Earthquakes

... s phenomena was observed in the big earthquake which struck San Francisco in 1906.

Subsea tremors may result in a tsunami. A tsunami is another name for a tidal wave but because tides have nothing to do with the creation of these waves, the term tsunami is used instead. These waves move with tremendous speed and power and can devastate coastal communities where the sea bottom "lifts" the water as it rolls up on the land.

Measuring the Intensity of Earthquakes

The most well-known method of measuring the intensity of an earthquake is the Richter scale. The Richter scale is named after an American seismologist named Charles Francis Richter, and measures the amount of energy released at the focus of a quake. It uses a logarithmic scale that runs from "1" to "9." Because this scale is logarithmic, each number is actually an increase of ten times than the number which precedes it. Thus, a 7.0 earthquake is ten times more powerful than a 6.0 and 100 times more powerful than a 5.0. To allow a greater degree of precision, a decimal equivalent was provided. At one time it, was believed that an earthquake with a magnitude of 8.5 was the most powerful possible but new seismic measuring techniques have revealed that it is possible to reach 9.5.

Another method of measuring the intensity of earthquakes was developed at the turn of the century by an Italian seismologist by the name of Giuseppe Mercalli. The Mercalli scale measures shaking with gradations from I to XII. Since the effects of the earthquake diminish with the distance it is from the fo ...