Philippine Fault System
Encyclopedia
The Philippine Fault System is an inter-related system of faults throughout the whole of the Philippine Archipelago, primarily caused by tectonic forces compressing the Philippines
into what tectonic geophysicists call the Philippine Mobile Belt
.
The Philippine Mobile Belt is composed of a large number of accretionary blocks and strips. Most strips are long and narrow like the Zambales ophiolites which is at least 400 km long and 50 km wide. The strips generally run north-south and the zones of convergence are usually demarkated by fault lines. The Philippine Mobile Belt is compressed on the west by the Eurasian Plate
and two arms of the Sunda Plate
, and on the east by the Philippine Sea Plate. These tectonic plates
have compressed and lifted parts of the Philippines causing extensive faulting, primarily on a north-south axis. The main fault runs most of the length of the Philippines and is called the Philippine Fault (see Gallery). In northern Luzon, the fault has become braided and is no longer single. All faults in the Philippines are inter-related by the tectonic forces causative of the Philippine Mobile Belt, or its tectonic induced volcanism
. A more complete understanding can be gained by viewing the faults in the Philippines as an inter-related Philippine Fault System.
The Philippine fault, probably active since the Middle Miocene
is a recent example of the north-south strike-slip fault zones of Luzon. The N150E segment, which breaks the meridian continuity of the Philippine Fault system in Luzon, is located to the west of Benham Plateau
on the western edge of the Philippine Sea Plate. The N150E fault probably has a recent genesis and could be a mechanism to absorb backwards the convergence between Benham Plateau and the east Luzon arc.
Following the major 1990 Luzon earthquake
, scientists reconsidered their fault models and following the lead of Pinet and Stephan (1989), thought it likely that Benham Plateau is still displacing central Luzon and the Philippine Fault System to the west, and so caused the 1990 Luzon earthquake. The 20 second or 50 second wave in the 1990 quake developed a new east-west sub-fault, which terminated disastrously at Baguio.
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
into what tectonic geophysicists call the Philippine Mobile Belt
Philippine Mobile Belt
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 zones, the Manila Trench to the west and the Philippine Trench to the east, as well as the...
.
The Philippine Mobile Belt is composed of a large number of accretionary blocks and strips. Most strips are long and narrow like the Zambales ophiolites which is at least 400 km long and 50 km wide. The strips generally run north-south and the zones of convergence are usually demarkated by fault lines. The Philippine Mobile Belt is compressed on the west by the Eurasian Plate
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...
and two arms of the Sunda Plate
Sunda Plate
The Sunda Plate is the tectonic plate on which the majority of Southeast Asia is located. It was formerly considered a part of the Eurasian Plate, but GPS measurements have confirmed its independent movement at 10 mm/yr eastward relative to Eurasia...
, and on the east by the Philippine Sea Plate. These tectonic plates
Tectonic Plates
Tectonic Plates is a 1992 independent Canadian film directed by Peter Mettler. Mettler also wrote the screenplay based on the play by Robert Lepage. The film stars Marie Gignac, Céline Bonnier and Robert Lepage.-Plot summary:...
have compressed and lifted parts of the Philippines causing extensive faulting, primarily on a north-south axis. The main fault runs most of the length of the Philippines and is called the Philippine Fault (see Gallery). In northern Luzon, the fault has become braided and is no longer single. All faults in the Philippines are inter-related by the tectonic forces causative of the Philippine Mobile Belt, or its tectonic induced volcanism
Volcanism
Volcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....
. A more complete understanding can be gained by viewing the faults in the Philippines as an inter-related Philippine Fault System.
The Philippine fault, probably active since the Middle Miocene
Middle Miocene
The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene....
is a recent example of the north-south strike-slip fault zones of Luzon. The N150E segment, which breaks the meridian continuity of the Philippine Fault system in Luzon, is located to the west of Benham Plateau
Benham Plateau
Benham Plateau , also known as the Benham Rise, is a seismically active undersea region and extinct volcanic ridge east of the Philippines, in the Philippine Sea. Under the Philippine Sea lies a number of Basins including the West Philippine Basin of which inside the Basin is located the Central...
on the western edge of the Philippine Sea Plate. The N150E fault probably has a recent genesis and could be a mechanism to absorb backwards the convergence between Benham Plateau and the east Luzon arc.
Following the major 1990 Luzon earthquake
1990 Luzon earthquake
The Luzon earthquake occurred on Monday, July 16, 1990, at 4:26 PM local time in the Philippines. The densely populated island of Luzon was struck by an earthquake with a 7.8 Ms...
, scientists reconsidered their fault models and following the lead of Pinet and Stephan (1989), thought it likely that Benham Plateau is still displacing central Luzon and the Philippine Fault System to the west, and so caused the 1990 Luzon earthquake. The 20 second or 50 second wave in the 1990 quake developed a new east-west sub-fault, which terminated disastrously at Baguio.