Earthquakes are a fact of life. The solid rock beneath our feet is not as solid as we like to think. Colossal jigsaw puzzle pieces of the Earth's crust continually reorganize themselves by moving around. The floor of the sea is alive with tremors. Each year one million earthquakes take place.On average, one earthquake hits somewhere every thirty seconds. Most do not do any damage, but some do. One quake in China killed three quarters of a million people.
The odds of you dying in a quake is 1 out of 8,000. Living in Mississippi valley near St. Louis Missouri, the chances are higher. Quakes are rarely felt, but that doesn't mean that it is safe. They are a short distance from New Madrid, Missouri.
We should regard earthquakes not as a sudden abnormal happening but as an effort of the earth to return to normal after it has been slowly strained over a long period of time. Geological faults can be the result of compression of tension or of shearing forces. The magnitude of an earthquake describes the total energy of the shock. Large magnitude earthquakes are usually above 5 on the Richter Scale, but whether they do damage depends on how close people are living to it, as well as the quality of construction in the area.
Volcanoes are a prime cause of large earthquakes, and some suspect that the gravity differences associated with high mountain ranges can also be triggers for them. Ordinary earthquakes are connected with the broad deformation of the Earth's surface, which creates valleys, mid-oceanic ridges, and ocean trenches.
Nowadays, shallow earthquakes are regarded as almost all having the same cause. These ground tremors ultimately stem from the large-scale deformation or the outer part of the Earth resulting from deep-seated global forces, called tectonic forces. The more immediate cause of the shaking we feel during an earthquake is the sudden slip of one plate of Earth against another, which sets up vibrations that radiate outward from the slipping point.
About the Authors
Carolina Toledo & Briseida Lemus are students at West High School in Torrance Unified School District in Mr. Abouaf's first period Integrated Science class.