Transient electromagnetic responses in seafloor with triaxial anisotropy |
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| Authors: | L Yu R L Evans R N Edwards |
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| Institution: | Geophysics Laboratory, Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7, Canada |
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| Abstract: | Electrical anisotropy of young oceanic crust at mid-ocean ridges is detectable by observation of the rate and geometry of the diffusion of electromagnetic fields. The anisotropy in electrical properties arises from the presence of conductive seawater in an interconnected network of mostly ridge-parallel cracks. In this paper, we first justify the choice of a triaxial model to represent young oceanic crust, with three distinct electrical conductivities in the vertical, strike and spreading directions. We then present an algorithm to calculate the transient electromagnetic responses generated by an electric dipole source over such a triaxially anisotropic seafloor. We show that if the transient passages are measured with three distinct electric dipole-dipole configurations, it is possible to discern all three unknown conductivities independently of each other. |
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| Keywords: | cracks electromagnetic methods mid-ocean ridges triaxially anisotropic conductivity |
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