Earthquakes of the 20th Century



Published on Dec 9, 2018

This animation shows every recorded earthquake in sequence as they occurred from January 1, 1901, through December 31, 2000, at a rate of 1 year per second. The earthquake hypocenters first appear as flashes then remain as colored circles before shrinking with time so as not to obscure subsequent earthquakes. The size of the circle represents the earthquake magnitude while the color represents its depth within the earth. At the end of the animation it will first show all quakes in this 100-year period. Next, it will show only those earthquakes greater than magnitude 6.5, the smallest earthquake size known to make a tsunami. It will then show only those earthquakes with magnitudes of 8.0 or larger, the “great” earthquakes most likely to pose a tsunami threat when they occur under the ocean or near a coastline and when they are shallow within the earth (less than 100 km or 60 mi. deep). The animation concludes by showing the plate boundary faults responsible for the majority of all of these earthquakes.

The era of modern earthquake seismology—the scientific study of earthquakes—began in the 20th Century with the invention of the seismometer and its deployment in instrument networks to record and measure earthquakes as they occur. Therefore, when the animation begins only the largest earthquakes appear as they were the only ones that could be detected at great distances with the few available instruments available at the time. But as time progresses, more and more seismometers were deployed and smaller and smaller earthquakes could be recorded. For example, note how in the 1930’s many small earthquakes suddenly seem to appear in California, but this illusion results from the installation of more and more instruments in that region. Likewise, there appears to be a jump in the number of earthquakes globally in the 1970’s when seismology took another leap forward with advances in telecommunications and signal processing with digital computers, a trend that continues today.

20th Century seismology revealed the global geographic distribution of earthquakes and helped to solidify the Theory of Plate Tectonics. Notice how earthquake epicenters do not occur randomly in space but form patterns over the earth’s surface, revealing the boundaries between tectonic plates as shown toward the end of this animation. This time period also includes some remarkable events, including those that generated devastating tsunamis:

8.8 — Ecuador — 31January 1906
8.4 — Kamchatka, Russia — 3 February 1923
8.4 — Sanriku, Japan — 2 March 1933
8.6 — Unimak Island, Aleutian Islands — 1 April 1946
9.0 — Kamchatka, Russia — 4 November 1952
8.6 — Andreanof Islands, Aleutian Islands — 9 March 1957
9.5 — Valdivia, Chile — 22 May 1960
9.2 — Prince William Sound, Alaska — 28 March 1964
8.7 — Rat Islands, Aleutian Islands — 4 February 1965

These earthquakes represent some of the largest ever recorded. Note how they all occur at a particular type of plate boundary, subduction zones where tectonic plates collide, so these are the regions where we expect future devastating tsunamis to be generated.


48 thoughts on “Earthquakes of the 20th Century

  1. Earthquakes and volcanoes are a result of the liquid on which the tectonic plates float. That also gives rise to the magnetic field which makes Earth habitable. Mars is different. link

    In a sense, we have to be grateful for earthquakes. 🙂

    • Does a liquid permit accrual and storage of elastic strain? Does crust full of water and phyllosilicate mineral lube and pervasive jointing enable accrual and storage of regional elastic strain, in such a discontinuous medium? I’d say no one has identified the real mechanism of earthquake generation as yet in the lubed-up discontinuous geology. We presume elastic energy must be the mechanism as it’s a convenient working ‘truth’, but that still ain’t it.

    • Don’t remind me. I hope to be posthumous by the time it hits, but there’s a better chance of me seeing it than seeing RCP8.5 come true. I suppose if one has to worry to pass the time, then another New Madrid quake might be more “worthy of worry” due to the projected scenario of its continental impacts.

      • I read a novel about a repeat of the New Madrid earthquake in modern times. (I can’t remember the name or the author) but it was pointed out that it would be more devastating than “the Big One” in California. 1-because there aren’t a lot of secondary faults to dampen the energy the damage would be spread over a much wider area. The New Madrid earthquake caused damage in Charleston SC and rang church bells in Boston. 2-Nothing is built with an earthquake as a possibility and there is a LOT of reinforced masonry buildings in the Mississippi-Missouri valleys. 3-There are a lot of oil storage terminals and chemical plants along the Mississippi river, a repeat would turn the Mississippi into a caustic, flaming sewer. And finally, most of the major gas and oil pipelines from Texas go through that area and all would suffer many major fractures with resulting fires and explosions.

  2. It sort of misleads, though, because instrumentation becomes better. You can really see the result around the mid 1970’s when we suddenly see the number of very small quakes in remote regions begin to appear. They should have probably cut off the bottom end to only felt quakes.

