An earthquake is the shaking of the surface of the Earth, resulting from the sudden release of energy in the earth’s lithosphere that creates seismic waves. Earthquake's point of initial rupture is called its seismic focus or hypocenter.
The epicentre is the point at ground level directly above the hypocenter.
The epicentre is the point where the waves of an earthquake are first observed.
All natural earthquakes occur in the lithosphere.
The magnitude of an earthquake is the indication of the energy Released. The intensity of the earthquake is measured on Richter scale and intensity on Mercalli scale.
Richter scale was invented in the year 1935 by Charles Francis Richter. Richter scale is a logarithmic scale measuring between 1 to 10 where each step represents a ten-fold increase
of amplitude on the seismograph, whereas in terms of energy, each whole number increases corresponds to an increase of about 32 times the amount of energy released.
Every point on the scale (earthquake waves) denotes an energy release, equivalent to 6 ounces of TNT (Trinitrotoluene).
Seismometer is used to measure earthquake waves.
The Ring of fire is a major area in the basin of the Pacific Ocean where many earthquake and volcanic eruptions occur. The Ring of Fire is sometimes called Circum Pacific belt. About 90% of the world’s earthquake occurs along the ring of Fire.
There are four main conditions for the occurrence of earthquake in this region –
(1) Point of interaction between sea and Land
(2) Young Fold mountainous region
(3) Volcanic Activity
(4) Plate tectonics – movement and collision of lithospheric plates.
The region consists of Chile, California, Alaska, Japan, Philippines, New Zealand etc..
The Northwestern part of India-Sub continent is an earthquake prone area. It is because it is the convergence zone of Indo-Eurasian tectonic plates. The earthquake-prone regions of India are included in the Mid-Continental Belt. The Belt starts from Cape Verde and includes Atlantic ocean, Mediterranean sea, and young fold mountain ranges like the Alps, Caucasus and Himalayas.
The Fukushima Daiichi Nuclear disaster was an energy accident at the Fukushima Daiichi Nuclear Power Plant initiated primarily by Tsunami following an earthquake on 11 March
2011. It led to nuclear melt down and the release of radioactivity in the area.
