Tectonic plate movements and earthquakes Topic-2

 Tectonic plate movements and earthquakes

Topic 2

Post was delayed due to personal issues. Anyway, today will be a topic of discussion. That is - why are tectonic plates moving? However, in the previous topic, there has been some discussion about what tectonic plates are and the structure of the earth. I would like to request that you must see the first topic before reading this topic. Otherwise there is a 90% chance of problems or difficulties in understanding, if you do not know about the internal structure of the earth. Link:

Anyway, there is little to say here. (See Figures 1, 2 and 3, of course). The outermost, hardest earthen part of the earth is called the crust. Then there is a huge layer of silicate rock on the inside - the mantle and then the innermost molten metal ball-like part - the core. The lower part of the crust and the upper part of the mantle are made up of several fragile rocks, collectively called the lithosphere. And each of these rocks is called tectonic plate. Note, say plate but not food plate6. However, there are 12 such major and numerous smaller plates. They move very slowly - only a few centimeters per year, at the rate at which our fingernails grow. At the same time, they are the heaviest rocks in the world. Although the speed of these huge plates is very slow, the overall slow speed requires a lot of energy. And this energy comes from the internal heat energy of the earth. So what is the process? Let's take a look. But before that we need to know some basic things about heat transfer.

We know that heat flows from a warm object or a place to a cool object or place in three processes. Transport, circulation and radiation 6 When heat is transferred from the warmer part of the material to the cooler part of the corner, but the molecules of the substance do not move, it is called transport. For example, when one side of an iron is heated, the other side is automatically heated. Again, the process by which the molecules of matter themselves move and conduct heat is called convection. For example: boiling water. However, the process by which heat is transferred from one place to another without any inert medium is called radiation. For example, heat from the sun.

We know that there is intense heat inside the earth. There are basically two sources of this heat. First, since the creation of the earth, there has been a great deal of heat accumulated inside the earth, the core of which is almost molten. And secondly, there are different radioactive elements in the interior of the earth And as a result of their spontaneous breakdown, heat is also being generated. As a result of these two, some part of the total heat gradually comes out from the inside to the surface of the earth and is released into the air. The method by which this heat comes from the inside of the earth and radiates outside is called convection. And, the various liquids and gases inside the earth carry this heat towards the surface. But, how does this process of heat occur again?

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Before we do that we notice an event in our daily lives. A special process occurs when we boil water in a pot or container. (See Figure 4). You see, the water keeps coming up from the bottom to the top in a continuous cycle. We call this state of heated water boiling water. At a pressure of 1 atm about 100 ° C. It happens in temperature. What actually happened here? Because the lower part of the pot is in direct contact with the fire, that part heats up more than the other part of the pot - which heats the water in the lower part of the pot much more than the upper part. As it heats up, the water there becomes lighter and expands than other parts of the pot. As the mass of water remains the same, but its density decreases as the volume increases. For buoyancy, the light water rises to the top, and as the water at the top is relatively less heated or cooler than it is, it becomes heavier and sinks to the bottom. At the same time the heated water rising from the bottom of the east cools down a bit by then and becomes heavy again. Then it goes down again inside the pot and the cool water of the east is heated by that time and becomes light and starts coming up. As long as the water is heated, this process continues in a continuous cycle As water is constantly heated in this way, its particles constantly change position (continuously from bottom to top and from top to bottom). This process is known as convection. Exactly the same process takes place inside the earth.

As we have already seen in the last post, the temperature at the core of the earth reaches 6000 ° C. Due to this extreme heat, the minimum temperature of the mantle or the part adjacent to the core is very high. Due to this extreme heat, the mantle material adjacent to the core is in a very molten state. Note that these molten substances are called Magma 6 At the same time, a huge amount of gas has been stored underground. Due to the heat of the core, the gas and liquid (magma) of the part adjacent to the core are heated and expanded. As the density decreases, it tends to rise upwards (which is exactly what happens when water boils). This is because the temperature of the upper part of the mantle, i.e. the part adjacent to the crust, is much lower than that of the part adjacent to the core, so that the substances are relatively heavier and compressed. Due to gravity, they sink inwards or downwards towards the core.

Then, as the previously heated material of the adjacent part of the core rises to the top, it comes close to the tectonic plate and binds, releasing heat and shrinking to relatively cold. As a result their density increases. 

It then sinks again and returns to the area adjacent to the eastern core, and then the previously heated material rises again. In this way heat flows continuously through the motion of the substances in a continuous cycle. The periodic motion created by objects as they rise and fall in a circle is called convection current. And, in the case of planets, this convection current occurs only at their mantle level. (See pictures 5 and 6)

The heated substance rises to the top and travels to the mantle adjacent to the tectonic plate. It then cools down and spreads out before sinking again, as they are lighter. At the same time the substances push the plates upwards. As it spreads again, it cools down and moves forward a little way before it sinks to the bottom, pushing the adjacent plates forward. This causes the plates to move very slowly along with the substances. And, this is why tectonic plates are moving.

Stay tuned for now. The next topic will discuss earthquakes and the role of tectonic plates behind them.