Phivolcs detects weak phreatic activity at Taal; magmatic eruption unlikely

MANILA, Philippines — State volcanologists detected weak phreatic or steam-driven eruption from the main crater of Taal Volcano late Monday.

According to a Tuesday advisory from the Philippine Institute of Volcanology and Seismology (Phivolcs), current volcanic earthquake activity and ground deformation indicate that unrest is unlikely to progress into magmatic eruption or eruption driven by magma coming from deep down the volcano.

"Weak phreatic activity is likely driven by the continued emission of hot volcanic gases at the Taal Main Crater and could be succeeded by similar events," the state volcanologist explained.

Phreatic eruption occurs when water beneath the ground or on the surface is heated by volcanic activity.

The phreatic eruption at Taal produced steam-laden plumes that rose 600 meters above the main crater before drifting west, according to Phivolcs' advisory.

Alert Level 1 is maintained over the Taal Volcano, which means it is in abnormal condition.

Phivolcs reminded the public that Alert Level 1 prevails over Taal Volcano, which means that it is still in "abnormal condition" and "should not be interpreted to have ceased unrest nor ceased the threat of eruptive activity."

"At Alert Level 1, 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," Phivolcs said. 

"Furthermore, degassing of high concentrations of volcanic SO2 continues to pose the threat of potential long-term health impacts to communities around Taal Caldera that are frequently exposed to volcanic gas," it added.