The Philippine Institute of Volcanology and Seismology (Phivolcs) has recorded a series of earthquakes accompanied by rumbling sounds from Taal Volcano shortly before 4 a.m. on Wednesday, Nov. 3.
In an advisory issued on Wednesday evening, Phivolcs said its monitoring station in Batangas was able to detect a series of volcanic earthquakes at 3:47 a.m.
The quakes, which were felt at Intensity I in Brgy. Banyaga, Agoncillo, Batangas, were accompanied by rumbling sounds.
"The event registered a maximum magnitude of 2.9 and lasted two minutes based on the seismic record and produced a series of four short-lived plumes less than a kilometer tall based on thermal camera recording. The seismic signal characteristics of the event are similar to phreatomagmatic bursts that occurred in July 2021," Phivolcs said in its advisory.
A phreatomagmatic eruption is caused by magma coming into contact with groundwater.
Phivolcs said the Taal Volcano remains under Alert Level 2, which means that the active volcano continues to manifest "increased unrest."
"At Alert Level 2, sudden steam- or gas-driven explosions, volcanic earthquakes, minor ashfall, and lethal accumulations or expulsions of volcanic gas can occur and threaten areas within and around TVI," it pointed out.
The volcano has been under Alert Level 2 since July 23, 2021.
Phivolcs reiterated that entry into the Taal Volcano Island, which is a permanent danger zone, especially the vicinities of the main crater and the Daang Kastila fissure, is strictly prohibited.
Boating on Taal Lake is also be prohibited, it added.
Phivolcs advised the concerned local government units to continuously assess and strengthen the preparedness of previously evacuated barangays around Taal Lake in case of renewed unrest.
"Civil aviation authorities must 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," it added.