Earthquakes in Istanbul: The Overdue Marmara Mega-Quake

Istanbul faces a very high earthquake risk and is widely regarded as one of the most dangerous large cities in Europe for seismic hazard. The city lies just north of the North Anatolian Fault, a major fracture where the Anatolian plate slides westward past the Eurasian plate, running through the Sea of Marmara only a short distance from the metropolis. Over the past century, ruptures along this fault have marched steadily westward toward Istanbul, and seismologists warn that the section beneath the Marmara Sea is now locked, storing energy for a large earthquake. Many scientists estimate a high probability of a magnitude 7 or greater quake striking near the city within the coming decades.

The most sobering recent precedent is the 1999 Izmit earthquake, a magnitude 7.6 rupture on the North Anatolian Fault about 90 kilometers east of Istanbul, which killed more than 17,000 people and destroyed tens of thousands of buildings across the industrial heartland. Istanbul itself has a long history of destructive earthquakes stretching back to Byzantine and Ottoman times, including a devastating quake in 1509 remembered as the "Lesser Judgment Day." With a population well over 15 million and large areas of older, poorly reinforced housing, authorities have launched urban transformation and retrofitting programs, but the combination of an overdue fault and dense construction makes preparedness essential for everyone in the city.