A warning for a small wave is issued on the one-month anniversary of the giant quake and tsunami.

© Kyodo NewsSurvivors in Miyako, Japan, observe a moment of silence in the rubble exactly a month after a massive earthquake and tsunami.
A strong earthquake rattled Japan's northeast Monday and sparked a fresh tsunami alert on the one-month anniversary of the massive temblor and wave that devastated the northeastern coast and unleashed a still-unfolding nuclear crisis.

The 7.1-magnitude aftershock briefly forced Tokyo's main international airport to close both of its runways. The epicenter was just inland and about 100 miles north of Tokyo. The operator of the crippled Fukushima Daiichi nuclear complex said the latest quake had no impact on the plant.

A warning was issued for a three-foot tsunami, the same as for after an aftershock that shook the northeast coast last week. That quake generated no tsunami.

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.

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. Last Thursday's 7.1-magnitude aftershock, which had been the strongest tremor since the day the original quake hit, did sink hundreds of thousands more households into darkness, however. Most of that electricity has been restored.

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.

Source: The Associated Press