Palaeoseismicity of the Dinar fault, SW Turkey

The NW-SE-trending Dinar fault is an active normal fault upon which the 1 October 1995 earthquake (M = 6.1) occurred. The 1995 earthquake resulted in a c. 10-km-long surface rupture with the south side down-thrown by less than or equal to 50 cm. Investigations of two trench sites perpendicular to the 1995 rupture suggest at least two prior large earthquakes in historical times. Radiocarbon dates and historical records constrain the age of events between 1500 BC and AD 53, event 2 possibly coinciding with the earthquake that damaged Dinar (the ancient city of Apamea Kibotos) in c. 80 BC and event 1 around 1500 BC. Surface displacements determined for events 1 and 2, compared to the 1995 surface faulting, indicate that M > 6.8 earthquakes were associated with each rupture. Using the total displacement in trenches, a slip rate of about 1 mm yr(-1) can be estimated for the Dinar fault. Observations suggest that the return period for large earthquakes in the Dinar area is about 1500-2000 years.