Climate change and earthquakes: It's complicated

By Maggie Koerth-Baker

In the wake of the Tohoku earthquake and tsunami last March, I started seeing a lot of headlines like this:

"Does climate change mean more tsunamis?"

"Did climate change cause the Japanese earthquake?"

In those stories, environmentalists and climate science deniers went head-to-head, with one side pointing out yet another unintended consequence of fossil fuel consumption, and the other side pointing and laughing at what it saw as patently ridiculous fear-mongering. Missing: The nuance. And you know how much I love the nuance.

This is a story that contains a whole lot of yesbut. Yes, it really does make sense that climate change could trigger earthquakes. But it's very, very unlikely that that effect is responsible for any of the monster quakes we've experienced recently. And behind that apparent contradiction lies some really, really interesting science.

Let's start with a quick overview of why scientists think climate change and earthquakes are connected.

On the surface, this does sound pretty insane. Climate change is about the greenhouse effect increasing the global average temperature. The impacts of climate change tend to be things that are linked, somehow, to weather and climate—droughts, storms, changing habitats, melting ice caps. Earthquakes, on the other hand, are about landmasses bumping up against one another. That's plate tectonics, not El Nino. But the basic theory actually does make a lot of sense. And it's really just a logical extrapolation of some well-established natural phenomena.

It begins with the forces that cause earthquakes. The surface of this planet, what we see, is actually the crust—just the crispy coating on a ball of nougat. The crust is broken up into large pieces and those pieces move over the surface of the gooey mass beneath. At the borders, the pieces of the crust are riddled with faults. These are places where the crust has broken and different pieces are moving in different directions—away from each other, towards each other, or slipping past one another.

These faults can get stuck on one another and, over time, build up tension like a rubber band being pulled back. Earthquakes happen when the tension gets released and the pieces of the fault move suddenly with the pent-up force of many decades.

The Earth naturally forms these tense spots. That's just how the movement of the crust works. But things that happen on the surface of the crust can affect when and where the tension gets released.

Under Pressure

The crust of the Earth seems like a big, mighty, un-moveable thing when you're walking around on it, but it's actually relatively sensitive. Over decades, scientists have amassed evidence that the application of a heavy weight to the surface of the crust (or the removal of that weight) can trigger earthquakes.

For instance, when we build major reservoirs, we look for places that don't have a lot of seismic activity. For obvious reasons. But, sometimes, after the dam has been built and the reservoir has filled, the area will start to become seismically active. The big-name example here is the earthquake at Koyna Dam in India's Maharashtra state. The reservoir was filled in 1963. People began reporting small shakes soon afterwards and, in 1967, a magnitude 6.3 quake struck the region. The epicenter was very near the new reservoir. "There's a really compelling association with a reservoir here," says Susan Hough, a seismologist with the United States Geological Survey. "In this case, it was a part of India that was not all that active until the reservoir was built."

These time/place associations between earthquakes and reservoir building have happened reliably enough that scientists are confident that there is a connection. This isn't a controversial theory.

Nor is it controversial that the buildup and melting ice and snow can trigger earthquakes. The evidence for this comes from echoes of Earth's last Ice Age, when glaciers (heavy glaciers) stretched all the way down from the North Pole into places that are now quite decidedly temperate. When the Ice Age ended, the glaciers slunk back to to the Pole. And there's good evidence of a major increase in seismic activity that corresponded to the time and place where those glaciers were receding.

"The evidence includes a big increase in earthquake and volcanic activity in previously glaciated areas, such as Scandinavia and Iceland, increased volcanic activity in oceanic areas, and a greater prevalence of large submarine landslides," says Bill McGuire, professor of geophysical & climate hazards at University College London. "Some of [the landslides], the Storegga Slide off Norway 8,200 years ago, for instance, triggered major tsunamis that left their mark in the UK and elsewhere in the North Atlantic."

The effects aren't limited to things that happened thousands of years ago. Hudson Bay in Canada is basically just a divet where a patch of crust sunk under the weight of a glacier. It's slowly rebounding, in a way that we can measure today. In fact, in another 10,000 years, Hudson Bay won't exist at all, says Henry Pollack, professor of geophysics at the University of Michigan. Meanwhile, small earthquakes that happen today in Eastern Canada are thought to be associated with the Bay's slow spring-back.

