Source: http://www.xkcd.com/723/
The above comic pretty much happened when a 5.8 earthquake hit Virgina in 2011, as people up and down the East Coast received tweets about an earthquake seconds before feeling the earthquake for themselves.
- See http://articles.baltimoresun.com/2011-08-23/news/bs-md-earthquake-20110823_1_downtown-baltimore-maryland-geological-survey-quake and other news sources for reaction to the earthquake.
- See also http://www.hollywoodreporter.com/news/earthquake-twitter-users-learned-tremors-226481 and http://blog.xkcd.com/2011/08/24/earthquakes/ for discussion about Twitter reaction to the earthquake.
It also inspires the obvious word problem for Algebra I students.
When an earthquake hits, seismic waves travel at about 5 meters per second. Suppose that Alex tweets about the earthquake 30 seconds after feeling its seismic waves. The tweet travels at about 200,000,000 meters per second. How far away does someone have to be from Alex to receive the tweet before also feeling the seismic waves?
Mean Green Math 