Exploratory data analysis of flexural waves in Arctic fjord ice seismic data

Abstract

A seismic source on floating ice induces flexural waves in the ice layer. An exploratory data analysis of Arctic fjord ice seismic data is performed for the purpose of identifying and studying characteristics of flexural waves and other related wave modes. Both geophone and hydrophone data are examined with the purpose of studying ice properties from ice wave behavior. Power spectral density estimates provide the frequency content of the entire signal, and studies of time-frequency plots have revealed both dispersive and non-dispersive ice related waves and their corresponding frequencies. F-k spectra are applied to study the dispersion relation for both flexural and acoustic ice waves. This provides the (variation in) wavelengths for the different waves. Velocities of the flexural waves are obtained by cross-correlating receivers at known offsets and by combining the obtained wavelengths with the period found from single receiver traces. Other observed waves include a guided direct wave in ice, a seafloor reflection and its multiples, and a refracted wave. The combination of several analysis methods makes it possible to identify several characteristics and properties of floating ice related waves, contributing to the understanding of such wave behavior. Wave characteristics of flexural and acoustic ice waves are combined to find ice properties like thickness and rigidity.