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Earthquake triggering, and why we don’t know where the next big one will strike


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As I came through airport security in Connecticut, upon presentation of my California driver’s license, the TSA officer asked me, "Aren’t you folks worried about how that big Japan quake is going to hit you next?" I was glad to be able to tell him that we’re not any more worried than we were before, and that a writer had just made that up. I didn’t ask him where he got that idea, but on my mind already was Simon Winchester’s column in Newsweek magazine on March 13. The article was wrong, and that fact has gotten a lot of traction in the blogosphere—and in real newspapers, if a distinction still exists.

The Newsweek article argues that the relatively small but very damaging Christchurch, New Zealand earthquake of February 22, 2011, the very large Chilean earthquake of Feburary 27, 2010 and the recent great earthquake in Japan constitute "triggering events" around the Pacific Plate, stating, "That leaves just one corner unaffected—the northeast. And the fault line in the northeast of the Pacific Plate is the San Andreas Fault, underpinning the city of San Francisco." After this geographical error, Mr. Winchester states that the stresses around the San Andreas have built to "barely tolerable levels" and that a triggering event is required to set off a great quake.

Mr. Winchester, a well-known author of several popular science books on geological topics, is much better versed in the history of geological events, and much of the science around them, than most people. However, his piece in Newsweek contains wrong information, baseless predictions and an ominous tone that is more fear-mongering than warning. We had a bit of correspondence about my objections, which wonks can read on my Facebook page. In that correspondence and a follow-up column in the Daily Beast, Mr. Winchester defends his earthquake prediction and implies that earthquake scientists are either hiding something or just plain stupid for not sharing his views.

I’m not saying Mr. Winchester is wrong about the great risk to San Francisco from the San Andreas Fault, on the contrary; I fully agree. And I appreciate the intention to grab the moment after the tragedy in Japan to point out the risks while public and media are showing so much interest in earthquakes. However, some of Mr. Winchester’s "facts" are wrong, and logic is deeply flawed. I’m grateful for this chance to set the record straight, even though far fewer people will read this posting than the Newsweek column, which has already done its damage and faded into the fog of yesterday’s Internet.

These are the points I’d like to make to the author and publishers of that piece:

  • Just because something appears to make sense, that does not mean it is true. Often times, more than one story appears to make sense, given the available information.
  • Just because you have not read about an idea already, that does not mean you are the first to have that idea, especially if you don’t read much.
  • Natural systems are incredibly complex, and the fact that we have not yet understood and predicted every detail does not mean the scientific community is negligent or hiding something.

Do earthquakes trigger other earthquakes?

The risk of a big earthquake occurring close to a large shock, and soon after it, is well established1,2. Locally, an earthquake changes the stress on surrounding faults, shakes them up and causes aftershocks. As the seismic waves travel across the planet, they have subtle effects on faults near and far—which can directly trigger more earthquakes, close in time but not in space to the original earthquake.

For example, direct triggering was documented during a 2002 earthquake in Alaska3. A few minutes after the quake, when the seismic waves reached Yellowstone, a flurry of small earthquakes occurred there. We can say with some certainty that the Denali quake triggered the Yellowstone quakes because we understand the timing as well as the mechanism of energy transfer. So geophysicists might not be able to predict the exact location and timing of each individual small quake in Yellowstone, but we can say with confidence that the probability of those Yellowstone quakes increased when the seismic waves from Alaska arrived in Yellowstone. We can predict that future large earthquakes around the globe are also likely to increase the probability of quakes in Yellowstone4.

Does that mean that the Japanese earthquake caused increased risk on the San Andreas Fault, or any other?

We don’t know. And here’s why. There are two ways to approach this question:

1. If we know the direct causes of earthquakes, we can determine whether those causual factors have increased.

2. Even without knowing the causes, we can look at the numbers and see whether big quakes are more likely to follow big quakes, globally.

Unfortunately, we don’t usually know what caused an individual quake to occur at the exact moment in the exact location when it occurred. In the direct-triggering scenario above, we can say that the frequency of earthquakes increased immediately after the seismic waves arrived, and infer that the seismic waves caused the increase in small earthquakes.

