Global Journal of Earth and Environmental Science

Analytical operations of upward and downward continuations were applied to structural trends obtained from airborne gravity data in parts of Southern Niger Delta of Nigeria with varying depths of 500 to 1,000 m to observe the effects of the continuations on the structural trends. The data were first gridded and the regional effects separated from the residuals using a second-order polynomial operation. The continuation operations show that at a depth of 500 m, both upward and downward continuations did not affect the observed trends much as the difference between the original trends and the ones with continuation operations were almost the same. However, with continuation depths of 1,000 to 5, 000 m, the upward continuations enhanced the sharpness of the structural trends with increasing depths while the downward continuations suppressed and distorted the structural trends with increasing depths. The results confirm the instability in downward continuation operations with increasing depths for long-wavelength regional trends since the operations increases the noise levels exponentially and hence distorts the sharpness of the trends. The enhancement of the regional trends by the upward continuation shows it as a stable operation for long-wavelength regional trends for proper visualization.