Earthquakes are one of the most destructive natural hazards. They may occur at any time of the year, day or night, with sudden impact and little warning. They can destroy buildings and infrastructure in seconds, killing or injuring the inhabitants.

But what is an earthquake? It is the sudden shaking of the earth's crust. The impact of an earthquake is sudden and there is hardly any warning, making it impossible to predict.

Cause of Earthquake :

• To understand the causes of earthquakes, let us look below the earth�s crust, where the earthquake originates.
• The outer layer of the earth is solid and is divided into many sections known as plates. In fact, these plates form the base, on which all the continents stand.
• However, these plates are not stationary but float over the molten magma that flows beneath the earth�s crust, these plates move slowly, taking the continents along with them.

Sometimes, during the course of their movement, these plates move against each other, and many of the earthquakes occurred at the edges of these plates. Which are the fault lines, where the plates collide or slide past each other.

In addition to tectonic plate movements, earthquakes are also caused by volcano eruptions. Apart from these natural causes, there are other manmade causes, these include, vibration caused by big rocks falling down from the mountains because of erosion and in the present times due to nuclear explosions.

In addition to knowing why an earthquake occurs, scientists can also tell the point of origin of the earthquake. This point of origin is called the 'focus' and may be located near the surface or deep below it. The point on the surface directly above the focus is termed as the 'epicenter of the earthquake

Measuring Earthquakes

Earthquakes can be measured using a device called a seismometer and a device that also records is known as a seismograph. They use an instrument to measure the magnitude of the earthquake, called a Richter scale.

The big earthquakes not only occur on land but also in the sea. Such earthquakes give rise to giant waves called tsunami, which cause a great deal of destruction. Do more than 10 lakh earthquakes occur every year in different parts of the world? In fact, 2/3rd of the earthquakes occur in the area of ring of fire in the Pacific Ocean.

In India, places like Kashmir, western Himalayas, middle Himalayas, northeast India, plains of Ganga and Indus, Rajasthan, Gujarat, Lakshadweep and Andaman, and Nicobar island are earthquake-prone regions. All the regions which lie in the earthquake zone often face a huge amount of destruction. The destruction includes damage to building, roads, railway lines and also result in huge loss of life.

In hilly areas, earthquake often leads to landslides and in the coastal area's earthquake can lead to a tsunami.

Prevention

Now it is important to take certain steps before, during, and after an earthquake strike, so as to limit its damage.
1. The information about the earthquake and its intensity should be communicated to the people through various means of communication.
2. The government should promote buildings, which are constructed on earthquake resistance techniques.
3. Techniques like construction building over pillars, which are made of concrete and iron, which are built deep in the ground.
4. In order to deal with the emergency, stuff like water, ration, medicines, flashlight, radios, blankets, etc should be stored in safe places.

But what should be done, when an earthquake strikes�:

1. During the event of an earthquake, make sure to be calm, and if inside a building, try to take shelter under a solid surface like a table or stand in the doorway.
2. If one is outside, then one is advised to move to an open space, away from trees, electric poles, and buildings.
3. If possible one should switch off the gas and electric supply
4. Once the quake is over, the affected people should be given immediate medical help.
5. Telecommunication and electricity should be restored, so as to help in the rescue work.
So, we see that we can do a lot of things before, during, and after an earthquake to limit the damage caused by it. As a student of disaster management, it is very important to take care of these points.

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