This detailed astronaut 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
volcanoes formed by interwoven layers of lava 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 Cañadas
caldera. A caldera is a large collapse depression usually formed when a
major eruption completely empties the magma chamber underlying a
volcano. The last eruption of Teide occurred in 1909.
Sinuous flow levees marking individual
lava flows are 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 (gas and
smoke) activity within the Las Cañadas caldera and along the
northwestern flanks of the volcano were observed in 2004. Monitoring of
the volcano to detect renewal of activity is ongoing.
Astronaut photograph ISS020-E-21140
was acquired on July 15, 2009, with a Nikon D3 digital camera fitted
with an 800 mm lens, and is provided by the ISS Crew Earth Observations
experiment and Image Science & Analysis Laboratory, Johnson Space
Center. The image was taken by the Expedition 20 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 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, NASA-JSC.