Butterworth band-pass filter has been applied to S-wave data recorded at 8
stations in China mainland, and S-wave splitting at different frequency ban
ds is analyzed. The results show that the delay time and the fast polarizat
ion directions of S-wave splitting depend upon the frequency bands. There i
s an absence of S-wave splitting at the station of Urumqi (WMQ) for the ban
d of 0.1-0.2 Hz. With the frequency band broadening, the delay time of S-wa
ve splitting decreases at the stations of Beijing (BJI), Enshi (ENH), Kunmi
ng (KMI) and Mudanjiang (MDJ); the fast polarization direction changes from
westward to eastward at Enshi (ENH), and from eastward to westward at Hail
aer (HIA). The variations of delay time with bands at Lanzhou (LZH) and Qio
ng-zhong (QIZ) are similar, and there is a coherent trend of fast polarizat
ion directions at BJI, KMI and MDJ, respectively. Initial interpretations t
o the results of frequency band-dependence of S-wave splitting are also pre
sented.