Active volcanoes in the Philippines, as categorized by the Philippine Institute of Volcanology and Seismology (PHIVOLCS), include volcanoes in the country having erupted within historical times (within the last 600 years), with accounts of these eruptions documented by humans; or having erupted within the last 10,000 years (holocene) based on analyses of datable materials. However, there is no consensus among volcanologists on how to define an active volcano. s of 2012[ [update]], PHIVOLCS lists 23 volcanoes as active in the Philippines, 21 of which have historical eruptions; one, Cabalian, which is a strongly fumarolic volcano; and one, Leonard Kniaseff, which was active 1,800 years ago (C14).