But what if the increase in small earthquakes was sustained for a long time after the waves had passed? We observe that after a big earthquake, the planet may "ring like a bell"5 for hours or days, but the ringing of a bell doesn’t last indefinitely. So how can we look at the recent damaging earthquakes (for example, in Haiti, January 12, 2010; Chile, late February 2010; and New Zealand, February 20116) and say that they are causing each other? If it exists, this kind of subtle increase in risk is detectable with statistics, but to really distinguish between a random pattern of events and a pattern that indicates a common cause, we need numbers. Can you tell with one flip of a coin whether that coin is weighted? Can you tell with 10 flips? 100?

There have been 82 recorded earthquakes since 1900 which were Magnitude 8 or greater. Five of these were M9 or greater. These are the numbers; this is what we have to work with. We know that the frequency of these great quakes is relatively rare for any given tectonic boundary—every 800-1,100 years in the case of the Sendai area7, every ~600 years in the case of Cascadia (Oregon–Washington–British Columbia). Looking at the graph of these events, you might pick out an apparent spike in large earthquake activity around 1960 and another one at the present time.

I could look at the current high rates of large earthquakes and tell you that a big one is due somewhere next week, and you couldn’t prove me wrong. I could just as well look at the same data and tell you that the apparent cluster of earthquakes is over, and the rate of large earthquakes will drop back to lower rates similar to the 1970s, and likewise, you couldn’t disprove me. But you could point out that the non-uniqueness of my answer renders my predictions useless.

Every earthquake that occurs extends the record, giving us a better shot at figuring out the details of the pattern. If I tell you that my coin lands on heads 80 percent of the time, and therefore the next flip will be heads, you should call me out, because I cannot really know what the next flip will bring. For now, with earthquake prediction, we still have not seen enough flips of the coin.

Mr. Winchester argued in the Daily Beast column that the earthquake on one edge of the Pacific Plate would "…more probably trigger an event on the same tectonic plate family…". Possible? Yes. But one could just as well argue that the westward motion of the Pacific Plate during the Sendai earthquake would effectively relieve stress on the San Andreas at its eastern edge, thereby making an earthquake there less likely than before. Again, both ideas may appear to make logical sense—but this does not make either or both any more correct. Logical exercises like this are a good place to start the process of hypothesis forming, followed by independent testing, which is at the core of scientific practice.

Why the scientists are not not telling you what you want to know

Contrary to Mr. Winchester’s suggestions, we (scientists) really want you (the public) to know what we are doing! We want you to care about where your tax dollars are going (a very, very small portion of your tax dollars, anyway), and we desperately want you to use our discoveries to build a safer, cleaner, more sustainable and stable society. But we tend to scuttle like cockroaches from the media spotlight, for this reason:

If we are wrong, or misunderstood, the consequences can be dangerous for the public and brutal for our careers. Therefore, we tend to keep things under wraps, waiting until we are very sure, and results are vetted in numerous fora, before we communicate with the public. Even then, we are careful of members of the media, who often have different priorities than we do. This reduces the risk, but sometimes also the likelihood of publicizing the new knowledge we discover. This does not mean that we knowingly withhold information that could affect public safety!

To save lives and property, we need to be able to predict locations and times of individual earthquakes within hours or days. We currently cannot do that. To mitigate the overall risk, we need to be able to predict regions where earthquakes are likely to occur, offer a general timescale and give an idea of how large they might be. This we do very well, most of the time, although the short available record in many places means we are still tragically surprised by low-frequency events like the Sendai earthquake.

Popular writers have less apparent authority than professional scientists with Ph.D.s. This does not necessarily mean that they are less knowledgeable, and I know of many who maintain cutting-edge familiarity with the fields about which they write. However, it does mean they are not under the same obligation to be right, and they are not necessarily committed to careful fact checking. I am taking Mr. Winchester’s point to heart when he lashes out at the non-communication from the science community—not, however, his assertion that our relative silence gives him permission to fill the gap with whatever he likes.

So I’ve made a commitment to jump into the fray more frequently, to not just make scientific information available but actively offer and promote it in public settings like schools, museums and the popular press, and to publicly challenge misinformation when I see it.

Chuck Ammon, Nicholas van der Elst, and Alex Hutko provided information or assistance for this column, but any errors are all mine. C.R.

Figure courtesy of Chuck Ammon, after Ammon et al. (2010) Great earthquakes and global seismic networks, Seismological Research Letters v. 81 n. 6 pp. 965-971.

