Poor planning raised Japan tsunami toll: NZ study

This March 12, 2011 file photo shows smokes rising from burning homes in Yamadamachi in Iwate Prefecture, northern Japan a day after a strong earthquake triggered a devastating tsunami. Photo / AP

Poor planning, an ageing population and ill-conceived protection walls contributed to the devastation caused by last year's tsunami in Japan, a University of Canterbury (UC) researcher has found.

Chris Gomez said inadequate engineering and ineffective evacuation plans were some of the reasons 20,000 people perished in the tsunami.

"In villages the main escape roads followed the river, which the tsunami followed as well."

The lecturer said having assembly areas at schools located by the coast, ill-conceived protection walls and an inadequate evacuation plan that did not take into account the ageing population contributed to the disaster.

"Many of the elderly residents drowned in their own houses, being unable to evacuate as planned."

In March last year a magnitude 9.0 under sea earthquake caused a series of tsunami which reached up to 40 metres above sea level on the coast of Miyagi Prefecture.

Mr Gomez plans to outline his study and findings from a visit to Japan after the tragedy at the Australasian Natural Hazards conference, held at UC next week.

More than 720,000 buildings were impacted by the tsunami, with 109,862 buildings demolished, 127,100 buildings partially destroyed and more than 480,270 buildings severely damaged.

Mr Gomez said before the tsunami there was a feeling of over-confidence in the engineered structures to protect coastal cities.

"Schools and evacuation grounds should not be rebuilt on the sea-front. There should be a better approach to natural hazards and have an evolving safety plan."

Mr Gomez visited some of the worst hit areas, Kamaishi and Ofunato, on a research trip last year.

"Almost 18 months after the disaster there, more than 300,000 people still live in temporary shelter."

He said there were a lot of lessons New Zealand needed to learn from the events in Japan if they did not want to be confronted with similar problems.