pyroclastic flow

treeseed commented on the word pyroclastic flow

A pyroclastic flow (also known as a pyroclastic density current) is a common and devastating result of some volcanic eruptions. The flows are fast-moving currents of hot gas, and rock (collectively known as tefra), which travel away from the volcano at speeds generally greater than 80 km/hr (50mph).1 The gas can reach temperatures of up to 1,000 degrees Celsius (1,832 F). The flows normally hug the ground and travel downhill, or spread laterally under gravity. Their speed depends upon the density of the current, the volcanic output rate, and the gradient of the slope. The word pyroclast is derived from the Greek πυ�?ος, meaning fire, and κλαστός, meaning broken.

_Wikipedia

February 5, 2008

artoparts commented on the word pyroclastic flow

See: nuée ardente.

March 24, 2009

MaryW commented on the word pyroclastic flow

Sometimes, a superhot avalanche of rock, ash, and steam races down the volcano's sides in what scientists call a pyroclastic flow, with speeds up to 300 miles per hour. With the volcano's vent once again opened by the blast, thick lava flows are able to pour more peacefully out of the crater decades, centuries, or millennia later.

The scientists were also worried about the possibility of a pyroclastic flow—an absolute death sentence that kills not from the heat but from inhalation of scalding hot ash. On the first breath, a person's lungs react with instant pneumonia and fill with fluid. With the second breath, the fluid and ash mix and create wet cement. By the time the person takes a third breath, thick, hot cement fills the lungs and windpipe, causing the victim to suffocate.

May 1, 2016