15 Sep : Based on magnitude, earthquakes may be classified as microearthquakes, slight-, moderate-, great- and very great as detailed below:
Microearthquake -less than 3.0
Slight – 3.2-4.9
Very great – Greater than 8.0
Depending upon the epicentral distance of the earthquake, they may also be classified as local shock, near shock, distant shock and teleseismic shock as detailed below:
Epicentral Distance in degress
Local shock Less than 4.0
Near shock Between 4.0 and 10.0
Distant shock Between 10.0 and 20.0
Teleseismic shock Greater than 20.0.
For the Earth as a whole, the frequency of occurrence of earthquakes in different magnitude is given below:
Magnitude (Ms) Average number of earthquakes/year
A list of damaging earthquakes in India during the last about ten years:
- Uttarkashi earthquake of October 20,1991 (M:6.6).
- Latur earthquake of September 30,1993 (M:6.3).
- Jabalpur earthquake of may 22,1997 (M:6.0).
- Chamoli earthquake of March 29,1999 (M:6.8).
- Bhuj earthquake of January 26,2001 (M:6.9).