In fact lava flows are lest dangerous to human life than anything else the volcano has in its armoury. The main reason for which is because lava flows are generally slow enough for humans to get out of the way. Unfortunately once an evacuation has been made of a town or city the lava flows can still cause huge damage to property. However volcanoes still have and cause huge lost of live through the use of other methods.
Pyroclastic flows are a deadly concoction of hot ash, gases and usually large boulders. These flow down the slope of a volcano with great velocity and internal temperatures that sometimes exceed eight hundred degrees centigrade. There have been many examples where pyroclastic flows have killed countless lives. Twenty nine thousand people lost their lives to the pyroclastic flow from Mont Pelee, on the Caribbean island of Martinique. This catastrophic event took place in nineteen hundred and two with very little warning.
Other hazards from volcanoes are lahars otherwise know as mudflows. These can form many different ways each as destructive as the last. They can form when hot lava melts a glacial or when a pyroclastic flow meets a river. These have also caused huge damage to life and property. They can flow straight into a town or city just like lava flows. Only lahars are usually faster than lava flows. Lahars can also be formed when there is heavy rain after a volcanic eruption. The layers upon layers of ash turn into a thick river of mud.
There are many different types of eruptions from explosive to quite tame. Different types of magma beneath the volcano cause them. The greater the gas content and the magmas viscosity the more explosive. Like wise, the lower the gas content is and the runnier the magma is the less violent the volcano will be. The more fluid the magma the less it stops the escape of gases therefore pressure does not build up. Volcanoes with viscous magma and a high gas content are extremely dangerous and have great power.