SENDAI, Japan (AP) - A strong earthquake rattled Japan's northeast Monday on the one-month anniversary of the massive temblor and wave that devastated the northeastern coast and unleashed a still-unfolding nuclear crisis.
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.
The agency initially issued a warning for a three-foot (one-meter) tsunami, but it was later canceled. A 7.1-magnitude quake shook the northeast coast last week, cutting power to millions of households.
Most of that electricity had been restored by Monday, but the latest aftershock sunk about 200,000 more homes into darkness.
There were no new reports of damage. Aftershocks have repeatedly rattled the disaster-weary region, but there is little left in the northeast to ruin.
The 9.0-magnitude earthquake and the tsunami it generated on March 11 are believed to have killed more than 25,000 people and caused as much as $310 billion in damage. The nuclear power plant they disabled has been spewing radiation since, and even a month on, officials say they don't know how long it will take to cool reactors there.