Earthquake Activity on the North Anatolian Fault Zone

Summary

The North Anatolian Fault Zone (NAFZ) of Turkey is a region of high seismicity. It is one of the seismically most active dextral fault systems of the world with a seismicity comparable with the San Andreas Fault in California and the Alpine Fault in New Zealand. The fault zone consists of a belt of shear weaknesses, showing characteristic features of Quaternary and more recent faulting.

Historical earthquake studies have shown that major earthquake sequences associated with faulting have occurred in the past. The last sequence of the fault zone began with the 1939 Erzincan Earthquake which was followed by several major earthquakes — a succession of events in time and space that has been reported nowhere else in the world. Statistics show that this sequence of destructive earthquakes caused a total loss of 50 000 human lives in the last forty years. This paper, in general, comprises the microearthquake studies around the western and eastern termini of the North Anatolian Fault. The past seismic activity for the western and eastern end is also studied to see the relation between the regional seismicity and recent tectonics.

In the west, the site investigation of the 1912 Earthquakeinthe Sarköy-Mürefte area of West Marmara indicated that an earthquake fault system extending in northeast-southwest direction was rejuvenated during the 1912 Earthquake. Later on,a micro-earthquake array was operated around the fault break of 1912, however, it revealed only low seismicity compared to the surrounding regions. This low earthquake activity has been evaluated in view of the recent tectonics of the region.

In the east of the North Anatolian Fault, in order to study the continuation of the North Anatolian Fault into East Anatolia, a microearthquake array is operated in the Lake Van region. Indications of active faulting were studied. The distribution of microearthquakes and structural lineaments were evaluated from the seismotectonic point of view.