Friday, Sep 14, 2012
An M 2.4 earthquake occurred beneath the summit of Mount Rainier at 08:45 PDT, September 13, and was followed by a dozen or so aftershocks over the next ~20 minutes. ... [more]
Mount Rainier volcanoMount Rainier, the highest peak in the Cascade Range, is located 87 km SE of Seattle and forms a majestic backdrop to the landscape of the region. The volcano is covered by 26 main glaciers, and melting of glacial ice by a future eruption causing lahars are a significant hazard for the region.
Reported 19th-century eruptions can not be verified by any deposits, but it is likely that some phreatic activity took place in 1894.
Previous eruptions have produced large debris avalanches and lahars, some of which have traveled all the way to the Pacific Ocean and reached Puget Sound.
Background:Mount Rainier is a typical andesitic stratovolcano. It has produced large lahars and debris avalanches. Its present summit was built within a large crater breached to the northeast formed by collapse of the volcano during a major explosive eruption about 5600 years ago, that produced the widespread Osceola Mudflow.
Mt Rainier's eruptive history has been studied in detail. It includes about a dozen major eruptions during the past 2600 years, the largest of which occurred about 2200 years ago.
The present-day summit cone is cut by two overlapping craters. Extensive hydrothermal activity is present in the summit craters. It has produced melting of glacial ice created a complex system of steam caves found in the summit icecap.
Prominent features on and around Mt. RainierSummit of Mt Rainier:
There are 3 peaks: Columbia Crest at 14,158 feet (4315 m), Point Success at 14,158 feet (4315 m), and Liberty Cap at 14,112 feet (4301 m). Little Tahoma (11,138 ft / 3395 m) is a small peak located on the eastern flank of the volcano.
Camp Muir: A stone shelter cabin located at ca. 10,000 ft.
Camp Hazard: A campsite is located at 11,600 ft below Ice Cliff.
Carbon Glacier: The thickest and 3rd largest of Mt Rainier. Its terminus is at 3,500 ft. It is 5.7 miles long and 700 ft thick.
Russell Glacier: a tributary to the Carbon Glacier on the north side.
Cowlitz Glacier: The Cowlitz-lngraham Glacier advanced from the mid-1970's until the mid-1980's, but is currently thinning and retreating.
Echo Rock: an old volcanic vent on the NW flank.
Emmons Glacier: a large glacier on the eastern slope of the mountian. In 1963, a rockfall from Little Tahoma Peak covered the lower glacier with rock debris. The debris cover insulates the ice from melting. As a result of decreased melting, the glacier advanced rapidly in the early 1980's. That advance is still continuing today, but at a slower rate.
Nisqually Glacier: The glacier can be viewed from Nisqually and Glacier Vistas located less than 1 mile from the Paradise visitor facilities.
Winthrop Glacier: the second largest glacier on Mount Rainier, with an area of 3.5 square miles.