2004 tsunami: 17 years on, a look back at one of the deadliest disasters ever

December 26, 2021, marks 17 years since the devastating Indian Ocean earthquake and tsunami of 2004 which struck the coasts of multiple countries in south and Southeast Asia and took a fatal toll on the population there.

Listed among the worst calamities in this part of the world, more than 230,000 people across India, Sri Lanka, Maldives, Thailand, and Indonesia were and the countries sustained billions of dollars' worth of damages to property after the 100-foot tsunami triggered by a magnitude 9.1 earthquake.

The 2004 Indian Ocean Tsunami is also known as the Boxing Day Tsunami or, in the scientific community, the Sumatra-Andaman earthquake. According to a report by CNN, the tremors were so powerful that it was one of those rare instances when the entire planet vibrated and no place on Earth escaped movement.

"Globally, this earthquake was large enough to basically vibrate the whole planet as much as half an inch, or a centimeter," the report quoted an associate professor of geosciences at the Penn State University in the United States. "Everywhere we had instruments, we could see motions."

Here's all you need to know about the 2004 Indian Ocean tsunami on its 17th anniversary:

Where was the epicentre of the earthquake?

The undersea megathrust earthquake, which registered a magnitude of 9.1-9.3, originated from an epicentre off the west coast of northern Sumatra in Indonesia, caused by a rupture along the fault line between the Burma Plate and the Indian Plate.

The earthquake was immediately felt in India, Bangladesh, Myanmar, Sri Lanka, Malaysia, Thailand, and the Maldives. In its aftermath, the tsunami followed and, as a result of the seafloor popping up, the height and intensity of the tsunami waves were greatly increased and it led to the destruction of communities along the surrounding coasts of the Indian Ocean.

Triggered by the undersea earthquake activity offshore, the 100-feet-high tsunami waves laid bare complete annihilation in as many as 14 countries, making it one of the deadliest natural disasters in recorded history.

According to geological estimates, the 2004 earthquake was the third-largest of its type to ever be recorded, and it managed to even trigger aftershocks as far away as in Alaska. The plight of the affected people and countries prompted a worldwide humanitarian response, with donations totalling more than $14 billion.

Indonesia, hit worst by the disaster, was however no stranger to earthquakes, lying between the Pacific Ring of Fire and the Alpide Belt along the south and west. The 2002 Sumatra earthquake is, in fact, believed to have been a foreshock to this main event.
 

Tsunami waves more destructive than WWII nuclear bombs

According to Tad Murty, the vice president of the Tsunami Society, the total energy of the 2004 tsunami waves (the large, destructive waves slowed down near the coast and reached 80-100 feet in height) was equivalent to about five megatons of TNT (21 PJ), which is more than twice the total explosive energy used during all of World War II including the two atomic bombs.

A tsunami researcher and forecaster with the National Oceanic and Atmospheric Administration Center for Tsunami Research, Vasily Titov, also cites the destructive capacity of the 2004 tsunami to the earthquake in the megathrust fault, "where heavy oceanic plates subduct beneath lighter continental plates".

"They are the largest faults in the world and they're all underwater," History quoted him as saying. He added that the tsunami waves could be seen like a large pebble falling in the ocean causing mega ripples.

An eye-opener for India

The Sumatra earthquake and tsunami are considered to be an eye-opener for India as they introduced the Indian coastline to tsunami and its destructible power. Learning from the unprecedented natural disaster that led to such heavy damage to life and property, the Ministry of Earth founded the Indian Tsunami Early Warning System (ITEWS) at Indian National Centre for Ocean Information Services (INCOIS), Hyderabad in October 2007.

Scientists in India are now able to predict and project movements in the Indian Ocean through real-time seismic monitoring with Bottom Pressure Recorders (BPR), tide gauges, and a 24x7 operational tsunami warning system to detect tsunamigenic earthquakes as to provide early advisories to the most vulnerable.

India eventually became the first country to establish an early warning system for tsunami detection, while Odisha became the first state in the country to get a Tsunami Ready recognition.