Richter Scale on an Earthquake dayAfter Chile’s Calbuco volcano eruption, it was an earthq

Richter Scale on an Earthquake dayAfter Chile’s Calbuco volcano eruption, it was an earthquake in South Asia. Saturday at 11:56 a.m. local time (0611 GMT) cities in the North-eastern region of India and the country of Nepal shook with tremors from an earthquake that measured 7.9 in magnitude. The epicentre was in Nepal’s Kathmandu Valley, near it’s capital (Kathmandu city) close to the Indian border. The earthquake was already covered in an earlier post (link: x). The tremors were so powerful that sitting in the premises of *Kolkata High Court, we were thrown off balance.The original attempt to characterize the intensity of an earthquake based on properties that could be measured during a quake was developed by Charles Richter and Beno Gutenberg, two seismologists from California Institute of Technology, in the year 1935. The Richter magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs - basically how much shaking is measured at a certain point on a seismogram. An earthquake of magnitude 5.0 shows a shaking with 10 times the intensity of a magnitude 4.0, according to the Richter scale, currently known as Local Magnitude (LM) scale.The scale was designed for measuring shallow earthquakes like those in California which occur within 16 kms of the earth’s crust. However, the worldwide study of earthquakes show that the focal depth of a quake may range from 0 to 700 kms. Modern day instruments can accurately determine the intensity of a quake anywhere in the world, so the original Richter scale needed to be refined.The moment magnitude (MW) scale was designed by several scientists at the Caltech in the late 1970s and replaced the Richter scale because it is capable of measuring the impact of an earthquake more accurately. The MW scale uses the ●seismic moment and ◆energy radiated by the quake to determine the total energy released by an earthquake. The MW was adjusted so that it’s values correspond with the values of the more popular Richter scale, but it is incorrect to quote earthquake magnitudes as though they come from the “Richter” scale any more. Today’s quake, a major one, has seen lots of damage and well over 1000 human fatalities reported so far.–RB.Further reading:http://usat.ly/1KeVTWPhttp://bit.ly/1Onzw7ghttp://bit.ly/1bsb6aXhttp://on.doi.gov/1hVppRQImage credit: http://bit.ly/1Dn3356Kolkata to Kathmandu by road on NH 28 is 894 kms.◆ When an earthquake ruptures a fault, the summation of energy flux generated over a broad range of frequencies determine the energy radiated by the quake. It detects the potential of the generated energy to destroy man-made structures.● The varying shapes and directions of motions of waveforms at different distances from the earthquake measures the fault geometry. An estimation of the amplitude of these waveforms is the seismic moment. -- source link

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