World's largest geyser puts on rare show at Yellowstone

The world's largest geyser has exploded to life at Yellowstone National Park for the first time in eight years, sending a high pressure burst of steamy water 300 feet into the air, a park official said on Thursday.

The stream of 160 degree water released on Wednesday night by the so called Steamboat Geyser lasted for roughly 10 minutes, delighting a small number of "geyser gazers" who have waited years for such a show, Yellowstone spokesman Dan Hottle said.

"There are a lot of people who wait hour after hour, day after day, for things to erupt," he said.

Yellowstone visitors could potentially wait a lifetime for Steamboat Geyser, which has gone as long as 50 years between major eruptions. Steamboat Geyser last sent a superheated torrent of water hundreds of feet into the air in May 2005.

Yellowstone, which stretches across the states of Idaho, Montana and Wyoming, is the oldest and arguably best known US national park, attracting more than 3 million visitors a year.

The park contains half the world's geothermal features in the form of more than 300 geysers and countless hot springs, boiling mud pots and steam emitting fumaroles.

Old Faithful, the park's most famous geyser, gained its name by reliably spewing hot water and steam every 90 minutes.

Major eruptions of Yellowstone geysers can be likened to pressure cookers. They are caused when cold water from snowmelt and rain meets underlying rock liquefied by heat.

The mix creates steam that rises in temperature and pressure until it shoots through surface vents, carrying overlying water with it.

Geyser eruptions can trigger seismic tremors and have sometimes been mistaken for earthquakes by Yellowstone visitors.

"The ground shakes and you can hear it from several miles away. It sounds like a jet taking off," Hottle said.