Top: the cumulative probability of the next collision event (a hypothetical Fomalhaut cs3) where the target planetesimal radius is ≥100 km in radius as a function of collision year under the conditions of our model (see Table 3). The shaded regions indicate the 16th and 84th percentiles of the posterior distribution. We find a 50% chance of the next collision occurring in 2027 at the earliest and 2041 at the latest. Bottom: the cumulative probability of the next collision event (Fomalhaut cs3) where the target planetesimal radius is ≥100 km in radius as a function of belt semimajor axis.