A series of earthquakes struck near Dalupiri Island and Calayan, Cagayan early Monday, with 17 tremors recorded as of 8 a.m., the Philippine Institute of Volcanology and Seismology (Phivolcs) said.
The strongest at magnitude 5.8 struck at about 1:18 a.m., about 25 km. northwest of Dalupiri Island in Calayan town.
All earthquakes were tectonic in origin, from shallow to moderately shallow, making the shaking widely felt across Cagayan and nearby provinces of Ilocos Norte and Ilocos Sur.
The sequence points to an active fault movement in the area.
Residents are urged to stay alert for possible aftershocks.