Note that the first section of the article is about Fukushima Daini, not Daiichi.
The piece confirms that it was the tsunami that caused the bulk of the crisis, not the earthquake directly.
Official notices of the accidents at the Fukushima nuclear power plants give insight into the challenges faced by power plant engineers in the aftermath of last week's natural disasters.
Eight separate ratings on the International Nuclear Event Scale (INES) have now been logged with the International Atomic Energy Agency by the Japanese government. One covers the effect of the earthquake on Japan's nuclear power plants as a whole, putting it as level 3 - a 'serious incident' - because of the eventual need to declare technical emergencies at Fukushima Daiichi and Daini.
The remainder of the nuclear crisis has its origins specifically in the tsunami that followed. Information accompanying the ratings gives insight into the starting point of the crisis and the technical challenges faced by Tokyo Electric Power Company (Tepco) in the immediate aftermath of the tsunami.
http://www.world-nuclear-news.org/RS_Insight_to_Fukushima_engineering_challenges_1803112.html