SPEAKER_1: Welcome to StarTalk, your place in the universe, where science and pop culture collide.
SPEAKER_1: StarTalk begins right now.
SPEAKER_1: Welcome back to StarTalk Radio.
SPEAKER_1: I'm your host, DeGrasse Tyson.
SPEAKER_1: I'm an astrophysicist and director of New York City's Hayden Planetarium.
SPEAKER_1: This week, we have a special edition of StarTalk, where we focus on the violent Earth.
SPEAKER_1: Earthquakes.
SPEAKER_1: Volcanoes.
SPEAKER_1: Tsunamis.
SPEAKER_1: We want to give you the science that enables us to understand and interpret the reports we've been getting from the Pacific Rim.
SPEAKER_1: On March 11th, Japan was hit by a triple punch, a 9, 8.9 magnitude earthquake, a tsunami that followed shortly after, and one of the scariest among natural disasters that you might imagine.
SPEAKER_1: The concern about a nuclear power plant right there on the coast damaged by the tsunami and the earthquake is at risk of meltdown.
SPEAKER_1: We'll address a science behind each of these issues, and over the course of the show, we will bring in experts to find out and get to the bottom of what's going on in the science of the earth.
SPEAKER_1: I'm joined this week by my colleagues at the American Museum of Natural History.
SPEAKER_1: One is a friend I've, for decades, Steve Soder.
SPEAKER_1: He's an astrophysicist.
SPEAKER_1: Steve, welcome to StarTalk Radio.
SPEAKER_1: Thank you.
SPEAKER_1: Yeah, and he happens to be an expert on earth phenomenon as well as tsunamis throughout history.
SPEAKER_1: And I've also got Jim Webster.
SPEAKER_1: He's a geologist in the Department of Earth and Planetary Sciences, and he has a specialty in volcanoes.
SPEAKER_1: Jim, welcome to StarTalk Radio.
SPEAKER_2: Thank you, Neil.
SPEAKER_2: It's great to be here.
SPEAKER_1: Thanks for coming on, and I want to just start with you, Jim.
SPEAKER_1: You're the geologist here, and so we all get to kind of blame you for these phenomena.
SPEAKER_1: Can you tell me what an earthquake is and why we have them, and what's going on with the Earth?
SPEAKER_2: An earthquake is a release of energy in the outer portion of our planet.
SPEAKER_1: So the energy's gotta come from somewhere.
SPEAKER_1: Now, I know how to form a solar system.
SPEAKER_1: Well, I know how to describe the formation of a solar system.
SPEAKER_1: You start with a huge gas cloud.
SPEAKER_1: It's mostly hydrogen and helium, and there's a little bit of trace elements elsewhere.
SPEAKER_1: It forms a sun in the middle, and you have these other concentrations of mass that make the planets.
SPEAKER_1: And each of those planets will have some leftover heat.
SPEAKER_1: Some of the heat is because it was hot when it formed.
SPEAKER_1: Others because as it collapses, it gets hotter for having collapsed.
SPEAKER_1: And Earth is still hot.
SPEAKER_1: It seems to me 4.5 billion years should be long enough for this place to have cooled down.
SPEAKER_1: What's going on?
SPEAKER_2: Well, I like the fact that you focused on heat and energy, because really it's this release of energy that drives seismic or earthquake activity.
SPEAKER_2: And it's also what, hopefully, we'll talk about a little bit later, the volcanoes that are associated with earthquakes around our planet.
SPEAKER_2: Early on in the formation of our planet, there was the accretion energy of the various particles literally slamming into one another violently and generating heat energy.
SPEAKER_1: So if you have energy of motion, and then you stop moving because you collided, that energy still has to go somewhere, and it's revealed in the heat of the object.
SPEAKER_2: So it starts heating this object, but the objects would grow over time.
SPEAKER_2: And eventually the body was large enough and heavy enough that the more dense materials, iron, nickel, metal, alloys, started sinking to the center under the force of gravity.
SPEAKER_1: So you need a fluid object for this to happen.
SPEAKER_1: Otherwise it'll just sit on the top as a rock.
SPEAKER_1: But the earth at that time was liquidy enough, plasticky enough for heavy things to fall and light things to rise.
SPEAKER_1: That's what you're saying.
SPEAKER_2: Well, again, I love your choice of language because the word fluid may or may not be a liquid.
SPEAKER_2: I mean, a hot solid material, if it's hot and it behaves slowly over a very long period of time, it will behave as a fluid.
SPEAKER_1: It's not in a fluid and in a conventional sense, but given enough time, it'll move.
SPEAKER_2: Exactly, or materials may move through it.
SPEAKER_1: May move through it.
SPEAKER_1: So if you're heavy, you fall to the middle.
SPEAKER_1: So this is a way you segregate out heavy from light in the formation of the earth.
SPEAKER_2: And we know that the core of our planet is largely iron nickel.
SPEAKER_2: And it was the formation of that core that also generated a tremendous amount of energy that still resides, part of it still resides in our planet.
SPEAKER_1: Still resides.
SPEAKER_1: And so that energy manifests itself by violent activity on earth's crust.
SPEAKER_2: Exactly, the most apparent thing for us is perhaps watching volcanic eruptions at surface, molten material being issued forth.
SPEAKER_1: This is kind of a peek into the innards of the earth.
SPEAKER_1: The earth is revealing its insides.
SPEAKER_2: Exactly, and that's one of the few ways, one of the better ways that we can actually gather materials from the inner earth because they're carried up by molten lava to the surface.
SPEAKER_1: So, volcanoes aren't just anywhere.
SPEAKER_1: I tend to see them collected where you've got sort of, where you also find earthquakes, right?
SPEAKER_1: And so, these are related phenomenon, clearly.
SPEAKER_2: Exactly, not to get too heavy into plate tectonic theory, but the surface of our planet consists of these brittle plates that float around this fluid, not liquid, but fluid medium.
SPEAKER_2: And in fact, it's where these plates converge and where they come apart, it really represents the great majority of the earthquake activity on our planet and the great majority of the volcanic activity, molten rock.
SPEAKER_1: So, one of the most famous regions would be, what I've read about is called the Ring of Fire, which is basically the entire perimeter of the Pacific Ocean, isn't that correct?
SPEAKER_2: Exactly, if you want to start in the western portion of the Pacific and move up from New Zealand up to the various island chains along the western coast, excuse me, the eastern coast of Asia, and then up around the corrals, the Aleutians to the north.
SPEAKER_1: The Aleutians of Alaska and come right on down the west coast of the North America.
SPEAKER_2: North and South America.
SPEAKER_1: And South America, right on down to Tipi Chilli.
SPEAKER_2: And more than 400 active volcanoes around that ring.
