A 4-inch (10-centimeter) tsunami rippled to shore 35 minutes later, but there were no signs of damage.
"There was some light shaking, but it was nothing major," said Yukio Yoshida, a police spokesman in Hokkaido.
Authorities temporarily advised about 10,600 residents of Ofunato in Iwate Prefecture (state), about 125 miles (200 kilometers) northeast of Tokyo, to evacuate their homes and ordered people to stay away from beaches.
An hour earlier, northeastern Indonesia was hit by a 6.6-magnitude quake that struck 55 miles (90 kilometers) beneath the Molucca Sea, the U.S. Geological Survey. Though on the same tectonic plate, the temblors were unrelated, local officials said.
A tsunami alert was briefly issued over the radio and television and people in the Maluku capital of Ternate, which was closest to the epicenter, fled from houses and buildings as the earth rumbled beneath them.
The feared wave never came, however, and there were no reports of casualties or damage.
"I ran out of the hotel with other guests and we fled to high ground," Benyamin Otte said. "I could see people on the beach, checking to see if the were any signs of a tsunami, but everything looked normal. Within a half hour, we were heading back down."
Indonesia and Japan are both prone to seismic upheaval due to their location on the so-called Pacific "Ring of Fire," an arc of volcanos and fault lines encircling the Pacific Basin.
In December 2004, a massive earthquake off Indonesia's Sumatra island triggered a tsunami that battered much of the Indian Ocean coastline and killed more than 230,000 people -- 131,000 of them in Aceh province alone.
A tsunami off Java island last year killed nearly 5,000.
Japan also is one of the world's most earthquake prone nations. In 1995, a magnitude-7.2 quake in the western port city of Kobe killed 6,400 people and experts believe Tokyo has a 90 percent chance of being hit by a major quake over the next 50 years.
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