Inversion of coeval shear and normal stress of Piton de la Fournaise flank displacement

A new method to invert quadrangular curved sources under simultaneous pressure and shear stress changes reveals that the posteruptive eastern flank displacement of Piton de la Fournaise is likely due to compaction and slow slip on a shallow detachment fault. This finding challenges the traditional view that flank displacement is solely induced by fault slip, suggesting instead that it may be linked to lithological discontinuities or sheared sills. The study analyzed data from six Envisat orbits over 14 months post-April 2007 eruption, identifying a large (5 km by 8 km) and shallow (500 m) trapezoidal fracture parallel to the flank. It also ruled out thermal contraction or degassing of a coeruptive sill as the primary cause, given the implausible dimensions and solidification time required.

Tridon, M., Cayol, V., Froger, J.-L., Augier, A., & Bachèlery, P. (2016). Inversion of coeval shear and normal stress of Piton de la Fournaise flank displacement. Journal of Geophysical Research: Solid Earth, 121(11), 7846–7866. Portico. https://doi.org/10.1002/2016jb013330