Facts About Tsunamis

Tsunamis form through a complex, multi-stage process that emanates from the massive energy release of a submarine earthquake, underwater or coastal landslide, or volcanic eruption.

Claiming the lives of over 200,000 people, the Indian Ocean tsunami of 2004 was literally off-the-scale in terms of both damage and destruction.

On 26 December 2004, an undersea megathrust earthquake caused a huge earth subduction and triggered a series of devastating tsunamis that ravaged almost all landmasses bordering on the Indian Ocean, killing over 230,000 people in 14 different countries. The hypocenter of the main earthquake was approximately 160km (100mi) off the western coast of northern Sumatra and emanated from the ocean floor 30km (19mi) below the area’s mean sea level. Here, a massive rupture in the ocean floor caused massive tectonic plate movement – an event felt as far away as Singapore – as well as the creation of numerous secondary faults that elevated the height and speed of generated waves to titanic levels.

The fallout from the earthquake and resulting tsunami was the worst for over 50 years, with the event releasing a total of 1.0007 joules of energy. This level of energy release was comparable to 26.3 megatons of TNT, over 1,502 times the energy released by the Hiroshima atomic bomb. Indeed, the rupture was so severe that the massive release of energy was so great it slightly altered the Earth’s rotation, causing it to wobble on its axis by up to 2.5cm.

Facts About TsunamisFurther, when the British Royal Navy vessel HMS Scott surveyed the seabed around the earthquake zone with a multi-beam sonar system, it revealed that it has drastically altered its topography. The event has caused 1,500m ridges to collapse into massive landslides kilometres long. The momentum of the water displaced by tectonic upshift had also dragged massive million-ton rocks over 10km on the seabed and an entirely new oceanic trench had been exposed.

Indian Ocean tsunami facts

  • Height – 30 meters
  • Deaths – 230.000
  • Money raised – 7bn USD
  • Countries Affected – 14
  • Earthquake magnitude – 9.3

Historic Tsunamis

1. Messina Tsunami

The Messina earthquake of 1908 triggered a large tsunami 12 metres high that levelled entire buildings and killed more than 70,000 people in Sicily and southern Italy. The earthquake that generated it measured 7.5 on the Richter scale and caused the ground to shake for between 30 and 40 seconds.

Tsunamis2. The Valdivia earthquake Tsunami

The Valdivia earthquake of 1960 caused one of the most damaging tsunamis of the 20th Century. Thousands of people were killed by it and it stretched as far as Hilo, Hawaii. Measuring 9.5 on the Richter scale, the earthquake caused waves up to 25 metres to assault the Chilean coast. The earthquake also triggered landslides and volcanic eruptions.

3. Lituya Bay Tsunami

After an earthquake caused a landslide at the head of Lituya Bay, Alaska, in July 1958, a massive tsunami was generated measuring over 524 metres in height, taller than the Empire State Building. Amazingly, despite the awesome height of the tsunami, only two fishermen operating in the bay were killed by it.