Login   |      Register
English    中文

Famous volcanic eruption in history(Chapter Ⅱ)

2019-12-11  |   Editor : houxue2018  

Peléan eruption

The name comes from the 1902 eruption of Mount Pelee in Martinique, West Indies, which destroyed the city of St. Pierre, killing more than 30,000 people. This eruption produces high-viscous magma, which is particularly intense, the most obvious feature of this eruption is the formation of a hot volcanic ash cloud, a high-temperature gas, full of hot ash particles, like active emulsion, with a high density, which can produce hurricane-like effects when it moves downhill. In a Peléan eruption, the upward escaping gas is often blocked by lava in the crater, the pressure increases gradually, when an explosion occurs, it is like a gust of wind gushing horizontally from the bottom of a bottle plug. Lava is driven outward by gases with high ash content, but there is no outflow of lava anywhere except from the mouth of the fire. There are many Peléan eruptions in history: Corsicguana in 1835, Krakatoa in 1883, Soufriere in 1902, Katmai in 1912, Lamington volcano in 1951, Bath Miyan in 1955-1956, Maron in 1968 and El Chichon in 1982.

Plinian eruption

Magma has high viscosity and strong eruption, pyroclasts often reach more than 90%, of which the surrounding rock debris accounts for 10% ~ 25%, ejection mainly consists of rhyolitic、 coarse pumice and volcanic ash, widely distributed with a small amount of lava flow or volcanic ash flow. Because of the intense eruption and the mass ejection of magmatic material, craters with collapsed cone tops are often formed. This volcanic eruption is often a process of clearing volcanic passages - magma foaming - violent eruption of pumice and volcanic ash - debris falling into the channel wall a nd blocking the volcanic passages, thus forming complex volcanoes. The eruption of Vesuvius in 79 AD was a typical Plinian eruption, accompanied by a massive eruption of pumice, cinder and ash. The erupted cinder fell downwind, 13km from the crater of Pompeii city, buried by an average of 7m thick pumice layer. Shallow volcanic activity in Japan in 1783 also lowered the pumice layer, with both pyroclastic and lava flows erupting during the eruption. On May 18, 1980, the eruption of Mount St. Helens in the United States was also of the Plinian type, which formed a hydrothermal-magmatic explosion.

SuperWuerkano eruption

This eruption, like a steam explosion, almost an explosive eruption without magmatic material. Some are called supervolcanic eruptions. Since the eruption has only eruptive material but no lava, the eruptive material erupts in a cooling state and occasionally in a hot state. It is characterized by a large amount of basement pyroclastic material, sometimes up to 75% ~ 100%. The volume of material erupted by the SuperWuerkano type varies greatly, from giant rocks to volcanic ash. Pyroclastic is usually angular and sharp corners, without volcanic bombs and slag.

Sutser eruption

From 1963 to 1967, a continuous volcanic eruption off the coast of southern Iceland produced sutser volcanic island. During the first half of volcanic activity, a crater at the bottom of the shallow sea was characterized by repeated explosive eruptions, when basaltic magma contacts with sea water, it explodes again, producing a large amount of plasma, (ash), this eruption type of magma to water vapor, water vapor to magma is different from the Stoneboli on land.

The above classification is not the most perfect, the actual investigation reveals that even the same type of eruption may occur in different types of volcanism, and the same volcano may produce different types of eruption in its own process of activity, and even in the same period of eruption, sometimes different forms of volcanic activity will occur. For example, the Stonbury volcano named after Strombolian has several Wuerkano eruptions; Kilauea and Mauna Loa volcanoes named the Hawaiian eruption, and the eruptions from the Strombolian to the SuperWuerkano have been observed in different periods.

    Sign in for comments!

Comment list ( 0 )