**5.1 Humble dome anomaly, Houston, USA**

Gravity map was acquired over the Humble Dome, Houston, Texas. At the earth's surface, the measurements of this salt dome structure reveal a negative circular contoured Bouguer anomaly ([41], Figures 8–16). A Bouguer gravity profile is taken across the center of the Humble salt dome gravity map in Houston ([41], Figures 8–16). The Bouguer gravity profile was subject to a suitable separation method to remove the regional anomaly and obtain the residual gravity anomaly. The residual gravity anomaly profile of about 26 km long was digitized at an interval of 0.26 km (**Figure 10a**).

The R-parameter method procedures were applied to the residual gravity anomaly profile for the available shape parameters (**Table 6**). **Figure 10b–d** express the horizontal and vertical derivative anomalies, the amplitude analytic signal, and the R-parameter 2-D mosaic. It is found that the R-max value is 0.99 corresponds to a

#### **Figure 10.**

*The Humble dome anomaly, USA. (a) Gravity anomaly profile (red dotted lines) and the optimum-fitting model (solid black line), (b) Horizontal and vertical gradients of (a), (c) Analytic signal anomaly using the data of (b), and (d) 2-D mosaic of the R-parameter and the R-max value.*


**Table 6.**

*The Humble dome gravity anomaly, USA. The R-parameter calculated from different shape factors.*


## **Table 7.**

*The Humble dome gravity anomaly, USA. The Estimated parameters.*

spherical shape (*q* = 1.5). The best estimated model parameters are: *q* = 1.5, *<sup>z</sup>*<sup>o</sup> = 4.90 m, *<sup>x</sup>*<sup>o</sup> = 0 m, and *<sup>A</sup>* <sup>=</sup> 269.39 mGal m<sup>2</sup> .

The humble dome anomaly has been interpreted by several authors assuming a spherical source to decide the depth of the salt body. The obtained results agree well with those depths to the center that obtained by the published literatures of [36, 41, 47, 54–56] (**Table 7**).

By using a density contrast of 0.13 gm/cm<sup>3</sup> of [41], then the depth to the top of the spherical body of the humble dome obtained from the proposed technique is 315 m, which in excellent covenant with the true depth (305 m) confirmed by drilling and seismic information [41]. **Table 8** shows that several other researchers


#### **Table 8.**

*Depth to the top of the spherical body of the Humble dome anomaly, obtained by various approaches using an assumed density contrast (Δ*ρ*) of 0.13 gm/cm<sup>3</sup> [41].*

*Gravity Anomaly Interpretation Using the R-Parameter Imaging Technique over a Salt Dome DOI: http://dx.doi.org/10.5772/intechopen.105092*

utilizing the same density contrast found some differences in the depths to the top of this spherical source. The use of simple geometrically bodies in the constrained class of spheres, horizontal cylinders, and vertical cylinders is thus suggested as a way to accurately apply the current methodology to extract depth information. As a result, if exact density contrasts are used, the related radii can be correctly computed as well.
