The Richter Scale and the 1964 Alaska earthquake

Earthquakes

Charles Richter determined that the seismic waves emitted from an earthquake could be used to estimate its magnitude, and he developed a calibrated system for measuring these waves commonly known as the Richter Scale (Earthquakes). The Richter Scale formula is based on the discovery that the larger the earthquake, the larger the amplitude of ground motion at a given distance from the quake. The Richter Scale equation is:

R (x) =.67 • log (.37x) + 1.46

R (x) equals the magnitude of that earthquake on the Richter scale and x equals the energy of an earthquake in kilowatt-hours (Earthquakes). The small numeric differences in values of R (x) can be misleading if one does not understand that the scale is logarithmic, which means that each whole number of the scale actually increases by 10. Thus, a magnitude 7.0 earthquake is ten times stronger than a 6.0; a 7.0 is 100 times greater than a 5.0; and a 7.0 is 1000 times greater than a 4.0.

In the United States, California receives the most attention for earthquakes, but Alaska actually has had eight of the largest ten earthquakes in this country. The largest was a magnitude of 9.2 at Prince William Sound Alaska on March 27, 1964 (The largest earthquakes in the United States). This earthquake triggered a Pacific-wide tsunami. The earthquake and resulting tsunami took the lives of 115 people (Earthquake facts and follies).