Earthquakes are measured using seismographs, which monitor the seismic waves that travel through the Earth after an earthquake occurs. Scientists used the Richter scale for many years, but now largely follow the Mercalli Seismic Scale, which the US Geological Survey says is a more precise measurement.
The Richter scale measures magnitude, while the Mercalli Scale measures intensity. Other scales are responsible for categorizing earthquakes using other criteria. The seismic moment magnitude scale measures the area of rock displaced, the stiffness of the rock, and the average distance of displacement.
The advantage of the Seismological Scale of Moment or Mercalli magnitude is that it coincides and continues with the parameters of the Richter seismological scale but corrects the errors due to very high intensities, summarizing the seismic moment in a single number.
The intensity of an earthquake expresses the destructive effects in the place where it is evaluated, the best known scale is the Modified Mercalli Seismological Scalewhich uses Roman numerals to qualify an earthquake based on three criteria:
- How is it perceived by people,
- Due to its effects on buildings and infrastructures,
- Its effects on the ground and the environment.
It is ordered from lowest to highest according to the degree of destruction, ranging from 1 when it is detectable only by very sensitive measuring instruments, to 12 when it is determined as a catastrophe or almost total destruction.
Global monitoring entities such as the US Geological Survey measure these large earthquakes with the modified Mercalli intensity scale. It is because of that Some seismologists, they choose to classify the Richter scale as “obsolete”. (YO)
Source: Eluniverso
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