All of this works because the movement of the crust can be influenced by the weight sitting on top of it. If you place a heavy weight, like a reservoir or a glacier, on top of a fault line, it might not move the way it otherwise would. Remove the weight, and it might go back to its original routine, or move in a different way. Either action, adding weight above a fault or removing it, could suppress or trigger an earthquake.

This is a simplified explanation. The reality gets a bit more complicated. For one thing, the weight of a glacier does more than just press down on what's immediately below it. "When you press your hand into the couch, [the fabric] doesn't just go down under your hand, it stretches out, too," Susan Hough says. Stretching the Earth's crust, and slowly letting it rebound back, could also trigger seismic activity. It's one theory—appealing, but still unproven—for why faults like North America's New Madrid experience seismic activity despite being hundreds of miles from a plate boundary.

What's Climate Got to Do With It?

By now, you should see where this is going. If naturally melting glaciers can trigger earthquakes, it stands to reason that a glacier that melts because of man-made climate change could do the same thing. Yes, it's a reasonable assumption. But ...

There are a couple of caveats that you need to keep in mind. First off, while we know that changing climate has triggered seismic activity in the past, we don't really know yet how much seismic activity is likely to be triggered by contemporary, anthropogenic climate change. The effects still need to be quantified in this particular context.

Second, this effect might be happening already, but not in a way that has a big impact on most people. Bill McGuire of University College London and Patrick Wu, professor of geophysics at the University of Calgary, are two of the researchers really paying attention to the particular problem of seismic activity triggered by modern climate change. They both say the effect, so far, has been small—limited to low-level clusters of earthquakes in Alaska and around Greenland. In other words, where the glaciers, ice pack, and snow are melting. It's possible that we could see effects in other places—remember, weight on the crust stretches, it doesn't just compress—but we don't know that yet.

Third, Patrick Wu says it's unlikely that any really large earthquake, the magnitude 8's and up, would have a link to deglaciation. The earthquakes triggered by melting water tend to be smaller, he says, between magnitudes 5 and 7. Just because climate change can trigger earthquakes doesn't mean that every (or even most) earthquakes are triggered by climate change. Simple plate tectonics is still the primary force.

Nor can deglaciation trigger earthquakes in places that weren't at least somewhat earthquake-prone to begin with. "Deglaciation can't cause a crack. Tectonics can actually cause a crack, make a fault," he says. "Whenever there is glacial melting, faults can be reactivated. But it can't create the faults."

Finally, you can't look at the research being done by people like Wu and McGuire, look at the news, and go, "A-ha!" While these researchers are finding small increases in small, localized earthquakes in the far North, there's not actually been any dramatic, mysterious uptick in earthquakes that needs to be accounted for by this, or any other, theory.

The truth is, we've had several really big earthquakes in a relatively short period of time—Sumatra in 2004, Chile in 2010, and Japan in 2011. That's more than is normal. But not so many that the difference can't be accounted for by chance. And the broader frequency of earthquakes hasn't actually changed.

What has changed is our awareness of earthquakes, and their impact. Since the 1970s, we've had the technology and interconnectedness to reliably trace and report the vast majority of quakes that happen everywhere. Quakes that you'd have never known about 50 years ago are now on the evening news. And, more importantly, those quakes can appear to be more deadly because cities have gotten larger, allowing one earthquake to kill a lot of people in a relatively small area. All of that means that, watching the news, we perceive a bigger uptick in major earthquakes than there actually has been, according to the less subjective definition of "major" used by geologists.

Basically, it boils down to this: Climate change can trigger earthquakes. There's evidence that naturally occurring climate change did that in the past. There's some evidence that anthropogenic climate change might be doing that today. And there's evidence that we could see more climate change-related earthquakes in the future. But, if you're actually concerned about evidence (and you should be) then you can't go around, pointing to earthquakes that make the news today, and calling them consequences of climate change. And we can't oversimplify research to the point of forgetting all the yesbut.

