There are several cities around the world that have small shocks called microseisms. The fact that they happen spontaneously and sporadically does not set off alarm bells, but when these microearthquakes happen continuously that is when they alert the population.
This movement is caused by the union of tectonic plates, but in other cases it occurs due to the volcanic activity that occurs in the area. However, it is essential to know other possible consequences, since it is necessary to know its origin.
What are microseisms?
Microseisms are small shakes or mini earthquakes that happen on the surface of the earth. They generally go unnoticed or absent and usually warn that something may happen, such as a volcanic eruption.
When these microseisms manifest themselves, they are usually associated with the union and movement of tectonic plates. On other occasions it is related to the volcanic activity in the area. This information can take advantage of the fact that a volcanic eruption is approaching, which can be harmless or catastrophic.
In other cases it can be associated with a accumulation of energy beneath the earth, in many cases caused by the event described above.
Are these microseisms dangerous?
Microseisms do not usually represent a significant risk. Are small movements and that have a minimum Richter scale, between 2.0 and 3.0. Given this fact, its ability to create damage is minimal or non-existent, but people who feel these movements can create nervousness.
To know in more detail the magnitude of the movements, there is a list of degrees and their repercussions within society. According to many Universities, knowing this data is important to categorize them.
- 3.5 – 5.4 It is often felt, but causes only minor damage.
- 5.5 – 6.0 Causes light damage to buildings.
- 6.1 – 6.9 It can cause severe damage in highly populated areas.
- 7.0 – 7.9 Major earthquake. Causes serious damage.
- 8 or greater Great earthquake. Total destruction of nearby communities.
When these microseisms occur The damage is almost non-existent. They cannot even be perceived 8 kilometers around the epicenter, so they are harmless.
There are areas on our planet where These movements are constant due to being in a conflict zone. They manifest themselves in an environment of intense telluric movement or within a Neovolcanic Axis.
Do microseisms exist in Spain?
In reality, they exist in many parts of the world, especially in the country of Mexico. Within Spain there are areas with greater seismic risk that do not usually lead to greater relevance. Below, we detail the most conflictive points, given that two tectonic plates converge in our country, the Eurasian and the African:
- northeast zone, in the Pyrenean mountain range, due to the Pyrenean fault.
- In the south, in the area of Andalusia, Murcia and Granada, due to the African plate under the Eurasian plate.
- In the Canary Islands, due to its volcanic origin. In this area, patterns of microearthquakes are recorded, especially on the island of El Hierro. This tectonic activity is also detected between the island area of Tenerife and Gran Canaria.
Small earthquakes and microseisms recorded in Spain
There is a Official Site that records the microearthquakes that occurred in the last 10 days. It is a table that shows where they have occurred and what scale. Obviously, this type of tremors do not exceed 2,5 magnitude points.
There is news in Spain that has recorded multiple tremors and they have amazed scientists. We have observed it in Asturias and León, with 45 microearthquakes that occurred under the Cantabrian mountain range and at a depth of 18 kilometers.
This event occurs in the Ventaniella fault and runs for 400 kilometers between the western coast of Asturias and the Duero basin. Between 2015 and 2017, a total of 45 earthquakes, with a magnitude less than 2 on the Richter scale and in all cases.
The epicenters were located under the Cantabrian mountain range, between Asturias and León. They were 18 kilometers deep, so they could not be detected by local people.
Teide also registers more than 600 microseisms at times, a type of activity that is expected because it is an area of active volcanic islands. These tremors can herald an eruptive process in the near future.
In the Tenerife area, up to 630 small-magnitude seismic events have been recorded just a few years ago. These movements were located between 9 and 12 kilometers deep, according to the Canary Islands Volcanological Institute (INVOLCAN).
In this case, the microseisms in the Canary Islands are related because they are a volcanic area. In other cases, said activity arises from being in an area susceptible to failures or a subsidence created by soft soils. This action is carried out by the pressure on the specific faults and in some cases they become more noticeable by the inhabitants of the area.
Different tremors, magnitudes and consequences
A magnitude less than 2 is called microseisms. They are almost not perceptible and up to 8.000 are produced per day. When we talk about a magnitude from 2 to 2,9, They are already considered minor earthquakes and become almost perceptible. Up to 1.000 tremors occur a day.
The largest earthquake that has occurred in history took place on May 22, 1960. It happened in the city of Valdivia, in Chile and its magnitude was 9,6. It is one of the most violent earthquakes that has been recorded on Earth, although the magnitudes on the Richter scale coincide at values up to 6,9. These values are not measured by intensity, since they often depend on the distance from the epicenter and not by its magnitude. If said tremor coincides near the surface and with susceptible local conditions, the results can be fatal.
There are magnitudes that are never unimaginable, a magnitude 10 would already be an apocalyptic or legendary earthquake. There are even earthquakes of magnitude 32, but they only occur on the solar surface. Other earthquakes become impressive on our planet, very occasional earthquakes of magnitude have been recorded. magnitude 9-9,9. They are devastating, affect thousands of kilometers and occur between 1 to 2 every 20 years.