PLATE OF COCONUTS: LOCATION AND GENERAL CHARACTERISTICS - GEOGRAPHY - 2024

The Cocos plate, also called the Coco plate, is a relatively small oceanic plate located just west of Mexico, in the Caribbean. The plate is adjacent to the North American, Caribbean, Rivera, and Pacific plates. One of the most significant tectonic processes in the North American Caribbean region occurs on this plate.

It is considered that the tectonic movements of this layer were the main responsible for the earthquakes that devastated Guatemala and Mexico almost 20 and 40 years ago, respectively. The Cocos plate is one of the smallest tectonic layers on the planet, along with the Scotia, Arab and Caribbean plates.

Yet it is one of the fastest moving plates, advancing more than 75 millimeters each year. Its movement causes subductions with the adjacent plates, which causes earthquakes throughout the Central American region.

Location and states affected

The proximity of the Cocos plate with the Mexican coast, and with the Central American region in general, means that its movements can cause earthquakes in any Central American country that is close to the coast.

As a consequence of this, Chiapas suffered an earthquake in 2017, which is believed to be a consequence of the tectonic movements of this terrestrial plate.

The Mexican states most affected by the movements of the Cocos plate are: Chiapas, Oaxaca, Guerrero, Michoacán, Jalisco, Nayarit, Colima, Sonora and Baja California Sur.

The Cocos plate is found on the west side of Mexico. To the north it borders the North American Plate, which encompasses the entire north of the continent. To the east it limits with the Caribbean plate, which is located in the Caribbean Sea and in the north of South America.

To the west, the Cocos plate borders the vast Pacific plate, while to the south it borders the Nazca plate, with which it usually shares tectonic movements and causes tremors on the planet's surface.

General characteristics

Origin

The Cocos plate originated millions of years ago, after the ancient Farallon plate fractured into several small plates.

The Farallon plate was an ancient plate located in what is now North America, which fragmented into several pieces after the separation of Pangea in the Jurassic Period.

With the passage of time, the subduction processes of this plate caused it to be located completely below the modern North American plate. All that remains of this plaque are the plaques of Juan de Fuca, Gorda, and Explorer.

Furthermore, both the Nazca plate and the Cocos plate are the product of the subduction of this ancient prehistoric plate. A large part of all of North America is made up of remnants from the Farallon plate subduction.

Relationship with the expansion of the sea floor

Plates like Cocos are created after a process called "seafloor expansion" occurs. This theory ensures that the ocean's crust is formed in conjunction with the creation of underwater mountain ranges.

The Cocos plate was formed as a result of the solidification of magma, which leaves the center of the Earth after encountering ocean water.

The characteristics of the expansion movements of the sea floor are the same as the Cocos plate, which makes it share the same physical peculiarities as the rest of the other large terrestrial layers.

This is only in regards to its composition; the movements of each one are different and, in many cases, independent.

Material and movement

The Cocos plate - like the rest of the planet's tectonic plates - is located just above the Earth's asthenosphere, a layer of stone and minerals that is partially melted. The texture of this layer is what allows the displacement of the layers of the planet.

The plates usually do not move more than a few millimeters a year. However, Cocos is one of the most displaced, partly thanks to its location with respect to the rest of the planet's plates.

The movement of the plates is related to each other. That is, if the Nazca plate is displaced, the Cocos plate will also move in response to the initial movement of its adjacent one.

The Cocos plate is rigid and does not melt easily in the heat of the asthenosphere; This helps the movement of the layer. However, subduction shocks between one layer and another cause sudden movements that are felt on the surface in the form of earthquakes.

Furthermore, when two plates are divergent, the movement they cause causes magma to be expelled from the depths of the planet, which in turn helps the movement of the plates.

Possible interactions with the Pacific and Nazca plates

In addition to the motion that occurs when two divergent layers interact with each other, oceanic plates can have convergent connections. When two plates converge, it means that they are both approaching each other.

In this case, the plate that is in a denser state is the one that ends up sliding under the other plate. For example, in an encounter between the Nazca plate and the Cocos plate, the denser boundary is dragged, which causes the layer to be dragged to the bottom of the less dense one.

This process leads to the formation of volcanoes (after several centuries of tectonic movements). Fractions of the densest plate are "recycled" by Earth and can rise again thousands of years later.

This type of movement is also responsible for forming mountains over time. Obviously, most of these movements occur over the course of several years.

Ability to cause earthquakes

One of the reasons why earthquakes are so common is because of the friction that is generated when the layers collide without meeting in a divergent or convergent way. The least devastating interaction for layers is transformation.

When a transformation movement occurs, no subduction occurs. Instead, the plates move relative to each other and cause a great deal of friction.

This type of friction is not capable of producing mountains or volcanoes, since the ground does not rise. However, these frictions bring a great risk of earthquakes to the surface.

When friction is generated between two plates of the Earth, the greatest consequences are seen in the highest layer of the lithosphere, where humans live.

Composition

Oceanic plates, such as the Cocos plate, are made up of a type of stone called basalt rock. This rock is much denser and heavier than the material that makes up the continental plates.

For the most part, continental plates are made up of granite, which is made up of minerals such as quartz. Quartz, compared to basalt rock, is much lighter in composition.

The layer of the Earth's crust that lies beneath oceanic plates is typically no more than 5 kilometers thick. This is due to the high weight of the basalt minerals that make up these plates.

On the other hand, other types of plates that are continental -such as the North American plate, neighboring the Cocos plate-, have a much thicker lower crust. In some cases, the crust that is located below the continental plates is more than 100 kilometers thick.

These compositions affect the interactions that the plates have with each other. The density of the oceanic plates causes the movements between layers to make subduction keep the continental layers at the top, while the oceanic plates move to a lower plane.

These movements occur slowly but continuously on all plates on the planet, including the Cocos plate.

Boundary characteristics

The limits that separate the Cocos plate from the rest of the layers that surround it cannot be appreciated with the naked eye, since they are located below the earth's surface, in the oceans.

However, it is possible to determine the exact place where these limits are thanks to modern satellite technology.

The limits or borders of the Earth's plates are usually centers where there is a lot of volcanic activity. In addition, it is there where earthquakes are mainly generated, since these limits are the place where different layers collide with each other.

Changes

Cocos plate usually changes its shape over time. In itself, the shape of the Cocos plate is quite irregular and does not follow a certain geometric pattern. Time and the subduction and transformation movements cause the layer to fracture, changing its shape over the centuries.

It is likely that the Cocos plate will disappear completely in the future, if subduction movements cause it to move towards the lower part of a neighboring continental layer.

References

1. What is a tectonic plate ?, US Geological Survey Publications, 1999. Taken from usgs.gov
2. Plate Tectonics, JB Murphy & TH van Andel in Encyclopaedia Britannica, 2017. Taken from Britannica.com
3. Seafloor Spreading, Encyclopaedia Britannica, 2017. Taken from Britannica.com
4. Cocos Plate, A dictionary of Earth Sciences, 1999. Taken from encyclopedia.com
5. Cocos Plate, Encyclopaedia Britannica, 2011. Taken from britannica.com