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EARTHQUAKE SEASON: EXPLANATION OF A COMMON MYTH By S. Danielle Hanson with Evelyn Kruis Severe weather has had devastating effects on civilizations, from the ancients to the present, leaving people fearful of the next event. Perhaps one of the most unsettling aspects of one of these events is their unpredictability. As history has unfolded, there have been many advances in the understanding of weather. For example, weather patterns are now being observed as cyclical and even predictable within a given geographic location. Earthquakes come out top of the list as one of the most volatile phenomena. There have been several attempts to predict earthquakes in a manner similar to that of predicting the weather. Aristotle, in a text on earthquake theory, presents a hypothesis on weather that has been accepted famously for centuries: “We must suppose the action of the wind in the earth to be analogous to the tremors and throbbing caused in us by the force of the wind contained in our bodies. Again, we must think of an earthquake as something like the tremor that often runs through the body after passing water as the wind returns inwards from without in one volume. “ -Aristotle Aristotle thought the earth was like a sponge and that the wind dove into cavernous areas below the surface. During the windiest seasons, harder wind meant more air was being forced into the earth. Aristotle reasoned that the process was like that of air within the human body, more air produced a larger internal tremor. Accordingly, the presence of more wind on the surface indicated that there would eventually be more of an underground disturbance, resulting in an earthquake. As a result, windy seasons became known as earthquake season. Anaximense of Miletus, added to Aristotle’s hypothesis by explaining that what the wind does to the earth can also be done by either a dry or wet season, “the earth grows dry in time of drought and breaks up, whereas the rain makes it sodden and destroys its cohesion.” Accordingly, wind, drought, or rain can cause underground disturbances, resulting in an earthquake. S. Danielle Hanson in her lab in Los Angeles Both these theories have since been disproved. Today, we know that the Earth’s outermost layer, the crust, moves due to tectonic forces – generally from the convection of the denser mantle below. This rigid and fractured crust is broken into large sections called tectonic plates, which are typically 20-30 miles thick. The boundary at which the plates move past one another is called a fault zone. Massive amounts of friction (stickiness) cause the plates to become stuck and then generate lots of strain. When the friction releases, the moving plates rebound, quickly sliding past one another. At that moment, a huge amount of energy is released in the form of an earthquake. Thus Earthquakes have to do with tectonic forces from deep within the solid, plastic (moveable) earth, not weather. Weather does not cause or signify impending earthquakes. Do not be fooled into thinking you can watch the weather to predict earthquakes. Take the time now to learn what you can do to be safe in the event of an earthquake in your area. After all, disasters happen when proper preparation does not. For starters, log onto www.youngmeteorologist.org and PLAY THE WEATHER GAME! Let Owlie Skywarn and his friends will lead you through five severe weather challenges. Together you’ll work to earn your Young Meteorologist Certificate! Owlie Skywarn was revitalized by Plan!t Now, an NGO that assists by educating communities at risk of being negatively impacted by severe weather events including hurricanes and tropical storms, flooding, winter storms, earthquakes, fires and man-made disasters about severe weather science as it pertains to preparedness. Working with public, government, nonprofit and private partner, we promulgate important information that helps those at risk prepare their families and communities. For more information visit: http://www.planitnow.org/.