Oliver Plümper , David Wallis, Evangelos Moulas, Stefan M Schmalholz, Hamed Amiri, Thomas Müller

Fluid-rock interactions play a critical role in Earth’s lithosphere and in engineered subsurface systems. In the absence of chemical mass transport, mineral-hydration reactions will be accompanied by a solid-volume increase that may induce differential stresses and associated reaction-induced deformation processes, such as dilatant fracturing to increase fluid permeability. However, the magnitudes of stresses that manifest in natural systems remain poorly constrained. Here we show that the simplest hydration reaction in nature MgO + H2O⇔ Mg(OH)2 can induce stresses of several hundred megapascals, with local stresses up to ∼1.5 GPa. We demonstrate that these stresses are dissipated not only by fracturing but also induce plastic deformation
with dislocation densities (10^15m−2) exceeding those typical of tectonically deformed
rocks. If these reaction-induced stresses can be transmitted across larger length scales they may influence the bulk stress state of reacting regions. Moreover, the structural damage induced may be the first step towards catastrophic rock failure, triggering crustal seismicity.