Notes:

1 Husen et al. (2003) Changes in geyser eruption behavior and remotely triggered seismicity in Yellowstone National Park produced by 2002 M 7.9 Denali fault earthquake, Alaska, Geological Society of America Bulletin v. 32, n. 6 p. 537-540.

2 van der Elst and Brodsky (2010) Connecting near-field and far-field earthquake triggering to dynamic strain, Journal of Geophysical Research v. 115 B07311

3 Parsons and Velasco (2011) Absence of remotely triggered large earthquakes beyond the mainshock region, Nature Geoscience v. 4 n. 4 p. 1-5

4 The susceptibility of the Yellowstone area to triggered earthquakes is attributed by Husen et al. (2003) to the overpressured geothermal system at depth.

5 Stein and Okal (2005) The 2004 Sumatra earthquake and Indian Ocean tsunami: What happened and why?, Visual Geosciences v. 10, n. 1 p. 21-25.

6 The degree of damage and injury caused by an earthquake depends not only on magnitude but a host of other factors including human population and construction. Of these earthquakes, suggested by Winchester to be key "triggering events", Christchurch and Haiti are were small to appear on the plot (M6.3 and M7.1, respectively) See the complete list at the USGS site to compare magnitude and total fatality.

7 Minoura et al. (2001) The 869 Jogan tsunami deposit and recurrence interval of large-scale tsunami on the Pacific coast of northeast Japan, Journal of Natural Disaster Science, v. 23 n. 2 p. 83-88.

8 Goldfinger et al. (2003) Holocene earthquake records from the Cascadia subduction zone and northern San Andreas Fault based on precise dating of offshore turbidites, Annual Review of Earth and Planetary Sciences v. 31, n. 1 p. 555-577.

9 Modified from Ammon et al. (2010) Great earthquakes and global seismic networks, Seismological Research Letters v. 81 n. 6 p. 965-971.

About the author: Dr. Christie Rowe is a researcher in Earth & Planetary Sciences at the University of California, Santa Cruz. She is part of a team of geologists, seismologists, geophysicists and experimentalists in rock mechanics who are striving toward an integrated model of how earthquakes work. Love and hate mail should go to christierowe[at]gmail.com. Photo: Pete Lippert

The views expressed are those of the author and are not necessarily those of Scientific American.






Comments 23 Comments

Add Comment
  1. 1. ruspert 12:59 pm 03/30/2011

    Perhaps, and then again, maybe not, lets wait and see and then if nothing happens,then, probably not, but if it does, again, maybe.:)

    Link to this
  2. 2. joseph2237 1:19 pm 03/30/2011

    First thing that comes to mind is "how do you know he is wrong" since you don’t have a "plan" or a predictor yourself, your not qualified to refute any claim.

    All funds given to the USGS is a waste of money. The last forty years of poking, sampling, snifing, and temperature and pressure taking hasn’t produced one shred of predictablity. We pay these people to travel the world to take temperatures and sample the air. For what? The only good thing we have has come from Oceanographers. We have a Pacific tsunami early warning system. What have geologists done for us. They can tell us without a doubt that the Bible is full of it and the Earth is 4 billion years old. That is what we get for forty years of global throtting and millions of dollars.

    I can live with knowing that the Earth is much older than the Bible says, but when Geologist the world over have collectively decided that the challenge of earth quake prediction isn’t worth the effort tells me they are more interested in maintenaining the status quo of global throtting and job security.

    Link to this
  3. 3. gehn 2:30 pm 03/30/2011

    Uggg,

    Great article Dr. Rowe. It is unfortunate that some people may never understand this.

    Link to this
  4. 4. shortstack81 3:13 pm 03/30/2011

    USGS’s goal never was to predict earthquakes. And what is "global throtting?"
    Dr. Rowe knows he’s wrong because she just sited several studies that state so.

    Link to this
  5. 5. kwinkunks 3:22 pm 03/30/2011

    Good grief, that register-to-comment process is awful. IMO you’d have way more comments if you moved to something friendlier.

    But I have just about got the spirit left to say: nice post, and thank you. After quite a bit of rhetoric and unwarranted definitiveness on this subject recently, it’s great to see a seismologist give such an honest, rounded account of the science and speculation.

