Gravite Anomalilerinden Gömülü Yapı Derinliğinin Belirlemesi için Bir Yaklaşım

Year 2023, Volume: 27 Issue: 1, 107 - 115, 25.04.2023

Mert Mete , Petek Sındırgı , Coşkun Sarı

https://doi.org/10.19113/sdufenbed.1163997

Abstract

Gravite anomalilerinden gömülü bir yapının derinliğini kestirmek için birçok yöntem geliştirilmiştir. Bu çalışmada, doğrusal bir bağıntı üretilerek normalleştirilmiş gravite değerlerinden yapı derinliğinin hesaplandığı bir yöntem tanıtılmıştır. Yöntem, gözlemlenen gravite verilerine uygulanabildiği gibi gravite anomali haritası üzerinde alınan profil verilerine de uygulanabilir. Özellikle, arazide ölçülen gravite verilerine kayan ortalama işleci uygulanması düzgünleştirilen verilerden küre, yatay ve düşey silindir gibi basit geometrik yapıların derinliklerinin
kestirilmesinde yöntem oldukça yararlıdır. Bu yöntem, sadece kalıntılara değil, aynı zamanda kısa profil uzunluğundaki Bouguer gravite verilerine de kolaylıkla uygulanabilir. Bu çalışmada, gürültüsüz ve çeşitli oranlarda gürültülü kuramsal modellere uygulanmıştır. Gürültü başarı oranını düşürse de tatmin edici sonuçlar elde edilmiştir. Ayrıca, yöntemin geçerliliğini sınamak amacıyla, farklı
araştırmacılar tarafından değerlendirilen Mobrun, Medford, Cuba ve Leona gibi dünyanın çeşitli alanlarında ölçülen gravite anomalilerinin literatürde yer alan değerlendirme sonuçları ile yöntem çözümleri karşılaştırılmıştır. Küre, yatay ve düşey silindir yapı modelleri için saptanan çözümlerin literatürde yer alan sonuçlarla uyumlu olduğu gözlenmiştir.

Keywords

Gravite, Kayan Ortalama, Küre, Yatay Silindir, Düşey Silindir

An Approach to Determine the Buried Structure Depth from Gravity Anomalies

Abstract

Many methods have been developed to estimate the depth of a buried structure from gravity anomalies. The method introduced in this study is to calculate the depth of structure from normalized gravity values by generating a linear equation. The method can be applied to the observed gravity data as well as the profile data taken on the gravity anomaly map. In particular, the application of the moving average operator to the gravity data measured in the field is very useful in estimating the depths of simple geometric structures such as spheres, horizontal
and vertical cylinders from the smoothed data. The method can be easily applied not only to residuals, but also to Bouguer gravity data with short profile lengths. In this study, the method was applied to noise-free data and noisy model data with varying degrees of noise ratio. In this study, it has been applied to the noise-free synthetic data and noisy data with varying degrees of noise rate. The results are satisfactory, although the added noise reduces the success rate. In addition, in order to test the validity of the method, the evaluation results of the gravity anomalies measured in various areas of the world such as Mobrun, Medford, Cuba and Leona, which were evaluated by different researchers, and the method solutions in the literature were
compared. It has been determined that the solutions obtained for the sphere, horizontal and vertical cylinder structure models are compatible with the results in the literature.

