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To study active volcanism,
the Volcano Hazards Program depends principally on the
research and monitoring conducted at three
permanent installations: the Hawaiian, Cascades,
and Alaska Volcano Observatories*.
Each
observatory provides continuous and periodic
monitoring of the seismicity, other geophysical
changes, ground movements, gas chemistry,
and hydrologic conditions and activity between
and during eruptions. They also provide
a detailed record of eruptions in progress.
These observations serve to characterize eruptive
behavior, identify the nature of precursory
activity leading to eruption, define the processes
by which different types of deposits are emplaced,
and specify the hazards that could be
unleashed by each kind of eruption. From direct
observation of precursory signs, it is possible
to anticipate eruptions. Underlying all observatory
operations is an ongoing program of
fundamental research in volcanic processes,
supplemented by collaborative studies conducted
at other USGS centers. Such research typically
includes direct interpretation
of the monitoring and eruption data, and it
leads to formulation of conceptual models that
can be tested by theoretical or laboratory simulations
of volcanic systems.
The Hawaiian Volcano Observatory (HVO)
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HVO is the U. S. Geological Survey's oldest such
facility, founded in 1912 by Thomas A. Jaggar and
run continuously by the USGS since 1948
(Heliker and others, 1986). It is located on the
summit of Kilauea, one of the most active volcanoes
in the world, on the Island of Hawaii. With the
frequent eruptions at Kilauea and nearby Mauna
Loa, HVO is a training ground for most of
the volcanologists at the USGS. Many volcano-monitoring
techniques used worldwide were
originally developed at HVO, which is a testing
ground for new techniques and instruments.
The existence of HVO gave the USGS the
unique capability of responding to activity at
other U.S. volcanoes. When Mount St. Helens
reawakened in March 1980, the USGS was well
prepared to respond to the crisis. Scientists who
had previously deciphered the volcanic history
of Mount St. Helens, together with HVO alumni,
quickly assembled to monitor the seismic activity
and steam explosions. All worked together
with the many agencies and public officials
who were anxious to know when and if a large
eruption was going to occur and what hazards
it might create. Guided by USGS information,
public officials designated zones of restricted
access, and the loss of life from the May 18th
eruption was thereby minimized, even though
the timing of this event could not be precisely
predicted.
Cascades Volcano Observatory (CVO)
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After the devastating explosive eruption in
1980, the Cascades Volcano Observatory (CVO),
in Vancouver, Washington, was founded and
staffed with hydrologists, geologists, geochemists,
and geophysicists (Brantley and Topinka,
1984). The observatory quickly broke new
ground in its study of the ongoing eruption
cycle at Mount St. Helens. In mapping and
interpreting the origin of the deposits of the May
18 eruption, scientists had the unique advantage
of direct observation of the landslides,
eruption, and volcanic debris flows. Monitoring
the growth of the lava dome in the crater of
Mount St. Helens resulted in accurate predictions,
1 to 3 days in advance, of 16 out of 17
dome-building eruptions-an unprecedented
feat in the young science of volcanology.
Alaska Volcano Observatory (AVO)
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In 1988, the USGS added a third volcano
observatory, the Alaska Volcano Observatory
(AVO), in Anchorage and Fairbanks, Alaska, to
expand and coordinate existing monitoring of
the many active volcanoes along the Alaska
Peninsula and in the Aleutian Islands. Many
international flightpaths lie directly over Alaska,
and the frequent eruptions of these volcanoes
pose a serious hazard to aircraft far
downwind. Study of Alaskan eruptions also
provides more frequent opportunities to study
volcanic activity similar to that of the less
frequently active Cascade Range volcanoes.
Long Valley Observatory (LVO)*
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In May 1980, just 1 week after the eruption
at Mount St. Helens, a strong earthquake swarm
occurred at Long Valley, California, site of a
huge eruption of silicic magma about 700,000
years ago. The most recent volcanic activity in
the area resulted in the formation of lava domes
550 years ago, accompanied by phreatic explosions
that blanketed much of eastern California
and western Nevada with volcanic ash (Bailey
and others, 1976; Miller, 1985). Following the
1980 earthquakes, the USGS began monitoring
Long Valley by setting up an observatory-like
project operated from the USGS center in Menlo
Park, California. Studies conducted since 1980
have documented almost 2 feet of uplift of the
ground within the Long Valley Caldera and
have accurately located earthquakes occurring
as swarms in and around the caldera, the most
recent of which took place in 1990 and 1991.
The work at Long Valley is designed to monitor
and interpret the current unrest and to make
forecasts of any activity that might occur. Thus,
the Long Valley project effectively constitutes a
fourth volcano observatory in function and
responsibilities, if not in name. The largest
possible volcanic event at Long Valley, a catastrophic
explosive eruption associated with renewed
caldera collapse, is also the most difficult to
forecast because of the long time interval between
such eruptions and the absence of historically
documented large caldera-forming eruptions
anywhere in the world.
Yellowstone Volcano Observatory (YVO)*
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The Yellowstone Volcano Observatory is the most
recent U.S. volcano observatory.
To strengthen the long-term monitoring of volcanic
and earthquake unrest in the Yellowstone National
Park region, on 14 May 2001 the U.S. Geological Survey (USGS),
Yellowstone National Park, and
University of Utah entered into an agreement
to establish the Yellowstone Volcano Observatory
(YVO).
The goal of the
observatory is to improve the existing collaborative
study and monitoring of active geologic processes
and hazards of the Yellowstone Plateau volcanic
field and its caldera. The Observatory is supported
by the U.S. Geological Survey, University of Utah,
and the Yellowstone National Park. The park was the
world's first National Park. It contains the
largest and most diverse collection of natural
thermal features in the world.
*
Long Valley Observatory established as permanent observatory
since this report was written. The Yellowstone Volcano Observatory was
established in 2001.
Information about the Yellowstone Volcano Observatory courtesy
Volcano Hazards Program Website, 2002, and
Yellowstone Volcano Observatory Website, 2002
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