CONSTRAINING THE THICKNESS OF EUROPA ’ S ICE SHELL WITH OBSERVATIONS OF FUNDAMENTAL MODE RAYLEIGH WAVE DISPERSION
Introduction: Geophysical evidence from the Galileo mission hints that Europa’s ice shell is underlain by a global water ocean (e.g., [13]). However, the thickness of the ice shell and the connectivity between the ocean and surface is still unclear. Seismology offers a promising means of probing Europa’s ice shell structure since tidally induced ice fracturing events provide a natural source of seismic energy to illuminate the subsurface (e.g., [4 6]). A future seismic lander mission to Europa will likely employ a variety of techniques to image the interior, including body wave, surface wave, and normal mode seismology. Here, we use numerical simulations of seismic wave propagation on Europa in order to investigate the potential of using surface wave dispersion measurements to constrain the ice shell thickness. Numerical simulations of wave propagation: We simulate seismic wave propagation through thermodynamically self-consistent models of Europa’s interior [7] at frequencies up to 1 Hz using the spectral-element method (SEM) code AxiSEM [8] (Fig. 1). The modeling suggests that Mw 3 or greater events, which may be fairly common on Europa (e.g., [9]), are likely to produce Rayleigh waves that could be observed globally by commonly employed seismic instruments.