The Turkish metropolis of Istanbul is threatened with a natural disaster.Image: imago
Istanbul is standing on a geological time bomb – and experts agree: a mega-earthquake is statistically long overdue.
December 14, 2025, 05:00December 14, 2025, 05:00
Ellen Ivits, Amir Selim / t-online
In the early morning of February 6, 2023, a severe earthquake with a magnitude of 7.8 struck the border region between Turkey and Syria. Just hours later, a second earthquake, almost as strong, followed. The proximity of both epicenters and the extraordinary magnitude made the event particularly devastating. In both countries, a total of over 62,000 people died and more than 125,000 were injured.
The quake occurred at a geologically sensitive point – where three earth’s plates meet: the Anatolian plate, the Arabian plate and the African plate.
Tensions in this area are erupting along two major fault zones: the East Anatolian Fault, which runs across Turkey, and the Dead Sea Transform Zone, which extends into Africa.
Danger at a geological fault line
Further west in Turkey, an even more severe earthquake is looming – and has been for some time. A so-called mega-earthquake could destroy the metropolis of Istanbul. Istanbul lies dangerously close to an active geological fault line. The North Anatolian Fault stretches across Turkey into the Sea of Marmara. It separates the Eurasian plate from the Anatolian plate – and there the plates are continuously shifting against each other – at a rate of a few centimeters per year. This constant movement is enough to build up enormous tension in the rock.
Particularly striking is a section of the fault that lies directly beneath the Sea of Marmara. This part was seismically inconspicuous for decades – no significant earthquakes were recorded there. This is exactly what geoscientists see as a warning signal.
A geologically “tangled” zone in which tensions build up unnoticed over a long period of time is particularly dangerous. It is also known from the historical earthquake chronology that severe earthquakes have occurred in this area several times in the history of the earth.
This long phase without an earthquake does not mean the all-clear – but on the contrary: it indicates that enormous tensions have accumulated beneath the earth’s surface that could discharge at any time.
“An earthquake is overdue”
These can trigger an earthquake with a magnitude of at least 7 – destruction would then occur in populated areas. At magnitude 8 or even nine there is a risk of severe damage and destruction.
The problem for the 16 million inhabitants: The metropolis is poorly prepared because of the weak structure of the buildings, says Marco Bohnhof to t-online, he is a scientist at the German Georesearch Center in Potsdam.
Although there are strict building regulations due to the risk of mega-earthquakes, hardly anyone adheres to them. «An earthquake is overdue. Statistically, one happens there every 250 years. The last major earthquake occurred in 1766,” said the expert. The concrete probability of a mega-earthquake in the coming decades is up to 80 percent. This was shown by data from various models.
Istanbul would not be able to withstand a strong earthquake
Earthquake researcher Naci Görür agrees with this, as he explains to the German Press Agency. There are 100,000 buildings in serious danger of collapsing, “hundreds of thousands will die,” he warns. In purely mathematical terms, it could be in the millions. Neither the local government of Istanbul, the central government nor the population are really aware of the danger, said Görür. “Measures to make cities in Turkey resilient to earthquakes are not sufficient.”
Many buildings that would collapse in a severe earthquake have not yet been upgraded, warned Sükrü Ersoy, a geology professor at Yildiz Technical University. “And given the high population density, damage is difficult to avoid, even with appropriate planning.” Turkish Urban Development Minister Murat Kurum said Istanbul would not be able to withstand an earthquake. A total of 1.5 million apartments and commercial units would be considered at risk of earthquakes.
The probability of an earthquake is increasing
The German geophysicist Dietrich Lange from the Geomar Helmholtz Center for Ocean Research also warned in an interview with t-online in 2023: “We know from historical records that there have been severe earthquakes in the region,” says Lange. There is a 30-kilometer-long gap in the underground south of Istanbul where the tension between the earth’s plates has not been released for a long time. This is extremely dangerous:
«It’s like a spring that is stretched out. The longer it gets, the more tension the spring builds up.”
The epicenter of the expected quake is about 15 kilometers from the city in the Sea of Marmara. The Kandilli earthquake monitoring station puts the probability of an earthquake with a magnitude of over 7 by 2030 at 60 percent.
Geophysicist Tom Parsons of the US Geological Survey (USGS) calculated the probability of a magnitude 7 or higher quake in the region within a 30-year period to be 35 to 70 percent. That was in 2004. More than 20 years have now passed – which means that the probability of occurrence tends to be even higher today.
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