Following some signs of volcanic activity, on the morning of July 31, 2007, 9:37 am (local time), there was a loud explosion described by locals as "like a bomb going off".
A cloud of steam and ash shot into the air from Mount Bulusan to a height of 5 kilometers (3.1 mi), drifted and deposited over the surrounding countryside.
The eruption lasted for 20 minutes.

On October 4, 2007, two episodes of ash explosions occurred as recorded by the seismic network.
The explosions were not visually observed due to thick clouds covering the volcano's summit.
The events were recorded as explosion type-earthquakes at 1:34 am and 1:39 am.
The seismic network recorded 40 volcanic earthquakes and 8 short duration harmonic tremors during the previous 24 hours.
Ground deformation surveys along the Inlagadian leveling line at the northeast flank indicated a slight inflation of the volcano's edifice.
Field investigation conducted showed trace to light ashfalls affecting barangays San Roque, San Rafael, Sitio Tawog of Porog, Porog proper and Bulusan town proper, all in the municipality of Bulusan.

The October 2007 ash explosions at Bulusan Volcano were preceded by sporadic swarms of small to moderate-sized amplitude earthquakes, which began occurring in the last week of September 2007.
Evacuations took place during the July–August episodes of activity.
Following some signs of volcanic activity, on the morning of July 31, 2007, 9:37 am (local time), there was a loud explosion described by locals as "like a bomb going off". A cloud of steam and ash shot into the air from Mount Bulusan to a height of 5 kilometers (3.1 mi), drifted and deposited over the surrounding countryside. The eruption lasted for 20 minutes.
On October 4, 2007, two episodes of ash explosions occurred as recorded by the seismic network. The explosions were not visually observed due to thick clouds covering the volcano's summit. The events were recorded as explosion type-earthquakes at 1:34 am and 1:39 am. The seismic network recorded 40 volcanic earthquakes and 8 short duration harmonic tremors during the previous 24 hours. Ground deformation surveys along the Inlagadian leveling line at the northeast flank indicated a slight inflation of the volcano's edifice. Field investigation conducted showed trace to light ashfalls affecting barangays San Roque, San Rafael, Sitio Tawog of Porog, Porog proper and Bulusan town proper, all in the municipality of Bulusan.
The October 2007 ash explosions at Bulusan Volcano were preceded by sporadic swarms of small to moderate-sized amplitude earthquakes, which began occurring in the last week of September 2007. Evacuations took place during the July–August episodes of activity.
Mount Bulusan