The sunken volcanic cinder cone of Molokini Crater was formed as the land mass of Maui moved over hot spots in the Earth’s tectonic plates. At this time, the volcanic eruptions occurred in many spots on the southwest side of Maui.
Though previously thought to have erupted in the last 50,000 years, more recent studies find that it was more likely an older eruption that created Molokini Crater some 230,000 years ago. A graduate student at Kyoto University in Japan, Yoshitomo Nishimitsu, along with scientists at the Hawaiian Volcano Observatory concluded through potassium-argon dating that it indeed erupted at the earlier date. Molokini likely erupted along with other relatively concurrent eruptions along Haleakala’s southwest rift zone.