2000 Volume 41 Issue 3 Pages 150-154_2
Phreatomagmatic eruption has occurred at the western flank of Usu volcano, southwestern Hokkaido, northern Japan, at 31 March 2000. Surrounding towns have been seriously damaged and refuge has been prolonged for three months, because the eruptive vents have formed close to residence category of surrounding towns and the main traffic routes, and the eruption has involved remarkable crustal movement. Serious damages by crustal deformations (such as many pressure ridges, cracks, buckling deformations of the kerbstones, and landslide-like surface movement), uplift, ballistic ejecta, mudflow, earthquakes occurred near the volcano. Important national routes (national roads, railways, and the highway), houses, buildings, water pipes, transmission lines, retaining walls, bridges have been damaged or destroyed. On the other hand, sites of the vents and the time of eruption have been predicted by scientists based on the sites of the crustal movement and the earthquake foci. Hazard map of the volcano was corrected based on the observation results and refuge has been done before the eruption. So no victim occurred until now. This case indicates that appropriate hazard map and the effective utilization of it can decrease the disaster.