Twitter spews an amazing volume of information into the world, yet its search function has never been precise. To be fair, it's faced far greater pressure to combat abuse, like it did releasing tools to cut trolls out of notifications last month. Today they're enriching that functionality even further, but just for Tweetdeck: Users creating search columns can now filter by location and date.
You'll have to create the column first before tweaking its area-specific settings and only unprotected tweets that are geotagged will show up. But that's still better than the erratic results when folks deign to include place names in their precious 140 characters.