Scientists are responding to several volcanoes in the United States
that are erupting or showing signs of restless activity in order
to provide up-to-date hazard assessments and warnings of potential
eruptions to the public. See current updates
for the latest.
Mount St. Helens. Close view of the southern half of the
lava dome in the crater of Mount St. Helens. USGS photograph taken
on 11 October 2004 by Jon Major (click
here for very large image). Earthquakes and intermittent steam
and ash emissions continue at the volcano, and scientists observed
lava at the surface of the lava dome on October 11 with temperatures
as high as 600o C (center part of photo above).
Scientists of the USGS Cascades Volcano Observatory and University
of Washington Geophysics Program are monitoring the activity closely
and releasing regular updates
and photos
of the activty.
In
Alaska, a swarm of earthquakes 2 to 3 km beneath the summit cone
of Mount Spurr volcano, located 130 km west of Anchorage, was first
noticed in early July by scientists of the Alaska Volcano Observatory
(AVO). Aerial reconnaissance in mid-July and early August revealed
recent small flows of mud and rock and a new "ice cauldron"
in the summit ice cap. The ice cauldron is a collapse feature possibly
caused by an increase in heat coming from deep beneath the summit.
Scientists have also measured volcanic gases escaping from the summit
cone. See current
information about Spurr. The most recent eruption of Spurr occurred
in 1992 (see summary
of the 1992 eruption precursors and the eruption warnings and public
statements issued by AVO.
AVO scientists are also monitoring closely the continuing eruption
and restless activity at Veniaminoff
and Shishaldin
volcanoes.
The
ongoing eruption of Kilauea Volcano, Hawaii, continues to capture
the attention of scientists from the USGS Hawaiian Volcano Observatory
as lava flows spread from the active vent, Pu`u `O`o (see eruption
update). In late July, a swarm of deep (>40 km) earthquakes
beneath nearby Mauna Loa volcano was detected by HVO scientists.
Beginning in April or early May 2002, a GPS network on the volcano
showed definite lengthening of the lines across the summit caldera,
indicating the volcano was inflating after nearly 10 years of slight
deflation. Scientists infer that the volcano's magma reservoir is
swelling with new magma. This past summer, HVO scientists have worked
to install new GPS instruments and upgrade seismic stations on the
volcano. See Mauna
Loa current activity from HVO.
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