There's been another powerful earthquake off the North Central coast of Japan, near the location of the 9.0-magnitude temblor on March 11 that set off a tsunami that pummeled cities along the coast, leaving thousands dead or missing.
At an estimated magnitude of 7.1, today's quake is the strongest in the area since the March 11 disaster.
Immediately after the quake, the Japan Meteorological Agency a issued tsunami warning — and says the wave's height could be about 2 meters — for part of the coast. A tsunami "advisory" has been issued for parts of the coast further from the epicenter. They might get a wave about half a meter in height.
We'll keep updating this post as the story develops.
Update at 12:47 p.m. ET. Is This An Aftershock?
Here's how the U.S. Geological Survey defines an "aftershock":
"Aftershocks are earthquakes that follow the largest shock of an earthquake sequence. They are smaller than the mainshock and within 1-2 rupture lengths distance from the mainshock. Aftershocks can continue over a period of weeks, months, or years. In general, the larger the mainshock, the larger and more numerous the aftershocks, and the longer they will continue."
Update at Noon ET. Tsunami Warnings And Advisories Lifted:
The Japan Meteorological Agency just posted word that "all tsunami warnings and advisories have been cancelled."
Update at 11:45 a.m. ET. No Tsunami Waves Reported As Of Yet:
The estimated arrival time for tsunamis along parts of the coast have now come and gone. NHK, which is streaming its English-language coverage, says that no tsunami waves are reported to have reached land. It also reports that authorities say work at the crippled Fukushima Dai-Ichi nuclear power plant, where engineers are trying to keep reactors damaged in the March 11 disaster cool, continues and was not affected by today's quake.
Update at 11:25 a.m. ET. Magnitude Now Put At 7.1:
After first saying it was a 7.4-magnitude earthquake, the U.S. Geological Survey is now saying it was a 7.1-magnitude temblor. It also puts the time of the quake at 10:32 a.m. ET — 11:32 p.m. local time in Japan.
Update at 11:17 a.m. ET. Power Company Says 'No Problem' At Crippled Nuclear Plant:
The latest from Kyodo News is that "no problem at all 6 reactors of Fukushima Dai-Ichi" nuclear power plant after this latest earthquake, according to Tokyo Electric Power Co.
Update at 11:12 a.m. ET. No Word Of New Problems At Nuclear Plant:
Kyodo News has posted this breaking news alert: "No extra abnormality at Fukushima Dai-Iichi plant as of 11:50 p.m."
That is the nuclear power plant where workers are still trying to deal with crippled reactors and radioactivity.
Update at 11:07 a.m. ET. Tsunami Arrival Times:
The Japan Meteorological Agency has "estimated tsunami arrival" times for places on the coast posted here. The times have passed in some locations — but are just coming up in Sendai-ko and Fukushima prefecture.
Update at 11:03 a.m. ET: The Japan Meteorological Agency's tsunami warning — which puts the tsunami height at up to 2 meters — is for the coast of Miyagi Prefecture. The lesser "tsunami advisories" cover Iwate, Fukushima and Ibaraki prefectures.
Update at 11:01 a.m. ET: From Tokyo, NPR's Greg Dixon reports that the shaking lasted for about 2 minutes. Japan's NHK is urging anyone along the coast in the region near the epicenter to head for higher ground, Greg adds. Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.