SPEAKER_1: And this is what we call the Ring of Fire.
SPEAKER_2: Exactly.
SPEAKER_1: So when there's a volcano erupting or an earthquake in that zone, we shouldn't be surprised.
SPEAKER_2: No.
SPEAKER_1: Not at all.
SPEAKER_2: Business as usual.
SPEAKER_1: Business as usual for Earth.
SPEAKER_1: So what kind of, I have a tweet from someone, let's say if you read the tweet, tweet names are always fascinating here.
SPEAKER_1: Just call them Stuber.
SPEAKER_1: Why is it so hard to predict earthquakes when we know so much about plate tectonics?
SPEAKER_1: Because you sound knowledgeable.
SPEAKER_1: What's the problem here?
SPEAKER_2: Earthquakes are due to a very localized phenomenon in the upper portions of our planet.
SPEAKER_2: It may impact the larger areas.
SPEAKER_1: The crust, you mean the crust with the upper portions.
SPEAKER_2: The crust and then earthquakes actually are sourced in the mantle.
SPEAKER_2: That region.
SPEAKER_1: Deep down.
SPEAKER_2: That fluid portion below the brittle crust of our planet, yes, earthquakes can start there as well.
SPEAKER_2: But there are localized phenomenon to start and to actually be able to predict at any given point in time, what's going to happen in the immediate future becomes difficult.
SPEAKER_1: So you can predict sort of statistically how many earthquakes you might expect in a zone or in a region, but for a specific spot, a city, a town and a date, you can't provide that just yet.
SPEAKER_2: Without precursory information, exactly.
SPEAKER_2: That's what makes it difficult.
SPEAKER_1: Precursory information.
SPEAKER_1: That sounds like the information you haven't figured out how to get yet, is that?
SPEAKER_2: Well, that's what earth scientists and others are trying to acquire and try to interpret to look for correlations between some precursor phenomenon.
SPEAKER_1: Okay, so we have earthquakes and now there's a scale that we use to measure them.
SPEAKER_1: When I grew up, they called it the Richter scale, but now it seems to be called something different.
SPEAKER_1: Steve Soder studied earthquakes throughout history and as they've affected cultures and civilizations.
SPEAKER_1: So what's the scale we're using today?
SPEAKER_3: Well, it's called the Moment Magnitude Scale.
SPEAKER_3: The old Richter scale could not measure earthquakes that were of the highest magnitudes accurately.
SPEAKER_1: Didn't really-
SPEAKER_1: So the scale was ineffective?
SPEAKER_3: It was ineffective at that.
SPEAKER_1: At distinguishing really high magnitude from even higher magnitude earthquakes.
SPEAKER_3: Correct, and so a new magnitude scale based on what's called moment magnitude was devised in the 1970s.
SPEAKER_3: And that involves three factors.
SPEAKER_3: One is the area of the fault that breaks.
SPEAKER_3: A second is the slip along that fault.
SPEAKER_1: How far it moves.
SPEAKER_3: How far it moves.
SPEAKER_3: And the third is the rigidity of the rock.
SPEAKER_3: How strong the rock is.
SPEAKER_1: So you can actually quantify the rigidity.
SPEAKER_1: So two extremes of rigidity, one might be rubber and another extreme might be diamond, let's say.
SPEAKER_3: Yes, and those things can all be measured more or less for all earthquakes.
SPEAKER_1: And so you come up with numbers and now the numbers seem pretty simple.
SPEAKER_1: It's like one to 10 or something, but is there a limit to the scale?
SPEAKER_3: Well, actually it's a logarithmic scale, which means that each number, going from a magnitude, say seven to eight, is not a small change in energy.
SPEAKER_3: It turns out to be a change of a factor of about 33 for each magnitude.
SPEAKER_1: For each magnitude.
SPEAKER_3: Yes, so if you go up two magnitudes, it's 33 times 33, which is a thousand.
SPEAKER_3: In terms of the amount of energy which is released.
SPEAKER_3: So for example, the earthquake that just struck Japan was a magnitude nine.
SPEAKER_3: The earthquake that struck in Haiti was a magnitude seven.
SPEAKER_3: The difference in the energy was a factor of a thousand.
SPEAKER_1: Factor of a thousand.
SPEAKER_1: And so if you look at earthquake magnitude scales, the last numbers I saw for Japan were 8.9.
SPEAKER_1: I want to so round that to nine.
SPEAKER_3: It has been rounded by the US Geological Survey to nine.
SPEAKER_1: It has been rounded to nine, okay.
SPEAKER_1: So that's good.
SPEAKER_1: So, I mean, not good, I mean, it's useful.
SPEAKER_3: Simplifies.
SPEAKER_1: Simplifies how we think about this.
SPEAKER_1: So that's interesting to know about the magnitude of that quake versus other quakes that we know about.
SPEAKER_1: And when I think about it, what's the limit of quake power on the scale?
SPEAKER_3: It has to do with the size of the fall.
SPEAKER_1: Because I once got a tweet from someone, is it in this batch here?
SPEAKER_1: I'm looking at my notes here.
SPEAKER_1: The, yeah, who is this?
SPEAKER_1: Someone named Corbett asked, I keep getting asked, would a 10.0 earthquake end the world?
SPEAKER_1: Because we've never had a 10.0 earthquake.
SPEAKER_1: It might be worth touching on, as millions are predicting no Christmas after that one.
SPEAKER_3: Well, the largest recorded earthquake was a 9.5 that was in Chile in 1960.
SPEAKER_1: It's basically modern times, isn't that a historical thing?
SPEAKER_3: It's only in modern times that we've been able to measure these things, to quantify these things with any degree of accuracy.
SPEAKER_1: Back to what year?
SPEAKER_3: Oh, about 1900 probably.
SPEAKER_1: Back to 1900, okay.
SPEAKER_1: So that's a century of data we have going for us.
SPEAKER_1: All right, so you had a 9.5, where was it again?
SPEAKER_3: That was along the coast of Chile, South America.
SPEAKER_1: Here we are, Jim Webster in the Ring of Fire again.
SPEAKER_2: Exactly.
SPEAKER_1: All right, so Steve, continue.
SPEAKER_3: Okay, well, that earthquake was the largest that was measured instrumentally.
SPEAKER_3: How large could an earthquake be?
SPEAKER_3: It depends on the length of the fault.
SPEAKER_3: And faults cannot be indefinitely large.
SPEAKER_3: For one thing, it cannot be larger than the Earth.
SPEAKER_1: Than a circle around the Earth.
SPEAKER_3: Right, but just hypothetically, suppose that you consider the circumference of the entire Earth as a fault, and you made a slip across that, that had the size of the slip of a very large earthquake, and we know the rigidity of the Earth.
