We applied a receiver function technique to investigate the crustal structure beneath the KTAS seismic station in the Salt Range area of Pakistan. The station was installed in 2010 and is a constituent station of the Pak-China Seismic Network of Pakistan Meteorological Department. The teleseismic broadband waveform data recorded by this seismic station were used for this research. We calculated receiver functions using the source equalization technique to obtain good receiver functions for three events. Then, we compared the observed receiver functions to synthetic receiver functions computed for the four crust models taken from the global crust model CRUST 2.0 to find significant differences.
Since in the study area, the Salt Range, there exist salt reservoirs (halite i.e. rock salt), and since such a halite layer is not included in these four models, we modified one of the four models so that the modified models have the shallowest layer with physical properties (density, and shear wave velocity etc.) with halite beds. Then, we calculated synthetic receiver functions for these modified models. Comparison between the synthetic and observed receiver functions suggested the existence of a possible halite layer.
We carried out inversion of the observed receiver functions for crust structure using genetic algorithm including a parameter range of a halite layer. Two selected teleseismic events were stacked for inversion. The obtained model contains a top layer whose physical property is consistent with halite, and the synthetic receiver function computed for this model explained the earlier part of the receiver functions. This result suggested the existence of halite in the study region. The depth of Moho was estimated to be about 55 km, which is consistent with previous studies.