The present invention provides a method and system for disseminating urgent public announcements over an IP-based network. One or a plurality of Internet- or Intranet-connected servers receive and store data identifying particular geographic locations to current announcements. The servers identify IP addresses of users making URL requests or requests for target applications (an access point by which a network-connectable mobile device is connected to an Internet- or Intranet-connected server), determine a location for each user from the user's IP address (or access point), and determine whether an IP address (or access point) of a user corresponds to a location for which an announcement has been posted. If the user is identified to a location for which a current announcement is available, the announcement is displayed to the user.The announcement may be displayed by redirecting the user to a web page containing the announcement. Alternatively, the announcement may be displayed in a pop-up window or in a banner on a web page requested by said user. A banner displaying such an announcement may incorporate a link to permit the user to click through to a web page containing a more detailed version of the announcement.