Synthetic study on SS waveform splitting and complication

摘要

Some influential factors on the complication of SS waveform (with epicentral distance within 40°-180°) are analyzed quantitatively by calculating the full-wave synthetic seismogram using propagation matrix method. Our re-sults show that the transmission-conversion and reflection-conversion phases of S wave at the interface of Moho and free surface beneath bounce points are mainly responsible for the complication of SS waveform, the velocity contrast between the two sides of Moho boundary under SS bounce point also has great effects on the amplitudes of all the conversion and the reverberation phases; the properties of the crust at seismic station also play a role in the complication of SS waveform while the crustal thickness beneath bounce point is thinner relatively. At the same time, two sets of real SS waveform data at the two positions in eastern and western China are analyzed, and the splitting time between SS transverse component and radial component is measured by cross-correlation. Our analysis demonstrates that there is a positive correlation between crustal thickness and the splitting time because of the influences of adjacent conversion and reverberation phases, the splitting time in west with thick crust is obviously greater than that in the east with thin crust. Moreover, It is promising that one new method of measurement of crustal thickness will be developed by using the observed SS splitting time.