Active volcanoes dominate the skyline
in many parts of
the Pacific Northwest. These familiar snow-clad peaks are
part of a 1,000 mile-long chain of volcanoes, the
Cascade Range, which extends from northern California to
southern British Columbia. Many of these volcanoes have
erupted in the recent past and will erupt again in the
foreseeable future. The time between eruptions is
usually measured in decades or centuries, so eruptions
are not a part of our everyday experience. However, in
1980 Mount St. Helens vividly demonstrated the power
that Cascade volcanoes can unleash when they do erupt.
The U.S. Geological Survey (USGS) is responsible for
assessing volcano hazards, monitoring the activity of
U.S. volcanoes, and issuing warnings of impending
eruptions. To help prevent loss of life and property
from the next eruption in the Cascades, scientists at
the USGS Cascades Volcano Observatory (CVO) in
Vancouver, Washington, are working to determine the type
and extent of hazards posed by the Cascade volcanoes.
Cascade Volcanoes
Eruptions in the Cascades
have occurred at an average
rate of 1-2 per century during the last 4000 years, and
future eruptions are certain. Seven volcanoes in the
Cascades have erupted since the first U.S. Independence
Day a little more than 200 years ago. Four of those
eruptions would have caused considerable property damage
and loss of life if they had occurred today without
warning. As population increases in the Pacific
Northwest, areas near the volcanoes are being developed
and recreational usage is expanding. As a result, more
and more people and property are at risk from volcanic
activity. The next eruption in the Cascades could affect
hundreds of thousands of people.
VOLCANOES AND WATER: A Dangerous Combination
Large parts of most Cascade volcanoes are covered with
permanent snow and ice that pose a special hazard during
periods of volcanic unrest. Even small eruptions can
melt a large amount of snow and ice, triggering debris
flows that can travel tens of miles beyond the flanks of
the volcano into populated valleys. Years after volcanic
unrest has stopped, erosion of deposits can cause
increased sediment that clogs waterways, disrupts
aquatic ecosystems, and worsens flooding. Debris flows
are the most costly effects of eruptions at snow-clad
volcanoes.
USGS CASCADES VOLCANO OBSERVATORY
-- Preparing for the Next Eruption
EVALUATING Volcano Hazards:
To identify the areas that are likely to be affected by
future eruptions, rock deposits from pre-historic
eruptions are mapped, studied, and dated to learn about
the types and frequency of past eruptions at each
volcano. This information helps scientists to better
anticipate future activity at a volcano, and provides a
basis for mitigating the effects of future eruptions
through land-use and emergency planning.
MONITORING Restless Volcanoes:
Volcanoes often show signs that they are getting ready
to erupt days to months in advance. Seismic activity,
ground movements, and gas emissions at Cascade volcanoes
are monitored by CVO in order to detect subtle changes
that may herald the next eruption. Seismic activity is
continuously monitored under the auspices of the USGS
Volcano Hazards and Geothermal Studies Program through
CVO, the USGS in Menlo Park, California, and the
University of Washington Geophysics Program in Seattle,
Washington.
COMMUNICATING Hazards Information
CVO provides information about volcanoes and volcano
hazards to public officials, land-use planners,
emergency response organizations, the Federal Aviation
Administration and other federal agencies, the news
media, schools, and the general public. When volcanic
activity increases, CVO issues advisories, warnings, and
whenever possible, specific predictions concerning
eruptions and their potential impacts.
DEVELOPING New Tools, Testing New Ideas:
USGS scientists study Mount St. Helens and other
volcanoes around the world to develop new ideas about
how volcanoes work and to improve eruption-prediction
methods. Related research topics include dynamics of
debris flows, effects of volcanic gases on weather and
climate, and effects of increased sediment transport on
streams. New instrumentation, software, and hardware
developed by the USGS enable scientists to acquire,
process, and interpret data more quickly and effectively
than ever before.
READY to Respond:
At CVO, a multi-disciplinary team of scientists and a
cache of portable volcano-monitoring equipment function
as a mobile volcano observatory ready to respond to
volcanic unrest anywhere in the U. S. and, in cooperation
with the U. S. Agency for International Development's
Office of Foreign Disaster Assistance, anywhere in the
world. Since 1980 this team has responded to volcanic
unrest in Alaska, California, Washington, Colombia,
Ecuador, Guatemala, Indonesia, Mexico, Papua New Guinea,
and the Philippines.
The USGS Cascades Volcano Observatory strives to serve
the national interest by helping people to live
knowledgeably and safely with volcanoes and related
natural hazards including earthquakes, landslides, and
debris flows in the western United States and elsewhere
in the world. CVO assesses hazards before they occur by
identifying and studying past hazardous events. We
provide warnings during volcanic crises by intensively
monitoring restless volcanoes and interpreting results
in the context of current hazards assessments. We
investigate and report on hazardous events after they
occur to improve our assessment and prediction skills,
and to help develop new concepts of how volcanoes work.
Our goal is to keep natural processes from becoming
natural disasters.
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