Mt. Usu, located at Abuta-Cho in Hokkaido, is one of most active volcanoes in Japan and repeated eruptions periodically. Large quantities of volcanic ash are released with the eruptions, and the crop damages are spreading by the ash falls. If agricultural fields become unsuitable due to fallen ashes, it is necessary to recover of the fields. For the determination of the damages for the crops and the agricultural fields, there are urgent needs to quickly create contour maps of the thickness of the ash fall in order to show the distribution of falling volcanic ash by volcanic eruptions

For this purpose, we used remote sensing data because of producing the contour maps of the ash falls safely and quickly.

Following the eruption of Mt. Usu between August 7 and August 14, 1977, aerial MSS observed Mt. Usu and surrounding area on August 21 1977 by the Japan Foundation for Shipbuilding Advancement as a National Land Academic Diagnostic Project, and LANDSAT/MSS data was acquire on September 17. Land-based spectral observation, ash distribution surveys and damage survey of agricultural crop data are performed nearly same time. Using the remote sensing data and ground survey data, an integrated research for volcanic ash distribution was performed.

1) We were able to clearly distinguish the fallen ash areas in the color composite images obtained from aerial MSS with RGB = near infrared, red and green, and RGB = thermal infrared, near infrared and green and images obtained from LANDSAT/MSS with RGB = near infrared, red and green.

2) We attained a high correlation of r=0.83 between the operational value of the LANDSAT/MSS near-infrared and green bands and the thickness of the ash falls.

3) Spectral measurement data of the volcanic ashes on different eruption times indicated the each characteristic of mineral contents.

The damage by the eruption of Mt. Usu in 1977 caused 11.8 billion Yen as agricultural damage. In Japan, this report was the first case of agricultural damage research using remote sensing data. The research demonstrated the effectiveness of remote sensing technology, and promoted the use of remote sensing for future disaster surveys.

For identification of the volcanic ashes and thickness of the ash, we obtained almost same results using LANDSAT/MSS and using airborne MSS data, and it was effective to use satellite remote sensing data for surveys agricultural damage by ash of volcano eruption.