There are three basic kinds of volcanos.
Composite volcanoes are the popular (in movies), explosive kinds that are tall, cone-shaped, with many chaotic layers of hardened lava and ash that make the overall structure unstable.
Volcán Arrenal, Costa Rica (2005)
Shield volcanoes are the kind you find in Hawaii with regular, thin, quiet lava flows that are usually more mafic (higher concentration of heavier elements). They’re also broad, flat, and much more consistent by structural comparison.
And then there are cinder cones, which are like mini composite volcanoes, very volatile, that mostly spew tephra.
Volcanoes–especially composites–have caused quite a bit of devastation to mankind throughout history from Mt. Vesuvius to Mt. St. Hellens. A few science fiction flicks have even attempted to capture the awesomeness that is volcanic destruction…and failed miserably in my humble geological opinion. (Ahh, I miss watching movies for geology club just so we could make fun of how terrible the speculative geology was…).
Writing Prompt: Active Volcano (ND)
Write a story in which an active volcano of some sort is an inherent part of your alien civilization’s landscape. It could be part of the island on which they live or an imposing nearby mountain. In this story, the volcano is regularly active as opposed to being a dormant volcano that unexpectedly comes to life (which would make things way too easy and a little cliché). Make the volcano’s activity both threatening and important to your civilization–perhaps this is their main source of fresh soil or minerals that they turn into tools and jewelry, but collecting the material or living near the volcano is dangerous. Have the threatening aspect of the volcano’s activity play an important role in the conflicts your civilization–and particularly your main characters–face in their journey.