Seismotectonic Variables in Japan, Turkey and Canada

1. Ali O. Oncel Earth Science Department of KFUPM Seismological studies: evaluating linkages between seismotectonic variables in Japan, Turkey and Canada

4. If pattern has fractal properties then N = Cr -D N :the number of occupied boxes r: the length of the box (r). Fault Statistics

5. Active Fault Analysis in Japan

6. Seismicity Analysis in Japan

7. Correlation between faulting and seismicity

8. Negative Correlations : Stress suddenly released of larger magnitude seismicity on interconnected faults of larger total surface Positive Correlations: Stress is gradually released by lower magnitude seismicity on smaller fault strands. Tohoku Events: July 26 event (M=6.2) were located in a positive correlation (Area III) noted to be anomalously quiescent. Correlations of seismotectonic variables 5.00 to 6.00 6.00 to 7.00 1998-2003 M=6.2 2003.07.26 M=5.5 2003.07.26

9. displacement rate Almost 1000 stations in Japanese Islands daily measurement of location with accuracy of 1[cm] GPS Earth Observation Network (GEONET)

10. Aftershocks of July 26, 2003 (M w =6.0) GPS-local stations

12. stress rate tensor computed by using Hooke’s law from the computed strain rates for elastic materials. Maximum Shear Stress + * Mean Stress Rate Disturbing Stress Rate= Friction of coefficient ( =0.8) Lame’s Constants ≈ 30 GPa [Fowler, 1990] Strain rates

13. Disturbing stress changes and asperity

14. Contour maps of GPS derived shear and dilatation are shown in the maps above (middle and right maps, respectively). GPS strains were derived by Kahle et al. (2000) from GPS velocity data presented by McCloskey et al. (2000) for the western Turkey and eastern Mediterranean area examined in this paper. Average shear and dilatation in each seismic zone were estimated by averaging contour values of shear and dilatation observed on the regular grid of points highlighted in the map above. GPS control points are shown along with events of magnitude M>3.0 recorded between 1981 and 1998. The 25 seismic zones into which the area was subdivided for analysis and comparison are also outlined. Geodetical strain and earthquake hazard: Example from western Turkey

15. The study area was divided into three regional tectonic subdivisions consisting of a region of shear in the north associated with the Northern Anatolian Fault Zone (NAFZ), a region dominated by extension in the back-arc region of central Turkey, and a region of compression along the Aegean subduction zone. Seismotectonic parameters (D q and b) and geodetic strains (shear and dilatation) are shown in the table at right for each of the 25 seismic zones. Local Variations of Complex Variables

16. Median/mean values of multifractal correlation dimensions D 2 and D 15 are tabulated for the full range, 2 to 10km range and 10 to 40 km range for each tectonic subdivision of the study area (shear, extension, and compression). The median/mean values of b, shear, and dilatation are also listed for each tectonic region. Over the full range : D 2 measured in the region of compression is statistically greater than D 2 in the regions of extension and shear. D 15 is less than D 2 in all cases . Over the 2-10 km scale : Statistically significant differences between regions are not observed. Over the 10-40km scale : The larger value of D in the region of compression suggests that differences observed over the full range are primarily associated with variations occurring at larger 10-40km scales . Regional comparison between seismicity and GPS strain

17. The correlation coefficient, r = 0.81 The probability (p) that the slope of the regression line could actually be zero is 0.026 in this case. Cross-plot of b values and D 2 from the Northern Anatolian Fault Zone

19. Afterthoughts on the Izmit Earthquake Increased b and decreased D C suggest that the rise in the level of low magnitude seismicity and high intensity clustering along the western portion of NAFZ did not completely release stress transferred into this segment of the fault zone ( Oncel et al., 1995, Non.Lineer.Geophysics; Oncel and Wilson, 2001, BSSA ). This combination of factors - westward migration along with increased levels of low magnitude seismicity and higher intensity seismic clustering - are indicators of increased seismic risk in the area.

22. Coulomb Stress Modelling Illustration of the Coulomb stress change (King, 1994). The panels show a map view of a vertical strike-slip fault embedded in an elastic half-space, with imposed slip that tapers toward the fault ends. Stress changes are depicted by graded colors; green represents no change in stress. (A) Graphical representation of equation 8 of King et al (1994), a “specified fault” calculation. (B) Graphical presentation of equation 13 of King et al., (1994), for optimally-oriented strike-slip “opt strike-slip” faults.

23. Coulomb stress and aftershocks: Example from western Canada