Are the earthquakes in Cebu, Baguio, and Davao Oriental connected?

In less than two weeks, three areas across the Philippines were jolted by an earthquake.

Residents of Cebu experienced a powerful 6.9 earthquake on Sept. 30. Nine days later, a 4.4 earthquake rattled residents of La Union and neighboring city Baguio on Oct. 9. 

And on Oct. 10, a magnitude 7.4 earthquake struck, lasting about 25 seconds, followed by a magnitude 6.9 aftershock, both severely impacting residents in Davao Oriental.

The consecutive earthquakes have prompted concerns that they might be connected, especially with the looming possible threat of so-called "The Big One."

Are the recent earthquakes connected?

The Philippine Institute of Volcanology and Seismology said that the recent earthquakes are not connected.

"Wala po silang koneksiyon, it's just that we have 180 active fault segments, and we also have six trenches, and there's always the possibility na isa o dalawa, or more active faults would generate earthquakes," Phivolcs Director Dr. Teresito Bacolcol explained during the press conference on Friday.

He added that the country experiences at least 30 earthquakes a day because of its active faults and trenches, although most of these are too weak to be felt.

"'Yung mga active faults natin are independent from each other… unless they are very close to each other, pwede magkaroon ng what we call stress transfer, but, in this case, masyado na pong malayo, from Cebu to La Union and Mindanao…wala po silang koneskyon,” Bacolcol said.

He further explained that aside from magnitude, other factors, like depth, are also considered when assessing how destructive an earthquake is. For example, Bogo City in Cebu province recorded a magnitude 6.9 earthquake with a depth of five kilometers, while the recent Davao Oriental earthquake, originally recorded with a 7.6 magnitude, was downgraded to 7.4. It had a depth of 23 km.