Skip to main content


Geomagnetic depth sounding in the Northern Apennines (Italy)

Article metrics

  • 327 Accesses

  • 13 Citations


A Geomagnetic Depth Sounding (GDS) survey covering the Northern Apennines of Italy has been carried out in the period 1992–94. Induction arrows maps and hypothetical event Fourier maps were constructed to obtain an electromagnetic imaging of this area. Since the two dimensional (2-D) character comes out from those maps for periods greater than 32 minutes, a 2-D inverse modeling was carried out. The model responses show that a deep conductive layer (>5000 S) underlies the Apennine chain at about 20 km depth. The transition between the Adriatic and the Tyrrhenian domains is marked by a rather sharp vertical offset in this conducting layer. In the northwest sector of the studied area an anomalous high conductivity behavior is superimposed on the regional trend, which corresponds to the geothermal field of Larderello-Travale.


  1. Amato, A., B. Alessandrini, and G. B. Cimini, Teleseismic wave tomography of Italy, in Seismic Tomography. Theory and Practice, edited by H. M. Iyer and K. Hirahara, pp. 361–396, Chapman & Hall, Cambridge, 1993.

  2. Anelli, L., M. Gorza, M. Pieri, and M. Riva, Subsurface well data in the northern Apennines (Italy), Mem. Soc. Geol. It., 48, 461–471, 1994.

  3. Armadillo, E., E. Bozzo, and M. Gambetta, Tecniche di analisi statistiche applicate ai dati magnetovariazionali per lo studio di strutture di conducibilità litosferiche, Proceeding 13th GNGTS Meeting, Rome, 143–150, 1995.

  4. Arora, B. R., A. Rigoti, I. Vitorello, A. L. Padilha, N. B. Trivedi, and F. H. Chamalaun, Magnetometer study array in North-Northeast Brazil: conductivity image building and functional Induction modes, Pageoph, 152, 349–375, 1998.

  5. Babuska, V. and J. Plomerovà, Tomographic studies of the upper mantle beneath Italian region, Terra Nova, 2, 569–576, 1990.

  6. Bailey, R. C., G. D. Edwards, G. D. Garland, R. Kurtz, and D. Pitcher, Electrical conductivity studies over a tectonically active area in Eastern Canada, J. Geomag. Geoelectr., 26, 125–146, 1974.

  7. Bally, A. W., L. Burbi, C. Cooper, and R. Ghelardoni, Balanced sections and seismic reflection profiles across the central Apennines, Mem. Soc. Geol. It., 35, 257–310, 1986.

  8. Banks, R. J. and D. Beamish, Local and regional induction in the British Isles, Geophys. J. R. astr. Soc., 79, 539–553, 1984.

  9. Barchi, M., G. Minelli, and G. Pialli, The CROP 03 profile: a synthesis of results on deep structures of the northern Apennines, Mem. Soc. Geol. It., 52, 383–400, 1998.

  10. Batini, F., G. Bertini, G. Giannelli, E. Pandelli, and M. Puxeddu, Deep structure of the Larderello field: contribution from recent geophysical and geological data, Mem. Soc. Geol. It., 5, 219–235, 1983.

  11. Cameli, G. M., I. Dini, and D. Liotta, Brittle/ductile boundary from seismic reflection lines of southern Tuscany (Northern Apennines, Italy), Mem. Soc. Geol. It., 52, 153–162, 1998.

  12. Cassinis, R., G. Pialli, M. Broggi, and M. Prosperi, Dati gravimetrici a grande scala lungo la fascia del profilo: interrogativi sull’assetto della crosta e del mantello, in Studi preliminari all’acquisizione dati del profilo CROP 03 Punta Ala — Gabicce, edited by G. Pialli, M. Barchi, and M. Menichetti, St. Geol. Cam., University of Camerino, Camerino, vol. I1, 41–48, 1991 (in Italian).

  13. Cataldi, R., F. Mongelli, P. Squarci, L. Taffi, G. Zito, and C. Calore, Geothermal ranking of Italian territory, Geothermics, 24(1), 115–129, 1995.

