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Rockfalls and Avalanches from Little Tahoma Peak on Mount Rainier, Washington

Bulletin 1221-A

By:
and

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Abstract

In December 1963 rockfalls from Little Tahoma Peak on the east side of Mount Rainier volcano fell onto Emmons Glacier and formed avalanches of rock debris that traveled about 4 miles down the glacier and the White River valley. In this distance, the rock debris descended as much as 6,200 feet in altitude. Minor lithologic differences and crosscutting relations indicate that the rockfalls caused at least seven separate avalanches, having an estimated total volume of 14 million cubic yards. The initial rockfall may have been caused by a small steam explosion near the base of Little Tahoma Peak. During movement, some of the avalanches were deflected from one side of the valley to the other. Calculations based on the height to which the avalanches rose on the valley walls suggest that their velocity reached at least 80 or 90 miles per hour. The unusually long distance some of the avalanches were transported is attributed to a cushion of trapped and compressed air at their base, which buoyed them up amid reduced friction.

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Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Rockfalls and Avalanches from Little Tahoma Peak on Mount Rainier, Washington
Series title:
Bulletin
Series number:
1221
Chapter:
A
Edition:
-
Year Published:
1965
Language:
ENGLISH
Publisher:
U.S. Geological Survey
Contributing office(s):
U.S. Geological Survey
Description:
p. A1-A30