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An international team of scientists has issued a new warning about the risk of a major earthquake affecting Istanbul, pointing to growing stress along a key section of the Main Marmara Fault beneath the Marmara Sea.
The study, led by Germany’s Helmholtz Center for Geosciences and published in the journal Science, found that seismic activity along the Main Marmara Fault has been progressing from west to east in recent years, increasing stress in the segment closest to Istanbul.
Authored by a 14-member research team that includes Turkish experts, the paper is titled “Progressive eastward rupture of the Main Marmara Fault toward Istanbul.”
The researchers said a series of moderate earthquakes that began in the western and central Marmara regions in 2011 and 2012, followed by the 2019 Silivri earthquake and the magnitude 6.2 quake on April 23, 2025, revealed a west-to-east rupture sequence along the fault.
According to the study, these events caused a “cascading stress transfer” toward the eastern sections of the fault, which have remained locked for a long period.
Scientists drew particular attention to a 15–20 kilometer-long (9.3-mile–12.4-mile) “silent segment” located offshore of the Avcilar district.
The study said this section has shown no recent seismic activity, raising concerns that it may be accumulating stress and could serve as a potential starting point for the next moderate or large earthquake.
Researchers also warned that a rupture or stress transfer in this area could trigger the Prince’s Islands segment to the east, which is described as fully locked and carrying a high level of accumulated stress.
The study stated that the Marmara Sea currently represents the area of highest seismic hazard in Europe and noted that stress along the fault is advancing toward Istanbul.
While the researchers said it is not possible to determine the timing of a potential earthquake, they emphasized that the risk remains and underlined the importance of detailed and continuous seismic monitoring in the region.
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