SPEAKER_3: If you put those numbers together, you would get a hypothetical earthquake of magnitude 12.
SPEAKER_3: I mean, that would be the extreme upper limit.
SPEAKER_1: Of course, that'd be a really bad day on Earth.
SPEAKER_3: Yes, but of course, it's totally unrealistic because there's no way that you could have a break along a fault that wrapped entirely around the Earth.
SPEAKER_1: Now, if you start, so earthquakes, it seems to me, could, Jim, my resident geologist now, earthquakes ought to be able to trigger a volcano, is that correct?
SPEAKER_2: You know, that's an excellent question because for years at the museum, we would hear these questions posed by the public, and honestly, initially, folks would scoff at the likelihood that there was some reaction between seismic.
SPEAKER_1: When you say folks, you mean your colleagues of another era?
SPEAKER_2: Unfortunately, yes.
SPEAKER_2: Okay.
SPEAKER_1: Be specific.
SPEAKER_2: Well, I don't want to embarrass my colleagues, but yes, that was the typical response.
SPEAKER_2: But in the last several decades, we've seen data that seemed to imply strongly that there can be relationships, causal relationships.
SPEAKER_2: For example, after this earthquake that Steve was talking about in Chile in 1960, within 38 hours, there was a major eruption at Cordon Calais, about 380 kilometers away.
SPEAKER_1: 380 kilometers is not far given the size of these plates.
SPEAKER_2: Exactly.
SPEAKER_1: Now in Japan, Fujiyama is a volcanic cone, isn't that correct?
SPEAKER_2: Mount Fuji, yes.
SPEAKER_1: Mount Fuji, yes.
SPEAKER_1: And so, any chance that this earthquake will stimulate Fujiyama back into an explosion?
SPEAKER_1: Because when did Fujiyama last explode, do you remember?
SPEAKER_3: I believe it's 1700, do you know that?
SPEAKER_1: 1707, so any chance of that happening again?
SPEAKER_2: Probably a very slight chance, not to worry the inhabitants of Japan that they're yet to suffer another tragedy, but potentially if there is magma sitting in Fuji charged with gases waiting for some trigger, this could potentially provide a trigger.
SPEAKER_1: If it were primed for that trigger.
SPEAKER_2: Exactly, it would require that.
SPEAKER_1: If it's not primed, it's just another day in the life of a dormant volcano.
SPEAKER_1: After the break, we'll talk about what effect, if any, the universe has on the Earth.
SPEAKER_1: Thanks Bye We're back to StarTalk, I have two special guests in the studio with me on this special StarTalk program where we're focusing on the violent earth and what it's done to us in the past, what it might continue to do to us in the future, with special attention of course to the earthquake in Japan.
SPEAKER_1: Joining with Steve Soder, he's an astrophysicist, a long time friend and colleague of mine, and Jim Webster, a geologist specializing in volcanoes, both of whom from the scientific departments of the American Museum of Natural History.
SPEAKER_1: Jim, I hand you your elements that you work with.
SPEAKER_1: You're actually a geochemist specifically, right?
SPEAKER_2: I'm a geochemist on the mineral deposits curator at the museum.
SPEAKER_1: Mineral deposits, and so I can give you these minerals from the formation of the earth.
SPEAKER_1: The base elements that make your minerals are part of the gas cloud that forms the solar system, and they don't really segregate out until we have this molten blob that would one day become earth.
SPEAKER_1: Heavy things sink to the bottom, light things sink to the top, and over the break, you were telling me about what goes on on earth to get these heavy elements out from the lower regions to the surface, where we can then mine them as ore.
SPEAKER_1: So what is that process?
SPEAKER_2: Well, in the context of our violence, our active or dynamic earth, it's not only earthquakes and volcanoes that are a consequence of energy from its interior, but these magma or molten bodies actually heat water.
SPEAKER_2: The water dissolves trace concentrations of metals like gold or silver or copper and many others, moves them and deposits them in fractures, forming vein deposits in the crust of our planet.
SPEAKER_1: So this is where we get these ores.
SPEAKER_2: They're beneficial to us, absolutely.
SPEAKER_1: When I see a vein that is iron or gold or platinum, that used to be running water through that rock.
SPEAKER_2: A great many of them, yes, because we know from just washing clothes at home, hot water is a better solvent.
SPEAKER_2: It does a better job of cleaning, very hot water in the interior of our planet and the crust of our planet dissolves metals.
SPEAKER_1: It does such a good job of cleaning, it cleans off the color from your clothes as well.
SPEAKER_1: Exactly.
SPEAKER_1: And so, not only have there been concerns about what's going on with Earth, there's been a lot of sort of misinformation, even pseudoscience regarding the forces of the universe and whether they had some effect on the earthquake itself.
SPEAKER_1: For example, there was a report, dare I say it was even advanced by a meteorologist suggesting that something called a supermoon might have had special influence on Earth's crust triggering the Japanese earthquake.
SPEAKER_1: And a supermoon by that terminology would be a moon in its orbit around the Earth, which is elliptical, sometimes closer to Earth, sometimes farther away.
SPEAKER_1: A more colloquial term for that would be oval.
SPEAKER_1: So when the moon is very close, it has stronger tidal forces.
SPEAKER_1: So the tides that we all know and love at the beach, these forces are operating and are related to the moon's distance from us.
SPEAKER_1: But they're also related to the phase of the moon.
SPEAKER_1: Full moon and new moon have high tides.
SPEAKER_1: Quarter moons give you the neap tides where the moon is actually competing for the sun for who's gonna raise the water and the water doesn't get raised at all.
SPEAKER_1: So if you combine full moon, new moon, with when it's closest, you get sort of a double effect.
SPEAKER_1: And there was worry and concern that the super moon might have caused this.
SPEAKER_1: The problem was, for that concept, is that the earthquake took place during quarter moon.
SPEAKER_1: So it's not even a full moon.
SPEAKER_1: You're not even combining that.
SPEAKER_1: And the super moon that anyone would have referred to took place on March 19th.
SPEAKER_1: And March 19th is, okay, so you have full moon.
SPEAKER_1: You'll have a close moon.
SPEAKER_1: If you look at the data, we have a lot of data on full moons in the history of the world.
SPEAKER_1: We know the moon's orbit from Newton's laws.
SPEAKER_1: You go back through time and you just correlate this with where and when earthquakes might have happened.
SPEAKER_1: And Steve Soder, what do we find?
SPEAKER_3: There's no correlation.
SPEAKER_1: There is, there's no correlation.
SPEAKER_3: People have been looking for it for a long time to see if there's any correlation between the occurrence of earthquakes and the lunar orbit and the tides, and there's nothing significant.
SPEAKER_1: And it's simply not there.
SPEAKER_1: And so people might say, well, it's gotta have some effect.
