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Detailed map of Mount Rainier's summit and northeast slope showing upper perimeter of Osceola collapse amphitheater (hachured line) The Osceola Mudflow, also known as the Osceola Lahar, was a debris flow and lahar in the U.S. state of Washington that descended from the summit and northeast slope of Mount Rainier, a volcano in the Cascade Range during a period of eruptions about 5,600 years ago.
Debris flows with volumes ranging up to about 100,000 cubic meters occur frequently in mountainous regions worldwide. The largest prehistoric flows have had volumes exceeding 1 billion cubic meters (i.e., 1 cubic kilometer). As a result of their high sediment concentrations and mobility, debris flows can be very destructive.
Today the bottom of Spirit Lake is 100 ft (30 m) above the original surface, and it has two and a half times more surface area than it did before the eruption. The largest known of all prehistoric landslides was an enormous submarine landslide that disintegrated 60,000 years ago and produced the longest flow of sand and mud yet documented on ...
The third event followed about 500 years ago with the deposition of two diamicton units along Turbid Creek and was the smallest of the three major prehistoric debris avalanches. A lack of organic and paleosol horizons between the two units implies that they most likely represent separate surges within the same debris avalanche event. [13]
One of the possible issues with this timing was the continental debris cluttering up the seaway between the two plates in question. This debris, along with what is known as the Shackleton fracture zone , has been shown in a recent study to be fairly young, only about 8 million years old. [ 102 ]
However, also dry debris can exhibit flow-like movement. [30] Flowing debris or mud may pick up trees, houses and cars, and block bridges and rivers causing flooding along its path. This phenomenon is particularly hazardous in alpine areas, where narrow gorges and steep valleys are conducive of faster flows. Debris and mud flows may initiate on ...
An archaeologist works on the recently discovered remains of a victim in the archaeological site of the ancient city of Pompeii, which was destroyed in AD 79 by the eruption of Mount Vesuvius, in ...
Most of the lava continued to flow westward through Klastline Valley and reached the Stikine River. [121] [131] Lava flows overlying sediment at the mouth of the Tahltan River. Lava of the Klastline eruptive period continued to flow 55 kilometres (34 miles) downstream along the Stikine River from its confluence with the Klastline River. [142]