THE Civil Aviation Authority of the Philippines on Monday issued a notice to airmen advising them to avoid flying near Mount Bulusan in Sorsogon, which according to the weather bureau, is in abnormal condition and period of unrest.
“Notice to Airmen B3851/16 effective 9:00 am today until 9:00 am Tuesday (Oct. 18) after Mount Bulusan in Sorsogon spewed volcanic ash over 1 kilometer high this morning,” the CAAP stated in its advisory.
The agency issued the warning after the Philippine Institute of Volcanology and Seismology reported that phreatic explosions occurred over the volcano that remains on alert number 1.
CAAP also advised the pilots flying near the area to exercise extreme caution when passing between Lopez and Masbate airspace.
Volcanic eruption and ash clouds could have significant impacts on aircraft operations, according to CAAP.
Notam is a notice distributed by means of telecommunication containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operations.
The weather bureau stated that steam explosion produced a 1 to 1.5-kilometer-high ash plume above the summit and drifted toward the southwest.
The volcano sent a kilometer-high white grayish cloud into the air that lasted for 24 minutes Monday morning, its second this month, Phivolcs said.
“Though the event was a minor phreatic eruption that is produced by steam the volcano’s restiveness has remained,” said Eduardo Laguerta, Phivolcs’ resident volcanologist.
Bulusan volcano’s eruption on Monday is the second this month after the first on Oct. 6 but it is the 20th eruption since May last year, he said.
Phivolcs’ monitoring instruments recorded 24 volcanic earthquakes during the past 24-hour period, its 8 a.m. bulletin said.
Laguerta said the earthquakes were triggered by rock fracturing due to the hydrothermal pressure that has developed in the volcano’s vent which also generates the phreatic or steam-driven explosion.
Aside from the quakes that shook the volcano it also emitted 79 tons of sulfur dioxide which Laguerta said was of “normal value.”
Alert Level 1 (abnormal), which was hoisted over Bulusan volcano in September to denote its restiveness, remains in effect.
The public are reminded not to enter the designated four-kilometer Permanent Danger Zone due to the possibility of sudden and hazardous phreatic eruptions.
Civil aviation authorities advised pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption could be hazardous to aircrafts.
Residents near river channels, especially on the southwest and northwest sectors of the volcano’s slopes should be cautious against lahar flows in the event of heavy rains and prolonged rainfall, added Phivolcs.