Shallow Crustal Structure in the DehDasht Region (SW Iran) from Ambient Seismic Noise Tomography

Zagros continental collision zone (S-SW Iran) is tectonically active and extends over 1800 km contained most part of hydrocarbon reservoirs worldwide. The DehDasht region is located in the southeast of the Dezful embayment in the Zagros fold-and-thrust belt. The existence of an evaporation layer with high velocity features is the main challenge to apply classical seismic exploration in this region. However, ambient seismic noise carries valuable information about the propagation path; hence it could be a useful tool for studying crustal structure in the DehDasht region. For this purpose, we used up to 9 months of continuous data recorded by 107 stations in the area with ~16 × ~24 km². All stations are equipped with broadband (120s) sensors recording at 100 sps. The standard ambient seismic noise processing was done as outlined by Bensen et al. (2007), and optimize empirical Green’s function (EGF) was retrieved based on the WRMS stacking method. Afterward, Rayleigh wave dispersion measurements were calculated using the FTAN approach in the period range of 0.1-5.0 s, then the inversion procedure was performed by the Fast-Marching Method with an inversion cell size of 2×2 km. Our group velocity tomographic maps show a high velocity anomaly in the Khaviz Mountain belt (west part of the study area) is generally linked to the older, consolidated bodies while two low velocity anomalies are related to the presence of fluids and or younger structures.