The Philippine Trench (also Philippine Deep, Mindanao Trench, and Mindanao Deep) is a

submarine trench Oceanic trenches are prominent long, narrow topographic depressions of the ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic tren ...

to the east of the Philippines. The trench is located in the Philippine sea of the western North Pacific Ocean and continues NNW-SSE. It has a length of approximately and a width of about from the center of the Philippine island of Luzon trending southeast to the northern Maluku island of

Halmahera Halmahera, formerly known as Jilolo, Gilolo, or Jailolo, is the largest island in the Maluku Islands. It is part of the North Maluku province of Indonesia, and Sofifi, the capital of the province, is located on the west coast of the island. Hal ...

in Indonesia. At its deepest point, the trench reaches 10,540 meters (34,580 ft or 5,760 fathoms). PhilippineMobileBelt007

Immediately to the north of the Philippine Trench is the East Luzon Trench. They are separated, with their continuity interrupted and displaced, by

Benham Plateau The Benham Rise, officially known as Philippine Rise, is an extinct volcanic ridge located in the Philippine Sea approximately east of the northern coastline of Dinapigue, Isabela. The rise has been known to the people of Catanduanes as Kalipu ...

on the Philippine Sea Plate.

Information

The Philippine trench is hypothesized to be younger than 8–9 million years old. The central part of the Philippine fault formed during the Plio-Pleistocene times is considered to be an active depression of the Earth's crust. The trench formed from a collision between the Palawan and Zamboanga plates. This caused a change in geological processes creating a

subduction zone Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

, that is dropping the ocean floor deeper. The rate of

subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

on these plates is estimated to be about 15 cm per year. A convergent zone borders an estimate of 45% of the Philippine Trench today. Although there are vast areas of subduction zones, some authors have considered this region to have low seismic activity, though the USGS has recorded many earthquakes with magnitude ≥ 7.2 in the region as shown by the map to the side. Most recently, in 2012 the Philippine Trench experienced an earthquake of M_w 7.6 (the

2012 Samar earthquake An earthquake off the coast of Samar occurred on August 31, 2012, at 20:47 local time (12:47 UTC) in the Philippines. The populated islands of Visayas were struck by an earthquake of magnitude 7.6. The earthquake occurred at a depth of 45 km ...

). It hit the trench with a hypocenter depth of 34.9 km. Areas adjacent to the subduction zones have experienced large seismic activity. In 1897, northern Samar experienced a M_s 7.3 earthquake while in 1924 southern Mindanao experienced one with a M_s 8.2.

Depth

The trench reaches one of the greatest depths in the ocean. Its deepest point is known as Galathea Depth and reaches 10,540 meters (34,580 ft or 5,760 fathoms).

Sedimentation

Sedimentation of the Philippine trench contains slightly metamorphosed,

calc-alkalic The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic mag ...

, basic,

ultrabasic rock Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed ...

and sand grains. The southern area of the trench contains homogeneous blue clay silt and is poor in lime. Sand grains that were also found contained fresh

basaltic andesite Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central Ameri ...

. The sediments found in the trenches are hypothesized to have been deposited by turbidity currents. A turbidity current is an underwater current that moves rapidly and carries sediment.

Significant quakes

This is a list of significant quakes related to the Philippine Trench, which are 7.0+

Trenches in the Philippine region

Known trenches in

LuzViMinda Luzviminda (sometimes LuzViMinda) is a ''portmanteau'' of Luzon, Visayas, and Mindanao, the names of the three major island groups of the Philippines. It is a feminine given name. Manila Trench 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 , in contrast with the average depth of the South China Sea of about . It is ...

East Luzon Trench The Philippine Trench (also Philippine Deep, Mindanao Trench, and Mindanao Deep) is a submarine trench to the east of the Philippines. The trench is located in the Philippine sea of the western North Pacific Ocean and continues NNW-SSE. It has a ...

Negros Trench The Negros Trench is an oceanic trench located northeast of the Sulu Trench and west of Negros Island Region in Visayas, the trench is located in the Sunda Plate in the southwestern region of the Pacific Ocean. The depth of the Negros Trench ...

Sulu Trench The Sulu Trench is an oceanic trench in the Pacific Ocean, located west of the islands of Mindanao and Sulu in the Philippines. The trench reaches a depth of about 5,600 metres (18,400 ft), in contrast with the average depth of the South Ch ...

Cotabato Trench The Cotabato Trench is an oceanic trench in the Pacific Ocean, off the southwestern coast of Mindanao in the Philippines. Along this trench the oceanic crust of the Sunda Plate beneath the Celebes Sea is being subducted beneath the Philippines ...

References

{{coord missing, Pacific Ocean Philippine Sea Oceanic trenches of the South China Sea Philippine tectonics Subduction zones Geology of Indonesia