Interplay of seismic and aseismic deformations during earthquake swarms: An experimental approach

Olivier Lengliné (1) , J.E. Elkhoury (2) , Guillaume Daniel (3) , Jean Schmittbuhl (1) , Renaud Toussaint (4, 5) , J.-P. Ampuero (2) , Michel Bouchon (6)

1 IPGS-Sismologie - Sismologie (IPGS)
2 Division of Geological and Planetary Sciences [Pasadena]
3 Magnitude, Research and Development
4 IPGS-GE - Géophysique expérimentale (IPGS)
5 Centre for Advanced Study at the Norwegian Academy of Science and Letters
6 ISTerre - Institut des Sciences de la Terre

Observations of earthquake swarms and slow propagating ruptures on related faults suggest a close relation between the two phenomena. Earthquakes are the signature of fast unstable ruptures initiated on localized asperities while slow aseismic deformations are experienced on large stable segments of the fault plane. The spatial proximity and the temporal coincidence of both fault mechanical responses highlight the variability of fault rheology. However, the mechanism relating earthquakes and aseismic processes is still elusive due to the difficulty of imaging these phenomena of large spatiotemporal variability at depth. Here we present laboratory experiments that explore, in great detail, the deformation processes of heterogeneous interfaces in the brittle-creep regime. We track the evolution of an interfacial crack over 7 orders of magnitude in time and 5 orders of magnitude in space using optical and acoustic sensors. We explore the response of the system to slow transient loads and show that slow deformation episodes are systematically accompanied by acoustic emissions due to local fracture energy disorder. Features of acoustic emission activities and deformation rate distributions of our experimental system are similar to those in natural faults. On the basis of an activation energy model, we link our results to the Rate and State friction model and suggest an active role of local creep deformation in driving the seismic activity of earthquake swarms.

Mots clés: seismic swarm; acoustic events; fracture propagation

Domaines: Sciences de la Terre; Mécanique des solides [physics.class-ph]; Mécanique des solides [physics.class-ph]

Olivier Lengliné, J.E. Elkhoury, Guillaume Daniel, Jean Schmittbuhl, Renaud Toussaint, et al.. Interplay of seismic and aseismic deformations during earthquake swarms: An experimental approach. Earth and Planetary Science Letters, 2012, 331-332, pp.215-223. ⟨10.1016/j.epsl.2012.03.022⟩. ⟨hal-00701955⟩