8.+Volcanoes



Above are two false-color Landsat satellite images of Mount St. Helens and vicinity. The first image is from August 29, 1979. Just months later, in March 1980, the ground began to shake. Red indicates vegetation; patches of lighter color are where the region was logged. The second image is from September 24, 1980, four months after the large eruption on May 18. The relics of the eruption are everywhere. The mountain’s northern flank has collapsed, leaving a horseshoe shaped crater. Rock and ash have blown over 230 square miles. Dead trees are floating in Spirit Lake and volcanic mudflows clog the rivers. A more recent image shows that vegetation has begun to colonize at the farther reaches of the area affected by the eruption.