GEOLOGY

Detailed explanation-1: -Pyroclastic flows contain a high-density mix of hot lava blocks, pumice, ash and volcanic gas. They move at very high speed down volcanic slopes, typically following valleys.

Detailed explanation-2: -There are two types of pyroclastic density currents: pyroclastic flows and pyroclastic surges. Pyroclastic flows are high-density currents of pumice, ash, blocks, and volcanic gas that rapidly move down the slopes of a volcano.

Detailed explanation-3: -Pumice is pyroclastic igneous rock that was almost completely liquid at the moment of effusion and was so rapidly cooled that there was no time for it to crystallize. When it solidified, the vapours dissolved in it were suddenly released, the whole mass swelling up into a froth that immediately consolidated.

Detailed explanation-4: -A pyroclastic flow is a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases.