The entire planet vibrated on December 26, 2004, as an earthquake erupted in the Indian Ocean. The destruction — 1.6 million people displaced, another 230,000 swallowed by waves as high as 30 meters, and $14 billion lost — left the world a different place.

“It was an incredible shock. The countries in the region had no idea they were vulnerable to this kind of hazard,” says Tony Elliott of the Intergovernmental Oceanographic Commission. As the body for marine science within the United Nations, the commission received a mandate from the international community to coordinate a tsunami alert system.

No one had received a warning that a tsunami was approaching. In some places, more people flocked to the shores to watch with wonder as the waters receded, only to be taken when the giant waves rolled in.

A street in Phuket, Thailand, moments after the Indian Ocean tsunami came through in 2004 (© AP Images)

At the time, only the Pacific had alert systems to detect tsunamis. The rim of the Pacific is called the Ring of Fire for its earthquakes and volcanoes, and tsunamis are common. (Even asteroids can trigger tsunamis. Read about NASA’s asteroid alert system.)

After the 2004 tsunami, humanitarian aid poured in from all over the world. There were search-and-rescue operations, emergency food-assistance programs, shelter provisions, psychological support, and anti-trafficking and cleanup activities provided by the U.S. government alone. Within five days, the international community pledged more than half-a-billion dollars in support and about $6 billion more has been donated.

In the wake of the disaster, “there was high awareness at the level of decision-makers, and there was no more important issue than putting in place a warning system for the Indian Ocean,” says an Intergovernmental Oceanographic Commission program specialist, Bernardo Aliaga.

Building the system

(Sony Budi Sasono)

In 2005, an interim service to monitor the Indian Ocean was set up by the Pacific warning center and Japan’s meteorological agency.  Countries in the region also began developing their own warning centers. The Indian Ocean Tsunami Warning and Mitigation System became fully operational in 2011.

Each of its 28 member countries monitor for threats of tsunamis. The system has been put to use 10 times. According to researcher Thomas J. Teisberg, the Indian Ocean tsunami warning system may save at least 1,000 lives each year.

In response to the 2004 tragedy, alert systems also sprang up in the Mediterranean and the Caribbean. A total of 147 countries participate in the Tsunami Programme — seismologists, oceanographers and emergency managers working around the clock every day with the common purpose of saving lives.

They use seismic sensors to detect earthquakes, as well as deep-ocean and coastal gauges to monitor the generation and spread of tsunami waves. Within 10 minutes, real-time data are available at regional and national warning centers.

(Escuela de Ciencias del Mar de la Pontificia Universidad Católica de Valparaíso)

“Bells start ringing in warning centers and beepers go off for operators in centers,” Aliaga says. People in threatened communities have anywhere between 30 minutes and 14 hours to find higher ground or evacuate.

A sea of calm ahead?

Although large tsunamis are rare, danger lies in letting them fade from memory. To maintain awareness of this threat, the commission conducts drills and exercises every two years. Countries bordering the Black Sea, including Romania and Russia, participated in a recent exercise for the first time.

“The Indian Ocean is certainly a lot safer than it was in 2004, but we can never be completely safe,” Elliott says. “What we have to be is ready.”