Seismicity and volcanism in the southwestern Okinawa trough (northeast Taiwan)

Most of the volcanic activities observed in the Okinawa backarc basin are linked to the subduction of the Philippine Sea plate (dehydration, upwelling of asthenosphere). We have analyzed data acquired from a passive OBS experiment and available geophysical data (magnetic anomalies, seismic profiles and onland recorded earthquakes) to determine the depth of magnetic sources, earthquake locations, crustal and lithospheric 3D velocity models, spectral analyses of P-wave and seismic tomography. The calculations of the top and bottom of magnetic sources were performed in the East China Sea and in the southern Okinawa trough. This analysis shows the presence of a thin crust along 123.3°E longitude and a thick crust beneath the Cross Backarc Volcanic Trail (CBVT) volcanic area.