SPEAKER_1: And what I always then tell them is, if it has any effect at all, what you really wanna do is compare it with other things that might have an effect that swamps it, allowing you to completely ignore these other phenomena.
SPEAKER_1: And so when you look at other factors that can affect what's going on in the earth, for example, Jim, beneath the crust, there's this gurgling convection moving magma all the time.
SPEAKER_2: In the mantle, that portion of the planet just below the crust that's fluid, most of it is not liquid, it's solid, but over geologic time, hundreds of millions of years, it's slowly moving, but it's driving the motions of the plates at the surface and leading to magma forming at the crust and volcanoes erupting, and again, most of our seismicity.
SPEAKER_2: But can I ask you a question?
SPEAKER_1: Yeah, sure, sure.
SPEAKER_2: And as you're talking about the fact of tides, we know that earth tides, the attraction of the moon, actually causes our planet to expand and contract roughly a meter.
SPEAKER_1: Yeah, not only the liquid contents of the earth, the oceans, but also the physical earth expands about a meter every time you go through high tide.
SPEAKER_1: That's correct.
SPEAKER_1: This is happening all the time twice a day.
SPEAKER_1: Twice a day.
SPEAKER_2: And still we have no correlation with seismic activity.
SPEAKER_1: No correlation, that's correct.
SPEAKER_1: Because we have two high tides a day, two low tides a day.
SPEAKER_1: That you think, by the way, just by the way, in the solar system, there are places where tides are totally wreaking havoc on their host objects.
SPEAKER_1: For example, tides from Jupiter are squeezing and pumping energy into the nearby moons to Jupiter.
SPEAKER_1: Io is one of them, Europa is another.
SPEAKER_1: These moons are much, much hotter for the effects of the tidal forces.
SPEAKER_1: In fact, surely you know, Jim, that the most active volcano in the solar system is Jupiter's moon Io.
SPEAKER_1: It's got volcanoes there, and where is it getting its heat?
SPEAKER_1: It's a tiny little object.
SPEAKER_1: It's getting pumped by the tidal forces of Jupiter.
SPEAKER_2: They have unusual volcanoes, sulfur-emitting volcanoes on Io.
SPEAKER_1: You don't want to be there for that, right?
SPEAKER_1: And so the point is, Steve, then if there were a correlation, it would have easily revealed itself in the data because we have centuries, millennia of data of earthquakes and lunar phases.
SPEAKER_1: So I just want to dispel that myth.
SPEAKER_1: Whether or not it has happened or can happen, elsewhere, our moon doesn't do it to Earth.
SPEAKER_3: That's correct.
SPEAKER_1: Period.
SPEAKER_1: Okay, so not only that, we have people concerned about what effect the earthquake has on our axis.
SPEAKER_1: And that's a fun one.
SPEAKER_1: It's fun to calculate that, Steve.
SPEAKER_1: So what can you tell us there?
SPEAKER_3: Well, when there is a major earthquake and the motion of plates, there's a displacement.
SPEAKER_1: Steve is motioning with his hands.
SPEAKER_1: It's kind of cute.
SPEAKER_1: It's like a little dance thing here, okay.
SPEAKER_3: But there's a slight redistribution of the mass of the Earth.
SPEAKER_3: It's very slight on the scale of the entire Earth.
SPEAKER_3: But it's enough to make a change, a very small change in the length of day and the tilt of the Earth's axis.
SPEAKER_3: But they're really trivial.
SPEAKER_3: They're nothing that you would notice or would have any consequences of practical.
SPEAKER_1: Because I've got a question here.
SPEAKER_1: There's another tweet that said, is it common for large earthquakes to change Earth's axis and will the Earth correct itself or is each change permanent?
SPEAKER_1: That's a great question.
SPEAKER_3: Well, the changes are random and so they act in different directions.
SPEAKER_3: They won't correct themselves, but it is common.
SPEAKER_3: It's just that the effects are extremely small.
SPEAKER_1: So if they're random, it means some earthquakes can speed up the rotation of the Earth and others can slow them down.
SPEAKER_1: So the net effect might just be nothing over a long enough baseline of time.
SPEAKER_1: And so the actual basis of that phenomenon is that your rotation rate is related to how the mass is distributed in your body.
SPEAKER_3: It's like an ice skater, meaning holding weights at arm's length.
SPEAKER_1: And in their case, their weights are just the weights of their hands.
SPEAKER_3: Right.
SPEAKER_3: Pulling them in slightly.
SPEAKER_1: They're changing the distribution of their mass.
SPEAKER_3: So you spin up.
SPEAKER_1: They spin up.
SPEAKER_3: To conserve angular momentum, as it's called.
SPEAKER_3: And the Earth can do the same thing.
SPEAKER_1: And so plates start moving.
SPEAKER_1: So Jim, plates move over each other, under each other, sideways to each other.
SPEAKER_2: Well, in the process of subduction, the more dense but thinner ocean crust.
SPEAKER_1: That's an actual word, subduction.
SPEAKER_2: Subduction.
SPEAKER_1: Sounds very X-rated.
SPEAKER_2: Geo jargon.
SPEAKER_1: Geo jargon, go for it.
SPEAKER_2: But the ocean crust, because it's more dense and thinner, is actually thrust or subducted beneath nearby continental crust.
SPEAKER_1: And so you're changing the distribution of mass on the Earth.
SPEAKER_2: You're changing distribution of mass.
SPEAKER_1: So it has to either speed up or slow down in response to that.
SPEAKER_2: So in the case of the Japanese earthquake, Japan moved towards the east about eight feet, and it was in the same direction that the Earth was spinning, correct?
SPEAKER_2: So that's why the Earth is spinning up.
SPEAKER_1: Well, actually, it would relate to whether mass moved towards the pole or away from the pole, because then that's where you're getting closer to the rotation axis or farther away.
SPEAKER_1: So then, so this would be the, the, the, the, the discussion.
SPEAKER_1: So we can ask, how much of an effect did this have?
SPEAKER_1: And so, Steve, what was...
SPEAKER_3: It's negligible.
SPEAKER_1: That's your quanti-
SPEAKER_1: how you quantify it.
SPEAKER_3: Yes, of no practical consequence whatsoever.
SPEAKER_1: Of no practical consequence.
SPEAKER_1: It is true, however, that we track and monitor the rotation rate of the Earth.
SPEAKER_1: The tides raised on our surface by the moon, the sloshing of these tides back and forth on our continental shelves creates friction and actually slows down the rotation of the Earth.
SPEAKER_1: Systematically, so in fact, we've had to add, what, we're up to 23 or so leap seconds added to the calendar to compensate for our slowing down simply because of the tides.
SPEAKER_3: The day is getting longer because of the tides.