    Geoscience is important: there’s so much we don’t know about the earth.

    Link to this
  6. 6. drrocks1982 3:43 pm 03/30/2011

    Imagine what you could buy with the $3 of yearly savings in a USGS-less world. You realize they do a lot more than not predict earthquakes, right?

    Link to this
  7. 7. HowardB 4:27 pm 03/30/2011

    That pretty much says it.
    If there is anything we should glean from Ms Rowe’s pretty good article, it is that the amount we know about earthquakes is TINY. The amount we don’t know is ENORMOUS.
    She is absolutely write to take Mr Winchester to task. His writing was full of worthless speculation and baseless assertion. I personally suspect his writing is motivated by political views more than anything else. And what I mean by that is, that it seems he has the view that waking people up about the dangers of catastrophic quakes is such a worthwhile thing that it excuses the ‘stretching’ of the truth.
    This is not science. If he feels that way he should just come out and say it. That would be fair comment. But disguising it as science is disingenuous.

    Link to this
  8. 8. drrocks1982 6:01 pm 03/30/2011

    Add this to the list of possible motivations: http://www.amazon.com/Cascadias-Fault-Earthquake-Tsunami-Devastate/dp/1582436436/ref=sr_1_26?ie=UTF8&qid=1301522485&sr=8-26

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  9. 9. Carlyle 7:23 pm 03/30/2011

    The chief of the IPCC, Dr Rajendra K Pachauri says human activity is raising the frequency of tsunamis (Therefore earthquakes).
    No other member of the IPCC has disputed this claim. Who still believes these imposters?
    SEE: http://articles.timesofindia.indiatimes.com/2011-03-14/coimbatore/28687815_1_harmony-green-drive-renewable-energy-sources

    Link to this
  10. 10. Martin Wirth 7:50 pm 03/30/2011

    Years ago, I solved a problem in fluid dynamics to improve the predictability of plastic flowing through dies and molds. We needed a computer model to make my solution useful. That was one semi-fluid material with a single set of properties that varied with pressure, temperature, and the rate of shear.

    Within a mile of my home there are a lot of different minerals including gneiss, schist, quartz, orthoclase, feldspar, and a variety of feldspathic granites with varying granularity and composition. All of these minerals will each have their own set of unique properties that vary with pressure, temperature, and rate of shear. While hiking, I’ve considered the prospect of dynamically modeling such a complex system of materials and the challenge is staggering to contemplate for even one cubic mile of this stuff.

    The Earth is about 7926-miles in diameter consisting of a vast complex of materials and hidden formations that, while not impossible to model, are largely unknown because of our inability to collect adequate samples of what lies even a mile under our feet. The crust floats atop a fluid mantel that surrounds an iron core. This is an excellent but low-resolution approximation that is not capable of predicting earthquakes. Earthquake prediction would require a much more detailed, higher-resolution model.

    A well known habit of the human mind is the tendency to substitute fantasy for the unknown. There’s nothing wrong with this provided we accept that fantasy is imaginary and never conflate it with the facts. I think this is why so many readers and pundits get a little bit upset with experts like Dr. Christie Rowe. Breaking pretty balloons and hauling the unwilling back to reality has never been a popular sport.

    Link to this
  11. 11. drrocks1982 4:20 am 03/31/2011

    "The crust floats atop a fluid mantel that surrounds an iron core."

    This is a common misconception, but the mantle is at no point fluid. Shallow portions of it immediately beneath the crust may contain small amounts of melt, but shear waves can propagate through the mantle hence it is not fluid.

    Link to this
  12. 12. PeteInRedondo 4:28 pm 03/31/2011

    Professor Rowe – First, a big thanks for taking the time to write this article.

    Let me be constructive and suggest two things …

    1) Can you make the data set (shown in your figure) available on your university Web site? It looks like a nice set of data for larger quakes over the past 100 years – so would you consider sharing it?

    2) If I take a cursory look at your data – which is relaly a collection of rare events – there are two possible interpretations. One possibility is that the clumps of data for very large quakes are indeed random groupings. This is certainly quite plausible. But to check this, why not go back and carefully compare the locations of all these large quakes (in the clumps) against known tectonic boundaries? If indeed the outcomes are random, you might expect that the locations of the events would fall randomly around the globe. It seems to be worth checking.

