Marmara Sea fault movement reveals new earthquake data for Istanbul

New underwater acoustic measurements presented at EGU 2026 reveal that a fault segment west of the Kumburgaz Basin in the Marmara Sea is experiencing a slow creep of approximately 15 millimeters per year. This movement suggests the fault, previously thought to be locked, is slowly shifting.

Professor Osman Bektaş noted that an 8-kilometer-thick layer of soft sediment may be damping the movement, meaning the actual speed of the fault at greater depths could be higher than the 15 millimeters measured at the surface.

This slow movement might release some of the accumulated seismic moment, potentially reducing the magnitude of a future earthquake in the region. However, experts emphasize that a potential earthquake could still reach a magnitude of 6.0 or higher.