Using offshore geodetic observations, we show that a segment of the North Anatolian Fault
in the central Sea of Marmara is locked and therefore accumulating strain. The strain
accumulation along this fault segment was previously extrapolated from onshore
observations or inferred from the absence of seismicity, but both methods could not
distinguish between fully locked or fully creeping fault behavior. A network of acoustic
transponders measured crustal deformation with mm-precision on the seafloor for 2.5 years …