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Pyroclastic flows sweep down the flanks of Mayon Volcano, Philippines, in 2018. A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) [1] 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 average speeds of 100 km/h (30 m/s; 60 mph) but is capable of reaching speeds up to ...
The most important characteristic of a Peléan eruption is the presence of a glowing avalanche of hot volcanic ash, called a pyroclastic flow. Formation of lava domes is another characteristic. Short flows of ash or creation of pumice cones may be observed as well. The initial phases of eruption are characterized by pyroclastic flows.
A pyroclastic surge is a fluidised mass of turbulent gas and rock fragments that is ejected during some volcanic eruptions.It is similar to a pyroclastic flow but it has a lower density or contains a much higher ratio of gas to rock, [1] which makes it more turbulent and allows it to rise over ridges and hills rather than always travel downhill as pyroclastic flows do.
Temperatures as high as 850 °C (1,560 °F) [56] are known to occur in pyroclastic flows, which will incinerate everything flammable in their path, and thick layers of hot pyroclastic flow deposits can be laid down, often many meters thick. [57]
A rabbit's ear, with its blood vessels close to the surface, is an essential thermoregulator, [1] since rabbits cannot sweat. The additional weight of a longer or thicker ear is not always fully supported by the rest of the ear structure, resulting in ears that droop.
Hemodynamics explains the physical laws that govern the flow of blood in the blood vessels. Blood flow ensures the transportation of nutrients , hormones , metabolic waste products, oxygen , and carbon dioxide throughout the body to maintain cell-level metabolism , the regulation of the pH , osmotic pressure and temperature of the whole body ...
Fumaroles may occur along tiny cracks, along long fissures, or in chaotic clusters or fields. They also occur on the surface of lava flows and pyroclastic flows. [11] A fumarole field is an area of thermal springs and gas vents where shallow magma or hot igneous rocks release gases or interact with groundwater. [12]
A'a lava flows are denser and more viscous than pahoehoe, and tend to move slower. Flows can measure 2 to 20 m (7 to 66 ft) thick. A'a flows are so thick that the outside layers cools into a rubble-like mass, insulating the still-hot interior and preventing it from cooling.