SPEAKER_1: The day is getting longer, and that's been going on forever.
SPEAKER_3: Since the moon was there.
SPEAKER_1: So here's another quick question in just the couple of minutes we have left before our next break.
SPEAKER_1: If we drill into the Earth's crust, pulling out oil and ore and replacing it with water, what effect does that have on the stability of the crust, Jim?
SPEAKER_2: That has no real effect.
SPEAKER_2: We do know that there's subsidence in places like the Phoenix area, where groundwater is withdrawn, has caused local areas of collapse and this very local, very shallow levels of collapse.
SPEAKER_1: Collapse of land.
SPEAKER_2: And land, but not in the larger plate tectonics, large crustal process.
SPEAKER_1: But Steve, wasn't there some plate, some measured earthquake levels from this activity?
SPEAKER_3: Well, there was injection of fluids into the crust of the Earth in, I think Colorado in the 1960s that began to trigger lots of small earthquakes and when they stopped.
SPEAKER_1: Small would be on what level?
SPEAKER_3: Oh, magnitude four, something like that.
SPEAKER_1: Four, so Jim, magnitude four, do you even feel that?
SPEAKER_1: I remember when the World Trade Center collapsed, I lived nearby them.
SPEAKER_1: I made careful notice of what it felt like as they collapsed.
SPEAKER_1: It was about on the level of a subway rumbling underfoot.
SPEAKER_1: And then I read the earthquake scale, 4.5 is about that.
SPEAKER_1: It'll rattle your dishes a little bit.
SPEAKER_1: There's no ever any damage.
SPEAKER_2: That's about right.
SPEAKER_2: So it was the lubrication of these fluids being injected in Colorado along the fault surface that allowed the slippage to increase and cause these small earthquakes.
SPEAKER_1: So what you're saying is that if you have friction, holding it together and then you start-
SPEAKER_2: Locking them up.
SPEAKER_1: It's basically locked by friction.
SPEAKER_3: You're weakening the fault when you inject a fluid into it.
SPEAKER_1: You're lubricating the fluid.
SPEAKER_3: Exactly.
SPEAKER_1: You're lubricating the fault.
SPEAKER_1: And so you can actually trigger earthquakes by this method.
SPEAKER_2: Yes.
SPEAKER_1: That's amazing.
SPEAKER_1: We're gonna have to get back to that in the fourth segment, but in the third segment, we'll go straight to my interview, which I had this afternoon with nuclear physicist, Michio Kaku, to talk about Japan's nuclear power plant and the disaster risks involved.
SPEAKER_1: We'll see you at the end of the day.
SPEAKER_1: Bye StarTalk Radio, our special Violent Earth Edition, inspired by the tragic earthquake and tsunami in Japan.
SPEAKER_1: We're gonna go straight to my interview with Michio Kaku, Professor of Physics at the City University of New York, to chat about Japan and the nuclear risk that are posed by the reactors.
SPEAKER_1: Check it out.
SPEAKER_1: So Michio, when we think of nuclear power, there's fusion, there's fission, but all power plants in the world are fission, right?
SPEAKER_4: That's right.
SPEAKER_4: Fusion power is the engine of the universe.
SPEAKER_4: It's what drives the stars, the galaxy, all of it because we fuse hydrogen to create helium.
SPEAKER_4: But on the earth, as far as we can tell, only on the earth do we use uranium.
SPEAKER_4: So instead of fusing the atoms of hydrogen, we split the atom of uranium.
SPEAKER_4: Now believe it or not, mother nature does not use fission.
SPEAKER_4: Only in bombs and nuclear power plants do we use fission.
SPEAKER_1: In the whole universe.
SPEAKER_4: Could be.
SPEAKER_4: There's only one naturally occurring reactor that we think can go back to paleo times.
SPEAKER_4: But other than that, we see no example of a naturally occurring fission process.
SPEAKER_1: So we know of all these sort of bad byproduct of fission, and this is the physics of the nuclear bombs.
SPEAKER_1: So why don't we just use fusion?
SPEAKER_1: Is it because we don't know how to control it yet?
SPEAKER_4: Well, it's relatively easy to create a fission plant because uranium will split up all by itself.
SPEAKER_4: So you do nothing, and then you can get a fission process going.
SPEAKER_4: Of course you have to purify it.
SPEAKER_4: Fusion on the other hand, you have to concentrate with enormous pressures and temperatures to get the fusion process going.
SPEAKER_4: That's why Mother Nature can do it because gravity is for free in outer space.
SPEAKER_4: Hey, you get gas, you compress it, boom, bingo.
SPEAKER_4: You got a star.
SPEAKER_4: When I was in high school, by the way, my advisor was one of the founders of this nuclear energy, Edward Teller.
SPEAKER_4: Nuclear energy, he said, does not belong on the surface of the earth.
SPEAKER_4: It belongs underground.
SPEAKER_4: Because if it's underground and you have a tsunami, you simply put the manhole cover on it and walk away.
SPEAKER_4: Now the fundamental difference between fusion and fission as far as health and safety are concerned is that fusion is clean.
SPEAKER_4: Helium gas is actually commercially valuable.
SPEAKER_4: Hydrogen to helium, very clean, very little nuclear waste.
SPEAKER_1: Helium is the byproduct of fusion going on in the sun every day of the week.
SPEAKER_4: But fission creates fission products.
SPEAKER_4: In other words, you split the uranium atom, you get cesium, strontium, iodine, all the radioactive products that come spewing out of a nuclear accident.
SPEAKER_1: And these very same chemicals can be absorbed into the body in bad ways.
SPEAKER_4: That's right.
SPEAKER_4: Take a look at the thyroid gland.
SPEAKER_4: The thyroid gland can absorb iodine-131 with a half-life of eight days and give you thyroid cancer.
SPEAKER_4: In fact, thyroid cancer was one of the main byproducts, health byproducts of the Chernobyl accident.
SPEAKER_4: People drank milk, iodine occurs in water-soluble form, gets into the milk, concentrates in the thyroid gland.
SPEAKER_4: Strontium-90 concentrates in the bone marrow.
SPEAKER_4: And cesium-137 will concentrate throughout the body.
SPEAKER_4: The half-life of strontium and cesium are about 30 years.
SPEAKER_4: And that means that if you ingest this into your bones and your muscle, your body will become radioactive and will be radioactive for centuries.
SPEAKER_4: Long after you're dead, your grave will be radioactive.
SPEAKER_1: Japan is no stranger to national disaster.
SPEAKER_1: They have been in an earthquake zone ever since the culture set foot there.
SPEAKER_1: There's also, of course, the nuclear bomb blast from 1945.
SPEAKER_1: And there's no shortage of the films that show Godzilla and other sort of creatures leveling cities.
