Scientists warn that tectonic plate under Tibet may split in two

The Indian tectonic plate, which lies beneath the world's highest mountains, the Himalayas, appears to be slowly delaminating as it slides beneath the Eurasian plate. This is indicated by the analysis of earthquake waves passing under Tibet, as well as signal gases rising to the surface.

This is stated in a study published on the Ess Open archive preprint site. Scientists admit that they had no idea that continents could behave in this way.

The collision of the Indian and Eurasian tectonic plates began about 60 million years ago. At that time, India was an island that collided with Eurasia so violently that the surface was curved, forming the highest mountains on Earth.

However, the formation of the Himalayas is only part of what happened during the collision of the tectonic plates. At a depth of tens of kilometers, a kind of confrontation, which now hints at the appearance of a rift, continues.

As the scientists explained, continental tectonic plates are thick and buoyant, so, unlike oceanic plates, they do not easily sink into the mantle during collisions. Moreover, scientists believe that the Indian plate is either still resisting sinking into the mantle, sliding horizontally under Tibet, or is crushed along the front edge of the collision, causing the lower part of the plate to sink into the mantle.

A new study, according to Science, indicates that something stranger may be happening to the Indian plate. Scientists have found evidence that it is "delaminating" as it slides under the Eurasian plate. As a result of this process, the dense lower part is separated from the upper part. The researchers also found evidence of a vertical fault, or rupture, at the boundary between the separated part of the plate and its intact neighbor.

Douwe J.J. van Hinsbergen, a geodynamicist at Utrecht University, said that scientists did not even know that "continents can behave in this way." According to him, the discovery is "quite fundamental" for the science of the solid Earth.

He believes that the study could help scientists better understand the formation of the Himalayas and perhaps even the risk of earthquakes in the region.

For his part, Fabio Capitanio, a geodynamicist at the University of Monash, noted that there are still many uncertainties about the process, so the research will need to continue.

Previously, scientists had assumed that such a separation of tectonic plates was possible because they are formed of floating crust and denser upper mantle rock, so the plate is quite capable of splitting along a weak interface between the layers. But, as van Hinsbergen noted, this is the first time that the phenomenon has been detected directly on a sinking plate.

Scientists said that the Indian plate has always differed in thickness and composition, which explains the crescent shape of the 2,500-kilometer Himalayan front. The point is that the thinner "wings" of the oceanic crust surround the thick middle of the continental crust. During the collision with the Eurasian plate, the oceanic plates easily sink under it, while the thick continental crust collides with Eurasia like a battering ram.

This difference in sinking speed ultimately led to the Indian plate being pulled and torn in different directions.

Scientists also noted that the ideal location for potential faults is an area in northeastern India, near Bhutan.

During the study, the researchers found evidence for this theory, as well as evidence that the lower part of the Indian plate is not just in the process of stratification but has probably already separated from the upper part.

In particular, the data show that to the west of the alleged rift, the bottom of the Indian plate lies at a depth of about 200 kilometers. Here, scientists believe, the plate remains intact. While in the east, the plate is likely to have split in two as mantle rocks flow out at a depth of about 100 kilometers.

Understanding how the continents collide sheds light not only on the modern landscape of the Earth but also on the danger posed by earthquakes that can occur along ancient scars from the collision of the continents.

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