What is earthquake? Write full definition …

When the earth’s surface shakes, the phenomenon is referred to as an earthquake. Precisely, the sudden trembling of the earth’s surface is the cause of an earthquake. Earthquake is regarded as one of the deadliest natural disasters. Huge damage and loss of property are caused by earthquakes. There are various types of earthquakes. Some of them are severe in nature. The most dangerous thing about an earthquake is that it is quite unpredictable. It can cause several damages without any previous indication. The intensity of an earthquake is measured by the Richter’s scale. Generally, earthquakes occur due to the movement of tectonic plates under the earth’s surface.

Types of Earthquake - There are four kinds of earthquakes namely Tectonic Earthquake, Volcanic Earthquake, Collapse Earthquake and Explosive Earthquake.

1. Tectonic Earthquake - It is caused due to the movement of the slab of rocks of uneven shapes that lie underneath the earth’s crust. Apart from that, energy is stored in the earth’s crust. Tectonic plates are pushed away from each other or towards each other due to the energy. A pressure is formed because of the energy and movement as time passes. A fault line is formed due to severe pressure. The centre point of this dispersion is the epicentre of the earthquake. Subsequently, travelling of the waves of energy from focus to the surface causes the tremor.
2. Volcanic Earthquake - The earthquake caused by volcanic activity is called a volcanic earthquake. These kinds of earthquakes are of weaker magnitudes. Volcanic earthquakes are categorised into two types. In the first type, which is called volcano-tectonic, shaking happens due to input or withdrawal of Magma. In the second type, which is termed as Long-period earthquake, tremors occur due to changing of pressure among the earth’s layers.
3. Collapse Earthquake - Collapse Earthquake is the third type of earthquake occurs in the caverns and mines. This is another example of a weak magnitude earthquake. Mines are collapsed due to underground blasts. Consequently, seismic waves are formed due to this collapsing. Earthquakes occur because of these seismic waves. 
4. Explosive Earthquake - The fourth type of earthquake is called an explosive earthquake. This is caused due to the testing of nuclear weapons. 

Effects of earthquake are very severe and deadly.

1. It can cause irreparable damage to property and loss of human lives. The lethality of an earthquake depends on its distance from the epicentre. 
2. Damage of establishments is the direct impact of an earthquake. In the hilly areas, several landslides are caused due to earthquakes.  
3. Another major impact of an earthquake is soil liquefaction. Losing the strength of water-saturated granular material is the cause behind this. The rigidity of soil is totally lost due to this.
4. Since the earthquake affects the electric power and gas lines, it can cause a fire to break out. 
5. Deadly Tsunamis are caused due to earthquakes. Gigantic sea waves are caused by the sudden or abnormal movement of huge volumes of water. This is called an earthquake in the ocean. When the tsunamis hit the sea coasts, they cause a massive loss of lives and properties.

Earthquake is termed as one of the most huge and lethal natural disasters in the world. It proves the fact that human beings are just nothing in front of nature. Sudden occurrence of earthquakes shocks everyone. Scientists are working rigorously to prevent the damage of earthquakes, but nothing fruitful has been achieved yet.