Scientists Find Two Giant Tears in Plate Under Iran, Likely to Merge

Researchers have found two giant tears in a tectonic plate deep beneath southeastern Iran, and computer models indicate they will eventually link up, according to ScienceAlert. The work, led by a team from the Chinese Academy of Sciences, was published in the journal Nature Geoscience.

The tears sit in the Arabian Plate. Geologists rarely see two such ruptures in the same place at the same time, which makes the region a useful natural laboratory for how oceans close and continents collide.

How seismic stations revealed the tears

The team used a network of 69 seismic monitoring stations to record vibrations from distant earthquakes. Those vibrations change speed depending on the temperature and density of the rock they pass through, so the recordings can be used to build a picture of structures far underground.

The data were collected between March 2017 and September 2018. They showed one horizontal tear, located 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 ripping apart

The main cause is a mismatch in the rock itself. One part of the plate is oceanic slab, once part of the ancient Neo-Tethys Ocean. Its basalt is heavier and thinner, and it is being pushed beneath a neighboring plate in a process called subduction.

The other part is continental rock. It is thicker but less dense, with lighter, granite-like ingredients. This kind of rock resists being forced underground and tends to build mountains instead. The researchers say that difference in behavior is what tears the plate.

In the Makran subduction zone, the oceanic plate has sunk continuously to depths of at least 450 km, the team reports. In the Zagros collision zone to the west, the continental plate has gone down no deeper than 300 km. That gap leads to the slab tearing and detaching toward the east and south.

The second, vertical tear is different. The researchers say it probably began at the junction between the Makran Trench and a transform boundary, where plates slide past one another. They suggest it has spread southward as the continental plate pushes north. In their view, plate motion rather than rock type is the main driver of that tear.

Why the tears are expected to meet

According to the study's models, the rips have been progressing for several million years. The two tears started independently, the authors write, but the stretch of continental-oceanic boundary between them is gradually being consumed as the tearing advances. They expect that process to eventually merge the two tears.

This is a model-based projection, not something observed directly, and it plays out over geological time.

Why it matters

For most readers the findings are about understanding Earth rather than any change they would notice. The tears are developing over millions of years, and ScienceAlert noted that humans may be long gone before they join.

For scientists, the region offers a rare view of a brief, early stage when an ocean floor stops sinking and continents begin to collide. The researchers describe this transition as a key stage in the Wilson Cycle, the long process by which oceans form, widen and then vanish as plates move. They say its details have been unclear because there have been few observations of structure at depth. Here, the Neo-Tethys Ocean is in its final stages.

What researchers want to know next

The next question is how the tears, and their eventual merging, might influence volcanic activity in the region. ScienceAlert reported that hot magma already appears to be filling some of the gaps opened by the ruptures. The study does not settle how that will shape volcanism over time, and that remains the open question for follow-up work.

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Around Prague, based on reporting by ScienceAlert