The earth we live on is a beautiful yet complex creation with many things happening simultaneously over and under its surface. The stable Earth’s surface suddenly starts shaking heavily, causing everything on it to move. This movement is sometimes so strong that it can cause buildings to collapse and tear the land. This occurs due to entirely natural activity and is called an earthquake. It may last for a few seconds at a time, with aftershocks occurring in intervals.
It has always been a subject of study, with experts trying to find the reasons behind it, causes, effects and outcomes. With the advancement in technology, scientists have been able to understand what happens underground during an earthquake that destroys the surface.
What is an Earthquake?
An earthquake can be defined as the movement in Earth’s crust as a result of the displacement of large earth blocks or plates. The point where this happens is called the hypocenter. The main earthquake is the mainshock that may have foreshocks and aftershocks. Foreshocks are less common and happen before the mainshock. On the other hand, after the mainshock, aftershocks are more common. The aftershocks are lower in intensity and can happen for several days or weeks. In some situations, they can last for months or years also.
Types of an earthquake
There are three different types of earthquakes as classified by experts. Following are them.
- Volcanic earthquakes
- Collapse earthquakes
- Explosion earthquakes
These types differ from each other based on causes, intensity and effects.
Diving into the details of this natural calamity can be very interesting. Students studying geography and other related subjects usually get assignments related to earthquakes, for which they seek help from cheap assignment writing service uk. They can conduct interesting practicals and experiments to understand the subject better.
Before discussing the detail of what happens during an earthquake, have a look at why earthquakes happen.
How does it happen?
The Earth’s crust has many faults that move after some time. Some of them do not move for a long time. Even if they do not move, the rocks covering their sides erode and deform as a result of tectonic forces. When the rocks deform too much, they break and sometimes result in huge and rapid movement in the fault. This movement translates into shaking the land at the surface of the earth, which is termed an earthquake.
Once the rocks are broken, the plates keep moving until they find a spot to get stuck and settle down. The point where the deformed rocks break and generate an earthquake is known as the focus underground, and at the surface, it is known as epicentre.
What Happens underground?
The impact of an earthquake on the earth’s surface is quite obvious, but people are curious about what happens underground during an earthquake. Here is a description of some of the things that happen under the surface of the earth.
Generation of Seismic Waves
The movement generated by the rocks and plates is carried to the Earth’s surface through seismic waves. These waves refer to the waves of energy that come into action when the energy is released underground at the “focus”. This energy then travels to the surface in all directions from the focus. You can understand this with the movement in water when you throw a rock into it. The seismic waves carry this energy and are strong enough to pass through all forms of matter, including solid, liquid and gas. As the waves pass through them, they cause them to shake and vibrate. Humans can feel them when they reach the surface. The intensity at the focus and the surface may differ depending on the energy released.
Earthquakes are sometimes the result of underground volcanic activity also. The earth’s crust contains a hot liquid called magma that moves through creases and cracks. It is the same liquid that comes out of a volcano and is known as lava. During its movement under the earth, it may sometimes move to a place where there is an obstacle hindering the smooth flow. The impact of this blockage is felt like an earthquake at the surface.
Magma keeps flowing due to its liquid nature and leaves empty spaces behind. These spaces allow rocks to move into them. This occupying of empty spaces results in causing intense earthquakes that can cause heavy destruction.
What are Tectonic Plates?
The Earth’s crust has various gigantic plates made up of rock. These plates keep moving gradually and are known as tectonic plates. The movement in these plates is caused by the change in temperature in the Earth’s crust and is very minute. Since the movement is slow, it is not felt at the surface. However, over time, such as a year, they may result in moving around an inch or more distance. The movement can be in any direction.
Why does the earth shake during an earthquake?
The earthquake is felt when the earth shakes, and the same happens with buildings, vehicles, trees, and other things on the surface. But why does it happen? Here is the answer. During the movement between tectonic plates under the surface, their edges collide. The energy between them finds no place to escape and usually is stuck there. The energy finds a place to release when friction acts upon the sliding edges of the blocks. This energy on releasing reaches the surface and causes it to shake along with all other things.
Earthquakes and technology
Despite all the progress in research regarding earthquakes, it is not yet possible to forecast them in advance. It seems quite impossible in the near future, but it might happen with more progress and advancement in technology. Experts have been working and trying to find a way to do so. If scientists can do so, the risk of casualties and destruction can be minimised significantly.
However, the intensity of an earthquake can be measured with the help of a raster scale. This helps estimate the aftershocks’ intensity, which is always less than the mainshock. Also, the location and focus of the earthquake can be calculated to understand the areas more prone to earthquakes.