How technology is helping us map earthquakes faster than ever
In the aftermath of the earthquake in Nepal聽on Saturday, technology has stepped into the information gap to help map the terrain for first responders using GPS, satellite, and open-source data.
Researchers at the US Geological Survey, the University of Iowa, NASA's Jet Propulsion Laboratory, and other groups expect to have the first post-earthquake images to come from satellites 鈥� due to pass over the affected regions聽on Tuesday聽morning, Nepal time 鈥� which they will use to create three-dimensional images of how the earth moved during the quake.
These images will aid in directing relief efforts effectively and conducting science that may lead to a better understanding of earthquakes and their early warning systems, says 聽a geoscientist at the University of Iowa who formerly worked with the聽USGS and who is assisting the agency on this work.
On Saturday, a 7.8 magnitude earthquake struck less than 50 miles from Kathmandu, leveling buildings and killing more than 4,000 people, according to reports.
The quake, the country's biggest in eight decades, triggered an avalanche on Mt. Everest, which killed at least 18 climbers. Tremors were felt in India, Tibet, and Bangladesh.
Soon after the quake hit Nepal, those on Twitter and other social media networks began searching for reports from those on the ground in affected areas in order to help gauge the damage and assist relief efforts to the area.
One effort, The 聽鈥渁pplies the principles of open source and open data sharing for humanitarian response and economic development,鈥澛燼ccording to its website.
The team asks those living in the affected areas to help out by聽聽which buildings are damaged, which are still standing, and where fissures and other quake damage are located.
According to Prof. Barnhart, it鈥檚 as important to report a building that鈥檚 still standing as it is to report one that鈥檚 gone down, so we can assess the infrastructure.
Barnhart explains that the data used to map a quake is collected from several different sources.
聽readings can, within 30 minutes, report a quake's location, magnitude, impact, and potential monetary damage estimates. A seismograph, which measures the movement of the earth, consists of a ground-motion detection sensor, called a seismometer, paired with a recording system.
Publically accessible聽聽platforms involve people in the affected zones reporting damaged and undamaged buildings, fissures and other damage.
Then there is local聽聽station data, which, when combined with satellite data, is called聽.
鈥淲e鈥檙e still trying to obtain as much of this information as possible,鈥� he says. 鈥淭he GPS data is run by various universities internationally, some are recording in real time, some are not so right now we鈥檙e waiting for that data to come out.鈥�
At the moment, some of that data still has to be 鈥渢elemetered,鈥� or sent from the GPS server on the ground so that the USGS can access it.
鈥淚n a case like this I think many of those networks were telemetered through Kathmandu,鈥� he says. 鈥淚t鈥檚 tough right now, because so much of the infrastructure in the country has been damaged so severely and the data is dependent on the infrastructure to get out.鈥�
USGS is also using remote sensing, a combination of satellite data from optical satellites as well as radar satellites, according to Barnhart.
This is not the kind of GPS data that a source such as Google Earth could provide, he says, 鈥淔or GPS data to be useful it has to be very close to the earthquake, because it鈥檚 sensing the actual physical permanent ground displacement caused by the earthquake.鈥�
鈥淭he GPS, it has to be right in the zone of the earthquake itself otherwise it doesn鈥檛 record anything,鈥� he says.
Meanwhile, seismometers can be distributed globally because they鈥檙e sensing the seismic waves that travel through the entire planet.
The term for using of GPS to accurately measure, map and understand the Earth is called geodesy, and it鈥檚 playing a significant role in making sure limited resources go to where they are most urgently needed in Nepal this week.
Barnhart says it is also the next step to take in early warning systems here in the United States that would allow for a quicker shutdown of schools and nuclear facilities in a seismic event, tsunami, or landslide.
鈥淩ight now a lot of work is going into actually using these geodetic networks in earthquake early warning,鈥� he says. 鈥淯ntil now earthquake early warning has been traditionally within the realm of seismology only. But there can be a lot of ambiguity when an earthquake starts to happen 鈥� from a seismological perspective.鈥�
Barnhart concludes, 鈥淭he nice thing about geodesy is that if you have several GPS stations along a fault and you can see them unrolling in real time and they move one or two meters, you don鈥檛 even need to know the magnitude of the earthquake is. You know a big earthquake just happened. So a lot of work is being done right now by researches to incorporate GPS into early warning systems.鈥�
