Manila Mayor Francisco "Isko Moreno" Domagoso placed city agencies on high alert Monday following a magnitude 7.8 earthquake that struck off the coast of Mindanao, causing building collapses and triggering tsunami warnings in the south.

During a morning directional meeting, Domagoso ordered the Office of the Building Official, Manila City Disaster Risk Reduction and Management Office, Manila Department of Social Welfare, Department of Engineering and Public Works, Manila Police District, and Schools Division Office–Manila to immediately inspect public buildings and critical facilities.

"This is part of the regular preparation of the Manila local government whenever there is a strong earthquake in the country, even if it is far from Metro Manila," Domagoso said in a statement released by the city's public information office.

The mayor also ordered the preparation of a response team for potential deployment to General Santos City, a southern commercial hub where local authorities reported structural collapses and ongoing rescue operations.

The Philippine Institute of Volcanology and Seismology reported the tectonic quake struck at 7:37 a.m. at a depth of 33 kilometers (20 miles) off the coast of Maasim, Sarangani. The tremor prompted tsunami warnings across nine southern provinces and sent students fleeing from classrooms on the first day of the academic year.

Other jurisdictions also heightened their emergency posture Monday. The South Cotabato provincial disaster council raised its emergency operations center to a red alert status. Nationally, the Office of Civil Defense placed its operations centers on full red alert to expedite damage assessments and government assistance.

The Philippine Red Cross declared a full alert, deploying volunteers and ambulances to affected communities in North Cotabato, South Cotabato and Gingoog City.

Internationally, Indonesia's disaster management agency reported detecting minor tsunami waves in North Sulawesi. Malaysia issued a tsunami advisory for Sabah's east coast, while Japan raised the warnings to its south coast, from Ibaraki Prefecture to Okinawa Prefecture.