    • “instrumentation becomes better”

      That’s about it. Part of my job is to meticulously document each nuance of a change in collecting data (which is partially what brought me to WUWT and Climate Audit, etc.: nobody else seems to be doing this with climate change, certainly not the media).

      That’s for me in CYA mode.

      For my managers who either grin like Cheshire Cats, or looked stunned when they run historical data…well, if I like them, I share. If I don’t…

    • I figure one could plot that seismic increase (due to instrumentation changes) against the MLO CO2 and get a pretty high R^2.

    • Crosspatch – using the same logic as the anthropogenic climate change ‘evidence’ the increasing numbers of earthquakes in recent times are a result of increasing CO2. How long will it take for climate alarmists to link the two?

    • Funny. That scene is nothing like the book. In the book, Victor creates his monster, then goes to bed, hoping it will all just go away. Really bizarre.

      • Director or someone seemed to know what they were doing…created one of the more memorable and repeated lines in movie history.

  3. I wouldn’t want to extrapolate that trend very far.

    Fun to watch.

    New Zealand just disappears by the end.

  4. Earthquakes are more interesting than you would think.

    There is a paradox concerning the 200% twenty-year increase in mid-ocean earthquakes, all over the planet.

    The paradox is the plate tectonic movement must be caused by a force. The plates are massive objects. There must be a massive force to move the plates. The 200% increase in mid-ocean earthquakes requires the massive force to increase all over the earth.

    The traditional tectonic plate force mechanism was hypothesized to be caused by mantel movement. Observations however show the only mantel movement is that caused by the tectonic plates moving.

    What is interesting is the geology does not have a hand waving explanation as to what generates the force that moves the tectonic plates, before the observation that mid-ocean earth quakes increased by 200% average for 20 years.

    The lack of a forcing mechanism explains why the theory of plate tectonics took so long to be accepted.

    There is no mechanism in the current geological paradigm to explain the sudden simultaneous increase in force at each ridge to cause the increase in mid-ocean ridge spreading. In a separate review papers, it has noted that there is evidence of massive concentrated compressive forces at mid-ocean ridges that is roughly two orders of magnitude greater than the standard geological tectonic plate force paradigm can explain.

    Namely, increased seismic activity in the HGFA (i.e., the mid-ocean’s spreading zones) serves as a proxy indicator of higher geothermal flux in these regions. The HGFA include the Mid-Atlantic Ridge, the East Pacific Rise, the West Chile Rise, the Ridges of the Indian Ocean, and the Ridges of the Antarctic/Southern Ocean. This additional mid-ocean heating causes an acceleration of oceanic overturning and thermobaric convection, resulting in higher ocean temperatures and greater heat transport into the Arctic [2,3]. This manifests itself as an anomaly known as the “Arctic Amplification,” where the Arctic warms to a much greater degree than the rest of the globe (Table 1) [4,5].

    Nitecki et al. (1978) reported that in 1961 only 27% of western geologists accepted plate tectonics, but that during the mid-1960s a “chain reaction” took place, and by 1977 it was embraced by as many as 87%. Some
    proponents of plate tectonics have admitted that a bandwagon atmosphere developed and that data that did not fit into the model were not given sufficient consideration (e.g., Wyllie, 1976), resulting in “a somewhat disturbing dogmatism” (Dott and Batten, 198 1, p. 15 1). McGeary and Plummer (1 998, p. 97) acknowledge that “geologists, like other people, are susceptible to fads.”

    The driving force of plate movements was initially claimed to be mantle deep convection currents welling up beneath midocean ridges, with downwelling occurring beneath ocean trenches. Since the existence of layering in the mantle was considered to render whole-mantle convection unlikely, twol ayer convection models were also proposed. Jeffreys (1 974) argued that convection cannot take place because it is a self-damping process, as described by the Lomnitz law. Plate tectonicists expected seismic tomography to provide clear evidence of a well-organized convection-cell pattern, but it has actually provided strong evidence against the existence of large, plate-propelling convection cells in the upper mantle (Anderson, Tanimoto, and Zhang, 1992).

    Many geologists now think that mantle convection is a result of plate motion rather than its cause and that it is shallow rather than mantle deep (McGeary and Plummer, 1998).

