The Tectonic plates in Mexico Are very peculiar because their way of converging is different from that of other regions of the planet.
The surface of the earth did not always have the appearance we see today. The continental masses float on a magma or molten rock, and are divided in plates that rub and collide with each other, which gives origin to the mountains, marine abysses and earthquakes.
In 1620, Sir Francis Bacon, an English philosopher very devoted to political affairs, who devoted the last years of his life to science, noted how the coasts of the American and European continents on the map fit perfectly.
Based on this a hypothesis was elaborated in 1912, by German Alfred Wegener -supported by the finding of similar fossils in places far away from the planet- that the continents were moving in a viscous mantle.
These theories lacked credibility until the 1960s, when the tectonic plates .
It was determined that the movement of the plates has been developing for millions of years and that there existed a supercontinent called Pangea that grouped all the present continental surfaces, separated thanks to the reconfiguration and constant displacement of the Lithosphere .
In the zones of convergence of plates several phenomena can happen. If one plate moves on another, it is said that there is a subduction and as a result a rise, producing mountain chains and volcanoes. If there is a collision, mountains occur and there is high seismicity or probability of earthquakes occurring.
Some countries like Mexico own part of their territory in several zones or tectonic plates. As a consequence, they are areas of high seismic activity and volcanism.
The peculiar tectonic plates of Mexico
The countries where tectonic plates converge have similar characteristics. However Mexico is different.
For example, when the plates converge, earthquakes have their origin at a depth of 600 km and yet in Mexico, an earthquake has rarely been detected below 100 km.
In most of the subduction zones, volcanic arcs parallel to the trench left by the plates originate. In Mexico this arch moves away from the trench at an angle of about 15 °.
In most subduction zones, large earthquakes occur with a frequency of a few hundred years. In Mexico it occurs only on the coast, and in addition has been detected a modality called"silent earthquake", undetectable and with a duration of up to one month.
Most of Mexico is located at the bottom of the large American plate. In the south part it converges with the plate of the Caribbean.
This plate covers both the Caribbean Sea and most of the Antilles, including much of Cuba, a part of South America and almost all of Central America. From Mexico, the Caribbean plate contains south of Chiapas.
The California peninsula is located on the Pacific plate, which moves northwest and below the American plate. In the zone of encounter of these two plates is located the fault of San Andrés, that is famous for its high seismic activity.
The Rivera Plate is a small plate located between Puerto Vallarta and the south of the California peninsula. Its movement is towards the southeast, bordering the Pacific plate and submerging under the North American plate.
The Orozco and Cocos plates are oceanic crusts located in the southern part of Mexico. The collision between the two was the cause of the great earthquake of 1985 in Mexico City as well as the most recent earthquake of 2012.
Tectonic plates may have three types of edges between them. They are said to be divergent if the plates move away from each other, leaving a space where there may be volcanic eruptions and earthquakes.
On the other hand, they are convergent when the plates are rather well, and one of the following cases may occur:
1- Subduction limit : One plate is folded down the other, into the earth. This can occur on both the continental and oceanic sides, creating a fringe or crack, as well as a mountainous and volcanic chain.
2- Collision Limit : Two continental plates approach each other, creating great mountain ranges like the Himalayas.
3- Friction limit : Where the plates are separated by tranches of faults that transform, giving rise to straight and narrow valleys in the ocean floor.
Extra concepts on tectonic plates
Current theory suggests that tectonic plates have a thickness of between 5 and 65 kilometers.
The Earth crust Is divided into approximately twelve plates, which drift in different directions at different speeds, a few centimeters a year, as a result of Convection currents Thermal insulation of the earth's mantle.
Major tectonic plates
Some of these plates contain sea and land, while others are totally oceanic.
Extra concepts about f Allas
When the tectonic plate forces exceed the capacity of shallow rocks (located 200km deep), they fracture resulting in a discontinuity.
The fault zone is called the rupture zone, and it has a parallel slip of the rocks.
The active faults are those that continue to slide today, while the inactive ones have more than 10 thousand years without presenting movement. However it is not ruled out that an inactive fault could eventually be activated.
If the movement of the fault is gradual and the tension is slowly released, the fault is said to be asismic, whereas if the movement is abrupt, the fault is said to be seismic. A large earthquake is caused by d jumps between 8 to 10 meters between the edges of a fault.
References
- Continental drift, Alfred Wegener. Recovered from: infogeologia.wordpress.com.
- Evolution of Tectonics in Mexico. Retrieved from: portalweb.sgm.gob.mx.
- Francis Bacon. Recovered from: biografiasyvidas.com.
- Tectonic plates of Mexico. Retrieved from: webshop.blogspot.com.
- Retrieved from: www.smis.org.mx.
- Tectonic Setting of La Primavera Caldera. Retrieved from: e-education.psu.edu.
- The unusual case of the Mexican subduction zone. Retrieved from: tectonics.caltech.edu
- Which tectonic plates affect Mexico? Recovered from: geo-mexico.com.