Metro Manila (CNN Philippines, August 11) — A magnitude-6.3 earthquake shook Nasugbu town in Batangas and other areas in Luzon Friday afternoon.

The earthquake struck an area off Nasugbu, around 100 kilometers away from Manila, at 1:28 p.m., the Philippine Institute of Volcanology and Seismology (Phivolcs) said.

It said the quake was tectonic in origin – or there was a movement in the Earth's crust – with a depth of 160 kilometers. Aftershocks are expected.

At 2 p.m., Phivolcs said "no destructive tsunami threat exists based on available data."

Phivolcs Senior Science Research Specialist Rhommel Prutas told CNN Philippines that since the earthquake was "very deep," it is not likely to cause damage.

According to Phivolcs, a "moderately strong" Intensity IV was felt in the towns of Nasugbu, Calatagan, and Balayan in Batangas; Calapan, Sablayan, and Mamburao in Occidental Mindoro; cities of Manila, Parañaque, Pasig, and Taguig in Metro Manila; Maragodon, Noveleta, and Dasmariñas in Cavite; Floridablanca, Pampanga; Olongapo City; and Subic and Iba, Zambales.

The tremor prompted people to evacuate buildings to find a safe zone, and several schools and offices to suspend classes and work.

READ: #WalangPasok: August 11 class, work suspensions

Intensity III was also felt in Puerto Galera, Oriental Mindoro; San Jose, Occidental Mindoro; Tagaytay City; Canlubang, Laguna; Indang and Alfonso, Cavite; Bocaue, Malolos, Obando, and Balagtas, Bulacan; Dagupan City; Dau, Pampanga; Lingayen, Pangasinan; Bagac, Bataan; Baguio City; Cainta and San Mateo, Rizal; and in the cities of Pateros, Quezon, Makati, San Juan, and Marikina in Metro Manila.

Intensity II was reported in Sta. Rosa, Laguna; Gasan, Marinduque; Magalang and Sto. Tomas, Pampanga; and Tanauan, Batangas; and Intensity I in Talisay, Batangas; Pantabangan, Nueva Ecija; Meycauayan, Bulacan; and Atok, Benguet.

"We expect damage if the intensity is around 6," Prutas said.

Instrumental intensities – though not necessarily felt by residents – were also recorded by Phivolcs equipment in Quezon City; Calumpit and San Ildefonso, Bulacan; and Tagaytay City (III); Lucban, Quezon (II); and Magalang, Pampanga (I).

This is a developing story. Please refresh page for updates.

CNN Philippines' Gerg Cahiles contributed to this report.