On the Application of Phase-Weighted Stacking to Suppression of Sediment Reverberations in Receiver Functions

Date: 4/26/2019

Time: 06:00 PM

Room: Grand Ballroom

Teleseismic receiver function (RF) analysis is now a preeminent methodology for imaging the Moho using passive seismic data. Since the method’s inception, reverberations within shallow sediment layers have presented a formidable obstacle to RF practitioners due to their tendency to overprint deeper converted arrivals usually targeted for study. Significant progress toward mitigation of shallow reverberations in receiver functions is advancing on several fronts: data-driven approaches like sequential H-K stacking, and model-based approaches ranging from reverberation removal filters to full-waveform inversion. Here, we hope to demonstrate a simple tool to augment all approaches by constraining the arrival times of Moho Ps, using RF phase information obtained via the Hilbert Transform to clearly identify conversions whose amplitudes may otherwise be obscured by shallow reverberations.

We show that, prior to the arrival of the Moho Ps phase, the Phase-Weighted Stack (PWS) of slowness-binned RFs closely matches the impulse response of the sediment layers, given the sediment reverberations do not exhibit significant moveout. When the Moho Ps arrives, the Phase Stack diverges from unity due to the moveout of the crustal arrival. Thus, so long as the sediment reverberations do not move out, the residual between PWS and binned RFs can be used to identify the arrival times of the Moho Ps phase, even if its amplitude is overprinted by shallow reverberations.

In the course of developing this method, we investigated the practical limitations of applying PWS to RF data using numerical experiments, from which we derived basic constraints useful to assess the validity of applying PWS to real data. We show that, for RFs constructed from Gaussian pulses, PWS artifacts correlate with deviations from Gaussian support in RF instantaneous frequencies and vanishing RF amplitudes. Using these observations to implement minimal PWS quality-control, we show significant improvement in reverberation removal results for synthetic data and TA stations in the Williston Basin.

Presenting Author: Justin S. Ball

Authors