Keywords

Gravity, Moving Average, Sphere, Horizontal Cylinder, Vertical Cylinder

References

• [1] Roy, A. 1962. Ambiguity in Geophysical Interpretation. Geophysics, 27, 90-99.
• [2] Roy, L., Agarwal, N. P., Shaw, R. K. 2000. A New Concept in Euler Deconvolution of Isolated Gravity Anomalies. Geophysical Prospecting 48, 559-575.
• [3] Nettleton, L. L. 1976. Gravity and Magnetics in Oil Prospecting. McGraw-Hill Book Co., New York, NY, 462s.
• [4] Abdelrahman, E. M., EI-Araby, T. M. 1993. A Least-squares Minimization Approach to Depth Determination from Moving Average Residual Gravity Anomalies. Geophysics, 59, 1779-1784.
• [5] Sharma, B., Geldart, L. P. 1968. Analysis of Gravity Anomalies of Two-dimensional Faults using Fourier Transforms. Geophysical Prospecting, 16, 77-93.
• [6] Thompson, D. T. 1982. EULDPH-A New Technique for Making Computer-assisted Depth Estimates from Magnetic Data. Geophysics, 47, 31-37.
• [7] Mohan, N. L., Anandababu, L., Roa, S. 1986. Gravity Interpretation using Mellin Transform. Geophysics, 52, 114-122.
• [8] Gupta, O. P. 1983. A least-squares Approach to Depth Determination from Gravity Data. Geophysics, 48, 360-537.
• [9] Abdelrahman, E. M. 1990. Discııssion on a Least-squares Approach to Depth Determination from Gravity Data by O.P. Gupta. Geophysics, 55, 376-378.
• [10] Elawadi, E., Salem, A., Ushijima, K. 2001. Detection of Cavities from Gravity Data using a Neural Network. Exploration Geophysics, 32, 75-79.
• [11] Kaftan, I., Salk, M., Senol, Y. 2011. Evaluation of Gravity Data by using Artificial Neural Networks Case Study: Seferihisar Geothermal Area (Western Turkey). Journal of Applied Geophysics, 75 (4), 711-718.
• [12] Abdelrahman, E. M., EI-Araby, H. M., EI-Araby, T. M., Abo-Ezz, E. R., 2001. Three least-squares minimization approach to depth, shape, and amplitude coefficient determination from gravity data. Geophysics 66,1105-1109.
• [13] Grant, F. S., West, G. E. 1965. Interpretation Theory in Applied Geophysics. McGraw-Hill, Co., New York, NY, 140s.
• [14] Essa, K. S. 2012. A Fast Interpretation Method for Inverse Modelling of Residual Gravity Anomalies Caused by Simple Geometry. Journal of Geological Research, 2012, 1-10.
• [15] Robinson, E. S., Coruh, C. 1988. Basic Exploration Geophysics. Wiley, New York, NY, 562s.
• [16] Salem, A., Elawadi, E., S., Ushijima, K. 2003. Short note: Depth Determination from Residual Gravity Anomaly using a Simple Formula. Computer and Geosciences, 29, 801-804.
• [17] Biswas, A., Parija, M., Kumar, S. 2017. Global Nonlinear Optimization for the Interpretation of Source Parameters from Total Gradient of Gravity and Magnetic Anomalies Caused by Thin Dyke. Ann. Geophys., 60(2),1-17.
• [18] Davis, W. E., Jackson, W. H., Richter, D. H. 1957. Gravity Prospecting for Chromite Deposits in Camaguey Province, Cuba. Geophysics 22, 848-869.
• [19] Asfahani J., Tlas M. 2012. Fair Function Minimization for Direct Interpretation of Residual Gravity Anomaly Profiles due to Spheres and Cylinders. Pure and Applied Geophysics, 169, 157-165.
• [20] Mehanee S. A. 2014. Accurate and Efficient Regularized Inversion Approach for the Interpretation of Isolated Gravity Anomalies. Pure and Applied Geophysics ,171, 1897-1937.
• [21] Butler, D. K. 1984. Microgravimetric and Gravity Gradient Techniques for Detection of Subsurface Cavities. Geophysics, 49, 1084-1096.
• [22] Tlas, M., Asfahani, J., Karmeh, H. 2005, A Versatile Nonlinear Inversion to Interpret Gravity Anomaly Caused by a Simple Geometrical Structure. Pure and Applied Geophysics, 162, 2557–2571.
• [23] Biswas, A. 2015. Interpretation of Residual Gravity Anomaly Caused by a Simple Shaped Body using Very Fast Simulated Annealing Global Optimization. Geoscience Frontiers, 6(6), 875–893.
• [24] Abdelrahman, E. M., Bayoumi, A.I., Abdelhady, Y.E., Gobashy, M. M., El-Araby, H. M.,1989. Gravity interpretation using correlation factors between successive least-squares residual anomalies. Geophysics 54(12), 1614-1621. 1989.