LEGAZPI CITY — Increased seismic movement has been detected at Bulusan Volcano, with 90 volcanic earthquakes recorded by the monitoring network of the Philippine Institute of Volcanology and Seismology (Phivolcs).
In an advisory released Tuesday, the agency said the tremors were largely weak volcano-tectonic earthquakes associated with the fracturing of rocks beneath the volcano at depths of up to five kilometers.
Despite the increase in seismic activity, the volcano remains under Alert Level 0, which means a magmatic eruption is not anticipated at this time.
Phivolcs reported that other indicators of volcanic activity remain stable. Gas emission from the volcano’s vents ranged from very weak to moderate, while sulfur dioxide output was recorded at around 40 tons per day, considered below normal levels.
Monitoring also showed no significant ground swelling or thermal changes in nearby hot springs.
However, the agency pointed out that sporadic earthquake swarms have preceded past steam-driven eruptions of Bulusan.
Because of this possibility, the public has been reminded to stay away from the four-kilometer Permanent Danger Zone, particularly near vents located along the volcano’s south-southeastern slopes.
Sudden phreatic eruptions can eject ash and rocks and may trigger hazardous phenomena such as pyroclastic density currents, rockfalls, avalanches, and ashfall.
Local government units were advised to revisit contingency plans and strengthen preparedness measures should volcanic unrest intensify.
Phivolcs also urged aviation authorities to alert pilots about the risks of flying near the volcano’s summit due to potential ash emissions that could threaten aircraft safety.
The agency said it will continue round-the-clock monitoring of Bulusan Volcano.
elamigo/xf
