The Seismicity of the Marmara Sea Region of Turkey

The seismicity of the Marmara Sea area of Turkey is investigated by epicentral data from three sources: computer revisions of epicentres reported by the International Seismological Summary in the period 1923 to 1963, epicentres reported by the International Seismological Centre in 1964 to 1970, and micro-earthquake locations determined by a radio-linked seismometer network operating for two months in the summer of 1971 as part of a co-operative project between Kandilli Observatory and the Institute of Geological Sciences. The Marmara area is at a triple junction between the Turkish, Aegean, and Eurasian Plates in a complicated area of small block structures, and an understanding of the behaviour of the Marmara area is important in the interpretation of the tectonics of the whole region. The present paper delineates lines of seismicity, which suggest that the Anatolian Fault splits into three branches in the Marmara area diverting some of the east-west orientated stresses associated with the right-lateral Anatolian Fault southwards into Western Turkey and the Eastern Aegean.