Federal, provincial, and territorial emergency management agencies have lots of non-social media ways of telling people to get out of Dodge, but for smaller updates on a situation that don't need an alarm going off on everyone's phone in a huge area social media and news are more reliable for reaching a large number of people. People don't check government websites often enough, but they check twitter and Facebook a lot, and it's repeatedly shown to be the method that gets the most attention from affected people.

A lot of these smaller updates are stuff like status of people's homes, updates on the wildfire and suppression efforts, options for evacuees, reminding people to stay out of town, etc.

Actual emergency warnings that need urgent action result in every phone in the region blaring like they're waking the dead. Those do not rely on the benevolence of foreign corporations.