North Anatolian Fault Zone, Northern Turkey: Empirical Equations and the Changes in Some Kinematic Characteristics

Mehmet UTKU

Monitoring the seismological development of a seismotectonic source is important to know the future behavior of the source concerned. The North Anatolian Fault Zone is one of the important seismotectonic sources in the world. The seismic moment-magnitude relations were computed according to the macroseismic and instrumental observations of 29 earthquakes with mb,S ³ 4.8 that occurred in the North Anatolian Fault Zone in the 1909-2000 period. The relations of seismic moment for this tectonic structure according to the surface wave magnitude and according to the fault area and the change in stress drop are the other seismological characteristics addressed in this study. Depending on the other parameters within the scope of the study, the threshold magnitude value and the mean slip rate for the visible fault on the ground surface are computed as 6.2 (Ms) and 2.2 cm/year, respectively. According to the 13958 earthquakes with M ³ 3.0 that occurred in the North Anatolian Fault Zone in the period between 11/24/0029 (29 A.D.) and 12/31/2014, the return period of a possible major earthquake to be generated by this zone is 250 years at the most. The a- and b- values which characterize the Zone are 4 and - 0.8 on an average, respectively. When the results in this study – obtained according to the 91-year data process and the 101-year evaluation process – are compared with the results known from the previous studies, the latest results appear more reliable both in terms of the length of the process considered and the quality of the data used. When the behavior of the seismotectonic source concerned is monitored depending on this, it is seen that some seismological characters remained stable, while some of them changed.