10 BIGGEST MYTHS ABOUT EARTHQUAKES
Unlike other natural disasters—volcanic eruptions, tornadoes, and hurricanes—earthquakes seem to occur without warning, a fact that makes them especially terrifying. Consequently, folklore has arisen that asserts there are signs that indicate when a quake is imminent—though such signs are not supported by scientific evidence. Moreover, there continues to be grave misunderstandings as to what to do during and immediately after an earthquake.
Below is a list to correct these misconceptions. Read on. One or more may save your life.
1. Animals can sense an earthquake before it strikes.
Though there is an abundance of anecdotal evidence of unusual animal behavior before earthquakes, such evidence is usually contradictory. For example, many people have reported that their dog, cat, fish, bird or other pet became nervous and skittish just before an earthquake. An equal number of people have reported their pets became docile and listless just before earthquakes. In my case, I have a cat that has a typical feline temperament: She does a half-dozen unusual things everyday. In short, there is no scientific evidence that animals can sense earthquakes before they happen.
2. Earthquakes occur mostly during hot and dry weather.
This idea dates back to the ancient Greeks who thought earthquakes were caused by air trapped underground and blowing through large caverns. There is no correlation between weather conditions and earthquakes. Quakes are as likely to happen during hot and dry weather as during hot and humid, or cold and wet.
3. Destructive earthquakes occur predominantly during the early morning, especially, just before dawn. They are also more likely during a full moon.
Proponents of the first idea point out that the ground is coldest just before sunrise, which is the time when the ground has contracted the most—making it the most likely time for an earthquake. There is no correlation between the timing of earthquakes and the time of day.
Likewise, there is no correlation between earthquakes and lunar phases. To emphasize this point, the tidal stress during full moon is the same as during new moon. And, yet, few people have ever proposed a correlation between new moon and earthquakes.
4. Many small earthquakes keep big ones from happening.
The magnitude scale of earthquakes is logarithmic, which means a magnitude increase of one (say, from 4 to 5) corresponds to an increase in ground motion of ten times! Moreover, an increase of one magnitude represents 30 times more energy release. And so, there would have to be 30,000 earthquakes similar to the one that struck near Los Angeles on March 28, 2014, to equal one major earthquake on the San Andreas fault. But there are not nearly so many small earthquakes—which is why big earthquakes are inevitable in California. It is the few big earthquakes that release most of the seismic energy that builds between tectonic plates.
5. The ground can open up during an earthquake and swallow people.
This is a frequent image in movies and books, but that is not how earthquakes work. Earthquakes are caused by large masses of rock sliding against each other, not by forming wide gaps where people and other things can fall into.
6. California could fall into the sea because of an earthquake.
California is not destined to fall into the sea. Instead, much of the western United States is being torn slowly apart so that, millions of years in future, what is California today will be a collection of islands being rafted across the north Pacific Ocean.
7. If I live on the east coast, I do not have to worry about earthquakes.
Wrong!!! Though earthquakes are more frequent on the west coast than the east coast, there is still a seismic risk on the east coast. A 7.3-magnitude earthquake devastated Charleston, South Carolina in 1886. An earthquake that originated beneath New York harbor in 1884 caused damage from Hartford, Connecticut, to West Chester, Pennsylvania. An earthquake in 2002 in upstate New York damaged roads, bridges, chimneys and water lines; it was equal in magnitude to the one that occurred south of Los Angeles on March 28, 2014.
8. If inside a building during an earthquake, the safest place to be is in a doorway.
That’s only true if you are in an unreinforced adobe building. In modern structures, the doorway is no stronger than the rest of the building. And so, if shaking starts: (1) Stop what you are doing. (2) Take cover. (3) And hold on.
9. Earthquakes are becoming more frequent.
Worldwide the number of earthquakes remains constant. But, locally, it can vary considerably. Some areas can be seismically quiet for centuries, then spring into life, such as, along the eastern edge of the Indian Ocean at Sumatra where a series of major earthquakes started in 2001, including the magnitude-9.1 event that produced a tsunami. There is a concern that the Cascadia seismic zone off the coast of Washington, Oregon and northern California might do the same.
10. Once the shaking has stopped, it is safe to move around.
No. The 1971 San Fernando earthquake north of Los Angeles that caused the collapse of a hospital consisted of six distinct shocks over a period of ten minutes. The 1906 San Francisco earthquake began with 20 seconds of strong shaking followed by 20 seconds of calm, then a big wham that lasted 40 seconds that some people described as “a freight train slamming into a building.”
And so be forewarned. If an earthquake has just happened, the chance of another one of equal or greater magnitude within the next few days is greatly increased. Plan ahead and be prepared. You can cope with earthquakes.