A pyroclastic flow (also known scientifically as a pyroclastic density current ) is a fast-moving current of superheated gas and rock (collectively known as tephra), which reaches speeds moving away from a volcano of up to 700 km/h (450 mph). A pyroclastic flow from Mayon in the Philippines, seen on September 23, 1984. pyroclastic synonyms, pyroclastic pronunciation, pyroclastic translation, English dictionary definition of pyroclastic. âThe pyroclastic deposits mainly consist of block-and-ash, blast, tephra fallout and secondary pyroclastic flow deposits.â âAnd they also say there's a potential danger from pyroclastic flows.â A pyroclastic flow with a mechanism involving the collapse of an eruption column. Soufriere type. Pyroclastic flows are a very dangerous phenomenon that occur during some volcanic eruptions. A pyroclastic flow with a mechanism that generates nuee ardente deposits of block and ash which are generated by dome collapse caused by a gas driven explosion. Pyroclastic flows are the signature fireworks of the most explosive kinds of volcanic eruptions. Define pyroclastic. St. Helens, Skamania County, Washington August 7, 1980 n. pl. nuée ardente eruption of Mt. Pumice flow. The speed of these flows, as well as the extremely high â¦ âThe pyroclastic deposits mainly consist of block-and-ash, blast, tephra fallout and secondary pyroclastic flow deposits.â âAnd they also say there's a potential danger from pyroclastic flows.â Information and translations of pyroclastic flow in the most comprehensive dictionary definitions resource on the web. Heavy debris falls rapidly from the sky and flows down the flanks of the volcano, mostly as pumice. adj. On the margins of pyroclastic flows, death and serious injury to people and animals may result from burns and inhalation of â¦ In fact, this type of flow is sometimes known as a âpumice flow.â Pyroclastic flow, the fast-moving hot gases, ash, and cinders expelled from a volcano. These mixtures of ash, lava blebs and broiling gas â¦ What does pyroclastic flow mean? Meaning of pyroclastic flow. Composed chiefly of rock fragments or particles of volcanic origin, such as pumice, obsidian, or volcanic ash. A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at velocities of 100 km/h (62 mph) on average but is capable of reaching speeds up to 700 km/h (430 mph). I've labeled the main parts of a pyroclastic, with the leading surge, main body and accompanying ash cloud. Definition of pyroclastic flow in the Definitions.net dictionary. Pyroclastic flows vary considerably in size and speed, but even relatively small flows that move less than 5 km (3 mi) from a volcano can destroy buildings, forests, and farmland. Pyroclastic flow synonyms, Pyroclastic flow pronunciation, Pyroclastic flow translation, English dictionary definition of Pyroclastic flow. Other pyroclastic flows result from the collapse of an eruption column, the vertical mass of debris and gas that jets above an explosive volcano vent.