Normal mode simulation of prompt elastogravity signals induced by an earthquake rupture

K Juhel (1) , J-P Montagner (2) , M Vallée (2) , J. Ampuero (3) , M. Barsuglia (1) , P. Bernard (4) , P Clévédé (2) , J Harms (5) , P Whiting (6)

1 APC (UMR_7164) - AstroParticule et Cosmologie
2 IPGP - Institut de Physique du Globe de Paris
3 GEOAZUR 7329 - Géoazur
4 IBGC - Institut de biochimie et génétique cellulaires
5 LNGS - Laboratori Nazionali del Gran Sasso
6 UF - University of Florida [Gainesville]

As soon as an earthquake starts, the rupture and the propagation of seismic waves redistribute masses within the Earth. This mass redistribution generates in turn a long-range perturbation of the Earth gravitational field, which can be recorded before the arrival of the direct seismic waves. The recent first observations of such early signals motivate the use of the normal mode theory to model the elastogravity perturbations recorded by a ground-coupled seismometer or gravimeter. Complete modelling by normal mode summation is challenging due to the very large difference in amplitude between the prompt elastogravity signals and the direct P-wave signal. We overcome this problem by introducing a two-step simulation approach. The normal mode approach enables a fast computation of elastogravity signals in layered self-gravitating Earth models. The fast and accurate computation of gravity perturbations indicates instrument locations where signal detection may be achieved, and may prove useful in the implementation of a gravity-based earthquake early warning system.

Domaines: Sciences de la Terre; Physique [physics]; Astrophysique [astro-ph]

K Juhel, J-P Montagner, M Vallée, J. Ampuero, M. Barsuglia, et al.. Normal mode simulation of prompt elastogravity signals induced by an earthquake rupture. Geophysical Journal International, 2019, 216 (2), pp.935-947. ⟨10.1093/gji/ggy436⟩. ⟨hal-02117891⟩