    Alternatively, if the quakes in the clumps tend to be found around the boundaries of certain specific tectonic plates – would that not suggest the possibility that sometimes these plates undergo larger-scale movements (or re-alignments)? This idea also seems plausible. After all, how exactly can a series of jagged, interlocking pieces of the Earth’s crust continue to gradually change their positions over time, without sometimes making bigger shifts in alignment? Furthermore, if as an example the Pacific Plate is currently undergoing a larger re-alignment, it would seem likely that neighboring plates (Nazca, Australian, Philippine, Juan de Fuca) might also generate occasional large ruptures. Hence, data on neighboring plates should not be dismissed as "false" when checking the re-alignment hypothesis for the Pacific Plate.

    These are just thoughts.

    Finally, I am surprised by the criticisms of some readers towards the USGS. I have visited their Web site recently and thought it was very informative – really quite well done! In addition, if you take a look at work they have funded over the last few decades, it’s very clear that they have "turned over every possible stone" in an effort to find earthquake precursors … magnetometers, electrical conductivity, acoustic emissions, all kinds of seismology, animal behavior, … you name it. Based on the efforts funded, it seems to me that earth scientists care a great deal about trying to find adequate ways to predict earthquakes. It’s just a tough problem, that’s all.

    Best wishes on your research!

    Pete in Redondo Beach

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  13. 13. christierowe 8:26 pm 03/31/2011

    Hi Pete, thanks for your comments. The data in the figure is from a 2010 paper by Chuck Ammon (cited in the caption) and he generously provided an updated figure for this post which includes the most recent events.

    I don’t know of any evidence that suggests the Pacific Plate is changing velocity at the current time, although there is evidence of big changes in the past. An important thing to consider when thinking about stress transfer across plate boundaries is that plates are not perfectly rigid – there are cracks and faults and fracture zones and a substantial capacity for viscous behavior.

    I would not expect earthquakes to be randomly dispersed in space, because the relative velocities along plate boundaries are not randomly dispersed in space. In addition, different plate boundaries have different behaviors with respect to how they take up that motion – some areas creep and others are in a cycle of locked periods punctuated by earthquakes. A major focus of my research the rock properties of faults, and trying to understand why faults sometimes lock and sometimes creep. I am making slow progress.

    I share your sentiments about the (in my view) arbitrary criticism of the USGS. Would one also suggest that because we have not yet cured all cancers, that we should just give up and de-fund all cancer research? Paying for research is not a purchase of a finished project, it’s an investment in the future that we may have more knowledge and more technology when we get there.

    Thanks for reading – Christie Rowe

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  14. 14. ennui 8:47 pm 03/31/2011

    Who is that "WE" in that We cannot predict earthquakes by several hours or more?
    The technology is here to do it. "WE" does not know about the technology.
    The reverse system to stop a tornado is used. Of course the followers of WE ware not interested in that either.

    Link to this
  15. 15. Martin Wirth 10:56 pm 03/31/2011

    Most of the science describes the layers of the mantel in plastic flow(1). So, I call it a fluid in the sense that glass is a fluid albeit one with such high viscosity that it seems to be a solid. It flows at a rate of a few cubic millimeters per liter per century. You can see the effect in very old window panes that have horizontal waves in them. This is caused by the weight of the glass slowly flowing down on itself.

    Water is a liquid because molecules diffuse rapidly. Anything that flows is a fluid even if no diffusion occurs. The mantel flows(1) and is fluid but I would agree that calling it a liquid would not be precise.

    The mantel also has convection(2). Tectonic plates float around and grind against each other on the fluid mantel. Many fluids have high enough viscosity to easily transfer shear forces. Glasses are prime examples of this. Thixotropy is also a property of some fluids in plastic flow. Thixotropy is the reduction of viscosity as the rate of shear increases. Fresh mixed concrete maintains low viscosity so long as it undergoes shear flow. When it stops, its viscosity increases until it sets into a solid form. In the mantel, various minerals and compositions thereof are probably thixotropic, which would be supported by your observation that most of the fluidity (or lower viscosity behavior) has been measured at the upper mantel where slow convection currents rubbing against tectonic plate bottoms and slab subduction are agitating the material. Of course, friction also causes a terrific amount of heat and thermal expansion to force magma out of volcanoes.

