Teide Volcano, Spain (NASA, International Space Station Science, 7/15/09)

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Teide Volcano, Spain (NASA, International Space Station Science, 7/15/09)




Image by NASA's Marshall Space Flight Center

Teide Volcano on the Canary Islands of Spain is featured in this image photographed by an Expedition 20 crew member on the International Space Station. This detailed photograph features two stratovolcanoes - Pico de Teide and Pico Viejo - located on Tenerife Island, part of the Canary Islands of Spain. Stratovolcanoes are steep-sided; typically conical structures formed by interlayered lavas and fragmented rock material from explosive eruptions. Pico de Teide has a relatively sharp peak, whereas an explosion crater forms the summit of Pico Viejo. The two stratovolcanoes formed within an even larger volcanic structure known as the Las Canadas caldera - a large collapse depression typically formed when a major eruption completely empties the underlying magma chamber of a volcano. The last eruption of Teide occurred in 1909. NASA scientists point out sinuous flow levees marking individual lava flows. The scientists consider the flow levees as perhaps the most striking volcanic features visible in the image. Flow levees are formed when the outer edges of a channelized lava flow cool and harden while the still-molten interior continues to flow downhill - numerous examples radiate outwards from the peaks of both Pico de Teide and Pico Viejo. Brown to tan overlapping lava flows and domes are visible to the east-southeast of the Teide stratovolcano. Increased seismicity, carbon dioxide emissions, and fumarolic activity within the Las Canadas caldera and along the northwestern flanks of the volcano were observed in 2004. Monitoring of the volcano to detect renewal of activity is ongoing.

Image Credit: NASA

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More about the Crew Earth Observation experiment aboard the International Space Station:
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Harrat Khaybar, Saudi Arabia (NASA, International Space Station Science, 03/31/08)




Image by NASA's Marshall Space Flight Center

Harrat Khaybar, Saudi Arabia is featured in this image photographed by an Expedition 16 crewmember on the International Space Station. The western half of the Arabian peninsula contains not only large expanses of sand and gravel, but extensive lava fields known as haraat (harrat for a named field). One such field is the 14,000-square kilometer Harrat Khaybar, located approximately 137 kilometers to the northeast of the city of Al Madinah (Medina). According to scientists, the volcanic field was formed by eruptions along a 100-kilometer long north-south linear vent system over the past 5 million years; the most recent recorded eruption took place between 600 - 700 A.D. Harrat Khaybar contains a wide range of volcanic rock types and spectacular landforms, several of which are represented in this view. Jabal al Quidr is built from several generations of dark, fluid basalt lava flows; the flows surround the 322--meter high stratovolcano (Jabal is translated as "mountain" in Arabic). Jabal Abyad, in the center of the image, was formed from a more viscous, silica-rich lava classified as a rhyolite. While Jabal al Quidr exhibits the textbook cone shape of a stratovolcano, Jabal Abyad is a lava dome -- a rounded mass of thicker, more solidified lava flows. To the west (top center) is the impressive Jabal Bayda'. This symmetric structure is a tuff cone, formed by eruption of lava in the presence of water. This leads to the production of wet, sticky pyroclastic deposits that can build a steep cone structure, particularly if the deposits consolidate quickly. White deposits visible in the crater of Jabal Bayda' (and two other locations to the south) are formed from sand and silt that accumulate in shallow, protected depressions. The presence of tuff cones -- together with other volcanic features indicative of water -- in the Harrat Khaybar suggest that the local climate was much wetter during some periods of volcanic activity. Today, however, the regional climate is hyperarid -- little to no yearly precipitation -- leading to an almost total lack of vegetation.

Image credit: NASA

Read full caption:
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More about the Crew Earth Observation experiment aboard the International Space Station:
www.nasa.gov/mission_pages/station/science/experiments/CE...

More about space station science:
www.nasa.gov/mission_pages/station/science/index.html

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