Earthquakes

5 Pages 1218 Words

Earthquakes


Earthquakes have plagued our lives for as long as people have inhabited the earth. These dangerous acts of the earth have been the cause of many deaths in the past century. So what can be done about these violent eruptions that take place nearly with out warning? Predicting an earthquake until now has almost been technologically impossible. With improvements in technology, lives have been saved and many more will. All that remains is to research what takes place before, during, and after an earthquake. This has been done for years to the point now that a successful earthquake prediction was made and was accurate. This paper will discuss a little about earthquakes in general and then about how predictions are made. Earthquake, “vibrations produced in the earth's crust when rocks in which elastic strain has been building up suddenly rupture, and then rebound.”(Associated Press 1993) The vibrations can range from barely noticeable to catastrophically destructive. Six kinds of shock waves are generated in the process. Two are classified as body waves-that is, they travel through the earth's interior-and the other four are surface waves. The waves are further differentiated by the kinds of motions they impart to rock particles. Primary or compressional waves (P waves) send particles oscillating back and forth in the same direction as the waves are traveling, whereas secondary or transverse shear waves (S waves) impart vibrations perpendicular to their direction of travel. P waves always travel at higher velocities than S waves, so whenever an earthquake occurs, P waves are the first to arrive and to be recorded at geophysical research stations worldwide.(Associated Press 1993) Earthquake waves were observed in this and other ways for centuries, but more scientific theories as to the causes of quakes were not proposed until modern times. One such concept was advanced in 1859 by the Irish engineer Rob...