Science predicted the Chile’s Earthquake

I am finally back, repairing some of the damages in our labs. The situation in Chile is not good. The deaths are raising slowly, but continoulsy, over 800 people now. Also, some data regarding thousands of missing people is also of great concern.

Regarding to science, several laboratories have reported serious damages, including lost of data, expensive equipment (you must consider that, due to the location of Chile, far from the manufacturers, equipments and reagents cost three or four times more expensive than in USA or Europe).

The observations and predictions (at a glance)

It is surprising that researchers had predicted the earthquake almost two years ago [1]. Teachers always say to students “nature is unpredictable; you can’t know where an earthquake will occur”. But technology advances, and together with mathematical modeling and observation, just like Darwin did in his travel to Chile almost 170 years ago, describing the earthquake of 1835 [2], researchers can formulate hypotheses about when, and how strong an earthquake will occur.

Ruegg and coworkers published a paper in “Physics of the Earth and Planetary Interiors” (Ruegg JC, 175:78–85, 2009). The team made observations in a range from 1996 to 2002, focusing in the area from Constitución to Concepción, since no major earthquakes occurred in that space since 1835 (described by Darwin). They measured the displacement of the plate (more exactly, the velocity of the movement). The results (at a big glance, since I am not a geologist) showed that coastal regions had a higher velocity compared with regions in the Andes area. Assuming that no major earthquakes released the accumulated force since 1835, a deficit of horizontal displacement of 10 m will have accumulated.

To Ruegg and coworkers, this could mean, in a worst case scenario, “that the southern part of the Concepción–Constitución
gap has accumulated a slip deficit that is large enough to produce a very large earthquake of about Mw = 8.0–8.5″.

What happened in Chile?

This February 27, at 3:34 am (Chile’s time), an earthquake with a magnitude of 8.8 in Ritcher scale occurred in a site very close to Cobquecura, located between Concepción and Constitución (see map below). The plates moved 8 m, and since Ruegg and coworkers calculated a 10 m of slip deficit, either the calculations are overestimated or the earthquake should have been even worse.

Figure 1. Earthquake and areas affected. Notice the location of the epicenter, just as predicted by Ruegg and coworkers.

Nonetheless, the prediction of Ruegg and his team is shocking. They were right about the epicenter and magnitude. The final phrase of the abstract is: “… in a worst case scenario, the area already has a potential for an earthquake of magnitude
as large as 8–8.5, should it happen in the near future”.

Interesting Data

Earthquakes in Chile show a striking regularity: every almost 17 years, a major earthquake (above 8 in Richter scale) occurr. Even more, the majority of the most destructive earthquakes ocurred in the chilean summer:

Figure 2: Major earthquakes in Chile since 1906. The box around 1939 and 1943 shows that the average (1941) was considered to calculate the years between the events (between 1922 and 1941, and between 1941 and 1960). 50% of the events occurred in summer or beginning autumn.

Conclusions

An obvious conclusion for our country, Chile, is the following: scientific observations can assist to make predictions about the most probable sites of a future earthquake, including information about the magnitude. Ideally, a global network across the identified seismic gaps in Chile (one at the north, one near to Valparaiso, one located between Concepción-Constitución and one near to Valdivia, epicenter of the greatest earthquake in the last 200 years) and some other regions , could help to be better prepared for a new earthquake. I don’t know of such an approach is being used in other seismic regions on Earth.

1. Ruegg, J., Rudloff, A., Vigny, C., Madariaga, R., de Chabalier, J., Campos, J., Kausel, E., Barrientos, S., & Dimitrov, D. (2009). Interseismic strain accumulation measured by GPS in the seismic gap between Constitución and Concepción in Chile Physics of the Earth and Planetary Interiors, 175 (1-2), 78-85 DOI: 10.1016/j.pepi.2008.02.015

2. Richard A. Kerr (2010). Did Darwin Help Predict Chilean Quake? Science Now

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8 Responses to “Science predicted the Chile’s Earthquake”


  1. 1 C. Akritidis March 4, 2010 at 3:45 am

    I live in Greece, where earthquakes are quite common. Every time a significant earthquake occurs, someone comes out and says they have ‘predicted it’. Saying that an earthquake of ‘about’ X magnitude will occur ‘around’ region Y ‘within the next’ Z years is utterly useless. With the current accuracy and precision of the prediction, our only option is to be prepared for whatever may come (reinforced buildings, educated public etc.). But no one (except maybe the Japanese) will spend the money to prepare buildings for an 8.8 earthquake. They are not frequent enough to warrant the enormous costs.

