Japan's guidelines to help tsunami-prone nations

Japan's guidelines to guard against future disasters is an important reference point for other tsunami-prone nations, suggests a study.

Before 2011, Japan was considered to be the best prepared nation on the earth to withstand a large tsunami on its coasts.

However, the size of the waves generated by the earthquake in Japan in March 2011 led to sea defences and other coastal structures being overwhelmed.

Since then, new engineering guidelines have been drawn up transforming Japan's coastal defences.

The study, led by Alison Raby, associate professor in the School of Marine Science and Engineering at Britain's Plymouth University, said other nations in known tsunami risk areas need to follow these guidelines to keep their coastlines safe in the future.

"After the 2004 tsunami in the Indian Ocean, the non-structural measures already in place in Japan were quite effective and meant that tsunami casualty figures -- although exceeding 18,000 -- were relatively low in comparison to the levels of devastation caused and the population living in the inundated areas," Raby said.

"After 2011 event Japan revised its design codes for sea defence structures in an effort to limit inundation extent and devastation from future events," he said.

"It is essential that Japan's new sea defence plans are disseminated as widely as possible, both to inform industrialised nations and those that rely on international codes," he added.

The research, funded by Britain's Engineering and Physical Sciences Research Council, enabled Raby and other scientists to analyse the disaster scenario manually prepared by Japan's National Institute for Land and Infrastructure Management and also compared it with its European and US equivalents.

"This is understandable in some regions where less developed countries face competing pressures for limited financial resources, but it is notable that this threat is not addressed in design codes for at-risk European countries," the study said.

The research findings were published in the latest issue of International Journal of Disaster Risk Reduction.