Biscuit Basin closes for season following hydrothermal blast

Yellowstone National Park has closed the Biscuit Basin area for the season after a hydrothermal explosion strewed boiling water and rocks skyward Tuesday morning, destroying a section of boardwalk and spurring frightened tourists to flee.
No one was injured in the blast at Black Diamond Pool, which was caused by hydrothermal conditions and not volcanic activity, the park said Wednesday. Geologists are monitoring conditions, mapping the debris field and sampling water to assess any changes in the hydrothermal system, according to the park.
Small explosions of boiling water from the area continue to be possible over the coming days to months, and it will be off-limits to visitors for the duration of the season.
A preliminary report, meanwhile, sheds light on what scientists understand so far about the explosion.
Grapefruit-sized rocks