1.Magma from 3,600 cubic miles + 1.5miles deep chamber created a swarm/buldge at crusty surface
1.1 Gas and pressure escaped via Fissure eruption
1.2 Lava dome collapsed as volume decreased, forming a depression called caldera
2. Three (3) Caldera following 2mil, 1.3mil and 0.64mil years old eruptions
3. Eruption would let out 6k more material than 1980 ST Mt Helen
