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CURRENT TECTONIC FEATURES OF THE
PHILIPPINES FROM GEOMORPHIC, GEOPHYSICAL, GEOLOGIC AND GPS DATA
Ramos, E. G.*, Morado, A. A. Jr.**,
Aurelio, M. A.*** and Ferrer, A. P.**
*Philippne Institute of Volcanology &
Seismology
Quezon City, Metro Manila, Philippines
**COMEXCO, Incorporated
Pasig City, Metro Manila,
***Mines and Geosciences Bureau
Quezon City, Metro Manila, Philippines
ABSTRACT
Details in the tectonic features
of the Philippines can be seen in the recent geomorphic, geophysical
and geologic and GPS data, hinting on the geometry of boundaries,
nature of deformation processes and direction of ongoing movement of
crustal segments that make up the archipelago. Integration of the
data with geologic, structural and seismicity data suggests
discontinuities in the major subduction zones, existence of possible
recently abandoned arcs and imbricate relationship between some
crustal blocks. These interpretations coincide with much of earlier
notions about the plate tectonics of the Philippines, and with the
concept that the archipelago is an amalgamation of arcs, oceanic and
continental blocks whose boundaries had been actively shifting. The
present observable features can be attributed to the inhomogeneity
of the crust that composes the region, causing shifts in position of
the margins and convergence of some blocks, and to changes in the
direction of movement of the surrounding tectonic plates (or in the
orientation of stress). All these features indicate that the
Philippine archipelago is mainly a complicated tectonic margin
absorbing the deformation between the Philippine Sea and the
Eurasian tectonic plates.
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