Abstract
Ultrafast ultrasonic speckle interferometry, an imaging technique derived from elastography, is used to follow the dynamic of the interface failure in a friction experiment. Experimental results that characterise two slipping regimes are presented: a slow slip regime associated with depinning events at the interface and a supershear rupture regime associated with the emission of Mach waves fronts. These results are discussed in the light of geophysical observations made at the scale of the Earth on the slip dynamics in active faults.