Bulusan volcano remains quiet

LEGAZPI CITY — Bulusan volcano remained quiet after it spit out ash Wednesday. Seismic monitors around the volcano recorded not a single volcanic quake during the past 24 hours.

However, wispy to moderate steam continue to emit from the active summit vents and fissures located in the western sector. According to the Philippine Institute of Volcanology and Seismology (Phivolcs), alert level 2 is still hoisted over the area.

"If ash explosions should occur, these are likely to directly affect the summit area and upper slopes only," Phivolcs said.

The agency observed no volcanic earthquake from 8 a.m. last Sunday until 8 a.m. yesterday. Steam explosion was generally weak and sometimes moderate at the active summit craters, including the western fissure.

Sulfur gas emission was placed at about 161 tons per day, which is way below the normal level of about 600 tons per day.

"The sulfur dioxide flux of the volcanic plume, measured at 161 tons per day is considered low," said Phivolcs.

It added that no new lava explosions were observed in the volcano "which means that a magmatic eruption is not imminent."

Phivolcs warned though that at this time of year, the northeastern and northern sectors of the volcano might experience ashfalls carried by prevailing wind.

The four-kilometer danger zone remains prohibited to the public while areas beyond this point should be approached with caution because these places could be affected by volcanic flow in case of a large explosion.

The public was also told to avoid gullies which lead to the middle and upper slopes because hazardous lahar might be channeled to areas beyond the danger zone, especially during the rainy season.

Aerial survey conducted yesterday morning showed that Bulusan has four existing craters.

The summit crater of the 1,600-meter volcano showed reactivated craters from four old craters.

Ed Laguerta, the Phivolcs scientist who supervised the aerial survey, said the current explosion site was at the central part of the summit.

Bulusan emitted ash anew Wednesday night, the explosion reaching about two kilometers from the summit and drifting towards the north and northwest direction. It left about four millimeters of ash in Barangay Inlagadian in Casiguran town and other villages in Juban town.

"We did not discover any extruded lava at the surface," said Laguerta who was on board a Huey helicopter during the aerial survey. He added that all explosion deposits are pyroclastic materials such as ash, boulders, and pebbles lying on the slopes of the volcano.

Laguerta assures the thousands of residents in the towns of Barcelona, Bulusan, Irosing and Juban that there is "no eminent danger of changing from phreatic activity to a magmatic one which is more dangerous in terms of hazards to the barangays located at the foot of the volcano, especially those outside the four-kilometer permanent danger zone."

He explained that if there will be another activity, it will be just another ash explosion.

"Change in the character (of Mt. Bulusan) will be reflected in the type of earthquakes that will be recorded and the volume of the sulfur dioxide emitted by the volcano."

Earlier, Crispolo Diolata Jr., officer-in-charge of Bulusan Volcano monitoring station, said that the phreatic explosion on Wednesday created more cracks or fissures on the volcano’s slopes. — With Cet Dematera