    Oil is an example of a negatively thixotropic fluid. Increasing the shear rate makes the viscosity go up. This is what makes it nice for keeping the solid surfaces of metal separated in engines, gearboxes, and bearings.

    As I alluded in my first post, modeling fluids with a mix of solids having a variety of elasticities and varying viscocities is a complex problem. Then toss in thixotropy and variations across temperature and pressure to get a clearer idea of how I view modeling the Earth. Then try to ascertain the geometrical composition of your subject to a high resolution without any direct samples. Of course, there are scientists and programmers at work on this difficult problem.(3)

    Link to this
  16. 16. Martin Wirth 11:01 pm 03/31/2011

    Citations with more citations for my previous comment.

    1. en.wikipedia.org/wiki/Asthenosphere
    2. en.wikipedia.org/wiki/Mantle_convection
    3. en.wikipedia.org/wiki/Computational_Infrastructure_for_Geodynamics

    Just add the http:// thing in front of them.

    Link to this
  17. 17. Numerouno711 2:07 am 04/1/2011

    Dr. Christie Rowe,
    I also think that a lot of information is kept under folds by our political as well as scientific system and usually what the general public gets to hear is a very superficial version and that too either at the 11th hour or after a span of many many years.I am not a scientist but I believe that to know about science you don’t need to be a scientist.You need to be curious to know what all is around you.But the subject matter is not made available to the public.
    But your argument is also right, until the piece of information or discovery is not substantiated with the proper data , it holds no water like you said "results should be vetted in numerous fora".

    It took Albert Einstein 10 years to prove his general theory of relativity as he had to wait for The solar eclipse.

    Link to this
  18. 18. Numerouno711 2:10 am 04/1/2011

    Dr. Christie Rowe,
    I also think that a lot of information is kept under folds by our political as well as scientific system and usually what the general public gets to hear is a very superficial version and that too either at the 11th hour or after a span of many many years.I am not a scientist but I believe that to know about science you don’t need to be a scientist.You need to be curious to know what all is around you.But the subject matter is not made available to the public.
    But your argument is also right, until the piece of information or discovery is not substantiated with the proper data , it holds no water like you said "results should be vetted in numerous fora".

    It took Albert Einstein 10 years to prove his general theory of relativity as he had to wait for The solar eclipse.

    Link to this
  19. 19. Numerouno711 2:14 am 04/1/2011

    Dr. Christie Rowe,
    I also think that a lot of information is kept under folds by our political as well as scientific system and usually what the general public gets to hear is a very superficial version and that too either at the 11th hour or after a span of many many years.I am not a scientist but I believe that to know about science you don’t need to be a scientist.You need to be curious to know what all is around you.But the subject matter is not made available to the public.
    But your argument is also right, until the piece of information or discovery is not substantiated with the proper data , it holds no water like you said "results should be vetted in numerous fora".

    It took Albert Einstein 10 years to prove his general theory of relativity as he had to wait for The solar eclipse.

    Link to this
  20. 20. Numerouno711 2:15 am 04/1/2011

    Dr. Christie Rowe,
    I also think that a lot of information is kept under folds by our political as well as scientific system and usually what the general public gets to hear is a very superficial version and that too either at the 11th hour or after a span of many many years.I am not a scientist but I believe that to know about science you don’t need to be a scientist.You need to be curious to know what all is around you.But the subject matter is not made available to the public.
    But your argument is also right, until the piece of information or discovery is not substantiated with the proper data , it holds no water like you said "results should be vetted in numerous fora".

    It took Albert Einstein 10 years to prove his general theory of relativity as he had to wait for The solar eclipse.

    Link to this
  21. 21. kwinkunks 7:50 am 04/1/2011

    @Martin: The notion that glass flows is very widespread. It doesn’t, at least not at ordinary room temperature (or anything close). Google ‘glass flow myth’ or similar.

    You also mentioned oil being anti-thixotropic (‘rheopectic’). It isn’t. While some synthetic or modified lubricants are, light mineral oil is very close to being a Newtonian fluid.

    Link to this
  22. 22. PeteInRedondo 1:09 pm 04/1/2011

    To Reader Ennui and Others:

    An early warning system for earthquakes does exist in principle, and it operates in Japan. However, you should understand that we’re not talking about warnings of hours or minutes … warning times are measured in seconds (see my comments below).

