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Volcanic mixed avalanches: a distinct eruption-triggered mass-flow process at snow-clad volcanoes

Geological Society of America Bulletin

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Abstract

A generally unrecognized type of pyroclastic deposit was produced by rapid avalanches of intimately mixed snow and hot pyroclastic debris during eruptions at Mount St. Helens, Nevado del Ruiz, and Redoubt Volcano between 1982 and 1989. These "mixed avalanches' traveled as far as 14 km at velocities up to ~27 m/s, involved as much as 107 m3 of rock and ice, and left unmelted deposits of single flow units as thick as 5 m. During flow downslope, heat transfer from hot rocks to snow produced meltwater that partially saturated the mixtures, apparently giving these mixed avalanches mobilities equal to or greater than those of "dry' debris avalanches of similar volume. After melting and desiccation, the deposits are highly susceptible to erosion and unlikely to be well preserved in the stratigraphic record. -Authors

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Volcanic mixed avalanches: a distinct eruption-triggered mass-flow process at snow-clad volcanoes
Series title:
Geological Society of America Bulletin
Volume
106
Issue:
10
Year Published:
1994
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geological Society of America Bulletin
First page:
1351
Last page:
1358
Number of Pages:
8