25 M cubic meters of magma detected below Mayon’s summit

LEGAZPI CITY, Philippines — At least 25 million cubic meters of eruptible magma have been detected 2.4 kilometers below the summit of Mayon Volcano, just waiting for enough pressure to trigger an eruption, the Philippine Institute of Volcanology and Seismology (Phivolcs) warned yesterday.

According to Phivolcs, the magma is in a shallow chamber at the foot of Mayon and the volume is comparable to three years of magma accumulation.

“This is eruptible material, which is the source of the two episodes of lava flows observed on Sept. 12 and 19,” Phivolcs-Bicol chief volcanologist Ed Laguerta said in a press briefing.

“We are just waiting for the pressure underneath to overcome the pressure exerted by the lava dome and volcano’s edifice, which could trigger a magmatic eruption,” he added.

Laguerta warned that an eruptible transition from a shallow magma chamber to the main magma chamber can also trigger a stronger eruption.

As of yesterday, Mayon’s status was still at Alert Level 3, which means that hazardous eruption is possible within weeks.

No volcanic earthquake was detected in the past 24 hours, while sulfur dioxide emission was measured at an average of 141 tons per day, way below the 500 tons normal output.

The very low sulfur dioxide emission could be due to a low gas content of the magma, according to Ma. Antonia Bornas, chief of Phivolcs Volcano Monitoring and Eruption Prediction Division.

“The situation is very tricky for all of us because if we stand down anytime soon, day to day, the parameters can suddenly change due to the eruptible magma,” Bornas warned.

“So we are closely monitoring the volcano because the parameters can suddenly change. I recalled that the raising of the alert level from 2 to 3 last Sept. 15 took place within a 24-hour period,” she added.

Bornas also said the Phivolcs team delineating the permanent danger zone (PDZ) has put up 48 markers around the restricted area.

The provincial government wants to replace the 200 temporary markers put up by the Provincial Engineering Office with concrete markers as part of the plan to relocate all residents inside the PDZ.