On the day after Christmas in 2004, a massive undersea earthquake occurs just off the coast of Indonesia at a few minutes before 8 a.m. local time. With a magnitude of 9.3, the quake was the most powerful of the last 40 years and the second largest earthquake in recorded history. It set off a deadly tsunami that, in the final estimate, killed an estimated 230,000 people and wreaked untold devastation on a wide swath of coastline from Somalia on the east African coast to Sumatra in Southeast Asia.
While most earthquakes last for only a few seconds, it is reported that the Sumatra-Andaman earthquake, as it is known to the scientific community, lasted almost ten minutes, triggering other earthquakes as far away as Alaska and causing the entire planet to move at least a few centimeters. The epicenter of the earthquake was 100 miles west of Sumatra, at the western end of the area known as the “Ring of Fire” for its intense seismic activity. That region has been home to more than 80 percent of the world’s largest earthquakes. Since 1900, when accurate measurements began to be made, only three or four earthquakes have rivaled the Sumatra-Andaman in power.
It is estimated that the quake caused the sea bed of the Indian Ocean to rise almost 10 feet, causing seven cubic miles of water to be displaced. The resulting tsunami (from the Japanese words for “harbor” and “waves”) sent waves of up to 100 feet crashing into the shores of the Indian Ocean, hitting Somalia, Indonesia, Sumatra, Sri Lanka, southern India, and Thailand, and flooding a series of islands, including the Maldives. In deep water, tsunami waves are barely noticeable and mostly harmless, but in the shallow water near coastlines, tsunamis slow down and form large destructive waves.
Despite scientists reporting the quake about 15 minutes after it struck, there was no tsunami warning system in place in the Indian Ocean with which to track possible tsunamis. A warning system in the Pacific Ocean–where most tsunamis occur–has proven successful in minimizing deaths from tsunamis since it was installed in the mid-1950s. However, the warning systems are difficult and expensive to set up and, despite some requests for aid, one had never been built in the Indian Ocean, located in a relatively poor part of the world.
Within 30 minutes, the tsunami had hit Sumatra and, within two hours, it had battered the coasts of Thailand, Sri Lanka, and southern India. Despite the time lag, the vast majority of victims had no idea that the tsunami was on the way. Although initial news reports severely underestimated the death toll, it became clear within days that the tsunami had created a disaster of unprecedented proportions–killing an estimated 230,000 people and leaving more than a million homeless. Thousands–most likely swept out to sea–will never be found. It has been reported that one third of the victims were children, due to both the region’s demographics and children’s relative inability to protect themselves. The tsunami also killed more women than men, a statistic that is chalked up to the fact that more men may have been working out at sea in deep water, where they were safer. In addition to natives of the region, an estimated 9,000 people from outside the area, mainly Europeans, were killed while on vacation at the region’s resorts.
Although there were no official government warnings of the impending disaster, some communities were able to read nature’s signs and knew to evacuate. On the Indonesian island of Simeulue, the oral tradition of the native islanders contained references to a tsunami that occurred in 1907 and the incidents that preceded it. They recognized the receding tide that followed the earthquake as a sign of a coming tsunami and retreated to higher ground, surviving the massive waves.
Most, however, were not so lucky. Despite substantial relief efforts, with public and private aid to the affected areas totaling in the billions of dollars, it will take decades or longer for the shattered infrastructures and economies of the affected regions to be rebuilt. As part of their response to the disaster, the United Nations is currently planning the implementation of a tsunami warning system for the Indian Ocean. Scientists believe that other large earthquakes are likely in the area of the sea floor near the epicenter of the Sumatra-Andaman quake.