of the order of $10^3-10^6$yrs [@Jones1988; @Goldreich1992; @Pons2007; @Pons2009; @Gourgouliatos2016], by itself too slow to explain this phenomenology. Two complementary models have tried to explain these observations. In the [*crustquake*]{} model [@Thompson1996; @Perna2011] the dynamical trigger is the mechanical failure of patches of the magnetar crust due to large stresses built during its magneto-thermal evolution. Numerical simulations of the Hall evolution of the crust [@Vigano2013] show that it is possible to recurrently reach the maximum stress supported by the very same [@Horowitz2009; @Baiko2018]. At this point, the crust likely becomes plastic [@Levin2012], i.e. the crust generates thermo-plastic waves emerging from such a localized trigger, or in other words *yields* [@Beloborodov2014; @Li2016]. The waves propagate into the magnetosphere, probably resulting in rapid dissipation through a turbulent cascade triggered by reconnection on slightly displaced flux surfaces [@Thompson1996; @Thompson2001; @Li2018]. The energy released in those events suffices to explain the observed luminosities, even for GFs [@Thompson1996; @Lander2015]. The burst duration ($\sim 0.1$s) is related to the crossing time of shear waves through the whole crust ($1-100$ ms). A limitation is that, if stressed for long periods of time ($\sim 1\,$yr) as it is the case due to the slow magneto-thermal evolution, the crust 