Magnetic Geophysical Method Essay Example | Topics and Well Written Essays - 3000 words

Magnetic Geophysical Method - Essay Example Steel objects buried in the earth also help in the production of the strong anomalies or magnetic fields. The magnetic field of the earth can be approximated in the sense that the magnetic dipole is situated slightly off the center of the earth and that the dipole is incline close to fifteen degrees to the axis of the rotation (Sherriff97). The magnetic field of the earth is believed to be developed by a dynamo that is driven by convection currents in the molten core of the earth. Instrumentation Magnetometers are the instruments which are used in this method to take measurements of the magnetic field of the earth. The field of strength or the intensity of the magnetic field of the earth is actually what is measured by the magnetic geophysical method, and it is measured in terms of Tesla (T). There are various types of magnetometers used in this method. The magnetometer used usually reflects the physical process whereby the magnetic field of the earth is measured. These types of magn etometers used are highly accurate and reliable in the field. They can be able to measure the local magnetic field of the earth to a high precision degree. ... If there is no external magnetic field on the earth, there will be a cancellation of the primary coils. If there is the presence of the external magnetic field, one of the primary coils in the instrument will tend to saturate before the other primary coil. This then leads to the creation of an imbalance in the magnetic field that is to be detected through the induction of EM in the secondary coil (Mishra40). The proton precession instrument that is used by environmentalists and engineers is characterized by a sensor that has a fluid similar to kerosene that is hydrogen rich. For the instrument to be successful in the magnetic geophysical method, a strong magnetic field is created by an inductor to the fluid which leads to the alignment of the protons. After the suspension of the inducted current, the rate of relaxation is recorded as the protons tend to return to the ambient magnetic conditions. The magnetic field of the earth is directly proportional to the relaxation rate (Mishra45 ). A variation on the proton precession magnetometer can be presented by an overhauser magnetometer by the use of the magnetic fields from the radio frequency to produce the polarizing signal. By this, the results given by the proton precession magnetometer is improved because the procession signal is not interfered with by the radio frequency used. The gradiometer magnetometer tends to measure the gradient of the magnetic field of the earth rather than measuring the total strength of the field. Though the magnetic gradient anomalies are not highly useful to geological operations, they are helpful in the provision of a better definition of shallow features that are buried for example drums and tanks. The gradiometer magnetometers are useful in areas