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The Manila Trench is an oceanic trench in the Pacific Ocean, located west of the islands of Luzon and Mindoro in the Philippines. The trench reaches a depth of about 5,400 metres (17,700 ft), [ 8 ] in contrast with the average depth of the South China Sea of about 1,500 metres (4,900 ft).
The Manila Trench results from eastward subduction of the Eurasian plate (Sundaland Block) beneath the western side of the Philippine Mobile Belt. Subduction along the north-trending trench started in late Oligocene to early Miocene. [4] [23] [24] It has an average subduction rate at 1–2 cm (0.39–0.79 in) per year, slowing towards the north ...
The trough is a well-developed basin with active subduction into the Manila Trench system with complexities stemming from the offshore extension of the Philippine Fault System into the trough. Multi-channel seismic data suggests that the basin's sedimentary deposits resulted from multiple periods of emplacement and erosion .
Subduction of Late Oligocene to Early Miocene South China sea oceanic crust occurs at the Manila Trench. Subduction of Eocene Philippine Sea oceanic crust occurs at the East Luzon Trough – Philippine Trench system. The strike-slip, left lateral fault, Philippine fault system is associated with the northward movement of the belt. [14]
Obduction zones occurs when the continental plate is pushed under the oceanic plate, but this is unusual as the relative densities of the tectonic plates favours subduction of the oceanic plate. This causes the oceanic plate to buckle and usually results in a new mid-ocean ridge forming and turning the obduction into subduction.
All areas close to active subduction zones show increased hazard. [9] In Metro Manila the estimated hazard has a mean PGA of 0.32 g for a PoE of 10% in 50 years. The main hazard comes from shallow fault sources, such as the Marikina Valley Fault System, but there is an important contribution to the overall hazard from the Manila subduction zone ...
These two tectonic features thus correlate to a similar time of development. The formation of the PFZ was a result of two stages. The first stage began at ~10 Ma, when the northern segments of the PFZ developed due to the convergence of the China Sea Crust underneath the nearby Manila Trench. The lack of accretionary prism at the Philippine ...
The trench was active during the Oligocene. The Sierra Madre Basin and Isabella Ridge may represent the trench, forearc basin, and subduction complex. [5] [6] The rate of subduction on the Philippine Sea Plate is estimated to be around 2–3 cm per year. [7] A transfer zone borders an estimate of 55% of the East Luzon Trough today. [8]