A large eruption, called R1, occurred at the end of the last glacial maximum at Reclus. It was dated by radiocarbon dating to have occurred 12,640 ± 260 radiocarbon years ago. Its total volume has been estimated at over and with a volcanic explosivity index of 6 it is among the largest volcanic eruptions of the Austral Volcanic Zone, exceeding that of Holocene eruptions in the region including the 1991 eruption of Cerro Hudson.