Istanbul has an early warning system. I was shown it briefly last June when I visited Kandilli Observatory...I think the system can show likely damage for different parts of the city for a particular quake...which would be useful for getting emergency responders out. You can probably Google this...they have a web site that explains the system (I think)...I'm not sure, but I suspect that they could get an early warning for an earthquake that starts at some distance on the North Anatolia fault and propagates towards the city. AS someone just posted here, Los Angeles could get a fairly long warning from a quake on the San Andreas near Palm Springs or Salton Sea that propagates northwest. Not clear from John's message whether there is any warning system in California for such a scenario....
Chris