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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]

The Manila subduction zone is located at the plate boundary where the Philippine Sea plate (PSP) moves northwestward toward the Eurasian plate (EU) with a high convergence rate. However, historically, no large earthquakes greater than Mw7 have been observed across the northern Manila subduction zone. The poorly understood plate interaction between these two plates in this region creates significant issues for evaluating the seismic hazard. Therefore, the variation of mantle lithospheric buoyancy is calculated to evaluate the plate coupling status across the northern Manila subduction zone, based on recently published forward gravity modeling constrained by the results of the P-wave seismic crustal structure of the TAIGER (Taiwan Integrated Geodynamic Research) project. The results indicate weak plate coupling between the PSP and EU, which could be related to the release of the overriding PSP from the descending EU’s dragging force, which was deduced from the higher elevation of the Luzon arc and the fore-arc basin northward toward the Taiwan orogen. Moreover, serpentinized peridotite is present above the plate boundary and is distributed more widely and thickly closer to offshore southern Taiwan orogen. We suggest that low plate coupling may facilitate the uplifting of serpentinized mantle material up to the plate boundary. [ABSTRACT FROM AUTHOR]