A rockslide took place at 10.33 a.m on November 29, 1987, starting from a location 4350 m above sea level on the western slope of Cerro Rabicano in the headwaters of Estero Parraguirre, a tributary of the Río Colorado, Regíon Metropolitana, Chile. It consisted mostly of limestone with gypsum and andesites, and was ~6.0 × 10⁶ m³ in volume. The slide quickly became a rock avalanche, and later a hyperconcentrated debris flow with a volume of at least 15 × 10⁶ m³ due to the incorporation of snow, ice, and sediments from the floor of Estero Parraguirre. Frontal waves were 20–30 m high; the high-energy flow moved with enormous destructive power, first through the channel of Estero Parraguirre, and later through the Río Colorado valley, and finally emptied into the Río Maipo after traveling ~57 km and descending a vertical distance of ~3400 m. During its rapid movement down the Río Colorado, the debris flow killed at least 37 people, and caused serious damage to the Maitenes hydroelectric plant (24 MW) and another hydroelectric plant (Alfalfal, 160 MW) that was under construction. The identification of several diamicton units deposited by prehistoric mud and debris flows in the valley of the Río Colorado, together with the enormous energy and great magnitude of destruction of the November 29, 1987, landslide event, confirm that this type of process is one of the major geological hazards in the Andean valleys of central Chile.