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IMPACTS OF VOLCANOES ON CLIMATE

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IMPACTS OF VOLCANOES ON CLIMATE

HISTORICAL ERUPTIONS THAT HAVE THE MOST INFLUENCE ON THE CLIMATE

  • TYPES OF ERUPTIONS

Volcanologists distinguish six major types of eruptions. Below you have the types of eruptions in order of increasing intensity. An index of the power of volcanoes, the "VEI" (In English, "Volcanic Explosivity"), was imagined by Chris Newhall. This scale is multiplied by 10 when passing for example from VEI 1 to 2. So an eruption of VEI 8 is 10 million times more powerful than eruption of VEI 1.

Ejection volume, size of the cloud of the eruption, ... are factors for the VEI measure. The scale ranges from 0, for inexplosive eruptions (less than 104 m3 of ejected tephra), to 8 for the explosive eruptions of great intensity which can eject up to 1012 m3 and a cloud column over 25 km height). The values higher than 8 could be determined if necessary.

    • Hawaiian kind :

      "Hawaiian" volcano eruptions have a very fluid lava, it gushes into fountains to tens or hundreds of meters high, it flows over long distances, or it boils in a lava lake.

      The name of this type of eruption comes from volcanoes of the Hawaiian Islands. The "shield volcanoes" that emit them have low altitude compared to their diameter (with a slope of 5%). Their activity is effusive.

      Volcano eruption of this type is Mauna Loa, Hawaii, which lies at the bottom of the ocean to 5000 meters deep and its crater is 4171 meters high above the ocean. It is the highest volcano. We also have Kilauea in Hawaii, the Piton de la Fournaise on the island of Reunion, The Trölladyngja in Iceland...

Hawaiian type - VEI : from 0 to 1
    • Strombolian type :

      The Strombolian volcanoes type have an alternation of explosive and effusive eruptions (incandescent projections that do not rise very high in the sky, less than 5 km and lava flows).
      The name of this type of eruption comes from Stromboli (volcano of Aeolian Islands in Italy).

      As Strombolian volcano we have Mount Erebus on Ross Island in Antarctica, Oshima in Japan that had its last eruption in 1990, Mount Etna on the east coast of Sicily, sometimes the Piton de Furnace to the island of Reunion...


Strombolian type - VEI : from 1 to 2

    • Pelean type :

      The magma of these volcanoes is very viscous. Pelean eruptions of lava are thick and pasty. They completely solidify on contact with air. Forming a very resistant cap at the exit of the chimney, the gases trapped below push it and do it rise up by constructing slowly a lava dome. Heavy clouds of gas, ash and incandescent blocks, named fiery clouds, occasionally escape from the dome cracks and slide down the slopes. When the pressure is at maximum an explosion occurred, shattering the dome and leaving violently escape the lava.

      This category takes its name from the eruption of Mount Pelee 1902-1904, famous volcano in Martinique. As this type of volcano eruption we also Lamington in New Guinea, the Puy de Dôme in the Massif Central, asleep from about 11,000 years, the Soufriere in Guadeloupe, sometimes the Vesuvius in southern Italy...

Pelean type - VEI : from 1 to 8
    • Plinian type :

      These flares are the most violents.

      The magma of these volcanoes is thick and pasty. Their eruptions are characterized by very violent explosions the open crater projecting a large plume of ash and pumice (less dense than air) at altitudes of 10-20 km in the form of umbrella pine tree (to distinguish from the fiery cloud) . Upon reaching the atmosphere, the gases trapped in the magma expand and give birth to whitish ash. These eruptions are less frequent than the others but do much more damage and casualties.

      The name of this type of eruption comes from Pliny who described the eruption of Vesuvius in 79 AD. As volcano with plinian eruption there are Mount St. Helens in the US which has experienced a rash to this type in 1980, the Santorini in Greece, the Pinatubo in the Philippines, Mount Pelee sometimes,...

Plinian type - VEI : from 4 to 8
    • The types of submarine eruptions :

      The types of submarine eruptions are classified into two families of eruptions that are produced by the meeting of water and magma.

      • Surtseyan type :

        This type of eruption is a sub type of Hawaiian eruptions for shallow submarine eruptions. They are particularly explosive due to contact with water and larva, forming a column rich in water vapor, horizontal and radial clouds. Volcanic islands often born after several surtseyennes eruptions.

        The name of this type of eruption comes from Surtsey in south of Iceland, which erupted in 1963. As with this type of volcano eruption there are Ambrym, Mont Saint-Loup Cap d'Agde...

      • Under-water type :

        This type of eruption is characterized by the emission of lava under a body of water. When the lava comes into contact with the water while it is covered with a thin layer of hardened lava fracturing under the pressure of the liquid still lava, then giving birth to cushion lava. Then the water warms at contact with the lava and when the water pressure is low enough, it vaporizes and can back up to the surface forming a volcanic plume formed mainly of water vapour.

Type surtseyen - VEI : from 2 to 5
      • Vulcanian type :

        The volcanoes of this type are made of very thick and very viscous lava which block the volcanic chimney. Then an explosion occurs when the pressure is at maximum by pulverizing the lava that gushes into the sky. Up to a height that can reach 25 km, blocks of several tons and microscopic ashes are projected by the eruption. Often a huge explosion makes blow up the crater and created a large depression from where born a new volcanic system.

        The name of this type comes from an Italian volcano in the Aeolian islands, called Vulcano. As vulcanian volcano there is also the Fuego in Guatemala it last erupted was in October 1974, Sakurajima in Japan...

Vulcanian type - VEI : from 2 to 5
    VEI
    Classification
    Description
    height of smoke
    Ejected volume
    Frequency of eruptions
    Exemple
    Total historical eruptions from 1994
    0
    Hawaiian
    non-explosif
    < 100 m
    > 1000 m³
    frequent
    Kilauea,...
    -
    1
    Hawaiian /
    Strombolian
    small
    100-1000 m
    > 10,000 m³
    frequent
    Stromboli, Peak of the Furnace...
    -
    2
    Strombolian /
    Vulcanian
    explosif
    1-5 km
    > 1,000,000 m³
    each week
    Galeras
    in 1992
    3477
    3
    Vulcanian
    severe
    3-15 km
    > 10,000,000 m³
    annually
    Nevado del Ruiz
    in     1985...
    868
    4
    Vulcanian /
    Plinian
    cataclysmic
    10-25 km
    > 0.1 km³
    10 years
    Galunggung
    in     1982
    278
    5
    Plinian
    paroxysmal
    > 25 km
    > 1 km³
    100 years
    Mount St. Helens
    in     1980
    84
    6
    Plinian /
    Ultra-Plinian
    colossal
    > 25 km
    > 10 km³
    100 years
    Krakatau
    in 1883
    39
    7
    Ultra-Plinian
    super-colossal
    > 25 km
    > 100 km³
    1000 years
    Tambora
    in 1815
    4
    8
    Ultra-Plinian
    mega-colossal
    > 25 km
    > 1000 km³
    10,000 ans
    Toba eruption
    75 000 years ago
    1



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