日本地震引发的海啸穿越太平洋

RENEE MONTAGNE, host: 

That earthquake is being described as the strongest one ever recorded in Japan's history. It struck offshore to the east of Japan about 80 miles from the northern coastal city of Sendai. It appears that most of the damage was caused not by the ground shaking but by the tsunami it generated, which earlier this morning reached Hawaii and is still moving across the Pacific.

Joining us to talk about all of this is NPR science correspondent Richard Harris. 

Good morning.

RICHARD HARRIS: Hi, Renee.

MONTAGNE: A magnitude 8.9, of course huge quake. What kind of damage can a quake that size cause?

HARRIS: Well, Japan was lucky, at least in terms of shaking, because this was far off the coast, and by the time the shaking came inland, it was very widespread, felt for hundreds of miles. Tokyo is 230 miles away from the epicenter of this quake. But felt over a very wide area of Japan. But according to the shaking maps that I looked at, there was no place where it was absolutely severe shaking, the kind of shaking that did so much damage in Haiti and so on.

So the shaking part of this quake, despite its size, wasn't that big wasn't as bad as it could have been, because of its distance offshore. The real issue appears to be the tsunami, which washed ashore rather rapidly. We don't know exactly how high it was. We've seen suggestions that it could be 10, 20, 30 feet tall, a very, very substantial wave coming ashore and doing great damage just by itself, the water.

MONTAGNE: And the tsunami waves are not not only big and lots of water, but (unintelligible) powerful movement, and it appears in the city of Sendai we are seeing more and more pictures, videos, coming out, looks like it just carried away, you know, buildings and cars and various things.

The death toll is in the hundreds in those areas hard hit by the tsunami. So I'm wondering how it compares to the 2004 Indian Ocean tsunami that killed hundreds of thousands.

HARRIS: Right. And in terms of magnitude, this quake was a little bit smaller than that earthquake, the major difference was that the earthquake that struck the Indian Ocean in 2004, the fault that broke over a stretch of 900 miles, and so there was a tremendous amount of movement of the earth under the ocean and a tremendous amount of movement of the water. So even though this was a very large earthquake, there's no indication right now that it was anything like that huge, huge earthquake that let(ph) so much water flowing out.

So clearly water there's enough here to create a tsunami that we've been tracking all morning across the Pacific, but it does not appear that it's going to cause anything like the kind of damage that the Sumatra earthquake did. 

MONTAGNE: And Lucy, we just heard, mentioned damage to Japan's industrial base. I gather that that base includes nuclear power plants, and what is the worry there?

HARRIS: Well, most of them just shut down safely, which is what they're supposed to do in an earthquake. But apparently one of them lost cooling water and that led Japanese authorities to declare a state of emergency there, because you need to make sure that the core stays cool, otherwise you could have a more significant, serious accident there. Right now the Japanese authorities say no radiation has escaped, but they evacuated some area around it as a priority. We're keeping a close eye on that.

MONTAGNE: And the tsumani has already hit Hawaii, in the middle of the night in Hawaii, early, 3:00, 4:00 in the morning, still dark. What do we know about that? 

HARRIS: Well, the first waves that came through were between three and six feet tall, not not that big a deal, although they aren't just like breakers on the beach.

These are actually waves. These are these can be piles of water that come in at that height. So saying a six-foot tsunami is not at all like a six-foot wave you might want to go surfing on. But that said, Hawaii did not report any significant damage. They are still waiting it out, because the first wave is not necessarily the worst one, and the all-clear has not yet been sounded in Hawaii. But it appears like this was not a huge problem there.

MONTAGNE: Which is good news for the coastlines of the USA and Central and South America, because this tsunami is headed that way too.

HARRIS: Right. And in fact, it should be arriving on the Pacific Coast even as we speak right now. And they have put up tsunami warnings for Oregon（俄勒冈(美国州名)）and California. They've warned - for Alaska - and also some warnings. And also some advisories, saying even if you're even if you're in like Washington State, don't go in the water, because the water can be very a lot of turmoil in the water.

But the expectation is the average wave will be small, but local effects can have a big difference, and you can still generate big waves in small places, so it's prudent to get to high ground.

MONTAGNE: Richard, thanks very much. 

HARRIS: My pleasure. That's NPR's science correspondent Richard Harris.