Japan needs better tsunami infrastructure: Expert

More infrastructure spending by Japan could have lessened the impact of this month's deadly tsunami but the government has become too reliant on low-cost measures such as handing out warning maps, a prominent tsunami researcher said.

Japan should invoke Western-style urban planning to keep houses and hospitals further from the coast as it rebuilds from the crippling disaster, said Fumihiko Imamura, a professor at Tohoku University's Disaster Control Research Centre.

Japan's cash-strapped government has moved away in recent years from costly projects such as increasing the height of sea walls to budget measures like producing maps that show which areas are at lower sea levels, he said.

"We cooperate with the government on tsunami countermeasures, but there has been less financing and sometimes there isn't enough for the construction of structural measures," Imamura said in an interview on Sunday.

"Now, the government's focus has shifted to non-structural measures, because they are cheaper."

Imamura, a scientist who has been studying tsunami for nearly 30 years, uses computer models based on historical data to predict the speed and size of the deadly waves caused by earthquakes.

The tsunami that savaged Japan's northeast coast on March 11 was one of the largest in recorded history and far bigger than anything anticipated by scientists because they did not expect such a massive earthquake, he said.

The disaster killed more than 10,000 in the world's third-biggest economy and nearly 17,500 are missing.

The waves were so big that they destroyed several of the tidal gauges used to measure wave size. The tsunami itself lasted as long as two days, as its waves reached as far as Chile before being reflected back to Japan, he said.

As one of the world's most earthquake-prone countries, Japan is at the forefront of developing measures to lessen the impact of the waves, but more needs to be done.

The government should plant more pine and mangrove trees along the coast to slow down a tsunami, and build more evacuation centres that can withstand the waves, Imamura said.

He also believes that Japan should better plan for disasters when rebuilding ravaged towns.

One of the world's most densely populated countries, even Japan's rural towns and villages often seem cramped, with a handful of houses crimped together near the coast.

"We are living very close to the coast. The fishing industry needs to be near the coast, but living areas and other facilities need to be farther in," Imamura said.