How the Comet Crumbles: Mass Wasting Drives Outbursts on Comet 67P/Churyumov-Gerasimenko

Cometary nuclei are active geological worlds, continually reshaped as they shed primitive ices and dust. The most extreme phenomena driving this evolution are outbursts, short-lived events capable of ejecting hundreds of tonnes of material in minutes. Yet their role in sculpting cometary landscapes has remained obscure. Even on comet 67P/Churyumov–Gerasimenko, observed in unprecedented detail by ESA’s Rosetta mission, only six of over 40 detected outburst plumes had been linked to observed changes on the surface. Here, through the first systematic analysis of all reported outburst source locations on 67P using the complete OSIRIS image archive, we show that surface change accompanies every outburst with adequate imaging coverage, increasing the number of confirmed cases from six to 37. More importantly, these changes are all expressions of a single process — the mass wasting of mechanically weakened, volatile-bearing material — acting across a continuum of scales and surface morphologies. Where the temporal sequence can be resolved, this surface failure always precedes the outburst, indicating that surface unloading exposes buried volatiles whose rapid sublimation drives the plume. This reframes outbursts not as the cause of surface change but as the energetic expression of an ongoing process of cometary mass wasting.