Japanese television showed cars, ships and even buildings being swept away by a vast wall of water after the 8.9-magnitude earthquake.
The quake has sparked fires in several areas including Tokyo, and numerous casualties are feared. It struck about 250 miles (400km) from the capital at a depth of 20 miles. There have been powerful aftershocks. The tremor hit at 1446 local time (0546 GMT). Seismologists say it is one of the largest earthquakes to hit Japan for many years.
In Tokyo, public transport has been suspended, elevators are switched off in many buildings and thousands of people have gathered in squares and around train stations.
The tsunami warning was extended to the Philippines, Indonesia, Taiwan, the Pacific coast of Russia and Hawaii.
The Pacific Tsunami Warning Center said the wave could extend as far as Chile.
In Tonga, the Tonga Meteorological Center and proper authorities immediately issued a tsunami warning. The Tonga Meteorolical Center has issued an official tsunami warning for people to just be advised and to take urgent action to protect their lives and property.
‘Ofa Fa'anunu, director for Tonga Meteological Services said that, "The latest information regarding the tsunami warning for Tonga was received at 1030 PM, and such a warning is being issued for preparation in case of any disaster."
"Locationwise, there are a lot of other Pacific Island countries in the region between Tonga and Japan. The closest to Hawaii is the U. S Territory of Guam, the Northern Mariana Islands - then there is Fiji and New Caledonia,"
"There is a widespread warning and watch for the whole of Tonga, and for people to be aware for their own safety."
Tsunami warnings are issued due to the imminent threat of a tsunami.
Issued by the: Ministry of Information and Communications, Nuku'alofa, 2011.