Last week, a major tourist thruway in Yellowstone National Park had to be shut down because the road melted. The road’s Wicked Witch of the West impression was caused by high temperatures in both the air and under the ground. Yellowstone sits atop a volcanic hotspot, and that heat helped cause the asphalt to soften and oil to well up onto the surface.
For some people, melting roads would seem to herald some kind of volcanic doom. But for Yellowstone, it’s all in a day’s work. Yellowstone spokesman Dan Hottle told USA Today, "We see this kind of thing quite a bit.” The hotspot is continually monitored by the scientists at the Yellowstone Volcano Observatory, and even though there has been increased earthquake activity and ground deformation in the past few months, researchers say there is no evidence of an imminent catastrophic eruption.
It’s not like melting asphalt in summer is unprecedented. In 2012, a plane at Reagan National Airport in DC got stuck on the tarmac after the asphalt under its wheels melted. And last year, during Europe’s heat wave, parts of the UK’s busiest road, the M25, shut down when parts of it melted. These incidents didn’t happen at volcanic hotspots, just in places where the temperatures got hot enough for the road to buckle.
Of course, a volcanic hotspot can definitely raise ground temperatures in the area, even beyond the summertime heat waves. But these kinds of ground temperatures aren’t unusual for Yellowstone—in fact, they help power some of the park’s most iconic attractions. Yellowstone’s famous geysers and hot springs are powered by the same heat from the shallow chamber of partially-molten rock that helped melt the roadway.
The road reopened on Monday, with park workers using sand and lime to repair the damaged section.