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The Tatun Volcanic Group (TVG) in northern Taiwan is the sole volcanic region on the island, with its last eruptive episode around 5,500 years ago. It has been suggested that the TVG retains the capacity for volcanic explosivity which has the potential to devastate the nearby Taipei metropolitan area of 7 million inhabitants. Though the probability of future eruption is low by probabilistic estimation, the vulnerability to volcanic hazards is high for Taipei given that it is the centre of population, industry, and government for the island. An assessment of any activity precursors is thus vital but also particularly challenging. Here, we perform an eruption-potential assessment based on the analysis of a sixteen-year Land Surface Temperature (LST) time series of data derived from satellite-retrieved thermal imagery. A Hilbert-Huang Transform (HHT) is applied to decompose oscillatory components of various timescales within the LST time series. The annual-period components are compared with those from two active volcanoes in the Philippines to assess the potential of eruption cycles in the TVG. Results from the Philippine volcanoes show that annual-period components of LST tend to lose their regularity following an eruption. By contrast, the regular annual period component of LST of the TVG Taiwan suggests a quiet and resting status with no sign of an imminent eruption. [ABSTRACT FROM AUTHOR]

Proposed in the late 1980s, cumulative absolute velocity (CAV) is a new intensity measure for earthquake ground motion characterizations, followed by studies and applications such as CAV ground motion prediction equations (GMPEs). In this study, two new CAV GMPEs were developed with 24,667 strong-motion records from Taiwan, and the first CAV seismic hazard assessment for Taipei (the most important city in Taiwan) was then conducted using the local CAV models. It shows that the annual rate for the study area to encounter a ground motion with CAV >0.97 g-sec is 0.002 per year, corresponding to a 10% occurrence probability in 50 years. By contrast, the deterministic scenario-based analysis shows that the CAV seismic hazard is about 0.60 g-sec for the study area. Future studies are worth conducting to develop more sophisticated, local CAV GPMEs and to explore more applications of such CAV prediction models, such as the developments of PGA-CAV joint probability distributions for conducting PGA-CAV joint seismic hazard assessments. • First CAV GMPE for Taiwan areas. • More than 4,000 strong motion records used. • CAV-based seismic hazard analysis for Taipei. [ABSTRACT FROM AUTHOR]