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Volcanic eruption is one of the best known forms of volcanism , manifested by the elimination of different amounts of material from the chamber or magma reservoir of the volcano . Several types of volcanic eruptions - in which lava , pyroclasts ( ash , lapilli, volcanic bombs and volcanic blocks) and assorted gases are expelled from a volcanic channelor a crack - were distinguished by volcanologists. They are often named after famous volcanoes, where this type of behavior was observed. Some volcanoes can present a single characteristic type of eruption during a period of activity, while others can display a whole sequence of types, all in a single eruptive series.
The usual conical shape associated with volcanoes that are born by successive overlapping layers of lava and ash that erupt from a main chimney. Not all volcanoes have this shape. For example, the thin, fluid lava of Hawaii forms flat, shielded volcanoes , while the fluid lava that erupts from a fissure rather than a chimney forms stepped plateaus such as the Deccan Plateau in India . Volcanic domes are formed by the slow eruption of thick lava. If the volcanoes have been dormant or extinct for some time, the central part of the cone may collapse inward, forming a large circular crater called the caldera .
1. Vulcanic Dome - Raised by the slow eruption of thick, viscous lava.
2. Volcano-shield - Low altitude cone, typical of Hawaii
3. Stratovolcanoes - Classic, steep lava cone and layers of ash.
4. Boiler - Collapsed cone. Lakes often form in these craters.
How a volcano erupts depends on the composition of the lava and the amounts of gas it contains. The denser the lava or the higher the amounts of gas, the more violent the eruption. The types of eruptions are determined by typical specimens - with the exception of the Plinian one, which bears the name of Pliny the Elder who described the eruption of Vesuvius in 79 AD. Some volcanoes, such as Etna , erupt in different ways, depending on the pressure level and the lava content.
1. Peleană - Dense lava, very gaseous; explosive eruptions and gas clouds.
2. Hawaiian - Fluid lava, fire fountains, non-explosive eruption.
3. Strombolian - Fluid lava with high gas content. Small, frequent explosions.
4. Plinian - Explosive eruption ; ash and scrap are blown very high in the air.
5. Vulcanian - Rare, explosive eruptions; he throws ashes and rocks at great distances.
10,000 volcanoes have been identified in the world, of which 500 are active.
1. The highest volcano on the seabed - Mauna Loa in Hawaii : Although it is only 4,170 m above sea level, Mauna Loa rests on the seabed. Measured from there, it is not only the highest volcano in the world, but also the highest mountain with 10 200m.
2. The highest active volcano above sea level - Cotopaxi in Ecuador : With a height of 5,911 m, Cotopaxi erupted 50 times since 1738. The last known eruption occurred in 1904, and in 1975 the volcano awoke for a short time .
3. The most active at present - Kilauea in Hawaii : Kilauea has been erupting continuously since 1983 at a rate of about 5 cubic m / sec of lava. Kilauea means "spitting" or "scattering".
4. The most active in history - Stromboli in Italy : The weak but continuous eruptions of Stromboli , located on the Aeolian Islands, have been recorded since Roman times, which gave it the nickname "Lighthouse of the Mediterranean".
5. Most Tambora victims in Indonesia : The Tambora eruption of 1815 raised a 44km high column of ash. 10,000 people died as a result of the eruption, and another 82,000 died of starvation and disease.
6. Potentially most dangerous Vesuvius in Italy : in 79 AD. the eruption of Vesuvius destroyed the Roman cities of Pompeii and Herculaneum . A similar eruption today would have devastating effects in this densely populated region.
7. The biggest Krakatau explosion in Indonesia : Krakatau , in the Sunda Strait , exploded in 1883 destroying almost the entire island and forming a tsunami that killed 36,000 people.
