Inactive Segment of South Bohol Offshore Fault Shows Movement

INACTIVE SEGMENT OF SOUTH BOHOL OFFSHORE FAULT SHOWS MOVEMENT

A segment of the South Bohol Offshore Fault that has not moved yet is being closely monitored by the Philippine Institute of Volcanology and Seismology (Phivolcs) as it has the potential to trigger a magnitude 6.5 to 7 earthquake in Bohol.

According to Engr. Nolan Evangelista of Phivolcs Bohol, the inactive segment is located offshore from Garcia-Hernandez, Valencia, and Dimiao.

The entire South Bohol Offshore Fault stretches from Anda to Dauis-Panglao and then to Siquijor.

However, other segments of the fault have been active, with 19 movements recorded in October, the strongest of which was a magnitude 4.2 earthquake.

"It’s better that the fault is active because it means that the stress is being released," Evangelista said.

The inactive segment of the fault is more concerning because it means that the stress has been building up. If it were to move, especially without any small tremors, the force released would be strong, Evangelista said.

Using a formula adopted worldwide, if the segment is around 70 kilometers long, it could potentially release an earthquake with a magnitude of 6.5 to 7.

Aside from the South Bohol Offshore Fault, there is also the East Bohol Fault, which runs through the mountains of Loay and Lila and then to Sierra Bullones. This fault has been active.

The newly discovered North Bohol Fault in Inabanga was responsible for the 7.2 magnitude earthquake that struck on October 15, 2013.