On the effectiveness of directional derivative based filters on gravity anomalies for source edge approximation: synthetic simulations and a case study from the Aegean graben system (western Anatolia, Turkey)

Abstract

Approximating the locations and lateral boundaries of anomalous bodies (i.e. geological structures or contacts) is an important task in the interpretation of gravity field data. Edge-approximating algorithms based on the computation of directional derivatives are widely used for enhancing the gravity anomalies of the source bodies. These algorithms effectively aid geological mapping and interpretation by locating abrupt lateral changes in density, and may also bring out subtle details in the data without specifying any prior information about the nature and type of the sources. Therefore, some model parameters of source bodies may be estimated in this way, which may guide the inverse modelling procedure. In this paper we aim to review the effectiveness of the commonly used edge-approximating algorithms such as vertical derivative, total horizontal derivative, analytic signal, profile curvature, tilt angle and theta map in terms of their accuracy on the determination of locations and lateral boundaries of source bodies. These detections were performed on both noise-free and noisy synthetic gravity data. Additionally, a real gravity data set from a well-known geological setting, the Aegean graben system (western Turkey), was considered and the derived anomaly maps were compared with known mapped geology.