The magnitude of an earthquake is calculated by using the Richter scale formula, which is mentioned and explained in brief, in the following article.
We are all aware of the disastrous consequences of an earthquake. Whether mild or major, they always leave behind some damage in their wake. The only difference is that the damage is lesser when it’s mild, and more when it’s a major one. Whenever we hear of an earthquake, its magnitude is always explained in terms of the Richter scale. For instance, the one that hit Haiti in 2010, measured 7.0 on this scale. This figure is calculated on the basis of the tremors caused at that time, as well as the energy that was released by the tremors. All this is calculated with the help of a formula, as explained below.
Richter Scale Explained
The Richter scale was created by Charles Richter, who initially developed a scale simply to measure the earthquakes that had occurred in California. He collected all the data that had been recorded from Caltech’s Seismological Laboratory, where he intended to quantify the strength of tremors that were caused due to earthquakes. He tried to create a measure of an earthquake based on its magnitude at the epicenter, as well as the amount of energy released at the time of the tremors. His data consisted of the ones in California that occurred back then, which were measured with a seismograph. This was done when the seismograph made waves on a paper, to record the tremors. The distance between every wave that was created on the paper, was considered to be the distance of the tremor to the epicenter. As he continued to study this data, he tabulated it in the form of minor to major earthquakes. This tabular data, then became the basis of the Richter scale. Initially, it was used only as a relevant measure of earthquakes in California. However, it soon became a standardized measure worldwide.
The Richter scale formula measures and records the movement of the Earth at the epicenter of an earthquake. This number is then used to calculate the energy that has been released. This formula was developed by Charles Richter, in the year 1935. It was prepared from the logarithm of amplitude of waves, that were recorded by seismographs. The two ways in which an earthquake is measured on this scale, are based on the ground movement caused by the earthquake, which is measured by a seismometer, and the energy released by the earthquake, which is correlated with the ground movement. The formula is:
ML = log10A – log10A0(δ)
Here A is the greatest deviation on the Wood-Anderson seismograph, while A0 depends on the distance of the location from the epicenter, δ. Since this is a logarithmic formula, each number that represents the magnitude of an earthquake, increases tenfold in measured amplitude, with an increase in the whole number. For instance, an earthquake measuring 7.0, is 10 times more powerful than one measuring 6.0. Moreover, the energy released by each earthquake, measuring differently, increases 31.6 times the amount of energy released, per measure, while each increase of 0.2, results in doubling the energy released.
The range of the Richter scale is between 0 and 10. However, an earthquake can measure above 10.0, which is then called an epic earthquake. Given below is a table, that helps you understand the magnitude of an earthquake, and the kind of damage it can cause to life and property.
|0 – 2.0
|2.0 – 2.9
|Experienced, but not recorded.
|3.0 – 3.9
|Experienced, but no damage caused.
|4.0 – 4.9
|Shaking and rattling of items experienced, but no significant damage caused.
|5.0 – 5.9
|Affects weak constructions, and causes mild damage to stronger constructions.
|6.0 – 6.9
|Affects areas up to 160 km from the epicenter, in populated areas.
|7.0 – 7.9
|Can spread to further areas and cause severe damage.
|8.0 – 8.9
|Can go beyond a hundred miles and cause severe damage.
|9.0 – 9.9
|Can go beyond a thousand miles with disastrous effects.
|Never been recorded.
The Richter scale formula has helped us understand the magnitude and the effects on an earthquake in a very simple manner. Though no earthquake can be prevented, certain safety tips can definitely be followed to minimize the subsequent damage to life and property.