What is an earthquake?
The inner core, outer core, mantle and the crust are the four major layers of earth. The crust and the top of the mantle act as a thin skin on the surface of earth.
Earthquake is a natural disaster that happens when two blocks of the earth suddenly slip past one another. It strikes without any warning causing immense loss of human lives and properties. Hypocenter is the location below earth’s surface where the earthquake starts. The location directly above the hypocenter, on the surface of the earth is called the epicenter of the earthquake.
An earthquake can be divided into foreshocks, the mainshock and the aftershocks. In some cases, the aftershocks can continue in the region for weeks and months after the mainshock.
The ‘skin’ is made up of several pieces called tectonic plates. The edges of the plates are called the plate boundaries. The plate boundaries are made up of several faults and most of the earthquakes occur in this world on these faults, as the tectonic plates slide past one another.
Why does the earth shake during an earthquake?
A lot of energy is released when the moving blocks ultimately overcome the friction between the edges of the faults that are stuck together. The energy radiates in all the directions in the form of seismic waves. When these seismic waves reach the surface of the earth, they shake everything on it causing immense destruction.
How do we record earthquakes?
The earthquake is recorded using an instrument called seismograph. Their recordings are called seismograms. During an earthquake, the distance between the shaking part of the seismograph and the motionless part is recorded.
How do we measure the size of earthquakes?
The size of the earthquake/magnitude is determined using the seismogram recordings on the seismograph. The magnitude of an earthquake is directly related to the size of the fault and the amount of slip on the fault. While a short wiggy line on the seismograph indicates a small earthquake, a long wiggy line indicates a large earthquake.
The standard measurement for an earthquake is the Richter scale. It was developed in 1935 by Charles F.Richter of the California Institute of Technology. Using the information gathered by the seismograph, the Richter scale is used to rate the magnitude of an earthquake.
Earthquakes which register less than 3 on the Richter scale are called microquakes. The largest earthquake in the history of the world happened in Chile in the year 1960. The earthquake recorded 9.5 on the Richter scale, killing over 1,900 people!
An earthquake’s destructive power varies according to the composition of the ground and placement of man-made structures on it. The extent of such damage is measured on the Mercalli scale.
How can we locate an earthquake?
Seismograms help scientists in locating the earthquakes as well. Being able to determine the P wave and the S wave is also vital for locating an earthquake.
Scientists make use of the triangulation method to determine where the earthquake exactly happened. If we draw a circle on a map around three different seismographs, the radius of each circle is the distance from that station to the earthquake. The intersection of the circles is the epicenter of the earthquake.
Can we predict earthquakes?
No, even though scientists have tried to find out several ways for predicting earthquakes, they have never really been successful. We cannot predict earthquakes.
Now the question that needs to be answered is whether humans, animals or weather can help us in predicting earthquakes. But we don’t have any substantial scientific evidence for proving the same.
Earthquakes are natural calamities that can bring about miseries and destruction of unknown proportions. The horrors of the Gujarat earthquake which happened on 26 January 2001 still haunts our memories. The earthquake which recorded a magnitude of 7.7 on the Richter Scale devastated the town of Bhuj. Thousands of people lost their lives and properties.
Let earthquakes never happen!! ..
Read more: Elimination Reaction
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Chile (measured 9.5 on Richter scale)