A strong offshore earthquake affected parts of Mindanao on Christmas day. Philippine Institute of Volcanology and Seismology (Phivolcs) chief Dr. Rene Solidum told radio dzMM Thursday that a 6.1 magnitude earthquake affected parts of General Santos City, Kidapawan, Cotababo City, and Davao City at 11:20 a.m.. 

The earthquake was intensity 5 in General Santos City. Based on the Phivolcs Earthquake Intensity Scale (PEIS), intensity 5 means it is "generally felt by most people indoors and outdoors." There is "strong shaking and rocking felt throughout a building" and "hanging objects swing violently."

Under the PEIS, intensity 10 is completely devastating and intensity 1 is scarcely perceptible. Solidum said he does not expect “significant damage” due to the earthquake but said there will likely be aftershocks. 
He said the earthquake was 85 kilometers off General Santos City and 184 kilometers below the surface.
 

According to the US Geological Service website, the earthquake was 55 kilometers southeast of General Santos City and 145 kilometers south of Davao.The USGS reported the earthquake’s magnitude was 6.2 and with a depth of 207.5 kilometers.