image (437 Kb)
is a high volcano that lies at the south end of the Tibesti Mountains
in the central Sahara Desert in northern Chad. The volcano is one
of several in the Tibesti massif, and reaches 3,415 meters (11,204
feet) in altitude, rising 2.3 kilometers (1.4 miles) above the surrounding
sandstone plains. The volcano is 65 kilometers (40.4 miles) wide.
image is an anaglyph stereo image of Elysium Mons on Mars. See
direct comparison of Emi Koussi and Elysium Mons. (photo
by Malin Space Systems)|
This view of
the Emi Koussi caldera was taken with an 800-mm lens Nov. 21, 2002.
It is detailed to the point that it doesn't include the entire 10-kilometer
(6.2-mile) diameter of the caldera, but reveals individual lava
strata within the walls of the summit cliffs. Nested within the
main caldera is a smaller crater that contains white salts of a
dry lake at its lowest point. Here too, strata are visible in the
walls of the smaller crater. The smaller crater is surrounded by
a region of darker rocks -- a geologically young dome of lava studded
with several small, circular volcanic vents.
has been used as a close analog to the famous Martian volcano Elysium
One of the most important morphological differences between volcanoes
on Mars and Earth is the widespread furrowing of the surface due
to flowing water on terrestrial volcanoes. The furrows are shallow
valleys. Larger channels have a different origin. Major channels
can be seen on volcanoes on both planets and indicate low points
in caldera rims where lava spilled out of pre-collapse craters (top
left and bottom).
was 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.