of ice and debris buried the village of Karmadon and filled
the surrounding basin after it slid from the Kolka Glacier.
Lakes are forming on the edges of the ice mass as it melts.
There is a threat of their sudden outburst, which would affect
villages further down the Genaldon River valley. (This photograph
was taken by Sergei Chernomorets on Oct. 6, 2002.) Larger
image (274 Kb)|
The crew of
the International Space Station observed and documented the result
of the catastrophic glacier collapse and landslide that occurred
on the northern slope of Mount Kazbek, which is one of the highest
mountains in the Caucasus range. This image centers on the peak
of Mount Kazbek, and clearly shows the surrounding glaciers and
peaks. On Sept. 20, 2002, the collapse of a hanging glacier from
the slope of Mount Dzhimarai-Khokh onto the Kolka Glacier triggered
an avalanche of ice and debris that went over the Maili glacier
terminus then slid more than 24 kilometers (15 miles). It buried
small villages in the Russian Republic of North Ossetia, killing
dozens of people. Where the ice stopped, the glacial debris flow
dammed rivers further below. Several lakes formed and one of them
flooded a village. There lakes are now threatening to burst and
form debris flows.
Glacier group is over 70 square kilometers (27 square miles) in
area. Glacier collapses have occurred in the past -- first accounts
date back to the 18th century. Exactly a hundred years ago, in 1902,
the same kind of catastrophe happened in this valley, killing 32
people. Later studies suggested that the 1902 avalanche was the
result of a glacier surge. In 1969, the Kolka Glacier surged again,
but there were no casualties and the villages were not affected.
The 1969 surge was studied by a special expedition but research
in the area stopped after the glacier stabilized. The latest data
on the September 2002 catastrophe raise doubts about the cause of
the 1902 collapse -- it is possible that the 1902 event resulted
from a similar cascade of collapses.
panoramic photo shows Maili Glacier (left) and the Kolka Glacier
terminus (center and right), including the area where huge ice
masses of Kolka Glacier slipped (center) and moved over the
Maili Glacier terminus (left). A new lake (right) formed on
the surface of the remaining mass of the Kolka Glacier after
the collapse. (The photograph was taken by Dr. Dmitry Petrakov
on Oct. 5, 2002.) Larger image (271 Kb)|
Five crew on the International Space Station -- Dr.Peggy Whitson,
Valery Korzun and Sergei Treschev -- have been photographing this
area for the Russian URAGAN project, which is studying changes in
the world's glaciers in response to global climate change. On Aug.
13, 2002, roughly one month before the glacier collapse, the station
the mountain. Although scientists have predicted the possibility
of large glacial collapses as the climate warms, at the time of
the first image, no one predicted that tragedy would strike the
mountain village of Karmadon a little more than a month later.
crew aboard Space Shuttle Atlantis photographed the glacier Oct.
17, 2002, and a new station image was taken on Oct. 19 and downlinked
about a week later. This most recent station image is very timely
for a number of reasons. First, scientists are combining the astronaut
photographs with Advanced Spaceborne Thermal Emission and Reflection
Radiometer, or ASTER, data to observe the rapid changes in a meltwater
lakes that has been formed by the collapse. An ASTER
image taken Sept. 27, showed no lake near the Kolka Glacier
Genaldon River valley is situated above the buried villages.
The bottom of the valley is now covered by ice. (This photograph
was taken by Olga Tutubalina on Sept. 22, 2001.) Larger
image (16 Kb)|
team first sighted a lake during its field trip on Oct. 5, and detected
it in the ASTER image dated Oct. 6. The lake surface area has increased
between Oct. 6 and the most recent astronaut photograph on Oct.
19. The lake is potentially dangerous, because it can produce disastrous
outburst mudflows. The succession of images shows changes in the
glacier surface and of the periglacial area during the last few
weeks. A second reason the most recent photograph from the space
station is important is its unique oblique look angle. This view
allows visualization of the three-dimensionality of the ridges and
provides enough detail to allow scientists to estimate the volume
of the initial glacier collapse. No satellites presently in orbit
can provide this combination of spatial detail and oblique look
angle. With oblique look angles and shadows, mountains appear in
dramatic relief, and this technique has been used to photograph
such areas as Mount
Everest and Dhaulagiri.
white area in the center right is the Maili Glacier terminus,
which has been buried by the ice from the Kolka Glacier. (This
photograph was taken by Olga Tutubalina on Sept. 22, 2001.)
Larger image (36 Kb)|
Space Station crewmembers are surveying glaciers around the world
using their low orbit and high-magnification lenses to get high
spatial resolution. Images such as these highlight the advantages
of human observations. The crew's ability to look obliquely to better
capture the three-dimensionality of the landscape and take advantage
of different Sun angles on the landscape provides imagery that is
both visually spectacular and easy to interpret. Crewmembers can
also select lenses and frame the specific region of interest.
is a partial view of the Kolka Glacier (center). (The photograph
taken by Sergei Chernomorets on Sept. 22, 2001.) Larger
image (19 Kb)|
The group of
Russian investigators includes Moscow State University scientists
Dr. Dmitry Petrakov, Dr. Victor Popovnin, Dr. Olga Tutubalina and
Sergei Chernomorets of the University Center for Geodynamics and
Monitoring and Dr. Lev Dessinov of the Russian Academy of Sciences.
In September 2001, the team visited the Kolka Glacier to assess
its state. After the collapse they conducted analysis of satellite
images taken by the atsronauts and provided by NASA's Johnson Space Center, and then organized a field trip to correct NASA's analysis
and gather additional information. They plan to continue monitoring
in this area using satellite images.
University's work is supported by the Russian Foundation for Basic
were provided by the Earth Sciences and Image Analysis Laboratory
at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway
to Astronaut Photography of Earth.