Newly discovered, the Kayapa-Yenişehir cross-basin fault: As revealed by geological and geophysical studies along the southern branch of the North Anatolian Fault Zone, a possible source of the destructive 1855 Bursa earthquakes

Abstract

This study presents our geological and geophysical findings about a right-lateral cross-basin fault (Kayapa-Yenişehir Fault-KYF) formed in the composite Bursa-west, Bursa-east, and Yenişehir pull-apart basins on the southern branch of the North Anatolian Fault Zone around Bursa in southern Marmara. We examined the compatibility of our observations with various models proposed in the literature.The right-lateral KYF has slip rates of a maximum of 8.8 mm/year and a minimum of 3.0 mm/year, according to our GPS-based block modeling, and it seems to be related to the latest destructive 1850 and 1855 earthquakes around Bursa. The damage distribution of these earthquakes allows interpretation that only the western part of the KYF was ruptured. The slip rates obtained from the block modeling combined with 621 years since a 1400 CE earthquake suggest that 5.5 m of displacement has accumulated on the eastern 55 km of the KYF. These parameters suggest a magnitude 7.0 or greater earthquake is possible.