Tuesday, January 25, 2011

NASA ISS Image: Landslides in Brazil


At least 809 people have now died in what some news outlets and government agencies are calling the worst natural disaster in Brazil’s history.

Following unusually persistent rain in early January and an extreme rainfall event on January 11-12, large swaths of the Brazilian states of Sao Paolo, Rio de Janeiro, and Santa Catarina were devastated by mud sliding off the soaked hills and by rivers overflowing or carving up their soft banks.

After weeks of cloud cover, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite finally collected the top image of the mountainous region northeast of Rio de Janeiro on January 18, 2011. The lower image was taken by the same instrument on February 13, 2003.

In this near-infrared image, vegetation-covered land appears red, concrete and building materials appear gray, clouds are white, and bare land tends to be sandy brown (though some exposed rock surfaces appear much darker).

A comparison of the 2011 and 2003 images, combined with news and scientific accounts, reveals the likely tracks of light-brown mudslides marked in the image above.

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