Both scales are similar in that the stronger an earthquake, the higher its magnitude. The magnitude is measured on the basis of the ground motion recorded by the instrument, after accounting for standard correction to discount the epicentral distance from the recording station. It is linearly related to the logarithm of the amount of energy released by an earthquake. A logarithmic scale ranging from 1 to 10, used to express the total amount of energy released by an earthquake. In this scale, an increase of 1 represents a 32-fold increase in released energy.
Intensity is one thing, magnitude is something else.
You know, by now, what magnitude is, so we won't go into that. Intensity refers to the rating of the impact of a quake at a particular place. It is determined by studying the affected areas, using a descriptive instrument like the Modified Mercalli Scale. The Indian Meteorological Deparment has 45 national seismological observatories. There are nine observatories for special studies in north India and three mobile observatories in and around Delhi.