The 1987 Parraguirre ice–rock avalanche developed into a devastating debris flow, causing the loss of many lives and inflicting severe damage near Santiago, Chile. Here, we revise this event, combining various observational records with modelling techniques. In that year, important snow cover coincided with persistent warm periods in spring. We also put forward upward corrections for the trigger and flood volumes involved in this debris flow. Finally, temporary river damming was key for the flow ferocity.