The Richter Scale

Can one measure the exact extent of devastation caused by a major earthquake? Perhaps not. But the reason for it can be measured. When the Nepal earthquake struck on 25 April, it measured 7.9 on the Richter Scale—which is quite a high number and explains the way buildings crumbled there.

Developed by Charles F Richter, the Richter Scale is used to rate the magnitude of an earthquake by the amount of energy it releases. This, in turn, is calculated using information gathered by a seismograph. Magnitudes are based on a logarithmic scale, with a base of 10. In simple terms, for each whole number that you go up on the magnitude scale, the amplitude recorded by a seismograph goes up ten times. Thus, a magnitude 5 earthquake would result in ten times the ground-shaking as one that measures 4 on the Richter Scale.

However, the Richter scale only offers an approximate idea of an earthquake's impact. A lot depends on the geographical location of the place, the way its man-made structures are built, the distance from the epicentre, and the type of surface material (rock or sand) the buildings rest on. So, there could be places that might not be affected by a quake measuring 7 on the Richter Scale, and there could be places that are reduced to rubble with one measuring just about 6. Also, the further you are from the epicentre, the less damage you see.

'Earthquake resistant' is a term that's used as a catchphrase. However, what builders need to focus on, instead, is how to make buildings earthquake proof. This means that buildings should be constructed in such a way that they're flexible, letting these structures sway horizontally (like leaves of grass), thus absorbing the shockwaves from an earthquake.