Convergence
between rigid Sundaland (SU) and the Philippine Sea plate (PH) is
distributed across a 600 km-wide zone including in the Philippines
the Sundaland stretched continental margin in Palawan/Borneo and the
newly accreted exotic Island arc extending from Luzon to the Molucca
Sea. GPS results indicate PH/SU convergence is mainly absorbed along
main plate boundaries, but also within Sundaland where major
sedimentary basins were developed. Excluding motion along the
Philippine Fault, the balanced budgets of active shortening in the
PMB shows the Luzon Visayas and Mindanao islands belong to rather
rigid blocks.
A new
tomographic model built across the Philippine Mobile Belt was used
to image the subducted slabs in the mantle, providing a guideline
for the subduction history of the Philippines. When compared with
the timing of the island arc volcanism related to these subductions
in the Philippines, the tomographic images of the slabs help
constrain average the finite motion along the main PMB convergent
boundaries.
The
obtained velocities are then compared to the instantaneous rates of
deformation provided by the GPS results of the GEODYSSEA (EC/ASEAN)
project across the same plate boundaries. We discuss the fit that
exists between the active convergence rates across the main trenches
on both sides of the PMB, and the long term subduction velocities
obtained from geologic data and tomographic images.