A powerful earthquake measuring a magnitude of 8.3 degrees on the Richter scale shook northwestern Pacific on Saturday at around 1:30 PM (0430 GMT). Small tidal changes were observed at Japan's northeast coast after the issue of tsunami warning.

Tidal changes of around 10 centimeters have been observed at Kushiro, Nemuro and Tokachi port, in Hokkaido of northern Japan at around 3:00 PM (0600 GMT), the NHK public television said.

The quake occurred at around 1:24 PM local time (0424 GMT). Its epicenter is 30 kilometers underground at 46.1 degrees northern latitude and 154.2 degrees eastern longitude, the agency said.

According to the tsunami warning issued at 1:36 PM (0436 GMT),Japan's northernmost island of Hokkaido and a wide swathe of northeastern and eastern Honshu could be affected by the earthquake.

Under the Japanese seismic classification system, which measures the intensity of tremors on the Earth surface, the quake measured 3 degree on some parts of Hokkaido including Kushiro, Hakodate and Nemuro.

An evacuation advisory has been issued in 14 municipalities around the region, targeting a total of some 37,000 households, Kyodo News said. The Japanese government has set up a liaison office at the prime minister's office in Tokyo following the tsunami warning. Japan's coastal security authority has also issued sailing warnings.

(Xinhua News Agency January 13, 2007)