March 2, 2010
Many kids (adults, too) are asking what is happening inside the earth, with January’s devastating earthquake in Haiti followed so quickly by a near record-breaking quake in Chile over the weekend.
In fact, the two earthquakes happening within a few weeks of each other are a coincidence. Each quake was independent and happened along different fault lines and for a different reason. There should be no particular reason for another earthquake to happen now along a different fault line. That’s not to say that there won’t be many aftershocks along the same fault lines that the Haiti and Chile earthquake happened. There will be many of those. But there is no particular "earthquake time" happening now. Every moment of the year, someplace on Earth the ground is shaking and we call that an earthquake.
My family sometimes jokes with me that whenever anything happens, I pipe up and say "I’ve written a book about that." At this point in my writing career, it’s nearly true!
Here are some relevant words and definitions from my EARTHQUAKES book.
FAULT: A crack or break in the earth’s crust. A fault is caused by movement of the rock formations that make up the crust. The San Andreas fault in California stretches for one thousand miles from Mendocino to the Gulf of California. Earthquakes often occur along faults. [Fault comes from a Latin word meaning "to fail."]
FOCUS: The origin of earthquake waves, or the location inside the earth where rocks shifted during an earthquake. From this point the energy of an earthquake speeds outward through the surrounding rocks in all directions. [Focus is the Latin word for "hearth", the center of the ancient Roman household.]
STRESS: The application of forces, such as tension, that tend to cause an object to change its shape or size. Stress is expressed in force per unit of area, such as pounds per square inch or grams per square centimeter.
SEISMIC: Having to do with earthquakes or other movements of the earth’s crust. Seismic waves are waves of motion in the ground produced by earthquakes. [Seismic comes from a Greek word meaning "to shake."]
SEISMOLOGY: The scientific study of earthquakes and other movements of the earth’s crust.
With the earthquakes in Haiti and in Chile in recent weeks, some people are wondering if something special is going on inside our planet Earth. Is there a reason for all the earthquakes in the news at the same time? Probably not. The earthquakes in Haiti and Chile are on different faults and of different kinds. Both are huge quakes and the results have been terrible. But each happened independently and they are related to each other only in the sense that they both demonstrate the enormous forces within our planet.
Posted by: Seymour Simon
