Timeline of Bulusan Volcano's activity

2006

March 19, 2006: PHIVOLCS raised Alert Level 1 on Bulusan Volcano after recording higher than usual seismic activity, including several imperceptible volcanic earthquakes and steam emission from the summit area.

March 21, 2006: Bulusan Volcano produced an ash explosion from its summit crater.

April 29, 2006: An ash explosion occurred at Bulusan Volcano, producing a light gray ash column that rose to about 1.5 km above the summit. Residents near the foothills west of the volcano also heard a faint rumbling sound.

May 25, 2006: An ash explosion occurred but it was not visible because the summit was cloud-covered.

May 31, 2006: Bulusan Volcano produced a mild ash explosion.

June 7, 2006: Bulusan Volcano spewed ash. Increasing volcanic activity and the likely involvement of magma as the cause of recent explosions prompted PHIVOLCS to raise the alert status of Bulusan Volcano from Alert Level 1 to Alert Level 2.

June 10, 2006: An ash explosion occurred from the summit crater. The explosion produced an ash and steam cloud which rose to about 1 km above the volcano's summit.

June 13, 2006: Bulusan volcano exploded. The explosion produced an ash and steam cloud, which rose to about 1.5 kms above the volcano's summit. Heavy ashfall (at least 7 mm thick) affected Barangays Aroroy, Mabini and Añog while ashfall up to 1 mm thick affected Barangay Bacolod and south of Poblacion of Juban. Traces of ash deposits were noted in Barangay San Juan of Casiguran. The ash explosion was recorded for about 13 minutes.

Small volcanic quakes followed the explosion.

The explosion and relatively voluminous ash emission indicated that Bulusan Volcano is undergoing a period of elevated unrest, distinct from the early explosions from March to May.

June 18, 2006: An ash explosion occurred from the summit crater of Bulusan Volcano. The explosion produced ash and steam columns, which rose up to 1.5 kilometers above the summit.

PHIVOLCS noted that although the recent explosions lasted somewhat longer than earlier ash ejections. However, it remains to be seen if the recent explosions would induce a major hazardous eruption because the very low earthquake activity suggested otherwise.

June 19, 2006: Bulusan Volcano lapsed into apparent quiet. No earthquake was detected and steam emission diminished to weak levels.

June 20, 2006: A mild ash explosion occurred from the summit crater. The ash and steam emission coincided with heavy rains that generated some lahars and torrential flows. Alert level 2 remained in effect.

June 28, 2006: Clouds obscured an explosion at Bulusan Volcano.

July 29, 2006: The alert status of Bulusan Volcano was lowered to Alert Level 1.

October 20 and 23, 2006: Bulusan Volcano ejected ash.

October 30-31, 2006: Ash explosions occurred at the volcano.

November 22, 2006: Small swarms of volcanic earthquakes began. The number of earthquakes increased in the following days.

December 20, 2006: An ash explosion occurred at Bulusan Volcano, although the actual explosion was not observed due to thick clouds covering the summit. The activity was accompanied by rumbling sounds and lightning flashes.

2007

January 24, 2007: An ash explosion occurred at Bulusan Volcano.

January 26, 2007: Another ash explosion occurred from Bulusan Volcano's summit crater. PHIVOLCS noted that the explosion may signal another episode of eruptions similar to the volcanic activity which took place between March and October 2006.

Bulusan Volcano continued to emit dirty white steam clouds in the following days.

April 7 and 17, 2007: PHIVOLCS noted signs of increased volcanic activity at Bulusan Volcano, recording a significant rise in the number of volcanic earthquakes in the past few days.

April 8-9, 2007: Ash explosions occurred at Bulusan Volcano but were obscured from view by thick rain clouds.

May 12, 2007: An ash explosion occurred at Bulusan Volcano, generating a 4-km high eruption column.

May 20, 2007: PHIVOLCS raised the alert status of Bulusan Volcano to Alert Level 2 after noting a high level of seismic activity which continued to increase after the May 12 ash explosion.

July 13, 2007: PHIVOLCS lowered the alert status of Bulusan to Alert Level 1.

July 31, 2007: An ash explosion occurred at Bulusan Volcano, generating a 5-km. high eruption column.

Source: PHIVOLCS