We've already seen that Twitter can be a useful predictor of stock market swings, a movie's box-office sales, and even outbreaks of swine flu. But the earthquake last week revealed yet another interesting possibility: Twitter activity managed to show how intense the earthquake actually was, up and down the East Coast. (I know, I know, all you want to talk about this morning is Hurricane Irene. Tough luck, brah. Good infographics take time to produce.)
This wasn't really what the data viz team at SocialFlow set out to find — and indeed, they don't seem to have quite noticed this message within the data. But their infographic is really something to behold. It shows tweets spreading across the country in the 80 seconds immediately after the earthquake hit; the rate of twitter activity is color-coded from red (most intense) to blue (middling intense) to green (least intense).
And here is how the Twitter activity played out at 10, 30, 50, and 80 seconds (note the expanding ring, which shows how far the earthquake's shock wave has traveled):
Notice anything there? No? Well, let's just think through what you'd expect to see: As the earthquake's shock wave spreads, you'd think that each metro area would be reacting with the same sort of intensity you saw at its epicenter in Virginia. After all, each successive ring of people is getting freaked out all fresh. But that's not happening. As the earthquake travels along, the intensity of people's reactions to it is actually decreasing. What on earth is going on here?
It seems that somehow people further and further from the epicenter are finding the earthquake less and less interesting. The most obvious reason is this: For one, the feeling of the earthquake isn't quite as dramatic, and the damage it's causing isn't as severe (if it even caused any damage at all; New York, for example, was totally unharmed). So people are tweeting less about earthquake when it feels less threatening. Let me repeat that: They're tweeting less when the earth quake feels less threatening. That sounds rather innocuous, but that single insight allows you to see the chart in a totally different way. For one, the map above actually doesn't just show the spread of earthquake-related tweeting, but actually the emotional impact and physical damage. Human beings, processing the information about the earthquake, are basically acting as sensors, as SocialFlow elegantly puts it.
In the future, this realization could be applied in potentially remarkable ways. How predictive could Twitter be of a natural disaster's impact? Could FEMA, for example, use Twitter maps to survey for damage and find people in distress? And how granular can this data get? Hopefully, we'll see some data soon as it applies to Hurricane Irene...
[The guys over at SocialFlow emailed to say that color in the charts above actually just indicates the distance a tweet was from the epicenter. Meaning that much of my interpretation is null and void, so I've marked it up with a strike-through. They did, however, point out that I was on the right track in pointing out emotional intensity, albeit in a slightly odd way: Those who experienced the earthquake wrote much different sorts of tweets than those who did not. 53% of Seattleites, for example, used exclamation points in their tweets about the earthquake, as opposed to 94% of Washingtonians.—CK]
[Check out the interactive version here. Warning: It's a very heavy download.]