It's devastating coastal areas. The Wall Street Journal reports the quake is a magnitude 8.9:

That makes it the fifth largest recorded world-wide since 1900, according to the U.S. Geological Service, larger than the 7.9-magnitude Great Kanto Earthquake that devastated Tokyo in 1923 or the 6.8 magnitude quake that hit Kobe in 1995.

If you're anywhere in the Pacific Ocean, go here and check local tsunami warnings. For Dish readers in Hawaii:

Hawaii Civil Defense is advising all residents in tsunami inundation zones to evacuate immediately.The alert, issued at 10:38, reads "Leave all coastal evacuation zones immediately. Refer to Hawaiian Telcom or Paradise Pages for evacuation maps." 

The earliest that hazardous waves could hit Hawaii is 2:59 a.m., said the agency, according to Pacific Tsunami Warning Center, based in Ewa Beach.

Other locales named in warnings:

Russia and Indonesia, Central American countries like Guatemala, El Salvador and Costa Rica...In the Philippines, the government issued a warning for 19 provinces along the coast, possibly affecting hundreds of thousands of people. A tsunami could could hit by 6 p.m. (5 a.m. ET), it said.

The LA Times reports on the potential impact on the West Coast:

A tsunami warning has been issued for the central and northern California coast and Oregon, the National Weather Service announced early Friday. In the San Francisco Bay Area, an emergency warning system announcement for a tsunami warning was braodcast just after 1 a.m. Waves could begin arriving in Crescent City, Calif., at 7:23 a.m. and the Bay Area shortly after 8 a.m.

A lower-level tsunami advisory was issued for the Southern California coast south of Point Concepcion, which includes southern San Luis Obispo County and the counties of Ventura, Los Angeles, Orange and San Diego.

A map showing tsunami travel times is here. Google victim finder for Japanese victims and their families here.

Live feed on Japanese TV here. Al Jazeera here.

National Geographic has the best general primer on tsunamis I've found so far.

UPDATES:

– 2:30 PST. BBC World has footage of a huge ocean whirlpool. Here's what it looked like inside a Japanese supermarket. And a home as the occupants evacuated. Other videos: a sea of floating cars; an airport runway is quickly overrun by water; a view from the air; the scene in an office; inside a department store; an explosion at an industrial facility.

Al Jazeera English puts confirmed death toll at 29 people, a figure expected to rise.

– 2:48 PST. Updated times for when waves will hit West Coast of United States:

PORT SAN LUIS HARBOR 8:09 a.m. SANTA BARBARA HARBOR  8:17 a.m. SANTA MONICA: 8:32 a.m. SAN PEDRO 8:32 a.m. NEWPORT BEACH 8:45 a.m. LA JOLLA 8:48 a.m.

Officials don't expect the waves to cause damage. But as a precaution, officials are likely to urge people to avoid beach areas. Officials said people living in low-lying coastal areas should seek higher ground as a precaution and listen for special instructions from emergency agencies. Unusual wave action from the quake might last for several hours.

One bit of good news: "The four Japanese nuclear power plants closest to Friday's major earthquake in Japan have been safely shut down, the International Atomic Energy Agency said."

– 3:19 PST. Obama's statement:

Michelle and I send our deepest condolences to the people of Japan, particularly those who have lost loved ones in the earthquake and tsunamis. The United States stands ready to help the Japanese people in this time of great trial. The friendship and alliance between our two nations is unshakeable, and only strengthens our resolve to stand with the people of Japan as they overcome this tragedy. We will continue to closely monitor tsunamis around Japan and the Pacific going forward and we are asking all our citizens in the affected region to listen to their state and local officials as I have instructed FEMA to be ready to assist Hawaii and the rest of the U.S. states and territories that could be affected.

– 3:25 PST. Kenneth Maxwell is blogging at the Wall Street Journal:

The aftershocks rocking Tokyo on a regular basis are unpleasant enough. But one of the most unwelcome things in a major earthquake in Japan, it turns out, is the special audible electronic alert that sounds across TV networks when Japan’s sophisticated network of earthquake detection machinery picks up on a big shake coming.

The alert is a 10-second warning, accompanied by an on-screen map that pinpoints the epicenter of the quake with the indication that a major shake is on the way. And what follows is one of the most unwelcome 10-second periods a Tokyoite might encounter.

– 3:28 PST. From a friend of The Dish:

We have been experiencing smaller tremors sporadically over the past few months, so when I first felt the earthquake, I assumed it would be just a small five second movement. But it just kept getting bigger and bigger and bigger. I was alone in my apartment on the top floor of our complex, and I had no idea what to do since I had never experienced anything like this. As I could feel the whole building shaking violently, I tried calling my roommates (originally California residents- I assumed they'd know what to do) amidst the sounds of miscellaneous things in my apartment crashing to the floor. After a few minutes the shaking subsided, but it felt like an eternity.

