Combination of seismic and an isostatic crustal thickness models using Butterworth filter in a spectral approach

In this study, using Butterworth filter a combined crustal thickness model based on seismic and isostatic-gravimetric models is presented in a spectral domain. Vening Meinesz–Moritz isostatic model and a seismic model which obtained from sparse seismic data are two models used in this study. The filter used helps to join two models without any jump in the overlap degree in the spectral domain. The main motivations of this study are (a) presenting a higher resolution for the crustal thickness and (b) removing non-isostatic effects from the isostatic model. The result obtained from the combined model is a synthetic Earth crustal model up to degree 180 (equivalent resolution 1° × 1°). In spite of the differences in the some parts of the Earth between the seismic and isostatic-gravimetric models, the test computations show a satisfactory agreement between the results provided. Numerical results show that this method of combination agrees with the seismic crustal thickness (about 2.0 km rms difference).

► Combination of a low resolution seismic crustal thickness model with an isostatic one. ► Reducing disturbing signals from the gravity data in the isostatic one. ► Filling the seismic crustal data gaps in areas which the data are poor. ► Study a higher resolution of the Earth crustal model based on the combination various data.