Increased activity at Bulusan volcano, Philippines

bulusan volcano september 21 2022 f

Activity under Bulusan volcano, Philippines increased on October 6, 2022. While the volcano is still on Alert Level 0 (Normal), this is subject to change should current activity persist.

  • There are increased chances of steam-driven or phreatic eruptions
  • Entry into the 4 km (2.5 miles) radius danger zone is prohibited
  • People living near the volcano should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall.

The Bulusan Volcano Network recorded a total of 29 volcanic earthquakes between 05:00 LT on October 6 and 15:00 LT on October 7, 2022.

In addition, ground deformation data from continuous GPS measurements and radial tilt indicate short-term inflation of the general southern edifice of Bulusan volcano since April 2022.

Furthermore, 279 tonnes per day of sulfur dioxide (SO2) emission was measured on September 29, 2022.

Weak to moderate emission of white steam-laden plumes could be observed at the crater while very weak emission of the white-steam laden plumes could be observed at northwest vents.

The increased seismic activity and short-term ground deformation are likely caused by shallow hydrothermal processes beneath the edifice, PHIVOLCS reports.1

Bulusan volcano on September 21, 2022
Bulusan volcano on September 21, 2022. Credit: Copernicus EU/Sentinel-2, EO Browser, The Watchers

Since hydrothermal processes are underway beneath the volcano, there are increased chances of steam-driven or phreatic eruptions from its active vents.

Local government units and the public are reminded that entry into the 4 km (2.5 miles) radius Permanent Danger Zone (PDZ) should be prohibited.

People living within valleys and along river/stream channels, especially on the southeast, southwest and northwest sector of the edifice should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall.

A powerful phreatic eruption took place at the volcano at 02:37 UTC (10:37 LT) on June 5, 2022:

Another powerful eruption took place on June 12, covering nearby communities in heavy ash:

Geological summary

Luzon’s southernmost volcano, Bulusan, was constructed along the rim of the 11-km-diameter (6.8 miles) dacitic-to-rhyolitic Irosin caldera, which was formed about 36 000 years ago.

Bulusan lies at the SE end of the Bicol volcanic arc occupying the peninsula of the same name that forms the elongated SE tip of Luzon. A broad, flat moat is located below the topographically prominent SW rim of Irosin caldera; the NE rim is buried by the andesitic Bulusan complex.

Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE.

The summit of 1 565-m-high (5 134  feet) Bulusan volcano is unvegetated and contains a 300-m-wide (984 feet), 50-m-deep (164 feet) crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded at Bulusan since the mid-19th century.2



2 Bulusan – Geological summary – GVP

Featured image credit: PDERG


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