In Mexican Spanish, I've never seen the word "notificador" refer to anything other than a process server, i.e., a person appointed by the court to serve notices, summons, subpoenas, etc., but that's clearly not what it means here.

I have worked on a lot of Mexican oil company documents and I've never come across it in this context before, so I don't know of any standard English translation.

For me, the simplest solution would be just to translate it as "notifier," but if you don't like that, you could use "person required to give notification" [of the emergency] or "person required to announce" [the emergency].

"Broadcaster" as suggested above sounds a little odd to me here, just because it's so closely associated with media contexts.