For more information, check out Bill McGuire's 2010 summary of climate forcing of geological hazards, published in the Philosophical Transactions of the Royal Society. You can also find several of Patrick Wu's papers on his website.

Image: Earthquake damage - Bridge Street., a Creative Commons Attribution Share-Alike (2.0) image from 23934380@N06's photostream

Published 11:13 am Thu, Aug 4, 2011

, , , , , , , , ,

About the Author

Maggie Koerth-Baker is the science editor at BoingBoing.net. From August 2014-May 2015, she will be a Nieman-Berkman Fellow at Harvard University. You can follow Maggie's adventures in the Ivory Tower by subscribing to The Fellowship of Three Things newsletter.

37 Responses to “Climate change and earthquakes: It's complicated”

  1. anansi133 says:

    As long as this story is about planetary science in a way that has nothing to do with me as an individual- I am fascinated.

    It’s when the emotional stuff kicks in- “Humans can’t possibly impact something as big as a whole planet” and “This civilization doesn’t know how to live here responsibly”- the science starts to seem irrelevant. How much certainty must we have before there is a decision to change the way things are done?

    • SKR says:

       You do realize that the scientific method was basically created in order to take the emotional stuff out of consideration, right?  The science is completely relevant to the questions as to whether humans are impacting the entire planet or are behaving responsibly. Without science we would just have a bunch of crying indians instead of actual data with which to make risk assessments.

  2. gordonjcp says:

    You get a lot of “climate science deniers” on both the pro- and anti-global warming sides.  Just sayin’

  3. hooeezit says:

    Maggie, when are you doing the promised meetup in Minneapolis, or did I miss it already? Your articles truly expand my horizons, and I’d love to meet you in person before I leave Minneapolis in 6 weeks! Thanks for venturing into the arcane and curious.

  4. Maggie Koerth-Baker says:

    We did a meetup in June. I’ve been meaning to plan another one for September (after the summer cabin/social season is over), but haven’t quite gotten around to it yet. Thanks for putting my feet to the fire!

    And thank you for the kind words about my work! I appreciate that.

  5. Adam S. says:

    I think I heard about some research that certain extra high tides could also get involved in triggering earthquakes. The extra weight of the water of high tides moving against a fault.

    If there was anything to that, the ice caps melting would free up even more water to move around during tides.

  6. Lobster says:

    These kinds of articles always give me a bit of a headache.  There might be some scientific value here, despite the yesbut… but we already have a huge portion of the population that doesn’t even believe the climate is changing at all.  Every time you suggest some other dramatic effect, they’re going to think the whole theory is even more ridiculous, and that them egghead ivory tower scientists think they’re even dumber. 

    I guess that’s how science works, though.  It’s not about PR.  

    • greebo says:

      I don’t see why this would give you a headache – Maggie explains it beautifully. Big ice sheets are very heavy – you melt them and the earth’s crust rebounds. It’s happened before in the earth’s history, but we don’t yet have clear data to show it’s happening today. If climate change increases, there’s a good chance it will happen.

      The only way you get from here to “they’re going to think the whole theory is even more ridiculous” is is you assume people won’t switch on their brains first. Or that they will eschew simple clear explanations and prefer instead the obfuscation put out by the denialist machine. The antidote to the latter is more articles like this one.

      • Lobster says:

        Yes, it’s not the theory but the consequences.

        Do you think it’s unreasonable to assume people won’t switch on their brains first, or that they won’t eschew simple clear explanations in favor of the ones they already believe from the denialist machine?  I’d love for you to be right, but personal experience would suggest you’re not.

    • billstewart says:

      There are at least three reasons for large parts of the public not to believe in climate change
      – It’s a fairly radical concept that could have major impacts on our lives.
      – It’s really depressing
      – There are large companies that will lose lots of money if the government starts making climate-change mitigation laws, and it’s financially worthwhile for them to put lots of PR money into getting the public not to believe in it.  Some of that goes directly into climate change propaganda, some goes into anti-evolution propaganda or into other “don’t believe liberal scientists” propaganda, and some into political parties that encourage those messages.  

