GEOLOGY

Detailed explanation-1: -A pyroclastic flow is a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases. It occurs as part of certain volcanic eruptions. A pyroclastic flow is extremely hot, burning anything in its path. It may move at speeds as high as 200 m/s.

Detailed explanation-2: -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-3: -Composite volcanoes, sometimes known as strato volcanoes, are steep sided cones formed from layers of ash and [lava] flows. The eruptions from these volcanoes may be a pyroclastic flow rather than a flow of lava. A pyroclastic flow is a superheated mixture of hot steam, ash, rock and dust.

Detailed explanation-4: -Composite volcanoes are tall, symetrically shaped, with steep sides, sometimes rising 10, 000 feet high. They are built of alternating layers of lava flows, volcanic ash, and cinders.