Monster of the Deep – The Asian Tsunami of 2004

Monster of the Deep – The Asian Tsunami of 2004

The 26th December 2018 is the fourteenth anniversary of one of the great disasters of modern history – the so-called Boxing Day Tsunami of 2004.

Over a quarter of a million people died when giant waves and ocean surges pushed across the coastlines of 14 countries, including Indonesia, Thailand, Sri Lanka and India, all triggered by a massive 9.1 magnitude earthquake off the Sumatran coast in Indonesia.

Experts estimated that the quake displaced an astonishing 30 cubic kilometres of ocean water, unleashing a train of giant “ripples” that raced across the Indian Ocean. These began travelling at tremendous speed – around 800 km/hr, only a little less than the cruising speed of an Airbus A 380 – but were barely visible in the deep ocean. However as they neared coastal areas they slowed because of friction with the seabed, and ramped up dramatically in height before exploding across the shore.

About 15 minutes after the earthquake, giant waves up to an estimated 30 metres in height struck Aceh in Indonesia and around two hours later smashed across coastal areas of Sri Lanka, India and Thailand. The east coast of Africa was hit about seven hours later and effects were felt as far south as Antarctica and southeast towards the coast of Western Australia. Unusual ocean surges were also reported along the coastlines of South Australia and Tasmania.

In several locations witnesses described the classic drawback of the ocean that often precedes tsunamis – in this case the ocean retreated way back out to sea in what appeared to be a dramatically low tide, before returning in an irresistible wall that travelled kilometres inland.

The Boxing Day Tsunami is thought to be one of the deadliest in history, and the earthquake that triggered it was the third biggest ever recorded. The two larger occurrences are the earthquakes of 1960 (Chile) and 1964 (Alaska).

 

Image: The tsunami smashes across the coast at Ao Nang in Krabi Province, Thailand, 2004, courtesy of Wikimedia Commons.