This ASTER thermal-infrared composite image (left), the first high spatial
resolution multispectral thermal infrared data from satellite, is of an area in
the Afar Triangle. It shows color
variations which are mainly due to rock and soil composition differences;
temperature differences are expressed as brightness variations. Areas
shown in the red hues on the left and right sides are probably underlain by
rocks with high silicon-dioxide content, whereas those areas appearing
white and lavender in the central part are a more mafic composition,
dominantly basaltic lava flows and cinder cone deposits. The dark areas
within the complex of basaltic rocks are mainly domes, which are highly
fractured. The multispectral thermal-infrared capability of ASTER will permit
compositional determinations that are not possible in the shorter
wavelength regions. The ten very bright pixels in the lower center of the
image show high temperatures of molten lava in the summit crater of the
active Erta Ale volcano. A coregistered SPOT images is shown to the right.
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