The 9 August 1912 Mürefte-Şarköy earthquake of the North Anatolian fault

The 9 August 1912 Mürefte earthquake (M s 7.3–7.4) occurred on the westernmost inland segment of the North Anatolian Fault (NAF) and is one of the most devastating events in the Balkan region during the early XX. century causing damage with maximum intensity IX-X MSK between the Sea of Marmara and the Bay of Saros. Historical reports of researchers of that time deliver extensive descriptions of the damage, post-seismic activity, ground deformation and tsunami caused by the tremor. Photos and illustrations of surface ruptures, landslides, liquefaction and lateral spreading depict the level, and distribution of primary- and secondary effects. This study combines available data (historical & modern) with new field analysis on the 1912 earthquake rupture. The detailed fault mapping reveals a simple continuous fault geometry along the 45-km-long inland section, which has completely ruptured with right-lateral displacements reaching up to 5.5 m. The earthquake magnitude and source duration imply a 135 ± 25 km rupture length. The slip distribution and the simple fault geometry support an offshore extension of the rupture towards both, the Sea of Marmara and the Bay of Saros. Considering the location, magnitude, and damage of the 13 September 1912 aftershock, the seismic sequence of M w > 5.7 earthquakes from 1975 to 2014, the major discontinuities of the NAF in the Bay of Saros and Sea of Marmara I suggest the 1912 earthquake sequence ruptured at least ~ 160 km-long section of the NAF from the Inner Saros basin to the Marmara Central Basin and left a 100-km-long seismic gap in the Sea of Marmara.