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. Ten observatories in peninsular India were upgraded in 1996-97. A National Seismological Database Centre and a Central Receiving Station have been established in New Delhi to receive, archive and analyse seismic data.