Earthquake Myths, Part Two


Another earthquake myth is that earthquakes occur more often at one time of year or at a certain time of day.  Not true, they are equally likely to occur at any time.  Weather also does not have any significant effect on earthquakes.

One myth that pops up whenever two or more planets are in alignment is that the increased gravity or tidal pressure will cause earthquakes.  Nope.  The increased gravity is so tiny that it has no effect.  Even if every planet was in perfect alignment with us they would provide less than 2% of the moon’s pull.  And because of the moon’s elliptical orbit, its distance varies by as much as 40,000 km every month.  So every two weeks “we see a change in gravitational effects from the Moon more than 10 times greater than all the other planets combined,” according to Phil Plait.  You can check out his excellent explanation here: http://www.badastronomy.com/bad/misc/planets.html

The idea that animals have some advance warning of earthquakes may or may not be true.  There’s been a great deal of anecdotal evidence about animals acting strangely or fleeing the area before a quake. We have a report from Greece in 373 B.C. that rats, weasels, snakes and centipedes fled the area before a big quake. In 2009, a researcher in Italy reported that 100% of toads left the area before an earthquake and they returned afterwards. Anecdotal evidence is suspect, however, and people often forget the many times animals acted oddly and there was not a quake.

One hypothesis is that animals are more sensitive to electrical and magnetic fields or the release of certain gases.  Obviously it is very difficult to do research on this (“What’s that, Lassie? A 7.2 earthquake tomorrow?”)  We need a lot more scientific data, but it’s very interesting to me because if we could prove that some animals can sense earthquakes before they happen, then we could try to find out they do it.  That might give us a way to accurately predict earthquakes.  That’s a lot of “ifs,” though.

It is not true that earthquakes will cause California to fall into the ocean, no doubt disappointing conservatives and disaster filmmakers.   The San Andreas fault is where the Pacific plate and the North American plate meet.  The Pacific plate is moving northwest at the rate of two inches per year.  This means that in about 15 million years Los Angeles and San Francisco will be side-by-side.

Another California related myth is that California has more earthquakes than any other state.  Actually, Alaska has the most quakes.  I was surprised to learn that every state in the U.S. has had earthquakes.  According to the U.S. Geological Survey, Florida and North Dakota have the fewest.  Of course, in Florida you have hurricanes and wildfires to worry about and North Dakota has blizzards and floods. 

Finally, the advice to stand under a doorway during an earthquake is outdated information.  It’s also not recommended that you run out-of-doors during a quake, though perhaps it is human nature.  You’re now advised to “drop, cover and hold.”  If inside, stay there and get under a sturdy piece of furniture.  If outside, get into an open area away from buildings and power lines.  If in a tall building, stay away from windows and outside walls and get under a table or desk.

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