Tsunami Buoys: A Key Link in Warning System to Prevent Deadly Disasters
Almost 1,000 kilometres off the Thai coast devastated by a tsunami 20 years ago, engineers lower a detection buoy into the waves – a key link in a warning system intended to ensure no disaster is as deadly again.
The 2004 Tsunami: A Devastating Event
On December 26, 2004, a magnitude 9.1 earthquake under the Indian Ocean triggered a huge tsunami with waves up to 30 metres (100 feet) high. Only a rudimentary warning system was in place at the time, with no way to alert the millions of people living around the Indian Ocean in advance. More than 225,000 people were killed in a dozen countries.
Global Tsunami Information System
In the years following the disaster, multiple governments developed a global tsunami information system, building on the US National Oceanic and Atmospheric Administration’s (NOAA) network of six detection buoys in the Pacific. Known as Deep-Ocean Assessment and Reporting of Tsunamis (DART), the system now has 74 buoys around the world.
How the Buoys Work
Each buoy floats on the surface while tethered to the seabed, monitoring signals from a seismic sensor on the ocean floor and changes in the water level. Installed in some of the toughest working environments anywhere on the planet, the battery-powered buoys must be replaced every two years. Only 50 of the devices are currently operational, but the network has been designed to provide coverage regardless.
Five-Minute Warning
The same team also sought to replace a closer buoy in the Andaman Sea, 340 kilometres from the coast, but were unsuccessful and will mount a new mission in the coming weeks. Shawn Stoeckley, a mechanical engineer from buoy manufacturers Science Applications International Corporation (SAIC), calibrates the system from his laptop on board before it is deployed. "I feel that it has a lot of purpose, that it can save coastal lives," he said.
Thailand’s Tsunami Warning System
Thailand’s two DART buoys are linked by satellite to a nationwide network of 130 alarm towers equipped with sirens and loudspeakers that can broadcast in five languages in coastal provinces. Residents in disaster-prone areas also receive an SMS alert of an imminent tsunami, warning them to evacuate quickly. Before 2004, it would take anywhere from 15 to 50 minutes before an alarm could be issued, says Laura Kong, director of Uncesco’s International Tsunami Information Center. "Today it’s typical we would get something within five to seven minutes," she said.
False Alarms and Mobile Phones
Mobile phones have become ubiquitous and disaster apps widely available in the years since the tsunami, but locals say the towers are still vital. Songsil Nodharith, 51, head of Khuek Khak village, helped residents to evacuate "without even grabbing their belongings" during a night-time false alarm last year and urged authorities to ensure that the towers were well maintained.
Conclusion
The 2004 tsunami was a devastating event that claimed the lives of over 225,000 people in a dozen countries. While the threat of another tsunami on the same scale is still present, the global tsunami information system and warning systems in place can provide critical minutes of warning, potentially saving thousands of lives. As UN experts say, there is a "100% chance" of another tsunami on the scale of 2004 at some point, and it is crucial that we continue to work towards improving our warning systems to mitigate the impact of such disasters.
Frequently Asked Questions
Q: How many buoys are currently operational in the global tsunami information system?
A: Only 50 of the 74 buoys are currently operational.
Q: How often do the buoys need to be replaced?
A: The buoys must be replaced every two years.
Q: What is the typical warning time for a tsunami in Thailand?
A: It would typically take around five to seven minutes to receive a warning.
Q: How many people were killed in the 2004 tsunami in Thailand?
A: Over 5,000 people were killed in Thailand, with 3,000 missing.