Detecting, delineating and modeling the connected solution cavities in a dam site via microgravity data

Abstract

Microgravity data is used in a mild topography with relatively rough terrain surrounding area to detect, delineate and model the cavities and their probable connections. After standard gravity corrections the Bouguer gravity anomalies are computed. The linear trend of anomalies are detected by using the total horizontal gradient method. This trend of linear anomalies can be caused by connected solution cavities. These cavities are due to the solution of salt deposits (Halite). Using the polynomial fitting approach, the residual gravity anomalies are computed. Several relative negative anomalies are distinguishable in the residual maps and mostly along the assumed linear trends. Rough estimations of the minimum and the maximum depths of these anomalies are provided by Euler de-convolution and upward continuation methods. These anomalies are modeled by the three dimensional inversion algorithms. The computed depths of the main negative anomalies are compared to the depths of the cavities observed in the bore-holes drilling before and during the microgravity survey.