| The STS-055 crew documented outgassing by Colima Volcano in Mexico. The red and pink tones of the color infrared photograph (fig. 3) distinguish the dense vegetation on the flanks of the volcano from the thinner vegetation in the surrounding fields. A steam plume drifts toward the southwest (best seen along the bottom of the frame) from the 4060-m blackened summit; the white streaks near the summit are recent landslides. The last major eruption of Colima was in 1913, with previous eruptions recorded in 1585, 1606, 1622, 1818, and 1890, but geologists speculate that small, quieter eruptions must occur fairly frequently. The current episode started about March 1, 1991, with avalanche activity, followed by lava extrusion and ash emission. The most recent eruption was an explosion on July 21, 1994, which deposited a 2-mm ashfall over 380 sq. km west of the volcano.
 Figure 3: Colima Volcano. In this color infrared view of Colima Volcano, south of Guadalajara, Mexico, the most active volcano in the country, the dark red tones indicate a thick forest canopy on the flanks of the volcano, while the pink colors indicate thinner vegetation cover in the nearby agricultural fields. This northeast-looking photograph captures Colima in action, with a steam plume drifting southwest (toward the bottom of the frame). [NASA photograph STS055-84-117. (See also STS031-84-030 and STS039-75-102 for other views of Colima.)]
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Among other significant volcanic activity documented by the STS-55 crew was the redistribution of ash from an eruption of Lascar Volcano in the Altiplano of Chile, which occurred on April 20, 1993, during the week after the landing of STS-56 and before the launch of STS-55. (See STS61C-32-091 for the appearance of Lascar before this eruption.) Several plumes of blowing material can be seen in this photograph (fig. 4), taken on May 4. All the plumes originate downwind of Lascar, the peak at the head of a gray triangle of ash. It seems most likely, therefore, that the blown material is dust-sized particles of ash that was deposited on the high Andean plateau by Lascar during the April 20 eruption. The large, dense, V-shaped plume in this frame is about 40 km long. It is blowing eastward from a point about 100 km southeast of Lascar. On May 10, images from the AVHRR sensor on the environmental satellite NOAA-11 showed dust from these parts of the Altiplano reaching the lowlands hundreds of kilometers to the east. (See also STS055-102-076.) Only 2 months later, the STS-57 crew photographed this region and found that the wind had removed almost all the unconsolidated ash east of Lascar (see STS057-80-084). |
Figure 4: Altiplano Ash/Dust Plume. This photograph shows a large, dense, V-shaped volcanic ash plume blowing eastwards from a depositional point near Lascar Volcano, which erupted on April 20, 1993, only a few days before this photo was taken over northern Argentina, on May 4 at 19 hours, 10 minutes, 38 seconds GMT. [NASA photograph STS055-151-058]
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