Mathematical and Statistical Determination of Seismicity Index, Recurrence Interval and Seismic Risk of Shallow Earthquake Occurrence in Anatolian Fault in Turkey

Source abstract

This study investigates the seismicity index, recurrence interval, and seismic risk of shallow earthquakes along the Anatolian Fault in Turkey using the least squares regression technique. Earthquake data were obtained from the International Seismological Centre (ISC) catalogue, considering events with Mb ≥ 4.0 and focal depths of 0–40 km. A total of 1,008 earthquake events were analysed. The least squares method produced seismicity parameters of a = 6.787 and b = 0.98666, representing the level of seismic activity and the relative occurrence of small versus large earthquakes. These parameters were used to estimate annual occurrence rates, recurrence intervals, and occurrence probabilities for different earthquake magnitudes. Results indicate that seismicity along the Anatolian Fault is dominated by low- to moderate-magnitude earthquakes, while larger events occur less frequently. The seismicity index decreases with increasing magnitude, whereas recurrence intervals become longer, demonstrating an inverse relationship between earthquake size and frequency. Seismic risk increases with longer exposure periods but decreases for higher-magnitude events because of their lower recurrence rates. These findings enhance understanding of the seismic behaviour of the Anatolian Fault and provide valuable information for seismic hazard assessment, earthquake preparedness, resilient infrastructure design, and strategies to reduce the impacts of future earthquakes.