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In this article, we would discuss a volcano’s eruptive styles and the distribution of volcanoes in the world.
Eruptive styles
1. There are two types of volcanic eruptions: fissure eruption and central eruption.
2. Fissure eruption: The lava or the pyroclastic material emerges simultaneously at various sites along a linear fracture. Fissures develop over time due to shifting of the Earth’s crust and the cumulative effect of lava and steam boiling inside.
3. Fissure eruption occurs when lava, gases and rock fragments spill through the cracks. The fluid lava goes away from the fissures and does not take the form of cones.
4. Deccan Plateau in India is an example of the fissure lava eruption that took place about 60 – 62 million years ago.
5. Central eruption: They are much like point source eruptions unlike the linear source in case of fissure eruptions.
6. The lava emerges from a central vent and takes the form of a cone-shaped structure.
7. The lava is viscous and thus moves slowly. It produces volcanic domes (also known as lava dome; it is the magma piled up around the volcanic vent).
Distribution of volcanoes in the world
1. Volcanoes are located in a clearly defined pattern around the world.
2. These are closely related to regions that are intensely folded and associated with places where the Earth’s crust is actively changing.
3. There are over 500 active volcanoes and thousands of dormant and extinct ones.
4. They mostly occur around coastal mountain ranges, offshore islands and in the middle of the oceans. Few may occur in the interior of the continents.
5. The greatest concentration of volcanoes is around the Pacific Ocean known as Circum – Pacific region, popularly termed as Pacific Ring of Fire.
6. Another chain exists in the Mediterranean area and in the rift valley of Eastern Africa.
7. Hawaiian and Aleutian Islands were created due to repeated volcanic activity over the years.
8. The ejected material from the volcano is absolutely fertile and the geothermal heat is an important source of alternate power.
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