    So far an earthquake warning system has not been implemented in the USA. There are knowledgeable people, including earth scientists, who are trying to get this system working in California. The effort in is spearheaded by Prof. Allen at the Seismology Labs at U. C. Berkeley. The main delays seem to be related to (1) Bringing the warning system to a level of technology where it can be effective and reliable, (2) Obtaining the necessary funding at the State and Federal level. Researchers are actively working on both issues, but it is unclear when this system will get over the hurdles to put it into action.

    The earthquake warning system is not capable of giving warnings for all kinds of earthquakes. For example, if you live near the epicenter of a quake, you will get no warning. By the time the earthquake waves arrive, it’s essentially too late. That’s because the warning system is based on detecting earthquake waves that happen at the epicenter of an earthquake, and then electronically triggering alarms (sirens) at greater distances. So the warning system can only work for people who are living many miles away from the epicenter of the quake. Nevertheless, this still provides a really valuable warning and could save many lives. Let me give you an example. Since I live in Redondo Beach, on the coast of the city of Los Angeles, the warning system could (in principle) give me a 20-30 secs warning if there is a significant earthquake on the southern San Andreas. That’s not bad … it’s enough time to take immediate action and find some safe cover from falling debris.

    I have no connection with the USGS, or with any of the earth scientists involved. I am just one of millions of people who are residents of Los Angeles. Our date with destiny is coming – in fact it is already long overdue. Just like the people of Sendai, Japan … we will have to cope with high levels of destruction when the Big One hits our city. I have spoken to the USGS and earth scientists, and that’s how I am able to relay the information in this message. But I have also spoken to ordinary people in the city where I live – and I must say that we are far less prepared for a major disaster than the Japanese people were (before the recent 9.0 quake).

    Pete in Redondo

    Link to this
  23. 23. sasquake 7:06 pm 06/11/2011

    A historical eq in 869 destroyed a castle town & was confirmed by geologic studies,showing tsunami runup on Sendai Plain 4 km inland; but Minoura’s 01 warning in J. Nat. Dis. Sci.(the possibility of a large tsunami striking the Sendai Plain is high) was not heeded (sometimes not even believed). Nor was a 05 talk by Y. Ito?, that all of the M 7-8 historic subduct. zone eqs along the coast of NE Japan had been too small to relieve all the plate strain accumulated from plate convergence of 83 mm/yr; forecasting that strain was likely only to be relieved in one Giant Quake.
    The debate is not about how quickly scientific findings should influence disaster-mitigation policies; or about eq triggering. The debate should be whether Probabilistic Seismic Hazard Assessment should continue to be imposed and blindly followed, despite its dramatic ongoing failures in protecting public safety and economic resiliency (> 708,000 deaths in last decade). PSHA emphasized preparation for a “likely” smaller eq, while ignoring consequences from the maximum potential earthquake/tsunami(MCE).
    “Sometimes attaining the deepest familiarity with a question is our best substitute for actually having the answer.” Deterministic Seismic Hazard Assessment (DSHA) would have prevented disregard of the 869 Jogan event: MCE would = M 9+, tsunami inund. = 10-20 m wave ht., coseismic subsidence at coastline = 1-2 m. The 1½ yr. delay (after prominent seismologist Y. Okamura “warned of a debilitating tsunami” at a `09 working group reviewing the seismic safeguards for the Fukushima plant)-meant reconsideration of the 869 disaster was “in the midst of analysis when this earthquake hit.”-despite many warnings (direct and indirect) 2001-2010.
    In PSHA, the perceived likelihood of an event strongly influences the end result: whether it is actually considered in design. DSHA quickly (in days or weeks) can provide reality check, based on MCE, for effective public safety, disaster mitigation, and economic resiliency.
    True scientific consensus (what everyone agrees) was overridden by “majority rule” of a technological elite working group during seismic hazard review of the Tohoku Daiichi nuclear plant, which included only 2 tsunami experts. Not needed is more research, analysis, or risk assessment. Needed is for earth scientists – seismologists-engineers to convey effectively their conclusions (based on their special knowledge, experience and judgment) to better protect society.
    “Look how often the unexpected happens, and yet we still never expect it.”

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