Dr. Ernesto Corpus, chief of the volcano monitoring division of the Philippine Institute of Volcanology and Seismology (Phivolcs), said it is high time for everybody to refer to Mayon’s eruption characteristics as "mayonian" because these traits are so unique that only this Philippine volcano has continuously displayed them in most of its 46 eruption episodes since the 15th century.
He said the term "strombolian," which is characterized by ash ejections and lava fountaining, derived its name from Stromboli volcano in Italy, while the term "vulcanian," characterized by strong explosions, lava flow and pyroclastic flow, derived its name from the Vulcano volcano in Sicily.
"We know that Mayon, since its recorded history in 1616, had been displaying eruption characteristics that are either a combination of strombolian and vulcanian or of distinct types. Therefore it is easier to describe Mayon’s type of eruption as mayonian," Corpus told The STAR yesterday.
He said the term "taalian" to refer to the eruption characteristics of Taal volcano in Batangas is now gaining ground in the volcanology community. This refers to eruption episodes dominated by water explosions and mud-geysering.
Corpus admitted they are running out of available names whenever they are asked to describe Mayon’s abnormal eruption episodes, saying the volcano with the near-perfect cone has its own unique patterns of abnormal behavior.
"We believe that it would be a lot easier if we would just refer (to it as) or call it mayonian. The existing terms such as strombolian and vulcanian will just be used as points of reference or comparison," he added.
Corpus said the very prolonged lava extrusion neither fall singly in either strombolian or vulcanian types and the shift in Mayon’s eruption episodes do not always follow the known two eruption patterns.
He also said the gaps between Mayon’s recorded eruptions are also very unpredictable, adding that during its earlier explosions the gaps ranged from 10 to 150 years, as compared to the recent gap range of one year to 10 years.
Based on its 46 recorded eruptions, Mayon first blew its top in 1616, then followed by another in 1766, or after 150 years of slumber. After erupting again in 1800 and 1811, the 2,462-meter volcano saw its worst explosion on Feb. 1, 1814, so strong that lava and other volcanic materials buried the entire village of Cagsawa in the old Daraga town in Albay and its church, killing at least 1,200 villagers.
Its eruption episodes in 1827, 1834, 1839, 1845, 1846, 1851, 1853, 1855, 1858, 1861, 1862, and 1868 followed either the strombolian or vulcanian pattern. It later erupted in three consecutive years in 1871 to 1873, and exploded at least five times more from 1876 to 1888.
Again, Mayon erupted in six consecutive years, from 1890 to 1893, paused for one year, then exploded for three more years from 1895 to 1897. Records showed that the 1897 eruption was the second worst, characterized by "very high ash clouds, pyroclastic flows and thunderous rumblings." From 1897 to 2001, Mayon exploded 14 more times, the strongest of which were in 1968 and 1984, the latter causing the collapse of the Bonga gully, the biggest scar on the slopes of the volcano. — With Sheila Crisostomo