An Assessment of the Spatial Variation of the Seismic b-Value across Iran

This paper presents a study of the spatial variation of Gutenberg-Richter seismic b-value over the Iranian region. For this purpose, based on the works carried out by investigators for tectonic and seismotectonic zoning of Iran, the region subdivided into five structural zones, namely, Alborz-Kopet Dagh zone, Azarbaijan zone, East-Central Iran zone, Makran zone, and Zagros zone. Then, the seismic b-value parameter has been computed for these five zones. The results obtained reveal that among these five mentioned zones, the Zagros zone shows the highest b-value (1.28 ± 0.03), and in contrast, the East-Central Iran zone shows the lowest value (0.84 ± 0.08). In addition, the contour map showing the spatial distribution of b-value over the region is presented. According to this map, some parts of the Iranian region such as the Central Iran and the Eastern Iran clearly act as resistant (rigid) blocks. In summary, the results of this research reveal that the study of the frequency-magnitude distribution of earthquakes can be reliably used as a tool to discover the seismic deformation patterns as well as different tectonic structures of the regions.