In 2018, Klauea Volcano experienced its largest lower East Rift Zone *(LERZ) eruption and caldera collapse in at least 200 years. After collapse of the Pu'u 'O' O vent on 30 April, magma propagated downrift. Eruptive fissures opened in the LERZ on 3 May, eventually extending -6.8 kilometers. A 4 May earthquake [moment magnitude *(Mw) 6.9] produced -5 meters of fault slip. Lava erupted at rates exceeding 100 cubic meters per second, eventually covering 35.5 square kilometers. The summit magma system partially drained, producing minor explosions and near-daily collapses releasing energy equivalent to Mw 4.7 to 5.4 earthquakes. Activity declined rapidly on 4 August. Summit collapse and lava flow volume estimates are roughly equivalent-about 0.8 cubic kilometers. Careful historical observation and monitoring of Kilauea enabled successful forecasting of hazardous events.