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sc-unzen.txt
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1995-02-23
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SPACEBORNE IMAGING RADAR-C/
X-BAND SYNTHETIC APERTURE RADAR
(SIR-C/X-SAR)
PHOTO CAPTION P-45150
January 26, 1995
Unzen volcano, Japan
This is a space radar image of the area around the Unzen
volcano, on the west coast of Kyushu Island in southwestern
Japan. Unzen, which appears in this image as a large
triangular peak with a white flank near the center of the
peninsula, has been continuously active since a series of
powerful eruptions began in 1991. The image was acquired by
the Spaceborne Imaging Radar-C/X-band Synthetic Aperture
Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on
its 93rd orbit on April 15, 1994. The image shows an area
41.5 kilometers by 32.8 kilometers (25.7 miles by 20.3
miles) that is centered at 32.75 degrees north latitude and
130.15 degrees east longitude. North is toward the upper
left of the image. The radar illumination is from the top
of the image. The colors in this image were obtained using
the following radar channels: red represents the L-band
(vertically transmitted and received); green represents the
average of L-band and C-band (vertically transmitted and
received); blue represents the C-band (vertically
transmitted and received). Unzen is one of 15 "Decade"
volcanoes identified by the scientific community as posing
significant potential threats to large local populations.
The city of Shimabara sits along the coast at the foot of
Unzen on its east and northeast sides. At the summit of
Unzen a dome of thick lava has been growing continuously
since 1991. Collapses of the sides of this dome have
generated deadly avalanches of hot gas and rock known as
pyroclastic flows. Volcanologists can use radar image data
to monitor the growth of lava domes, to better understand
and predict potentially hazardous collapses.
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Spaceborne Imaging Radar-C and X-band Synthetic Aperture
Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet
Earth. The radars illuminate Earth with microwaves, allowing
detailed observations at any time, regardless of weather or
sunlight conditions. SIR-C/X-SAR uses three microwave
wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3
cm). The multi-frequency data will be used by the
international scientific community to better understand the
global environment and how it is changing. The SIR-C/X-SAR
data, complemented by aircraft and ground studies, will give
scientists clearer insights into those environmental changes
which are caused by nature and those changes which are
induced by human activity. SIR-C was developed by NASA's
Jet Propulsion Laboratory. X-SAR was developed by the
Dornier and Alenia Spazio companies for the German space
agency, Deutsche Agentur fuer Raumfahrtangelegenheiten
(DARA), and the Italian space agency, Agenzia Spaziale
Italiana (ASI), with the Deutsche Forschungsanstalt fuer
Luft und Raumfahrt e.V.(DLR), the major partner in science,
operations and data processing of X-SAR.
#####