You searched for: “pyroclasm”
pyroclasm
1. Composed chiefly of rock fragments of volcanic origin.
2. A churning cauldron or a pyroclastic flow.

There's an explosive arc, reminiscent of the way a solar flare arcs up and then collapses with a splash.

This entry is located in the following units: clast-, clas-, -clastic, -clast, -clase, -clasia, -clasis, -clasis, -clasmic, -clasm (page 5) pyro-, pyr- (page 1)