Mar. May 30th, 2023
  • This number system helps us understand the magnitude of an earthquake even if we are miles of kilometers away

The earthquake magnitude that shake the planet is measured with the well-known Richter scale. This method, coined in 1935 by seismologists Charles Francis Richter and Beno Gutenberg, was created to distinguish small earthquakes that occur continuously (and almost imperceptibly) in a territory of the highest intensity tremors that have an impact on the terrestrial geography, landscapes and human activities. Thanks to the figures that this escalation reflects, we can understand the magnitude of an earthquake even though we are miles and kilometers away from its epicenter.

The Richter scale is, basically, a tool to reflect the energy released during an earthquake. Its creators were inspired by the logarithm system used in the field of astrophysics to study the brightness of stars. This idea, applied to the field of seismic study, has allowed the creation of a system to analyze the seismograph activity during their continuous monitoring of terrestrial activity. According to this system, the greater the amplitude of the wave captured by a seismogram, the greater the force released by the earthquake and, thus doing, the greater the magnitude assigned to it.

‘Light’ earthquakes

But from what number on the Richter scale can we say that an earthquake has been of great magnitude? Well, it depends. This monitoring system collects earthquakes of all kinds of intensity. The to 2 lower are known as microquakes and they are practically imperceptible to people (in fact, there are about 8,000 a day even if we don’t realize it). The tremors between 2 and 3 (of which there are almost 1,000 daily) also tend to go largely unnoticed by humans. So, from our point of view, earthquakes as such begin to be noticed from magnitude 3.

Every year the world registers nearly 50,000 minor earthquakes (magnitude 4) and some 6,200 light earthquakes (magnitude 5). During these the shaking of objects can be observed but, in general, no damage is usually produced. TO from a magnitude 6, earthquakes can start to cause damage to buildings and infrastructures (although this, of course, depends on their state). On average, it is estimated that the world experiences about 800 episodes of this type per year.

‘Strong’ earthquakes

The tremors considered strong They are those that are above a magnitude 6. It is estimated that around the world there are about 120 annual earthquakes of this type, which can cause damage hundreds of kilometers around. This is the case, for example, of the two earthquakes that occurred this Monday on the border between Turkey and Syria (the first, of magnitude 7.8 and the second of 7.5). According to the first analyzes on the ground, these seismic movements opened a crack in the ground of more than three meters in a strip of more than 150 kilometers long.

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Earthquakes that are reflected with a magnitude greater than 8 are described as «catastrophic» episodes. Of these, between 1 and 3 a year are registered and, due to their violence, they usually cause damage hundreds of kilometers around. The tremors with a magnitude greater than 9 They stand out among the most serious ever described. It is estimated that only one or two of these are recorded every 20 years.

He last earthquake of this magnitude It took place on March 11, 2011 in Japan, when a magnitude 9 earthquake triggered a violent tremor and a powerful tsunami. The same thing happened on December 26, 2004 in Indonesia, when a magnitude 9.1 tremor struck. He most violent earthquake ever observed It took place on May 22, 1960 in the Chilean town of Valdivia. The tremor reached a magnitude of 9.5, causing more than 1,600 deaths and 3,000 injuries and displacing more than two million citizens.

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