      People need to remember recent events like the Dust Bowl, and they need to look at the part of the world that used to be known as “The Fertile Crescent” and how it’s mostly desert now.

      • Lobster says:

         I agree with you.  My concern – one to which I’ll readily admit all solutions seem to be dishonest or unethical – is that moving the goal posts further out is only going to make those people harder to convince. 

        Then again, I’d also ask why it matters if we convince them in the first place.  It doesn’t matter what the average person believes.  It’d be nice if they understood science and agreed, but the average person has little to no impact on how this is going to turn out. 

        Instead of trying to convince the deniers, a scientist’s time is better spent trying to mitigate the damage.  There is no greater indicator of success than the denier’s ability to continue to deny. 

        So I guess in the end I’m glad for this article.  Still, I do not look forward to the arguments. ;)

    • Mary Dicerni says:

      To Lobster, Whether it is climate change or possibly even man-made, I think we should be doing the right thing, and like good landlords or tenants, be clean and proper with garbage etc, and stop producing crazy plastic containers that we have enough of, and recycle and keep it tidy. So much nuclear waste, and general garbage, even in the ocean, is a pathetic way for man to live.  Now GMO and toxins in everything,  war everywhere, mostly still about religion and oil…money, greed, money, war, money, bad doctors, money, famine. Why are we allowing this ? What has climate change to do with how we all behave ?  As the regular person on a planet, how did we allow this? Probably because we believed what we heard, and it may be a lot of propaganda, while we go on playing the game of life. They distract us from the pains of war, and pretend to be santa claus most of the time. I do not think there is much difference in the parties, but there  are many hidden truths with those who run the government, no matter who is voted in. Those who are doing well at home, and with their jobs and their wallets in tact, may never notice things like war or climate change, or how much garbage we are creating , that cannot be recycled. Who produces these things ? Why are they allowed to continue ? The research about the faults can also be engineered with a small bomb, creating waves in the sea. How much can be engineered, and who can research what man can do ? Who do you believe ?

      • Lobster says:

        While I see your point, Mary, if you always look at the big picture it becomes very difficult to solve any one problem.  Yes, there is war.  Yes, we are poisoning the planet.  Yes, we are easily manipulated.  If you know a way to solve all of those problems at the same time, I’d love to hear it.  Otherwise, maybe we should take things one step at a time.

  7. EricT says:

    The book Jonathan Franzen wrote before he wrote The Corrections, Strong Motion, addresses the issue of man-made impacts on tectonic shifts in some interesting ways.  It has a chemical company illegally dumping toxic waste into empty oil wells to result in increased seismic activity.  It’s set in Boston, if I remember correctly.   

  8. langeslag says:

    Hey that’s a fantastic article Maggie, many thanks!

    I’d never have thought there could be a connection at all, and now I feel I’ve gained more nuance on the issue, which I didn’t know was an issue.

  9. grandmapucker says:

    A lady on the train I take to work was loudly going on and on the other day about how all the earthquakes and tsunamis are obviously caused by the black hole at the center of the galaxy, not climate change.

  10. Teller says:

    Living in California, I take issue with ‘not causing the really big ones – just those between 5 and 7.’ The 7 can rock.

    • penguinchris says:

      Yes but in geologist’s terms a 7 is big, but not “really big” – an increase of two in magnitude indicates 1000 times more energy released (i.e. a 7 is 1000x more powerful than a 5).

      So yes, a 7 can rock (heh heh), but high 8’s or 9’s are 1000x more than that!

      BTW IAAGWLIC (I am a geologist who lives in california).

    • Nicholas Laidler says:

      Technical definition of a Large earthquake to a seismologist, 7.0 or larger. http://earthquake.usgs.gov/learn/faq/?faqID=24  A much smaller quake has the potential to level almost any city, just look at what happened to Christchurch with a 6.3.  What’s deceptive about this scale is that it’s logarithmic, there’s about 32 times the energy released for each 1 increment on the scale.  Sure, it’s just semantics where you change the ‘name’ of the earthquake type, but that’s where the misunderstanding comes in.

