“Before each eruption, the volcano begins to deform. We have installed inclinometers capable of measuring the tiniest deformations, sometimes fractions of a millimetre, that occur when the magma comes up to the surface. We measure this with three instruments, one we installed last year and two more we have just set up. (…) It is not impossible that in a few thousand years, or perhaps sooner, the entire eastern side of the volcano will collapse into the ocean. It is a geological hazard on Reunion, but on a millennial timescale.”