Volcanoes are one the most destructive natural disasters. It is a frightening spectacle, but not usually for the popular reasons. There is so much more to volcanoes than glowing lava.
Lava is the most visible and well-known aspect of volcanoes. It is a tourist attraction in Hawai’i. It is a television news spectacle when is threatens houses and forests. It is flashy and impressive, but except for during large eruptions, it is actually little danger to anything mobile unless the lava surrounds it. It is not nearly the largest threat to loss of life.
The explosive force of the eruption is another large, showy aspect. It can kill, without a doubt, but volcanoes are rarely completely unexpected and those who can get away from it can easily do so in plenty of time.
Pyroclastic flows and lahars are masses of hot gas, mud, ash, and rocks that flow down a mountainside at huge speeds. Entire cities have been wiped out in the past from a volcano that no one was worried about. The Seattle Washington area is in danger from Mount Rainier due to the glaciers and the possibility of lahars. They are unpredictable, but not all that common.
Earthquakes often accompany volcanic eruptions and often precede them, leading some to think that the earthquakes can set off volcanoes. These earthquakes are often deep and relative minor. Compared to the volcano itself, the earthquakes are of little importance.
Almost every volcano is going to set off landslides in the area. People can be caught in them, but these are localized events and is not a great danger.
A greater danger than most of those on the list so far is fire. Volcanoes give off a huge amount of heat, which can set entire forests ablaze. These fires can spread for days or weeks, depending on weather conditions.
The greatest danger, in terms of lives lost, is the ash, dust, and gasses given off into the atmosphere from an erupting volcano. The massive amounts of carbon dioxide, sulfur dioxide, rock dust, and volcanic ash has overcome thousands of people. Cities like Pompeii have been wiped out by smothering the people with the toxic gasses and then covering them with the ash. When the air you breathe can kill, you are in serious trouble. Thankfully, like the eruption itself, people can see the signs coming and get out of the way.
Volcanoes are deadly events. The explosion, the lava, and the flows are all integral parts of the disaster, but the secondary aspects of earthquakes, landslides, and the atmospheric effects from the eruption can be even more deadly. Fortunately, unlike some other disasters such as earthquakes and tidal waves, volcanoes give plenty of signs that things are about to get real, giving people time to go visit relatives and watch the event from a distance.