But how did Mt Katmai come to be demolished? 
It's thought that at the  time of the eruption a large volume of molten rock may have existed in a  magma chamber beneath the volcano, and that this was connected by some  kind of subterranean volcanic plumbing with the vents around Novarupta,  eight kilometres away, so that most of the material that was actually  erupted at these vents was <tag "515674">derived</> from beneath Katmai.   

