Correlation of seismotectonic variables and GPS strain measurements in western Turkey

Abstract

Interrelationships between the multifractal properties of epicenter distribution (Dq), the Gutenberg‐Richter b value, and GPS‐derived strain (shear and dilatation) for the time period extending from 1981 to 1998 are examined in the eastern Mediterranean and western Turkey area. This analysis was conducted in three tectonic subdivisions corresponding to regions dominated by shear, extensional, and compressional deformation. The region of shear coincides with the Northern Anatolian Fault Zone (NAFZ); the region of extension, with the Aegean back arc region; and the region of compression, to the Aegean subduction zone between the African and Anatolian plates. The median b value in the region of extension is larger than those observed in the regions of shear and compression and suggests that large magnitude earthquakes are less probable in this region than along the NAFZ and Aegean subduction zone. A significant correlation is observed between D2 and D15 with dilatation over the 10–40 km range in the back arc region of extension. A marginal correlation between GPS‐derived strain and b value is observed only in the region of compression where it correlates negatively with shear and positively with dilatation. A significant positive correlation is observed between D and b along the NAFZ. A clear relationship between D and b does not exist in regions deformed by extension and compression. The relationship between D and b along the NAFZ may also be an indicator of increased seismic hazard since the positive relationship between D and b is a recent characteristic of the NAFZ observed only in the 20‐year period preceding the Izmit earthquake.