Like Cell Broadcast just duplicates the SMS on carrier level?
Nah, Cell Broadcast has a lot less overhead since it does not have to do any routing or delivery confirmation and such. The load does not scale based on recipients which makes it far more reliable during an emergency.
Sorry, maybe I did "carrier replication" wrong - I used the word in a sense of "it is duplicated at the local cell by the towers", instead of getting "fed with 1mio receivers in region X by the telco servercentral HQ"
Im wrong, I guess?
Cell broadcast, depending on the emergency level set by the sender, also makes your phone vibrate until you read the message, and may also cause it to play a loud siren noise. Which is the sort of thing you want in a real emergency.