The Boxing Day tsunami off the Indonesian coast of Sumatra on Dec. 26, 2004 was one of the world’s worst disasters.
A magnitude 9.1 earthquake had unzipped a 1,300-kilometre subduction zone, heaving the sea floor and generating killer waves that took almost a quarter of a million lives in 14 countries.
Scientists knew the quake had occurred – it was picked up on seismographs half a world away – and suspected a tsunami was racing across the Indian Ocean. But there was no effective way to warn communities so people could head to higher ground, even though in some regions it took hours for the giant waves to arrive.
“They couldn’t find anyone to give the warning to,” recalls Garry Rogers, a senior seismologist with Natural Resources Canada.
That changed in the aftermath of the disaster, says Rogers, who studies quakes and is Canada’s representative on the international committee coordinating the Pacific tsunami warning system.
“Today virtually the whole world has tsunami warnings in some sense and people to receive those warnings,” says Rogers, who describes the improvements in global tsunami warnings as the “biggest legacy” of 2004 disaster.
After the wrenching images and videos of the tsunami’s toll were seared into the global consciousness, he says things started happening.
“For the first time virtually everybody in the world knew what the hell a tsunami was, including politicians who make decisions,” Rogers said in a recent interview. “Whereas before it was a bunch of scientists like myself saying: ‘You know, we ought to do something because it can be a problem.’”
Millions of dollars have been spent on the new warning system in the Indian Ocean. And there is also a much-expanded system covering the Pacific, Atlantic and Arctic oceans as well as the Caribbean and Mediterranean seas.
Alerts are issued within minutes of a quake that is deemed capable of causing tsunamis and updated as data flows in from tide gauges and buoys strategically placed in the world’s oceans.
“Everyone co-operates and exchanges data,” says Rogers.
The Indian Ocean warning system has 101 sea-level gauges, 148 seismometers and nine buoys, and a sophisticated alert system. But it is not without problems and there are concerns warnings may not always get to people in at-risk coastal communities.
“Some of the people, officials, are not getting the alert,” Ajay Kumar, an official at the Indian National Centre for Ocean Information Services recently told Reuters.
And tsunami drills have revealed “the last mile connectivity is still missing,” Kumar said. “If (a) tsunami is coming, even now people don’t know what is to be done, where to move.”
Rogers agrees there is work to do.
“There is still a big learning curve in terms of what to do with the warnings,” he says, “but the system is vastly improved since 2004.”
Novel initiatives have been used in some places. Cellphones were supplied to all religious leaders and school headmasters on the South Pacific island of Samoa so they could be automatically alerted and pass on warnings in their communities. When Samoa was hit by a tsunami in 2009, the cellphone network was credited with saving many lives, Rogers says.
There are, however, limits to what technology and warning systems can accomplish.
Tsunami warning systems are meant to alert communities giant waves are on the way when earthquakes are too far away to be felt.
But Rogers says people should not wait around for a text message or whistle to blow when they have felt the earth shake violently and are beside the ocean.
The earthquake should be taken as the tsunami warning, he says, and people need to know to head for higher ground quickly.
“That’s really public education rather than horns and bells,” says Rogers, emphasizing public education “is probably as important, or more important, than sophisticated warning systems for locally generated tsunamis.”