SPEAKER_1: So can you comment on how well Japan is taking this?
SPEAKER_4: In the Japanese language, we have something called gaman, that is, suffer quietly.
SPEAKER_4: And that's what they've done throughout their history.
SPEAKER_4: In 1923, the entire city of Tokyo was leveled.
SPEAKER_4: 140,000 people died in that massive Kanto earthquake.
SPEAKER_4: And yeah, you live with it.
SPEAKER_4: Every time I go to Tokyo, you kind of feel the earth shake underneath your feet.
SPEAKER_4: And so you realize that even though we have satellites in outer space and we can see in outer space, we cannot even see an inch below your own feet.
SPEAKER_4: You can't predict them.
SPEAKER_4: There's no way to X-ray the earth.
SPEAKER_4: And as a consequence, we're children when it comes to predicting earthquakes.
SPEAKER_1: My view on this is the disasters thus far doesn't seem to be much worse than anything that's happened before, such as in Chernobyl.
SPEAKER_1: Is this a day to celebrate how safe Japan has made itself in the face of what it knew would be ultimate disasters?
SPEAKER_4: Well, some people think that the situation is, quote, stable.
SPEAKER_4: Well, that's like hanging in there on a cliff on your fingernails.
SPEAKER_4: Yes, it's stable.
SPEAKER_4: But if your fingernails start to break or start to get tired, you are toast.
SPEAKER_4: And so that's the situation here that as long as the radioactive byproducts don't penetrate the containment, then you're okay, like Three Mile Island.
SPEAKER_4: Three Mile Island was the class five accident.
SPEAKER_4: 90% of the core disintegrated, but the vessel held the radioactive material.
SPEAKER_1: The vessel intended to do that by design.
SPEAKER_4: That's right.
SPEAKER_4: In fact, the rods, which are very clean and vertical, looks like a box.
SPEAKER_4: At Three Mile Island, when they opened up the reactor to photograph the state of the core, they found that it looked like a bowl of granola, totally fragmented and disintegrated.
SPEAKER_1: But nonetheless contained.
SPEAKER_4: But contained.
SPEAKER_4: Now, we think that this accident is class six, in the sense that it's contained but seeping out.
SPEAKER_1: Not explosively, but just through...
SPEAKER_4: Steam explosions and hydrogen gas explosions.
SPEAKER_4: Zirconium interacts with water to create hydrogen gas.
SPEAKER_4: You light a cigarette, you light a switch, and boom, you have hydrogen gas explosion.
SPEAKER_4: Now, we had three of them in Japan.
SPEAKER_1: Many people thought those explosions were radioactive.
SPEAKER_4: It was a chemical explosion.
SPEAKER_4: But it blew the roof right off the containment structure.
SPEAKER_4: And at Chernobyl, we had a class seven accident, an accident that ruptured not just the core, not just the vessel, but the building itself, and shot about 25% of the fission products right into the air, into people's backyard.
SPEAKER_1: And all I'm saying is that at Chernobyl, it was unprovoked by nature.
SPEAKER_4: Right, and Chernobyl, it was human error.
SPEAKER_4: People disengaged the scram safety mechanism.
SPEAKER_1: And meanwhile, in Japan, that plant's been around since the early 70s, right?
SPEAKER_4: That's right.
SPEAKER_4: It's a very old 1971 design, the Mark I General Electric boiling water reactor.
SPEAKER_1: So why doesn't the reactor just cool down all by itself?
SPEAKER_1: What is driving the heat source that puts it at risk of melting?
SPEAKER_4: A nuclear meltdown is forever, in the sense that you have all this nuclear waste.
SPEAKER_4: Once you shut off the chain reaction, power is reduced by 90%.
SPEAKER_4: But it's that last 10% of power that lasts for tens of thousands of years.
SPEAKER_4: And that causes the meltdown.
SPEAKER_4: It's called decay heat.
SPEAKER_4: Decay heat very slowly goes away.
SPEAKER_4: But that decay heat, the 10% of the original power is enough to melt the containment, is enough to blow the entire reactor apart.
SPEAKER_4: And we saw that at Chernobyl.
SPEAKER_1: So this is the heat that it would generate on its own.
SPEAKER_4: Right.
SPEAKER_4: People say, well, why don't they simply hit the off switch?
SPEAKER_4: Right?
SPEAKER_4: Why don't they simply turn it off?
SPEAKER_4: You cannot turn off Mother Nature.
SPEAKER_4: You cannot turn off nuclear fission.
SPEAKER_4: So once you scram the rods, that is you stop the chain reaction, decay heat keeps on going for an extended period of time at Chernobyl.
SPEAKER_4: Do you know that it's still hot at Chernobyl?
SPEAKER_4: That was a 1986 explosion.
SPEAKER_4: When it rains, water seeps into the sarcophagus of concrete, heats up, the chain reaction slowly builds up again.
SPEAKER_1: Water is an excellent source of coolant.
SPEAKER_1: So what's the problem?
SPEAKER_1: There's no shortage of water, obviously, especially in the face of a tsunami.
SPEAKER_4: Think of driving a car.
SPEAKER_4: The car is out of control.
SPEAKER_4: What do you do?
SPEAKER_4: You hit the brakes, but the brakes don't work.
SPEAKER_4: Then the radiator starts to overheat and the radiator explodes.
SPEAKER_4: So your brakes don't work, the radiator explodes, and then your gas tank is about to catch on fire.
SPEAKER_4: What do you do?
SPEAKER_4: You head for the river.
SPEAKER_4: The river will cool down the car, cool down the radiator and make sure that you don't explode.
SPEAKER_4: Well, that's what's happening at the reactor site.
SPEAKER_4: First, the emergency core cooling system didn't work because the tsunami knocked it out.
SPEAKER_4: No brakes.
SPEAKER_4: Then hydrogen gas bubble blew up the containment structure, blowing up your radiator.
SPEAKER_4: And then what they do, they pump seawater into the reactor site.
SPEAKER_1: Next best thing available.
SPEAKER_4: Right, like driving it into the river.
SPEAKER_4: But the problem is that it is away from the oceans.
SPEAKER_4: You have to pump it in.
SPEAKER_4: There's no electricity.
SPEAKER_4: The pumps don't work, the generators don't work.
SPEAKER_4: And the crew there is being reduced from 800 people down to 50.
SPEAKER_4: You're talking about essentially a suicide squad that know that they could get a lethal dose.
SPEAKER_4: So there's not enough manpower to make sure that seawater is covering everything, even as the seawater boils off.
SPEAKER_4: But I tell you at a certain point, even they will leave.
SPEAKER_4: And at that point, we'll have to abandon ship.
SPEAKER_4: And when you abandon ship, you're gonna have three meltdowns right in a row.
