Competitive Exams: Indian Geography Earthquakes

Indian Earthquakes

  1. The intensity of the earthquake is measured by Modified Mercalli (MM) Scale which is expressed in Roman numerals from I to XII (I Feeble, XII Catastrophic). Based on intensities of the earthquakes recorded on MM Scale, the Indian Standards Institute has divided India into 5 Seismic Zones: Zone I: Intensity V or below (Feeble) Zone II: Intensity VI (Strong) Zone III: Intensity VII (Very Strong) Zone IV: Intensity VIII (Destructive) Zone V: Intensity IX or above (Catastrophic)

  2. Another popular scale is Richter scale. It has 9 divisions starting from 1 to 9 with feeblest at magnitude of 3.5 and most catastrophic known at a maximum of 8.9.

  3. According to seismological studies, about ⅔ rd of India is earthquake prone.

  4. The whole country is divided into three Seismological Zones: Himalayan Zone. Most prone (J and K, HP, Uttaranchal, Nepal Bihar Border, Bihar, North Eastern States). This zone is seismic due to plate tectonics. Himalayas have not yet attained isostatic equilibrium and are still rising. Indo Gangetic Zone. To the south of the Himalayan zone. Most earthquakes in this zone lie in 6 6.5 on Richter scale. This zone is called the zone of comparative intensity and it is more harmful because of high population density. Peninsular Zone Stable mass. It is the zone of minimum intensity.

  5. Other isolated regions including reservoir induced seismicity e. g. Koyna, Idduki.