Manila Trench

The Manila Trench is an ocean trench in the South China Sea, west of the Philippines. It reaches a depth of about 5,400 m, in contrast with the average depth of the South China Sea of about 1,500 m. It is created by subduction, in which the Eurasian Plate is subducting under the Philippine Mobile Belt.

The Manila Trench is associated with frequent earthquakes, and the plate movements which give rise to it are also responsible for the arc of volcanoes on the west side of the Philippine island of Luzon, including Mount Pinatubo.

The Sunda Plate (part of Eurasia) subducts under the Luzon Volcanic Arc, producing this almost N-S trending trench. The trench is terminated in the north by the Taiwan collision zone, and in the south by the Mindoro terrane (Sulu-Palawan block colliding with SW Luzon). It is an area pervaded by negative gravity anomalies.

Convergence between the Philippine Mobile Belt and the Manila Trench have been estimated using GPS measurements, and this value ranges from ~ 50+ mm/yr in Taiwan, to 100 mm/yr near N. Luzon, and ~ 50 mm/yr near Zambales and ~20+mm/yr near Mindoro island... Plate locking between the Sundaland Plate and Luzon is about 1% coupled, almost unlocked as determined by elastic block models, suggesting that the trench absorbs the Philippine Mobile Belt--Eurasian Plate convergence.

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