The Negros Trench is an

oceanic 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 ...

located northeast of the Sulu Trench and west of

Negros Island Region The Negros Island Region ( hil, Rehiyon sang Pulo sang Negros; ceb, Rehiyon sa Pulo sa Negros), also abbreviated and officially designated as NIR (unofficially ''Region XVIII''), was a short-lived administrative region in the Philippines which ...

Visayas The Visayas ( ), or the Visayan Islands (Visayan: ''Kabisay-an'', ; tl, Kabisayaan ), are one of the three principal geographical divisions of the Philippines, along with Luzon and Mindanao. Located in the central part of the archipelago, ...

, the trench is located in the Sunda Plate in the southwestern region of the

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

. The depth of the Negros Trench is unknown, in contrast it's neighboring trench the Sulu Trench has a depth of 5,600. During the Early-Miocine, the Sunda 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 z ...

, which would later form the Negros Trench.

Background

The Negros trench was formed from subduction of the

Eurasian Plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

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 o ...

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), The trench was previously the site of a collision zone with the Palawan plate, which formed the

Philippine 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 ...

8–9 million years ago, This trench is located west of the

Visayan Islands The Visayas ( ), or the Visayan Islands (Visayan: ''Kabisay-an'', ; tl, Kabisayaan ), are one of the three principal geographical divisions of the Philippines, along with Luzon and Mindanao. Located in the central part of the archipelago, it ...

. This trench moves 2–3 cm/year. Although there are vast areas of subduction zones, some authors have considered this region to have low

seismic activity An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, fr ...

. There has been a decent amount of earthquakes with a magnitude ≥6.4 in the region, with the most recent occurring in 2011. It hit the trench in a depth of 19.0 km. Areas adjacent to the subduction zones have experienced large seismic activity.

Seismicity

References

{{coord missing Geology of the Philippines Philippine tectonics Subduction zones Natural history of the Philippines Oceanic trenches of the South China Sea