Evidence of a subducted slab beneath central Taiwan
Speaker: Yen-Fu Chen
Abstract
The Manila subduction system is located on the south of Taiwan. The features of the subduction system disappear near Taiwan so it is debated whether or not a subducted slab exists beneath central Taiwan. In seismic profiles, no earthquakes occur beyond 80 km depth implicating that the Manila subduction system doesn't extend to central Taiwan. However, the tomographic images show a high-velocity zone beneath central Taiwan although the resolution of the tomographic inversion is poor on top layer and worse at depth. To find more evidence of the subducted slab existing, the seismic effects are investigated by using local broadband stations. If seismic wave propagates along a high-velocity slab to station, then the first arrival would have a reduced amplitude and an earlier arrival time. It is consistent with the rays from Tonga- Kermadec subduction zone to central Taiwan stations. The phenomena of reduced amplitudes in Tonga-Kermadec events are not reproduced in Hindu Kush events. It suggests that there is an eastern dipping slab beneath central Taiwan.
Reference
Lallemand, S., Font, Y., Bijwaard, H., Kao, H., 2001. New insights on 3-D plates interaction near Taiwan from tomography and tectonic implications. Tectonophysics 335, 229-253.
Chen, P.-F., Huang, B.-S., Liang, W.-T., 2004. Evidence of a slab of subducted lithosphere beneath central Taiwan from seismic waveforms and travel times. Earth and Planetary Science Letters 229, 61-71.