The majority of lives were lost in Indonesia, with 167,540 people listed as dead or missing and twenty-six Australians were killed, almost all in Thailand. According to the Australian Disaster Resilience Knowledge Hub, the total cost of damage in the region is estimated at $10 billion ($AUD 14 billion).
As of 2016, 400 bodies still remained unidentified in Thailand.
How it happened
At 7.59 am local time, a 9.1 magnitude earthquake struck the coast of Sumatra in Indonesia - it was the third strongest earthquake recorded in the world since 1900.
It was triggered when 30km below the seafloor, a 1200 kilometre stretch of the Indian tectonic plate was pushed up 20m under the Burma plate, raising the seafloor by several metres and displacing 30 cubic kilometres of water.
Within 20 minutes, the tsunami had reached Sumatra and the Nicobar Islands in Indonesia, with waves of up to 30m recorded in the Aceh region. The wave took approximately two hours to reach Thailand and Sri Lanka, and three hours to hit the Maldives.
What’s changed since?
In 2004, the region lacked a co-ordinated Indian Ocean tsunami warning system and the awareness of tsunamis - and how to spot them - was relatively low.
Since then, awareness and infrastructure has improved, but some social media users are using the anniversary and the recent tragedy to point to continuing issues with Indonesia’s tsunami warning system.
Following the disaster in 2004, a network of seafloor sensors, data-laden sound waves and fibre-optic cable was meant to be developed using $3 million in assistance from the US National Science Foundation.
But due to alleged “inter-agency wrangling” and disputes over funding, the project has not moved further than the prototype stage and is yet to be deployed.
Following the deadly Sulawesi tsunami in September this year, the lack of warnings raised questions as to whether the new system, if completed, would have saved lives. The tsunami killed more than 2000 people.
“To me, this is a tragedy for science, even more so a tragedy for the Indonesian people as the residents of Sulawesi are discovering right now," University of Pittsburgh expert in disaster management Louise Comfort said following the tragedy.
Indonesia quake-tsunami: Is it time for a rethink of warning systems?
"It's a heartbreak to watch when there is a well-designed sensor network that could provide critical information.”
The Indonesian government, however, denied claims it issued inadequate safety warnings, following the powerful earthquake that triggered the wave.
Indonesia’s current warning system is made up of sea-bed sensors which are able to detect changes in pressure that could indicate an incoming tsunami and a number of buoys which receive the data and transmit it to satellites.
But an earthquake near Sumatra in 2016 revealed that 22 of these buoys were not working and had not been since 2012.
Where to now?
After Saturday’s tragedy, Indonesian President Joko Widodo ordered the country's Meteorology, Climatology and Geological Agency (BMKG) to develop systems "that can provide early warnings to the community."
But experts say that, unlike tsunami caused by earthquakes, little could have been done in time to alert people that waves were coming.
Head of public relations for the Indonesian National Board for Disaster Management Sutopo Purwo Nugroho tweeted on Saturday that while the country is currently unable to detect tsunamis caused by underwater landslides and volcanic eruptions, the earthquake warning system is “running well”.
“Less than 5 minutes after the earthquake, BMKG can notify the public,” he said on Twitter.
The existing system can detect and monitor underwater earthquakes but cannot pick up landslides and volcanic eruptions, which can also trigger massive waves.
The Indonesian government has announced it will now begin work on a new warning system capable of detecting undersea landslides, the BBC has reported.
Iyan Turyana, a spokesman for the Agency for the Assessment and Application of Technology, told the BBC that the new system would address the holes in the current system and be capable of detecting landslides.