Japan Rattled by 7.1 Aftershock; No Nuclear Damage Reported

A magnitude-7.1 aftershock, one of the strongest since the devastating earthquake March 11, struck Japan today 215 miles (345 kilometers) northeast of Tokyo.

At least three nuclear facilities lost some outside power, according to official and news media reports, although none was reported in distress.

The quake was measured at a depth of about 25 miles and struck about 11:32 p.m. local time near the site of last month’s quake, the largest on record in Japan, the U.S. Geological Survey reported on its website. A tsunami alert for a possible two-meter wave was canceled by Japan about two hours later.

“What occurred today is an aftershock in the same area and rupture zone to the magnitude-9 main shock that occurred about a month ago,” said Don Blakeman, a geophysicist in the U.S. National Earthquake Information Center in Golden, Colorado. “It is tremendously smaller than the main shock. The main shock caused about 80 times more ground movement.”

Tokyo Electric Power Co. told reporters that the quake caused no new disruption at the Fukushima Dai-Ichi and Dai-Ni nuclear power units. The Fukushima units were crippled by the magnitude-9 quake and tsunami on March 11 that left more than 27,000 people dead or missing and caused an estimated 25 trillion yen ($295 billion) in damage.