Volcanic Hazard Zone Expansion at Kanlaon Volcano: A Scenario-Based Multi-Factor Analysis

Abstract

The Kanlaon Volcano is among the most active volcanic structures found in the Philippines. However, it is also a potential threat to neighboring area. This case study will determine the potential expansion of the volcanic danger zone of Kanlaon Volcano. A danger zone expansion index (∆DZ), which can determine the expansion of the danger zone of volcanoes, is created through various factors. Among these factors are eruption intensity, pyroclastic activity, rainfall and/or lahar potential, wind influence, topography, and gas emission. There are three volcanic activity levels; low, moderate, and high. These levels are given a standard rating of 0-3, which correspond to PHIVOLCS and PAGASA data as well as various scientific documents. Results indicate a clear positive relationship between volcanic activity intensity and hazard zone expansion. In the case of low volcanic activity, the ∆DZ value was 1.17, which is an indication that there is limited expansion beyond the hazard zone boundaries. In the moderate activity case, the ∆DZ value was 2.00, which is an indication of moderate to high expansion, while the high activity case reached a ∆DZ of 3.00, which is the worst-case expansion of the hazard zones. The observations clearly illustrate that hazard zones for volcanic dangers are not constant and need to be varied based on prevailing volcanic activities and conditions of the environment. Modelling through multiple factors and scenarios is an effective means of pre-disaster preparedness and planning for hazard zoning in volcanic areas.