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At the surface expression of such hydrothermal systems, low-temperature volcanic gases (<400 °C) are either emanating as steam-gas mixtures or in dissolved form in hot springs. At the ocean floor, such hot supersaturated hydrothermal fluids form gigantic chimney structures called black smokers , at the point of emission into the cold seawater .
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 ...
A fumarole (or fumerole) [1] is a vent in the surface of the Earth or another rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcanic activity , but fumarole activity can also precede a volcanic eruption and has been used for ...
Fumaroles, or volcanic vents, are holes in the ground from which volcanic vapors and gases escape to the atmosphere. Geothermally active areas are often located over an active magma chamber, which constantly releases hot gases that travel to the surface through cavities in the rock. Where these cavities reach the surface they form fumaroles.
The volcanic materials form a vertical column or plume that may rise many kilometers into the air above the vent of the volcano. In the most explosive eruptions, the eruption column may rise over 40 km (25 mi), penetrating the stratosphere. Stratospheric injection of aerosols by volcanoes is a major cause of short-term climate change.
A volcanic eruption is essentially the only natural way for short-lived – less than a few years – gases like sulfur dioxide and water vapor to make it into the stratosphere.
It consisted of very hot volcanic gases, ash, and pumice formed from new lava, as well as pulverized old rock, which hugged the ground. Initially moving about 220 mph (350 km/h), the blast quickly accelerated to around 670 mph (1,080 km/h), and it may have briefly passed the speed of sound .
The principal gases released during volcanic activity are water, carbon dioxide, hydrogen, sulfur dioxide, hydrogen sulfide, carbon monoxide and hydrogen chloride. [12] The sulfur and halogen gases and metals are removed from the atmosphere by processes of chemical reaction, dry and wet deposition, and by adsorption onto the surface of volcanic ...