A second powerful earthquake struck off the coast of Manay, Davao Oriental at 7:12 PM today, registering a magnitude of 6.8.
The tremor occurred just hours after a magnitude 7.4 quake hit nearly the same area, prompting PHIVOLCS to classify the event as a ‘doublet earthquake’-a rare seismic phenomenon involving two distinct but closely timed major quakes in the same region.
According to PHIVOLCS Director Dr. Teresito C. Bacolcol, both quakes were triggered by stress along the Philippine Trench.
The epicenter of the second quake was located 36 kilometers southeast of Manay (07.49°N, 126.82°E) at a depth of 10 kilometers. It was tectonic in origin and generated strong ground shaking across multiple provinces.
A tsunami warning was issued for Surigao del Sur, Davao Oriental, and Surigao del Norte.
Coastal residents were urged to evacuate immediately, as waves reaching one meter or higher above normal sea levels could arrive within the hour.
PHIVOLCS stated that the tsunami watch is in effect between 7:12 PM and 11:12 PM.
Reported intensities included:
Intensity VI: Manay, Davao Oriental
Intensity V: Baganga, Boston, Caraga, Cateel, and Tarragona, Davao Oriental
Intensity IV: Davao City, Mati City, Bislig City, and parts of Davao de Oro
Intensity III to I: Felt across Leyte, Southern Leyte, Cotabato, Sultan Kudarat, Dinagat Islands, and parts of Eastern and Northern Samar
Doublet earthquakes are not aftershocks, but two separate main shocks of similar magnitude occurring close in time and location.
Past examples include the 2023 Hinatuan sequence (M7.4 on Dec 2 and M6.8 on Dec 4) and the 1992 Manay doublet (M7.1 and M7.5), both linked to the Philippine Trench.
Cebu and Davao quakes not directly related, but risk remains
The recent magnitude 6.9 earthquake in Cebu and the magnitude 7.4 tremor in Davao Oriental were caused by separate fault systems and are not geologically connected, according to PHIVOLCS Director Dr. Teresito Bacolcol.
The Cebu quake originated from the Bogo Bay Fault, while the Davao quake was triggered by movement along the Philippine Trench.
Despite the lack of connection, Bacolcol emphasized that the possibility of stronger quakes cannot be ruled out. PHIVOLCS continues to monitor seismic activity across the country.
Historically, major earthquakes-like Japan’s 2011 Tohoku disaster-have been preceded by strong foreshocks. In that case, a magnitude 7.3 quake struck two days before the magnitude 9.1 mainshock. While not all seismic clusters lead to a larger event, preparedness remains essential.