Deconvolution of teleseismic body waves for enhancing structure beneath a seismometer array

We discuss three stacking;deconvolution techniques for enhancing signal of Earth structure contained in the seismograms of teleseismic body waves reco rded by a seismometer array. The goal of the deconvolution is to remove fro m the seismograms the complications due to the source. For three-component data, the removal of the source can be efficiently achieved by deconvolving one component from another, as in. the receiver function analysis. In the case of an away, if the structure beneath individual stations varies, the s ource wavelet can be estimated and removed from the seismograms by stacking . This allows structural analysis in the situations when only single-compon ent seismometers are used or when a particular component can provide additi onal independent information. Here we compare the efficacy of conventional time-domain stacking, cepstral averaging, and autocorrelation stacking. The latter is a new approach developed here. For cepstral averaging, we presen t conditions that stabilize the convergence. Examples are presented using s ynthetics and real data from a broadband seismic array experiment conducted in the Cascadia subduction zone (Oregon) in 1993 to 1994. Data from subduc tion zones are particularly well suited because of the spatially rapidly va rying structure. We find that all three methods work well. for low frequenc ies, which are not sensitive to the time alignment of the seismic traces. T he latter two methods do not require precisely aligned seismograms, and the ir advantage becomes evident at higher frequencies where the appropriate ti me alignment is harder to achieve. At high frequencies, time-domain stackin g is likely to fail.