Japan was warned two years ago that its nuclear power plants were not capable of withstanding powerful earthquakes

We already knew:

• GE was warned about 35 years ago that the design of their reactor wasn't safe in case of earthquake and other extreme events
• 20 years ago, a report published by a U.S. Nuclear Regulatory Commission also confirmed the risks and questioned the fact that Tokyo Electric was trying to address those risks.
  

Well thanks to WikiLeaks we now know that:

March 15 (Telegraph) Japan was warned more than two years ago by the international nuclear watchdog that its nuclear power plants were not capable of withstanding powerful earthquakes, leaked diplomatic cables reveal.

An official from the International Atomic Energy Agency (IAEA) said in December 2008 that safety rules were out of date and strong earthquakes would pose a "serious problem" for nuclear power stations.

The Japanese government pledged to upgrade safety at all of its nuclear plants, but will now face inevitable questions over whether it did enough.

While it responded to the warnings by building an emergency response centre at the Fukushima plant, it was only designed to withstand magnitude 7.0 tremors. Friday's devastating earthquake was a magnitude 9.0 shock.