Even three hours later we are still feeling the aftershocks. Tokyo city is in chaos, as 3 of the 4 major power plants are down, and all trains have been shut down until tomorrow morning. Right now I can hear the winds from the tsunami outside my window, and even though I know the waters will not reach this far inland, it is a frightening thing to be a part of one of the worst natural disasters to hit Japan in recent history.

– Photos from around Japan.

– 3:37 PST.

The Japanese government issued a state of emergency at a nuclear power plant Friday after a cooling system failure in the wake of the giant earthquake and tsunami off the east coast of the Pacific nation.

An administrator at the Tohoku Electric Power Co's Onagawa facility said the process for the cooling reactor is "not going as planned," adding that "nuclear emergency situation" has been declared. The company asked people nearby to stay calm, the official TV news channel NHK reported.

– 3:51 PST. It's as good a time as any to revisit this guide to earthquake preparation. Also, a staffer at Time Out Tokyo rounds up information for residents and offers a live blog of the afternoon.

– 4:15 PST. Twitter hashtag #HItsunami to monitor what folks in Hawaii are saying:

"These fucking sirens are making my heart stop."

"If you haven't started yet, now is the time to put down the phone/iPad/laptop and PLUG IT IN. You may need it if power goes out."

"Hard to describe feelings knowing a tsunami coming and NOTHING you can do about it."

" No going back to sleep with those sirens. I'm up. About to eat & load the car just in case."

– 4:25 PST.(The BBCWorld Twitter feed is streaming on the left margin of that page.)

BBC's Kate McGeown in Indonesia says a tsunami has been detected in the north east of the country, but it's only half-a-metre high. Too early to say if damage has been caused.

– 4:30 PST. The 15 biggest earthquakes ever recorded. Also, the WSJ reports:

TOKYOSome people in Tokyo were warned that a major earthquake was about to hit before they felt a tremor.

As an 8.9-magnitude earthquake struck Japan's northeastern coast Friday, the world's first early warning systemdeveloped by the country's meteorological agencydetected the quake's shockwave near the seismic center and sent off the warning message, which appeared on national television and radio as well as mobile phone screens.

– 4:36 PST.  AP reports official death toll is now at 60, still expected to rise significantly. Fox News has more from California:

Orange County, California is closing its beaches starting at 8 a.m. ET – and will station lifeguards and sheriffs to discourage anyone from using the beaches. At roughly 8 a.m. ET – automated calls will be going into the homes along the beach communities where officials anticipate some impact from the tsunami. Officials tell Fox News, they anticipate a surge in Orange County of about two feet.

While they don’t expect damage – the problem they anticipate has to do with tidal issues and rough surf. Large fishing boats are being encouraged to head out to sea – small boats are being urged to stay in port.

– 4:43 PST. Japanese Prime Minister Naoto Kan:

My fellow citizens, as you are already aware from reports on TV and on the radio, today at 2:46 p.m. an enormously powerful earthquake of Magnitude 8.4 struck, with its seismic center off the Sanriku coast.  This has resulted in tremendous damage across a wide area, centered on the Tohoku district.  I extend my heartfelt sympathy to those who have suffered.

As for our nuclear power facilities, a portion of them stopped their operations automatically.  At present we have no reports of any radioactive materials or otherwise affecting the surrounding areas. In light of these circumstances, I immediately established an emergency headquarters for response to disaster, with myself as the head. The government will make every possible effort to ensure the safety of the public and keep damage to the minimum possible extent. I ask the public to continue to stay fully vigilant and to keep abreast of TV and radio reports, and I ask everyone to act calmly.

– 4:45 PST. The US National Weather Service Honolulu & Central Pacific Hurricane Center is updating its Facebook page.

– 4:48 PST. A friend passes along these recommendations for japan folks to follow on Twitter: @tokyoreporter, @TomokoHosaka, @yurikageyama, @sandrajapandra, @DailyYomiuri, @daiwaka, @HirokoTabuchi

– 5:03 PST. Waves expected to hit Hawaii in the next few minutes:

Some refuge centers at schools were already filling up in the overnight hours, and lines were forming in front of convenience stores. Police combed shoreline neighborhoods, ordering evacuations and closing roads.

Officials warned that tsunami can last for hours, and attract multiple destructive waves. They also said that people were showing up at hospitals seeking shelter, and authorities urged them to go elsewhere to keep the medical facilities available for any injured people. "Anyone in the shoreline areas should get out now," he said. The evacuation area included the tourist hub of Waikiki, where thousands of people are packed into a string of beachfront hotels. Hotel guests staying in concrete or steel-reinforced buildings were being moved to the third floor for safety, Cummings said.

– 5:09 PST. An NBC affiliate in Hawaii reports that "Surf 'beginning to pick up' at Kauai, waves up to 3 feet. Water receded up to 150ft." Live coverage here. And here.

– 5:23 PST. So far so good in Hawaii on the beach cams I'm watching.

– 5:33 PST. Still no reports of serious damage as first wave recedes. Let's hope that continues.

– 5:39 PST. The Pacific Fleet reports: "At Pearl Harbor a half-meter surge was detected. Initial reports show no damage to ships and piers."