-Japan has a very effective warning system for earthquakes, and the infrastructure actually withstood the earthquake itself well.
But with a magnitude 9 earthquake there will be a big wave, off the coast of Japan the earth's crust moved maybe fifty meters along the fault on the plate boundary, there will be enormous amounts of water that will lift.
Says Björn Lund, senior lecturer in seismology at Uppsala University.
-The nuclear power plants survived the strong earthquake, even though the plant lost power from the external grid, the backup systems for reserve power worked.
But when the wave washed in with an enormous amount of water, diesel tanks were knocked away and all electronics were submerged.
When the plant becomes without electricity, there are few opportunities to cool the hearth.
There were ramparts to protect against tsunamis, but they were far too small.
Says Jan Hanberg at the Swedish Radiation Safety Authority.
Seismologist Björn Lund and nuclear expert Jan Hanberg look back 10 years and remember the days when the phone never stopped ringing and it was all about a huge tsunami.
Watch Björn Lund and Jan Hanberg talk about the natural disaster in the clip above