    Plate Tectonics: too weak to build mountains
    “In 2002 it could be said that: “Although the concept of plates moving on Earth’s surface is universally accepted, it is less clear which forces cause that motion. Understanding the mechanism of plate tectonics is one of the most important problems in the geosciences”8. A 2004 paper noted that “considerable debate remains about the driving forces of the tectonic plates and their relative contribution”40. “Alfred Wegener’s theory of continental drift died in 1926, primarily because no one could suggest an acceptable driving mechanism. In an ironical twist, continental drift (now generalized to plate tectonics) is almost universally accepted, but we still do not understand the driving mechanism in anything other than the most general terms”2.”
    “The advent of plate tectonics made the classical mantle convection hypothesis even more untenable. For instance, the supposition that mid-oceanic ridges are the site of upwelling and trenches are that of sinking of the large scale convective flow cannot be valid, because it is now established that actively spreading, oceanic ridges migrate and often collide with trenches”14. “Another difficulty is that if this is currently the main mechanism, the major convection cells would have to have about half the width of the large oceans, with a pattern of motion that would have to be more or less constant over very large areas under the lithosphere. This would fail to explain the relative motion of plates with irregularly shaped margins at the Mid-Atlantic ridge and Carlsberg ridge, and the motion of small plates, such as the Caribbean and the Philippine plates”19.

  5. For sure, some of the changes we see in this are down to better measurement, but it’s like watching an
    animation of the history of the subject.
    It’s great to watch the oceanic spreading ridges lighting up as the years go by post c. 1950.
    My job is meat-and-potatoes corporate IT infrastructure, but this sort of graphic is a joy.
    Data presented in a way that makes it clear what’s going on.
    Good stuff.

    • Everything after a certain date, as stated in the OP, is due to seismometer networks expanding. Almost exactly the same as doppler networks for detecting tornadoes.

  6. Great animation, showed it to some friends and they were pretty amazed at it.

    Stick to decent science NOAA!~!!

    • 20 years ago there was a free downloadable program produced by the Smithsonian during the late 1990s called “SeisVol” which had a 3D display perspective, wherein you could look at any seismically active fault surface trace (delineated by the quake data) from any direction and distance, and see the entire seismic record above mag-3 play back at any speed or even in reverse. It was fully customizable and even updated itself online with any new quake data every few weeks. You could even download 30 second arc topo and benthic data for it, and ‘fly’ along a fault as quakes played on it. You could even vies a fault from below and map the shape of it and take screens of it. It looked brilliant once fully tweaked and it’s display was far superior to what’s being shown above.

      All this stuff has been done, and done much better – decades ago.

  7. I can’t explain what the basic cause might be, but wonder if there is the shift in Length of Day either up or down would shift the pressure at the plate boundries, causing more or less earthquake activity.

  8. Had the privilege of meeting Robert Felix ( ) for lunch last fall near Seattle. He mentioned that he planned to move to Texas within a year. Said (iIrc) he had a hunch that things were shaping up to make this an opportune time. Based on a blog post titled “Making my actions match my words” on 4/15/19, he has done just that.

    Wishing Bob and his wife the best of luck in their new home.

  9. This interesting animation also inadvertently reveals the effect of a non-uniform capability in sensing earthquakes throughout the globe. That’s what creates the misleading impression that earthquakes are occurring more frequently as time progresses. Meanwhile, it’s noteworthy that Mag 8 quakes seem clustered around the third quarter of the last century.

  10. My thoughts have been taken by earthquakes recently. Specifically by the quake history of the New Madrid Seismic Zone, and that led me to write a post which I just reworked for better clarity. Here is what I came up with. Thought about making it a post, but it fits here as well so.

    New Madrid Fault Zone 2019 Prediction

    This post has to do with the possibility of the next large quake on the New Madrid Fault hitting the Midwest towards the end of this year. I have outlined the main reasons why I have come to this conclusion below. I have spent the last 11 years studying climate related material. I became interested in quakes after the Great Tohoku Quake in March
    JGU 09_geo_tree_ring_northern_europe_climate.jpg JPEG Image 1873 × 726 pixels Scaled 94 900 AD
    JGU 09_geo_tree_ring_northern_europe_climate.jpg JPEG Image 1873 × 726 pixels Scaled 94 300 AD

    2011. This is how and why I eventually came to read about quakes on the NMSZ. From there I could not help but notice that all of the large quakes on the NMSZ had a connection. That was that the main correlation is always related to the longer term solar cyclical events known as a Gleissberg cycle, solar grand minima, and the 11 year solar cycle. both 300 AD and 900 AD are represented on the left side of the pics

    The first major quake recorded on the New Madrid was at 1pm on December 25th of 1699, as noted by a French missionary in a group of explorers. This happened during the Maunder Minimum, and also during the latter stage of a solar minimum. Dec 11th of 1811 was the next of a series of 3 large quakes on the New Madrid. The second quake was on January 23rd 1812, and the 3rd and largest struck on February 7th 1812. This takes place during the Dalton Minimum, and right at the low point of SC 5.

