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
It is not a composite volcano or a cinder cone volcano... it's not even a shield volcano so it is NOT one of the three main volcanoes
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.