Two giant tears found in tectonic plate beneath Iran, study says

Researchers led by a team from the Chinese Academy of Sciences have found evidence of two giant tears in the Arabian Plate beneath southeastern Iran, according to a study published in Nature Geoscience and reported by ScienceAlert.

The tears and how they were found

The team used a network of 69 seismic monitoring stations to detect vibrations from distant earthquakes. The recordings were taken between March 2017 and September 2018. Because vibrations change speed based on rock temperature and density, the data allowed the researchers to build a picture of structures deep underground.

The study identified one horizontal tear where the Zagros collision zone meets the Makran subduction zone, and a smaller vertical tear closer to the surface near the Makran Trench.

Why the plate is tearing

The researchers say the main cause is a mismatch between two types of rock in the plate. One part is an oceanic slab that was once part of the ancient Neo-Tethys Ocean. Its basalt rock is heavier and thinner and is being pushed beneath a neighboring plate in a process called subduction.

The other part is continental rock, which is thicker but less dense, with lighter, granite-like ingredients. This rock resists being forced underground and instead forms mountains when it meets resistance. The researchers say that difference is what tears the plate.

In the Makran subduction zone, the oceanic lithosphere has subducted to depths of at least 450 km, while in the Zagros collision zone to the west, the continental lithosphere has subducted no deeper than 300 km, resulting in east–southward slab tearing and detachment, according to the researchers.

The second, vertical tear probably began at the junction between the Makran Trench and a transform boundary and has propagated southward as the continental plate advances northward. The researchers suggest plate motion, rather than rock type differences, is the main driver of that tear.

Whether the tears will meet

The study models indicate the rips have been progressing for several million years. The two tears initiated independently, but the boundary segment between them is progressively consumed as tearing advances. The researchers expect this to eventually drive coalescence of the two tears.

"While the two tears initiate independently, the intervening continental-oceanic boundary segment is progressively consumed as tearing advances," write the researchers.

"This progressive linkage is expected to eventually drive coalescence of the two tears."

The researchers say hot magma already appears to be filling some of the gaps caused by the ruptures. The next question is how the tears and their possible merging might affect volcanic activity in the region.

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Sources

• sciencealert.com: Scientists Discover Two Enormous Tears in a Tectonic Plate Beneath Iran : ScienceAlert
• aroundprague.cz: Scientists Find Two Giant Tears in Plate Under Iran, Likely to Merge

This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.