Geological Implications of Crustal Structure in Central of Iraq Using the Receiver Function Technique

Abstract

The current study aims to investigate the geological implications of the crustal structure beneath two seismic stations in central of Iraq. The inversion of the teleseismic P-wave receiver functions (RFs) was employed to determine the structure of the crust under Anbar (ANB1) and Karbala (KAR2) broadband seismic stations. Some of the computer programs in seismology (CPS) were used to analyze the receiver functions of seventeen teleseismic earthquakes. Results of inversion show that the crustal thickness (Moho depth) beneath the study area ranges from 44 to 46km, with an average value of 45km. The sedimentary cover thickness (basement depth) in the study area is about 12km. In general, the obtained sedimentary cover and crustal thicknesses are consistent with the results of some previous studies in the Mesopotamian plain. As well as the inversion results show that the crustal velocity model beneath the study area has four distinct layers; the first at 6km with Vs of 1.76 km/s, the second one at 12km with Vs of 2.84, the third one at 33km with Vs of 3.50 km/s, and the fourth one at 45km with Vs of 4.15km/s. The obtained velocity model may be employed to locate and relocate the local and teleseismic earthquakes and in moment tensor solutions. The crustal thickness, Vp/Vs, and Poisson's ratios are important parameters that are used to understand the crustal structure, composition, deformation, and evolution. As mentioned above, the average crustal thickness of the study area is 45 km. The obtained crustal thickness value is consistent with that reported in the platform regions. The crustal Vp/Vs of the study area equals 1.79. This value is typical for the platform region and andesitic rocks. An intermediate value (0.27) of the crustal Poisson's ratio was reported. It indicates that there is little difference in the felsic and mafic contents of the crust.