13 February 2021.
An earthquake of magnitude 6.3 hit Tajikistan on February 12, 2020. The tremors were felt in Delhi-NCR, Haryana, Punjab, Chandigarh and Himachal Pradesh. The seismology department at first gave the epicentre as Amritsar because of software error later confirmed epicentre as Tajikistan.
What is an Earthquake?
- Shaking of the surface of the Earth because of a sudden release of energy in the lithosphere of earth is called as earthquake.
- It results into the formation of seismic waves.
- When the epicentre of the earthquakes is on surface, it results into shaking and displacing the ground.
- If the epicentre is located offshore, it results into the displacement of the seabed causing a tsunami.
Causes of Earthquake.
- Earthquakes are usually caused by rupture of geological faults.
- But it may also be caused due to volcanic activity, landslides, nuclear tests and mine blasts.
Hypocentre or focus
It is the point of initial rupture of an earthquake. In seismology, epicentre is synonym of the focus.
The point on the ground or surface directly above the hypocentre is called epicentre.
Types of Earthquake
- Fault Zones:
- Fault means a sharp breakage in the crustal rock. Through this fault, energy releases.
- As a result, the rocks along the fault starts moving in opposite directions. With time, the blocks get deformed and slide past each other abruptly.
- This in turn causes earthquake.
- Tectonic Earthquakes:
- This is the most common earthquake.
- When a large & thin plate of the Earth’s crust and upper mantle gets stuck while moving past each other, pressure builds up beneath the zone.
- When this pressure is released, earthquakes occur.
- Volcanic Earthquake:
- Special class of tectonic earthquake in the areas of active volcanoes are called as volcanic earthquakes.
- It occurs because of injection or withdrawal of magma beneath the Earth’s surface.
- Human Induced Earthquakes:
Such earthquakes are caused as a result of intense mining activity, explosion of chemical or nuclear devices.