On Friday 11 March 2011 at 14:46:24, an earthquake of magnitude 9.0 on the Richter scale occurred. It was at the point where the Pacific tectonic plate slides beneath the North American plate. The epicentre was 30 kilometres below the Pacific Ocean seabed and 129 km off the east coast of Honshu, Japan. This triggered a tsunami. High, powerful waves were generated and travelled across the Pacific Ocean. The area worst affected by the tsunami was the east coast of Honshu in Japan.