Tuesday, August 28, 2012

What is earthquake and how it occurs

Image credit: Flickr digitalsadhu

What is an earthquake:

To a layman, an earthquake is simply a tremor experienced throughout the world, with varying impacts and thereby causing no or mild or substantial loss of lives and/or property.  For others more deeply involved like the scientists who study and undertake research on this violent activity of mother earth (known as seismologists), the earthquakes are the disturbance or movement of Earth’s tectonic plates.  These tectonic plates, which are believed to be almost 100km thick, are pieces of the Earth’s crust and uppermost mantle, also known to many as the lithosphere.

How it occurs:

The movement of the plates or the earthquake results from a sudden release of energy in the earth’s crust creating seismic waves.  This is of course the natural cause of earthquakes.  However, certain human activities like coal mining, oil drilling, construction of large water dams, etc. have also been found to induce seismic activity.  While an earthquake itself may result in a lot of destruction and loss, it may further trigger a tsunami, landslide or even a volcanic activity thereby amplifying the loss/destruction.  The scale of loss/destruction will be directly proportional to the intensity of the earthquakes together with the habitation of the affected region.  Thus, the higher the intensity of the earthquake and the population, more devastating would be the outcome.


The intensity or the magnitude of earthquakes is commonly measured on the local magnitude scale, popularly known as the Richter scale, named after its developer Charles Richter of the California Institute of Technology.  An earthquake of magnitude of up to 2.0 on the Richter Scale is described as `micro’ while that of 10.0 or upwards falls under the category of `massive’.

Largest Recorded Magnitudes:

Image credit: Flickr astanhope
With a magnitude of 9.5 on the moment magnitude scale (which measures the size of earthquakes in terms of the energy released), Chile has the largest recorded earthquake in the year 1960.  In most recent times, Japan recorded a large earthquake of magnitude 9.0 in 2011.  The recorded world’s deadliest recorded earthquake occurred in 1556 in central China with a death toll of approx. 830,000 people.
Whatever the case may be, mankind’s zest for life can be seen in the modern earthquake-resistant architecture and development of numerous other emergency management / preparedness strategies to brave the earthquakes.

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