Fukushima's tsunami was warned in 2001

While there was no historical precedent for a 9.0 earthquake in Tōhoku, there is at least this scientific warning showing that a large tsunami like 2 weeks ago was expectable near Sendai: 
"The recurrence interval for a large-scale tsunami is 800 to 1100years. More than 1100 years have passed since the Jogan tsunami and, given the reccurrence interval, the possibility of a large tsunami striking the Sendai plain is high. Our numerical findings indicate that a tsunami similar to the Jogan one would inundate the present coastal plain for about 2.5 to 3 km inland."
[Source: Minoura et el., 2001, Journal of Natural Disaster Science, 23, 83-88. Academic article pdf here]
The Fukushima Nuclear plant is only a few tens of meters away from the ocean, and it was build within the area where these past tsunamis were described, as I show in this image modified from the original paper.
By the way, it is amazing how well this forecast published in that article in 2001 fits the tidal measurements obtained during the tsunami.

The earthquake in Tohoku-Oki earthquake in Sendai inflicted relative little damage through seismic waves (probably due to the good architecture practices) in comparison to the huge looses produced by the tsunami, including the ongoing nuclear unrest in Fukushima.

[interesting update on the Tohoku-Oki earthquake]