Survey of Volcanoes
Volcanoes important in climate change
1991 Before the Eruption
This one-meter resolution image of Mount
Pinatubo, Philippines was collected March
6, 2001 by Space Imaging's IKONOS
satellite. The image features the volcano
located 90 kilometers north of Manila.
Once standing 1,780 meters (5,840 feet),
Mount Pinatubo was dormant for 600
years
until
1991
when
the
volcano
erupted twice in June of that year. The
volcano spewed millions of tons of ash
high into the atmosphere and covered
nearby Clark Air Base. The result was the
destruction
of
the
volcano's
summit,
reducing the elevation to 1,485 meters
and
leaving
behind
a
caldera
(huge
depression). Following the eruption there
were massive mudslides triggered by
heavy tropical rains that mixed with
volcanic ash. The homes for more than
100,000
people
were
destroyed.
The
image could be used for future mitigation
efforts, disaster response and recovery
operations
and
risk
management
assessment.
Credit: " spaceimaging.com"
Pinatubo91_ash_deposits_06-26-91.jpg
Tephra (ash) fall deposits of mid-June in schoolyard in Linasin (San Marcelino), Zambales, about 30
kilometers southwest of Pinatubo. The base l2 centimeters of brownish-gray ash fell between June
12th and early June 15th, 1991. It is overlain by 14 centimeters of thick pumice-fall deposit on the
afternoon of June 15th. Such tephra loads, along with typhoon rain and wind and earthquakes,
damaged many structures.
U.S. Geological Survey Photograph taken on June 26, 1991, by Willie Scott.
Aerial view west across Pinatubo caldera showing fumaroles and crater lake.
U.S. Geological Survey Photograph taken on May 18, 1992, by Willie Scott.
On the stability of the Earth’s
radiative energy balance: Response to
the Mt. Pinatubo eruption
J. E. Harries and J. M. Futyan
GEOPHYSICAL RESEARCH LETTERS,
VOL. 33, L23814, doi:
10.1029/2006GL027457, 2006
Mount St. Helens
Mount St. Helens in Washington is the most active volcano in the
Cascade Range. Before renewed activity in the fall of 2004, its most
recent series of eruptions had begun in 1980 when a large landslide and
powerful explosive eruption created a large crater, and ended 6 years
later after more than a dozen extrusions of lava built a dome in the
crater. Larger, longer-lasting eruptions have occurred in the volcano’s
past and are likely to occur in the future. Scientists with the U.S.
Geological Survey and University of Washington continue to closely
monitor Mount St. Helens for signs of renewed activity.
Mt. St.
Helens
ERUPTION DAY
Early in the morning on May 18, 1980, a 5.1 magnitude earthquake was recorded. The earthquake
shook the mountain and the great force of the shaking led to an instant escape of very hot ground
water and pressure. As the hot water escaped it melted the snow and ice and blew off most of the
north face of the summit! The massive explosion and force of all the pent up gases and pressure
gave way to one of the largest recorded landslides in U.S. history.
Mt. St. Helens was of no climatic significance
El Chichon, Mexico
El Chichon from the east. With a summit that is only a few hundred meters above the surrounding area,
it is lower than the surrounding non-volcanic hills. You can see the gullies that have been cut into
the 1982 pyroclastic flows. The orange color in the streams is an iron deposit that precipitates
out of water that has flowed through the pyroclastic flows.
El Chichon is the most southern and eastern volcano in Mexico. It is a small, but powerful andesitic tuff
cone and lava dome complex that occupies an isolated part of the Chiapas region far from other
Holocene volcanoes. Prior to 1982, this relatively unknown volcano was heavily forested and of no
greater height than adjacent non-volcanic peaks. The largest dome, the former summit of the volcano,
was constructed within a 1.6 x 2 kilometer summit crater, created about 200,000 years ago.
This is a view of the El Chichon caldera, formed during the very explosive eruptions of late March and early April of
1982. The caldera is about a kilometer wide and a few hundred meters deep. Prior to the 1982 eruptions the summit of
the volcano consisted of a large lava dome within a shallow caldera. There is a shallow acidic lake in the caldera, fed
entirely by ground water.
El Chichon May 1982
Mt. Agung 1963-64
Mt. Agung
Boat sailing past Mt Agung across Lombok Strait.
Mount Agung is at the left; Mount Batur,
or what remains of it, is to the right of
center
An unusual shot showing Bali's two active volcanos. In the foreground is Mt
Batur (1717 metres), in the background the more massive Mt Agung (3142
metres). In the middle distance is a high part of the Mt Batur caldera called
Mt Abang (2153 metres).
Mt Batur last erupted in 1995 and Mt Agung in 1963-64. Both are andesite
volcanos and extremely explosive.
Batur is on the island of Bali and consists
of a complex of coalesced volcanic cones
inside of two nested calderas. The calderas
formed about 50,000 and 20,000 years ago.
Space Shuttle photo.
Tambora
The 1815 eruption of Tambora was the largest eruption in historic time.