The aftershock briefly forced Tokyo’s main international airport to close both of its runways. The operator of the crippled Fukushima Dai-ichi nuclear complex said power was cut but quickly restored and the lack of electricity had not endangered operations.
Japan’s meteorological agency measured the aftershock at a magnitude of 7.0, but a U.S. monitor said it was 6.6. The epicenter of was just inland and about 100 miles (160 kilometers) north of Tokyo.
People at a large electronics store in the northeastern city of Sendai screamed and ran outside, though the shaking made it hard to move around. Mothers grabbed their children, and windows shook. After a minute or two, people returned to the store.