An Earth-monitoring instrument aboard NASA’s Terra satellite is
keeping a close eye on a potential glacial disaster-in-the-making in Peru’s
spectacular, snow-capped Cordillera Blanca (White Mountains), the highest
range of the Peruvian Andes.

Data from NASA’s Advanced Spaceborne Thermal Emission and Reflection
Radiometer (ASTER) is assisting Peruvian government officials and
geologists in monitoring a glacier that feeds Lake Palcacocha, located high
above the city of Huaraz, 270 kilometers (168 miles) north of Lima. An
ominous crack has developed in the glacier. Should the large glacier chunk
break off and fall into the lake, the ensuing flood could hurtle down the
Cojup Valley into the Rio Santa Valley below, reaching Huaraz and its
population of 60,000 in less than 15 minutes.

“Remote sensing instruments like ASTER can serve a vital role in mountain
hazard management and disaster mapping by providing rapid access to data,
even in regions not easily accessible by humans,” explained Dr. Michael
Abrams, associate ASTER team leader at NASA’s Jet Propulsion Laboratory,
Pasadena, Calif.

“ASTER’s unique vantage point from space gives scientists another tool with
which to see early signs of potential glacial flood-burst events and to
monitor changes in glacial behavior over time. In Huaraz, Peruvian
authorities and scientists will incorporate ASTER data along with data from
ground-based monitoring techniques to better assess current conditions and
take steps necessary to reduce risks to human lives and property,” Abrams said.

Comparison images of the area and more information are available at:

http://photojournal.jpl.nasa.gov/catalog/PIA03899

Huaraz can be seen in the images’ left-center, with Lake Palcacocha in the
images’ upper right corners at the head of a valley, below the snow and
glacier cap. The left image was acquired on November 5, 2001; the right on
April 8, 2003.

Glacial flood-bursts, known by Peruvians as “aluviones,” occur periodically
when water is released abruptly from a previously ice-damned lake
alongside, within or above a glacier. The release can be caused by various
triggering events. These flood-bursts typically arrive with little or no
warning, carrying liquid mud, large rock boulders and blocks of ice.

The Rio Santa Valley is no stranger to such disasters. Since 1702, floods
caused by glaciological conditions have repeatedly caused death and
destruction in the region. One particularly devastating event in 1941
destroyed approximately one-third of Huaraz, killing an estimated 5,000 to
7,000 people. Since then, the Peruvian government has emphasized control of
the water level in Lake Palcacocha and other lakes in the region that pose
similar threats. The efforts appear to have worked; since 1972, no
destructive floods resulting from the breakout of glacial lakes have
occurred. Nevertheless, officials are still monitoring the current
situation closely.

ASTER’s broad spectral coverage and high spectral resolution is ideally
suited for monitoring dynamic conditions and changes in Earth’s landscape
over time, including glacial advances and retreats. Its 14 spectral bands
measure from the visible to the thermal infrared wavelength region, and it
can “see” at a resolution of 15 to 90 meters (about 50 to 300 feet).

ASTER provides scientists in numerous disciplines critical information used
for surface mapping and monitoring of dynamic conditions and changes over
time. Example applications include monitoring glacial advances and retreats
and potentially active volcanoes; identifying crop stress; determining
cloud morphology and physical properties; evaluating wetlands; monitoring
thermal pollution and coral reef degradation; mapping surface temperatures
of soils and geology; and measuring surface heat balance. It can also image
the same area as frequently as every other day in response to urgent
priorities.

ASTER is one of five Earth-observing instruments launched December 18,
1999, on NASA’s Terra satellite. Japan’s Ministry of Economy, Trade and
Industry built the instrument. A joint U.S./Japan science team is
responsible for validation and calibration of the instrument and the data
products.

The Terra satellite is part of NASA’s Earth Science Enterprise, a program
dedicated to understanding the Earth as an integrated system and applying
Earth System Science to improve prediction of climate, weather and natural
hazards using the unique vantage point of space.