Detection of volcanic smoke and ash-fall area at Volcano Aso, from Landsat MSS data.

Volcano Aso had frequent eruptions from 1979 through 1980, and a large amount of volcanic smoke and ash was emitted from its crater. The area spread over by the volcanic smoke and the area covered by the volcanic ash of this period were investigated by the optical analysis method of the Landsat MSS image. Volcanic smoke and ash-fall area were clearly detected from the Landsat MSS image. Their detectable area was seen to change with the transition of volcanic activity, and the maximum extension of volcanic smoke was about 70 km from the crater, and that of volcanic ash-fall area was about 10 km around the crater. By observation from the Landsat, it is possible to get information on the wide horizontal distribution of volcanic smoke or ash-fall, and the data from the Landsat are very useful for volcano observation.