  Given an Anosov representation $\rho \colon \pi_1(S) \to
\PSL_{n}(\mathbb{R})$ and a maximal geodesic lamination $\lambda$ in a surface
$S$, we construct shear deformations along the leaves of the geodesic
lamination $\lambda$ endowed with a certain flag decoration, that is provided
by the associated flag curve $\mathcal{F}_\rho\colon \Sinf \to
\mathrm{Flag}(\mathbb{R}^n)$ of the Anosov representation $\rho$; these
deformations generalize to Labourie's Anosov representations Thurston's
cataclysms for hyperbolic structures on surfaces. A cataclysm is parametrized
by a transverse $n$--twisted cocycle for the orientation cover $\La$ of
$\lambda$. In addition, we establish various geometric properties for these
deformations. Among others, we prove a variation formula for the associated
length functions $\ell^i_\rho$ of the Anosov representation $\rho$.

Geometric Topology