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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
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)
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, running through the provinces of Rizal, the Metro Manila cities of Quezon, Marikina, Pasig, Taguig and Muntinlupa, and the provinces of Cavite and Laguna, before ending in Canlubang in the south.^[1]

Fault segments

The fault contains two major segments: the West Valley Fault (WVF) and the East Valley Fault (EVF).

West Valley Fault

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

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

East Valley Fault

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

Threat

Based on kinematic block models that utilize GPS, actual fault geometry, and earthquake focal mechanisms, the western segment of the Marikina Valley fault system was resolved to be almost fully locked, meaning it is currently accumulating and loading elastic strain at a rate of 10 to 12 mm/yr.^[4] The fault poses a threat of a large-scale earthquake with an estimated magnitude between 6–7 and as high as 7.6^[5] to Metro Manila and surrounding provinces, with a 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]

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

References

^ ^a ^b ^c ^d ^e ^f Malicdem, Ervin (August 16, 2017). "Barangays and Buildings Traversed by the Valley Fault System". Schadow1 Expeditions. Retrieved September 7, 2017. There are about 6,331 structures that are directly above the Valley Fault System within a 10-meter proximity which would be in potential danger of destruction once the slip-fault moves. This sums up to an area of 2,964.10 square kilometers in danger of collapse.
^ ^a ^b ^c Rimando, Rolly E.; Knuepfer, Peter L.K. (2004). "Neotectonics of the Marikina Valley fault system (MVFS) and tectonic framework of structures in northern and central Luzon, Philippines". Tectonophysics. 415 (1–4): 17–38. doi:10.1016/j.tecto.2005.11.009.
^ ^a ^b "'Big One' Is Possible But Metro Is Unprepared". Quezon City, Philippines: Bulatlat. August 14, 2004. Retrieved February 3, 2010. If a major earthquake were to hit Metro Manila today, the devastation would be so big even disaster response authorities cannot simply cope with it. And it even looks like disaster preparedness occupies a low priority among officials down to the municipal level.
^ Galgana, Gerald (2007). "Analysis of crustal deformation in Luzon, Philippines using geodetic observations and earthquake focal mechanisms". Tectonophysics. 432 (1–4): 63–87. Bibcode:2007Tectp.432...63G. doi:10.1016/j.tecto.2006.12.001.
^ Nelson, Alan R.; Personius, Stephen F.; Rimando, Rolly E.; Punongbayan, Raymundo S.; Tungol, Norman; Mirabueno, Hannah; Rasdas, Ariel (2000). "Multiple Large Earthquakes in the Past 1500 Years on a Fault in Metropolitan Manila, the Philippines". Bulletin of the Seismological Society of America. 90 (1): 84. Bibcode:2000BuSSA..90...73N. doi:10.1785/0119990002.
^ ^a ^b Ubac, Michael (June 20, 2009). "UN to Metro Manila: Ready for Big One?". Inquirer.net. Philippine Daily Inquirer. Retrieved January 30, 2010. Is Metro Manila prepared for the Big One?
^ ^a ^b "Big earthquake in Marikina Valley fault line?". Pinoymoneytalk.com. June 20, 2009. Retrieved January 30, 2010. The United Nations is advising the Philippines to be ready for an upcoming big earthquake. A quake with a magnitude of 7 or higher on the Richter scale is sure to hit Metro Manila, they say, but the bigger question is when exactly this will happen.
^ Malicdem, Ervin (August 25, 2017). "LIST: 99 Villages and Subdivisions Traversed by the Valley Fault System". Schadow1 Expeditions. Retrieved September 7, 2017.