Fukushima was caused by shoddy planning. From a Carnegie Endowment report[1]:
"The original design-basis tsunami for Fukushima Daiichi of 3.1
meters was chosen because a 1960 earthquake off the coast of
Chile created a tsunami of that height on the Fukushima coast."
Assuming that future tsunamis would be no higher than a recent historical tsunami is already silly. But it's worse:
"one compilation of historical tsunamis in and around Japan lists
twelve events since 1498 having a maximum amplitude of more than
10 meters, six of which had a maximum amplitude of over 20 meters."
In 2002 they already knew the seawater pumps were located too low, but took no action:
"Fukushima Daiichi’s design basis tsunami was estimated to have
a maximum height of 3.1 meters above mean sea level. Given this,
TEPCO decided to locate the seawater intake buildings at 4 meters
above sea level and the main plant buildings at the top of a
slope 10 meters about sea level"
"In 2002, on the basis of a new methodology for assessing tsunami
safety developed by the Japan Society of Civil Engineers, TEPCO
voluntarily reevaluated the tsunami hazard and adopted a
revised design-basis tsunami height of 5.7 meters. Yet, NISA
neither updated the licensing documents to reflect this change
nor reviewed TEPCO’s analysis. Given that the revised
design-basis tsunami was now 1.4 meters above the seawater pumps,
such a review should have been conducted."
[1]
http://carnegieendowment.org/files/fukushima.pdf
