On the drape and level flying aeromagnetic survey modes with terrain effects, and data reduction between arbitrary surfaces

In addition to the physical parameters such as magnetization intensity distribution, the volume and the shape of the magnetized material, directions of the magnetization and the ambient field, the distance between the observation surface and the causative sources significantly affects the shape and the amplitudes of the magnetic anomalies. Aeromagnetic surveys are performed using either a draped surface or a constant elevation plane above sea level. These surveys can easily reconnoiter large territories in a short time. However, the magnetic anomalies may be attenuated resulting in some losses in the data resolution based on the flight height of the survey. In this paper, these effects were investigated in a detailed manner through some synthetic anomalies generated from 2D and 3D hypothetical subsurface models. Besides, magnetic terrain effects were also examined in the synthetic simulations which were produced for different scenarios. Real aeromagnetic anomalies obtained using a drape flying survey mode over the rugged high topographic relief of the Mount Nemrut stratovolcano (Bitlis, eastern Turkey) and its close vicinity were also investigated. Numerical simulations show that although both data acquisition modes have some weak sides, the level flying mode is more advantageous than the drape flying mode in general. Better anomaly interpretation can be achieved by reducing the draped data set into the one observed over a horizontal plane or vice versa and comparing these two data sets. Lastly, a simple computational process which can be performed in the Fourier wavenumber domain is proposed for data reduction procedure.

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