By Alexandria San Juan
Tremors have continued to jolt the Taal Volcano Island, which state volcanologists said signified movement underneath the volcano that could lead to eruptive activity.
In its latest bulletin, the Philippine Institute of Volcanology and Seismology (Phivolcs) said 123 volcanic quakes were recorded by the Taal Volcano Network from Tuesday morning to Wednesday morning, including three low-frequency events.
The Taal Volcano Network can record small quakes undetectable by the Philippine Seismic Network which plotted three volcanic earthquakes during the same period that registered at magnitudes 1.7 to 2.1 with one felt event at Intensity III.
According to Phivolcs, these tremblors signified magmatic activity beneath the Taal edifice that could lead to eruptive activity at the Main Crater where the volcano’s phreatic or steam-driven eruption occured last January 12.
On Wednesday, Phivolcs said Taal belched “moderate to voluminous white to dirty-white steam lade plumes”, reaching up to 600 to 800 meters tall that drifted northeast.
Phivolcs Director Renato Solidum Jr. earlier said that Taal’s steaming was normal and only indicated that there was an ongoing hydrothermal activity under the volcano wherein the groundwater was being heated by the magma that produced the steam or smoke.
Meanwhile, sulfur dioxide (SO2) emission on Wednesday slightly increased and was measured at an average of 64 tons per day compared from Tuesday when gas levels were too low to detect.
A higher level of SO2, which is a major gas component of magma, is being released when magma or molten rocks are near the surface of a volcano indicating a possible magmatic eruption.
Alert Level 3 is maintained over Taal Volcano which means there is a “relatively high unrest manifested by seismic swarms including the increasing occurrence of low-frequency earthquakes and/or harmonic tremors where some events are felt.”
With this, the state volcanology agency reminded the public that sudden steam-driven and even weak phreatomagmatic explosions, volcanic earthquakes, ashfall, and lethal volcanic gas expulsions can still occur and threaten areas within Taal Volcano Island and nearby lakeshores.
“Phivolcs recommends that entry into the Taal Volcano Island as well as into areas over Taal Lake and communities west of the island within a seven-kilometer radius from the Main Crater must be strictly prohibited,” the agency warned.
Local government units were also advised to assess areas outside the danger zone for damages and road accessibilities and to strengthen preparedness, contingency and communication measures in case of “renewed unrest.”
Phivolcs also advised the public to observe precautions due to ground displacement across fissures, frequent ashfall, and minor earthquakes while 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.