The Earth is Shaking!
Earthquakes are formidable. Did you ever hear of the infamous 1906 earthquake that destroyed San Francisco or one the that took place in the movie Earthquake '77? Earthquakes can destroy entire cities yet they have created the world we live in today. Without the continental shift, or the moving of the tectonic plates, we wouldn't have great places to bungee jump like the Grand Canyon, cool places to ski like the Rocky Mountains, or have
volcanoes like the world's most active one, Kilauea on Hawaii.
On average, an estimated 18 major and two million minor earthquakes happen every year. At this rate, that means more than 8,000 earthquakes a day. Maybe that rumble you felt wasn't Godzilla! Even though earthquakes happen regularly, most people are baffled by them and scared of them; they would rather be pitted against a raptor from "Jurassic Park" than be forced to experience an earthquake.
To simplify the whole "quaking" process, an earthquake is somewhat like riding the bumper cars. In the same way that you constantly bump against your friend's car, earthquakes are caused when plates in the earth's surface, called tectonic plates, bump and grind against each other. In 1920, a German geologist named Alfred Wegener realized that the world had been one large land mass, or supercontinent, and that slowly, pieces of this land mass had drifted apart to create the world we live in now with seven continents.
This process of separation, called the continental drift, is caused by the constant motion of the lithosphere over a softer layer called the asthenosphere, which also is constantly shifting. The lithosphere is the hard outer layer of the earth which is divided up into seven major plates and many smaller ones. These seven major plates include the following: Eurasion plate (which is covers Asia and Europe); North American plate (North America); South American plate (South America); Pacific Plate; African plate (Africa and Middle East); Australian plate; and the Anartic plate. For the most part, each major plate represents one of the seven continents. There are many smaller plates like the Caribbean plate, the Philippine plate, the Cocos plate and many others.
Let's go back to the bumper cars analogy. The slick surface of the bumper car rink would be the asthenosphere and the cars themselves would represent the different plates. Of course, the cars can't move on their own; the cars slide along the rink's surface with the help of electricity. Although we do not know for certain, scientists believe that the earth's plates move because of the transfer of heat energy, or convection, occurring in the center of the earth. In other words, much like the electricity, heat moves up from the core of the earth, heating and causing the asthenosphere to move and shift the tectonic plates. Because the plates are all connected along the edges, the motion causes them to bump and grind against each other like Puffy Combs and Lil' Kim doing the wild thing, or you driving your bumper car uncontrollably and bumping into your friend's! Eventually, after millions of years of the earth's core losing heat, the plates will stop moving and stabilize.
When the earth's plates shift against each other, they break off into smaller pieces and create faults. As these new plates and faults are formed, ocean ridges, undersea mountain ranges and volcanoes are formed as well. Volcanoes, for example, are found along mid-ocean ridges and at isolated hot spots on the earth's plates called magma regions. Similar to an earthquake, the formation of a volcano begins well below the lithosphere at the earth's hot core.
At these "hot" spots, the heat of the earth's core sucks the earth's surface deep into the magma region and creating a funnel-like hole. Think of a toilet bowl before you flush. The water in the bowl is resting calmly until you flush and the water is sucked into the sewer system in a vacuum like motion. Now, the earth's core is the person flushing and, whoosh, sucks the plates into its center. The funnel-like hole created is the center of the volcano where hot lava can rush out.
The height of the volcano, or any mountain, is determined by the "strike-slip" shift. A "strike-slip" shift is caused when two plates hit each other so hard, that one is forced on top of the other. It's like playing with matchbox cars: when you slam them into each other, one has to fly up and do an incredible flip over the other. In this same way, one plate stacks on top of the other. After the suction of the plates occurs, the earth's rock cools and forms a mountain. The Rocky Mountains in the United States were created with the "strike-slip" shift.
Links to Other Dispatches
Becky - Gators and brown goo can't keep the Trekkers from the swamps of the south
Daphne - Death Valley sans air conditioning and big hair in Las Vegas
Neda - Twisters, cyclones, and tornadoes, oh my! Chasing wacky weather in Toto-land
Stephanie - The future looks brighter for the
proud Navajo and Shoshone nations
Nick - Searching for a hint of nature at the "Bridge of God"
Teddy - Plumbing the depths of Yellowstone Park
Team - Pangaea? Isn't that some kind of weird pasta?