Mount Bulusan

Mount Bulusan
Mount Bulusan | (National Museum Bicol (@nmbicol)

Mount Bulusan: A volcano with four craters and three lakes.

As we continue our Bulkan Ng Bikol series, let’s proceed to the southern tip of the Bicol peninsula for a quick stopover at one of the active volcanoes in the country with the most recent eruption.

On top of our list is a young stratovolcano named Bulusan covering an area of ~900 sq. km. Bulusan Volcano is shared by Casiguran, Barcelona, Irosin, and Juban in the Sorsogon province.

Mt Bulusan is the country’s fourth active volcano. It recently spewed ash and steam during a phreatic eruption last 2022 June 5, prompting the Philippine Institute of Volcanology and Seismology (PHIVOLCS) to raise Bulusan Volcano’s alert level status from 0 to 1, which means that it is currently at low-level unrest.

Its last known eruption was recorded last 12 June 2022, and explosive activity with ash ejection occurred in 2006-2007, 2010, and 2011. Many moderate explosive eruptions have also been recorded since the mid-19th century. Heavy rains often trigger mudflows from loose deposits on the flank.

Bulusan volcano lies in the so-called Bulusan Volcanic Complex (BVC), along with the 11-km wide Irosin caldera and older dissected volcanic centers that include the Gate Mountains at the southern tip of the peninsula and Mt. Bintacan to the west. Bulusan is an andesitic volcano built upon the northeast rim of the older Irosin Caldera, formed about 41,000 years ago during the post-caldera stage. Rising to 1,565 meters above the low-lying floor of Irosin Caldera, Bulusan Volcano is the youngest of several cones and lava domes within the caldera. The rocks found in Bulusan Volcano vary from basalt to dacite but are dominated by andesites.

Its summit is unvegetated and contains a 300-m wide, 50-m-deep crater, along with several vents and fissures. Three other small craters are located on Bulusan’s southeast flank. Within Bulusan also lies three lakes, namely—Bulusan Lake, which is found at the foot of the volcano; Lake Aguingay, which is located in the middle of the volcano; and Blackbirds’ Lake, which is near the summit of the volcano,

Photo: Jarod Maggio

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