Improved Green’s functions for passive-source structural studies

Abstract

Over the past two decades, teleseismic receiver functions have proved to be a useful tool to investigate crustal structure. Because they represent a first-order approximation to the Swave component of the teleseismic-P Green's function, receiver functions provide valuable information on physical properties related to shear modulus. However, the implicit use of the P-component seismogram as a proxy for the source precludes the recovery of information on discontinuous structure involving contrasts in compressional modulus. By deconvolving improved estimates of complex source time functions generated by earthquakes, one may move beyond the conventional receiver function paradigm to a more accurate approximation of the earth's Green's function. Using a new deconvolution method, we present estimates of the P-component of the teleseismic-P Green's functions at several stations of the Canadian National Seismic Network ͑CNSN͒ that clearly show the receiver-side pure P-wave crustal multiple. The identification and characterization of these signals in studies of the lithosphere will afford better constraints on subsurface lithology and represent a narrowing of the gap between active-and passive-source seismic imaging.

Three-dimensional wavefield imaging of data from the USArray: New constraints on the geometry of the Farallon slab

“…For a typical crustal thickness, P pMs arrives ~10 s after P with a positive polarity, while P sMs has a negative polarity and arrives ~18.5 s after P (e.g., see Fig. 5 of Mercier et al, 2006). When treated as primaries in this migration algorithm these multiples would map to the approximate depths of the two features tagged with question marks in Figure 2.…”

A rootless rockies—Support and lithospheric structure of the Colorado Rocky Mountains inferred from CREST and TA seismic data

“…Finally, the receiver function spectral phase is reconstructed by exploiting the minimumphase nature of the direct-component trace. The details of this methodology are presented elsewhere [Baig et al, 2005;Bostock, 2004;Mercier et al, 2006], and the application to temporary array recording and S wave data was demonstrated by Hansen and Dueker [2009]. We note several advantages afforded by this approach.…”

Theory and Observations - Seismology and the Structure of the Earth: Teleseismic Body-Wave Scattering and Receiver-Side Structure

“…, whereas the phase of the two remaining quantities can be recovered through a slightly more involved procedure described by Mercier et al (2006). An example showing the teleseismic P Green function estimates as a function of horizontal slowness for station HYB at Hyderabad, India, is shown in Figure 5.…”

“…In fact, the phase of all three components of motion (or, more specifically, upgoing P, SV, and SH), as well as the source, need not be considered until their respective amplitude spectra have been recovered. As explained by Baig et al (2005) and Mercier et al (2006), estimation of, for example, the source amplitude spectrum can be accomplished by considering the cross spectrum of two seismograms sharing that source. As an example, consider two components P and SV of the same three-component recording represented in the frequency domain as P(o), V(o).…”