Threat: Why is the tectonic plate splitting beneath Tibet?

The Himalayan and Tibet region is the greatest example of the geological phenomenon known as “continental collision”.

It arose from the collision between pieces of Earth’s crust that, around 60 million years ago, belonged to the India and Eurasia.

The friction was so strong that the Indian plate was pushed beneath the Eurasian plate and, as a result, what we know today as the highest mountains in the world emerged.

The movements of these plates, however, continue to this day and generate concern. There are two basic theories that previously explained this phenomenon.

One said that the Indian plate is “floating” and that, therefore, it slid under the Eurasian plate and formed Tibet.

The other claims that the Indian plate actually went through a wrinkling process, as if it were paper, and Tibet would be a fold.

But during the 2023 conference of the American Geophysical Union, a third thesis about this story emerged.

Researchers from institutions in the China and the US said that the Indian plate is “delaminating”, that is, the upper part is peeling off to support the weight of Tibet, while the lower part sinks into the mantle.

Configuration of tectonic plates in the world – Photo: Internet/Reproduction

How did they reach this conclusion?

The team of scholars, linked to the China Oceanic University in Qingdao, collected S-wave data (from “up and down” shear) at 94 seismic stations located in eastern and southern Tibet. The data were then compared with those of P waves (“back to front”).

The US team, from Stanford University, looked for another alternative. As it is impossible to dig a tunnel to reach the mantle of Earththey used helium-3.

This component is a very rare gas isotope on Earth that can be released by the planet’s core, so it is possible to assess whether the mantle would be close to the northern surface of Tibet.

The measurement was carried out at 200 Tibetan springs and revealed a helium-3 escape pattern in northern Tibet.

This shows that the mantle is close to the surface. In the south, what leaked was helium-4, an isotope that proves that, there, the plate is still intact and forms a barrier that prevents other helium from passing through.

What does it look like now with the new discovery?

Scholars believe that this entire process was facilitated by the shape of the Indian plate, which is thicker in the north and thinner on the sides.

As a result, the center sinks faster and any slight pressure from the upper mantle results in wear and tear of the lower part. Therefore, in the future it is very likely that earthquakes in the region.