Geotour for disaster prevention holding in Unzen Volcanic Area Global Geopark

Unzen Volcanic Area Global Geopark is one of the four Global Geoparks in Japan highlighting the impressive scenery and deposits produced by the Unzen Volcano. During 1990-1995, serious disasters resulted from the eruption of Unzen Volcano (named as “Heisei Eruption”) in Shimabara Peninsula. The eruption lasted for 5 years and led to a decline in population and tourist numbers, thereby causing severe economical losses. Local people, however, have learned from these disasters and now attempt to make a use of their experience for promotion of the Geopark.

The Heisei Eruption was characterized by the extrusion of viscous magma (dacite) and its growth as a lava dome [1]. The growth of the dome was described in detail and its record has become a valuable academic observation case. The lava dome partially collapsed during its growth and caused repeated pyroclastic flows (more than 9,000 times). Strong hot ash clouds (pyroclastic surge) accompanied with large pyroclastic flows killed 44 persons and burned many houses including a school building. Moreover, when heavy rains occurred, parts of the pyroclastic flow deposits were washed down by rainwater and flooded the river as large debris flows. As a result, many houses and fields were buried by the flows and many residents lost their property due to these disasters.

It is important that residents in the Geopark area share their knowledge about Unzen Volcano as they should learn to coexist with an active volcano. In order to pass experiences of these disasters over to next generation, the burnt school building and some houses destroyed by the eruption were preserved just as they were at that time (Fig. 1). Now, these remnants became major geosites of our Geopark and have strongly appealed not only to local people but also visitors for a true appreciation of a volcanic eruption and the associated disasters. Especially, they give effective results for school children who were born after the Heisei Eruption, contrary to those school children (11-12 years old) who were using this building at the time of the eruption but did not understand what was happening. We are convinced that organising such geotours contributes to disaster prevention for the local population and has become a significant pillar to heritage-based sustainable development.

Fig. 1. Geosites consisting of remains after the Heisei Eruption. (A) building of the elementary school burned by strong hot ash cloud, (B) destroyed houses by debris flows. The mountain shown by arrows is the lava dome generated by the Heisei Eruption.