Gaby Pena, on the Twitter blog:
Today, we’re launching Twitter Alerts, a new feature that brings us one step closer to helping users get important and accurate information from credible organizations during emergencies, natural disasters or moments when other communications services aren’t accessible.
This feature was actually launched a year ago in Japan, an initiative inspired by the massive use of Twitter during the catastrophe on March 11, 2011. The service saw a surge of people trying to get information, as LINE did.
Carrier also have a dedicated alert system in place, through a setting that your phone won’t have if you’ve not bought your phone in Japan.