How does an explosive eruption produce pyroclastic flow?

The other type of pyroclastic flow is caused by the collapse of a lava dome, the swelling of the earth caused by pressure from magma below. This pyroclastic flow actually has two major components, the visible ash cloud along with an avalanche of hot blocks from the disintegrating dome. The two types of flows leave different types of ash deposits, which geologists can identify long after an eruption.

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.

i think the answer is tomato juice? not entirely sure though