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Studia Geophysica et Geodaetica

, Volume 55, Issue 1, pp 175–190 | Cite as

Estimation of the normal geomagnetic field and geological interpretation of the normal field anomalies over middle-northern Croatia

  • Eugen VujićEmail author
  • Giuliana Verbanac
  • Stanislav Francisković-Bilinski
  • Vladis Vujnović
  • Antun Marki
Article

Abstract

Based on the ground survey of total-field magnetic data at 53 sites, which recorded a time-series over the interval 2003–2005, the core field + long wavelength lithospheric field over the middle-northern Croatia region was calculated. The area of the survey was 18900 km2, an average distance between the neighbouring sites being 12 km. The results were reduced to 2004.5 epoch. This “normal” total-field was estimated using the firstorder Taylor polynomial as a function of geographic coordinates, and the polynomial coefficients were calculated with three methods of adjustment: simple and weighted least squares fits and adjustment according to the most frequent value. The stability of the normal field was tested using the Monte Carlo-type test, by decreasing the input data set in each adjustment (up to 90%). All obtained field residuals (measured-“normal”) were mutually compared, as well as fit coefficients of the Taylor polynomials. The residual values indicate the presence of shorter-wavelength anomalies, specifically three major residual anomalies were found (−106 nT, 74 nT and 57 nT). The geostatistical analysis of the ground survey data and the normal field residuals (respectively), using the median absolute deviation method, was further conducted in order to evaluate the calculated anomalies. The geological situation around the anomalies derived by the median absolute deviation method, and around the normal field residual anomalies, is given. The correlation was found between higher value anomalies of the normal field residuals, and shallow volcanic rocks and oil field, respectively.

Keywords

ground total-field data normal geomagnetic field geological interpretation of geomagnetic anomalies 

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Copyright information

© Institute of Geophysics of the ASCR, v.v.i 2011

Authors and Affiliations

  • Eugen Vujić
    • 1
    Email author
  • Giuliana Verbanac
    • 1
  • Stanislav Francisković-Bilinski
    • 2
  • Vladis Vujnović
    • 1
  • Antun Marki
    • 1
  1. 1.Department of Geophysics, Faculty of SciencesUniversity of ZagrebZagrebCroatia
  2. 2.Institute “Ruđer Bošković”ZagrebCroatia

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