Japanese quake and tsunami

So, in news just in, an 8.9 quake hit near Japan an hour ago, sending a 4m tsunami crashing into large parts of the coast.

The richter scale is of course difficult for most people, as effects of an earthquake can be compounded and are related to depth (hence so much damage from a "small" quake in Christchurch), and secondly as it is not linearly scaled. To give an idea, this earthquake in Japan is roughly equivilent to 238,000,000 tonnes of TNT, whereas the 6.3 Christchurch quake is equivilent to 42,300 tonnes of TNT.

In any case, I hope the Japanese are OK, and hope that any rescues are not hampered by so many Japanese rescuers being here in New Zealand.

Sendai Earthquake, Japan, 11 March 2011

http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc0001xgp.php