Earthquakes & Short Memories

March 13, 2011

Panda’s Thumb has posted an excellent explanation of the Japan earthquake and tsunami by Donald Prothero of Occidental College. Prothero is a geologist with training in seismology. He specifically addresses the issue I mentioned yesterday of earthquake frequency:

Are we seeing more big quakes than normal? This is another question buzzing over the Internet and the media. With our short attention spans, it sure seems like the events in Japan, Haiti, New Zealand and Chile add up to a lot more than average. However, if you do the statistics carefully, the quakes of this past few years are about normal for a given period of time. In any given year, we average about three huge quakes worldwide that are bigger than Mw 6.0 or greater, and thousands of smaller ones; earthquakes are happening every second somewhere around the world. And if we look over enough decades, we see that this current crop of big events is not even the biggest in the past 50 years. The 1960s, with the biggest earthquake on record (1960 Chile) and the second biggest (1964 Alaska), had far more giant quakes than we have had in the past decade.

The myth probably arises because we have short memory spans, and most of us were not even born then, let alone adults paying attention the news in 1960 or 1964. In addition, we now have worldwide instant media coverage of a big quake, especially those in countries like Japan where there are cameras everywhere. By contrast, there was almost no film coverage of the 1960 disaster in southern Chile, and only a few films were made of the 1964 Alaska quake. Most people learned of those quakes by the newspaper days later, and saw little or no film footage on TV.

I guess there’s no need to ratchet up the Rapture Alert Level just yet.

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