The Symlar San Fernando Valley Earthquake of 1971 :: Seismology natural disaster

Earthquakes are best described as a shaking or vibration of the ground caused by breaking of rock. Sometimes they are very strong and other times you would hardly notice them. This shaking occurs when stress that builds up in the crust is suddenly released as the crust breaks free and/or slides against the other pieces of crust. Earthquakes may also be thought of as the breaking of a popsicle stick by applying pressure to both ends at the same time. Should you try this experiment , you will feel the pressure build up as you apply more force until the stick snaps. When the stick snaps you will feel an instant of pain at your fingers as the stress reduces and energy waves move throughout the stick. When the earth's crust is placed under similar types of stress, binding as the stress builds, it will also snap and release the energy into the surrounding rocks, 'ooch'. Thinking about earthquakes will become more clear if you try another experiment. Experiment Find two regular red bricks, or any color will do. Place them on the table side-by-side touching each other. Now push them together with a little bit of force and slide one past the other while applying the force. You will find that they do not slide past each other very easily while applying a force to push them together. As you manage to force the bricks past each other, you may notice by feeling and hearing a vibration and a jerking type of movement. You have simulated an earthquake . Now set a small toy , a rubber eraser, a coin or other item on each of the bricks and do the experiment again. You can see that the objects bounce, fall and move about as the bricks slide past each other. Taadaa! You have created an earthquake in the toy world! Now place one of the bricks one on top of the other. Put some toys on top of the upper brick and slide the top brick across the bottom brick. This is called a 'thrust' fault when one piece of crust slides over top of the other. This is much mo re like what happened during the Sylmar earthquake. Are the toys O.K.? Unfortunately, this is what happens in the real world too. Real Life The vibration and jerky movements cause things to fall, bounce around and sometimes break.