Lascar is a stratovolcano and the most active volcano of the northern Chilean Andes. The largest eruption of Lascar took place about 26,500 years ago, and following the eruption of the Tumbres scoria flow about 9,000 years ago, activity shifted back to the eastern edifice, where three overlapping craters were formed. Frequent small-to-moderate explosive eruptions have been recorded from Lascar in historical time since the mid-19th century, along with periodic larger eruptions that produced ash and tephra fall up to hundreds of kilometers away from the volcano. The largest eruption of Lascar in recent history took place in 1993, producing pyroclastic flows as far as northwest of the summit and ash fall in Buenos Aires, Argentina, more than to the southeast. The latest series of eruptions began on 18 April 2006 and was continuing as of 2011.