Complex mantle flows caused by multiple subducting slabs: P-wave tilting-axis anisotropic tomography of the Molucca Sea subduction zone

The Molucca Sea subduction zone is famous for its active divergent double subducted slab and located on the north side of the ongoing Java and Banda subduction zones. The spatial closeness of the subduction zones would causes a complex mantle flow field. To clarify the mantle dynamics, in this study, we present a P-wave tilting-axis anisotropic tomography by inverting a large number of local and teleseismic travel-time data recorded at 254 seismic stations in eastern Southeast Asia. Our anisotropic tomographic result shows that the mantle structure of the western Molucca Sea subduction zone is probably affected by the remote controls of the Java and Banda subduction zones. The mantle convection in the big mantle wedge west of the Molucca Sea subduction zone is possibly influenced by the east-west mantle flow associated with the compression of the Indo-Australian slab, as well as the north-south mantle flow related to the rollback of the Indo-Australian slab. In contract,  the eastern Molucca Sea subduction zone is virtually unaffected by other subduction zones, probably due to the domination of its still ongoing subduction.