Planetary growth, differentiation and the social impacts from volcanic activity are all linked to the poorly understood dynamics of magmatic systems. MECAMUSH will rationalize the behavior of crystal-rich magmas (mush) by combining novel experimental and numerical modeling techniques. Geological observations point towards two crucial aspects of mush dynamics. 1) Ubiquitous differentiation by melt extraction, which produces mobile, crystal-poor magmas and crystal-rich residues, seems controlled by the dynamics of force chains in the network of crystals. MECAMUSH aims at characterizing these force chains and how they regulate mush rheology from 1-12 Kbars. 2) MECAMUSH will explore the subsequent transition of the mobile magma into a microlite-charged mush during eruption by experimentally characterizing the permeability of three-phase magmas combined with new rheological insights of bimodal suspension to update existing numerical models for volcanic hazard assessment.