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Mid-holocene sector collapse at Mount Spurr Volcano, South-Central Alaska

December 12, 2007

Radiocarbon-dated volcanic mass-flow deposits on the southeast flank of Mount Spurr in south-central Alaska provide strong evidence for the timing of large-scale destruction of the south flank of the volcano by sector collapse at 4,769^ndash;4,610 yr B.P. The sector collapse created an avalanche caldera and produced an ~1-km3-volume clay-rich debris avalanche that flowed into the glacially scoured Chakachatna River valley, where it transformed into a lahar that extended an unknown distance beyond the debris avalanche. Hydrothermal alteration, an unbuttressed south flank of the volcano, and local structure have been identified as plausible factors contributing to the instability of the edifice. The sector collapse at Mount Spurr is one of the later known large-volume (>1 km,sup>3) flank failures recognized in the Aleutian Arc and one of the few known Alaskan examples of transformation of a debris avalanche into a lahar.

Citation Information

Publication Year 2007
Title Mid-holocene sector collapse at Mount Spurr Volcano, South-Central Alaska
DOI 10.3133/pp1739C
Authors Christopher F. Waythomas
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Professional Paper
Series Number 1739
Index ID pp1739C
Record Source USGS Publications Warehouse
USGS Organization Volcano Hazards Program

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