TOKYO -- A strong earthquake shook northern Japan early Saturday, but there were no immediate reports of deaths or injuries. A less powerful earthquake around midnight in the same area had reportedly injured at least 11 people.
The 7:13 a.m. earthquake with a preliminary magnitude of 6.2 shook Miyagi Prefecture, about 190 miles northeast of Tokyo, the Meteorological Agency said.
Residents interviewed on public broadcaster NHK TV said the ground shook, rattling shelves and causing blackouts in some areas. NHK said there was no danger of tsunami, or giant waves caused by earthquakes.
The earlier earthquake had a preliminary magnitude of 5.5 and was centered in the northeastern prefecture of Miyagi.
The quake was most strongly felt in the neighboring towns of Yamotocho and Narusecho, about 190 miles northeast of Tokyo.
NHK said police received reports that 11 people in the prefecture had been injured and were treated at hospitals.
Miyagi prefectural police official Hidenori Takahashi said there were scattered reports of damaged rock walls and water pipes, but no major structural damage. Some roads were closed and train lines temporarily halted for safety checks, he said.
Homes and businesses in at least two towns near the quake's epicenter lost power, Kyodo news agency said.
In Yamotocho, the initial violent tremor and aftershocks lasted for about a minute and knocked items off store shelves, said Hirofumi Ueno, a 7-Eleven convenience store employee.
An earthquake of magnitude 5 or higher can cause considerable damage when centered in a heavily populated area.
Japan is one of the world's most earthquake-prone countries, sitting atop four tectonic plates, slabs that move across the earth's surface.