The PHIVOLCS FaultFinder Map & App

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The Big One, we hear this a lot for the past few years from different government agencies, representatives/speakers, and politicians. This is the expected long-overdue 7.2-magnitude earthquake that may hit the National Capital Region. To help prepare for it, the Philippine Institute of Volcanology and Seismology has provided an official FaultFinder interactive map.

The PHIVOLCS FaultFinder map displays all the different faults located in the Philippines, in particular, the Valley Fault System or VFS (formerly known by its inaccurate label “Marikina Fault Line”). This is an official map and data, as such it is the most reliable information we have.

But before we check these fault lines, what exactly is The Big One? Where will it be coming from? When will it happen?

Here is a bulleted list of information that will help us.

  • What is The Big One

    It is a movement of the Valley Fault System (“VFS”), that can generate 6 to 7 magnitude and as high as 7.6[1].

  • When will it hit?

    It is understood that the VFS moves every 400 to 600 years, and has moved 4 times in the last 1,400 years (which means it moved no less than every 350 years in that span). The last time was back in 1658, 359 years ago counting from the date of this post.

    If you want to know when exactly it will hit, there is no possible way to know. We can not even measure the pressure building up in the fault lines, much less know when that pressure will pop to relieve itself.

  • Where will be the epicenter?

    The VFS is divided into two: the West Valley Fault System and the East Valley Fault System. The latter is shorter (10-km) that traverses Rodriguez and San Mateo in the province of Rizal which can generate a 6.2-magnitude earthquake.

    However, the former is a 100-km long fault line from Angat Dam Reservoir at Barangay San Lorenzo, Norzagaray, Bulacan; to Mabato, Calamba, Laguna (3.3 km from Tagaytay Highlands Golf & Country Club; 4.3 km from Tagaytay Midlands; 4.5 km from People’s Park in the Sky [note that People’s Park is at the highest point in the area]). Thus, the epicenter can be anywhere from that 100-km fault line (and we should expect aftershocks or quake swarms anywhere as well).

The PHIVOLCS FaultFinder Map

To know where the West Valley Fault System is and help you prepare, the Philippine Institute of Volcanology and Seismology or PHIVOLCS, created an interactive map for the public to use. It can be accessed by visiting clicking this link:

The Android version, “The PHIVOLCS FaultFinder” can be installed from Google Play.

Recommended reads

Part of the Earthquake Preparedness Philippines series.

    The PHIVOLCS Fault Finder Map
    Article Name
    The PHIVOLCS Fault Finder Map
    Looking for a map where the Valley Fault System crosses Metro Manila, Bulacan, Cavite, and Laguna in the Philippines? Check this map.

    CC BY-SA 4.0 The PHIVOLCS FaultFinder Map & App by ᜌᜓᜃᜒ (Yuki|雪亮) is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. Permissions beyond the scope of this license may be available at Legal Notice.

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