Hi - there are a couple ways to do this. It all depends on which channel you want to use.
If the alerts are on a web page or mobile app, you can use Geo targeting based on the web site visitor's location.
If alerts are pushed to known customers via, say, an email or mobile push notification, then you'd build a segment for all the customers you want to reach and use geo field as part of your criteria. This assumes you have country, state/province, and/or city fields in your customer data.
If you'd like to share some additional details about the scenario you are working on, we'll try to help.