"The local community design in crucial" when it comes to responding to the consequences of tsunamis, Yoshiyuki Kawazoe, an industrial science professor at Tokyo University, told a seminar at the World Water Week conference in Stockholm.

On March 11 this year, as large swaths of northeastern Japan were being devastated by giant earthquakes and tsunamis, the village of Yoshihama was spared, suffering not a single death, largely thanks to local urban planning, he said.

In Yoshihama, "the residence areas were built outside of flooding areas. The local land use planning made it so that no one was living behind the tide embankment," Kawazoe explained, pointing out that people there had decided "they could accept damages to the rice fields but not to the residence areas".

Lessons should be learned from Yoshiyuki, he said, insisting "we need to rethink engineering after this specific disaster".

It should be "up to the local communities to decide how big future tide embankments have to be built," he said, pointing out that "the higher an embankment is the more expensive it is", so it should be "a question for the community to decide".

Makoto Taniguchi, a scientist at the Research Institute for Humanity and Nature (RIHN) in Kyoto, also stressed the importance of involving the local community in tsunami preparedness.

At a national level, "we need to better share and learn from the local knowledge and experiences", he told the Stockholm conference.

A study conducted by RIHN after this year's tsunami disaster concluded that "preventing tsunamis requires huge investments which is not economically and socially feasible".

It is therefore important to "know the historical and cultural contexts and practices of livelihood in local communities and consider future options available with the communities," the study said, stressing that "society and households need to have a capacity to rebuild livelihood as quickly as possible".

Japan, located at the junction of four tectonic plates, experiences 20 percent of the strongest quakes recorded on Earth each year.

On March 11, a 9.0-magnitude earthquake set off a giant tsunami, leaving more than 20,000 people dead or missing and creating the world's worst nuclear disaster in 25 years at the Fukushima plant.

Maehara, once dubbed "Japan's Tony Blair" for his telegenic charm and ease before the cameras, is from the conservative wing of the ruling party and known for his strong stance towards China and North Korea.

At age 49, Maehara would become Japan's youngest post-war prime minister if he were to win the party presidency in a vote scheduled for next Monday, to be followed by parliament's confirming the new premier Tuesday.

Maehara's announcement pits him against the favourite so far, Finance Minister Yoshihiko Noda, in the contest for the leadership of the Democratic Party of Japan (DPJ).

A recent Kyodo News survey showed Maehara was the most popular candidate, with public support of 28 percent against Noda's 4.8 percent.

Others in the race are Farm Minister Michihiko Kano, Trade Minister Banri Kaieda and former transport minister Sumio Mabuchi.

Maehara said the ruling party must "unite as one" to solve the crisis brought on by the March 11 massive earthquake and tsunami which sparked an emergency at the Fukushima Daiichi nuclear power plant.

"Please allow me to stand at the helm of our efforts to overcome the national crisis with the help of every single one of you," Maehara told a meeting of political supporters, watched by the media.

Maehara said economic growth and containing the nuclear crisis are key issues for the next leader.

"We must pursue politics that live up to the people's expectations and give them a sense of security and hope," he said.

Maehara's profile rose last year when he was at the forefront of a bitter territorial dispute with Asian rival China that went on for months and plunged Beijing-Tokyo relations to their lowest point in years.

He is also known for his strong stance on communist North Korea, which has faced pressure from Japan over its nuclear and missile programmes and past kidnappings of Japanese nationals.

But Maehara's stint as foreign minister abruptly ended in March, days before the earthquake, tsunami and nuclear disaster hit Japan.

He stepped down after admitting he had received around 250,000 yen ($3,000) from an ethnic Korean who is not a citizen -- a family friend who runs a restaurant -- in contravention of Japanese political funding laws.

Still a lawmaker, he has kept a relatively low profile in the five months since the March 11 disaster, a time in which Prime Minister Naoto Kan, 64, has come under fire for his emergency management.

Kan has promised to step down provided that two key bills, on bonds issuance and on promoting renewable energy, are passed this week. Kan said Tuesday he expected his successor to be appointed on August 30.

The centre-left DPJ swept to power in a landslide election two years ago, ending more than half a century of almost unbroken conservative rule, but its term since then has been troubled.

The party has been internally split, and a key question ahead of Monday's vote will be who will win the backing of scandal-tainted but powerful faction boss Ichiro Ozawa.

The premier chosen next week will be Japan's sixth new leader in five years.