 Complete the following phrase:  The 1970 Huascarán debris avalanche occurred on May 31, 1970, when a debris avalanche and mudflow triggered by the Ancash earthquake destroyed the Peruvian town of Yungay and ten nearby villages, leaving up to 30,000 people dead. It is the deadliest avalanche or glacier-related disaster in history, and the third or fourth most deadly landslide-related disaster of the 20th century, after the Haiyuan landslides China, the 