  14. Cerv, V. and J. Pek, Numerical solution of the two-dimensional inverse geomagnetic problem, Studia Geophys. Geod., 25, 69–80, 1981.

  15. Channell, J. E. T. and J. C. Mareschal, Delamination and asymmetric lithospheric thickening in the development of the Tyrrhenian Rift, in Alpine Tectonics, Geol. Soc. Spec. Publ., 45, 285–302, 1989.

  16. Consiglio Nazionale delle Ricerche, Structural model of Italy, scale 1:500,000, Progetto Finalizzato Geodinamica, Roma, 1991.

  17. De Groot-Hedlin, C. and C. G. Constable, Occam’s inversion to generate smooth, two dimensional models from magnetotelluric data, Geophysics, 55, 1613–1624, 1990.

  18. Edwards, R. N., R. C. Bailey, and G. D. Garland, Conductivity anomalies: lower crust or asthenophere?, Phys. Earth Planet. Inter., 25, 263–272, 1981.

  19. Egbert, G. D. and J. R. Booker, Multivariate analysis of geomagnetic array data. 1 The response space, J. Geophys. Res., 94(B10), 14227–14247, 1989.

  20. Egbert, G. D. and J. R. Booker, Robust estimation of geomagnetic transfer functions, Geophys. J. R. astr. Soc, 87, 173–194, 1986.

  21. ELEKTB Group, KTB and the electrical conductivity of the crust, J. Geophys. Res., 102, 18289–18305, 1997.

  22. Everett, J. E. and R. D. Hyndman, Geomagnetic variation and electrical conductivity structure in Southwestern Australia, Phys. Earth Planet. Inter., 1, 23–34, 1967.

  23. Federico, C. and C. Pauselli, Thermal evolution of the Northern Apennines (Italy), Mem. Soc. Geol. It., 52, 267–274, 1998.

  24. Gough, D. I., Magnetometer array studies, Earth structures and tectonic process, Rev. Geophys., 27, 141–157, 1989.

  25. Gough, D. I., Electromagnetic exploration for fluids in the Earth’s crust, Earth Sci. Rev., 32, 3–18, 1992.

  26. Hjelth, S. E. and T. Korja, Lithospheric and upper-mantle structures, results of electromagnetic sounding in Europe, Phys. Earth Planet. Inter, 79, 137–177, 1993.

  27. Hyndman, R. D. and P. M. Shearer, Water in the lower continental crust: modelling magnetotelluric and seismic reflection results, Geophys. J. Inter, 98, 343–365, 1989.

  28. Hyndman, R. D., L. L. Vanyan, G. Marquis, and L. K. Law, The origin of electrically conductive lower continental crust: saline water or graphite?, Phys. Earth Planet. Inter, 81, 325–344, 1993.

  29. Jolivet, L., C. Faccenna, B. Goffe, M. Mattei, F. Rossetti, C. Brunet, F. Storti, R. Funiciello, J. P. Cadet, N. d’Agostino, and T. Parra, Midcrustal shear zones in postorogenic extension: Example from the northern Tyrrhenian Sea, J. Geophys. Res., 103, 12123–12160, 1998.

  30. Jones, A. G., Electrical conductivity of the continental lower crust, in Continental Lower Crust, edited by D. M. Fountain, R. I. Arculus, and R. W. Kay, pp. 81–143, Elsevier, Amsterdam, 1992.

  31. Lavecchia, G., The Tyrrhenian-Apennines system: structural setting and seismotectogenesis, Tectonophys., 147, 263–296, 1988.

  32. Lilley, F. E. and B. R. Arora, The sign convention for quadrature Parkinson arrows in Geomagnetic induction Studies, Rev. Geophys. Space Phys., 20, 513–518, 1982.

  33. Losito, G. and M. Muschietti, Is the illite group the cause of high electrical conductivity in certain lithospheric areas?, Ann. Geofis., 41(3), 369–381, 1998.

  34. Lucente, F. P., C. Chiarabba, G. B. Cimini, and D. Giardini, Tomographic constraints on the geodynamic evolution of the Italian region, J. Geophys. Res., 104, 20307–20327, 1999.

