Quote: "A tsunami of about 2 meters (6.5 feet) or more could hit the Pacific coast of Japan's northernmost island of Hokkaido and main island of Honshu after 1210 GMT, the agency warned. A live video from Nemuro, a port on Hokkaido, showed calm seas and there were no immediate reports of any tsunami there. There were also no immediate reports of injuries or damage caused by the quake, which residents said could barely be felt in Japan. 

The earthquake that generated the Asian Tsunami measured around 9-10 on the Richter Scale and lasted for 10 minutes. The waves that were created by the earthquake struck a dozen countries on boxing day, causing mass devastation and resulted in the deaths of around a quarter of a million people. Subsequent to the catastrophe, a tsunami warning system was set up which advises on the probability of tsunamis being generated by large earthquakes.

Quote: "The Tsunami Warning System (TWS) in the Pacific, comprised of 26 participating international Member States, has the functions of monitoring seismological and tidal stations throughout the Pacific Basin to evaluate potentially tsunamigenic earthquakes and disseminating tsunami warning information. The Pacific Tsunami Warning Center (PTWC) is the operational center of the Pacific TWS. Located near Honolulu, Hawaii, PTWC provides tsunami warning information to national authorities in the Pacific Basin.

Source Hindu, Tsunami Warning System