So a big national or international story occurs. Your news director wants some local connection. Social media can help you find someone related to the story. For example, let’s think about the recent explosions in Turkey. You can search on facebook for people in your area who might have said something about Turkey.
As I started typing “Istanbul” in the main search bar at the top of the page I got a list of trending keywords. I clicked on that and then at the left (see below) I could filter it by location, so I put my hometown in, Syracuse. That pulls up posts from those who have tagged that they are in or near Syracuse. Here is what I found:
The first is a post by a Syracuse University professor noting that if his study abroad course had happened (apparently it didn’t) that students and faculty would be leaving from Turkey today. He might still be interesting to talk to as he probably has some contacts there.
I also searched for “people in Syracuse who visited Turkey” and that brought up some locals who had been there– see the screenshot at the left.
Most searches by place will look within 25 miles of the city you specify.
Twitter can also be helpful to search by 
hashtag or keyword and then by place. Go to the twitter search page, then click Advanced Search underneath the search box. On the advanced page at the right, note the circled portion shows where you can search by place.
I put in Turkey as a a keyword and Syracuse as the place. Up came a post in which a local man was talking today about being with some work colleagues from Turkey, and expressing concern for others in Turkey. So he and his colleague from Turkey would be worth contacting, as would his employer, who must have a branch office in Turkey.