"To understand dynamic earth processes it is necessary to first understand how magmas flow. Volcanology, geodynamics and planetary sciences all need to know at which stresses magma will behave in a ductile or brittle manner and, even more importantly, the range of the transitional brittle-ductile field.With RHEA we aim to separate the stable from the metastable flowing field of crystal bearing melts and estimate the onset of brittle behavior. This question will be addressed by investigating experimentally and numerically the energy distribution within magmas. For the first time we will be able to reproduce numerically the real behavior of samples deformed at high pressure and temperature. We will thereby obtain much better comprehension of the processes involved during magma deformation.This project involves collaboration between excellent universities in Europe and USA: the ETH Zürich renowned for its experimental expertise and the UC Berkeley for the originality of its numerical methods. Combining the individual strengths of these two groups will allow us to develop one of the first numerical rheometers for magmatic suspensions based on real measurements and to formulate new constitutive laws for larger scale models.During the return period, we aim to experimentally test our results on real volcanic systems and to better constrain how the overall change in rheology may explain transitions in eruptive styles.This project will develop new models applicable to a broad range of earth science disciplines. It will allow a better prediction of volcanic eruptions and the results obtained will be invaluable in supporting decision-making during crisis events."