How long do volcanoes erupt for?According to the catalog “Volcanoes of the World” by Smithsonian Institution volcanologists Tom Simkin and Lee Siebert, 9 percent of eruptions end in less than one day, 16 percent within two days, 24 percent within one week, 30 percent within two weeks, 43 percent within a month, 53 percent within two months, 83