A strong 6.6 magnitude earthquake hit the Phillipines Cotabato province on Tuesday, according to authorities.

No tsunami warning has been issued yet, authorities added.

The earthquake, which was tectonic in origin, can cause damage and that aftershock is expected, it added.

More than a dozen people were injured in M’lang town in Cotabato and Cagayan de Oro province, according to OCD.

Several cities and towns suspended classes to allow inspections of school buildings. At least three government and privately owned buildings damaged in another quake earlier this month sustained further damages and remained off-limits to the public.

Cotabato and its neighbouring provinces on Mindanao island are still recovering from the October 16 magnitude 6.3 earthquake that rattled the region, in which at least six people were killed and 167 injured.

The Philippines has frequent seismic activity due to its location along the Pacific “Ring of Fire”, registering quakes every day, though most are not felt.

Phivolcs records an average of 20 earthquakes a day and 100 to 150 earthquakes are felt per year.