Volcanic hazard map : A tool for disaster mitigation

Abstract

A hazard map can be utilized as a means of mitigating volcanic disasters. Hazard maps are useful for assessing future volcanic disasters which are difficult to evaluate or forecast using the “deterministic” approach dealing with precise physical models of volcanoes. Instead, a “probabilistic” approach based on the past activity of a volcano can produce useful information such as those expressed in hazard maps. In recent years, hazard maps have been published on 33 active volcanoes in Japan covering most of the volcanic areas which are reckoned to be most susceptible to future eruptions. Hazard maps of Fuji volcano are outstanding in that they are the only maps authored by the national government with the scope of very wide area affected by the volcanic eruption. The maps utilized large amount of data recently collected including pyroclastic flow eruptions and numerical simulations. It is stressed that promotion of the knowledge base related to volcanic activity in general as well as specific details of the past volcanic disasters is the most essential in mitigation of disasters. Longevity of recurrence time of volcanic activity, in comparison with human life cycles makes it very difficult for general public to acquire correct knowledge of how volcanoes erupt. Coupled with bureaucratic systems in which individual officers may not stay in a fixed position of civil defense duty more than 2-3 years, the basic knowledge and preparedness of even the specialists are very meager. As Japanese islands are endowed with rich volcanic landscape and hot springs, it is suggested that we should make most of those natural environment to promote eco-tourism and recreation as well as to promote volcanic disaster mitigation by more closely understanding the nature of volcanic activity.