How does an earthquake occur? Causes and characteristics

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 that is most used for telluric movements and earthquake is usually used for an earthquake of great intensity.

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 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 that flow like water are housed and, in fact, are responsible for producing the earth’s magnetic field.

The mantle covers the Earth’s core. Y finally we have the crust. Each of these layers in turn is 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 large ones and at least 40 microplates. At the edges of each of the plates, a large amount of energy is concentrated that must be released at some point and is released precisely as an earthquake.

In other words, earthquakes originate as a consequence of the sudden release of energy from the interior of 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 they are of short duration, of variable intensity and are 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 rupture of the technical plates that make up the terrestrial upper mantle. It is the most common cause behind tremors.
  • Volcanic: It is very rare, however, it originates when the eruption of a volcano is violent and generates great shocks that cause the movement of the ground. They regularly affect areas surrounding the volcano and their field of action is reduced compared to the tectonic origin.
  • Sinking: It happens when erosive action of subsoil waters has taken place 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 mountains 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 it is believed that they have an incidence in 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 it is quantitative and what it measures is the seismic energy released in each telluric movementthat is, the magnitude.

    M. Meschede

    On the other hand, there is another concept known as intensity, this refers to qualitative measurements. Is related to 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 or Magnitude scale
    Effects of the earthquake or earthquake

    Less than 3.5 Generally not felt, but registered. 3.5 – 5.4 Often felt and only causes minor damage. 5.5 – 6.0 Inflicts light damage to buildings. 6.0 -6.9 It can cause severe damage in areas where many people live. 7.0 – 7.9 Major earthquake causing severe damage. 8 or greater Great earthquake, generates total destruction to nearby communities.

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