  11. Emo Pinata says:

    What I learned – we have no idea what can be causing all these problems, but it has to do with weight. That means population growth, a fatter population, stripping, and industrialization are all causing seismic activity. It’s a “yes, but” line and the “but” is a massive “but”. It just sounds like “it’s one of many, many factors that causes seismic activity” is a better way to answer the question than the more fear-inducing (regardless of intent) statements I have seen.

    Sort of like how reducing your carbon footprint effects “one of many, many factors that cause climate change”. The problem with all of these massive problems is that there is not a single massive absolute source to tackle and move on to the next problem like we’re checking off our “honey do” lists.

    It will take massive societal, technological, and environmental change to even come close to both understanding and improving climate change. We need to put more effort into stabilizing the world’s population, improving efficient energy and resource use, and make huge strides in how we approach our environment.

    I still think over-fishing and resource stripping are bigger issues than climate change as well.

    • PeterK says:

      I think your sense of scale is off.  What you should have learned is that a persons weight, overpopulation, or even industrial growth (outside of reservoirs) have nowhere near enough mass to affect seismicity.

      • Itsumishi says:

        I’m sure you’re right, but because I feel like esquivalating

        Lets take Manhattan as a rough example.

        Apparently the average weekday “day time” population of Manhattan is 2,874,003 (crappy source: http://www.quora.com/How-many-people-are-on-the-island-of-Manhattan-on-an-average-weekday)
        We’ll estimate the average person weighs about 80kg (177.65 pounds) (averaged from this source: http://usgovinfo.about.com/od/healthcare/a/tallbutfat.htm)

        So that’d be roughly = 229,920,240Kg or 506,887,362pounds for the total populations weight.

        Apparently The Empire State Building weighs roughly 365,000 tons or 730,000,000pounds or 331,122,430kg. (http://www.newyorktransportation.com/info/empirefact2.html)

        And there are roughly 140 skyscrapers in Manhattan… ESB is probably a lot heavier than most (being older, built out of heavier materials and is currently the tallest building). We’ll assume for the sake of back of the envelope calculations that its twice the average weight. So 730,000,000 x 70 = 51,100,000,000 pounds or 23,178,570,107kg.

        Add in the cars… Apparently there is roughly 1 car to every 2 people in NYC (http://en.wikipedia.org/wiki/Transportation_in_New_York_City#Private_automobiles) and Manhattan’s residential population is  1,537,195 so that’d be roughly = 768597… 
        The average US car weight approx = 4000pounds. 
        So… 3,074,388,000pounds or 1,394,518,939kg…

        Because I really probably should be doing work, I’ll completely guess the weight of the rest of the infrastructure from buildings, to roads to subway systems is exactly twice the (highly scientifically estimated) weight of the skyscrapers… 102,200,000,000 pounds or 46,357,140,214kg.

        ————-

        So the total of my very rushed, completely inaccurate estimate of the daytime weight of Manhattan is…

        229,920,240kg (people) +  23,178,570,107kg (skyscrapers) + 1,394,518,939kg (cars) + 46,357,140,214kg (everything else) = 71,160,149,500kg or 156 881 275 360pounds.

        All over an area that is 59.5 km2

        —–

        For comparison the Konya damn has a capacity of 2,797,400,000 cubic metres or roughly the same in litres. A litre of water is roughly a kg of water so it’d be roughly 6 167 211 322 pounds (Source: http://en.wikipedia.org/wiki/Koyna_Dam)

        Therefore… The human element of Manhattan weighs 68,362,749,500kgs more than the Konya damn. 

        The Konya damn is 891.78 km2 or shit loads more spread out than Manhattan….

        —-

        Well after that very rough approximation I conclude that Metropolises weigh more than damns of equivalent sizes. I retract my support for your hypothesis.

