Manila Trench

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The Manila Trench is an ocean trench in the South China Sea, west of the Philippines. It reaches a depth of about 5,000 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 slipping underneath the Philippine Plate.

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 Sundaland Block (part of Eurasia) subducts under the Luzon, producing this almost N-S trending trench. The Trench is terminated on the north by the Taiwan Collision, and by the Mindoro terrane(Sulu-Palawan block colliding with SW Luzon). It is an area pervaded by negative gravity anomalies (Hayes and Lewis, 1984);

Convergence between Luzon and the Manila Trench have been estimated using GPS measurements, and this value ranges from ~ 50+ mm/r in Taiwan, to 100 mm/yr near N. Luzon, and ~ 50 mm/yr near Zambales and ~20+mm/yr near Mindoro islands (Rangin et al., 1999; Galgana et al., 2007). 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 Sea Plate--Eurasian convergence (Kreemer et al., 2001; Galgana et al., 2007).