    Other approximate years with large quakes on the NMSZ were in AD300, AD900 and AD1450. Now take a look at the JG/U 2K temp graph and see what it shows is happening to global temps for each of those 3 quakes. All three occurred during an obvious down turn in global temps. The year 1450 is a recognized grand minimum. The other two are at the very least a Gleissberg cycle. The one around 300 AD is certainly a GM which looks like it would have rivaled the Maunder GM. It affects temps for around 60 years. The sharp drop around 900 AD is what I would call a quarter note of around 15 years in length, and so likely a Gleissberg cycle. It would be interesting if it the state of the solar cycle could be determined to see if those 3 large quakes happened in the midst of the solar minimum. Other moderately strong quakes were on January 4th in 1843, at the solar minimum, and on October 31st 1895. This last one occurs after the maximum of SC 13 and 8 years prior to the solar minimum. Most recent was on November 9th 1968 two plus years after the solar minimum. An interesting footnote is that this occurs around 3 or 4 months after the peak of SC 20 when sunspots rapidly drop 60% from that peak as seen on Dr Svalgard’s high res ssn graph. …

    So commonality with all of the major quakes on the NMSZ is they all strike mainly in the winter, close to or during the solar minimum, and either during a solar grand minimum, during a Gleissberg cycle, or in the last case after a rapid plunge in sunspots. Which raises the question in my mind is the next New Madrid quake now close at hand and ready to strike in this upcoming winter? If not this winter, then potentially next winter which would place it slightly after the end of this current minimum. It is clear to see that this year 2019 will be the heart of the solar minimum. The solar minimum is certainly low and prolonged as the last one was in 2008/09. In 2008 a moderately strong quake hit on the Wabash Fault Zone, close to the New Madrid Zone. Alternatively the solar minimum at the end of SC 25 will be the next likely timing for a large quake on the NMSZ, if SC 25 remains as low or lower than SC 24. Does this warrant issuing a warning to the proper emergency agencies to be on stand by alert, and/or to issue a general alert to the population at risk?

    • Should have looked at what Dr Svalgaard’s high res ssn graph shows for that quake on October 31st of 1895, the last large quake on the New Madrid. Sunspots had fallen to a low point at that time. Did the last Gleissberg also start at that time, or was that a few years later?

    • Tennessee had a 3.6 this morning. Watch out for this coming winter. This could be the real deal, although there is no way to know the intensity of a potential quake. The danger is that all of the known large quakes occur under current low solar conditions. An interesting offshoot idea from what I see in this is that the JG/U 2K temp graph could potentially be used as a method for finding previous unknown large quakes on the NMSZ.

      The older large quakes for which evidence has been found occurred in 300 AD, 900 AD, and 1450 AD. But why not around 540 AD where a steep temp drop which equals 1450 AD can be seen? Or around 420 AD? Or around 800 AD? Or around 1125 AD? Or around 1230 AD? Or around 1340 AD? Those are all sharp temp drops and most likely Gleissberg/GSM cycles. More than that, note how those years would fill in the blanks which would then show a large quake around every 100+ years, ie known 300, then 420, 540, 680, 800, known 900, 1125, 1230, 1340, known 1450. The rest is known 1699, 1811/12, 1895. An intriguing idea, no?

  11. Interesting how the number and frequency of earthquakes increased after the 1963 Nuclear Test Ban Treaty when both sides needed additional seismographs to detect the other sides underground tests.

  12. The reason scientists are having trouble with the mechanism is because they assume Pangaea was land floating in an ocean on an Earth of today’s diameter. All the pre-Cambrian and Cambrian fossils are of sea life–there WAS no land, then. In fact, timing of Sea-floor spreading proves that the Earth was perhaps half its present diameter and Pangaea was the entire sea floor long ago.

    This site once published research showing that a poor argument “inoculates” one against an idea, and a better argument is never or rarely accepted. There are hundreds of You Tube videos animating the Continental drift theory on a fixed diameter Earth ( I just checked.)

    You need a video that shows the Sea Floor Spreading timeline and runs the continents back in time by the scientific data. Such a video shows the continents coming together PERFECTLY all around the Earth. That is as close to total proof as it gets in science.
    One such is
    There are many biological and geological puzzles that will never be solved until this fact is taken into account.

    • Serious problem with that theory, where is the extra mass coming from? Earth does have an infall of material in the form of metorites, but the rate of accumulation can’t explain such an increase in Earth’s size.

      • “All the pre-Cambrian and Cambrian fossils are of sea life–there WAS no land, then.”

        That is a Big error in your logic. Lan animal and non aquatic plants had not yet evolve. So the main reason of all of the Cambrian fossils are are of sea live is because that is were all the life was.

        Geologist have been able to date rock radio active atoms that contain. They have found rock that was dry land a billion years before the cambrian. Geologist have found evidence of 11 supper continents The oldest dates back to about 3.6 billion years ago.. They appear to form, break apart, and reform. regularly.

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