Thermal activity halts vehicle traffic near Mammoth Hot Springs

Once the log bumbers are in place, Upper Terrace Drive near Mammoth Hot Springs will reopen. (YNP photo)

YNP new release

MAMMOTH HOT SPRINGS, YNP  — Rangers temporarily closed Upper Terrace Drive near Mammoth Hot Springs in Yellowstone National Park to vehicles due to new thermal features that is impacting the road.

The feature became visibly active this May near the Upper Terrace parking lot, creating new small terraces adjacent to the drive. Geologists and rangers monitored the thermal feature and found temperatures up to 152 degrees Fahrenheit. Rangers noticed additional thermal activity this week adjacent to and under the pavement, prompting the temporary closure. Thermal imaging shows heat under the pavement as well.

“We have known this area had heat near the surface on the fact that it does not hold snow in the winter,” said Dr. Hank Heasler, park geologist. “We drilled two 20-inch deep holes, both of which now have hot water bubbling at the surface or very near the surface.”

Park visitors are still able to walk the Upper Terrace Drive. Maintenance staff is preparing bumper logs to protect the thermal feature and keep outflow off the pavement. Once those are in place, the drive will reopen to vehicle traffic.

“As in all of the thermal areas, visitors need to stay on the boardwalk or paved areas and avoid touching thermal features,” Heasler said.