        • Nicholas Laidler says:

          Haaa, I love it when Creationists and climate denialists try maths :-) Itsumishi, you’re only off by a few orders of magnitude.  I was going to respond directly to this, but PeterK beat me to it, good work that man :-)

          Getting back to the point of the article, climate change – melts ice caps – isostatic rebound – earth quakes, and depending on their location they have this habit of triggering big submarine landslides, which in turn may trigger tsunamis.  These earthquakes are
          not caused by the same forcing mechanism as plate boundary earthquakes, that are the result of plate tectonics.  A small scale example that people like to throw around to illustrate how adding weight on top of the crust causes earthquakes, are dams.  The argument from Itsumishi is whether highly urbanised areas could add more weight to a section of crust than the dam used in the example, and Peter K got it right, dam beats people, BUT ice sheet beats all… by quite a lot.

          Let’s say the Greenland Ice Sheet melts, using numbers from Wikipedia, that’s an area
          of about 1.7 million square kilometres and a volume of about 2.85 million cubic kilometres.  Use a density of 0.98 g/mL for ice and that’s a mass in the order of 10^15 kg.  Suddenly arguing semantics about Manhattan and a dam seems a little nutty, even sillier when you can’t convert units properly and get your conclusion about arguing dams and cities wrong.

    • Nicholas Laidler says:

      With all due respect, bollox.  I’m going to read the statement “we have no idea what can be causing all these problems, but it has to do with weight” in context to mean, we don’t know why earthquakes happen. We know what processes apply force throughout our planet and how stuff deforms.  Seismologists, geotechnicians, geophysicists, materials engineers, structural geologist and a good deal more professionals have put great efforts into understanding, measuring, modelling and describing (with complicated stuff like maths equations /massive sarcasm) the behaviour of material in response to stress.  We use this information every day, we know if a bridge will stand before we build it, we know how rock, steel, sand and concrete will behave, just as I can work out how a rock will behave under certain stress conditions.  Merely because you do not know how the planet round you functions does not mean “we” do now know how it works.  “We” in fact have a damn good idea about how the geosphere works, how the atmosphere works, how they interact with each other and are influenced by what we do to them.  

      “The problem with all of these massive problems is that there is not a single massive absolute source to tackle”, Really? This comes as a surprise to you?  There’s more than one thing going on around you at any one time?

      “It will take massive societal, technological, and environmental change to even come close to both understanding and improving climate change.”  You can check off ‘understand climate change’, that was the easy bit.  It’s the bit getting people who can’t understand all the calculus behind the ‘understanding climate change’ to accept what scientists say.  As for getting something done about it, you can lead a horse to water….

  12. Chris S says:

    Anyone who grew up in Southern Ontario paying attention to local geography would know about the Niagara Escarpment. The escarpment and the local water structures are deeply influenced by the loss of the Wisconsin glacier only 12,000 years ago. Isostatic rebound can do amazing things!

    http://en.wikipedia.org/wiki/Post-glacial_rebound

    Even our current ice loss causes this to be quite noticeable in some areas — http://www.nytimes.com/2009/05/18/science/earth/18juneau.html

  13. crummett says:

    It’s complicated? Then it doesn’t exist. (hands on ears) lalalala!

  14. $15017138 says:

    There’s a lot of emerging science re earthquakes. Changes in the ionosphere days before quakes like Japan and talk of solar activity, radon, or some other cause. A quake will be predicted soon. These guys are already covering parts of California, Oregon and Washington – quakecasts.com. The Japan quake is the most studied and analyzed in history and will teach us a lot.

    • Mary Dicerni says:

      Was anyone able to predict the Japan quake ? Or was it a total surprise ? How would one tell the difference between an engineered quake and an expected one ? What could they learn from an earthquake that was engineered with explosives, etc.?? Is there any research on this type of activity ? 

      • $15017138 says:

        Nobody predicted the Japan quake BUT in analyzing satellite data after the quake it became apparent that the ionosphere was changing dramatically in the days leading up to it in terms of TEC (electron concentration) and heat. This company (quakecasts.com) is searching the ionosphere over the U.S. West Coast for similar signatures. Nobody is sure WHY the ionosphere acts up – solar, radon, p-holes, acoustic gravity waves, etc. – but it is and there is growing evidence this could be the path to predicting them much the way learning about barometric pressures, wind sheer, etc., helped meteorologists start predicting hurricanes.

