The Big One

The Big One: What Filipinos Need to Know Beyond the Hype

 

The "Big One" is a term that has become synonymous with fear in the Philippines, but it's more than a rumor. It refers to a potential catastrophic earthquake along the West Valley Fault (WVF) that could severely impact Metro Manila and nearby provinces. The Philippine Institute of Volcanology and Seismology (PHIVOLCS) regularly reminds the public about this seismic threat, emphasizing preparedness over panic. 

What is the "Big One" Earthquake?

The "Big One" is not a specific, impending earthquake with a set date but a worst-case scenario. It describes the maximum probable movement of the West Valley Fault System, which could generate a massive 7.2 magnitude earthquake. The WVF is an active fault that runs approximately 100 kilometers through the Greater Manila Area, including parts of Quezon City, Marikina, Pasig, Makati, Taguig, and Muntinlupa, as well as nearby provinces. 

The West Valley Fault: A Ticking Clock?

According to PHIVOLCS, the West Valley Fault has a history of major movements occurring roughly every 400 to 600 years. 

The last significant movement of the fault was recorded in 1658, making a major movement possible within our lifetime.

While this data indicates that the fault is "ripe" for a major movement, it does not mean an earthquake is "overdue".

The 2025 rumors about a specific date were debunked by PHIVOLCS as lacking any scientific basis. 

The Map: Identifying Risk Zones

PHIVOLCS provides detailed maps to help the public identify areas traversed by the West Valley Fault.

The Valley Fault System (VFS) Atlas, first launched in 2015, shows the fault's exact path.

The PHIVOLCS FaultFinder, a web application, allows users to check the proximity of active faults to their location.

These tools are vital for land-use planning, risk assessment, and understanding which communities are most vulnerable. 

What Will Happen During the "Big One"?

The potential impacts of a 7.2 magnitude earthquake from the WVF are extensive and devastating, as outlined in the 2004 Metro Manila Earthquake Impact Reduction Study (MMDIRS) and subsequent updates: 

Infrastructure collapse: A 2025 study projected the collapse of over 168,000 residential buildings, with a significant number of high-rise structures also at risk.

High casualties: Estimates suggest tens of thousands of casualties, primarily from collapsing structures and subsequent fires.

Widespread fires: The earthquake could trigger fires, causing additional deaths and destruction.

Liquefaction: Soil liquefaction in certain areas could cause ground deformation, further damaging infrastructure and making rescue efforts difficult.

Isolation of affected areas: Damaged roads and communication networks could isolate communities, hampering relief operations. 

What PHIVOLCS Says About the "Big One"

PHIVOLCS, the lead government agency on seismic activity, has a clear message: prepare, don't predict.

No prediction technology: PHIVOLCS has repeatedly stated that no existing technology can predict the exact time and location of an earthquake.

Debunking rumors: The agency actively debunks false earthquake predictions circulating on social media, emphasizing that they are not a reliable source of information.

Focus on preparedness: PHIVOLCS stresses the importance of community and individual preparedness through regular drills, such as the Nationwide Simultaneous Earthquake Drill (NSED).

Local "Big Ones": Experts at PHIVOLCS also emphasize that other regions in the Philippines are vulnerable to their own "Big One" scenarios from different active faults, not just Metro Manila. 

How You Can Prepare for the Inevitable

Since the "Big One" is a scientific certainty over the long term, preparedness is the most effective strategy.

Secure your home: Bolt down heavy furniture, appliances, and water heaters to prevent them from toppling over.

Prepare an emergency kit: Assemble a "Go Bag" with essentials like food, water, a first-aid kit, a flashlight, batteries, and important documents.

Know your evacuation plan: Identify safe spots inside your home and a designated meeting point for your family outside.

Practice "Duck, Cover, and Hold On": Drill this procedure with your family so it becomes an automatic response during an earthquake.

Stay informed: Follow official advisories from PHIVOLCS and local disaster offices. Do not spread unverified claims. 

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