A major eruption occurred at Aguilera less than 3,596 ± 230 years before present, it was later constrained to have occurred 3,000 ± 100 years before present, and is known as the A1 eruption of Aguilera. It was a large eruption and deposited tephra east of the volcano and as far south as the Strait of Magellan; other Aguilera tephras are less widespread. Its volume has been estimated to be between , larger than the 1991 eruption of Cerro Hudson, and it is classified as level 5 on the volcanic explosivity index.