SPEAKER_4: That's the nightmare scenario.
SPEAKER_4: And the spend fuel pond, which is adjacent to the three reactors, is open to the sky.
SPEAKER_4: There's no cover.
SPEAKER_4: There's no vessel.
SPEAKER_4: It's just an open swimming pool of hot rods containing more waste than in the core of a nuclear power plant.
SPEAKER_4: Hollywood likes to focus in on the core, the meltdown, but it is the lowly waste dump that could actually cause the most damage.
SPEAKER_4: And that's what is now separating President Obama from the Japanese prime minister.
SPEAKER_4: President Obama's people are saying, hey, you got no water on this spend fuel pond.
SPEAKER_4: It could explode.
SPEAKER_4: It's dangerous.
SPEAKER_4: And the Japanese government is saying, no, no, no, things are stable.
SPEAKER_4: Well, I think the meltdown that we are seeing is the meltdown of the credibility of the Japanese government.
SPEAKER_1: So what is the future of nuclear fission?
SPEAKER_4: Well, the future of nuclear fission is a Faustian bargain.
SPEAKER_4: Faust was the mythical figure who sold his soul to the devil for unlimited power.
SPEAKER_4: And nations like Japan that have no coal oil reserves are reaching for this Faustian bargain.
SPEAKER_4: The price you pay is you have a tremendous amount of fission products, which are quite hot.
SPEAKER_4: These fission products can be released in a nuclear accident, and as a consequence, you have to take care of your nuclear power plants very carefully if you undergo the Faustian bargain.
SPEAKER_4: But now in light of this Japanese accident, many nations, including Germany, are rethinking the Faustian bargain.
SPEAKER_4: Unlimited power, the only price is your soul.
SPEAKER_1: One of the problems Japan also faces is where it is located geographically on earth.
SPEAKER_1: It's part of the ring of fire.
SPEAKER_1: So if they're trying to make their own energy without the natural resources of coal and oil, and they do it by nuclear, then they've got a nuclear power plant on fault zones.
SPEAKER_4: That's right, 90% of all earthquakes on the earth are in the Pacific ring of fire.
SPEAKER_4: It's the same fault line that leveled San Francisco in 1906.
SPEAKER_4: My grandfather was in that earthquake.
SPEAKER_4: He was part of the cleanup operation.
SPEAKER_4: It leveled Tokyo in 1923.
SPEAKER_4: It's caused some of the greatest tragedies in human history, the Pacific ring of fire.
SPEAKER_1: So your family and ancestry has been in the United States for more than a century, then?
SPEAKER_4: That's right.
SPEAKER_4: About a hundred years my family's been here, but we have relatives in Japan.
SPEAKER_4: And one of the things that our relatives are debating right now is whether to evacuate.
SPEAKER_1: For good.
SPEAKER_4: Well, until they can bring the reactor under control and until they can make sure that there's no contamination.
SPEAKER_4: However, at Chernobyl, realize that some of the land will be a dead zone for maybe centuries to come, because you have to multiply the half-life by 10 before it becomes relatively safe.
SPEAKER_4: So Chernobyl released cesium and strontium, half-lives of around 30 years.
SPEAKER_4: So in 300 years, parts of Chernobyl area will be usable.
SPEAKER_1: So that's where the radiation level goes below what people have determined to be safe.
SPEAKER_4: That's right.
SPEAKER_4: In fact, you have a piece of Chernobyl in your body.
SPEAKER_4: I have a piece of Chernobyl in my body, of course, in a microscopic form, but it circled the earth and the radiation from Japan is not dangerous to the United States, but it is already in the United States.
SPEAKER_1: We've got to take a quick break, but more StarTalk when we return.
SPEAKER_1: StarTalk Radio, our special Violent Earth Edition, inspired by the tragic earthquake and tsunami in Japan.
SPEAKER_1: Japan, of course, is a leader in earthquake-resistant building.
SPEAKER_1: They're no stranger to earthquakes.
SPEAKER_1: They know they live in the ring of fire.
SPEAKER_1: The culture is industrially advanced.
SPEAKER_1: And I think it's worth commenting that surely many more people would have died from the earthquake and tsunami were it not for the earthquake proofing of the physical infrastructure of that region.
SPEAKER_1: Steve, Steve Soder joining me on StarTalk, yes.
SPEAKER_3: Not just the earthquake proofing of buildings, but also the training and the education of what to do when there's a tsunami warning.
SPEAKER_3: Most of the people who would otherwise have been drowned headed to high ground as soon as they heard the warning.
SPEAKER_1: And some of the high ground are just buildings that would survive the earthquake at first and this rushing water in its lower levels afterwards.
SPEAKER_3: Correct, but even just the foothills.
SPEAKER_3: And many more people would have died had this population not been educated.
SPEAKER_1: This is an 8.9 earthquake.
SPEAKER_1: Not long ago, there was an earthquake in Haiti and that was a 7.0-ish.
SPEAKER_1: And can you compare these energies?
SPEAKER_3: Well, the energies, by two orders of magnitude in the earthquake, magnitudes actually translates to a thousand-fold increase in energy of the Japanese earthquake compared to the Haitian one.
SPEAKER_3: The difference was that...
SPEAKER_1: The difference in the death toll, because in Japan, the death toll will likely settle out around 15,000, between 10,000 and 20,000.
SPEAKER_3: Probably something like that.
SPEAKER_1: That's correct.
SPEAKER_1: Whereas in Haiti, it was a quarter million people.
SPEAKER_3: That's correct.
SPEAKER_3: There was, first of all, the earthquake, even though it was a weaker earthquake, was almost right under the capital city.
SPEAKER_3: Second, there was essentially zero earthquake preparation or education or construction to withstand earthquakes.
SPEAKER_1: And not only that, you go back to 2004, you get to the Indonesian tsunami.
SPEAKER_1: Jim, there was an offshore earthquake.
SPEAKER_1: What was the magnitude of that one?
SPEAKER_1: Do you remember?
SPEAKER_2: That was in the nines.
SPEAKER_1: Yes, in the nines.
SPEAKER_1: So that was huge, unfortunately.
SPEAKER_1: And so that was a tsunami that just rolled through, it was another quarter million people down.
SPEAKER_1: And so we look around the world.
SPEAKER_1: So it's remarkable that the numbers could be as low as they are in Japan.
SPEAKER_1: And so now we have a tsunami.
SPEAKER_1: And Steve, you've studied tsunamis and the history of human culture.
SPEAKER_1: In particular, there's an ancient Greek city, Helikia, that you studied.
SPEAKER_1: And you judge the end of that city to have been from a tsunami?
