Separate strong earthquakes rocked northern Japan and the main Philippine island of Luzon today, swaying buildings and trees but apparently not causing any serious injuries or damage, officials said. The Japanese quake registered a preliminary 5.2 on the Richter scale and was the second strong temblor to hit the northern island of Hokkaido in less than three days, Central Meteorological Agency officials said. They said it struck at 7:44 a.m. (6:44 p.m. Sunday) and was centered in the Hidaka mountain range, 45 miles away from Saturday's earthquake, which measured a preliminary 6.4 on the scale. Local police said there were no immediate reports of damage or casualties. The pre-dawn Philippine earthquake struck at 3:45 a.m. (3:55 p.m. Sunday) and registered a preliminary 5.4 Richter reading, the Royal Observatory of Hong Kong said. The Philippine Institute of Volcanology and Seismology said it was centered 110 miles northwest of Manila under the Luzon Sea. Earthquakes measuring 5 on the open-ended Richter scale are classified as strong and capable of causing considerable damage in populated areas. However, both quakes were located deep below the earth's surface and therefore caused little damage, officials said. Both earthquakes also occurred in quake-prone areas where edges of the earth's crustal plates are thought to rub together, a Central Meteorological Agency official said. ``It's been some time since we had earthquake activity in that area of Hokkaido, so it's not surprising to have some now caused by a build-up of pressure between the plates,'' he said, speaking on condition of anonymity. The official said there was no way of knowing whether the Japanese quake was related to the one in the Philippines, 2,250 miles away. The Philippine islands are thought to be located on the edge of a separate, smaller crustal plate which extends up to southern Japan. Institute spokesman Ulpiano Trillanes said the Philippine earthquake affected a wide area of Luzon island, including Manila, but apparently caused no serious damage or injuries. In the past 35 years there have been two major earthquakes in Hokkaido. In 1968, the Tokachi-Oki earthquake measuring a 7.9 on the Richter scale killed 52 people. The Richter scale measures the total magnitude of an earthquake. Every increase of one digit in the scale represents a tenfold increase in magnitude, thus a reading of 4.5 would be 10 times stronger than one of 5.5.
A strong earthquake that measured 5.2 on the Richter Scale rocked the northern Japanese Island of Kokkaido at about at about 7:45 local time today. The quake was felt as far away as Tokyo, and there were reports of damage in other parts of Japan. Every increase of one integer on the scale represents a tenfold increase in strength, thus a quake measuring 5.2 is ten times stronger than one of 4.2. Today's quakes caused little damage because they occurred far below the earth's surface. The last quake to cause great destruction in Hokkaido occurred in 1968. It measure 7.9 and claimed 52 lives.