On August
17th 1999 an earthquake of magnitude 7.4 on the Richter scale caused extensive
damage and loss of life in the urban areas around Izmit in north
west Turkey. This image is a composite of two black and white images, one
recorded on 7th August 1999 and the other on 24th September 1999. The colours
in the image indicate change. Orange largely highlights severely damaged buildings
and areas where debris has been deposited during the rescue operation. Blue
indicates areas submerged beneath sea level as a result of the earth's movement
during the earthquake. Time Difference images such as this can be used to
monitor
changes from various forms of natural disaster or from military conflict.
Seattle, Washington, USA (right)
This image of Washington D.C., with the White House in the top-right and the
Washington Monument on the left (north is to the right), was recorded on 30th
September 1999 by Space Imaging's IKONOS-2 satellite. This was the first image
to be commercially available with a ground-sampling interval (pixel size) of
1
metre. With a pointable sensor, image acquisition attempts can be made in as
little as 1-3 days (cloud cover permitting). This level of resolution enables
satellite imagery to be used as a data source for the wide-range of applications
that otherwise requires expensive aerial surveys to be flown. In addition data
can readily be acquired for projects in remote regions of the world and areas
where access is restricted. The IKONOS-2 satellite also has a 4m resolution,
4
band colour sensor, which can be used to add colour to the 1m resolution data.
