According to the Volcanic Explosivity Index , a VEI of 6 to 8 is classified as " ultra-Plinian " . Eruptions of this type are defined by ash plumes over high and a volume of erupted material to in size . Eruptions in the ultra-Plinian category include the Lava Creek eruption of the Yellowstone Caldera ( approx 640,000 years ago , VEI 8 ) , Lake Toba ( approx 74000 years ago , VEI 8 ) , Tambora ( 1815 , VEI 7 ) , Krakatoa ( 1883 , VEI 6 ) , Akahoya eruption of Kikai Caldera , Japan , and the 1991 Mount Pinatubo eruption in the Philippines ( VEI 6 )
Tambora
1815 eruption of Mount Tambora
Plinian eruption