Mayon’s lava dome damaged by ash explosion

LEGAZPI CITY — The lava dome in the crater of Mayon Volcano was damaged by the ash explosion Tuesday morning, the Philippine Institute of Volcanology and Seismology (Phivolcs) said yesterday.

"The configuration of the lava dome has been changed by the phreatic explosion based on our observation from Lignon Hill Observatory," said Ed Laguerta, Phivolcs resident volcanologist, in a telephone interview yesterday.

"But we have to conduct an aerial survey to really determine the exact configuration."

Laguerta has already requested Albay Gov. Fernando Gonzales to provide a helicopter for the aerial survey.

The lava dome has been observed to be slowly building up in the crater of Mayon Volcano before the ash explosion. Faint crater glow can be observed at the summit of the 2,467-meter volcano.

The recorded sulfur gas emission was 1,470 tons per day, which is much larger than the volcano’s normal gas discharge of only 500 tons per day.

Two low frequency volcanic quakes and nine minor explosions were detected in the past 24 hours.

"Due to very thick clouds over the summit, no ash emissions were directly observed although minor ash explosions probably accompanied the seismic events," Phivolcs said.

Laguerta said a team from Phivolcs central office will be arriving here today to assess the extent of the volcano’s inflation, while another team will put up another seismic sensor in the vicinity of Mt. Masarawag. Two seismic sensors are presently being maintained by Phivolcs in Sta. Misericordia and in Barangay Buang.

Last Wednesday, seismic instruments recorded 19 low frequency volcanic quakes, one explosion-type and two high frequency volcanic quakes. Low frequency volcanic quakes are caused by the movement of magma below the summit.

With Mayon’s renewed unrest, Cedric Daep, action officer of the Provincial Disaster Coordinating Council, has issued advisories to the municipal disaster councils in the towns of Camalig, Malilipot, and Daraga, and the cities of Ligao and Tabaco to maintain an alert status.

During an emergency meeting here on Wednesday, Daep said that around 55,000 people could be evacuated from 10 villages located at the slopes of Mayon.

Daep maintains that no human activity will be allowed within the six-kilometer permanent danger zone, especially at the southeast quadrant of the Bonga gully facing this city and Sto. Domingo due to falling rocks and pyroclastic flow. Mountaineers are also warned not to climb the volcano.

Alert level 2, which was hoisted on Oct. 11, 2003, is still being maintained, showing that the volcano is in a period of moderate unrest.

Since its major eruption in July 2001, the volcano has erupted 48 times. The most lethal eruption was in 1814 when it buried the entire town of Cagsawa, killing more than 1,200 people. It’s eruption in 1993 killed 78 farmers. — With Felix delos Santos