In Japanese the word tsunami literally translates as ‘harbour wave’. Tsunamis are a frequent occurrence in Japan, with other 195 recorded throughout history so far.
It was the Greek historian Thucydides who first linked tsunamis to earthquakes. However, their exact cause remained speculative until the 20th Century.
Out as sea tsunamis travel incredibly quickly, often clocking up over 500mph. This speed slows as it reaches the shoreline, often being reduced to around 50mph.
The first part of a tsunami to reach land is referred to as a ‘trough’. Here water along the shore recedes dramatically in a mass drawback, exposing normally submerged areas.
Due to their destructive nature, tsunami-related activity is monitored by specialist observation centres such as the Pacific Tsunami Warming Center in Honolulu.