Equivalent Layer Processing of Geophysical data

Processing of magnetic and gravity data to remove noise or enhance features of interest is a<br>common requirement. Vertical continuation (to and from both flat surfaces and surfaces of<br>variable elevation) and the calculation of the vertical gradient are performed here using an<br>equivalent layer rather than the usual frequency domain methods. The first step is to invert the<br>data to give the density contrast of a thin surface layer of cylinders which produces the same<br>anomaly as the observed data profile. The layer’s geophysical response can then be calculated at<br>other locations, to yield upward continued and vertical gradient data. The equivalent layer<br>method does not impose many of the stringent requirements on the data that fast Fourier<br>transform methods do, namely data stationarity, equal data sampling intervals, or the need for 2ⁿ<br>data points.