http://en.wikipedia.org/wiki/Richter_magnitudeRichter Magnitude Approximate TNT for Seismic Energy Yield Example
-1.5 ........................ 6 lb .......................................................Grenade
1.0 ..........................30 lb ......................................................Construction site blast
1.5 ..........................320 lb ....................................................WWII conventional bombs
2.0 ..........................1 ton..................................................... WWII conventional bombs
2.5 ..........................4.6 ton ................................................."Cookie" blockbuster bomb (WWII)
3.0 ..........................29 ton ..................................................MOAB bomb blast, 2003
3.5 ...........................73 ton .................................................Chelyabinsk nuclear accident, 1957
4.0 ...........................1 kiloton ..............................................Small atomic bomb
4.5 ...........................5.1 kiloton ...........................................Average tornado (total energy)
5.0 ............................32 kiloton ............................................Nagasaki atomic bomb
5.5 .............................80 kiloton ..........................................Little Skull Mtn., NV Quake, 1992
6.0 .............................1 megaton ........................................Double Spring Flat, NV Quake, 1994
6.5 .............................5 megaton ........................................Northridge quake, 1994
7.0 ...........................32 megaton ........................................Largest thermonuclear weapon
7.5 ............................160 megaton ......................................Landers, CA Quake, 1992
8.0 .............................1 gigaton ...........................................San Francisco, CA Quake, 1906
8.5 .............................5 gigaton ...........................................Anchorage, AK Quake, 1964
9.0 ...........................32 gigaton ............................................Indian Ocean quake/tsunami, 2004
10.0 ...........................1 teraton ............................................San-Andreas type fault circling Earth