Metro Manila (CNN Philippines, October 31) — Another strong earthquake jolted parts of Mindanao on Thursday morning.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said a magnitude 6.5 earthquake was recorded at 9:11 a.m. in Tulunan town in Cotabato — the same area where the deadly magnitude 6.6 tremor hit on Tuesday.

A "destructive" Intensity VII shaking was felt in Tulunan, Cotabato; Kidapawan City; Sta. Cruz, Matanao, Bansalan, and Magsaysay in Davao del Sur. A "very strong" Intensity VI was also experienced in Tampakan, South Cotabato.

Three people from Makilala town died as a result of the quake, the Department of Social Welfare Development said.

Phivolcs Science Research Specialist Erlinton Olavere said this is not an aftershock of the 6.6- and 6.1-magnitude tremors on Tuesday. He explained that for a quake to be considered an aftershock, the magnitude should be going down gradually. He also raised the possibility of more earthquakes in the area.

"Siguro madali natin sabihin kung magnitude 4 or 3 na it's an aftershock. Almost same ang energy na binibigay ng lindol, so ang worry namin baka mayroon pang pwedeng mas malaki," he told CNN Philippines.

[Translation: The earthquakes are of similar magnitude, so our worry is that there may be a stronger one coming.]

He said five active faults in the area are causing the series of strong earthquakes.

"Gumalaw ang isang fault, then nagre-react din ang isang fault. Kaya ang area, mapapansin natin ang malalakas na (lindol). Magnitude 6.6, then we have magnitude 6.1, then we have a 6.5 today. Two weeks before nagkaroon din tayo ng 6.3. Interrelated. Kumbaga, gumagalaw. Medyo active ang faults sa area," he said.

[Translation: The faults are reacting to each other, if you keep track of the pattern of strong earthquakes in the past weeks. These are interrelated. The faults in the area are active.]

Authorities are still assessing the damage. A portion of Eva's Hotel in Kidapawan City reportedly collapsed due to the strong tremor.

Mwanwhile, the first two floors of four-storey condominium Ecoland 4000 in Davao City also collapsed, Davao City PIO Jefry Tupas said.

Parts of Mindanao are still reeling from the quake on Tuesday, which left 10 dead and 395 people injured.

CNN Philippines' correspondents David Santos, Carolyn Bonquin and stringer Abner Francisco contributed to this report.