Wednesday, April 24, 2013

[Geology2] The Tata Sabaya stratovolcano



Tata Sabaya Volcano
acquired April 8, 2013 download large image (892 KB, JPEG, 2128x1416)

Tata Sabaya, a volcano located in the Altiplano region of Bolivia, rises to a summit elevation of 5,430 meters (17,800 feet) above sea level. While its current form is that of a youthful stratovolcano, the regional geological evidence indicates an older, eventful history.

Prior to 12,000 years ago, a large debris avalanche was formed by the collapse of the ancestral Tata Sabaya volcano. Debris from the avalanche swept into the nearby Salar de Coipasa, significantly changing its northwestern coastline. The timing of the event was obtained from tufa deposits formed on debris islands during a high stand of the Coipasa lake. The sequence illustrates the geological principle of crosscutting, in that the debris avalanche had to have occurred before the tufa deposits were formed in the lake.

The Tata Sabaya stratovolcano is located at image center in this photograph from the International Space Station. Several young lava flows are visible on the northwestern and western flanks of the volcano. Peaks visible to the northeast and southwest appear to be volcanoes as well, but unlike Tata Sabaya, there is no record of recent activity from either of them, according to the Smithsonian National Museum of Natural History's Global Volcanism Program.

As the climate of the Altiplano became more arid and the Coipasa Lake shrank, much of the hummocky terrain of the debris avalanche became exposed (an area of more than 300 square kilometers, or 116 square miles). The hummocky terrain is clearly visible on the left side of the image. White salt deposits of the salar surround many of the individual hummocks, making them "islands" once again.

Astronaut photograph ISS035-E-18006 was acquired on April 8, 2013, with a Nikon D3S digital camera using a 400 mm lens, and is provided by the ISS Crew Earth Observations experiment and the Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 35 crew. The image in this article has been cropped and enhanced to improve contrast. Lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, Jacobs/ESCG at NASA-JSC.

http://earthobservatory.nasa.gov/IOTD/view.php?id=80945&src=eoa-iotd
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