    It’s a good thing that seismologists keep working on predictions, but we have a very long way to go and I have a hunch that useful predictions will not become possible until we can monitor tectonic plate movements in real time and in much greater detail that we can today (maybe via a vast surface sensor network or radio satellites).

  2. 2 pabloastudillo March 4, 2010 at 7:54 am

    Well, the apporach used here with GPS was very precise. Since we have in Chile a major earthquake (above 8) every almost 15 years, it seems reasonable to spend wharever it takes to build structures that can resist such magnitudes (Chile has the sad record of having the most powerful earthquakes of all times). Otherwise, we will have to reconstruct the country every 15 years, and that is more expensive.
    The problem with this earthquake is that affected the main part of Chile. So, the economic costs are huge. Chile is celebrating 200 years of independece, and one of the goals of the country was to defeat poverty. But in one night, we have 2.000.000 of affected people without house and belongings.
    At the end, predictions like the preented by Ruegg and his team are very useful to test the emergency protocols, to prepare food and water in special areas, to make trials, etc.

  3. 3 pabloastudillo March 4, 2010 at 7:55 am

    Sorry, it appears a buddy icon in my answer. It should say “…(above eight every almost 15 years)…”

  4. 4 Alejandro March 4, 2010 at 10:25 am

    Teachers always say to students “nature is unpredictable; you can’t know where an earthquake will occur”.

    I think we are capable of saying “where” a quake can
    take place. The problem is the “when”.

    Just as C. Akritidis mentioned, “Saying that an earthquake of ‘about’ X magnitude will occur ‘around’ region Y ‘within the next’ Z years”, is of limited use. The way I see it, the usefulness of these studies rely on letting people know that they should be prepared, that construction codes should change, etc.

    Anyway, these studies should continue and funding to those areas of research is of importance.

  5. 5 Karl Haro von Mogel March 4, 2010 at 3:28 pm

    I interviewed some geologists that were involved in earthquake forecasting, and they made an important distinction between a ‘prediction’ and a ‘forecast’. The former involves a certainty of time and place, however, a forecast involves a likelihood of the time and place. It sounds like they were forecasting, not predicting.

  6. 6 pabloastudillo March 4, 2010 at 4:04 pm

    In this case, there is a certainty of place (almost exactly). About the time, the authors referred to a “near future” when they submitted the article, in 2007. 2010 seems a very near future to me.

  7. 7 juanu March 5, 2010 at 3:41 pm

    Well, if you think about the near future, that does not mean the same thing in geology. A geological event that occurred 1000 years ago, is a recent event in geology. Is similar when you think about biological evolution.

    And I agree that there is an important difference between prediction and forecast. For example, there are forecast of earthquakes here in California, due to the presence of the San Andreas fault, but that does not mean that we know when the earthquake will happen.

  8. 8 pabloastudillo March 5, 2010 at 7:03 pm

    Again.. one thing is to say “it is highly probable that an earthquake happen in the south of Chile”, and something different is to say, for example, “we expect an earthquake between 8-8.5 in the area between Constitución and Concepción”. Besides, in strict terms, when you talk about seismic events, 100 years is a far future, since the scientists expect seismic events in the range of some years. The authors claim that 170 years without an earthquake is a highly unusual time lapse, considering that a major event strikes Chile every 20 years or so.
    Also, some geologists are “predicting” a major seismic event in the Concepción-Constitución area almost 10 years ago.
    Finally, what I want to say here is: “Hey, we should listen to scientists, they have confident information, and we should test our emergency protocols and communication systems, specially in those areas that have a high probability of a major seismic event”.


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