Method of interpretation of magnetotelluric data when source field is considered

The curve-matching method can be used to interpret magnetotelluric data when the wavelength of the source is known. A similar method of interpretation is also suggested for cases where the wavelength of the source is not known. The application of these methods to the determination of the resistivity distribution in shallow as well as in deep regions within the earth is illustrated by means of a few theoretical models. These models show that the source effect is more pronounced in phase angles than in apparent resistivity values. Hence more attention should be given to phase values when determining the resistivity distribution in deep regions within the earth. The models also show that the wavelength of the source can be assumed to be infinite for moderate resistivity distributions at shallow depths.