At 1:07 pm on March 31, there was an explosion of magma steam from the foot of Nishi-yama.
The steam rose 3,500 meters above the crater, volcanic rocks were spewed around the area, and volcanic ash fell on the northeast side. The following day, new craters formed on the foot of Nishi-yama and Konpira-yama (mountain), which is located near to the hot spring area.
National Highway 230, which passes through the series of Nishi-yama craters, was destroyed by warps in the ground and faults, making the highway impassable. The steam released from the Konpira-yama (mountain) created hot mud slides, which flowed down to the Toyako Onsen area and destroyed two bridges that hung over Nishi-yama river. Many houses in the vicinity of the crater were destroyed by volcanic rocks and ground movement, and roads over a large area were destroyed or damaged by deformations in the ground.
On March 29th, the Japan Meteorological Agency released an emergency volcano alert, and it was possible to evacuate the more than ten thousand residents of the three surrounding cities of Sobetsu-cho, Abuta-cho (at that time), and Date-shi, before the eruption.
The Emergency volcano alert is normally an alert of an eruption that could cause loss of life, but this was the first example of an alert before the eruption.
Mount Usu is a volcano with eruptions that are relatively easy to predict. The cycle of eruptions is short and stable, and many local residents have experienced the last two eruptions, and some have even experienced the past three eruptions. There is a strong awareness (among residents) that gsince we make a living through the gift of the volcanic activity of Mount Usu, such as the hot springs, it is only natural that we have to deal with an eruption once every thirty years.h A disaster prevention map for the neighboring cities has been created, children are given regularly lessons on volcanoes, and there is appropriate evacuation guidance to avoid dangerous areas. These are some of the factors that have minimized damage.
The 2000 Mount Usu eruption caused substantial damage since it occurred near the hot spring area, but there were no fatalities since the residents quickly evacuated before the eruption, which was said to be possible because of the volcano disaster prevention map that was created in advance. The map shows areas that may be damaged by an eruption, and on account of its success with Mount Usu, volcano disaster prevention maps have been created for volcanic areas throughout Japan.