Volcanic eruptions are classified
in two types depending upon the manner of ejection of the magma:
1. Central Eruption
2. Fissure eruption
Central eruption : - This type of eruption is sometimes very explosive , because lava , steam , gas , dust , smoke , stone fragments are ejected from a narrow pipe from beneath
the ground surface . The substances emitted in this type of eruption give rise to conical or dome-shaped hills.
Some examples of volcanic mountains formed due to central eruptions are Mt.Kilimanjaro in Africa , the fujiyama in
Japan , and the Vesuvius and Mount
Etna in Italy . In India , there was a Volcanic Eruption on the barren Island
( Andaman group of Islands ) in 1994 .
Fissure Eruption : - A very long fissure develops in the ground surface and so
, the molten rock , rock fragments , steam and gases within pour out slowly . These Eruptions take place at a very slow speed
. As this lava is more fluid , it spreads over longer distances .The lava cools
down on the ground surface in that area . Basalt plateaus are formed from these eruptions . In very ancient times a huge crack
developed in the earth’s crust parallel to the western coast of India . From this crack , the lava poured out a number
of times and spread over extensive stretches of land . Basalt rock was created from this lava and the Deccan plateau came
into existence . Such Basalt plateaus are aslo found in Brazil in South America and Saudi Arabia in West Asia .In Maharashtra
, the fertile black regur soil has formed from basalt rocks .