Semeru's eruptive history is extensive. Since 1818, at least 55 eruptions have been recorded (10 of which resulted in fatalities) consisting of both lava flows and pyroclastic flows. All historical eruptions have had a Volcanic Explosivity Index (VEI) of 2 or 3. Semeru has been in a state of near-constant eruption from 1967 to the present. At times, small eruptions happen every 20 minutes or so.