The Great Shakeout will continue online for the next three weeks in an alternate reality game. Appropriately named Aftershock, the game was created by the Institute For The Future, the same folks that made SuperStruct.
Even if you’re not a Californian, I think it would be pretty easy to play. There’s a map and quake info on the website. And there look to be more than 300 players already. Want to join them?