In northwestern Wyoming, a giant has laid sleeping for nearly 70,000 years. The Yellowstone caldera, also referred to as the Yellowstone supervolcano, in Yellowstone National Park, is simultaneously an American icon of tourism and a looming beast capable of massive destruction. A source of both awe and fear, the supervolcano was a hot topic recently when the park saw an unexpected hydrothermal explosion that damaged a boardwalk and threatened nearby tourists.
In light of public concern, WVU Eberly College of Arts and Sciences professor of geology, Jaime Toro, explained that the event is merely a reflection of the region’s geological composition and does not indicate a greater eruption in the making.
The Yellowstone supervolcano rests in a hotspot of molten Earth pooling into a magma chamber, the land above rising as the chamber fills and falling as the magma solidifies. Volcano scientists have measured the land’s movement for approximately 100 years, and, within the past decade, the volcano has risen at above average rates.
Historically, the volcano’s eruptions have expelled lethal gasses, volcanic ash and debris and magma that blanketed a majority of the continental United States — evidence of a previous eruption was found as far as Louisiana. Discussions of the supervolcano often theorize on when Yellowstone will next erupt, an event typically nicknamed “The Big One.”
Although the prospect of a supervolcanic eruption is enough to cause concern, experts don’t find it likely anytime soon, and last week’s eruption is not a sign of impending disaster.
Hydrothermal explosions are a flashy result of steam in a confined area within a volcano system, leading to rising pressure that creates an eruption of the geyser. These events are largely unpredictable, and can be dangerous, with boiling water, steam, mud and rock potentially reaching heights of over 1 mile and up to 2.5 miles in radius, according to the Yellowstone Volcano Observatory.
The recent hydrothermal eruption arose from the park’s Biscuit Basin and launched debris spanning up to hundreds of feet into the air, damaging the area’s boardwalk and affecting nearby thermal pools. Despite park visitors being on the boardwalk at the time of the eruption, no injuries were reported.
Aside from a season closure of Biscuit Basin, the eruption is not expected to lead to any long-term concerns for the park.
“Fortunately, what happened [July 30] 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,” said Toro.
Hydrothermal eruptions occur at Yellowstone every year but are often small and located in the park’s non-recreational areas, and thus don’t receive the same level of attention from the public.
“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. … As it rises, it lowers the pressure of the water below, which flashes to steam causing the geyser to spew the water out,” said Toro. “Some [geysers] erupt at irregular intervals, while some may spend years or decades quietly stewing before they erupt.”
In comparison, the Yellowstone supervolcano has been dormant and stable for thousands of years, and even today’s level of activity does not indicate any potential for an eruption. For now, the Yellowstone Volcano Observatory expects the park’s only future volcanic events will be hydrothermal eruptions like last week’s and rare lava flows.
“There is no telling when this might happen again, but as long as the hotspot remains active, Yellowstone will continue to amaze us,” said Toro.
For more information, visit NPS.gov/yell.
