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Marikina Valley Fault System

Marikina Valley Fault System
Lower and upper fault plain along the West Valley Fault in Carmona, Cavite
Map of the Marikina Valley Fault System showing relative motion and deformation
Etymology	Marikina
Named by	Philippine Institute of Volcanology and Seismology
Year defined	2010
Coordinates	14°38′N 121°5′E / 14.633°N 121.083°E / 14.633; 121.083
Country	Philippines
Region	Central Luzon, Metro Manila, Calabarzon
Cities	West: Marikina, Quezon City, Pasig, Taguig, Muntinlupa, General Mariano Alvarez, Carmona, Silang, San Pedro, Biñan, Santa Rosa, Cabuyao, Calamba East: Rodriguez, San Mateo
Characteristics
Segments	West Valley Fault, East Valley Fault
Length	146 km (91 mi)[1]
Displacement	10–12 mm (0.39–0.47 in)/yr
Tectonics
Plate	Philippine Sea Plate and Sunda Plate
Status	Active
Earthquakes	1658[citation needed], 1771[citation needed]
Type	Strike-slip fault
Movement	Dextral
Age	Gelasian
Orogeny	Luzon-Mindoro-Palawan Orogeny
Volcanic arc/belt	Macolod Corridor

The Marikina Valley Fault System, also known as the Valley Fault System (VFS), is a dominantly right-lateral strike-slip fault system in Luzon, Philippines.^[2] It extends from Doña Remedios Trinidad, Bulacan in the north and runs through the provincesofRizal, and the Metro Manila citiesofQuezon, Marikina, Pasig, Taguig and Muntinlupa, and the provinces of Cavite and Laguna that ends in Canlubang.^[1]

The fault contains two major segments, known as West Valley Fault (WVF) and East Valley Fault (EVF).

West Valley Fault

The west segment, known as the West Valley Fault (WVF), is one of the two major fault segments of the Valley Fault System which runs through Metro Manila to the cities of Marikina, Quezon City, Pasig, Taguig and Muntinlupa^[1] and moves in a dominantly dextral strike-slip motion.^[2] The West Valley Fault segment traverses from Doña Remedios TrinidadtoCalamba with a length of 129.47 kilometers (80.45 mi).^[1]

The West Fault is capable of producing large scale earthquakes on its active phases with a magnitude of 7 or higher.^[3]

East Valley Fault

The eastern segment, known as East Valley Fault (EVF), moves in an oblique dextral motion.^[2] It extends to about 17.24 kilometers (10.71 mi) from RodrigueztoSan Mateo in the province of Rizal.^[1]

Based on kinematic block models that utilize GPS, actual fault geometry, and earthquake focal mechanisms, the West segment of the Marikina Fault was resolved to be almost fully locked, meaning it is currently accumulating and loading elastic strain, at the rate of 10 to 12 mm/yr.^[4] The fault possesses a threat of a large scale earthquake with an estimated magnitude between 6–7 and as high as 7.6 ^[5]toMetro Manila and surrounding provinces with death toll predicted to be as high as 35,000^[6][7] and some 120,000 or higher^[6] injured^[7] and more than three million needed to be evacuated.^[3]

99 private villages and subdivisions inside 80 barangays are traversed directly by the fault^[8] and endangers 6,331 buildings in a span of 2,964.10 square kilometers (1,144.45 sq mi), to where majority are houses with 19 schools included in the list.^[1]

• Valley Fault System (VFS): Marikina Quadrangle – Philippine Institute of Volcanology and Seismology
• High resolution West Valley Fault maps launched - Rappler
• PHIVOLCS FaultFinder - This web app is a product of the joint collaboration between PHIVOLCS, DOST, GSJ, AIST. It was developed by Dr. Joel C. Bandibas of GSJ with the cooperation of the research and development personnel of PHIVOLCS.
• Media related to Marikina Valley Fault System at Wikimedia Commons