Geologist says Yellowstone hydrothermal explosion is not an indicator of a larger eruption

A West Virginia University researcher says Tuesday’s (July 23) surprise hydrothermal explosion at Yellowstone National Park’s Biscuit Basin doesn’t mean a larger eruption of the Yellowstone volcano is imminent. The explosion, captured on video by park visitors, launched debris into the air and damaged the boardwalk, but no one was injured.

According to Jaime Toro, professor of geology at the WVU Eberly College of Arts and Sciences, some geothermal features, like geysers, are more regular than others. While the Biscuit Basin explosion was unexpected, such an event is a part of the geology of the region.

Quotes:

“Yellowstone is the largest active volcano in North America. The crater alone is so big that most tourists don’t realize they are in it when they visit the National Park. It is up to 40 miles wide. That crater is the hole left after the last set of major eruptions, which happened between 2.1 million and 600,000 years ago. The largest of these events erupted about 600 cubic miles of ash, which blanketed most of the western U.S. and left a layer up to 400 feet thick in some areas near Yellowstone. Another eruption of that size would be a civilization-ending sort of event.

“Fortunately, what happened Tuesday (July 23) is a spectacular, but very minor event. It is nothing to worry about, unless you happened to be on the Biscuit Basin boardwalk at the time. The power of Yellowstone comes from what geologists call a ‘hotspot.’ That is, the spot on the surface above a plume of hot material that rises from the core-mantle boundary of the Earth, 1,800 miles below. If you look at Google Earth, you will see a broad arc of low topography that cuts across southern Idaho and ends in Yellowstone. This is the track left by the hotspot as the North American plate moved over it during the last few million years.

“Most of the evidence of volcanic activity that tourists see at Yellowstone is due to the interaction of groundwater with the hot rock that covers the volcano’s magma chamber. Water seeps down through cracks and fractures and heats up. At the Old Faithful geyser, in the course of an hour, the water at depth begins to expand and rise. As it rises, it lowers the pressure of the water below, which flashes to steam causing the geyser to spew the water out. The plumbing of that geyser is such that the process repeats itself cyclically. Other geysers are much less regular. Some erupt at irregular intervals, while some may spend years or decades quietly stewing before they erupt.

“In the case of Biscuit Basin, it appears there was no easy path for the steam to escape, allowing internal pressure to rise to the point that it blew the top off of the geyser. In the videos, you can see a plume of black material thrown into the air. That is rock that was capping the steam reservoir before the eruption. There is no telling when this might happen again, but as long as the hotspot remains active, Yellowstone will continue to amaze us.” — Jaime Toro, professor of geology, Department of Geology and Geography, WVU Eberly College of Arts and Sciences