The checks by the vertical first derivative and secondderivative anomalies reduced to the pole show good coincidence, which proves the reliability of the shallow layer anomaly.
经过化极垂向一次导数和垂向二次导数的验证，吻合很好，说明浅部异常的可信度高。
2
As the secondderivative does, the forth, derivative of gravity anomaly projects local anomaly but suppresses regional anomaly.