Main articles: volcanic cone and Cinder cone Izalco volcano, the youngest volcano in El Salvador. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes except when the mud volcano is actually a vent of an igneous volcano. Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter, Saturn, and Neptune and mud volcanoes, which are formations often not associated with known magmatic activity. Vents that issue volcanic material (including lava and ash) and gases (mainly steam and magmatic gases) can develop anywhere on the landform and may give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Kīlauea in Hawaii. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus. The features of volcanoes are much more complicated and their structure and behavior depends on a number of factors. The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit however, this describes just one of the many types of volcano. Skjaldbreiður, a shield volcano whose name means "broad shield" Plate tectonicsįurther information: Types of volcanoes Lakagigar fissure vent in Iceland, the source of the major world climate alteration of 1783–84, has a chain of volcanic cones along its length. The study of volcanoes is called volcanology, sometimes spelled vulcanology. The word volcano is derived from the name of Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan, the god of fire in Roman mythology. For example, Mercury has pyroclastic deposits formed by explosive volcanic activity. Other planets besides Earth have volcanoes. Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool the Earth's troposphere. Volcanoes are usually not created where two tectonic plates slide past one another. This results in hotspot volcanism, of which the Hawaiian hotspot is an example. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, 3,000 kilometers (1,900 mi) deep in the Earth. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and most are found underwater. This makes silicic magmas more dangerous: As more gas builds up in the magma, it becomes more explosive, like adding more and more carbonation to a soda.For broader coverage of this topic, see Volcanism.Ī volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Since silicic magmas are colder and goopier than mafic magmas, dissolved gases have a harder time venting out of them. Why do so many people live near active volcanoes? Rhyolite, an especially silica-rich type of lava, hits temperatures between only 1,200 degrees to 1,500 degrees Fahrenheit. These magmas are more than 63 percent silica, which makes them more viscous: At their runniest, silicic magmas flow about as well as lard or caulk-which is to say not well at all. Silicic magmas, on the other hand, tend to form when the lighter continental crust melts. What are the biggest dangers from Hawaii's erupting Kilauea volcano? They're also the hottest variety of magma, reaching temperatures between 1,800 degrees to 2,200 degrees Fahrenheit. As far as molten rocks go, mafic magmas are fairly runny, with viscosities ranging from molasses to peanut butter. They contain between 47 to 63 percent silica, the mineral that makes up glass and quartz. Mafic magmas like those in Hawaii tend to form when the heavier crust that forms the ocean floor melts. Hawaii’s Kilauea volcano erupted on May 3, 2018, and the lava continues to flow.
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