Scientists can explain solid earth activity - such as earthquakes and volcanoes - in the context of the "tectonic plate" theory dating back 50 years.
This theory assumes that the outer crust of the Earth (the lithosphere) is divided into plates that move relative to each other, and its activity is concentrated along the boundaries between them, but the scientific community does not know how these tectonic plates originated.
In a new study published by Nature Communications on July 17, an international team of researchers from China, Hong Kong and the United States provided the answer to this question, taking into account the timing of its occurrence.
An old hypothesis with a new form
The new hypothesis appears very similar to an idea that has been around for decades, but this study came to be reviewed.
It is known that tectonic plates mix with each other and rearrange themselves from approximately 3.3 to 4.4 billion years ago, so this tectonic movement that recycled the Earth's crust and lasted for billions of years makes it very difficult to know how the tectonic plates originated, so a few years ago researchers developed a model It shows that tectonic plates were formed for the first time in a process similar to the displacement currently taking place.
Some parts of the Earth's crust are submerged under others, and then the chain reaction of these impulsive pieces that lasted for thousands of years begins.
But the new study presents a completely different model, as it suggests that the earth's crust - which was then formed billions of years ago - became hot, causing it to expand and then cracked, forming what we now know as tectonic plates, and therefore it came as a result of the thermal expansion of the Earth's crust.
Expansion or heat contraction?
The hypothesis of the expansion of the earth is not considered a new idea, as this idea was proposed in the 19th century to explain some of the geographical features observed on the ground, such as mountains.
Before the discovery of the theory of plate tectonics in the 1960s, some scientists such as Charles Darwin assumed that the majority of earthquakes, mountains, and terrestrial mass distributions on Earth were a result of Earth's expansion processes.
Since the main internal heat source of the Earth is radioactivity, which is considered to be continuously decreasing as a result of the degradation of radioactive elements over time, so we are most likely to face a state of contraction and not thermal expansion, and therefore the validity of the Earth's expansion hypothesis has been dropped.
So how does this recent study restore the validity of this assumption again?
Thermal conductivity
"The answer lies in the mechanisms of heat loss that are likely to have occurred during the early Earth ages," says Alexander Webb, a planetary scientist at the University of Hong Kong who is involved in the study, according to the report published by the Science Alert website.
Webb explains this mechanism by saying, "This lies in the volcanic creep that carried hot lava from the depth of the earth to its surface, and was a major cause of early heat loss, which changed everything, and the accumulation of cooled lava contributed to the dumping and cooling of the rocky outer layer of the Earth."
Consequently, the process of emptying the earth's hot surface and accumulating it on the surface eventually required the sinking of the original (cold) surface layers to the bottom, and because the earth was generally cooled, this led to the slowing of the volcanoes.
But the Earth's rocky outer layer has remained increasingly warm - as the recent study says - after thermal conductivity with the Earth's deep hot material, and thus the warming of the Earth's outer layer due to thermal conductivity was the cause of its expansion.
However, it is important to note that this study presents a new hypothesis that needs more evidence to understand what happened on the surface of the early Earth, and how tectonic plates formed.