A moderately strong earthquake measuring magnitude 5.1 struck off the coast of Palawan on Tuesday afternoon, June 11, despite the absence of active faults in the province, according to the Philippine Institute of Volcanology and Seismology (PHIVOLCS).
PHIVOLCS recorded the shallow quake at 2:58 p.m. with its epicenter located 91 kilometers southeast of Roxas, Palawan, and an estimated depth of 26 kilometers. The highest felt intensity was reported in Roxas, Palawan, at Intensity III (weak).
PHIVOLCS explained that the earthquake was generated by a “reverse fault,” characterized by mainly vertical movement. The earthquake occurred offshore within the northwest Sulu Sea basin, where high-resolution bathymetric data suggest deformation of the seafloor due to potential reverse faults in this region.
“These offshore faults are potential sources of earthquakes,” PHIVOLCS stated.
The agency reiterated that although there are no known active faults in Palawan, the province may still be affected by earthquakes and tsunamis from nearby faults and trenches.
No immediate reports of damage or casualties have been received, and PHIVOLCS continues to monitor the situation. Residents in the affected areas are advised to remain vigilant and follow any advisories issued by local authorities.
According to PHILVOCS, this highlights the importance of earthquake preparedness in regions considered seismically inactive, underscoring that the absence of active faults does not equate to immunity from seismic events.