Study maps newly discovered fault zones off western Luzon
At A Glance
- Researchers from the University of the Philippines and National Central University in Taiwan identified four fault zones that appear to branch from the main Philippine Fault Zone, a major system associated with earthquakes and crustal movement across the country.
A team of researchers from Taiwan and the Philippines has discovered four previously unknown fault zones beneath the sea off western Luzon that appear to branch from the Philippine Fault Zone.
The findings were published in the Journal of Asian Earth Sciences and shared by the University of the Philippines Office of the Vice President for Academic Affairs (OVPAA) through its website and social media pages on July 3.
The researchers used advanced imaging tools, including high-resolution seafloor maps and seismic profiles, to examine underwater geological structures off western Luzon.
Their analysis identified four fault zones that appear to branch from the main Philippine Fault Zone, a major system associated with earthquakes and crustal movement across the country.
“One of these branches seems to extend the main fault to the Manila Trench—a major undersea feature where earthquakes and tsunamis can also originate,” the researchers said.
Seismic data also showed that the Manila Trench bends by about 35 degrees as it extends southward, aligning with the direction of the Philippine Fault Zone in central Luzon.
Below this region, the study found that the Earth’s crust appears to be torn at depth, with the northern portion of the subducting slab dipping more gently and the southern portion dipping more steeply.
The researchers said this deformation may be linked to two simultaneous tectonic processes: the southeastward collision of the Palawan Microcontinental Block and the northwestward docking of Benham Rise.
“By identifying these geologic structures, we can better understand the complex forces shaping Luzon and, more importantly, improve hazard assessments and earthquake preparedness for communities living near these potentially hazardous fault zones,” they said.
The study, titled “Segmentation of the Manila subduction zone and slab tearing beneath the Philippine mobile belt,” was authored by Shu-Kun Hsu, Wen-Nan Wu, Lien-Kai Lin, Shiou-Ya Wang, Yi-Ching Yeh, Kuan-Ting Chen, Yun-Jie Tsai, and Ching-Hui Tsai of the National Central University in Taiwan; and Leo T. Armada and Carla B. Dimalanta of the University of the Philippines.