March–June 2006 The
Philippine Institute of Volcanology and Seismology (PHIVOLCS) declared alert level 1 on March 19, after it recorded increased seismic unrest. On June 8, volcanologists raised the alert level to 2 (moderate level of seismic unrest) after the volcano spewed ash. On June 9, the resulting ash cloud damaged a number of houses in the nearby town of
Casiguran, north of the volcano, and reached
Sorsogon City, about north of Bulusan. On June 13, volcanologists said new craters were created by mild explosions. Aside from the new craters, two of the volcano's existing four craters appeared to have merged and cracks were observed on the western rim of the summit crater. Another eruption took place on April 8, 2007.
July–October 2007 Following some signs of volcanic activity, on the morning of July 31, 9:37am (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 , drifting and blanketing the surrounding countryside. The eruption lasted for 20 minutes.
November 2010 On November 7, PHIVOLCS recorded increased seismic activity at Bulusan Volcano, 24 hours after it spewed a ash column and grayish steam on November 5. State volcanologists noted that at least 10 volcanic earthquakes and four explosion-type events were documented after the emission of ash and steam at 8a.m. on November 5. PHIVOLCS also noted that steaming activity was characterized by strong emission of white steam column that reached a maximum height of 200 meters above the crater rim. It warned the public not to enter the four-kilometer permanent danger zone from the volcano. People near the valleys and streams were also advised to be "extra alert" against sediment-laden stream flows in the event of heavy rains. More ash ejection was reported on November 8–9, with ash fall in Juban and Irosin. A PHIVOLCS bulletin on November 9 stated that eight volcanic earthquakes were recorded from the volcano during the past 24 hours and weak to moderate emission of ash explosion was observed. PHIVOLCS also warned residents near valleys and streams against sediment-laden stream flows in the event of heavy and continuous
rainfall.
February 2011 After months of little activity, the volcano suddenly erupted and released a plume of ash high, after water reacted with the hot magma. PHIVOLCS said such explosions were likely to continue for the coming weeks. Initially, hundreds of nearby residents evacuated on their own, but the government stepped in to evacuate thousands more, and imposed a travel ban around the crater. They also advised airplanes to avoid the immediate perimeter due to ash and debris in the air.
May–June 2015 Mount Bulusan ejected a ash plume on May 1, at around 9:46 pm, lasting for 3.5 minutes. The incident was classified as a "minor explosion event" by PHIVOLCS leading to the raising of alert level 1 (abnormal activity) for the surrounding area. A second ash explosion lasting for five minutes also occurred on the same day. PHIVOLCS determined the cause of the eruptions to be hydrothermal activity beneath the volcano. People were advised not to enter the permanent danger zone. Further advisories were given to low-flying aircraft against the dangers of sudden
phreatic eruptions, and to local residents near rivers and streams in case of
lahar flows. There were also concerns that rains from
Typhoon Noul could trigger
lahars and mudslides near the mountain. However, after Noul recurved to the north, the threat did not materialize and the evacuees were permitted to return to their homes. On June 16, Mount Bulusan generated two volcanic eruptions with the first one recorded at 11:02am which lasted for 10 minutes producing a one kilometer high grayish steam and ash plume and accompanied by rumbling sounds. The second one was recorded at 11:20am which lasted for a minute producing only a small ash plume. On June 18, the volcano once again erupted but was not observed visually due to thick clouds covering the summit. Prior to the eruption, rumbling sounds was heard between 5:00am to 7:00am by residents of the village of Monbon in Irosin town. The next day, June 19, Bulusan erupted yet again at around 2:55pm producing a 1.5-kilometer high ash plume.
June 2016 On June 10, almost a year after its last eruption, Mount Bulusan erupted again at 11:35am. The eruption lasted for five minutes and generated an ash plume measuring 6,562 feet or some 2,000 meters. According to
PHIVOLCS, the eruption was phreatic in nature and had a shallow source, with the ash drifting northwest to the direction of
Juban town. While the PHIVOLCS did not raise the alert level 1 in the volcano, it advised residents not to enter the four-kilometer permanent danger zone and warned pilots not to fly near the volcano.
December 2016 On December 29, Mount Bulusan had a phreatic eruption, shooting a plume of ash about two kilometers high. It happened 2:40pm local time and lasted for about 16 minutes. The eruption prompted PHIVOLCS to raise Alert level 1 for the surrounding areas and remind the public not to enter the 4-kilometer radius permanent danger zone.
July 2020 PHIVOLCS raised the alert status of Bulusan Volcano from alert level 0 to alert level 1 after an increase in seismic activity was observed in the past days.
May 2021 On May 11, PHIVOLCS raised the alert status of Bulusan Volcano from alert level 0 to alert level 1 due to increased seismic activity since May 8.
August 2021 On August 18, PHIVOLCS lowered the alert level of Bulusan from alert level 1 (low-level unrest) to alert level 0 (normal) after the volcano returned to normalcy following a general decline in volcanic earthquakes, ground deformation, gas emission, and surface activity.
June 2022 On June 5, PHIVOLCS reported that Mount Bulusan had a phreatic eruption with a height of about one kilometer, and the alert level status was raised to alert level 1. Ash fall was reported in
Juban and
Casiguran. The DOH advised the public to remain indoors. The local government of Juban ordered residents to evacuate from affected areas. The NDRRMC reported at least 180 individuals from Juban were evacuated. On June 12, a phreatic eruption took place at 3:37 am (local time) and lasted for about 18 minutes.
April 2025 At 4:36 am on April 28, Bulusan underwent a
phreatic eruption that lasted 24 minutes and emitted a bent plume that rose 4,500 meters above the crater before drifting to the general west. A
pyroclastic density current (PDC) descended the southwestern slopes, traveling within 3 kilometers from the summit vent of the volcano. The eruption prompted PHIVOLCS to raise Alert Level 1 on the volcano again. Sixty-one people were evacuated from the vicinity. A second phreatic eruption occurred at 7:43 pm on April 29, lasting for 1 hour and 17 minutes and emitting a plume that drifted southwest. ==Monitoring==