January 15, 2008

Yellowstone Craters Linked to Massive Waves

The world's largest known hydrothermal explosion 13,000 years ago may have been created by tsunami-sized waves. That particular explosion created the Mary Bay crater which lies along the north edge of Yellowstone Lake and is over one mile across.

Lisa Morgan of the U.S. Geological Survey said that there have been 20 hydrothermal explosions in Yellowstone over the past 14,000 years, most of them leaving craters more than 100 yards across. These explosions are much larger than the similar explosions in Yellowstone that happen almost every two years. The hydrothermal explosions occur when hot water just below the earth's surface flashes into steam and breaks through the surface.

Geologists are still trying to understand these larger explosions that happen approximately once every 700 years in Yellowstone. Morgan thinks that there were at least two big waves before the Mary Bay explosion. Evidence of these has been found more than 3 miles north of the lake. The column from the explosion may have been more than a mile high, and debris was spread across 18 square miles.

At some point, Morgan thinks, an earthquake may have created huge waves and displaced over 77 million cubic feet of water in Yellowstone Lake, resulting in the unsealing of a capped geothermal system.

For geologists, predicting when one of these larger explosions might happen again is difficult; however it is a topic worth studying.


On the Net:

U.S. Geological Survey