A major earthquake registering 7.1 on the Richter scale struck off northeastern Honshu Island early today, officials said. Three coastal villages were ordered evacuated for fear of tidal waves, officials said. There were no immediate reports of casualties or damage from the quake, which struck at 3:26 a.m. Thursday (1:26 p.m. Wednesday EST). It was centered about 60 miles off the coast and at a depth of 20 miles, the Central Meteorological Agency in Tokyo said. After the quake, officials closed the major expressway through the affected region for inspection and overnight trains were stopped to check the condition of the rails. The agency warned of a tsunami, or seismic tidal wave, hitting coastal towns on northeast Honshu and the northernmost main island of Hokkaido. The agency said sea levels two hours after the quake had risen nearly three feet in the region. Officials ordered the evacuation of the villages of Taro, Sanriku and Ozutsu, about 300 miles northeast of Tokyo on Honshu's eastern coast. The agency said the quake had a magnitude of 7.1 on the Richter scale, the same as the Oct. 17 earthquake that devastated the San Francisco Bay area. In Washington, the U.S. Geological Survey said the quake measured 7.3 on the Richter scale. U.S. Geological Survey scientists said they recorded an aftershock measuring 5.8 about 10 minutes after the main quake. The main earthquake was the strongest in that region in more than 58 years, since a magnitude 7.7 earthquake March 9, 1931, said Don Finley, a spokesman for the U.S. agency. The earthquake occurred in the same general area as a series of earlier tremors during the past several weeks. The strongest of the earlier quakes was a magnitude 6.5 on Sunday. The Richter scale is a measure of ground motion as recorded on seismographs. Every increase of one number means a tenfold increase in magnitude. Thus a reading of 7.5 reflects an earthquake 10 times stronger than one of 6.5. An earthquake of 3.5 on the Richter scale can cause slight damage in the local area, 4 moderate damage, 5 considerable damage, 6 severe damage. A 7 reading is a ``major'' earthquake, capable of widespread heavy damage; 8 is a ``great'' quake, capable of tremendous damage. Japan is situated on a major fault line that produces frequent earthquakes, few of which cause serious damage.
A major earthquake registering 7.1 on the Richter Scale struck off Honshu early today. It was centered 60 miles off the coast and at a depth of 20 miles. No casualties have been reported, but officials fear a seismic tidal wave. Over the past few weeks a series of lesser quakes have occurred in the same general area. The first quake hit just after midnight local time (0900 GMT) with its epicenter near the town of Minamisanriku, about 30 miles from Tokyo. A major fault runs under Japan, and it is the reason for frequent quakes, but most of them cause little damage.