Hi friends! It was a very lazy rainy day. I was shuffling through my book shelf to find something interesting to read. But sadly, I had read all the books. I glared at the clock and remembered that it was time for my favourite TV show, “Our planet -Our Earth”. I hurriedly grabbed the remote and frenziedly tried to tune into the channel. I jumped on my couch to see what new would be featuring today. The host of the show quite animatedly described todays topic – “The Volcanoes”. I have always been curious on how can a whole mountain erupt? Here’s what I got to know:
Structure of the earth
The earth is made up of several layers. At the top is the crust- the thinnest layer. Next is the mantle, the solid bulk of earth’s interior and then the outer and inner cores. The outer core is liquid and inner core solid.
What is a volcano ?
Volcanoes are mountains that spit out burning ash, gas and liquid rock. The ash and rock come from deep under the ground. They burst up through cracks in the earth’s crust. Some volcanoes erupt quietly with gentle flow of materials. Others explode with a loud bang sending material high in the sky.
Types of volcanoes
Volcanoes can be active, dormant or extinct. Active volcanoes are those that would have had recent eruptions or are expected to erupt soon. Dormant volcanoes are inactive volcanoes. They no longer cause eruptions, but may cause eruptions sometime again in the future. Extinct volcanoes are dead volcanoes. They are likely to never erupt again.
Causes of volcanoes
Volcanoes occur when the inner material which is significantly warmer erupts on the surface of the earth. This erupted material is called lava or liquid rock. When on the surface it is called as liquid lava and when underground it is called as “magma”.
The shift of inner layers or plates within the earth’s surface causes this magma to push upwards and it gets erupted in the form of a volcano. Also, if these plates move close to each other , they cause the magma to push inside and then create a high pressure leading to eruption. Also, there are some hot spots on the Earth or hot areas which cause the magma to heat and then lead to a volcanic eruption.
Damage done by volcanoes
Eruptions occurring close to human settlements cause a massive destruction to life and property. The thick ash emitted by the volcanic eruptions cause difficulty in breathing and it may pollute the atmosphere in and around the volcanic region.
Benefits of volcanic eruptions
The ash and lava breakdown and become rich fertile soil which is high in nutrients and useful for crop planting activities.
Major volcanic eruption locations
• Vesuvius, Italy :
On 24 August AD 79, Mount Vesuvius erupted with little warning, engulfing the Roman city of Herculaneum in a mud flow. Nearby Pompeii was buried under a vast layer of pumice and volcanic ash. As many as 20,000 people died. Vesuvius erupted again in 1631, killing up to 18,000 people.
• Mount St. Helens, Washington :
On May 18, 1980, Mount St. Helens in Washington, USA erupted causing approximate 57 deaths and is estimated to have travelled as 400 km/hr. This eruption caused a huge damage to the property and deposited ash in 11 U.S states and 5 Canadian provinces.
•Volcanoes in India :
Barren Island situated in Andaman and Nicobar Islands, India, has the only active volcano in South Asia. It is the only active volcano along a chain of volcanoes from Sumatra to Myanmar.