Why the 'Big One' becomes more likely as 2058 approaches
MANILA, Philippines — A major movement of the West Valley Fault is inevitable either in the short or long term, but there is no reason for panic, only for preparedness and planning.
Phivolcs Director Teresito Bacolcol said on Monday, October 13, that the so-called "Big One," a projected magnitude 7.2 earthquake that could affect Metro Manila and nearby provinces, is part of the West Valley Fauly's natural long-term cycle, not an imminent prediction.
Bacolcol said the Philippines is considered "ripe" for a major earthquake because the West Valley Fault is within its expected timeline for its next movement.
In an interview with ANC, he explained that the fault last moved in 1658 and typically generates large earthquakes every 400 to 600 years.
"If you consider the lower boundary, which is 400 years — so 1658 plus 400 years, that would be 2058," Bacolcol said. "It means that as we get closer to 2058, the probability of this thing recurring is increasing."
Bacolcol, however, stressed that 2058 is not a prediction but simply a reference point.
"Of course, it doesn’t mean that by 2058, it will happen. It could be earlier or it could be later, or it could even be on the upper boundary, which is 600 years," he said.
He added that determining an exact date is impossible: the best that science can do is identify an interval during which another large movement becomes more likely.
Understanding recurrence, not prediction
Bacolcol said that the projection is not a forecast of a specific date, but an analysis based on the fault’s historical pattern.
"That’s the most that we can do for now — give an interval as to when there will be another big event," he said. "That’s the reason why we’re saying that we’re ripe for the Big One."
The West Valley Fault runs roughly 100 kilometers through Bulacan, Metro Manila and Calabarzon, forming one of the country’s most closely monitored fault systems.
Government agencies continue to urge households, schools, and offices to prepare emergency kits, identify safe evacuation routes, and reinforce structures as precautionary measures — actions that remain useful regardless of when a major quake occurs.
Recent quakes not connected to the West Valley Fault
Addressing those fearing that powerful earthquakes have become a pattern over the past weeks, Bacolcol said the recent earthquakes in La Union, Zambales, Cebu, Surigao and Davao are unrelated to the West Valley Fault.
"Those earthquakes came from different earthquake generators," he said.
He explained that:
- The La Union quake was generated by the Philippine Fault,
- The Zambales event originated from the Manila Trench,
- The Cebu quake was caused by the Bogo Bay Fault, and
- The Davao and Surigao shaking came from the Philippine Trench.
The difference is with the attention people give to the occurrences. The Phivolcs chief explained the country experiences frequent and sometimes consecutive earthquakes because the Philippines has 180 active faults.
Bacolcol added that such activity is normal in a tectonically active region like the Philippines.
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