Richter Scale Day rumbles in
Do you know which earthquake is listed as the most destructive in South Africa’s history?
TODAY, Wednesday, 26 April is Richter Scale Day, in honour of Charles F Richter’s birthday.
Richter, who was born in 1900, developed the Richter Scale in the 1930s at the California Institute of Technology.
Since then, his system has been the foremost measure of seismic activity.
According to the US Geological Survey (USGS), the Richter Magnitude Scale is “a mathematical device to compare the size of earthquakes. The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs. Adjustments are included for the variation in the distance between the various seismographs and the epicenter of the earthquakes.
On the Richter Scale, magnitude is expressed in whole numbers and decimal fractions. For example, a magnitude 5.3 might be computed for a moderate earthquake, and a strong earthquake might be rated as magnitude 6.3. Because of the logarithmic basis of the scale, each whole number increase in magnitude represents a tenfold increase in measured amplitude; as an estimate of energy, each whole number step in the magnitude scale corresponds to the release of about 31 times more energy than the amount associated with the preceding whole number value.”
The largest recorded earthquake, according to the USGS was in Chile in 1960 with a magnitude of 9.5 on the Richter Scale. This was followed by the 1964 quake in Southern Alaska, measuring 9.2; the one off the coast of Northern Sumatra in 2004 at 9.1; the earthquake near Japan in 2011, also a 9.1 and one off the Russian coast, measuring 9.0.
The 1969 earthquake near Tulbagh, measuring 6.3 is listed as the most destructive in South Africa’s history.
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