A harrowing 8.9 earthquake hit Japan tonight. The New York Times reports: "A tsunami hit the coast of northeast Japan on Friday in the aftermath of an 8.9 magnitude earthquake about 80 miles offshore. Television images showed waves of more than 12 feet roaring inland. CNN reported that air and land transportation was severely disrupted."

The quake struck at around at 2:46 p.m. Tokyo time just off Honshu, "Japan’s most populous island."

An estimated 4 million people are without power.

According to BBC, the following tsunami caused "caused extensive damage" with residents trapped inside their buildings. "Japan's TV showed cars, ships and even buildings being swept away" and "wave as high as 6m (20ft)" could hit the coast.

To give you perspective on the gravity of the Japanese earthquake, the Loma Prieta quake measured 6.9 and the Great San Francisco Quake of 1906 measured 7.9. Today's quake is one of the largest five recorded since 1900.

No word yet on number of casualties, which will presumably be high. A tsunami watch is in effect for Hawaii.

Update 12:25 a.m.: A tsunami watch has been issued for California. Estimated time of arrival for San Francisco: 8:08 - 8:16 a..m. (Note: a watch isn't as severe as a warning.)

12:39: Quake has been downgraded to 8.8. Expect this number to fluctuate throughout the morning.

12:50: Per ABC 7, the 'tsunami watch' has been upgraded to 'tsunami warning' for the California coast. If you're near the coast, head to higher ground. The estimated time of arrival will now be 8:08 a.m. Remember, folks: this is a possibility, not a certainty, that a minor tsunami could reach our coastline.

The National Weather Association has more detailed information. Also, here's a map of expected travel times of the wave.