  35. Marquis, G. and R. D. Hyndman, Geophysical support for aqueous fluids in the deep crust: seismic and electrical relationships, Geophys. J. Int., 110, 91–105, 1992.

  36. Mele, G., A. Rovelli, D. Seber, and M. Barazangi, Shear wave attenuation in the lithosphere beneath Italy and surrounding regions: Tectonic implications, J. Geophys. Res., 102, 11863–11875, 1997.

  37. Molina, F., E. Armando, R. Balia, O. Batteli, E. Bozzo, G. Budetta, G. Caneva, M. Ciminale, N. De Florentiis, A. De Santis, G. Dominici, M. Donnaloia, A. Elena, V. Iliceto, R. Lanza, M. Loddo, A. Meloni, E. Pinna, G. Santarato, and R. Zambrano, Geomagnetic survey of Italy at 1979.0 repeat station network and magnetic maps, Internal report ING publication 554, Rome, pp. 43, 1994.

  38. Mongelli, F., G. Zito, N. Ciaranfi, and P. Pieri, Interpretation of heat flow density of the Apennine chain, Italy, Tectonophys., 164, 267–280, 1989.

  39. Mongelli, F., F. Palumbo, M. Puxeddu, I. M. Villa, and G. Zito, Interpretation of the geothermal anomaly of Larderello, Italy, Mem. Soc. Geol. It., 52, 305–318, 1998.

  40. Parkinson, W. D., The analysis of single site induction data, Phys. Earth Planet. Inter., 53, 360–364, 1989.

  41. Parkinson, W. D. and F. W. Jones, The geomagnetic coast effect, Rev. Geophys. Space Phys., 17, 1999–2015, 1979.

  42. Pasquale, V., M. Verdoja, P. Chozzi, and P. Augliera, Dependence of the seismotectonic regime on the thermal state in the Northern Italian Apennines, Tectonophys., 217, 31–41, 1993.

  43. Pasquale, V., M. Verdoja, P. Chozzi, and G. Ranalli, Rheology and seismotectonic regime in the northern central Mediterranean, Tectonophys., 270, 239–257, 1997.

  44. Pek, J., Numerical inversion of 2D MT data by models with variable geometry, Phys. Earth Planet. Inter., 45, 193–203, 1987.

  45. Pialli, G., M. Barchi, and G. Minelli, Results of the CROP03 deep seismic reflection profile, Mem. Soc. Geol. It., 52, 657 pp., 1998.

  46. Selvaggi, G. and A. Amato, Subcrustal earthquakes in the Apennines (Italy): Evidence for a still active subduction?, Geophys. Res. Lett., 19, 2127–2130, 1992.

  47. Serri, G., F. Innocenti, and P. F. Manetti, Geochemical and petrological evidence of the subduction of delaminated adriatic continental lithosphere in the genesis of the Neogene Quaternary magmatism of central Italy, Tectonophys., 223, 117–147, 1993.

  48. Siripunvaraporn, W. and G. Egbert, REBOCC: An efficient data-subspace inversion for two-dimensional magnetotelluric data, Geophysics, 65(3), 791–803, 2000.

  49. Sneider, R., Large scale waveform inversions of surface-waves for lateral heterogeneity—II: Application to surface waves in Europe and the Mediterranean, J. Geophys. Res., 93(B10), 12067–12080, 1988.

  50. Spakman, W., S. van der Lee, and R. van der Hilst, Travel-time tomography of the European-Mediterranean mantle down to 1400 km, Phys. Earth Planet. Inter., 79, 3–74, 1993.

  51. Ting, S. C. and G. W. Hohmann, Integral equation modeling of three-dimentional magnetotelluric response, Geophysics, 46, 182–197, 1981.

  52. Wannamaker, P. E., G. W. Hohmann, and S. H. Ward, Magnetotelluric response of three-dimensional bodies in layered earth, Geophysics, 48, 1517–1533, 1984.

Download references

Author information

Correspondence to E. Armadillo.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark


  • Lower Crust
  • Conductive Layer
  • Induction Vector
  • Conductive Body
  • Magnetotelluric Data