        • Lobster says:

          If this turns out to be true then that’s wonderful.  Maybe we could even figure out a way to track those animals that seem to sense when a quake is coming, or at the very least figure out what is setting them off. 

          However if this does not turn out to be true, then it’s nothing more than anomaly hunting.  

          • $15017138 says:

            Right – anomalies are always the precursors to any new discovery be they genetic mutations lurking behind disease or previously unrecognized patterns in the ionosphere suggesting the build up of tectonic pressures.

      • Nicholas Laidler says:

        Yes it was predicted, why do you think Japan has highly earthquake resistant building standards?  We know pretty damn well WHERE earthquakes will happen, plate boundaries, mantle hot spots, the kind of places plate tectonic’s predicts them to be.  WHEN and HOW BIG they’ll be is a little more difficult, we can give estimates like magnitude 8.0 quake with a repeat period of about 200 years.  But the limits on these estimates are still pretty loose and largely (but not exclusively) based upon statistical studies.  A statement like and 8.0 with a repeat period of 200 years also DOSE NOT mean there will be an 8.0 every 200 years, just an average rate, so it is entirely possible to get two 8.5’s in two weeks followed by 450 years and then a 7.5.

  15. PeterK says:

    Not to be too esquivalatish, but there are 1000 liters in 1 cubic
    meter.  And I am not sure subway infrastructure adds much weight, as
    they removed rock and replaced it with mostly air.  But even using your values
    (while factoring in the cubic meters to liters conversion), Manhattan
    ends up weighing 1/3 less per square kilometer than Konya Dam. 
    Manhattan at 1.2×10^9 kg/sq.km vs Konya Dam at 3.1×10^9 kg/sq.km.

    I
    reiterate my support for my hypothesis that the weight of humans,
    especially as it relates to increasing population and epidemic obesity,
    does not cause earthquakes.

    If you are looking for a
    anthropogenic link to tsunamis, you would be better off looking at how
    increasing ocean temperatures are affecting subseafloor methane hydrate,
    and the subsequent dissociating hydrates effect on slope stability.

  16. masamunecyrus says:

    The Earth is always under a continuous amount of stress and pressure. Not only is it under huge stresses from convection in the mantle, moving plates, etc, but the whole Earth itself has tides–it wobbles and expands and contracts and breaths in several different modes.

    Earthquakes are a way for the Earth to relieve stresses when said stresses accumulate enough to fracture the rock that is stressed. Changing the stress in an area can cause earthquakes. Man-made dams can and do cause earthquakes. Earth tides and ocean tides and even rainfall can be correlated to increased earthquake activity in some area. Basically, the earth is always ready to break somewhere; by adding a little weight here or there–who knows–that added weight may have been the last straw which fractures the rock.

    So it does stand that climate change can cause earthquakes. But given the political circumstances of today, saying such a thing is misleading. Change in stress causes earthquakes. If the Earth died and everything completely stopped, earthquakes would probably end in some hundreds of millions or billions of years as all of the stresses balance out everywhere within the Earth. But the Earth isn’t dead; it is always changing. If the Earth gets warmer, earthquakes don’t care. But if some ice melts, removing weight from one area and adding it to the next, maybe it will induce an earthquake. Or if the earth gets colder, ice accumulates in some area adding weight and stress, and it may induce an earthquake.

    Additionally, earthquakes are going to happen from tectonic activity whether you like it or not. With or without global warming or any kind of climate change, as long as the plates keep doing what they’re doing, you’re going to have giant earthquakes in certain regions. A cooler Earth wouldn’t have prevent the Japan earthquake. The best you’ll get is perhaps a cooler Earth would have done something to the tides, which would have stressed the fault in some different way and it would have ruptured at 2:30pm instead of 2:46pm.

  17. Interesting that I haven’t heard about the possible earthquake/climate change connection from any environmental groups (and I work for one).  I’d guess that’s because there are plenty of brutal climate change impacts already well documented and visible with more obvious connections to a changing climate.

    Anyway, thanks for the write up.

  18. Chris Watts says:

    I think you meant “divot”.