Volcanic action is affected by the nature of lava, the pressure of
underground magma reservoir, the shape of volcanic channel and volcanic
eruption environment, etc and volcanic eruption has the following types.
Fissure eruption
Fissure eruption refers to magma flows out from the huge fissure
in the crust. This kind of eruption doesn’t have strong explosion phenomena
and the ejecta is mainly basic lava, which will form a large area of
lava platform after condensation.
For example, the Permian emeishan basalt in the border area of Sichuan,
Yunnan and Guizhou province in the southwest of China and
the tertiary Hannuoba basalt in the north of Zhangjiakou, Hebei province
are all fissure eruptions. Now fissure eruptions are mainly distributed
in the ridge of the ocean floor. On land, only in Iceland can you see
such volcanic activity so Iceland is also known as the Icelandic volcano.
Central eruption
Central eruption refers to underground magma erupts through a tubular
volcanic channel. This is the main form of modern volcanic activity
and it can be divided into three types:
- Calm eruption .When a volcano erupts, only a large amount of
hot lava flows out of the crater and flows slowly along the slopes,
as if rice soup boiling rice soup is boiling out the rice cooker.
The overflow is mainly base melt, with high temperature, small viscosity
and high flowability. There is less gas and no explosion. Volcanoes
in Hawaii are representatives of this kind of volcano and they
are known as Hawaiian volcanoes
- Burst eruption.When a volcano erupts, it produces a violent explosion
and spewes lots of gas and volcanic debris. On June 25th, 1568,
the eruption of the Pelee volcano in the West Indies was one of these
and it also known as Pelean volcano.
- Burst eruption.When a volcano erupts, it produces a violent explosion
and spewes lots of gas and volcanic debris. On June 25th, 1568,
the eruption of the Pelee volcano in the West Indies was one of these
and it also known as Pelean volcano.
- Intermediate eruption.Intermediate eruption is a transitional form
between quiet and explosive eruptions. This type is dominated
by medium-based eruption. If there is an explosion, the explosive force
is small. The volcano of this type can erupt consistently for several months,
even years. The Stromboli volcano on Lipair Islands, which close
to the west coast of Italy is the respresentatives of this kind.
The volcano eruptes every 2 or 3 minutes and you can see the flame of volcanic
eruptions outside 669 kilometers. So this volcano is also known as
Stromboli-type volcano.
- Molten eruption.Molten eruption is that lava overflows the surface of land.
It is an ancient volcanic activity and not exists now. Some scholars believe
that in ancient times, the crust was thin and the underground magama
was very hot, which often resulted in the eruption of molten magma.
