The relationship of Microplate Velocity and Seismotectonic Variables

6. Examples from the Regions of Compression and Extension 2.5 3 3.5 4 4.5 5 5.5 10 0 10 1 10 2 Magnitude Cumulative Number b-value (w LS, M > 3.5): -0.671 +/- 0.08, a-value = 4.1116 b-value (max lik, M > 3): -0.887 +/- 0.11, a-value = 4.9569 80 85 90 95 0 50 100 150 200 250 300 350 Time in years Cumulative Number Region 19 Region 13 Aftershocks Cluster A Cluster B Cluster A Cluster B Background Aftershocks 25 o E 10' 20' 30' 40' 6' 12' 18' 38 o N 24.00' 30' 36' 42' 24 o E 30' 25 o E 30' 26 o E 30' 30' 45' 37 o N 15' 30'

7. Regional Variations of Complex Variables Examination of all log ( C r ) vs. log( r ) plots often reveals the presence of slope transitions in the 5 to 20 km range. In this study we also examine the behavior of D 2 and D 15 over the 2 to 10 km and 10 to 40 km range to determine if systematic differences exist in the behavior of the log ( C r ) vs. log( r ) plots at local and more regional scales. We then evaluate correlations between D at the 2 to 10 and 10 to 40 km scales with b and V and compare these correlations to those obtained between the full scale estimates of D with b and V. The t-test was used to evaluate the significance of differences between the different measures of fractal dimension.

8. Local Variations of Complex Variables

13. Earthquakes incorporated in the study included only those occurring between 1981 and 1998. Summary D q ( q = 2 through 15), b -value and V were computed in each of the 25 seismic subdivisions of the area. Scale transitions were common in the log C(r) versus log r correlation integrals. D varies with scale. Separate estimates of D 2 and D 15 were made over the 2 to 10 km and 10 to 40 km scales.

16. Negative Positive Afterthoughts on the Izmit Earthquake The correlation between D and b over the 1981 through 1998 time period reveals a continued increase in the positive correlation. The correlation of D 2 and D 15 with b -value, over the more recent 17 year time period, increases to 0.81 and 0.73 respectively.

17. Afterthoughts on the Izmit Earthquake Whether the tendency to positive correlation between D and b observed in the region of shear is indicative of increased contemporary seismic hazard is unknown, an analysis of the spatial variations of D , V , b -value, a -value, and T L currently in progress, may provide additional insights into seismic hazard assessment.

22. General Conclusions Interrelationships between complex seismotectonic variables ( b -value, the multifractal properties of epicenter distribution) and microplate velocity, differ with tectonic setting. Future studies of the spatial and temporal variations in these relationships with activity rates and local recurrence times may provide useful measures of seismic hazard.