LEGAZPI CITY, July 10 -- Mayon volcano has manifested increasing volcanic quakes, swelling of its edifice and intense crater glow, prompting the Philippine Institute of Volcanology and Seismology (Phivolcs) to raise the volcano's alert status to Level 2.
Phivolcs said the raising of the alert status of the volcano from Level 1 to 2 was based on the aerial and ground leveling surveys conducted by the agency.
This means that the volcano's alert condition signifies a state of unrest which could lead to ash explosions or eventually to hazardous magmatic eruption, the agency added.
The surveys showed that there was indeed a surge in the volcano's seismic activity manifested by the number of low- frequency volcanic earthquakes rising to a higher level, signifying possible movement of magma beneath the volcano edifice.
Ground deformation was also noted with a ground uplift of about one centimeter as measured by Precise Leveling Survey conducted last June 15-22, and the inflation was sustained during a resurvey on Thursday.
Ed Laguerta, Phivolcs resident volcanologist, said aerial survey on Wednesday showed a cone-shaped pile of hot, steaming old rocks, possibly remnants from previous eruptions which could be the source of the glow at the crater.
Laguerta explained that the low-frequency volcanic quakes and ground deformation could indicate that fresh volcanic materials are moving upward, causing the formation of the cone-shaped pile of materials at the crater.
As this developed, Albay Gov. Joey Salceda directed the Albay Public Safety and Emergency Management Office (APSEMO) to start updating the population at risk and critical resources data of cities and towns around the volcano.
This data would be the basis for determining the number of people to be placed in safer grounds when Mayon volcano condition goes on eruptive stage.
Based on APSEMO's data, population at risk in time of eruption at the six-kilometer Permanent Danger Zone (PDZ) are in the cities of Tabaco, four villages, and Ligao, two villages; and the towns of Malilipot with three villages; Camalig, three villages; Guinobatan and Daraga, one village each.
Based on previous studies, population at risk in these areas (6-km PDZ) is estimated at 1,675 families or 6,996 people.
Villages at risk in the 6.5-km to 8.5-km extended danger zone are four villages in Daraga; five villages in Camalig; two villages in Guinobatan; three villages in Ligao City; five villages in Tabaco City, and two villages in Malilipot, affecting an estimated 6,700 families or 37,000 people.
Villages at risk in the southeastern quadrant of the volcano located at the 8- to 10-km Danger Zone are 12 villages in this city and nine villages in Sto. Domingo town, the data indicated. Population in these areas are at risk from pyroclastic flows and mudflows in times of heavy rains.
Salceda also directed city and town disaster councils around the volcano to be on 24-hour watch and to review their respective contingency plans and evaluate their communications and warning capacities. (PNA)