%0 Journal Article %T Gravity data interpretation using the algorithm fourth horizontal derivatives and s- curves method %J Journal of the Earth and Space Physics %I Institute of Geophysics, University of Tehran %Z 2538-371X %A Bahrami, Faezeh %A Ardestani, Vahid %D 2013 %\ 12/22/2013 %V 39 %N 4 %P 73-82 %! Gravity data interpretation using the algorithm fourth horizontal derivatives and s- curves method %K gravity anomalies %K Depth and shape estimation %K Numerical fourth horizontal derivative %K The s- curves method %R 10.22059/jesphys.2013.35981 %X The gravity method is one of the first geophysical techniques used in oil and gas exploration. An algorithm is developed for a fast quantitative interpretation of gravity data generated by geometrically simple but also the estimated depths and other model parameters of a buried structure. Following Abdelrahman et al (1989). The general gravity anomaly expression produced by a sphere, an infinite long horizontal cylinder and a semi- infinite vertical cylinder can be represented by the following equation                                                                                                           (1) where   and z is the depth of the body, xi is the horizontal position coordinate, σ is the density contrast, G is the universal gravitational constant and R is the radius and q is factor related to the shape of the buried structure and is equal to 0.5,1.0,and 1.5 for the semi- infinite vertical cylinder, horizontal cylinder and the sphere respectively. Consider nine observation point (xi  -4s),  (xi  -3s),  (xi  -2s),  (xi  -s),  (xi  ),  (xi  +s),  (xi  +2s),  (xi  +3s),  (xi  + 4s),  along the anomaly profile where s=1,2,3,M spacing units and is called the window length. Using equation (1) the simplest first numerical horizontal gravity gradient (dg/dx)                                                                        (2) the second horizontal derivative gravity anomaly is obtainedfrom equation (2) as                             (3) the third horizontal gradient is(3)                    (4) Similarly, the fourth horizontal gradient is (4) 5) Which yields;     Where                                                                                                              (7) Equation (5) can also be solved using a simple iteration method. Equations (5) can be used to determine the depth and the shape of a buried structure using the window curves method. The validity of the method is tested on synthetic data white and without random errors. The method was applied to a gravity anomaly from the Abade of Iran .The results shows that the s-curves intersect each other in a narrow region where  7.220