The detection and characterization of discontinuities such as faults in seismic images can be performed by coherency analysis. I analyze the coherency of the instantaneous phase of the complex seismic trace by using circular statistics and defining a complex-valued correlation. The method, applied to neighbouring seismic traces, can extract at once two seismic attributes: correlation amplitude defining coherency and lateral phase shift relating to dip of events. This technique is computationally inexpensive and does not require any scanning or iteration while the local windowing ensures smooth results. I apply the method on real data from Gulf of Mexico.