Complex fault structure interactions of crustal shear zones revealed by seismic anisotropy: an example in the eastern betic cordillera (Spain)

Abstract

Terra Nova, 25, 57–64, 2013AbstractCharacterizing the interaction of a fault with its surroundings is vital to fully understand the tectonic processes involved and predict future behaviour. Regional and local stress orientations affect different fracture length scales, manifested by numerous associated fault, fracture and crack structures. We use seismic anisotropy to constrain the dominant orientation of aligned rupture planes of various length scales. In particular, we study shear‐wave splitting of regional seismic events in Trans‐Alboran Shear Zone (TASZ), south‐east Spain. The TASZ consists of three major left‐lateral strike‐slip faults and numerous secondary strike‐slip and thrust faults. The observed orientations for S‐waves vary from roughly N–S in the northern segment of TASZ, to E–W in the centre, to NNW–SSE and NNE–SSW in the south. We show that the strikes of fast polarizations reflect both structural and lithological differences, indicating complex interactions of principal and secondary faults within the crust to accommodating tectonic stresses.