Magnitude of Earthquakes

The intensity of an earthquake is assessed on the Rickter Scale, which was developed by geophysicist Charles Richter in 1935. This scale assigns a number to an earthquake based on the severity of the ground motion It ranges from 0 to 8+. It is logarithmic so that an earthquake with a magnitude 4 causes 10 times as much ground motion as an earthquake of magnitude 3. Similarly, an earthquake of magnitude 4 causes 100 times much ground motion as an earthquake of 2 magnitudes shakes the ground.

Magnitude of an Earthquake: It is the most common measurement of an earthquake’s size. It is a measurement of the size of the earthquake source and is the same number no matter where you are or what the shaking feels like. These days, the Richter Scale has become an outdated device for measuring the magnitude of an earthquake. The Richter Scale is no longer being used by the United States Geological Survey for large, and teleseismic earthquakes. The Richter scale measures the largest wiggle (amplitude) on the recording, but other magnitude scales measure different parts of the earthquake. The United States Geological Survey currently reports earthquake magnitudes using the Moment Magnitude scale, though many other magnitudes are calculated for research and comparison purposes.

Intensity of an Earthquake: The value of the intensity of an earthquake changes from location to location. Intensity of the earthquake is a measurement of shaking and destruction caused by an earthquake. Earthquake size can be judged through its intensity which reflects its impact on the structures, people, and their activities. Intensity of an earthquake is measured on Mercalli Scale which was developed in 1905 by Italian geologist Giuseppe Merealli. Later on, it was modified in 1931. This scale assigns a number to an earthquake ranging from I to XII Roman numbers. For example, an earthquake of intensity I is negligible and can be detected by instruments only. Similarly, an earthquake of intensity II is also feeble, an earthquake of the intensity of III is slight, IX is ruinous. X is disastrous. XI is very disastrous, and an earthquake of intensity XII is catastrophic.


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