What is a Megatsunami?
In this video, Dr Claire Earlie explains the difference between a tsunami and megatsunami.
When looking at the 2004 Indian Ocean tsunami we again pose the question; what is regular activity and what is an extreme event?
There is no doubt that it was one of the deadliest natural disasters in recent history. From the viewpoint of its impact on human life and infrastructure it was devastating.
When we look at what causes tsunamis we see processes that are part and parcel of the dynamic Earth we live on.
Because of that we can confidently predict that we will continue to experience tsunamis of different sizes caused by earthquakes under the ocean.
Tsunamis in 2004
In that sense the 2004 Indian Ocean tsunami was caused by regular activity and it can be listed alongside a number of others that were of a similar magnitude.
Here’s a list of tsunamis that occurred in 2004:
| Date | Location and size |
|---|---|
| 5 September 2004 | Honshu, Japan (Mw 7.2) |
| 2 November 2004 | Vancouver, Canada (Mw 6.7) |
| 28 November 2004 | Hokkaido, Japan (Mw 7.0) |
| 23 December 2004 | North of MacQuarie Island, Australia (Mw 8.1) |
| 26 December 2004 | Sumatra / Indian Ocean (Mw 9.0) |
Source: International Tsunami Warning Centre
Chicxulub impact
If we contrast that with the megatsunami we heard about in the video, we see an entirely different and less predictable cause.
The megatsunami at Chicxulub in the Yucatán Peninsula, Mexico was caused by a massive asteroid impact.
Incredibly it created a megatsunami 100 metres high, this is significantly higher than any of the tsunamis that occurred in 2004.
This is incredibly rare and there have been no megatsunamis caused by asteroid impacts in recorded human history.
A truly extreme event.
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