MANILA - (UPDATED) Mt. Pinatubo in Zambales province has not shown any "anomalous activity" after a powerful quake rumbled across Luzon, state seismology office Phivolcs said Tuesday.

Monday afternoon's magnitude 6.1 tremor centered in Castillejos, Zambales. It was felt in Metro Manila and nearby provinces, worst in Pampanga where it flattened several buildings and left at least 16 dead.

"For now, wala pa naman po kaming nakikitang mga anomalous activities po sa Pinatubo," Phivolcs planning officer Carl Vincent Soriano told radio DZMM.

(We have not seen any anomalous activity in Pinatubo.)

Ishmael Narag, officer in charge of Phivolcs’ Earthquake and Tsunami Monitoring Division, also said the recent earthquake would not trigger any eruption of Mt. Pinatubo, since its last eruption was only in 1991.

“Unlikely na magkaron ng event kasi kakaputok lang ng Pinatubo volcano. It would take a long time for the magma levels to refill after the 1991 explosion,” Narag said in a press conference.

The ground activity was also concentrated on the volcano’s periphery, not on the crater, he added.

Mt. Pinatubo in Zambales last erupted in June 1991, leaving parts of Tarlac and Pampanga buried in lahar.

A separate 6.5-magnitude quake that rattled Eastern Samar Tuesday would not trigger volcanic eruptions nor tsunamis as it happened 63 kilometers beneath the surface.

• Luzon, Visayas quakes 'not related' - Phivolcs

State seismologists are monitoring plate movements along the Eastern side of the Philippines after Phivolcs monitored “several moderate events,” Narag said.

“The rate of movement of the PH Trench is faster. We are looking into it. Whether they (Zambales and Eastern Samar quakes) are connected we still could not say,” he said. - with a report from Katrina Domingo, ABS-CBN News