Slip Rate Estimation on the North Anatolian Fault Using Geomorphology and Paleoclimate Chronology: The Ganos Fault, Turkey

Abstract

Offset streams are well recorders of the long-term and short-term deformation along strike-slip faults. Two independent processes act during the formation of offset streams: (1) climatic processes that support stream formation; (2) successive fault displacement across the stream channel. Field investigations are conducted along the westernmost inland segment of the North Anatolian fault; the Ganos fault; 48 right-lateral stream offsets are documented ranging 8 to 575 m. The stream offsets show five distinct groups of comparable magnitude that can be explained as episodes of new stream incisions due to high precipitation periods. Paleoclimatic studies in the region reveal the timing of these periods. Using a Black Sea sea-level curve for the last 20 ka, five subsequent sea-level rise periods are determined at 4, 10.2, 12.5, 14.5, and 17.5 ka. They can be considered as climatic periods favorable for stream incisions in the Ganos area. Linking the five offset groups with precipitation periods provides an average 17.9 mm/year slip rate for the last 20.000 years and a variability of 17.7 mm/year, 17.7 mm/year, 17.9 mm/year, and 18.9 mm/year for the last 10.2 ka, 12.5 ka, 14.5 ka, and 17.5 ka, respectively. These results are comparable with values for the eastern parts of the NAF, ranging from 15 to 25 mm/year.