Accurate computation of leaky modes for anomalous layered models

Current research in seismic exploration or seismological engineering has been focused in shallow subsurface, which usually consists of unconsolidated sediments or weathered bedrock, or other types of anomalous medium properties characterized by high Poisson's ratios. In such cases leaky waves may occur either as noise needed to be suppressed or as useful information to reveal the underlying seismic structure. Analysis may be undertaken in terms of leaky modes, which have been conventionally computed based on Haskell matrix method that suffers inherent shortcoming of loss of precision at high frequencies, or have been calculated in the real-number domain but with crude accuracy. An alternative method is proposed herein based on the generalized reflection/transmission coefficients, which searches the roots in the complex wavenumber domain and calculates the leaky modes naturally. This method is then tested for several typical anomalous layered models, and has been proved to be accurate and stable, and thus superior over the traditional methods. A powerful and efficient analyzing tool is thus offered and may be promisingly applied in seismic prospecting, geotechnical engineering, structural dynamics and other relevant areas.;Current research in seismic exploration or seismological engineering has been focused in shallow subsurface, which usually consists of unconsolidated sediments or weathered bedrock, or other types of anomalous medium properties characterized by high Poisson's ratios. In such cases leaky waves may occur either as noise needed to be suppressed or as useful information to reveal the underlying seismic structure. Analysis may be undertaken in terms of leaky modes, which have been conventionally computed based on Haskell matrix method that suffers inherent shortcoming of loss of precision at high frequencies, or have been calculated in the real-number domain but with crude accuracy. An alternative method is proposed herein based on the generalized reflection/transmission coefficients, which searches the roots in the complex wavenumber domain and calculates the leaky modes naturally. This method is then tested for several typical anomalous layered models, and has been proved to be accurate and stable, and thus superior over the traditional methods. A powerful and efficient analyzing tool is thus offered and may be promisingly applied in seismic prospecting, geotechnical engineering, structural dynamics and other relevant areas.