The is located in one of the most regions of the world, where the tectonic plates of Eurasia, Africa, Arabia and Anatolia interact. This highly complex geological environment has caused, over time, a series of devastating earthquakes throughout the country.
One of the deadliest was the 1939 Erzincan earthquake, which killed more than 30,000 people. Since then, scientists have noticed a striking pattern: large and destructive earthquakes seem to gradually “move” westward along the North Anatolian Rift.
Many researchers now estimate that the most likely trigger point for the next big earthquake is under the Sea of Marmara. This particular section of the fault has not produced a major earthquake in more than 250 years, raising concerns that the accumulated stress is increasing with time. Despite decades of research, however, the exact structure of the fault beneath the seabed of the Sea of Marmara has remained unclear, limiting scientists’ ability to determine where a future earthquake might start and how its effects might be contained.
The first 3D electromagnetic model of the fault
To fill this gap, a research team led by Dr. Yasuo Ogawa, emeritus professor and researcher at the Tokyo Institute of Science Multidisciplinary Resilience Research Center, in collaboration with Dr. Tulay Kaya-Eken, assistant professor at Boğaziçi University, Turkey, conducted an extensive study of the area beneath the Sea of Marmara.
The research, published in the scientific journal Geology, presents the first complete three-dimensional (3D) model of this critical underground region, offering new data on the physical processes that determine how and what.
To create the model, scientists used extensive magnetotelluric measurement data from more than 20 stations that had been installed in the past. These stations record small changes in the Earth’s electric and magnetic fields, which are caused by structures deep below the surface.
Through a process known as ‘3D inversion’, the team was able to reconstruct a 3D map of the region’s electrical resistivity, at depths reaching tens of kilometers below the sea floor.
Zones of weakness and “locking” of the fault
Analysis of the model revealed a complex mosaic of regions of high and low electrical resistance. As the presence of liquids, such as water, reduces the electrical resistance, low resistance zones are considered mechanically weaker, while high resistance areas are stronger and “locked”.
“We believe that the high resistivity anomalies indicate areas of stress accumulation, shedding light on the mechanisms underway in this critical region,” Dr. Ogawa points out.
According to the team’s findings, future strong earthquakes may start at the boundaries between weak and strong parts of the crust, or at the edges of regions of high resistance.
Overall, the results bring scientists one step closer to answering a question of utmost importance to millions of people in Turkey. As Ogawa notes, “our findings can be used to estimate the location and potential magnitude of future megaearthquakes, with important implications for disaster prevention and management.”
Studies of this type may in the future help to reduce the loss of human life and property damage when the next major earthquake occurs along the North Anatolian Rift.
