Kawah Ijen is part of the Ijen volcanic complex, which most likely began forming in the late Pleistocene to early Holocene. The exact date of its formation is unknown. (Global Volcano Program, 2024)
Historic Eruptions:
1796: Phreatic eruption.
1817: The crater lake collapse caused a deadly mudflow in villages in Banyuwangi.
1917: Lake overflow and eruptions with boiling water spouting 9 meters high.
1921-1923: Increased lake temperatures and gas emissions.
1936: This eruption caused another mudflow.
1952: Steam eruption and ash rising more than 1,000 meters.
1962: Water color changed, and gas bubbles were seen in the lake.
1993: Explosive eruption.
1997: Strong sulfur smells and birds falling into the lake were observed.
1999: A phreatic eruption with tremors and sulfur floating on the lake was observed.
^(Ijen Plateau, n.d.)