Scheduled preview · publishes Nov 15, 2026, 06:00 AM PHT
A magnitude 7.2 earthquake struck Bohol from a previously unrecognised fault. That is the most uncomfortable and most useful fact in the whole hazard set.
On 15 October 2013, a magnitude 7.2 earthquake struck Bohol. More than two hundred people died. Churches that had stood for centuries collapsed, roads split, and landslides closed routes across the island.
The most important detail for anyone reading a hazard report is this: the fault that ruptured was not on the map beforehand. PHIVOLCS subsequently named it the North Bohol Fault, and ground rupture appeared at the surface where nothing had been recorded.
A hazard screening reports the distance from your point to the nearest mapped active fault. The word "mapped" is doing a great deal of work.
Fault maps are built from surface evidence, trenching, historical records, and instrument data. Faults that have not moved in a long time, or whose surface expression is buried under sediment or vegetation, can be missed. Bohol is the clearest Philippine demonstration that the map is a record of what is known, not a complete inventory of what exists.
So read a fault distance this way:
This is the same class of caveat as coverage gaps in other layers. See a layer came back blank on your report.
Structure. Bohol's death toll was overwhelmingly from buildings failing, and the buildings that failed most dramatically were old unreinforced masonry: heavy stone and lime churches with no steel, built long before any code.
Modern reinforced concrete built to code and properly detailed performed far better. The lesson is not "avoid Bohol". It is that seismic safety is bought from a licensed structural engineer, not from a map. See most Philippine homes are not built for a big quake and the soft-storey problem.
Strong shaking triggered landslides across Bohol's hilly interior, cutting roads and isolating towns. On steep ground, an earthquake is a slope problem as well as a structural one.
Screen slope and mapped landslide susceptibility together for any inland Bohol address, and read them alongside the fault distance rather than separately.
Much of Bohol is limestone, which dissolves over time and can contain voids. Sinkhole is not a layer on a hazard screening because there is no national point-level dataset for it, and shaking can trigger collapse. Ask the MGB regional office. See sinkholes and limestone country.
The honest position is that hazard mapping is the best available public record and it is incomplete. Presenting it as complete would be more comfortable and less true.
That is precisely why a screening should be used to decide where to spend money on professionals, rather than as a substitute for them. It is the argument in is a low-cost hazard report enough.
PHIVOLCS is the authority on faults, earthquakes, and intensity, and the fault map is theirs. A hazard screening reports the distance to the nearest mapped active fault and terrain-based layers at your point. It does not detect unmapped faults, predict earthquakes, or assess a building.
CheckHazard does not replace a professional geotechnical or engineering survey.