Complex Semblance and Its Application

Semblance, a measure of multi-trace coherence, has been used extensively in seismic data processing and interpretation such as velocity analysis and fault detection. The traditional algorithm has a difficulty at zero-crossings of seismic recordings. This problem is alleviated by applying a smoothing window at the cost of losing vertical resolutions. In this paper, we improve the algorithm by computing semblance from complex traces. Our initial results show that the complex semblance is smooth at zero-crossings. Because the smoothing time window becomes unnecessary, the higher vertical resolution can be achieved by using small windows or none. Some geological features, like faults and unconformities, appear clearer and easier to identify with the complex semblance. As the advantages are obvious and the implementation is straight-forward with the Hilbert transform, this new algorithm may replace the traditional one in future applications.