Metro Manila (CNN Philippines, June 19) — State volcanologists recorded hazardous pyroclastic flows—or streams of hot rock fragments, gas, and ash—on Mayon Volcano in the past 24 hours, even as no quakes were registered.
At least 628 people have been hurt due to Mayon’s unrest, the National Disaster Risk Reduction and Management Council (NDRRMC) reported on Monday. It did not explain how they were injured.
Over 20,000 residents have been moved to safer grounds and nearly 39,000 locals have been affected by the volcanic activity, NDRRMC added.
In its bulletin on Monday, the Philippine Institute of Volcanology and Seismology (Phivolcs) said it recorded pyroclastic flows from Mayon’s collapsed lava domes that lasted 3 minutes, and 265 rockfall events. Steam-laden plumes rose to 600 meters, it added.
“Pyroclastic density currents are perhaps the most hazardous events to local areas during explosive volcanic eruptions,” the British Geological Survey explained. “These hot, ground-hugging flows of ash and debris can travel at speeds of hundreds of metres per second, reaching many tens to hundreds of kilometres from the source.”
“The currents are inherently unpredictable and, as they propagate, they can morph in type between dense, clast-rich flows and dilute ash- and gas-rich surges, capable of detaching from the main body of the flow and surmounting topography,” it added.
Phivolcs said very slow effusion of lava from Mayon Volcano’s crater has continued in the past 24 hours. Sulfur dioxide emission averaged 889 tons per day on Sunday.
The agency said Mayon is still on Alert Level 3, warning local authorities of possible hazardous eruption of the volcano within weeks or even days.
State volcanologists are monitoring parameters including increase in lava extrusion and sulfur dioxide emission, seismic activity, and edifice swelling before raising Mayon’s alert to Level 4.
The province of Albay is under a state of calamity and local authorities have evacuated residents within the 6-kilometer radius permanent danger zone.
