Obviously it depends on the type of text you are writing. Your description is not very technical, but if you want to describe the eruption in a way that is entertaining and dramatic then, yes, what you have said is fine.
It's difficult to say how I would describe an eruption. Again it depends on my intended audience, but also there are a lot of different things to describe. If I wanted to talk about Pompeii, then I might say something like 'clouds of red-hot ash, rocks and gases exploded from the mountain and descended on the people below, killing them in an instant".
Can I suggest you search the internet for stories about the eruptions of Vesuvius or Mount St Helens, as this will give you some really good examples of how people describe these events?
Hope this helps