A NASA mission to study Alaska’s unique terrain is
providing scientists with their first detailed look at the
changing topography of one of Earth’s most active volcanic

Researchers at the Alaska Synthetic Aperture Radar
Facility, Fairbanks, have created a high-resolution digital
elevation model of Umnak Island, home to the Okmok volcano.
This model can be used to produce new, accurate geologic maps.
The most recent topographic map of the region was made in 1957
from aerial photographs. Okmok has erupted four times since
then, dramatically changing the landscape.

The Alaska scientists used data gathered in October 2000
by the Airsar instrument, designed, built and operated by
NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Airsar is a
side-looking imaging radar system carried aboard a NASA DC-8.
It collected the Alaska data as part of its PacRim 2000
Mission, which took the instrument to French Polynesia,
American and Western Samoa, Fiji, New Zealand, Australia, New
Guinea, Indonesia, Malaysia, Cambodia, Philippines, Taiwan,
South Korea, Japan, Northern Marianas, Guam, Palau, Hawaii and

After initial processing at JPL, the Airsar data were
sent to the Alaska Synthetic Aperture Radar Facility at the
Geophysical Institute at the University of Alaska Fairbanks.
Researchers there combined numerous Airsar strips of data into
a mosaic, fused it to Landsat imagery, checked its accuracy
and generated a number of data products, including the mosaic
of Umnak Island.

“Alaska needs new, accurate maps, but it continues to
fall behind,” said Rick Guritz, of the Alaska Synthetic
Aperture Radar Facility’s Science Center. “These data provide
a fresh, accurate view of a volatile environment and have been
used this summer by geologists on the volcano. Our goal is to
compare various NASA geospatial technologies for their ability
to satisfy Alaska’s needs. We are doing this in partnership
with agencies of the Alaska Department of Natural Resources.”

“The recent Airsar data have the potential to provide us
with sufficient topographic detail of the surface of Umnak
Island to produce an accurate, up-to-date geologic map of the
volcano and aid in the analysis of surface deformation that
indicates magma movement,” said Janet Schaefer, geologist of
the Alaska Volcano Observatory. “The detailed images provided
by the Alaska SAR Facility were very useful for distinguishing
geologic features such as lava flow contacts, debris avalanche
deposits, mudflow and lahar extents, stream drainage patterns,
and coastal features.” The Alaska Volcano Observatory is a
cooperative program of the United States Geological Survey,
the State of Alaska Division of Geological and Geophysical
Surveys and the University of Alaska Fairbanks Geophysical

Field work on Umnak was completed this past summer, and a
new revised geologic map of the island combining field and
airborne measurements will be created. Airsar, part of NASA’s
Airborne Science Program, is managed for NASA’s Earth Science
Enterprise by JPL. JPL is a division of the California
Institute of Technology in Pasadena. Images associated with
this release are available at
http://www.jpl.nasa.gov/images/earth/volcano. More information
on Airsar is available at http://airsar.jpl.nasa.gov/. The
Alaska Synthetic Aperture Radar Facility’s website is