A moderately strong earthquake with a preliminary magnitude of 5.1 jolted eastern Japan and Tokyo on Thursday, the Meteorological Agency said, less than a week after a strong quake hit the capital, injuring at least 18, reported Reuters There were no immediate reports of injuries or damage from the 7:15 p.m (1015 GMT) quake, and the agency said there was no danger of a tsunami. Some bullet trains stopped but soon resumed operations, while Tokyo's Haneda airport briefly closed for runway checks. The focus of the tremor was 50 km (31 miles) below the surface of the earth, in Ibaraki prefecture, slightly northeast of Tokyo, the Meteorological Agency said. A Reuters witness said the quake shook Tokyo's National Stadium, which was packed with fans for a soccer match between Britain's Manchester United and Japan's Kashima Antlers. The earthquake measured four on the Japanese intensity scale, which measures ground motion. A quake with that reading causes hanging objects to swing considerably and makes dishes in a cupboard rattle. On Saturday afternoon, Tokyo was shaken by a 6.0 magnitude quake that halted trains and briefly closed airports. It was not immediately known whether Thursday's quake was an aftershock. The magnitudes of the earthquakes were measured according to a technique similar to the Richter scale, but adjusted for Japan's geological characteristics. Earthquakes are common in Japan, one of the world's most seismically active areas. The country accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater. In October 2004, an earthquake with a magnitude of 6.8 struck the Niigata region in northern Japan, killing about 40 people and injuring more than 3,000. That was the deadliest quake since a magnitude 7.3 tremor hit the city of Kobe in 1995, killing more than 6,400.
