The Marikina Valley fault system, also known as the Valley fault system (VFS), is a dominantly right-lateral

strike-slip fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

system in

Luzon Luzon ( , ) is the largest and most populous List of islands in the Philippines, island in the Philippines. Located in the northern portion of the List of islands of the Philippines, Philippine archipelago, it is the economic and political ce ...

, Philippines. It extends from Doña Remedios Trinidad,

Bulacan Bulacan, officially the Province of Bulacan (; ; ; ), is a Provinces of the Philippines, province in the Philippines located in the Central Luzon Regions of the Philippines, region. Its capital is the city of Malolos. Bulacan was established on ...

in the north, running through the

provinces A province is an administrative division within a country or state. The term derives from the ancient Roman , which was the major territorial and administrative unit of the Roman Empire's territorial possessions outside Italy. The term ''provi ...

of Rizal, the

Metro Manila Metropolitan Manila ( ), commonly shortened to Metro Manila and formally the National Capital Region (NCR; ), is the capital region and largest List of metropolitan areas in the Philippines, metropolitan area of the Philippines. Located ...

cities A city is a human settlement of a substantial size. The term "city" has different meanings around the world and in some places the settlement can be very small. Even where the term is limited to larger settlements, there is no universally agree ...

Quezon Quezon, officially the Province of Quezon () and historically known as Tayabas, is a Provinces of the Philippines, province in the Philippines located in the Calabarzon Regions of the Philippines, region on Luzon. Lucena, a highly urbanized ci ...

Marikina Marikina (), officially the City of Marikina (), is a Cities of the Philippines#Legal classification, highly urbanized city in the Metro Manila, National Capital Region of the Philippines. According to the 2020 census, it has a population of 4 ...

Pasig Pasig, officially the City of Pasig (), is a highly-urbanized city in the National Capital Region of the Philippines. According to the 2020 census, it has a population of 803,159 people. It is located along the eastern border of Metro Mani ...

Taguig Taguig (), officially the City of Taguig (), is the List of cities in the Philippines, fifth-most populous city in the Philippines situated on the eastern shores of Metro Manila, the national capital region. It is a center for culture, finance ...

and

Muntinlupa Muntinlupa (), officially the City of Muntinlupa (), is a Cities of the Philippines#Legal classification, highly urbanized city in the Metro Manila, National Capital Region of the Philippines. According to the 2020 census, it has a population o ...

, and the provinces of

Cavite Cavite, officially the Province of Cavite (; Chavacano: ''Provincia de Cavite''), is a Provinces of the Philippines, province of the Philippines located in the Calabarzon region. On the southern shores of Manila Bay and southwest of Manila, i ...

and Laguna, before ending in Canlubang in the south.

Fault segments

Relief Map of Metro Manila and nearby provinces showing the West and East Valley Fault Line

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

Quezon City Quezon City (, ; ), also known as the City of Quezon and Q.C. (read and pronounced in Filipino language, Filipino as Kyusi), is the richest and List of cities in the Philippines, most populous city in the Philippines. According to the 2020 c ...

and

and moves in a dominantly dextral strike-slip motion. The West Valley Fault segment extends from Doña Remedios Trinidad to Calamba and is long. The West Valley Fault is capable of producing large-scale

earthquakes An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they c ...

during its active phases with a

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

of 7 or higher. ;East Valley Fault The eastern segment, known as the ''East Valley Fault (EVF)'', moves in an oblique dextral motion. It extends about from Rodriguez to San Mateo in the province of Rizal.

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. The fault poses a threat of a large-scale

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

with an estimated

between 6–7 and as high as 7.6 to

and surrounding provinces, with a death toll predicted to be as high as 35,000 and some 120,000 or higher injured and more than three million needed to be evacuated. There are 99 private

village A village is a human settlement or community, larger than a hamlet but smaller than a town with a population typically ranging from a few hundred to a few thousand. Although villages are often located in rural areas, the term urban v ...

s and subdivisions inside 80

barangay The barangay (; abbreviated as Brgy. or Bgy.), historically referred to as ''barrio'', is the smallest Administrative divisions of the Philippines, administrative division in the Philippines. Named after the Precolonial barangay, precolonial po ...

s traversed directly by the fault, and it endangers 6,331 buildings in a span of , where the majority are houses with 19 schools included in the list.

References

External links

Valley Fault System (VFS): Marikina Quadrangle
– Philippine Institute of Volcanology and Seismology
High resolution West Valley Fault maps launched – RapplerPHIVOLCS 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. * {{SE Asia plates, state=expanded Geography of Bulacan Geography of Metro Manila Geography of Rizal (province) Geography of Laguna (province) Geography of Cavite Geology of the Philippines Marikina Seismic faults of Southeast Asia