Most social media now comes with location tracking, meaning you can share where you are sharing things from as you send out your social media messages. This is important because your Tweets will show up in the locality you are in. but more than that, you can search for things in Twitter that are happening in your area. In fact, if you go to the advanced search function on Twitter you can specify keywords, locations and even dates.
You could then show your support as a business by sharing the Tweets you find, or commenting on the event. You could also find out if the event is close enough to go to in person. Without a social network like Twitter, it would be difficult to get real time news about things going on in your specific location.
Many local businesses now have specific local charities that they follow on social media and champion through various channels. Another popular way to use Twitter is through sports club affiliations. As barriers to entry with promotion reduce by using tools like social media, businesses can put their resources to better use by going directly to the causes that they support.