Earthquake Radiated Energy as a Function of Magnitude

Magnitude

Amount of TNT to Produce Waves Similar to this Magnitude*

Radiated Energy in Joules

Notes
-3.0 0.001 ounces 0.200E+01 1.5 foot-pounds (18 inch-pounds)
-2.0 0.032 ounces 0.631E+02 47 foot-pounds
-1.0 1.0 ounces 0.200E+04 1,500 foot-pounds
0.0 32 ounces 0.631E+05  
1.0 63 pounds 0.200E+07  
2.0 1 ton 0.631E+08 Only felt nearby.
3.0 32 tons 0.200E+10  
4.0 1 kton 0.631E+11 Often felt up to 10's of miles away.
5.0 32 ktons 0.200E+13  
6.0 1,000 ktons 0.631E+14  
6.9 22,500 ktons 0.141E+16 1995 Kobe, Japan, Earthquake
7.0 32,000 ktons 0.200E+16  
8.0 1,000 mtons 0.631E+17  
9.0 32,000 mtons 0.200E+19  
9.2 64,000 mtons 0.398E+19 1964 Alaska Earthquake - Second largest instrumentally recorded earthquake
9.5 180,000 mtons 0.112E+20 1960 Chile - Largest instrumentally recorded earthquake

*This is the amount of TNT that would be required to generate ground shaking similar to an earthquake of each magnitude.  This is based on the observation that a 1 kton explosion is approximately equivalent to a magnitude 4 earthquake.

More details on the calculation of these numbers may be found here.

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