by neufer » Sun May 22, 2011 1:31 pm
ttp://earthobservatory.nasa.gov/IOTD/view.php?id=50666 wrote:
<<Spanning about 22 kilometers (14 miles), Valles Caldera in New Mexico was formed from the collapse of a magma chamber following ancient volcanic eruptions. The Enhanced Thematic Mapper Plus on Landsat 7 satellite captured this natural-color image of the area on May 22, 2002. Plants have colonized parts of the caldera, which is surrounded by a network of valleys. The city of Los Alamos lies to the east.
Valles Caldera is a complex formation resulting from two high-volume eruptions that occurred during the Pleistocene Epoch. Eruptions about 1.7 million and 1.2 million years ago pushed up magma that was rich with water and granite. When the magma broke through overlying rock layers, its water content turned to steam, driving powerful eruptions that buried the surrounding area in layers of volcanic ash—hundreds of meters thick in some places. As ash and steam billowed overhead, magma under the surface dwindled. In the eruption 1.2 million years ago, a giant rock plug descended into the magma chamber, leaving steep rock walls around its perimeter. Landslides toward the chamber quickly followed. Over thousands of years, however, the caldera floor slowly rose. Today, hot springs and fumaroles persist at Valles Caldera. The volcanic ash that sprayed over the landscape during the Pleistocene later hardened into the Bandelier Tuff. Parts of this porous volcanic rock later became home to Ancestral Pueblo people who carved
cavates. Some of these ancient dwellings are now preserved at Bandelier National Monument.>>
http://asterisk.apod.com/viewtopic.php? ... KI#p133551
http://www.planetaryexploration.net/jupiter/io/loki.html wrote:
<<
Loki is the most powerful volcano in the solar system, and consistently emits more heat than all of Earth's volcanoes combined. Loki has an enormous caldera, larger than the state of Maryland, which is continually flooded with lava. Lava temperatures recorded at the Loki hot spot are similar to those of basaltic lavas on Earth.
Active lava and lava that is still cooling cover the floor of the Loki caldera and surround a light-colored island. With the exception of a narrow crack in the center of the island where high temperatures indicate volcanic activity, the rest of the island appears to be cold. Current volcanic activity can be seen in this temperature map. The yellow regions correspond to temperatures of about 87 degrees Celsius, and the red areas record temperatures of about 157 degrees Celsius. The hottest temperatures correspond to the white areas. Here temperatures reach upwards of 567 degrees Celsius.
Scientists are still trying to determine what kind of volcano Loki is. The high temperatures on the western edge of the caldera support the idea that it is an active lava lake with molten material beneath the crust. In volcanic calderas on Earth, such as Hawaii's Kilauea volcano, the crust that forms on the surface as the lava cools tends to drift outward, eventually hitting the caldera wall. Upon striking the wall, the crust breaks up causing hotter material from below the surface to be exposed. >>
[quote=" ttp://earthobservatory.nasa.gov/IOTD/view.php?id=50666"]
[float=right][img3="Valles Caldera"]http://earthobservatory.nasa.gov/images/imagerecords/50000/50666/vallecaldera_etm_2002142.jpg[/img3][/float]
<<Spanning about 22 kilometers (14 miles), Valles Caldera in New Mexico was formed from the collapse of a magma chamber following ancient volcanic eruptions. The Enhanced Thematic Mapper Plus on Landsat 7 satellite captured this natural-color image of the area on May 22, 2002. Plants have colonized parts of the caldera, which is surrounded by a network of valleys. The city of Los Alamos lies to the east.
Valles Caldera is a complex formation resulting from two high-volume eruptions that occurred during the Pleistocene Epoch. Eruptions about 1.7 million and 1.2 million years ago pushed up magma that was rich with water and granite. When the magma broke through overlying rock layers, its water content turned to steam, driving powerful eruptions that buried the surrounding area in layers of volcanic ash—hundreds of meters thick in some places. As ash and steam billowed overhead, magma under the surface dwindled. In the eruption 1.2 million years ago, a giant rock plug descended into the magma chamber, leaving steep rock walls around its perimeter. Landslides toward the chamber quickly followed. Over thousands of years, however, the caldera floor slowly rose. Today, hot springs and fumaroles persist at Valles Caldera. The volcanic ash that sprayed over the landscape during the Pleistocene later hardened into the Bandelier Tuff. Parts of this porous volcanic rock later became home to Ancestral Pueblo people who carved [url=http://www.flickr.com/photos/bandeliernps/4838419868/]cavates[/url]. Some of these ancient dwellings are now preserved at Bandelier National Monument.>>[/quote]
http://asterisk.apod.com/viewtopic.php?f=9&t=21366&p=133551&hilit=LOKI#p133551
[quote=" http://www.planetaryexploration.net/jupiter/io/loki.html"]
[float=right][img]http://www.planetaryexploration.net/jupiter/io/images/cll_loki_00320.jpg[/img]
[img]http://www.planetaryexploration.net/jupiter/io/images/loki_isle_temp_pia02595.jpg[/img][/float]
<<[b][color=#FF0000]Loki is the most powerful volcano in the solar system, and consistently emits more heat than all of Earth's volcanoes combined. Loki has an enormous caldera, larger than the state of Maryland, which is continually flooded with lava. Lava temperatures recorded at the Loki hot spot are similar to those of basaltic lavas on Earth.[/color][/b]
Active lava and lava that is still cooling cover the floor of the Loki caldera and surround a light-colored island. With the exception of a narrow crack in the center of the island where high temperatures indicate volcanic activity, the rest of the island appears to be cold. Current volcanic activity can be seen in this temperature map. The yellow regions correspond to temperatures of about 87 degrees Celsius, and the red areas record temperatures of about 157 degrees Celsius. The hottest temperatures correspond to the white areas. Here temperatures reach upwards of 567 degrees Celsius.
Scientists are still trying to determine what kind of volcano Loki is. The high temperatures on the western edge of the caldera support the idea that it is an active lava lake with molten material beneath the crust. In volcanic calderas on Earth, such as Hawaii's Kilauea volcano, the crust that forms on the surface as the lava cools tends to drift outward, eventually hitting the caldera wall. Upon striking the wall, the crust breaks up causing hotter material from below the surface to be exposed. >>[/quote]