Determining crustal structure beneath seismic stations overlying a low-velocity sedimentary layer using receiver functions

The receiver function (RF) technique has been widely applied to investigate crustal and mantle layered structures using P-to-S converted (Ps) phases from velocity discontinuities. However, the presence of low-velocity (relative to that of the bedrock) sediments can give rise to strong reverberations in the resulting RFs, frequently masking the Ps phases from crustal and mantle boundaries. Such reverberations are caused by P-to-S conversions and their multiples associated with the strong impedance contrast across the bottom of the low-velocity sedimentary layer. Here we propose and test an approach to effectively remove the near-surface reverberations and decipher the Ps phases associated with the Moho discontinuity. Autocorrelation is first applied on the observed RFs to determine the strength and two-way traveltime of the reverberations, which are then used to construct a resonance removal filter in the frequency domain to remove or significantly reduce the reverberations. The filtered RFs are time corrected to eliminate the delay effects of the sedimentary layer and applied to estimate the subsediment crustal thickness and V-P/V(S)using a H-k stacking procedure. The resulting subsediment crustal parameters (thickness and V-P/V-S) are subsequently used to determine the thickness and V-P/V-S of the sedimentary layer, using a revised version of the H-k stacking procedure. Testing using both synthetic and real data suggests that this computationally inexpensive technique is efficient in resolving subsediment crustal properties beneath stations sitting on a low-velocity sedimentary layer and can also satisfactorily determine the thickness and V-P/V-S of the sedimentary layer.