Study on Azimuth Variation of Airgun Signal Propagation

Based on the data recorded by the observation network during the intensive excitation period from November to December 2015 at Binchuan Earthquake Signal Transmitting Seismic Station (BESTSS) in Yunnan Province,the noise in waveform recording is removed by S-transform template filtering method,and the azimuth of airgun signal propagation is calculated and analyzed from the horizontal waveform recordings. The results show that:① the azimuth angle of airgun signal after propagation is sensitive to stress change,and can clearly reflect the diurnal variation of tidal stress,which can be used to monitor the change of stress state in crustal medium;② the azimuth angle of airgun signal in some stations has changed abruptly after propagation on December 4,which may be related to the change of airgun source;③ five-shot superposition or fivepoint smoothing of azimuth angle of single shot are carried out for airgun signals in stations far away from epicenter,and results show that azimuth angle from superposition or smoothing is more stable and has clear diurnal variation characteristics after propagation.

Study on Azimuth Variation of Airgun Signal Propagation