A Statistical Approach to Depth Determination from Gravity Gradients

Abstract

Correlation factors between successive least-squares gravity anomalies are recognized as useful tools for quantitative studies of geophysical data. In the present paper, an interpretive technique based on the correlation factors is formulated in the case of first horizontal and vertical derivatives of gravity due to two geometries: the sphere, and the horizontal cylinder. It is demonstrated that correlation values can be used to determine the depth to the centre of the buried structure. The second horizontal derivative of the gravity anomaly due to a thin faulted layer and the first horizontal derivative of the gravity anomaly due to a horizontal cylinder are found to be identical in shape. Hence the method designed for interpreting the gravity anomalies due to a horizontal cylinder can also be used to interpret the gravity anomalies due to a fault. The method is easy to apply, but may be automated if desired. The method is tested on a field example from the Gulf of Suez region, Egypt.