TEMPORAL VARIATIONS IN THE FRACTAL PROPERTIES OF SEISMICITY IN THE NORTH ANATOLIAN FAULT ZONE BETWEEN 31-DEGREES-E AND 41-DEGREES-E

We investigate the nature of temporal variations in the statistical pr operties of seismicity associated with the North Anatolian Fault Zone between longitudes 31 degrees-41 degrees E during the instrumental per iod 1900-1992. Temporal variations in the seismic b value and the frac tal (correlation) dimension D-c of earthquake epicenters are examined for earthquakes of magnitude M(S) greater than or equal to 4.5, using sliding windows of 100 consecutive events. b varies temporally between 0.6 and 1.0, and D-c between 0.6 and 1.4, both representing significa nt fluctuations above the errors in measurement technique. A strong ne gative correlation (r = -0.85) is observed between b and D-c, consiste nt with previous observation of seismicity in Japan and southern Calif ornia. Major events early in this century (M(S) greater than or equal to 7) are associated with low b and high D-c, respectively consistent with greater stress intensity and greater spatial clustering of epicen ters-both implying a greater degree of stress concentration at this ti me.