SPEAKER_3: Yes, well, according to the ancient writers who described the demise of the city of Helikia, which was on the Gulf of Corinth in Greece, it was destroyed by an earthquake and a tsunami.
SPEAKER_3: And then it submerged.
SPEAKER_3: And that's one of the earliest descriptions of a tsunami that we have.
SPEAKER_3: But the city seems to have been wiped off the face of the earth.
SPEAKER_1: So unlike Lisbon in 1755, which was destroyed by earthquake, fire and tsunami, that city was rebuilt.
SPEAKER_3: Yes.
SPEAKER_1: Helikia, after all was said and done, was underwater, is what you're saying.
SPEAKER_1: Permanently underwater.
SPEAKER_1: So big was the shift in the plates of the earth.
SPEAKER_3: Well, it was probably not the plates so much as local subsidence of the sediment.
SPEAKER_1: Land sinking.
SPEAKER_3: It was soft materials, unstable.
SPEAKER_1: Unstable.
SPEAKER_1: And so, how does an earthquake make a tsunami?
SPEAKER_1: Is it just the obvious it shakes the water?
SPEAKER_3: Well, the main thing is there's a change in level where the earthquake happens on the sea floor.
SPEAKER_3: And so the water is either displaced or fills in to make up for that.
SPEAKER_3: And then because water is fluid, it will be unstable and will form a wave.
SPEAKER_1: A wave of energy to move vast distances.
SPEAKER_3: Yes.
SPEAKER_3: And another way it can happen is sometimes an earthquake will trigger an underwater landslide and that will displace a lot of water.
SPEAKER_1: All you gotta do is displace water and you're done.
SPEAKER_3: And that would make a larger tsunami than the earthquake alone.
SPEAKER_1: So, from Brian Okoa, did I get the pronunciation of his name right?
SPEAKER_1: From our Facebook page, Facebook is StarTalk Radio, the finest StarTalk Radio.
SPEAKER_1: And we're also, our website is startalkradio.net.
SPEAKER_1: He asked, what kind of advances have been made in predicting and detecting tsunamis?
SPEAKER_1: Jim, NOAA, the National Oceanographic and Atmospheric Administration, don't they have buoys across the ocean?
SPEAKER_2: Yeah, especially in the Pacific Ocean, given the fact that it's making up the core of the Ring of Fire, and especially after the Indonesian earthquake in 2004.
SPEAKER_2: There are buoys that can actually measure wave height changes, and this information is transmitted to satellites, and therefore transmitted to tsunami warning centers.
SPEAKER_1: I've seen the Pacific Ocean.
SPEAKER_1: The waves are jumping up and down all the time.
SPEAKER_1: So how is it going to know whether it's a tsunami wave versus just some turbulence in a local storm?
SPEAKER_3: Well, I think that there are patterns, and in the wavelength and the timing, there's a regularity, you can sort that out.
SPEAKER_1: Okay, so you need, obviously, more than one buoy to do this.
SPEAKER_1: Yes.
SPEAKER_1: You need a network.
SPEAKER_1: A network of buoys, so that's the catch here.
SPEAKER_1: And so when you have a network, you can actually measure things like the speed of the tsunami moving across.
SPEAKER_3: The height of the wave.
SPEAKER_1: And the height of the wave.
SPEAKER_1: So in mid-ocean, how high is a tsunami wave?
SPEAKER_3: Well, it's actually not very high, maybe a foot or something like that.
SPEAKER_1: Just a foot, so if you're a ship at sea, when a tsunami rolls under you, you wouldn't even know.
SPEAKER_3: You would hardly know it because the wavelength is enormous.
SPEAKER_1: Wavelength is the distance from peak to peak of this wave.
SPEAKER_3: Right, that could be like hundreds of miles, and it's passing, it might take an hour to pass.
SPEAKER_3: Well, there'd be a slow rise and fall of your boat.
SPEAKER_3: You wouldn't even know it.
SPEAKER_1: You wouldn't even know it.
SPEAKER_3: But as that wave goes into the shallow areas, it slows down.
SPEAKER_1: As it comes near the continental shelf, and so you have to come to the shoreline where you're sea level.
SPEAKER_3: Right, and as it's slowing down, as it's getting shallower at the leading edge of the wave, the water coming behind it is moving faster, so it piles up and it rises.
SPEAKER_1: And it rises, and it reaches a point where it just overtakes the shoreline and just keeps moving in.
SPEAKER_3: Yes.
SPEAKER_1: Because that energy is, so people think of a tsunami in mid-ocean as moving water in mid-ocean, but it's not really that.
SPEAKER_3: It's moving energy.
SPEAKER_1: It's energy manifested by this bump that transfers from one location to the other completely across the Pacific.
SPEAKER_1: How fast does the wave move?
SPEAKER_3: I think it can be hundreds of miles an hour.
SPEAKER_3: Depends on the depth.
SPEAKER_1: Okay, so in this case, if I remember correctly, it was 500 miles an hour.
SPEAKER_1: It's fast as a jetliner.
SPEAKER_1: Because I was looking at the times where they predicted when it would hit the west coast of the United States.
SPEAKER_1: And I said, that's about how long it takes to fly.
SPEAKER_1: Steve, we were discussing earlier offline that the Pacific Northwest is at risk to tsunamis.
SPEAKER_3: Well, there is a subduction zone, a place where the Pacific plate is actually diving under North America, along the coast of Northern California, Oregon, Washington, British Columbia.
SPEAKER_3: That is capable of making large earthquakes and there's geological and actually historical evidence that there have been massive earthquakes there with a repeat time on the order of something like 350 years.
SPEAKER_3: The last one was in the year 1700.
SPEAKER_2: Now, this evidence is debris deposits, is that right?
SPEAKER_3: Yes, there's debris deposits, there's sunken forest.
SPEAKER_1: So debris from a tsunami that came far into land, is this?
SPEAKER_2: We've just seen images, unfortunately, of the debris off the coast of Japan.
SPEAKER_2: So this is natural debris, is that right?
SPEAKER_3: Yes, but there was also subsidence and so there's a drowned forest, for example.
SPEAKER_1: A drowned forest.
SPEAKER_3: Yes, where the trees were all killed and from the tree rings, you can date that event exactly to the year and it corresponds to a tsunami that was recorded across the Pacific in Japan in the year 1700.
SPEAKER_3: So the source of that tsunami was along the coast of Northwest United States.
SPEAKER_1: And that was a tsunami headed back the other way.
SPEAKER_3: Exactly.
SPEAKER_1: Back west.
SPEAKER_3: Yes.
SPEAKER_1: Steve Soder, Jim Webster, thanks for coming on the show.
SPEAKER_1: You've been listening to StarTalk Radio and I've been Neil deGrasse Tyson.
SPEAKER_1: As always, keep working up.