FILE - The crater lake formed after Mt. Pinatubo erupted in 1991, shown in this file photo, has become a major attraction for outdoor enthusiasts, with trails opened in Tarlac and Zambales provinces.
A "weak explosion" was recorded at Mt. Pinatubo on Tuesday, said the Philippine Institute of Volcanology and Seismology.

In its latest bulletin, Phivolcs said the explosion was recorded between 12:09 p.m. and 12:13 p.m.

"The event produced a plume that was detected by the Himawari-8 Satellite and reported to Phivolcs by the Tokyo Volcanic Ash Advisory Center," said Phivolcs.

From Tokyo Volcanic Ash Advisory Center

"The seismic and infrasound signals are not typical of known volcanic processes and are currently being evaluated together with other potential sources," it added.

Phivolcs explained that there has only been very low seismic activity in the past days. The Pinatubo Crater Lake yields low diffuse volcanic carbon dioxide flux at only 257 tonnes per day.

However, Phivolcs warned the public not to enter the volcano's vicinity at this time.

Local government units were advised to prohibit entry into Pinatubo Crater "until the source of the above explosion event has been determined and to report to us any related information. "

"Communities and local government units surrounding Pinatubo are reminded to be always prepared for both earthquake and volcanic hazards and to review, prepare and strengthen their contingency, emergency, and other disaster preparedness plans," Phivolcs said.

Mt. Pinatubo last erupted on June 15, 1991, and was considered the second-largest eruption of the 20th century.