MAGNETOTELLURICS AND BASIN ANALYSIS AT SANTA FE RIVER CANYON

Application of Archie’s law for porosity estimation is applied to data collected by the MT (magnetotelluric) method at SAGE 2000 (Summer of Applied Geophysical Experience). The data received are also manipulated to test the sensitivity of MT and its ability to detect basin properties. Starting this project requires research on the properties of Archie’s Law. Calculations from many approximations and overall averages show extremely high salinities for water that may be located at different depths. To test the sensitivity of MT inversions, different starting models with a fault line in various locations were run and examined. Lateral location of the fault, with variations of 2 km from a vertical to a gently sloping contact on the models, does not show variation in the error of the smooth fit line to the data plots. When the basin is dropped approximately 3120 m there is still only a slight variation in the resulting data plots, though with scrutiny the depth can be determined to a reasonable confidence level. Therefore, sensitivity testing on the SAGE 2000 MT data does not give precise models for the lateral location and dip angle of major faults. This may be a result of wide station spacing of approximately 3.2 km apart. If more stations are placed closely around the area of the fault, it may be possible to locate the fault more accurately.