More on Mt. Rainier

Since it's in my neighborhood I'll do a follow up on Jazz's post this morning on Mt Rainier.

Mt. Rainier is the largest of the Cascade volcanic peaks and is over 14,000 feet tall. It is covered with large ice fields and glaciers. It is also very close to the largest population center in the Pacific Northwest, the Seattle and Tacoma area. Although it is an active volcano fire is not the threat, it's the ice.

Mudflows are the most constant source of danger to the river valleys and lowlands around Mount Rainier. The largest recorded mudflow from Mount Rainier, the Osceola mudflow, occurred about 5700 years ago when the northeastern section of Mount Rainier's summit broke free and began to slide down the mountainside. The resulting avalanche of rock and ice was quickly converted by frictional heat into a mass of mud with a volume of about 4 cubic kilometers. The mud traveled over 100 kilometers down the the White River valley to the shore of Puget Sound, into what is now the middle of the cities of Seattle and Tacoma. The Osceola mudflow covered about 500 square kilometers of land with a layer of mud ranging in thickness from a few meters on the coastal plains to as much as 100 meters along old river beds. While this particular event seems safely remote in time, Mount Rainier is known to have produced more than fifty major mudflows in the past 10,000 years. On average, a major mudflow travels down the White River valley every 600 years. The next major mudflow could occur without warning at any time.

More information on all of the Cascade volcanoes can be found at the Cascades Volcano Observatory