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Updated numerous times with fresh media reports, after initial post
The Pacific Tsunami Warning Center has put Hawaii on watch for a possible wave. The earliest time of arrival would be 3 a.m. Hawaii time, the center estimates. The PTWC emphasizes that the watch is based simply on the size of the quake. The shaking was significant even 300 miles away in Tokyo, according to reports. There has been a tsunami surge of unknown size in at least one part of Japan, with pics showing boats and cars being carried away and buildings being immersed. There's also damage in Tokyo and closer to the quake zone, with "numerous injuries."
* USGS: The U.S. Geological Survey is calling it an 8.9 magnitude quake. Eight-point-nine, followed by at least two 6.4 aftershocks and a 7.1 quake.
10: 55 p.m. update: This is classed as a "great quake," and the tsunami warning has been extended across much of the Pacific. There has now been a 7.1 aftershock.
11 p.m. update: Astounding live video footage on CNN of tsunami surges creeping across Japanese farmland, carrying burning debris. Japan has announced it will begin accepting foreign assistance. CNN is calling out tsunami arrival times for Taiwan and other islands in the Pacific. Former KNBC reporter Kyung Lah has been on the line to CNN from Tokyo.
11:30 p.m. update: Significant tsunami inundation in the Sendai area on the east coast of Japan north of Tokyo. CNN is showing fires in scattered locations around the country. The original 8.9 quake has been followed by numerous aftershocks of 6.3 and above. The largest quake has been given these offshore coordinates by USGS:
130 km (80 miles) E of Sendai, Honshu, Japan
178 km (110 miles) E of Yamagata, Honshu, Japan
178 km (110 miles) ENE of Fukushima, Honshu, Japan
373 km (231 miles) NE of TOKYO, Japan
Only one quake as large as the main shock in Japan has ever hit the United States: Alaska's 9.2 in 1964.
Al Jazeera English is streaming live with NHK's feed, and on the air over KCET until midnight.
Great NOAA map of estimated tsunami travel times across the Pacific. Note: there is no warning in effect for Southern California:
1 a.m. final update: West Coast & Alaska Tsunami Warning Center has issued a tsunami watch for California. That just means to keep an ear open for a call to leave if a hazardous tsunami is spotted. The waves, if they arrive, would start after 8 a.m on the SoCal coast.
In Japan, the sun is going down on Friday night. Even if there are no more quakes, Saturday morning should be a sobering dawn. There's no telling how many deaths or how much damage has been inflicted already. There are fires burning, towns inundated by tsunami waters, and urban quake damage reports coming in from many areas.
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Photos from Sendai prefecture, Japan: BBC, BoingBoing.net, NHK