Dispersion of Rayleigh Waves across Australia

Summury The history of seismological investigations of Australian crustal structure is outlined. New measurements have been made of phase and group velocities of Rayleigh waves for a number of continental paths. The most extensive empirical dispersion curve comes from a Solomon Islands earthquake which lies near a great circle through the Charters Towers and Perth observatories. This curve is in general agreement with published values for the Canadian Shield. It indicates a mean crustal thickness between 30 and 35 km. Some variation in crustal properties is indicated towards the northwest. The average crust under the Coral Sea may be 30 per cent thinner than that under the continent. In this paper measurements of dispersion in Rayleigh waves recorded at Brisbane, Charters Towers and Perth seismological observatories are presented. Comparison of these data with similar measurements for the Canadian Shield and with theoretical dispersion curves provides fresh evidence on the structure of the Australian continental crust. Broadly, the continent may be divided into three main geological provinces (cf. Bureau of Mineral Resources, 1960). The great Pre-Cambrian Shield, with