Surprisingly young age for the Tatun Volcano Group in northern Taiwan : a volcanic hazard assessment

Abstract

The Tatun Volcano Group (TVG) is located at Northern Taiwan. The TVG was generally believed to be an extinct volcano decades ago, until recent decades studies suggested that the TVG is active instead. However, the determined age of the young eruptions in the TVG in different studies still have a huge inconsistency. Besides, volcanic hazard assessment and related mitigation measures were still insufficient. As a result, this study reviewed the age of young eruptions in the TVG by 40Ar/39Ar ages, and provided a basic study of a volcanic hazard assessment and mitigation measures for potential eruptions in the TVG. The age dating work and sampling were provided by my advisor, Dr. Chang, Su- Chin. The yielded age of the samples is 86 ± 4 ka, which is much younger than other previous studies. This may be due to several factors, including differences in dating methods and sampling quality. A hazard assessment was done which focused on the impacts of several volcanic hazards (lava flows, pyroclastic flows, lahars, and airfall tephra) and their estimated impact areas. The assessment was literature review based, supported by mapping and modelling. To estimate the impact area of lava flows, pyroclastic flows and lahars, QGIS and Digital Elevation Model (DEM) were used for construction of topographic map. On the other hand, Gaussian plume model was adopted to estimate the potential impact area of volcanic ashes. It was found that the lava flows and pyroclastic flows have smaller impact areas, while lahars and airfall tephra (especially ashes) have much larger impact areas. Study on mitigation measures based on literature review was carried out referring to the hazard assessment. The suggested mitigation measures included planning, monitoring and forecasting, education, and engineering measures.