Thursday, August 03, 2006

Mt. Mayon makes the ground move 51 times!

Low-frequency quakes rocked Mt. Mayon even as its steam emission dropped suddenly, indicating an explosive eruption is highly possible, scientists said yesterday.

The Philippine Institute of Volcanology and Seismology said the low-steam emission indicated gas was being blocked by fresh magma and building pressure in the volcano’s vents.

Seismic instruments detected 51 low-frequency quakes compared with the 16 recorded on Wednesday, indicating the volcano was bringing more magma up to the crater, it said.

The instruments also recorded 343 tremors caused by lava tumbling down the volcano’s slopes.
“The presence of low-frequency volcanic earthquakes triggered by the active degassing and partial blockade of viscous magma would lead to either a continuing lava flow or an explosive eruption,” volcanologist Ed Laguerta said.

Scientists said the sudden drop in the volcano’s sulfur dioxide emission did not mean Mt. Mayon had stopped degassing.

The volcano disgorged 4,760 tons of sulfur dioxide yesterday compared with 12,548 tons on Wednesday, but that only meant magma was partially blocking the gas’ path, Laguerta said.
The partial blockade also meant the volcano was building up pressure that could lead to an explosion, he said.

The volume of lava emitted since Mayon started its “mild” eruptions on July 14 had reached 18 million cubic meters, and most of it had flowed down the Mabinit Channel south-southeast of the crater.

Subsequent flows filled the gullies at the southeast’s upper and middle slopes, from Miisi Channel in Daraga to Buyoan Channel in this city.

The lava front is now as big as a four-story building, and it is nearing the 6-km permanent-danger zone after incinerating hectares of coconut plantation and farmland in Mabinit town.

The town’s farmers have cut hundreds of coconut trees so they can use them before lava destroys them.

Officials said Alert Level 3 was still up, meaning sudden explosions and lava avalanches could happen any time.

The danger zones remained off-limits to all residents and visitors.

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