An earthquake is the sudden shaking of the earth which releases the energy in the earth’s lithosphere causing the creation of seismic waves. It may be due to volcanic eruptions, moving of tectonic plates, the formation of the cave in small area or explosions. It is also called quake( or tremor or temblor). It is measured with a Richter Magnitude scale. Causes and Effects of an earthquake are:
(Note: During an earthquake, do not hide under the staircase because it is the weakest part of the buildings and structures.)
Causes of earthquake:
- Volcanic eruption
- Moving of tectonic plates
- Formation of the cave in a small area
- Explosion and blasting
- Heavy vibrating machines
Effects of earthquake:
1. Ground Shaking
During an earthquake, different seismic waves are produced either horizontal or vertical. Seismic waves cause the shaking of structures in all possible directions. This makes the structure weak by making the joints loose and sometimes causes tilting and the collapse of structure which may lead to loss of life and property.
If an earthquake lasted for a long time then the effect of ground shaking will be more leading collapsing of more structures and losses of lives of humans and animals.
With the help of ground accelerator; ground shaking is measured.
2. Liquefaction of soil
Liquefaction of soil is one of the alternative effects of ground shaking. When water-saturated granular material like sand loses its strength temporarily it gets converted into a liquid state from solid; liquefaction takes place.
This generally causes sinking and tilting of rigid structures like buildings and sometimes leads to complete collapsing of the structure.
3. Settlement of soil
The shaking of an earthquake acts like a natural vibrator for soil causing the removal of air voids and shifting of water present in soil from one place to another by means of natural pressure. This causes the settlement of soil in high extent.
It results in the settlement, tilting and sometimes may lead to the complete collapse of structures.
4. Ground Rupture
The visible breaking and displacement of the Earth’s surface along the trace of the fault, which may be small or large in extent. During shaking of an earthquake, stresses are produced in the ground leading to ground rupture.
Structures like Dams, Nuclear Power Stations, Bridges, tunnels, pipelines, roads etc are at high risk of Ground Rupture.
An earthquake causes slope instability by shaking the slopy land in all possible directions. This causes the landslides that result in the loss of thousands of lives and properties. Sometimes landslide is so big that it nearly destroys the hill completely.
It is the indirect effect of an earthquake which may be caused by landslides, breaking down of dams, etc.
7. Human Impacts
As we know that an earthquake causes shaking of the ground along with different forms ( Horizontal or vertical ) of seismic waves. If an earthquake lasts for a longer time and its extent is high; this may cause diseases like heart diseases, panic attacks and depression in survivors.
Thousands of peoples die every year because of earthquakes. The structures we lived in are rigid in nature and effects of the earthquakes is more in such structures. It is so much sudden that maximum people do not get the chance to escape.
After pollution, an earthquake is the big killer of lives in the world.
Tsunami is derived from the Japanese word i.e. Harbour Wave. It is also called Tidal Wave.
The series of large waves caused by the displacement of the large volume of water due to the earthquake in an ocean or lakes, the volcanic eruption in sea or oceans and many more.
80% of the Tsunami takes place in the Pacific Ocean. Most of the countries like Japan, USA, Hawai, etc are at high risk of Tsunami. Landlocked countries like Nepal, Mali, Hungary, Bhutan, Ethiopia, etc are risk-free.
Generally, the earthquake up to 7.5 magnitude doesn’t cause a tsunami. The earthquake of 7.5 magnitudes or more is the greatest reason for the tsunami.
It is also another indirect/ Secondary effect of an earthquake. The earthquake may lead to breaking down of electrical supply, gas pipelines, etc that causes a fire. Once the fire starts, it is very hard to control it from spreading.
In 1906, during the San Francisco earthquake; more people die due to the effect of fire rather than other effects of an earthquake.