin, which formed a large crater in a single event, the new pool likely developed from a series of small explosions that gradually created a silica-rich water pit, the US Geological Survey added.