Koreksi Variasi Harian untuk Survei Geomagnetik di Daerah Potensi Uranium dan Thorium, Mamuju Sulawesi Barat

Geomagnetic method is a geophysical method that can be performed to determine the susceptibility of the medium at the measurement location. Diurnal variation correction is used to remove the effect of external magnetic field on the measured magnetic field value. Geomagnetic method measurements performed using two measuring tool to get better results. The first tool is placed in a specific location (base) and is set to take measurements automatically in a certain period. The second tool is used to make measurements at the points specified in the survey design. The location of the research was conducted in Takandeang, Mamuju, West Sulawesi. Measurements at the base are done to obtain diurnal variation data that will be corrected to measured field data (rover). This study aims to determine the value of the diurnal variation for different locations. The method of determining base correction for different base locations can be applied to solve the problem of base location difference especially for surveys with large area. The data used to correct are the data that obtained from base 2 and the other base (1 or 3) on the same day. Correction of base 1 to base 2 is taken from the measurement results on 16, 28 and 29 September 2016. The correction of base 3 to the base 2 is taken from the measurement results on 10, 28 and 29 September 2016. The correction value for the base 1 to base 2 is 72.50 nT. A correction value for base 3 to base 2 is 40.25 nT. This value is derived from calculations with the help of a linear curve. This value is the difference between the value of the base 2 with base 1 and 3.