#earthquake: Twitter beats government sensors for reporting seismic shocks
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The fastest earthquake alerts come from social media networks, not the U.S Geological Survey's seismic underground sensors, it has been claimed.
Researchers from the U.S Geological Survey analysed tweets containing the word 'earthquake', and found reports were online within 1 minute.
Researchers say using their traditional seismometers, which monitor ground motion it takes 2-20 minutes to precisely locate an earthquake and judge its size.
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The ultimate earthquake detector? Researchers from the U.S Geological Survey analysed tweets containing the word 'earthquake', and found reports were online within 1 minute - compared to 2-20 minutes with existing instruments.
HOW IT WORKS
Twitter has 255 million active users worldwide, and the USGS, using a software tool, tracks the word "earthquake" in languages ranging from Tagalog to Spanish.
The Twitter conversation ranged from 600 tweets per minute following a magnitude-5.8 earthquake offshore of Java to 4,000 tweets per minute after the 2011 Virginia earthquake to more than 10,000 tweets per minute after the massive 2011 Tohoku earthquake in Japan.
'Frequently, it's the first indication of a widely felt event,' said Paul Earle, director of operations for the USGS National Earthquake Information Center, who presented the findings at the Seismological Society of America's annual meeting in Anchorage, Alaska.
On average, in the past 10 months, the USGS software tool detected 19 earthquakes a week, or about two to three per day.
According to Livescience, about half were detected in less than a minute, and 90 percent in less than 2 minutes.
The weakest was a magnitude-1.4 quake, and the strongest was a magnitude 8.2.
The service has set up a special account, @USGSted to monitor the activity and alert people.
'The account and @USGSBigQuakes will produce about one tweet per day, however, aftershocks following major earthquakes can greatly increase this number,' the USGS said.
'The USGS Tweet Earthquake Dispatch' distributes alerts for earthquakes worldwide with magnitudes of 5.5 and above.
'In addition to the seismically derived parameters, the alerts also include the frequency of tweets in a region surrounding the event that contain the word " earthquake" or its equivalent in several languages.'
However, the USGS said that with a 10 percent error rate, a Twitter app won't replace official earthquake instruments.
Twitter itself is also working with Stanford University to develop a system to monitor social networks for details of earthquakes.
Twitter has 255 million active users worldwide, and the USGS, using a software tool, tracks the word 'earthquake' in languages ranging from Tagalog to Spanish.
The Twitter conversation ranged from 600 tweets per minute following a magnitude-5.8 earthquake offshore of Java to 4,000 tweets per minute after the 2011 Virginia earthquake to more than 10,000 tweets per minute after the massive 2011 Tohoku earthquake in Japan.
'At Twitter, we know that Tweets can sometimes travel as fast as an earthquake,' the firm said.
'We were curious to know just how accurate such a correlation might be, so we collaborated with Stanford researchers to model how Tweets can help create more accurate ShakeMaps, which provide near-real-time maps of ground motion and shaking intensity following significant earthquakes.'
At twitter, researchers analysed the 2011 Japanese Tohoku earthquake, and mapped (a) the number of geo-tagged Tweets containing an earthquake keyword per minute after the event, (b) the distance between each Tweet and the epicenter as a function of time, and (c) a map showing the number of Tweets, where the star represents the epicenter location.
WHAT MAGNITUDE MEANS
Magnitude 1 and 2 – Not felt by people, detected by instruments.
Magnitude 3 – Silght tremor felt by people indoors, likened to a passing lorry.
Magnitude 4 – Can crack walls, disturb trees.
Magnitude 5 – Moves furniture, damages poorly built buildings.
Magnitude 6 – Moderate to major damage, chimneys and walls collapse.
Magnitude 7 – Major damage to all buildings, ground cracks, landslides can occur.
Magnitude 8 – Total destruction, waves can be seen travelling through the ground.
The maps are used by federal, state and local organizations, both public and private, for post-earthquake response and recovery, public and scientific information, as well as for preparedness exercises and disaster planning.
When an earthquake happens, a ShakeMap is typically produced in a matter of minutes using a combination of recordings, a simple ground motion prediction equation, and geological site correction factors.
As time progresses, the ShakeMap is continually updated as new information becomes available, including 'did you feel it?' data — qualitative first-hand accounts of the earthquake collected via online surveys.
'To help improve the accuracy of ShakeMaps, we used all geo-tagged Tweets around the world containing the keyword 'earthquake' or 'tsunami' in several languages that occurred in the first 10 minutes following Japanese earthquakes of magnitude 6 or greater from 2011 to 2012,' said Twitter.
It plans to release more details of the system at a conference in July.
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