The Sulu Trench is an

oceanic trench Oceanic trenches are prominent, long, narrow topography, topographic depression (geology), depressions of the seabed, ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers ...

in the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

, located west of the islands of

Mindanao Mindanao ( ) is the List of islands of the Philippines, second-largest island in the Philippines, after Luzon, and List of islands by population, seventh-most populous island in the world. Located in the southern region of the archipelago, the ...

and

Sulu Sulu (), officially the Province of Sulu (Tausug language, Tausūg: ''Wilaya' sin Lupa' Sūg''; ), is a Provinces of the Philippines, province of the Philippines in the Sulu Archipelago. It was part of the Bangsamoro, Bangsamoro Autonomous R ...

in the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

. The trench reaches a depth of about 5,600 metres (18,400 ft), in contrast with the average depth of the

South China Sea The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by South China, in the west by the Indochinese Peninsula, in the east by the islands of Taiwan island, Taiwan and northwestern Philippines (mainly Luz ...

of about 1,500 metres (4,900 ft). The trench formed when the Sunda Plate (part of the Eurasian Plate) subducted below the

Philippine Mobile Belt In the geology of the Philippines, the Philippine Mobile Belt is a complex portion of the tectonic boundary between the Eurasian plate and the Philippine Sea plate, comprising most of the country of the Philippines. It includes two subduction ...

. The

convergent boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

terminates at the Negros Trench in the east. The Sulu Trench is not associated with frequent

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

s, but hosts volcanoes south of the trench, such as Mount Malindang.

Background

The Sulu Trench was formed from subduction of the Eurasian Plate underneath the

Philippine sea plate The Philippine Sea plate or the Philippine plate is a tectonic plate comprising oceanic lithosphere that lies beneath the Philippine Sea, to the east of the Philippines. Most segments of the Philippines, including northern Luzon, are part of ...

, which initiated during the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

(23.03-20.44 Million years ago). Historically, the trench was the site of a collision zone with the Palawan plate, which formed the

Philippine Trench The Philippine Trench (also called the Philippine Deep, Mindanao Trench, and the Mindanao Deep) is a Oceanic trench, submarine trench to the east of the Philippines. The trench is located in the Philippine sea of the western North Pacific Ocean ...

8–9 million years ago. The trench is located southwest of the

Visayas The Visayas ( ), or the Visayan Islands (Bisayan languages, Visayan: ''Kabisay-an'', ; Filipino language, Filipino: ''Kabisayaan'' ), are one of the three Island groups of the Philippines, principal geographical divisions of the Philippines, a ...

and north of the

Sulu Archipelago The Sulu Archipelago ( Tausug: Kapū'-pūan sin Sūg Sulat Sūg: , ) is a chain of islands in the Pacific Ocean, in the southwestern Philippines. The archipelago forms the northern limit of the Celebes Sea and southern limit of the Sulu Se ...

. It extends northeasterly in the

Sulu Sea The Sulu Sea (; Tausug: ''Dagat sin Sūg''; ; ) is a body of water in the southwestern area of the Philippines, separated from the South China Sea in the northwest by Palawan and from the Celebes Sea in the southeast by the Sulu Archipela ...

, from to . The rate of

subduction Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second p ...

in the Sulu Trench is approximately per year. Although there are vast areas of subduction zones, some authors have considered this region to have low

seismic activity An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

. There have been several earthquakes with a magnitude ≥6.4 in the region, with one of the recent ones in 1978, hitting the trench with a hypocenter depth of . Areas adjacent to the subduction zones have experienced large seismic activity. In 1942, Zamboanga Peninsula experienced a M7.2.

Seismicity

This is a list of significant earthquakes related to the Sulu Trench which have a magnitude of 6.4 or bigger.

References

Oceanic trenches of the Philippine Sea Philippine tectonics Subduction zones {{marine-geo-stub