2010 Earthquakes

The following is a set of questions that I answered by email to Mark Weisenmiller, who contacted me representing "the international Chinese news wire agency Xinhua". The responses are of broader interest.

1) Why does it seem that 2010 has had more recorded eathquakes than in previous years? Is it possible that more earthquakes have happened in more populated areas this year, than in previous years, thus giving the impression that 2010 has had more earthquakes than in previous years?,

According to the US Geological Survey's web site (http://earthquake.usgs.gov/earthquakes/eqarchives/year/graphs.php), the annual average number of earthquakes since 1900 is the following. The numbers in parentheses are the range of values, 1980-2009.

6.0-6.9: 134 (121-178)

7.0-7.9: 15 (5-18)

8.0-9.9: 1 (0-4)

So far in 2010, the same web page gives the following numbers:

6.0-6.9: 143

7.0-7.9: 19

8.0-9.9: 1

Thus so far the year 2010 has been a rather ordinary year in terms of the total number of earthquakes with magnitudes of 6.0 or larger.

So you are correct, that the impression of this being a more active year is caused by the earthquakes that have happened to occur in urban areas - especially the earthquake in Haiti, that struck close to the capital city of a very poorly prepared country. The Haiti earthquake was not a scientific surprise, in the sense that it occurred on a fault system that was known to cause earthquakes of this size and has done so in the past.

2) Does the possibility also exist that since more and more people everyday are online and/or part of a Internet social network (Facebook, Twitter, etc.) that these people are reporting earthquakes to their respective local government or science agencies. Also, how do said agencies verify such claims?,

The earthquakes reported by the USGS are detected and measured by instruments.

The USGS operates a great page for people to report earthquakes that they have felt:

Did You Feel It (http://earthquake.usgs.gov/earthquakes/dyfi/)

Reports from those pages are correlated with measurements of earthquakes.

3) What seems to be, in your professional analysis and estimation, seems to be causing this increase in seismic activity and energy (i.e., hence, earthquakes)? Could it be anything due primarily from human beings or is it completely the actions of plate tectonics?,

Since there is not a significant increase in seismic activity, I disagree with the premise of the question. Whatever it is that is causing you to ask this question is based on inaccurate perceptions.

4) In regards to plate tectonics, do we know yet precisely what causes this action. Is it still believed to be, as had been the case for decades for many scientists and seismologists, convection in the earth's mantle?,

There is no doubt but that plate tectonics is driven by the heat that is inside the earth, which in turn causes some sort of convection in the mantle.

5) Granted, I know that it is very difficult to predict earthquakes but are such massive earthquakes like the kind that shook up the island of Hispanola and virtually destroyed Haiti this past January predictable at all by seismologists?,

No. Also, yes, but that is if you define prediction carefully and in a way that is different from how I think you mean it.

No: There is no reliable way to create a short-term prediction of earthquake (i.e. within the next few days). Many very smart seismologists all over the world are doing their best to find a way, though. By short-term prediction, I mean that the prediction must identify the location, magnitude range, and time interval during which a future earthquake will occur. It is accepted that when we observe an increase in the numbers of small earthquakes in a region, then the probability of a large earthquake is increased, but not to a very high value (e.g. >10%).

If you meant long-term prediction, the story would be a little different. We can measure the accumulation of strain on active faults, or recognize past earthquakes in trenches across the faults, and if the data is sufficient we can determine the average time interval between large earthquakes on those faults. Then we can recognize which faults ought to be getting "close" to rupture. Expressed as probabilistic statement, we might conclude that the probability of a large earthquake on a particular fault is high (e.g. >50%) over a time interval of a few decades.

6) What, to te best of your knowledge, is the casulty and fatality totals due to earquakes in 2010?,

I don't have a handy source of information to answer this question completely. The USGS web site I identified above (http://earthquake.usgs.gov/earthquakes/eqarchives/year/graphs.php) gives statistics of the numbers of deaths since 1980.

7) Is there anything else besides engineers designing earthquake "friendly" buildings that humans can do to protect themselves from earthquakes?,

By "earthquake friendly" buildings, I presume you mean buildings that are strong enough to withstand the shaking of a large nearby earthquake. That is an essential first step. In the United States, our building code has the premise that all structures should protect life safety for levels of shaking that have an annual probability of occurring of 10% in the next 50 years (corresponding roughly to shaking that occurs on average once every 2500 years). Besides that, people can do the following:

a. Protect themselves and their children (Secure or move items that could fall and hurt a person in an earthquake. Protect your valuables, such as your house, by strapping heavy furniture, water heaters, putting precious china inside a cabinet with latches on the doors that will not open in an earthquake, etc. )

b. Prepare to recover (Have food that won't spoil, first aid supplies, water, a little cash, and other items that will help you recover after the earthquake happens.)

c. Prepare to help their neighbors (Because your neighbor may not be as prepared as you are, and helping your neighbor is the right thing to do.)

8) Do you believe that the number of significant earthquakes will increase in 2011 and the upcoming years since, frequently, earthquakes happen at plate boundries and more and more people are living at or near plate boundries? Why or why not?,

I expect that the annual number of earthquakes will go up and down, within or close to the rates given in response to your first question.

I also expect that the number of disasters caused by earthquakes will tend to increase over time because of global population growth, and considering that a significant fraction of that growth takes place in areas that are susceptible to earthquakes.

9) Is it true that some animals can detect earthquakes before they actually occur (I have read articles that state that cows, and especially toads, have this ability)?

It is true that there have been many claims that animals can detect earthquakes before they occur. However, so far as I know, there has never been a rigorous study meeting scientific standards that confirms this belief. My personal opinion is that after people have felt a strong earthquake, if they have noticed any "unusual" animal behavior beforehand they are inclined to report it, but the same "unusual" behavior would be quickly forgotten otherwise.