AxiSEM: broadband 3-D seismic wavefields in axisymmetric media
- 1Dept. of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, United Kingdom
- 2Institute of Geophysics, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland
- 3Dept. of Earth Sciences, Ludwig-Maximilians-Universität München, Theresienstrasse 41, 80333 Munich, Germany
- 4Institute of Geophysics, Universität Münster, Correnzstrasse 24, 48149 Münster, Germany
- 5ISTerre, Université Joseph Fourier, Grenoble, BP 53 38041 Grenoble CEDEX 9, France
- 6Institut de Physique du Globe, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, 75005 Paris, France
Abstract. We present a methodology to compute 3-D global seismic wavefields for realistic earthquake sources in visco-elastic anisotropic media, covering applications across the observable seismic frequency band with moderate computational resources. This is accommodated by mandating axisymmetric background models that allow for a multipole expansion such that only a 2-D computational domain is needed, whereas the azimuthal third dimension is computed analytically on the fly. This dimensional collapse opens doors for storing space–time wavefields on disk that can be used to compute Fréchet sensitivity kernels for waveform tomography. We use the corresponding publicly available AxiSEM (www.axisem.info) open-source spectral-element code, demonstrate its excellent scalability on supercomputers, a diverse range of applications ranging from normal modes to small-scale lowermost mantle structures, tomographic models, and comparison with observed data, and discuss further avenues to pursue with this methodology.