Just to add, there are two main categories of volcanism, shield volcanoes (hot spots, mid ocean ridges) and stratovolcanoes (continental and subduction zone volcanoes). Hawaii is the first kind ("tourist friendly"), Vesuvius at Pompeii is the latter kind (not friendly). The main difference is the silica content, the stratovolcano lava is sticky and viscous; it gets stuck and things get explosive and nasty.

We have a lot of stratovolcanoes around the pacific rim so it's eruptions like those that we should compare with Pompeii, and not really Hawaii.

The two categories also produce, in general, different kinds of rock.