Buildings can be created to withstand the most powerful earthquakes, but designers remain largely powerless in thwarting the destructive forces of a tsunami, such as the one that slammed Japan's northeast coast Friday. A group of engineers hopes to change that.
University of Ottawa associate professor Ioan Nistor, who specializes in coastal engineering, is part of a new committee with the American Society of Civil Engineers that will examine how to create tsunami-resistant buildings. The group begins its work in July.
While measures for dealing with quakes are entrenched in the building codes of many countries, Dr. Nistor notes that no clear guidelines exist for developing houses, factories and office towers that can weather tsunamis.
"Even if a building can withstand an earthquake, there's no guarantee it can withstand a tsunami," he said.
The death toll and damage in Japan is still being assessed, but it's clear the tsunami that arose from Friday's 9.0-magnitude earthquake devastated the country's northeastern coast.
Towering as tall as 10 metres, the tsunami overpowered the country's seawall defences, engulfing houses, cars and possibly thousands of people. John Clague, director of Simon Fraser University's Centre for Natural Hazard Research, estimates many residents had only 15 to 25 minutes to flee to higher ground after the earthquake struck.
Still, Dr. Clague suspects Japan's tsunami and earthquake preparedness, which includes evacuation drills, escape routes and towering shelters, prevented countless deaths.
"It could have been far worse," he said. "They are far better prepared then we would be on our [West]Coast."
Japan has the most advanced tsunami-warning system in the world. Tsunami advisories are a common occurrence in the country.
For instance, two days before the gigantic quake ruptured the sea floor about 130 kilometres east of the Japanese city of Sendai, a caution was issued for a smaller stretch of the northeastern coast. In that case, waves were only expected to reach heights of half a metre.
Once triggered, tsunamis cannot be stopped.
Tsunamis (Japanese for harbour wave) are a series of waves created by an abrupt disturbance in the sea floor. Generally, the trigger is an earthquake.
The sudden movement of continental plates can displace a huge volume of water and have catastrophic results for coastal communities.
A tsunami may be barely detectable at first, rising only a few centimetres in deep ocean. However, as it races toward shore, it can gain tremendous energy and morph into a fast-moving wall of water that stretches several metres above sea level. The speed of last week's tsunami has been compared to that of a jumbo jet.
"Even though a warning was issued, you need time to evacuate people," Dr. Nistor said. "There was very limited time."
At the moment, concrete seawalls - which cost billions of dollars to build - are one of the main tools used to buffer communities from tsunamis. Dr. Nistor hopes the creation of tsunami-resistant buildings will one day provide another line of protection.
He and several colleagues from the University of Ottawa did some preliminary work on the matter after a tsunami devastated Indonesia in 2004. They note the force of the waves on a building can be greater than an earthquake's impact.Report Typo/Error