Steam emissions observed at Taal's main crater, fissure vents

Almost four weeks since its first eruption, steaming is still observed at Taal Volcano and Alert Level 3 remains in place, according to PHIVOLCS on Friday.

In the past 24 hours, moderate emission of white to dirty white steam-laden plumes, rising 200 to 300 meters high, was observed in the volcano's main crater.

The fissure vents along the Daang Kastila trail are weakly giving off steam, too, according to PHIVOLCS.

PHIVOLCS said that the Taal Volcano Network detected 118 volcanic earthquakes, including five low-frequency events and one harmonic tremor that lasted less than three minutes.

Low-frequency earthquakes are "caused by cracks resonating as magma and gases move toward the surface" while harmonic tremors are continuous rhythmic earthquakes that "often precede or accompany volcanic eruptions," according to the United States Geological Survey.

"These earthquakes signify magmatic activity beneath the Taal edifice that could lead to eruptive activity at the main crater," PHIVOLCS said.

Meanwhile, there was no trace of sulfur dioxide emitted by the volcano for the second day in a row. The presence of this gas indicates the upward movement of magma towards the surface, according to state volcanologists.

PHIVOLCS warned the public that "sudden steam-driven and even weak phreatomagmatic explosions (involving both magma and water), volcanic earthquakes, ashfall, and lethal volcanic gas expulsions can still occur and threaten areas within Taal Volcano Island and nearby lakeshores."

It advised that the Taal Volcano Island and communities west of the island within a seven-kilometer radius from the main crater should remain off-limits.

Areas outside the seven-kilometer radius have to be assessed by authorities for damages and road accessibilities. Returning residents must also be prepared to evacuate in case of the volcano's renewed unrest, it added.

Further, those living beside active river channels with thick deposits of volcanic ash from Taal's previous eruption must be vigilant for possible lahar when there is heavy and prolonged rainfall.

Aircraft must also avoid flying close to the volcano due to hazards that may be posed by airborne ash and ballistic fragments from sudden explosions and wind-remobilized ash, PHIVOLCS said. —KBK, GMA News