GNGTS 2013 - Atti del 32° Convegno Nazionale

related to the upward continued field of the vertical derivative of the data d , to a distance equal to the opposite of the layer depth: z =- h i . So the resulting signal is a combination of a vertical derivative filter, which amplifies the high-frequency components of the data, and an upward continuation, which is, on the contrary, a low pass filter for definition. This feature is interesting and has been investigated by many authors who tested the coupling of upward continuation and field derivatives. The benefits of using the vertical derivative were documented by Fedi and Florio (2001): they showed that when the gravity fields of several sources interfere, it is more accurate to use the vertical derivative of the field rather than the field itself to determine the location of contacts of the sources. This is in part due to the vertical derivative being able to isolate the gravity effects of individual sources better than the Bouguer anomaly. Hence, the signatures of small-scale features that are not easily identified in Bouguer anomaly maps can be identified and mapped using the vertical derivative response. So from the horizontal derivative magnitude of the VUC response, it is possible to outline and differentiate vertical and dipping geological contacts as well as the direction of the dip; and also to separate multiple anomalies. The higher frequencies will be enhanced at the expense of lower frequencies; however, if the data contain noise or small errors, the coupled filter already inbuilt in Cribb’s relationship 147 GNGTS 2013 S essione 3.2