Common Myths about Earthquakes
Can animals predict earthquakes?
So far, scientists have been unable to find consistent and reliable animal behavior patterns before earthquakes. Scientists have also had trouble finding any sort of "signals" that animals might detect to alert them — if they had, you can bet that scientists would be vigilantly detecting those signals, too! Most, but not all, scientists pursuing this mystery are in China or Japan.
The earliest reference we have to unusual animal behavior prior to a significant earthquake is from Greece in 373 BC. Rats, weasels, snakes, and centipedes reportedly left their homes and headed for safety several days before a destructive earthquake. Anecdotes abound of animals, fish, birds, reptiles, and insects exhibiting strange behavior anywhere from weeks to seconds before an earthquake.
Can some people sense that an earthquake is about to happen? Are there "earthquake sensitives"?
There is no scientific explanation for the symptoms some people claim to have preceding an earthquake, and more often than not there is no earthquake following the symptoms.
Is there earthquake weather?
There is no connection between weather and earthquakes. Earthquakes are the result of geologic processes within the earth and can happen in any weather, in all climate zones, and in all seasons of the year. Earthquakes originate miles underground. Wind, precipitation, temperature, and barometric pressure changes affect only the surface and shallow subsurface of the Earth. Earthquakes are focused at depths well out of the reach of weather, and the forces that cause earthquakes are much larger than the weather forces.
In the 4th Century B.C., Aristotle proposed that earthquakes were caused by winds trapped in subterranean caves. Small tremors were thought to have been caused by air pushing on the cavern roofs, and large ones by the air breaking the surface. This theory lead to a belief in earthquake weather, that because a large amount of air was trapped underground, the weather would be hot and calm before an earthquake. A later theory stated that earthquakes occurred in calm, cloudy conditions, and were usually preceded by strong winds, fireballs, and meteors.
Sometimes, we are asked: "Do earthquakes change the weather in any way?" Earthquakes themselves do not cause weather to change. Earthquakes, however, are a part of global tectonics, a process that often changes the elevation and shape of the terrain. Tectonics can cause inland areas to become coastal or vice versa, or raise new mountain ranges, and this affects weather. Changes significant enough to alter the climate occur over millions of years.
Are there more earthquakes in the morning/in the evening/at a certain time of the month?
Earthquakes are equally likely to occur at any time of the day, month or year. The factors that vary between the time of the day, month, or year do not affect the forces in the earth that cause earthquakes.
Can the ground open up during an earthquake?
Shallow crevasses can form during earthquake-induced landslides, lateral spreads, or other types of ground failures. Faults, however, do not open up during an earthquake. The two faces of a fault move along each other, not away from each other, and it is the locking together and releasing of the two fault faces that causes earthquakes. If faults opened up, no earthquakes would occur because there would be no friction to lock the two faces of the fault together.
Will California eventually fall into the ocean?
No. The San Andreas Fault System, which crosses California from the Salton Sea in the south to Cape Mendocino in the north, is the boundary between two tectonic plates — the Pacific Plate and North American Plate. The Pacific Plate is moving northwest with respect to the North American Plate at approximately 46 millimeters per year (about the rate your fingernails grow). The strike-slip earthquakes on the San Andreas Fault are a result of this plate motion. The plates are moving horizontally past one another, so California is not going to fall into the ocean. However, in about 12 million years, Los Angeles and San Francisco will be adjacent to one another!
Do earthquakes cause volcanoes?
No, there are different earth processes responsible for volcanoes. Earthquakes may occur in an area before, during, and after a volcanic eruption, but they are the result of the active forces connected with the eruption, and not the cause of volcanic activity.
Can you prevent large earthquakes by making lots of small ones, or by "lubricating" the fault with water or another material?
Seismologists have observed that for every magnitude 6 earthquake there are 10 of magnitude 5, 100 of magnitude 4, 1,000 of magnitude 3, and so forth as the events get smaller and smaller. This sounds like a lot of small earthquakes, but there are never enough small ones to eliminate the occasional large event. It would take 32 magnitude 5's, 1000 magnitude 4's, or 32,000 magnitude 3's to equal the energy of one magnitude 6 event. So, even though there are many more small events than large ones, there are never enough to eliminate the need for the occasional large earthquake.
As for "lubricating" faults with water or some other substance, injecting high pressure fluids deep into the ground is known to be able to trigger earthquakes to occur sooner than would have been the case without the injection. However, this would be a dangerous pursuit in any populated area, as one might trigger a damaging earthquake.
What is the "Triangle of Life" and is it legitimate?
The "Triangle of Life" refers to a claim that the safest place to be if you are indoors during an earthquake is flat on the floor next to a large object that cannot collapse, like a couch or bed. The claim is that, if the ceiling collapses, a person can avoid being crushed if they are in the space under a piece of the ceiling that falls to rest leaning against the non-collapsible object.
However, in the United States and other regions with modern building codes, buildings are constructed to prevent "pancaking" (having an upper floor collapse onto a lower floor) in this way. Extensive research has indicated that the American Red Cross' recommended method of "Drop, Cover, and Hold On" has saved lives in the United States. The observations that led to the "Triangle of Life" claim were made largely in regions with poorer building codes.
So, "Drop, Cover, and Hold On" is the more proven safety method for buildings constructed to modern building codes. However, for very poorly constructed buildings, the "Triangle of Life" may have some merit.
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