The Keanakakoi eruption was a VEI-4 eruption that occurred from the summit caldera of Kīlauea volcano in or around November 1790. It has been described as the deadliest volcanic eruption in what is now the United States, with more than 400 people having been killed in the event. The eruption deposited the Keanakakoi Ash which surrounds the Kīlauea Caldera.