True Crime/Paranormal/Conspiracy Theories Part VII

2004 Boxing Day Tsunami Part I

On 26 December 2004, at 07:58:53 local time (UTC+7), a major earthquake with a magnitude of 9.2–9.3 Mw struck with an epicenter off the west coast of northern Sumatra, Indonesia. The undersea megathrust earthquake, known by the scientific community as the Sumatra–Andaman earthquake, was caused by a rupture along the fault between the Burma Plate and the Indian Plate, and reached Mercalli intensity up to IX in some areas.

A massive tsunami with waves up to 30 m (100 ft) high, known as the Boxing Day Tsunami after the Boxing Day holiday, or as the Asian Tsunami, devastated communities along the surrounding coasts of the Indian Ocean, killing an estimated 227,898 people in 14 countries in one of the deadliest natural disasters in recorded history. The direct results caused major disruptions to living conditions and commerce in coastal provinces of surrounded countries, including Aceh (Indonesia), Sri Lanka, Tamil Nadu (India) and Khao Lak (Thailand). Banda Aceh reported the largest number of deaths. It is the deadliest natural disaster of the 21st century, and the worst tsunami disaster in history. It is also the worst natural disaster in the history of Indonesia, Sri Lanka and Thailand.

It was the most powerful earthquake ever recorded in Asia, the most powerful earthquake in the 21st century, and at least the third most powerful earthquake ever recorded in the world since modern seismography began in 1900. It had the longest fault rupture ever observed, between 1,200 km to 1,300 km (720 mi to 780 mi), and had the longest duration of faulting ever observed, at least ten minutes. It caused the planet to vibrate as much as 10 mm (0.4 in), and also remotely triggered earthquakes as far away as Alaska. Its epicenter was between Simeulue and mainland Sumatra. The plight of the affected people and countries prompted a worldwide humanitarian response, with donations totalling more than US$14 billion (equivalent to US$23 billion in 2023 currency).

Earthquake

2004 Indian Ocean

Humanitarian response

Military operations

The 2004 Indian Ocean earthquake was initially documented as having a moment magnitude of 8.8. The United States Geological Survey has its estimate of 9.1. Hiroo Kanamori of the California Institute of Technology estimates that Mw 9.2 is best representative of the earthquake's size. However, more recent studies estimate the magnitude to be Mw 9.3. A 2016 study estimated the magnitude to be Mw 9.25, while a 2021 study revised its 2007 estimate of Mw 9.1 to a new magnitude of Mw 9.2.

The hypocenter of the main earthquake was approximately 160 km (100 mi) off the western coast of northern Sumatra, in the Indian Ocean just north of Simeulue island at a depth of 30 km (19 mi) below mean sea level (initially reported as 10 km or 6.2 mi). The northern section of the Sunda megathrust ruptured over a length of 1,300 km (810 mi). The earthquake (followed by the tsunami) was felt in Bangladesh, India, Malaysia, Myanmar, Thailand, Sri Lanka and the Maldives. Splay faults, or secondary "pop up faults", caused long, narrow parts of the seafloor to pop up in seconds. This quickly elevated the height and increased the speed of waves, destroying the nearby Indonesian town of Lhoknga.

Indonesia lies between the Pacific Ring of Fire along the north-eastern islands adjacent to New Guinea, and the Alpide belt that runs along the south and west from Sumatra, Java, Bali, and Flores to Timor. The 2002 Sumatra earthquake is believed to have been a foreshock, preceding the main event by over two years.

Historical comparisons

Great earthquakes, such as the 2004 Indian Ocean earthquake, are associated with megathrust events in subduction zones. Their seismic moments can account for a significant fraction of the global seismic moment across century-scale periods. Of all the moment released by earthquakes in the 100 years from 1906 through 2005, roughly one eighth was due to the 2004 Indian Ocean earthquake. This quake, together with the Great Alaskan earthquake (1964) and the Great Chilean earthquake (1960), account for almost half of the total moment.