How the USGS uses Twitter data to track earthquakes
At first, the USGS staff was a bit skeptical that Twitter could be used as a detection system for earthquakes – but when they looked into it, they were surprised at the effectiveness of Twitter data for detection.

October 8, 2015 at 12:38PM
via Digg https://blog.twitter.com/2015/usgs-twitter-data-earthquake-detection