Potential for future eruptive activity in Taiwan and vulnerability to volcanic hazards

Taiwan is subjected to several natural hazards such as extreme weather, seismic activity or tsunamis excited by earthquakes occurring along the Pacific Ocean subduction zones. Fortunately, Taiwan has not experienced any volcanic activity in historical times, a fact which reinforced the belief that its volcanic centers are by now extinct. During the past decade, volcanological, seismological and geochemical observations have shown that such a belief is erroneous and that two of Taiwan’s volcanic centers (Tatun Volcano Group and Kueishantao island) have potential for future eruptive activity. Additionally, there is historical evidence for four submarine eruptions offshore the northern and eastern coast of Taiwan over the last 150 years. The types of volcanic hazards that may affect Taiwan’s infrastructure and population are ashfall, pyroclastic flows, lava flows, landslides/volcanic debris avalanches, lahars, phreatic explosions and tsunami. Two of Taiwan’s nuclear power plants (and a third whose construction has been temporarily suspended) are close to the volcanic centers and could be affected by ashfall and lava flows, an issue that needs to be addressed by the operator of the plants. Even though the probability of future volcanic activity is low, it has to be recognized that the vulnerability to volcanic hazards for an advanced technological society such as Taiwan’s has increased considerably. Volcanic risk therefore cannot be considered insignificant, and its mitigation has to be addressed by a co-ordinated research/monitoring program. Furthermore, the development of contingency plans is a must for such high risk phenomena even if they are considered “low probability” events.