Riñihuazo
The Riñihuazo is the name given to the landslide damming of Riñihue Lake on 22 May 1960, after a landslide caused by the Great Chilean earthquake blocked its outflow. According to the chronicler Mariño de Lobera a similar event occurred after the 1575 Valdivia earthquake.
During the Great Chilean earthquake, several landslides near Tralcán Mountain blocked the outflow of Riñihue Lake at (39°46′43″S 72°27′03″W / 39.77861°S 72.45083°W). Riñihue Lake is the lowest of the Seven Lakes chain and receives a constant inflow from the Enco River. The blocked San Pedro River, which drains the lake, passes through several towns and the city of Valdivia before finally reaching Corral Bay.
Because the San Pedro River was blocked, the water level of Riñihue Lake started to rise quickly. Each meter the water level rose was equivalent to 20 million cubic meters, which meant that 4.8 cubic kilometers of water would release into the San Pedro River (easily overpowering its flow capacity of 400 cubic meters per second) if it rose above the first, 26-meter-high dam. This potential disaster would have destroyed all the settlements along the course of the river in less than five hours, and had more dire consequences if the dam suddenly broke.
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