The Valley Fault System, known before as the Marikina Valley Fault System is a group of dextral strike-slip fault which extends from San Mateo, Rizal to Taguig City on the south; running through the cities of Makati, Marikina, Paranaque and Taguig.
The fault has two segments, the West Valley Fault and East Valley Fault both located in the city of Marikina.
The west segment, known as the Western Marikina Fault was one of the two fault segments of the Valley Fault System which runs through the cities of Marikina, Pasig, Muntinlupa and moves in a dominantly a sinistral and dextral strike-slip motion.
The West Fault is capable of producing large scale earthquakes on its active phases with a magnitude of 7 or higher.
The Philippine Institute of Volcanology and Seismology has reported that the Marikina West Valley fault line, one of the active faults in the country, is ripe for movement because it has not moved for 200 years.
Phivolcs said the possibility of a Magnitude 7.2 earthquake is not far-fetched.
A Metro Manila Earthquake Impact Reduction Study earlier revealed that 7 out of 17 cities in Metro Manila will suffer the most damage and casualties if a massive earthquake occurs at the West Valley fault.
The 7 cities are Marikina, Quezon, Pasig, Makati, Pateros, Taguig and Muntinlupa.
Due to the recent Magnitude 7.2 earthquake that hits Bohol and Cebu City on Tuesday, October 15, 2013, Phivolcs and the MMDA reviewed their emergency plans and measures in case the same strength of earthquake will hit Metro Manila.
According to the studies conducted by Phivolcs, the magnitude 7.2 earthquake will affect Metro Manila once the dangerous West Valley Fault will start to move.
The West Valley Fault stretches from the Province of Bulacan to the Province of Laguna in the south traversing Metro Manila areas.
The Philippines is located in the world-renowned Pacific Ring of Fire, an area where large numbers of volcanic eruptions and earthquake occur.
This belt of oceanic trenches and volcanic arcs has been ripe for the past few years and it’s ready to unleash havoc across the Pacific Rim.
The West Valley Fault Line, also known as the “Marikina Valley Fault System,” moved every 400 years. The last time that fault line moved was way back the year 1658.
In preparation for the West Valley Fault’s movement the Metro Manila Development Authority (MMDA) prepared four areas of Metro Manila as evacuation centers on their “Oplan Metro Yakal.”
The program will make use four areas of NCR as evacuation centers, they have also prepared the Pasig River as the best alternative route to designated evacuation centers.
These are all man-made plans as far as what the comprehensive ability can reach at the moment. No one can really be sure of really happened in the past, say 400 years ago or in the year 1658, which could attribute explicitly without any error about the faults on earth.
Therefore, predictions are always the favorite past time of men since time first began.