The Philippine Institute of Volcanology and Seismology (Phivolcs) continued to record volcanic earthquakes in Mt. Pinatubo in Zambales and Taal Volcano in Batangas from 8 a.m., March 16 to 8 a.m., March 17.

Mt. Pinatubo registered 46 volcanic earthquakes, based on the volcano bulletin issued by Phivolcs on Wednesday, March 17.

It said the restive volcano remains under alert level 1, which means there is low-level unrest that may be related to tectonic processes beneath its edifice, but no imminent eruption is foreseen..

"Entry into the Pinatubo crater area must be conducted with extreme caution and should be avoided if possible," Phivolcs advised.

"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," it added.

Meanwhile, Taal Volcano recorded 55 earthquakes, including 44 episodes of volcanic tremor having durations of two to five minutes, during its 24-hour monitoring period.

A low-level background volcanic tremor that began at 7 p.m. last Tuesday, March 16 was also observed.

Phivolcs also observed "weak" emission of steam-laden plumes rising 50 meters.

Moreover, it measured a significant sulfur dioxide emission that averaged 689 tonnes/day last March 16, while temperature highs of 71.8 degrees Celsius and pH of 1.59 were measured from the main crater last March 4 and Feb. 11, respectively.

Ground deformation parameters also indicated a "very slow and steady inflation and expansion of the Taal region since after the January 2020 eruption."

"These parameters may indicate increased magmatic activity at shallow depths beneath the edifice," Phivolcs said.

Considering these observations, Phivolcs said Taal Volcano remains under alert level 2 due to "increased unrest." Its alert level was raised from 1 to 2 on March 9, 2021.

The possibility of sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall, and lethal accumulations or expulsions of volcanic gas can occur and threaten areas within the Taal Volcano island, it warned.

Phivolcs asked the public to avoid entering the volcano island, which is a permanent danger zone, especially the vicinity of the main crater and Daang Kastila fissure.

Local government units were advised to continuously assess and strengthen the preparedness of previously evacuated barangays around Taal Lake in case of renewed unrest.

Civil aviation authorities were also asked to advise pilots to avoid flying close to the volcano as airborne ash and ballistic fragments from sudden explosions and wind-remobilized ash may pose hazards to aircraft.