Cities: Skylines

Ok Sketchy77 is correct that if you manually activate natural disasters in your city from the disasters' tab you can unlock this quickly. And it I'd true that using the forest fire option is the fastest way to get it. But, what is not said is that you need to click on the forest fire disaster where your people live; doing it outside the city where there are no people will not unlock this otherwise its an easy achievement. So place the aiming reticule over houses and buildings and people. Just use forest fire 10 times and boom it unlocks. Happy hunting!

The easiest way to do this is to manually activate natural disasters on your city. Go to the Disasters Tab in the menu, and the third sub menu along will have a list of disasters to unleash.

Most of the disasters have many minutes of delay between activation and them hitting. As such the best option is to use the "Forest Fire" option (Not the normal fire one), as it seems to activate immediately, do this 10 times and you have the achievement.