Deep beneath the surface of Turkey, scientists are uncovering subtle but powerful movements that are reshaping the continent's crust.
Studying ancient lava flows that poured, solidified and later fractured along one of Turkey's major tectonic systems has given scientists new clues about how continents tear and deform over time – and improved our understanding of earthquake hazards in the region.
A team of researchers from Curtin University in Australia has discovered that the Tuz Gölü Fault Zone—a geological structure that stretches more than 200 kilometers and is clearly visible in satellite imagery—is slowly widening. This slow separation between crustal blocks creates a rare opportunity to examine how tectonic forces tear apart continents where plates meet.
Professor Axel Schmitt, from the John de Laeter Centre and the School of Earth and Planetary Sciences at Curtin University, explains that the findings resolve a long-standing controversy about the nature of movement along the fault, and represent an important advance both in assessing earthquake risks and in improving global models that describe how continents deform.
"While Turkey is best known for its strike-slip faults that cause powerful earthquakes, our study confirms for the first time that the Toz Gulu fault is an extensional fault," says Schmitt. "This means that the ground on either side of the fault is moving away from each other—not sliding past each other, as previously thought."
Reconstruction of ancient lava flows
The researchers focused on lava flows from the Hasandağ volcano, which previously flowed across the fault, solidified into rock, and then broke again during later earthquakes.
"Several lava flows from the Hassandag volcano flowed across the fault, cooled – and were later separated by earthquakes," explains Schmitt. "We were able to reconstruct their original shape and determine their age. This allowed us to track how rocks that were once connected – moved apart over time."
The findings, he says, paint a clear picture: the fault is stretching at a rate of about one millimeter per year, rather than moving mainly horizontally. “Understanding such movements is important not only for assessing earthquake and volcanic risks in the region,” adds Schmitt, “but also for improving global models of continental deformation.”
The researchers used a combination of remote sensing data with advanced analyses at the John de Laeter Centre, including ion microprobe and helium dating at the Western Australia ThermoChronology Hub (WATCH). These methods allowed them to determine the precise age of the lava flows and measure how far apart their parts had drifted over thousands of years.
Associate Professor Martin Danišík, a research associate at the John de Laeter Center, explains that tiny zircon crystals within the lava served as natural “time clocks.” These crystals capture helium created from the radioactive decay of tiny amounts of uranium and thorium, thereby preserving a chronological signature of the lava.
"By measuring uranium, thorium, and helium in zircon, we can determine exactly when the lava flows erupted, flowed across the fault, and then cooled," says Danishik.
Revealing the hidden movements in the landscape
Dr. Janet Harvey, a remote sensing expert and research partner also from the John de Laeter Center, notes that unlike the more active faults in northern and eastern Turkey, earthquakes on the Toz Golu fault occur less frequently – making it especially important to study landscape and crustal changes over geological time, beyond what can be learned from modern seismograph records alone.
“The fault is located at a pivotal point where the Eurasian, Arabian and African plates all influence each other,” says Harvey. “Studying its movements helps us understand how strain is distributed when continents collide—insights that can be applied to other parts of the Alpine–Himalayan mountain belt and other areas of continental deformation around the world.”
She says the study highlights the importance of reexamining long-held geological assumptions. "The combination of remote sensing data, precise rock dating, and reconstruction of lava flow geometry allows us to directly measure how the crust responds to the enormous tectonic pressures. In this case, it clearly shows that the crust in central Anatolia is not just sliding—it is tearing apart."
The study was published in the journal: Communications Earth & Environment
