Geothermal Activity Closes Portion of Yellowstone

July 24, 2003 

YELLOWSTONE NATIONAL PARK, Wyo. (AP) -- Unexpected geothermal activity in the Norris Geyser Basin on the park's westside has forced closure of about half the trails because of safety concerns, park officials said Thursday.

The National Park Service said new steam vents and mud pots are popping up, some geysers are draining themselves and the Porkchop geyser has erupted for the first time since 1989.

The ground temperature also has risen to 200 degrees Fahrenheit in places, hot enough to cook eggs on bare ground and boil water at Yellowstone's altitude.

Officials said there are 12,500 feet of trails in the basin and 5,800 of them are now closed until "conditions have returned to acceptable ground temperatures and stable surface conditions."

"It sounds like they're having some growing pains down there," said Tim McDermott, codirector of the Thermal Biology Institute at Montana State University.

Norris is the park's hottest and most seismically active of geyser basin, a place where change is constant.

McDermott's work calls on him to sample the heated waters of the geyser basin and derive useful products from the microbes living in them.

The increased activity was first noticed July 11 and Porkchop geyser erupted July 16, the first time it's blown in 14 years. Prior to 1989, that geyser was in continuous eruption for four years, a period that ended with an "explosion," the Park Service said.

Officials said there has been no evidence of unusual geothermal activity in other areas of Yellowstone.

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