I've been testing out the US Geological Survey's Earthquake & Tsunami warning feed on Twitter and in every case it's been the first warning of an earthquake and/or tsunami alert.

You can follow them at http://twitter.com/EQTW

If you have a Twitter client on your phone it can be a good mobile warning system. Most newer phones either have one or one can be downloaded. Check with your carrier or mobile shop for help.

http://www.twitter.com/

http://www.usgs.gov/

Hello

You can also sunscribe to these folks. No it is not my website and I don't get commission from them.

I am only a subscriber.

Check out http://www.tsunami-alarm-system.com/en/index.html