ABSTRACT:

New geophysical monitoring networks combine broadband seismic receivers, hydrophones and micro-barometers antenna. Exploiting these observations requires accurate and multi-media (elastic, hydro-acoustic, infrasound) wave simulation methods which are able to properly model the energy exchanges at the material interfaces.

This has been our motivation to develop a new Hybridizable Discontinuous Galerkin (HDG) method for solving elastic and acoustic wave propagation, with an arbitrary high order of accuracy in space.

In order to introduce this method, we first derive the transmission conditions between heterogeneous elastic, acoustic, and elasto-acoustic media using the Rankine-Hugoniot relations. These conditions are then used to design the inter-element numerical traces in an HDG framework, which make this method able to model both elastic and acoustic waves in the same simulation. We subsequently perform a space discretization using a spectral approach, and we propose a time-scheme able to enforce properly the algebraic transmission equation. The spectral accuracy of the method is assessed on both elastic and elasto-acoustic benchmarks, and some validation benchmarks for the PML are performed. Finally we present some more realistic simulations of coupling between elastic waves and acoustic or hydro-acoustic waves.