Updates:

1:59 pm EST - Even though no additional damage to the Fukushima Daiichi plant has been reported, the New York Times warns about what could happen if a strong aftershock arrives:

Experts have said that a big aftershock poses an additional risk to the Fukushima plant because its containment structures are filled with water that was used in the cooling efforts and is now highly radioactive. The strain from holding that water could make the structures more vulnerable to rupture in the event of an earthquake...

12:22 - Now the depth of the quake is being estimated at 60 km, according to the meteorological officials briefing NHK. Earlier it was reported at a more shallow depth, 40 km.

12:19 - Meteorological officials are still urging caution even though tsunami alerts have officially been lifted, according to a briefing on NHK's English live feed.

12:15 - Radiation levels at Fukushima are "within ordinary range" an operator says, via BBC Breaking News.

12:10 - 402 workers were at the Fukushima plant at the time of the quake, no injuries were reported says NHK.

12:04 pm EST - Efforts to cool reactors 1, 2 and 3 at the crippled Fukushima Daiichi nuclear power plant are "continuing in a stable manner" according to NHK (via Reuters).

11:51 - All tsunami alerts and advisories have been lifted for northeast Japan reports NHK on its English language feed.

11:49 - CNN reports that workers were "evacuated" from the Fukushima nuclear facility. Unclear if that phrasing means something different from the NHK observation that workers had taken shelter (live English language feed).

11:47 - "The quake was strong enough to shake buildings in Tokyo, 265km to the south," observes BBC News.

11:45 - A geophysicist quoted by CBS News says the quake struck "at about the same location and depth as the March 11 quake. It's the strongest of the more than 1,000 aftershocks that have been felt since, except for a 7.9 aftershock that day."

11:38 - "Quake knocked out power from several nuke plants, which are now using emergency power, Tokyo-based nuclear safety agency tells @BreakingNews"

11:33 am EST - Reuters flash reports "no irregularities" were found at the crippled Fukushima plant after the estimated 7.1 aftershock hit.

Original Post:

A magnitude 7.1 earthquake (scaled back from an original 7.4 measurement) has hit Japan near the eastern coast of Honshu. According to the USGS, the quake occurred at a depth of 25 miles and is estimated to have hit 215 miles away from Tokyo. The AP reported that a tsunami alert was issued for the northeast coast--the same area hit hardest by the March 11 quake which measured 9.0--warning of waves up to 2 meters.

According to Reuters, the quake hasn't had an impact on the crippled Fukushima Daiichi nuclear power station, which is 90 miles away from the epicenter of the quake. No injuries were reported among the TEPCO workers at the plant, but NHK's English live TV feed has reported that these workers have temporarily taken shelter at the facility.

The news outlet also relayed an alert from Japan's NHK public television saying that those "in areas where the tsunami warnings were issued should evacuate to higher ground."

Thursday's quake is currently measured at a larger magnitude than the Kobe Quake of 1995, which measured at a magnitude of 6.8. This is the strongest aftershock--assuming it can be so termed--to have occurred since March 11, which resulted in an estimated 25,000 lives lost and $300 billion dollars worth of damage.

In a flash reaction, the Dow has taken a tumble from the initial reports.

Video:

Via Business Insider, here's footage of the tremor in Sendai: