By Quirin Schiermeier of Nature magazine

After the first full-scale tsunami-warning exercise in the region, Indian Ocean nations say that they are finally ready to take control of a system set up in 2005.

On 12 October, 23 nations around the Indian Ocean were involved in a test of how well they would respond to a tsunami. At 8.05 a.m. local time, the Agency for Meteorology, Climatology and Geophysics in Jakarta issued a bulletin about a hypothetical tsunami -- modelled on the one that hit Sumatra on Boxing Day 2004 and claimed more than 200,000 lives -- to national focal points around the Indian Ocean. The focal points then forwarded the alert, which included information on the mock tsunami's arrival time and wave height, to coastal communities and emergency services.

The Indian Ocean Tsunami Warning and Mitigation System (IOTWMS) -- like its long-established counterpart in the Pacific Ocean region -- is designed to bring together seismic-monitoring measurements, sea-level gauges, computer-model-based threat evaluation and logistics to disseminate and act on timely warnings.

The test -- which included evacuation exercises in India and Malaysia -- passed without major glitches, says Tony Elliott, head of the Intergovernmental Coordination Group for the IOTWMS in Perth, Australia. A full evaluation of the exercise, including identifying possible bottlenecks and weaknesses, is due by the end of next month.

Take control

The US$100-million system has been run by Hawaii and Japan since 2005, and they will continue to run it in parallel with the new Regional Tsunami Service Providers (RTSPs) set up in India, Indonesia and Australia, until the end of 2012. The RTSPs will then take over the responsibility.

But several countries, including Somalia, Djibouti, the United Arab Emirates and South Africa, have not yet set up national focal points. In these places, tsunami warnings might therefore arrive too late, if at all, to save lives, says Hermann Fritz, a tsunami researcher at Georgia Tech Savannah.

Also of concern, Fritz says, is Myanmar. Although the country is connected to the warning system, authorities there are notoriously ineffective in coping with natural disasters -- in May 2008, for example, cyclone Nargis killed some 140,000 people there. No warnings or evacuation orders were issued.

"We have pretty much technically solved the tsunami detection issue, but getting warnings down to the 'last mile' is another story," says Costas Synolakis, director of the Hellenic Centre for Marine Research in Athens. "Public education efforts are still lacking. In many places people don't yet know enough to evacuate, even if timely warnings arrive."

A "nightmare scenario", he says, is a massive tsunami following a powerful but slow-rupturing quake that causes little or no ground shaking, because people often then ignore any warnings.

On 25 October last year, around 500 inhabitants of the Mentawai Islands west of Sumatra were killed, despite timely warnings, in a tsunami triggered by a 'slow' undersea rupture of the Sunda 'megathrust'. Scientists expect the fault to produce another big quake soon.

"The way a warning message is formulated is extremely important," says Synolakis. "You need to use strong and clear language. Tell them 'Evacuate now or you will die'."

To what extent the system would have reduced the death toll from the 2004 tsunami is hard to tell, says Emile Okal, a geophysicist at Northwestern University in Evanston, Illinois.

Elliott acknowledges that the system needs more work. "The IOTWMS is operational, but it is not yet finished," he says. "National stakeholders are by now fairly familiar with the warning procedures. But there's an ongoing need to raise awareness and preparedness on the community level."

"Indonesia and other nations in the region have since made significant efforts and a great deal of awareness has been raised," he says. "But any future tsunami will not be a replica of the 2004 event, and as we have seen in Mentawai, there are many issues that still need to be tackled."

This article is reprinted with permission from Nature magazine. It was first published on October 13, 2011.