The magnitude 7.4 earthquake that struck off the coast of Manay, Davao Oriental on Friday, October 10, and the magnitude 6.9 tremor that struck Cebu 10 days earlier, are completely unrelated, Phivolcs said.
At a press conference, Phivolcs Director Teresito Bacolcol dismissed concerns that the earthquake this morning was triggered by the earlier tremors in Cebu, explaining that these come from entirely different fault systems.
“All independent earthquake generators… Walang kinalaman yung isa sa Philippine Trench dun sa Bogo Bay Fault (The Philippine Trench has nothing to do with Bogo Bay Fault),” Bacolcol said.
Both faults are “independent” and located far from each other geographically. Bacolcol added: “The activity of one will not induce or trigger the acitivity of the other.”
The Philippine Trench, one of six active trenches around the Philippines, was the origin of Friday’s quake that struck 9:43 a.m., prompting tsunami warnings. At least two people have been reportedly killed.
The September 30 Cebu quake came from the Bogo Bay Fault, an underwater fault that hadn’t moved significantly in over 400 years.
Bacolcol pointed to historical patterns showing the Philippine Trench regularly generates powerful earthquakes. A magnitude 7.5 quake hit the same area in 1921, followed by an 8.3 tremor in 1924, a 7.2 in 1929, and a 7.6 in 1952. All were along the Philippine Trench, Bacolcol said.
The Cebu earthquake devastated the municipalities of Bogo, Daanbantayan, and Medellin, killing at least 74 and completely destroying over 5,000 homes.
As of October 10, around 8,000 persons remain displaced.
Friday’s Davao quake was felt across Mindanao and as far as Cebu City, where residents still on edge from last month’s earthquake felt Intensity IV-level shaking. Over 200 aftershocks followed the Davao tremor, with the strongest so far reaching magnitude 5.8.