USGS/Cascades Volcano Observatory, Vancouver, Washington
REPORT:
Volcano Hazards in the Mount Hood Region, Oregon
--
W.E. Scott,
T.C. Pierson,
S.P. Schilling,
J.E. Costa,
C.A. Gardner,
J.W. Vallance, and
J.J. Major, 1997,
Volcano Hazards in the Mount Hood Region, Oregon:
U.S. Geological Survey Open-File Report 97-89, 14p.
Summary
Mount Hood is a potentially active volcano
close to rapidly growing communities and recreation
areas. The most likely widespread and hazardous
consequence of a future eruption will be for lahars
(rapidly moving mudflows) to sweep down the entire
length of the Sandy (including the Zigzag) and White
River valleys. Lahars can be generated by hot volcanic
flows that melt snow and ice or by landslides from the
steep upper flanks of the volcano. Structures close to
river channels are at greatest risk of being
destroyed. The degree of hazard decreases as height
above a channel increases, but large lahars can affect
areas more than 30 vertical meters (100 vertical feet)
above river beds. The probability of eruption-
generated lahars affecting the Sandy and White River
valleys is 1-in-15 to 1-in-30 during the next 30
years, whereas the probability of extensive areas in
the Hood River Valley being affected by lahars is
about ten times less. The accompanying volcano-hazard-
zonation map outlines areas potentially at risk and
shows that some areas may be too close for a
reasonable chance of escape or survival during an
eruption. Future eruptions of Mount Hood could
seriously disrupt transportation (air, river, and
highway), some municipal water supplies, and
hydroelectric power generation and transmission in
northwest Oregon and southwest Washington.
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05/22/00, Lyn Topinka