Abstract
The Tatun Volcano Group (TVG), located at the northern tip of Taiwan, is situated near the Taipei metropolitan area. A future eruption of the TVG could have a significant impact not only on Taipei but also on the global economy, as Taiwan produces over 90% of the world's most advanced semiconductor chips. Although a magma reservoir has been identified beneath the TVG, it remains uncertain whether it contains eruptible magma. Using seismic data recorded by the Formosa Array, we detected strong seismic reflections from the magma reservoir. Both travel-time modeling and polarization of these reflections indicate that the top of the reservoir lies at a depth of approximately 13-15 km-significantly deeper than the ~ 8 km depth previously estimated from seismic tomography. This notable discrepancy supports a conceptual model in which magma reservoirs are divided into eruptible and non-eruptible portions. Our findings suggest that a substantial amount of eruptible magma may exist beneath the TVG. However, a volcanic eruption would only occur if the pressure from accumulating magma exceeds the rock load of the overlying crust.