Very. The reports of the blast in which Kraktoa was destroyed are almost beyond belief. And there were larger volcanic blasts in the distant past. Krakatoa was a 6 on the Volcanic Explosivity Index while Tambora was a 7. Need links? You got 'em.
Mount Pinatubo is violent.
violent and very active what volcano is not violent
Cinder cone volcano
That would be an extinct volcano.
If it erupts
yes
Mount St Helens is violent.
strato volcano
Stratovolcano (a composite volcano)
Cinder cone volcano
During the more violent eruptions, pieces of the rim of the volcano can break away, changing the shape of the volcano.
Magma that hardens in a vent on an active volcano. They trap gasses in the volcano and can sometimes cause violent eruptions.