Cotabato Trench

Short description: Oceanic trench in the Pacific Ocean

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For recent Philippine earthquakes, a third of the largest ones (M ≥ 6.3) since 2001 have been near the 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 Mobile Belt. It forms part of a linked set of trenches along the western side of the Philippines formed over east-dipping subduction zones, including the Manila Trench and the Negros Trench.[1] At its northern end the rate of convergence across this boundary is about 100 mm per year.[2] It is a relatively young structure, forming during the late Miocene to Pliocene.[3] This age is consistent with the estimated age of the sedimentary rocks in the accretionary wedge associated with the trench and the age of adakitic arc rocks on Mindanao thought to date the onset of subduction.[4]

## Seismicity

Main tectonic structures around the Philippines

The trench is associated with large megathrust earthquakes, including the 1918 Celebes Sea earthquake (M 8.3), the 1976 Moro Gulf earthquake (M 8.0) and the 2002 Mindanao earthquake (M 7.5).[5][2]

## Tsunami hazard

The Cotabato Trench is one of the main structure around the Philippines likely to be associated with tsunamigenic earthquakes. The tsunami generated by the 1976 earthquake caused about 4,000 deaths on Mindanao. Modelling of likely further tsunamis along the Cotabato Trench suggests that run-ups of several metres are likely for future earthquakes similar in size to the 1976 event.[6]

In January 2026, an earthquake swarm along the trench with magnitudes ranging from 1.4 to 5.2 forced the closure of schools and government offices in Sultan Kudarat.[7]

## References

1. ↑ Wu, W.N.; Lo, C.-L.; Lin, J.-Y. (2017). "Spatial variations of the crustal stress field in the Philippine region from inversion of earthquake focal mechanisms and their tectonic implications". Journal of Asian Earth Sciences 142: 109–118. doi:10.1016/j.jseaes.2017.01.036. Bibcode: 2017JAESc.142..109W.
2. ↑ 2.0 2.1 Template:Cite anss
3. ↑ Jego, S.; Maury, R.C.; Polve, M.; Yumul, G.P. Jr.; Bellon, H.; Tamayo, R.A. Jr.; Cotton, J. (2005). "Geochemistry of Adakites from the Philippines: Constraints on Their Origins". Resource Geology 55 (3): 161–185. doi:10.1111/j.1751-3928.2005.tb00239.x. Bibcode: 2005ReGeo..55..163J. https://www.researchgate.net/publication/227972856.
4. ↑ Schlüter, H.U.; Block, M.; Hinz, K.; Neben, S.; Seidel, D.; Djajdihardja, Y. (2001). "Neogene sediment thickness and Miocene basin-floor fan systems of the Celebes Sea". Marine and Petroleum Geology 18 (7): 849–861. doi:10.1016/S0264-8172(01)00027-7.
5. ↑ Stewart, G.S.; Cohn, S.N. (1979). "The 1976 August 16, Mindanao, Philippine earthquake (Ms = 7.8) - evidence for a subduction zone south of Mindanao". Geophysical Journal of the Royal Astronomical Society 57 (1): 51–65. doi:10.1111/j.1365-246X.1979.tb03771.x. Bibcode: 1979GeoJ...57...51S.
6. ↑ Løvholt, F.; Kühn, D.; Bungum, H.; Harbitz, C.B.; Glimsdal, S. (2012). "Historical tsunamis and present tsunami hazard in eastern Indonesia and the southern Philippines". Journal of Geophysical Research 117 (B9): B09310. doi:10.1029/2012JB009425. Bibcode: 2012JGRB..117.9310L. https://hal.archives-ouvertes.fr/hal-00724854/file/2012JB009425.pdf.
7. ↑ "Earthquake swarm in Sultan Kudarat linked to movements along Cotabato Trench". GMA News. 22 January 2026. https://www.gmanetwork.com/news/scitech/science/973809/earthquake-swarm-sultan-kudarat-cotabato-trench/story/.

* v
* t
* e

Tectonic plates of Southeast Asia–New Guinea (Australian Plate-Pacific Plate Convergence Zone)

Large|

* Caroline Plate
* Philippine Sea Plate
* Sunda Plate

Small|

| West|

* Burma Plate

|

Philippines|

* Philippine Mobile Belt

Indonesia|

* Banda Sea Plate
* Bird's Head Plate
* Halmahera Plate
* Molucca Sea Collision Zone
* Molucca Sea Plate
* Sangihe Plate
* Timor Plate

New Guinea|

* Maoke Plate
* North Bismarck Plate
* Manus Plate
* Solomon Sea Plate
* South Bismarck Plate
* Woodlark Plate

Faults|

* Flores Back Arc Thrust Fault
* Great Sumatran Fault
* Marikina Valley Fault System
* New Britain Subduction Zone
* Palu-Koro Fault
* Philippine Fault System
* Ramu-Markham Fault
* Sorong Fault

Trenches
and troughs|

* Java Trench (Sunda) with Mentawai Trough
* Sunda Trough
* Timor Trough

Philippines|

* Cotabato Trench
* Manila Trench
* North Luzon Trough
* Negros Trench
* Palawan Trench
* Philippine Trench
* East Luzon Trench
* Sulu Trench

Sulawesi & Moluccas|

* Aru Trough
* Banda Trench
* Ceram Trough
* Salajar Trough
* Sangihe Trough
* Talaud Trough
* Ternate Trough

Timor|

* Aur Trough
* Tanimbar Trough

New Guinea|

* Ayu Trough
* Kilinailai Trench
* Manokwari Trough
* Lyra Trough
* Manus Trench
* Mussau Trench
* New Guinea Trench
* Pocklington Trough
* New Britain Trench (Bougainville)
* West Caroline Trough
* West Melanesian Trench

Subsea plateaus
and basins|

* Arafura Basin
* Aru-Tanimbar Basin
* Bengkulu Basin
* Benham Plateau
* Bula Basin
* East Natuna Basin
* Geelvinck (Cendrawasih) Basin
* Minahasa Basin
* North Australian Basin
* North Biak Basin
* North Flores Basin
* Northern East Java Basin
* Northern Makassar Basin
* Sawu Basin
* Southern Makassar Basin
* Talaud Basin
* Weber Basin
* West Halmahera Basin
* West Natuna Basin

[ ⚑ ]  6°00′N 123°36′E﻿ / ﻿6.0°N 123.6°E﻿ / 6.0; 123.6

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