The double 5.7 magnitude earthquake that struck the northern Philippines within only a day apart could last for weeks or months. This, as the local government declared the town of Carmen in North Cotabato, worst affected by the tremor, under state of calamity.

The earthquakes, being tectonic in origin, will be the culprit for the long-felt duration of grounding movement.

"Strong earthquakes which are tectonic will cause aftershocks until the energy dissipates. In the case of Carmen which was hit by shallow quakes, the energy of the quake has little chance to dissipate when it reaches the surface," Jenila de Ocampo, Officer-in-charge of the Davao Seismic Station of the Philippine Institute of Volcanology and Seismology (Phivolcs), told local newspaper Davao Today.

In fact, she said, Phivolcs has recorded 80 aftershocks as of Sunday afternoon, but many were not felt. But they had expected it, Ms De Ocampo said.

Read: Philippines Hit Again, Just After a Day, with 5.7 Magnitude Earthquake

Mt. Apo Resurrecting?

But given the frequent tremors, affected residents of Carmen and surrounding areas wonder why the local government nor the Regional Disaster Risk Reduction and Management Council has not ordered for an evacuation.

Earthquakes tectonic in nature are basically colliding plates. It is mostly two plates rubbing against each other and then scraping because of jagged edges. The abrasion causes vibrating which we realise as earthquakes.

Some residents were theorising that Mt. Apo, the highest mountain in the country, could be showing signs of waking up. Either that, or a new volcano is being formed within the vicinity.

Ayna Sison, a resident in Kibudtungan village in Carmen town, claimed her grandfather discovered what seemed to look like a newly forming "inverted" volcano near the site where he lives.

"My grandfather said he heard a whistling sound like gas exiting from a chamber. When the sound stopped, he said, the earthquakes happened," Davao Today quoted Ms Sison.

But Ms Ocampo denied the claims. "There is no such thing." She further noted that data from Philvocs do not show any active fault line in the region.

However, she did say that the supposed discovery was within the Mt Apo complex.

But in a separate local report, North Cotabato Governor Emmylou Talino-Mendoza confirmed Phivolcs had indeed discovered "a new local fault line in the area."

North Cotabato was found to be sitting along the Cotabato Trench, which gave off a magnitude 8 earthquake on Aug. 16, 1976, leaving 8,000 people dead or missing due to a tsunami generated by the tremor, according to a report by BusinessWorld Online.

Another resident, Belgian national Joel Peeters, claimed it is "not usual" for the sleeping Mt Apo to resurrect, specially following the number of earthquakes, whether felt or unfelt, that the region has been experiencing lately.

Mr Peeters, who claimed to have been checking the earthquakes in the Philippines using European-Mediterranean Seismological Centre and US Geological Survey data listing, believed the series of quakes that struck Carmen town could "indicate that an inactive (volcano) is activating again, or forming, or that underground something is brewing."

Carmen Under State of Calamity

The country's Office of Civil Defense Region 12 has placed Carmen town under state of calamity following the two magnitude-5.7 quakes last Saturday and on Monday.

Local media outlets vary in their reports, but damages incurred from the double earthquakes were estimated to be between P59 million to P71 million (AU$1.5 million to AU$1.7 million).

At least 141 houses were damaged by the quake in the villages of Kimadzil and Kibudtungan, the hardest hit by the quakes.