Negros Trench

The Negros Trench 50-100 kilometers west of Visayas, The Sulu Trench in the southwest, Manila Trench west-northwest, and the Philippine Trench in the east

1922

1925

1948

1950

1951

1990

2011

2012

2014

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Epicenters of large earthquakes ≥ 6.4 M_w along the Negros Trench, from 1922 ^[1] 1925 ^[2] 1948 ^[3] 1950 ^[4] 1951 ^[5] 1990 ^[6] 2011 ^[7] 2012 ^[8] 2014 ^[9]

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 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, ^[10] which would later form the Negros Trench.

Background

The Negros trench was formed from subduction of the Eurasian Plate underneath the Philippine Sea plate which initiated during the Early Miocene (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 8–9 million years ago, This trench is located west of the Visayan Islands. 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. 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

Year	Location	Moment magnitude	Depth	Casualties
1922	west of Looc	6.5	15.0 km	-
1925	north of Nalundan	6.7	15.0 km	17
1948	north-northeast of Buga	7.8	15.0 km	74
1950	south-southeast of San Nicolas	6.5	25.0 km	-
1951	west-northwest of Linaon	6.5	25.0 km	1
1990	east-southeast of Union	7.1	18.1 km	8
2011	west-southwest of Cayhagan	6.4	19.0 km	-
2012	north-northeast of Jimalalud	6.7	11.0 km	51–113
2014	west-southwest of Alim	6.3	15.5 km	-

References

1. "M 6.5- Luzon, Philippines". United States Geological Survey.
2. "M 6.7 - Visayas, Philippines". United States Geological Survey.
3. "M 7.8 -Visayas, Philippines". United States Geological Survey.
4. "M 6.7 -Visayas, Philippines". United States Geological Survey.
5. "M 6.5 -Visayas, Philippines". United States Geological Survey.
6. "M 7.1 -Visayas, Philippines". United States Geological Survey.
7. "M 6.4-Visayas, Philippines". United States Geological Survey.
8. "M 6.7 -Visayas, Philippines". United States Geological Survey.
9. "M 6.3-Negros, Philippines". United States Geological Survey.
10. "Journal of Geophysical Research: Solid Earth". AGU Journals. Retrieved 2022-03-10.