Pressure inside Mayon’s magma chamber may trigger eruption

LEGAZPI CITY, Philippines – Pressure inside the magma chamber of Mayon Volcano could trigger a violent eruption, the Philippine Institute of Volcanology and Seismology (Phivolcs) said yesterday.

Eduardo Villacorte, Phivolcs science research specialist, said about two million cubic meters of magma are inside the magma chamber some five kilometers below the volcano.

He said sulfur gas emission dropped to 308 tons on Thursday, way below the normal 500 tons per day, due to the lava dome blocking the crater.

“The inflation we observed before the 2000 eruption was at 20 millimeters based on precise leveling, but the present surface inflation at Mayon Volcano is still at 13 millimeters,” he said during a press briefing.

He said a 20-millimeter inflation shows that magma near the crater vent and the pressure depth are extensive.

“We have registered higher readings on the volcano’s inflation due to current pressurization, which reflects magma intrusion from the depth of the volcano,” Villacorte said.

But he said the ascent rate could change with the influx of new magma, which is moving at about one meter per hour.

“We can only downgrade the alert level unless all the parameters have registered a lowering trend because the volcano is still inflated,” he said.

Meanwhile, Phivolcs-Bicol chief volcanologist Ed Laguerta noted that based on Mayon’s past eruptions, a lava dome would always lead to an eruption.

“There was no phase in Mayon’s level of unrest that did not go into eruption phase,” he said.

Laguerta said each day becomes critical because of rapid changes in the behavior of the volcano.   – With Cet Dematera