Have you ever wondered how an earthquake occurs? We will explain it to you in detail.
Earthquake, tremor or earthquake are the various ways of calling the movements of the plates of the Earth’s crust. Certainly earthquake is the term most used for telluric movements and earthquake is usually used for a very intense earthquake.
Rolling Hills in the Palouse region of the northwestern United States, KARI/ESA
Currently, thanks to seismology, a branch of geophysics, we know in more detail the seismic activity and the constitution of the interior of our planet. But before understanding how earthquakes occur, we must understand how our planet is formed.
Layers of the Earth
The Earth is made up of different layers from its interior, it could be said that it is a mass of hot metal covered by cold metal and earth. The core is the center of the planet, in this space molten metals are housed that flow like and in fact, are responsible for producing the Earth’s magnetic field.
The mantle is responsible for covering the Earth’s core and finally we have the crust. Each of these layers is in turn subdivided depending on its characteristics. We have, for example, the inner and outer core; and the lower and upper mantle.
The coldest and most solid surface of the mantle (upper mantle) is divided into what we know as tectonic plates. It is known that there are 15 of them of large size and at least 40 microplates. At the edges of each of the plates, a large amount of energy is concentrated that at some point must be released and is precisely released as an earthquake.
In other words, earthquakes originate as a consequence of the sudden release of energy from within the Earth. The movements propagate in all directions in the form of waves and are reflected on the Earth’s surface, this is how an earthquake occurs.
How does an earthquake occur? Most frequent causes
The Mexican Geological Service explains that seismic movements are of short duration, of variable intensity and regularly produced by the displacement of tectonic plates. Despite this, they can also have several different causes:
- Tectonics: They originate from the displacement or sudden breakup of the technical plates that make up the Earth’s upper mantle. It is the most common cause behind tremors.
- Volcanic: It is very rare, however, it originates when the eruption is violent and generates large shocks that cause the ground to move. They regularly affect surrounding areas and their field of action is reduced compared to the tectonic origin.
- Sinking: It happens when erosive action of subsoil waters has occurred inside the crust, which causes a kind of cavern or hole that ends up collapsing under the weight of the surface.
- Landslides: The weight of the rocks is of such magnitude that it tends to flatten them and can produce earthquakes by causing landslides along faults. Although they are generally not of great magnitude.
- Atomic explosions: Of anthropogenic origin and are believed to have an influence on the production of earthquakes.
How are earthquakes measured?
The Richter or magnitude scale is the best known and most widely used way to classify and measure earthquakes. Values range from 1 to an open end. The measurement is quantitative and what it measures is the seismic energy released in each telluric movement, that is, the magnitude.
M. Meschede
On the other hand, there is another concept known as intensity, this refers to qualitative measurements. It has to do with the description of the damage that the earthquake causes in terms of human, material and economic losses.
According to the Mexican Geological Service, we can classify the effects of earthquakes according to their magnitude according to the following table.
Richter Scale or Magnitude Effects of the earthquake or earthquake Less than 3.5 It is generally not felt, but it is recorded. 3.5 – 5.4 Often felt and causes only minor damage. 5.5 – 6.0 Causes light damage to buildings. 6.0 -6.9 Can cause severe damage in areas where many people live. 7.0 – 7.9 Major earthquake causing serious damage. 8 or greater Large earthquake, generates total damage to nearby communities.