GEOLOGICAL EVIDENCE FOR THE LAST 2 FAULTING EVENTS ON THE NORTH ANATOLIAN FAULT ZONE IN THE MUDURNU VALLEY, WESTERN TURKEY

Recurrence intervals of large earthquakes produced by slip on the North Anatolian fault zone have been inferred mainly from historical records, and included much ambiguity. It is therefore important to date individual earthquakes using geological and geomorphological methods. We excavated an exploratory trench across the surface rupture zone associated with the Mudurnu Valley, western Turkey, earthquake of July 22, 1967, and revealed evidence for the last two faulting events including the 1967 earthquake. On the basis of the radiocarbon dates of sediments in the trench, we estimate most conservatively that the penultimate event occurred after 1480 A.D., but believe it likely that the event occurred shortly after 1650 (+/- 20) A.D. The penultimate event is likely to be correlated with the Anatolian earthquake of August 17, 1668, which caused severe damage along the North Anatolian fault zone for about 600 km from Bolu to Erzincan.