ANATOMY OF AN EARTHQUAKE

Magnitude and Intensity

The severity of an earthquake may be measured by its magnitude or its intensity. Charles Richter developed a scale in the 1930's for measuring the magnitude of earthquakes. As the number of seismograph stations grew, new scales based on Richter's idea were developed. What is called the moment magnitude scale, for example, measures the energy released at the source of the quake.

Of course, these scales do not always reveal the damage inflicted by an earthquake.  Consider an earthquake in northern Bolivia in June 1994, with a magnitude of 8.2, which reportedly killed only five people. Yet, the 1976 quake in Tangshan China-with the smaller 8.0 magnitude-resulted in hundreds of thousands of deaths! 

In contrast with magnitude, intensity registration shows the effects that an earthquake has upon people, structures, and the environment.  This is a more descriptive  measure of the severity of an earthquake in human terms. After all, tremors  in themselves do not usually harm people.  Instead,  collapsing walls, rupturing gas or power lines, falling objects and the like cause the most injuries and fatalities.

One goal of seismologists is to be able to provide early warnings of earthquake activity.  A digital program called the Advanced Seismic Research and Monitoring System is being developed. According to a CNN report, this system-coupled with speedier access and more high-powered software applications-will help officials to "be able to almost instantly pinpoint areas where the most violent shaking from an earthquake has occurred."  This, in turn, will make it easier for authorities to send help into affected areas. 

Obviously, being prepared for an earthquake can reduce injuries, minimize property damage and - most important -save lives. Yet, earthquakes continue to occur. So the question arises: How have people been helped to cope with the aftermath? 

Next time: COPING WITH THE AFTERMATH

From the Awake! magazine