Science Source Feb 2010
EN_90286391_0533
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The earthquake that struck China's Sichuan Province in May 2008 collapsed more than buildings. It also destroyed mountain ridges, sending avalanches of rock down their slopes. Besides directly claiming many lives, these landslides complicated rescue and cleanup efforts in the aftermath of the quake. This image, acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite, was taken on February 19, 2003. Compare it against May 23, 2008, to see the drastic changes in the terrain after the earthquake struck on May 12 . The aftershocks caused still more damage. The region shown is roughly 150 kilometers (90 miles) from the quake's epicenter. The river running through the image is Min Jiang. In these false-color images, red indicates vegetation; blue-gray indicates bare ground, buildings, and paved areas; and deep blue indicates water. Some differences between the images result from the seasons in which they were acquired. In this image, the terrain seems more rugged because the Sun's low angle cast long shadows at that time of year. Likewise, the brighter red hues in the 2008 image may result in part from more robust vegetation growing in late spring. The most dramatic difference between the images, however, is the abundance of bare-ground areas along mountain ridges resulting from landslides, which are seen in the post earthquake image. Topographic amplification strengthens an earthquake's effects on a mountaintop where the shaking is maximized. This leads to landslides that start near the top of a ridge and travel all or most of the way to the valley below. In the years between the acquisitions of these ASTER scenes, China underwent rapid industrialization and urbanization. As a result, some deforestation may have occurred in this region. Deforestation could account for some, but certainly not all, of the bare-ground areas, and it could also exacerbate the effects of the earthquake-triggered landslides. As of May 25,
2010-02-13
EAST NEWS
Science Source
NASA/Science Source
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