 Complete the following phrase:  The volcano usually generates Vulcanian to Plinian eruptions, which produce swift-moving currents of hot gas and rock called pyroclastic flows. These eruptions often cause massive lahars mud and debris flows, which pose a threat to human life and the environment. The impact of such an eruption is increased as the hot gas and lava melt the mountains snowcap, adding large quantities of water to the flow. On November 13, 1985, a small eruption produced an enormous lahar that buried and destroyed the town of Armero in Tolima, causing an estimated 25,000 deaths. This event later became known as the 