Multi-scale wavelet decomposition of Bouguer gravity anomaly in Three Gorges and its surrounding regions

Based on the theory of discrete wavelet transform, the multi-scale wavelet decomposition of the Bouguer gravity anomaly in Three Gorges and its surrounding regions was investigated in this paper. Correspondingly, we obtained the regional and local anomalies, as well as the first-to-fourth-order wavelet details. The results show that the EW-trending positive anomaly of Qinling-Dabie orogenic belt exists in the fourth-order wavelet details, which may relate to the interaction between Yangtze block and Qinling-Dabie orogenic belt. The earthquakes with M＞3.0 mostly occurred at the regional anomaly belt with eastward extrusion, which is shown as the negative anomaly regions in the second- and third-order wavelet details, also west of the positive anomaly region of Huangling anticline in the fourth-order wavelet detail. The earthquakes occurred in the Three Gorges region may relate to the neotectonics of the Huangling anticline.