vendredi, sept. 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. ... [details]
Mount Rainier volcanMount 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.
Introduction: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.
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