Once it had become a mud flow, it flowed along the river channel to a hot springs hotel (Komanoyu) at an elevation of 800 m below the source of the debris flow. Seven lives, including two persons who were missing for an entire year before being discovered, were lost in the hotel. Since the river channel, which should have been the natural path of the mud flow, was buried by the landslide at the opposite bank side of the hotel, due to the earthquake, the mud flow changed its course and proceeded in the direction of the hotel. The mud flow reached the hotel about 10 min after the earthquake, according to the testimony of one survi- vor. The travel distance was about 5 km from the source point to the hotel along the river, as shown in Fig. 9. Therefore, the average velocity of the debris flow is estimated to have been about 30 km/h. The hot springs hotel is shown in Photo 1, before and after the event. The second floor of a two-story house remained. The house moved about 50 m upstream and rotated. Only two very tall trees, which were in front of the house, were left. A large number of gigantic trees and large rock masses, all covered with mud, were included in the deposits that piled up at the hotel site. The mud deposits were so soft that it was impossible to walk on them after this event. We were able to reach the site four days later with the support of the Self-Defense Force of the Japanese Government.