MANILA, Philippines - Two days before Christmas, Bulusan Volcano in Sorsogon province spewed a 500-meter ash column, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported.

The Phivolcs said the ash explosion occurred around 9:16 a.m. Thursday (December 23).

It added that 6 volcanic earthquakes were recorded during the past 24 hours.

Bulusan volcano's last recorded ash explosion was last December 16. The Phivolcs said the volcano spewed a 500-meter ash column and it lasted for 3 minutes.

The Phivolcs said it has started a "FLYSPEC" monitoring to determine the quantity of volcanic sulfur dioxide spewed out by the volcano.

The Phivolcs said Alert Level 1 remained up over the volcano and residents should continue to avoid areas within the 4-kilometer radius permanent danger zone. -- Report from Jose Carretero, ABS-CBN Bicol