Fault geometry, segmentation and slip distribution associated with the 1939 Erzincan earthquake rupture along the North Anatolian fault, Turkey

Abstract

Abstract The intracontinental plate boundary, dextral North Anatolian fault (NAF), is well-known by the westward migration of the multi-segment large earthquake sequence during the twentieth century. The sequence, started by the 1939 Erzincan earthquake (M w 7.9), resulted in a 330 km-long multi-segment surface rupture. Slip magnitudes are relatively consistent on each segment, with averages per segment slip varying from 2.3 to 8.8 m, with maximum horizontal displacements up to 10.5 m. The variable slip along the 1939 surface rupture may be attributed to the differences in the strain accumulated on each segment between the penultimate event and the 1939 event, with higher slip measured in segments with greater elapse times. Deviation of the west end of the rupture propagation from the main strand of the NAF to the Ezinepazarı fault splay appears to be controlled not only by accumulated strain on that fault splay, but also by factors such as rupture direction, fault geometry and the level of stress transferred at the segment boundary. Analysis of rupture geometry and slip distribution in the 1939 earthquake has implications for source-fault characterization of similar multi-segment strike-slip faults.