Most volcanic eruptions are violent, dangerous and life threatening.
The worst form is when a pyroclastic flow of fast-moving lava, pieces of rock, volcanic ash and hot gases erupts like a cannon from the volcano. The flow can travel at speeds of upwards of 600 kilometres per hour giving anything in its path no chance of survival. What is called a lahar, a mudflow containing volcanic material, can form when the pyroclastic flow mixes with water to create a broiling flow of red hot slurry at temperatures as high as 700°C.
Here is a video of the terrifying pyroclastic flows at the Sinabung volcano: Indonesia in 2014.
In 1902, on Martinique, pyroclastic material from the Mount Pelée eruption killed most (30,000) of the population of the city of Saint-Pierre. Pompeii and Heraculaneum were flattened in 79 AD by pyroclastic flows. There were huge pyroclastic flows when the Greek island of Santorini erupted in BCE 3,600. The 1883 eruption at Krakatoa was also a pyroclastic event. Mount Unzen (Japan), Mosquito Ghaut (Monserrat) and the Fuego volcano (Guatemala) are clear evidence that dangerous volcanic activity is commonplace on earth.