TOKYO » Twelve people suffered minor injuries and businesses returned to normal Sunday after a powerful earthquake near remote Japanese islands shook most of the country the previous night, but it was well beneath the earth’s surface and did not trigger a tsunami.

The magnitude-7.8 quake struck off the Ogasawara islands Saturday night at a depth of 421 miles, the U.S. Geological Survey said.

It was followed by a magnitude-6.4 quake Sunday morning off Japan’s Izu islands, which are north of the Ogasawaras.

The latest quake struck at a depth of 8 miles with the epicenter 390 miles southeast of Tokyo. It was not strong enough to generate a tsunami warning or close enough to the islands to cause any significant damage or injuries, said John Bellini, a USGS geophysicist in Golden, Colorado. He said it is considered a separate seismic event and not an aftershock from Saturday’s quake.

Saturday night’s temblor was powerful enough to rattle most of Japan, from the southern islands of Okinawa to Hokkaido in the north. It caused buildings to sway in Tokyo — about 620 miles north of the Ogasawara islands — and temporarily disrupted some train services in the city. About 400 houses in Saitama prefecture, just north of the capital, were without power, according to the Tokyo Electric Power Co.

At Tokyo’s Roppongi Hills shopping and business complex, elevators stopped soon after the magnitude-7.8 earthquake struck, forcing hundreds of visitors to climb down the stairs. Among them were about 200 people who came to see the Star Wars exhibit on the 52nd floor.

The Fire and Disaster Management Agency said that 12 people were injured, including with burns, cuts, bruises and from falls.

At an inn on the Ogasawara island of Hahajima, furniture shook violently, although nothing fell or broke, innkeeper Michiko Orita told NHK. "It was so frightening. The entire house shook and a Buddhist altar violently swayed like I have never experienced before," she said, adding that all her guests were safe.

In March 2011, a magnitude-9.0 earthquake rocked northeastern Japan, triggering a tsunami that killed more than 18,500 people and ravaged much of the northern Pacific coast. The depth of that quake was just 15 miles, according to the meteorological agency.