Pyroclastic materials are individual fragments of magma and rock that are created by explosions during volcanic eruptions. When unconsolidated, these fragments are called tephra. When they group together and form consolidated rocks, they are called pyroclastic rocks.Know More
Tephra fall into three classes, based on the grain of the pyroclastic fragments. The smallest fragments of 2 mm or less are considered ash; those between 2 mm and 64 mm are lapilli; and those greater than 64 mm are called blocks or bombs. Finer distinctions between tephra types are made based on the physical attributes of the fragments.
Pyroclastic rocks are classified based on their general composition. Ash tuff and lapilli tuff consist primarily of ash and lapilli, respectively. Tuff and pyroclastic breccia include blocks and bombs, and are differentiated by the proportion of these compared to the amount of ash and lapilli. Finally, agglomerate and agglutinate have more consistent chunks of rock, with agglutinate being primarily single large chunks of tephra.Learn more in Volcanoes
Pyroclastic material is the mixture of hot rock, ash and lava fragments that are thrown from the vent of a volcano during an eruption. Pyroclastic material typically moves away from the vent at a rapid rate of speed carried along by hot gases.Full Answer >
Quiet eruptions are volcanic eruptions that explode gently, with broad sheets of slowly flowing lava. Shield volcanoes, such as those in Hawaii, are commonly associated with quiet eruptions.Full Answer >
Mudflow on a volcano is called lahar and is typically caused by heavy rains during or after volcanic eruptions. Lahars can also occur when nearby ice or snow melts, carrying ash and rock debris down a volcano's slopes.Full Answer >
Volcanic vents allow the Earth to release built up gases from the heat and pressure emanating from its core. Magma rises towards the surface, and as the pressure builds the magma seeks outlets through which to flow. The higher the pressure build-up, the greater the volcanic explosion.Full Answer >