J. Eng. Technol. Sci., Vol. 50, No. 1, 2018, 127-139 127 Received December 7 th , 2017, Revised March 27 th , 2018, Accepted for publication March 29 th , 2018. Copyright ©2018 Published by ITB Journal Publisher, ISSN: 2337-5779, DOI: 10.5614/j.eng.technol.sci.2018.50.1.9 A Note on the Use of the Second Vertical Derivative (SVD) of Gravity Data with Reference to Indonesian Cases Prihadi Sumintadireja 1 , Darharta Dahrin 2 & Hendra Grandis 2 * 1 Faculty of Earth Science and Technology, Institut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132, Indonesia 2 Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132, Indonesia *E-mail: grandis@geoph.itb.ac.id Abstract. Gravity data analysis and interpretation are based, among others, on their spatial variation represented by horizontal and vertical gradients. The gradient or derivative of a gravity field can be calculated either in the spatial domain or the wave-number domain. Historically, the second vertical derivative (SVD) of gravity data can be used to delineate the boundaries of anomalous sources. This paper addresses inappropriate use of the SVD of gravity data, with reference to current practices in Indonesia. The SVD’s relative magnitude along a profile is widely used to define whether a density contrast and its dipping orientation correspond to a normal or reverse fault, which may be geologically incorrect. Furthermore, the SVD is calculated by approximation using the horizontal derivative, which may be erroneous especially with poorly distributed data and anomalous 3D sources. We exemplify our analysis with synthetic data and propose a more appropriate spectral-based analysis using field data. Keywords: anomaly enhancement; basin delineation; fault; gradient; potential field. 1 Introduction Potential field (gravity and magnetic) methods are used on a wide variety of scales, i.e. from basin delineation at a regional scale to prospect investigation at a very detailed scale. Spatial derivatives of potential field data are commonly analyzed for qualitative and semi-quantitative interpretation. Horizontal and vertical gradients are expected to enhance anomalous source boundaries from anomaly maps [1,2]. On the other hand, decaying characteristics of the anomaly may be used to infer the lateral position and depth of simple or elementary anomalous sources, as in Euler deconvolution or its variants [3,4]. The Fourier domain is often preferred for advanced processing of gravity and magnetic data, mostly because of speed and simplicity in operation, especially with the vast amounts of data acquired in recent years. However, with the advances of computational tools, grid-based data processing in the spatial domain can also be efficiently executed. The choice of the calculation technique