Earth Observations taken by the Expedition 18 Crew

ISS018-E-035716 (24 Feb. 2009) --- Minchinmavida and Chaiten Volcanoes in Chile are featured in this image photographed by an Expedition 18 crewmember on the International Space Station. The Andes mountain chain along the western coastline of South America includes numerous active stratovolcanoes. The majority of these volcanoes are formed, and fed, by magma generated as the oceanic Nazca tectonic plate moves northeastward and plunges beneath the less dense South American continental tectonic plate (a process known as subduction). The line of Andean volcanoes marks the approximate location of the subduction zone. This astronaut photograph highlights two volcanoes located near the southern boundary of the Nazca ? South America subduction zone in southern Chile. Dominating the scene is the massive Minchinmavida stratovolcano at center. An eruption of this glaciated volcano was observed by Charles Darwin during his Galapagos Island voyage in 1834; the last recorded eruption took place the following year. The white, snow covered summit of Minchinmavida is blanketed by gray ash erupted from its much smaller but now active neighbor to the west, Volcan (volcano) Chaiten. The historically inactive Chaiten volcano, characterized by a large lava dome within a caldera (an emptied and collapsed magma chamber beneath a volcano) roared back to life unexpectedly on May 2, 2008, generating dense ash plumes and forcing the evacuation of the nearby town of Chaiten. Volcanic activity continues at Chaiten, including partial collapse of a new lava dome and generation of a pyroclastic flow several days before this photograph was taken. A steam and ash plume is visible extending to the northeast from the eruptive center of the volcano.