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North Anatolian Fault (NAF) is one from the most important strike-slip fault zones in the world and located among regions in the highest seismic activity. The NAFZ observed very large earthquakes from the past to present. The aim of this study; the important parameters of Gutenberg-Richter relationship (a and b values) estimated and this parameters taking into account, earthquakes were examined in the between years 1900-2015 for 10 different seismic source regions in the NAFZ. After that estimated occurrence probabilities and return periods of occurring earthquakes in fault zone in the next years, and is being assessed with Poisson method the earthquake hazard of the NAFZ. The 10 different seismic source regions are determined the relationships between the cumulative number-magnitude which estimated a and b parameters with the equation of LogN=a-bM in the Gutenberg-Richter. A homogenous earthquake catalog for MS magnitude which is equal or larger than 4.0 is used for the time period between 1900 and 2015. The database of catalog used in the study has been created from International Seismological Center (ISC) and Boğazici University Kandilli observation and earthquake research institute (KOERI). The earthquake data were obtained until from 1900 to 1974 from KOERI and ISC until from 1974 to 2015 from KOERI. The probabilities of the earthquake occurring are estimated for the next 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 years in the 10 different seismic source regions. The highest earthquake occur probabilities in 10 different seismic source regions in the next years estimated that the region Tokat-Erzincan (Region 9) 99% with an earthquake occur probability for magnitude 6.5 which the return period 24.7 year, 92% with an earthquake occur probability for magnitude 7 which the return period 39.1 year, 80% with an earthquake occur probability for magnitude 7.5 which the return period 62.1 year, 64% with an earthquake occur probability for magnitude 8 which the return period 98.5 year. For the Marmara Region (Region 2) in the next 100 year estimated that 89% with an earthquake occur probability for magnitude 6 which the return period 44.9 year, 45% with an earthquake occur probability for magnitude 6.5 which the return period 87 year, 45% with an earthquake occur probability for magnitude 7 which the return period 168.6 year.

The Bayesian method is used to evaluate earthquake hazard parameters of maximum regional magnitude (M max ), b value, and seismic activity rate or intensity (k) and their uncertainties for the 15 different source regions in Western Anatolia. A compiled earthquake catalog that is homogenous for M s C 4 was completed during the period from 1900 to 2013. The computed M max values are between 6.00 and 8.06. Low values are found in the northern part of Western Anatolia, whereas high values are observed in the southern part of Western Anatolia, related to the Aegean subduction zone. The largest value is computed in region 10, comprising the Aegean Islands. The quantiles of functions of distributions of true and apparent magnitude on a given time interval [0,T] are evaluated. The quantiles of functions of distributions of apparent and true magnitudes for future time intervals of 5, 10, 20, 50, and 100 years are calculated in all seismogenic source regions for confidence limits of probability levels of 50, 70, and 90 %. According to the computed earthquake hazard parameters, the requirement leads to the earthquake estimation of the parameters referred to as the most seismically active regions of Western Anatolia. The Aegean Islands, which have the highest earthquake magnitude (7.65) in the next 100 years with a 90 % probability level, is the most dangerous region compared to other regions. The results found in this study can be used in probabilistic seismic hazard studies of Western Anatolia.

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