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Characterizing Pyroclastic-Flow Interactions with Snow and Water Using Environmental Magnetism at Augustine Volcano

Professional Paper 1769-11

Chapter 11 of Power, J.A., Coombs, M.L., and Freymueller, J.T., eds., The 2006 eruption of Augustine Volcano, Alaska
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Abstract

In-place measurements of environmental magnetic susceptibility of pyroclastic flows, surges and lahars emplaced during the 2006 eruption of Augustine Volcano show that primary volume magnetic susceptibilities of pyroclastic materials decreased where the flows encountered water and steam. The Rocky Point pyroclastic flow, the largest flow of the eruption sequence, encountered a small pond near the north coast of Augustine Island where local interactions with water and steam caused susceptibilities to decrease from 1,084+128x10-5 SI to 615+114x10-5 SI. Ash produced during phreatic explosions and pyroclastic surges that crossed snow also produced deposits with reduced susceptibilities, while lahar deposits derived from pyroclastic flows showed even greater reductions in susceptibility (430+129x10-5 SI). The susceptibility reductions are probably largely attributable to oxidation of iron in magnetite and other minerals within the pyroclastic flows, although other physiochemical processes may play a role. Measurements of the magnetic properties of pyroclastic flows, surges, and lahar deposits can be a useful tool in understanding the processes that occur when pyroclastic flows encounter ice, snow, and water and interact with water and steam on the slopes of active volcanoes.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Characterizing Pyroclastic-Flow Interactions with Snow and Water Using Environmental Magnetism at Augustine Volcano
Series title:
Professional Paper
Series number:
1769
Chapter:
11
Edition:
-
Year Published:
2010
Language:
ENGLISH
Publisher:
U.S. Geological Survey
Contributing office(s):
Alaska Volcano Observatory
Description:
15 p.; p. 269-283
Online Only (Y/N):
Y
Additional Online Files(Y/N):
N