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Integrating indigenous myths with new scientific knowledge on late Holocene eruptions of Isarog volcano, Philippines

Timothy John E. Daita 1,2, Christopher J. Harpel3, Sandra G. Catane1, Christopher G. Newhall4, Aljhon Q. Marco1,2

  • Affiliations: 1National Institute of Geological Sciences, University of the Philippines, Diliman, Quezon City, Philippines; 2Department of Science and Technology - Philippine Institute of Volcanology and Seismology (DOST-PHIVOLCS), Diliman, Quezon City, Philippines; 3United States Geological Survey Volcano Disaster Assistance Program (USGS-VDAP), Cascades Volcano Observatory, Vancouver, Washington, USA; 4Mirisbiris Garden and Nature Center,  Salvacion, Sto. Domingo, Albay, Philippines

  • Presentation type: Talk

  • Presentation time: Monday 09:00 - 09:15, Room R380

  • Programme No: 7.1.3

  • Theme 7 > Session 1

Abstract

Prior to its classification as a potentially active volcano and its subsequent reclassification as active based on new ¹⁴C ages in 2013, Isarog volcano in Camarines Sur, Philippines was widely considered extinct from the 19th to mid-20th centuries due to the absence of recorded eruptions. Indigenous communities in the Partido District, however, recount myths that suggest otherwise. The ancient Bicol epic, Ibalón, mentioned an eruption of Isarog and two other volcanoes, accompanied by strong earthquakes. Local legends narrate stories of giant creatures residing in Isarog's crater whose conflicts led to eruptions. Much of the older population also speak of "eruptions of water" rather than magma, possibly indicating ancient crater breaches or lahars. Recent field investigations and ¹⁴C dating of organic material from volcanic deposits revealed that Isarog's most recent eruption occurred sometime during the 12th century. The presence of a potsherd in a paleosol underlying the eruption's deposits suggests human habitation during this period and that people may have witnessed the event, and accounts of other eruptions of Isarog may also be preserved in local myths. Evidence of dome collapses and Plinian eruptions is supported by the presence of block-and-ash flow and tephra-fall deposits. Large boulders inferred to be from lahar deposits are scattered in rice fields 10--15 km downstream from the volcano's crater, providing evidence supporting the myths of catastrophic eruptions of water. Our study emphasizes the value of integrating indigenous knowledge with scientific investigation to uncover overlooked volcanic activity and better understand lesser-known volcanoes and their hazards.