London, March 13 (IANS) The total energy released by the megaquake in Japan was about a thousand times the combined energy of all the world's nuclear weapons or 6.7 trillion tons of TNT.
It is a grim reminder of the fact that undersea earthquakes can be so much more devastating than those on the land.
They can generate the most destructive of tsunamis, especially those occurring along substantial linear faults off the coast of Japan.