Llullaillaco volcano on the Argentina-Chile border is featured in this image photographed by an Expedition 22 crew member on the International Space Station. The summit of Llullaillaco volcano has an elevation of 6,739 meters above sea level, making it the highest historically active volcano in the world. The current Llullaillaco stratovolcano — a typically high, cone-shaped volcano built from successive layers of thick lava flows and eruption products like ash and rock fragments — is built on top of an older stratovolcano. The last explosive eruption of the volcano occurred in 1877 based on historical records. This detailed photograph of Llullaillaco illustrates an interesting volcanic feature known as a coulee (top left). Coulees are formed from highly viscous, thick lavas that flow onto a steep surface; as they flow slowly downwards, the top of the flow cools and forms a series of parallel ridges oriented at 90 degrees to the direction of flow (somewhat similar in appearance to the pleats of an accordion). The sides of the flow can also cool faster than the center, leading to the formation of wall-like structures known as flow levees (center).
An Expedition 31 crew member aboard the International Space Station, flying approximately 240 miles above Earth, recorded a series of images of the current wild fires in the southwestern United States. These particular fires, of unknown cause, are burning at the south end of the Wyoming Range in southwestern Wyoming, and have affected 17,000 acres. The fires have produced two major smoke plumes (center) that dominate the image. The fires are occurring 120 miles due south of Yellowstone Lake which appears as an irregular blue shape (upper right –if the image is oriented with north toward the top right corner). Utah’s Great Salt Lake (image far left) is about 120 miles away. Winds transport the smoke in a northeasterly direction: the plumes can be seen to cross the Wind River Range (center), blowing directly toward the Big Horn Mts., which appear as a dark, curved feature (lower right). This 180mm image spans a wide area from northern Utah (left) to northeastern Montana (right).
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