Paradise Philippines: Bulusan Volcano Ashes
Mt. Bulusan or Volcano Bulusan Located: Sorsogon Province, 70 km southeast of Mayon Volcano and approximately 250km SE of Manila (12°46.2′N, 124°03′E)
Phivolcs raises alert of Bulusan volcano State volcanologists raised the alert level 1 to 2 at the volatile Bulusan volcano effective this July 30, warning about the possibility of an explosive eruption.Over the past three days, 673 earthquakes have been recorded in the area of the volcano, up from 223 tremors during the previous three-day period, Philippine Institute of Volcanology and Seismology (Phivolcs) Director Renato Solidum Jr. said.
Experts have warned that a major eruption could threaten the lives of at least 20,000 people in a “worst-case scenario.”
Bulusan is one of the most active of the 22 volcanoes that have erupted within recorded history in the Philippines. It has erupted 15 times, most recently in November 1994.
PHYSICAL CHARACTERISTICS:
Height: 1.559 m above sea level (asl)
Base Area: 400 km²
Craters: Four (4) craters aligned along N 70° W
Crater #1 - Blackbird Lake, 20 m diameter; 15 m deep
Crater #2 - Oval in shape; 60 m by 30 m; 15 m deep
Crater #3 - 90 m diameter; 20 m deep
Crater #4 - NW tip of the volcano; 60 m by 30 m by 20 m
Type of Volcano: Stratovolcano formed inside a caldera
Predominant Rock: Two pyroxene andesite in Bulusan, dacite associated with caldera
Irosin Caldera: 200 m depth; 11 km dia.; age greater than 40,000 years
(C-14 dating&method)
Cones: Mt. Homahan, Mt. Binicatan, Mt. Batuan, Mt. Calungalan,
Mt. Calaunan, Mt. Tabon-Tabon, Mt. Juban, Mt. Jormajan
Lakes: Bulusan Lake - SE at elevation 635 m asl; 33 m deep; 16.5 hectares (area);
2 km circumference, formed by damming of a river by lava flows
Lake Aguingay - Between the trough of Mt. Bulusan and Sharp Peak; 1100 m asl
HISTORICAL ERUPTIONS:
No. of Recorded Eruptions: 18 eruptions since 1852
Destructive Eruption: Calderagenic eruption which occured 40,000 years before present (YBP)
Latest Eruption: 27 November 1994
Type of Eruptions: Phreatic - explosion driven by steam produced by heat and expansion of ground water
due to an underlying hot source (e.g. 1918-1922, 1980 eruptions) Strombolian - quiet effusion of lava
(1918-1919 eruptions) Caldear-forming eruption (40,000 YBP)
Eruption Precursors: Increase in frequency of quakes with rumbling sounds Increased steaming activity
Noticeable increase in the extent of drying up of vegetation around the volcano’s uppper slopes
Phenomena Associated with Eruption: Lava flows, Pyroclastic flows, Lahars
