After more than a decade of inactivity, Mount St. Helens came to
life in September 2004. On Sept. 24, to help geologists and
vulcanologists assess the risk of an eruption, NASA flew a
low-altitude aircraft carrying the MODIS/ASTER Airborne Simulator
(MASTER) directly over the volcano to obtain high-resolution images
of its caldera. The images above show the caldera in spectacular
detail.
The image on the left, collected by DigitalGlobe’s QuickBird
satellite on Oct. 2, shows Mount St. Helens in natural color on the
same day scientists issued an alert that the volcano could erupt any
time. The scene on the right was produced using MASTER’s thermal
infrared detectors. The bulge in the caldera’s center is the lava
dome, which has been growing in size due to the upward pressure of
magma.
After these images were obtained, Mount St. Helens emitted several
plumes of ash and steam, as if to validate geologists’ warnings. On
Oct. 6, geologists lowered the alert level—although officials say an
eruption could occur with little warning. However, geologists don’t
anticipate anything similar to the May 18, 1980, blast that killed
57 people, blew 1,300 feet off the top of the peak and paralyzed
much of the northwestern United States.
Airborne NASA image courtesy: Jeff Myers and Rose Dominguez, Master
Project, Ames Research Center and the Jet Propulsion Laboratory.
