A statistical study of the spatial distribution of the compression (P), null (B) and tension (T) axes around the fault causing the 2012 Ahar-Varzeghan earthquake, Qoshadagh mountains, NW Iran

Authors

1 1. PhD student of tectonics, Department of Geology, Faculty of Sciences, Ferdowsi university of Mashhad

2 Professor of tectonics, Department of Geology, Faculty of Sciences, Ferdowsi university of Mashhad.

3 M.Sc. of tectonic, Department of Geology, Faculty of Natural Sciences, University of Tabriz.

Abstract

In this study, the spatial distribution pattern of compression, null and tension axes was studied statistically around the Qoshadagh fault system by 26 collected earthquakes focal mechanism. The average orientation of compression, null and tension axes are 318/08, 082/74 and 221/12, respectively. Spatial distribution of these axes is cluster, girdle and girdle pattern respectively. Variations of orientation of the compression and tension axes are very low, in the way that the compression and tension axes are oriented NW-SE and NE-SW trending respectively. The variation range of sense of the earthquakes focal mechanism includes compressional, compressional- strike slip and strike-slip styles. The variations of the focal mechanism sense of earthquakes as well as the spatial orientation of compression, null and tension axes show that both of the compressional and strike-slip regimes are engaged in this area which can be considered as transpression deformation style in this area. This data set suggests NW-SE trending of maximum horizontal compressional stress for this area. This research shows that the study of sense of the focal mechanism of earthquakes and the spatial distribution pattern of compression, null and tension axes are important in understanding the deformation pattern of a region. 
 

Keywords

References

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Advanced Applied Geology
Volume 7, Issue 3
October 2017
Pages 76-82

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