With services like Twitter and Facebook ready at our fingertips, the internet is making it possible for people to share more than ever about their personal experiences. In some ways it may not be obvious how such information might be useful to scientists – like status updates about running out of orange juice or having to wait in line at the store. But this collection of information about the behavior and experiences of millions of people, often updated as events are happening, has resulted in an important new resource for many scientists. Researchers have even studied Facebook statuses and tweets to understand the effect of public mood swings on the stock market and how people are treating their own tooth pain.
One set of scientists have found this new resource of up-to-the-minute information from around the world particularly useful: the scientists who study earthquakes.
Traditionally earthquakes are studied using scientific instruments like seismometers placed all over the world. These instruments measure the movement of the Earth’s surface in precise ways that help us understand which faults have moved, where, when, and by how much.
But with earthquakes, there are many important things to understand besides the precise movement of the ground. Scientists, rescue teams, and people like you want to know where the shaking was the strongest and how much damage occurred. They also want to know when an earthquake is happening as quickly as possible to try to prevent people from getting hurt.
When an earthquake happens, the energy released by the movement of the Earth’s crust takes the form of seismic waves. The strength and direction of these waves are responsible for the shaking that you see during an earthquake. As these waves get farther and farther away from the starting point of the earthquake, they get weaker. But these waves can cause shaking hundreds of miles away in only a few minutes.
In the last eight years a rather unexpected new source of information started providing amazing details about earthquakes almost as quickly as they were happening: Twitter.
Twitter is a service that allows users to send and receive short messages called "tweets" to groups of people using the internet. When an event like an earthquake happens, thousands tweet about it so quickly that people have received tweets about an earthquake before feeling the shaking from the earthquake itself.
For decades scientists have been trying to develop tools for warning people at risk about earthquakes in their area. To do this, the scientists would need to be able to recognize that an earthquake is happening and communicate this risk to the people in that area as quickly as possible – ideally before the seismic waves reach them. While this may not be possible for those closest to the earthquake, in the seconds and minutes before the waves reach new areas there could be a chance. So the possibility that tweets could be warning people about earthquakes faster than the seismic waves drew a lot of attention.
According to Dr. William Barnhart of the US Geological Survey, scientists have tracked the words used in tweets to see if they could identify when and where earthquakes were happening. By monitoring all tweets being sent for words like “earthquake” and “shaking,” they are able to identify a likely earthquake in under a minute. Then, using the location information in these tweets, they can identify users in the affected area. This is especially important for areas that may not have many seismometers or other scientific instruments in place.
The US Geological Survey is just one of the organizations trying to do this. They use their Twitter Earthquake Dispatch (@USGSted) to notify their users when an earthquake has been detected. In November of 2013, Dr. Barnhart was actually watching television as an earthquake interrupted the Oklahoma-Oklahoma State football game. He said that this was one of the first earthquakes that was actually picked up by the twitter program before the traditional instruments in the area.
Another group of researchers tracked the appearance of earthquake-related tweets and compared them to the speed of seismic waves for the August 23, 2011 Virginia earthquake in the video below. While there are only a few cases where the tweets reached people before the shaking did, it is an important and unexpected result from a service meant to let people share status updates with their friends.
In addition to their Twitter Earthquake Dispatch, the US Geological Survey has been using the internet for years to gather information about earthquakes from the people who felt the shaking. Through their “Did You Feel It?” website, anyone can fill in a survey about their experiences. The scale for the survey does not require any sophisticated scientific equipment. "Instead," said Dr. Barnhart, "people answer questions about their own experiences to describe the intensity of the shaking in their area. Were their lamps swinging? Did any windows break? Did their furniture move around?"
These reports contribute to a measure called the “Macroseismic Intensity.” Rather than measuring the amount of energy released by an earthquake, like the well-known Richter Scale, this intensity focuses on the strength of the shaking based on the observations of the people who were actually there.
Scientists collect as much information as they can using scientific instruments, but measurements like the Macroseismic Intensity help in areas that may not have instruments at all. In 2003 in California more than 14,000 people reported their experiences on “Did You Feel It?” within a few hours of the earthquake. This allowed researchers to compare the effects of the earthquake from zip code to zip code or even neighborhood to neighborhood – a much closer look than the seismometers in the area would have allowed.
Dr. Barnhart explained that this information is also used by government organizations to decide whether help should be sent out after an earthquake. This might be food and water for isolated people or even search and rescue teams in areas with very severe damage.
Even if people near an earthquake don’t feel any shaking at all, it is important for scientists to know. These surveys may not be the response from the first few minutes – like on Twitter – but the participation of people like you in the first few hours and days helps scientists decide how to best study the earthquake in the next months and years.
You can also access the information from these surveys yourself through the USGS website. You can find the maps of shaking from past earthquakes, see what earthquakes are happening around the world every day, and even get an email or text message sent to you every time there is an earthquake. This is just another reminder that new approaches to science can come from unexpected places. Anyone – even you and your teachers, classmates, or families – can contribute valuable information to help scientists study important events like earthquakes.
Bollen, J, Mao, H, and Zeng, X (2011) Twitter mood predicts the stock market. Journal of Computational Science. 2(1) doi:10.1016/j.jocs.2010.12.007
Earle, P, Guy, M, Buckmaster, R, Ostrum, C, Horvath, S, Vaughn, A (2010) OMG Earthquake! Can Twitter Improve Earthquake Response?81(2) p. 246-251doi:10.1785/gssrl.81.2.246
Heaivilin, N, Gerbert, B, Page, JE and Gibbs, JL (2011) Public Health Surveillance of Dental Pain via Twitter. J Dent Res. 90(9): 1047-1051. doi: 10.1177/0022034511415273
Konkel, F (2013, February 6). Tweets give USGS early warning on earthquakes. Retrieved from http://fcw.com/Articles/2013/02/06/twitter-earthquake.aspx?Page=1
Wald, DJ and Dewey, JW (2005 March) Did You Feel It? Citizens Contribute to Earthquake Science. Retreived from http://pubs.usgs.gov/fs/2005/3016/
https://www.youtube.com/watch?v=XJ1EQbmJ_LQ from Harvard's Harvard’s Complexity and Social Networks blog