On February 19, 2000, Space Shuttle Endeavour passed over the highly active
and dangerous volcanic zone of the Andes in Equador. Endeavour was mapping
elevations on most of the Earths land surface during the
Shuttle Radar Topography Mission (SRTM). There have been
more than 50 eruptions of Mt. Cotopaxi alone since 1738. With its height
of 5,897 meters it is more than 3,000 meters higher than the
surroundings. The base of this stratovolcano has a width about 23 km.
The digital elevation model acquired by SRTM, with its resolution of 25 m x 25 m, is so
rich in detail that you can even make out an inner crater with a
diameter of 120 m by 250 m inside the outer crater (800 m x 650 m). Blue and green correspond to the
lowest elevations in the image, while beige, orange, red, and white represent increasing elevations.
Numerous valleys formed by powerful Lahars (mudflows) are prominent in
the digital elevation model. Lahars can cause severe damage even 300 km away from the
volcano. This poses a high risk to the local population, their
settlements and fields. Interferometry is especially useful in
monitoring such dangerous volcanoes. Highly accurate observations of
changes in volcanoes from space can provide vital parameters for early
warning systems, without risk to the lives of scientists. An operational
system, though, would rely on a system of interferometric sensors to map
on a regular basis.