1887
Volume 49, Issue 1
  • E-ISSN: 1365-2478

Abstract

A high‐resolution method to image the horizontal boundaries of gravity and magnetic sources is presented (the enhanced horizontal derivative (EHD) method). The EHD is formed by taking the horizontal derivative of a sum of vertical derivatives of increasing order. The location of EHD maxima is used to outline the source boundaries. While for gravity anomalies the method can be applied immediately, magnetic anomalies should be previously reduced to the pole. We found that working on reduced‐to‐the‐pole magnetic anomalies leads to better results than those obtainable by working on magnetic anomalies in dipolar form, even when the magnetization direction parameters are not well estimated. This is confirmed also for other popular methods used to estimate the horizontal location of potential fields source boundaries.

The EHD method is highly flexible, and different conditions of signal‐to‐noise ratios and depths‐to‐source can be treated by an appropriate selection of the terms of the summation. A strategy to perform high‐order vertical derivatives is also suggested. This involves both frequency‐ and space‐domain transformations and gives more stable results than the usual Fourier method.

The high resolution of the EHD method is demonstrated on a number of synthetic gravity and magnetic fields due to isolated as well as to interfering deep‐seated prismatic sources. The resolving power of this method was tested also by comparing the results with those obtained by another high‐resolution method based on the analytic signal. The success of the EHD method in the definition of the source boundary is due to the fact that it conveys efficiently all the different boundary information contained in any single term of the sum.

Application to a magnetic data set of a volcanic area in southern Italy helped to define the probable boundaries of a calderic collapse, marked by a number of magmatic intrusions. Previous interpretations of gravity and magnetic fields suggested a subcircular shape for this caldera, the boundaries of which are imaged with better detail using the EHD method.

Loading

Article metrics loading...

/content/journals/10.1046/j.1365-2478.2001.00235.x
2001-12-21
2024-03-29
Loading full text...

Full text loading...

References

  1. AgarwalB.N.P. & ShawR.K.1996. Comment on: ‘An analytic signal approach to the interpretation of total field magnetic anomalies’ by Shuang Qin. Geophysical Prospecting44, 911–914.
    [Google Scholar]
  2. BarberiF., CassanoE., La TorreP. & SbranaA.1991. Structural evolution of Campi Flegrei caldera in light of volcanological and geophysical data. Journal of Volcanology and Geothermal Research48, 33–49.
    [Google Scholar]
  3. BlakelyR.J. & SimpsonR.W.1986. Approximating edges of source bodies from magnetic or gravity anomalies. Geophysics51, 1494–1498.
    [Google Scholar]
  4. CassanoE. & La TorreP.1987. Geophysics. In: Phlegrean Fields: Quaderni della Ricerca Scientific, Vol. 114 (eds M.Rosi and A.Sbrana ), pp. 103–131. Consiglio Nazionale delle Ricerche.
    [Google Scholar]
  5. CordellL. & GrauchV.J.S.1985. Mapping basement magnetization zones from aeromagnetic data in the San Juan basin, New Mexico. In: The Utility of Regional Gravity and Magnetic Anomaly Maps (ed. W.J.Hinze ), pp. 181–197. Society of Exploration Geophysicists.
    [Google Scholar]
  6. EvjenH.M.1936. The place of the vertical gradient in gravitational interpretations. Geophysics1, 127–136.
    [Google Scholar]
  7. FlorioG., FediM., CellaF. & RapollaA.1999. The Campanian Plain and Phlegrean Fields: structural setting from potential field data. Journal of Volcanology and Geothermal Research91, 361–379.DOI: 10.1016/s0377-0273(99)00044-x
    [Google Scholar]
  8. GibertD. & GaldeanoA.1985. A computer program to perform transformations of gravimetric and aeromagnetic surveys. Computers and Geosciences11, 553–588.
    [Google Scholar]
  9. GunnP.J.1975. Linear transformations of gravity and magnetic fields. Geophysical Prospecting23, 300–312.
    [Google Scholar]
  10. HsuS., CoppensD. & ShyuC.1998. Depth to magnetic source using the generalized analytic signal. Geophysics63, 1947–1957.
    [Google Scholar]
  11. HsuS., SibuetJ.C. & ShyuC.1996. High‐resolution detection of geologic boundaries from potential field anomalies: an enhanced analytic signal technique. Geophysics61, 373–386.
    [Google Scholar]
  12. KornG.A. & KornT.M.1968.Mathematical Handbook. McGraw‐Hill Book Co.
    [Google Scholar]
  13. LinpingH. & ZhiningG.1998. Discussion on ‘Magnetic interpretation using the 3‐D analytic signal’ by W.R. Roestet al.Geophysics63, 667–670.
    [Google Scholar]
  14. LinpingH., ZhiningG. & ChangliY.1997. Comment on: ‘An analytic signal approach to the interpretation of total field magnetic anomalies’ by Shuang Qin. Geophysical Prospecting45, 879–881.
    [Google Scholar]
  15. NabighianM.N.1974. Additional comments on the analytic signal of two dimensional magnetic bodies with polygonal cross‐section. Geophysics39, 85–92.
    [Google Scholar]
  16. NabighianM.N.1984. Toward a three‐dimensional automatic interpretation of potential field data via generalized Hilbert transforms: fundamental relations. Geophysics49, 780–786.
    [Google Scholar]
  17. OrsiG., De VitaS. & Di VitoM.1996. The restless, resurgent Campi Flegrei nested caldera (Italy): constraints on its evolution and configuration. Journal of Volcanology and Geothermal Research74, 179–214.DOI: 10.1016/s0377-0273(96)00063-7
    [Google Scholar]
  18. QinS.1994. An analytic signal approach to the interpretation of total field magnetic anomalies. Geophysical Prospecting42, 665–675.
    [Google Scholar]
  19. RavatD.1996. Analysis of the Euler method and its applicability in environmental magnetic investigations. Journal of Environmental and Engineering Geophysics1, 229–238.
    [Google Scholar]
  20. ReidA.B., AllsopJ.M., GranserH., MillettA.J. & SomertonI.W.1990. Magnetic interpretation in three dimensions using Euler deconvolution. Geophysics55, 80–91.
    [Google Scholar]
  21. RoestW.R., VerhoefJ. & PilkingtonM.1992. Magnetic interpretation using the 3‐D analytic signal. Geophysics57, 116–125.
    [Google Scholar]
  22. RosiM. & SbranaA., eds. 1987. Introduction, geological setting of the area, stratigraphy, description of mapped products, petrography, tectonics. In: Phlegrean Fields: Quaderni della Ricerca Scientifica, Vol. 114, pp. 9–93. Consiglio Nazionale delle Ricerche.
    [Google Scholar]
  23. ThompsonD.T.1982. EULDPH: a new technique for making computer‐assisted depth estimates from magnetic data. Geophysics47, 31–37.
    [Google Scholar]
  24. ThurstonJ.B. & SmithR.S.1997. Automatic conversion of magnetic data to depth, dip and susceptibility contrast using the SPI method. Geophysics62, 807–813.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.1046/j.1365-2478.2001.00235.x
Loading
/content/journals/10.1046/j.1365-2478.2001.00235.x
Loading

Data & Media loading...

  • Article Type: Research Article

Most Cited This Month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error