Nature continues to amaze us every day with its marvels. Today, even though we appear stationary, we are travelling at a speed of 465 meters per second. Similarly, inside the earth, there are constant movements that are happening. The tectonic plates of the earth’s crust are also moving at an average annual rate of around 10cm.
You may ask, “So what if the tectonic plates are moving?” Well! It is significant because it is these movements that have caused the Himalayas and the Atlantic Ocean to appear. These were not present on the earth, millions of years ago. Now, it is the movement of these same tectonic plates that make the earth spew out volcanoes, which have the material from the insides of the earth.
What does the earth have inside that it can spew out volcanoes? Is earth a solid planet?
Well! The earth is actually not a solid planet. It has many layers and each layer has different components like solid rocks, minerals, gases, molten rock etc. The outermost layer that you can see is called the crust. What you see of the earth’s surface, the crust, is a superficial thin layer. Below the crust are the layers of mantle and core which are very deep. To get an idea, you can compare Earth with an apple. The earth’s crust is similar to the peel of the apple, while the mantle and the core are the pulp of the apple.
The earth’s crust has many elements, minerals and rocks. The crust is also divided into huge plates or pieces of rock that float above the mantle layer of the earth. These plates are called the tectonic plates which are in constant motion, moving at an average annual rate of around 10cm. These plates can either come towards each other or drift away from each other or even slide up or sink down.
How volcanoes are formed
Deep down in the earth’s mantle and core, the temperatures are extremely high. They also contain molten rock material called the magma and other gases. These gases exert a lot of pressure. And it is because of this gas pressure, the hot molten rock material comes out of the earth’s crust. When the magma comes out of the earth’s crust, it is called lava. As the lava flows out, in its liquid form, the temperature can range between 700 to 1,200 °C. It is very viscous and can flow great distances. As the lava cools down, it solidifies to form igneous rock. The catastrophic effect of the lava coming out of a volcanic eruption is so huge, that it can destroy everything that comes in its path. When volcanoes erupt, they give out not only the hot molten rock material but also dense volcanic ash. This ash has the capability of destroying the visibility of the nearby areas.
Any volcano that has recently erupted, with a possibility of it erupting again, is called an active volcano. A dormant volcano is one which has not recently erupted. But there are always chances that it can erupt in the future. There are also a few volcanoes that are extinct. An extinct volcano is one which erupted thousands of years ago with no possibility of an eruption.
Did you know that the greatest number of volcanoes occurs deep down on the ocean bed? A belt called the “Ring of Fire” in the Pacific Ocean has the most number of volcanoes. It has around 452 volcanoes which are active and dormant.