As the other comment explains, it isn’t about morality. It’s about practicality. We have the ability to attempt to reduce our impact to keep the planet healthy, so we have an obligation to do so. A volcano doesn’t have that ability.

If we are absolute hedonists, with no long-term considerations, then the world won’t be livable for humans, or many other animals, in a short period. It’s already getting to the point where many previously inhabitable places aren’t anymore, and that’s with some amount (not enough) of harm reduction.

Let’s reduce this to just you, for an example. Let’s say you’re driving your car. Do you have an obligation to attempt to not harm others with your vehicle? Should you try to not run over children, for example? If so then what’s the difference to the original question? If not then there’s something wrong with you.