Table of contents:
- What is a Volcano?
- Type of volcano
- Volcanic landforms
- Distribution of Volcanoes in the World
- Negative effects of volcanoes
- Positive effects of volcanoes
Volcanos
Types of the volcanos:
The following are the types of Volcanos- Shield volcano
- Composite volcano
- Caldera volcano
- Flood basalt volcano
- Mid-ocean ridge volcano.
- Active volcano: Release of lava recently.
Shield volcano:
- It is the largest of all volcanoes on Earth. For example, Hawaiian volcanoes.
- It is made of basalt lava and expands very rapidly when it erupts.
- If water gets into the vent it becomes explosive otherwise less explosive.
- At the top vent, it develops like a cinder cone.
Composite volcanoes:
- When the material emanating from a volcanic eruption gets mixed and solidified in several layers, it is called a composite volcano.
- It is less explosive and more viscous and thicker than basalt.
Caldera:
- It is the most explosive volcano. It collapses rather than building a tall structure.
- It makes depression called a caldera.
Flood basalt province:
- When the lava emanating from the volcano is very liquid and spreads over great distances, it is called a flood basalt volcano.
- For example, the Deccan trap in India.
Mid-ocean ridge volcano:
- It occurs in the ocean, and central portions of this ridge experience frequent eruptions.
- Volcanoes landforms:
Volcanoes landforms
Question:
Write short notes on Volcanic Structural features. ( UPPSC 2001)
- Intrusive landforms forms
- Extrusive landforms forms
Intrusive forms:
When lava cools down inside the crust to form various landforms before reaching the surface, it is called an intrusive volcanos landform.The following are the intrusive form of volcanoes' landforms:
- Sill
- Dyke
- Batholith
- Laccolith
- Phacolith;
Sill:
- When lava moves upwards during a volcanic eruption but some part of the lava moves horizontally and cools within the crust, it is called a sill.
Dyke:
- When lava moves upwards towards the surface but cools within the crust perpendicular to the ground, this wall-like structure is called a dyke.
Batholiths:
- It is a tall, irregular, and generally dome-shaped Magna that cools at great depth.
- But due to erosion over time, they come to the surface, and many batholith rocks in Chota Nagpur and Rachi plateau are still visible on the surface.
Laccoliths:
- It is similar to the batholith but shaped like a mushroom and formed at a lower depth and connected to a lava pipe.
Phacolith;
- It is found in the anticline and syncline regions of the folded mountain.
Extrusive volcano landforms
When volcanic lava comes to the surface and cools and forms various types of shapes, it is called exogenous volcanic landforms. igneous rocks are an example of lava cooling at the surface.The following are extrusive landforms:
- Cinder cone
- Composite cones
- Lava plateau
- Caldera with a cinder cone
- Volcano rock
Cinder cone:
- It is formed by volcanic dust and ashes and usually has a low height.
- For example, Mt. Jorullo of Mexico.
Composite cones:
- The height is higher than the cinder cone and is formed by different layers.
- For example, Mount Fujiyama in Japan, and Mount Hood in the United States.
Volcanic distribution in the world:
- 400 out of 500 volcanoes are found in the Pacific ring of fire(along with the convergence zone of the plates).
- Other volcano activities are found in the weak zone of the world along with the Mediterranean sea and alpine Himalayan mountain.
- Very few volcanic activities are found in Africa.
- One active volcano is found on the barren island of Andaman Nicobar.
- No volcanic activities are found in Australia.
Negative effects of volcanoes:
The following are negative effects:- There is the destruction of property and human life.
- There is a loss of crops and forests.
- It blocks the sunlight (insolation) from reaching the earth.
- Increases atmospheric temperature.
- It increases acid rain.
- If it occurs in the oceans, it can cause tsunamis.
- In 1883, the Mount Krakatoa volcano caused a tsunami that killed more than 30,000 people.
Positive effects of volcanic eruption:
The following are positive effects:
- Many new landforms are formed
- Fertile soil is formed by the decomposition of volcanic rocks.
- Volcanic dust and ash also increase fertility around areas.
- Crater lakes and hot springs are formed.
- It is a source of valuable minerals.
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