Volcanic threat in developing countries of the Asia-Pacific region: probabilistic hazard assessment, population risks, and information gaps

The importance of disaster reduction has gained increased awareness within the international development community and thereby highlighted a need for a preliminary assessment of natural hazard risk in developing countries of the Asia-Pacific, including that for volcanic eruption. In this paper, we present a key component of such an assessment, which involved qualifying the frequency and potential consequences of large-Volcanic Explosivity Index of four or more-volcanic eruptions. The frequencies of large eruptions from volcanoes grouped by region were determined from frequency-magnitude plots using data provided by the Smithsonian Institution's Global Volcanism Program. However, calculated frequencies represent only minimum values due to an incomplete eruption record. Unfortunately, limited data precluded the calculation of eruption frequencies for the Solomon Islands, Fiji and Samoa. A first-order analysis of the populations potentially impacted by large volcanic eruptions suggest that (1) volcanic disasters affecting populations of >100,000 can be expected at least every decade in Indonesia and once every few decades in the Philippines and (2) a volcanic disaster impacting >1% of the population can be expected twice a century in Vanuatu, twice a millennium for Indonesia and the Philippines, and around every millennium in Papua New Guinea and Tonga