The main reason for the incidence seems to be the fact that the (General Electric type system) emergence generators got their fuel from tanks that were located on the ground? The tsunami that hit one hour after the earthquake washed all the fuel tanks away. That inhibited the generators to run and the emergency cooling systems stopped (this is my version of the reason).
What ever the reason was the huge tsunami and not the earthquake. It is also possible that the water and wave destroyed some sensitive control systems around the emergency generators?
It is interesting to see the final report of the disaster.
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The Fukushima Daiichi Nuclear Disaster (福島第一原子力発電所事故) was a nuclear disaster that affected the...