EARTHQUAKE PREDICTION

Earthquake Prediction

Earthquake Prediction

Earthquakes

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. The moment magnitude (or the related and mostly obsolete Richter magnitude) of an earthquake is conventionally reported, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale.

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacing the ground. When a large earthquake epicenter is located offshore, the seabed sometimes suffers sufficient displacement to cause a tsunami. The shaking in earthquakes can also trigger landslides and occasionally volcanic activity.

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 Robert Mallet. Perhaps drawing on his knowledge of the strength and behavior of

construction materials subjected to strain, Mallet proposed that earthquakes occurred “either by sudden flexure and constraint of the elastic materials forming a portion of the earth's crust or by their giving way and becoming fractured.”(Butler 1995)

Later, in the 1870s, the English geologist John Milne devised a

forerunner of today's earthquake-recording device, or seismograph. A simple pendulum and needle suspended above a ...