Visitors ran for safety at Yellowstone National Park after a hydrothermal explosion sent rock and steam spewing into the air north of the Old Faithful geyser Tuesday, park officials said.<\/p>\n\n\n\n
There were no injuries, and the extent of the damage from the blast, which occurred in Biscuit Basin, about 2 miles northwest of Old Faithful, at around 10:19 a.m., was unknown, the National Park Service said in a statement<\/a>.<\/p>\n\n\n\n The type of explosion that happened Tuesday involves hot water and results in \u201cthe rapid ejection of boiling water, steam, mud, and rock fragments,\u201d according to the U.S. Geological Survey<\/a>.<\/p>\n\n\n\n Video of the eruption<\/a> showed people, including children, running as a column of black and gray material and vapor launched into the air.<\/p>\n\n\n\n Yellowstone is famed for its thermal features and hot pools.<\/p>\n\n\n\n Hydrothermal explosions happen when water at or near boiling point beneath the ground rapidly turns into stream because of a drop in pressure, the USGS says.<\/p>\n\n\n\n Explosions like Tuesday\u2019s \u201care relatively common in Yellowstone,\u201d the USGS said in a statement<\/a>. A small one happened in Norris Geyser Basin in April, and there was an explosion in Biscuit Basin in 2009, it said.<\/p>\n\n\n\n Photos posted by Yellowstone National Park show the nearby boardwalk covered in dirt, rocks and debris.<\/p>\n\n\n\n The boardwalk and a parking lot were closed for the time being because of safety concerns, the park service said. The explosion has nothing to do with volcanic activity, it noted.<\/p>\n\n\n\n Park and USGS staff members are monitoring the situation and will decide when the area can be reopened, officials said.<\/p>\n\n\n\n