Tokyo is situated on Japan's main Honshu island which is turn sits at the intersection of three continental plates, the Eurasian, Pacific and Philippine Sea plates, which are slowly grinding against each other, building up enormous seismic pressure that every so often is realised with ferocious force.
Volcanoes and oceanic trenches around the Pacific Basin which holds Japan have earned the area the name The Ring of Fire.
Japan accounts for about 20 per cent of the world's earthquakes of magnitude six or greater and on average, an earthquake occurs there every five minutes.
When earthquakes occur under the sea floor, they unleash tsunamis which are often more devastating than the quake itself.
Tsunamis, from the Japanese word for harbour and wave, are vast quantities of water displaced by the violent movement of the earth's crust.