USGS/Cascades Volcano Observatory, Vancouver, Washington
REPORT:
Potential Hazards from Future Eruptions in the Vicinity of Mount Shasta Volcano,
Northern California
--
C. Dan Miller, 1980,
Potential Hazards from Future Eruptions in the Vicinity of Mount Shasta Volcano,
Northern California:
U.S. Geological Survey Bulletin 1503, 43p.
Abstract
Mount Shasta has erupted, on the average, at least once per 800 years during
the last 10,000 years, and about once per 600 years during the last 4,500 years.
The last known eruption occurred about 200 radiocarbon years ago. Eruptions
during the last 10,000 years produced lava flows and domes on and around the
flanks of Mount Shasta, and pyroclastic flows from summit and flank vents
extended as far as 20 kilometers from the summit. Most of these eruptions also
produced large mudflows, many of which reached more than several tens of
kilometers from Mount Shasta. Future eruptions like those of the past could
endanger the communities of Weed, Mount Shasta, McCloud, and Dunsmuir, located
at or near the base of Mount Shasta. Such eruptions will most likely produce
deposits of lithic ash, lava flows, domes, and pyroclastic flows. Lava flows
and pyroclastic flows may affect low-and flat-lying ground almost anywhere
within about 20 kilometers of the summit of Mount Shasta, and mudflows may cover
valley floors and other low areas as much as several tens of kilometers from the
volcano. On the basis of its past behavior, Mount Shasta is not likely to erupt
large volumes of pumiceous ash in the future; areas subject to the greatest risk
from air-fall tephra are located mainly east and within about 50 kilometers of
the summit of the volcano. The degree of risk from air-fall tephra decreases
progressively as the distance from the volcano increases.
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07/01/97, Lyn Topinka