Turkey rests atop one of the planet’s most restless junctions, with the Eurasian plate to the north and Arabian plate pressing from the south. Between them lies the Anatolian microplate, a piece of crust forced to slip westward, squeezed like a bar of soap between two hands. The major line of rupture that concerns Istanbul and the Marmara Sea is the North Anatolian Fault, a 1500 km-long, right-lateral strike-slip fault stretching from the mountains of Eastern Anatolia all the way to the Sea of Marmara. The East Anatolian Fault is where the Arabian plate pushes northward, producing earthquakes like the devastating series in early 2023 around Kahramanmaraş and Hatay. Additionally, the western Anatolian Extensional Province results in cities like İzmir, Manisa, Denizli, and Muğla frequently experience moderate earthquakes as the crust is literally pulled apart. Fault segmentation, stress transfer between segments and complex branching under the Marmara Sea make the region especially prone to a multi-segment rupture that can produce very large earthquakes.
The motions beneath Turkey are slow but ruthless. The Arabian plate presses northward at roughly 20–25 millimeters each year, while the Anatolian microplate slips west at about 21–22 millimeters annually. Along the North Anatolian Fault, the crust moves in the same order of magnitude — around 20–25 millimeters per year — quietly stockpiling strain until it can no longer hold. These numbers may seem insignificant, but added week by week, decade over decade the accumulated pressure becomes enormous.
The North Anatolian Fault is not a single fracture but a chain of interconnected segments stretching from east to west. Over the 20th century, this fault system ruptured in a sequential march westward, first Erzincan in 1939, then Niksar–Erbaa in 1942, Tosya–Ladik in 1943, Bolu in 1944, Abant in 1957, Mudurnu Valley in 1967, followed by the double blow of the 1999 İzmit and Düzce earthquakes. Each rupture transferred stress toward the next locked segment, advancing steadily toward the Sea of Marmara.
In recent years, Turkey has seen a noticeable increase in seismic activity across western provinces such as Balıkesir, Çanakkale, Manisa, and Denizli. Balıkesir, positioned within the western Anatolian Extensional Province, has experienced a series of moderate earthquakes that drew national attention. The significance of the Balıkesir earthquakes is not their indication of a larger event — science does not offer such straightforward warnings — but their reminder that the entire western half of Turkey is tectonically alive. It is not only the great North Anatolian Fault or far southeastern provinces that stir beneath the surface. Much of the country’s geology vibrates with constant adjustment, whether we feel it or not.
The faults beneath Balıkesir operate differently from those in the north. They are normal faults, created by the crust pulling apart, not sliding past itself. Their mechanics are distinct from the North Anatolian Fault, and they are not directly connected to the long-anticipated Marmara segment. For people living in Balıkesir, the impact is more than geological as Turks know the sensation of a small quake — the brief shudder, the pause in conversation, the instinctive upward glance as if listening for the next sign. In a city shaken repeatedly, each tremor is a reminder to inspect buildings, check emergency kits and note escape routes.
No discussion about earthquakes in Turkey escapes the gravity of Istanbul. The only major segment in this sequence that has not yet broken lies beneath the Marmara Sea, directly south of Istanbul. Under the calm surface of the water lies a system of basins — Çınarcık, Central, Tekirdağ — carved not only by water but by fault motion. These underwater segments are capable of producing a large earthquake. A city of 16+ million people, built on layers of history sits beside the most studied — and most worrying — segment of the North Anatolian Fault, the Marmara segment. Scientists agree on three points: a major earthquake will happen, it will likely be between magnitude 7.0–7.6 on the Richter scale and we do not know when it is coming. Beyond these points, predictions become informed attempts to describe the shape of an event whose timing remains unknowable.
Researchers typically outline three broad possibilities. The most studied scenario is a rupture in the western Marmara, near Silivri–Marmara Ereğlisi, which would send strong shockwaves across the European side. Older districts like Fatih and Eminönü, along with areas prone to liquefaction such as Avcılar, Küçükçekmece, Zeytinburnu, and Bakırköy, face especially high risk. A more severe scenario involves multiple fault segments giving way sequentially, producing a larger, longer earthquake that would affect both European and Asian sides. A third scenario imagines a rupture in the eastern Marmara, near Yalova–Tuzla, echoing the 1999 İzmit earthquake but shifted toward Istanbul’s own coastline. The Asian side, along with industrial corridors and critical infrastructure, would feel the strongest impact.
Despite their differences, all models indicate tens of thousands of buildings would be heavily or moderately damaged, and many more would experience structural stress. Bridges, viaducts, pipelines, and transport arteries would be pushed beyond their limits. Electricity, water, and telecommunications disruptions would likely spread across the city. Istanbul’s vulnerability is not due to unpreparedness, but its density and inherited building stock.
The question that haunts residents — “When?” — remains one science cannot answer. Experts say there is a substantial likelihood of a major earthquake within the next thirty years and grows each year the fault remains locked. But the precise moment will always remain out of reach. This uncertainty, more than any specific prediction, is what weighs on Istanbul and yet, daily life continues with remarkable flexibility, residents do not move through their routines in constant fear, but the awareness is always present. Conversations that once felt technical now spill into cafés and WhatsApp groups. A new vocabulary — shear walls, soft stories, liquefaction zones — has entered daily life. In the past decade, many Turks have become conscious consumers of safety, asking architects and landlords about ground studies, soil class, and compliance certificates.
Since the devastation of the 1999 İzmit earthquake, the country has attempted to reshape how it builds houses, regulates safety, and responds to shocks. New building codes introduced in 2007 and strengthened again in 2018 require structures to be designed for much higher seismic demands. Engineers now use performance-based standards, meaning buildings must not only stand but remain functional after major shaking. Critical infrastructure such as hospitals, airports, bridges has undergone extensive retrofitting, with base-isolated medical campuses in Istanbul and other cities intended to operate even during severe earthquakes. Municipalities run risk assessments, while universities refine seismic models. Public awareness campaigns encourage citizens to secure furniture, prepare earthquake kits and map their meeting points. These small steps across households and institutions form the quiet architecture of resilience.
To live in Turkey is to understand motion is part of the landscape. So the country moves forward, aware but unbroken, building safer structures, studying deep geology, and teaching each new generation how to live wisely on its restless ground. The earth will move again — that is certain. What remains within human hands is how ready we will be when it does.
