Volcanic earthquakes, magmatic activity in Taal Volcano – Phivolcs
by Joseph Almer PedrajasThe Philippine Institute of Volcanology and Seismology (Phivolcs) continues to monitor activities of the Taal Volcano after recording several volcanic earthquakes which signify magmatic activity.
In its Friday bulletin, Phivolcs said that the Philippine Seismic Network (PSN) plotted a total of seven volcanic earthquakes that registered at magnitudes M1.7-M2.5 since 5 a.m. of Wednesday to 5 a.m. of Friday.
The Taal Volcano Network, which can record small earthquakes undetectable by the PSN, recorded 116 volcanic earthquakes, including two low-frequency events over the past 24 hours.
Phivolcs said that “these earthquakes signify magmatic activity beneath the Taal edifice that could lead to eruptive activity at the main crater.”
Phivolcs also pointed out that the activity in the volcano’s main crater in the past 24 hours has been characterized by moderate emission of white to dirty white steam-laden plumes 500-700 meters tall that drifted southwest. It is 200 meters higher than the previous emission.
Sulfur dioxide emission was below instrumental detection, it added.
Almost a week after Taal’s alert level four was lowered, Alert Level 3 remains in effect over Taal Volcano. This means that sudden steam-driven and even weak phreatomagmatic explosions, volcanic earthquakes, ash fall, and lethal volcanic gas expulsions can still occur and threaten areas within the Taal Volcano Island and nearby lakeshores.
Phivolcs recommended that entry into the Taal Volcano island, Taal Lake, and communities west of the volcano island within a 7-km. radius from the main crater must be strictly prohibited.
Local government units were advised to assess areas outside the 7-km. radius for damages and road accessibilities and to strengthen preparedness, contingency, and communication measures in case of renewed unrest.
People were also advised to observe precautions due to ground displacement across fissures, frequent ash fall, and minor earthquakes.
Communities beside active river channels, particularly where ash from the main eruption phase has been thickly deposited, should increase vigilance when there is heavy and prolonged rainfall since the ash can be washed away and form lahars along the channels.
Civil aviation authorities were 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 aircrafts.