The historical tsunamis in the Marmara Sea were mainly caused by earthquakes and needed to be documented. Following 1999 Izmit earthquake occurred at the Eastern Marmara region, a complete inventory of active faults in the Marmara Sea region became much more stressed. To the west, the latest event is 09.08.1912, Sarkoy-Murefte Earthquake. It occurred on the active Ganos Fault zone and was one of the largest earthquakes in the Balkans. The eastern termination of the associated faulting is in the deep West Marmara Trough, westernmost of the successive basins forming the Marmara Sea. On the basis of recent multibeam bathymetry and seismic reflection data, estimated total length of the surface rupture is about 56 km. The historical data reviewed from library and archive documents, geological field surveys and offshore geophysical investigations have shown that the 1912 earthquake produced a tsunami. In addition a seabed dislocation, the source of 1912 tsunami can also be assigned to the sediment slumps appearing in the form of echelon landslide prisms along the southern slopes of the West Marmara Trough.