Study finds fibre-optic cables could detect geohazards early
Ordinary fibre-optic cables that power the internet could serve as an early warning tool for geohazards such as sinkholes, according to a new study led by researchers at Pennsylvania State University, WAM reports.
By using existing communication cables buried a few feet below ground on the university’s campus, the team devised a novel method to apply acoustic sensing technology. The approach, detailed in the Journal of Geophysical Research: Solid Earth, can detect fractured zones such as sinkholes hundreds of feet beneath the Earth’s surface.
The method involves a distributed acoustic sensing (DAS) interrogator developed by the researchers, which was connected to a four-mile stretch of pre-existing telecommunications fibre-optic cable. The DAS device transmitted light along the cable to capture acoustic signals across its length.
“We geoscientists often think of inputs such as everyday traffic as noise in the data. However, our research shows that the so-called ‘garbage noise’ is very useful,” said Tieyuan Zhu, associate professor of geophysics and corresponding co-author of the paper. “We can rely on these signals to spot geohazards in a way that’s much more affordable and effective than traditional methods.”
Conventional tools such as geophones, which measure ground density, are costly, labour-intensive and provide only a single data point. In contrast, the new approach transforms everyday traffic vibrations into seismic surface waves using cross-correlation, producing a detailed map of surface-wave speeds beneath the cable and generating a dense mesh of data points, the researchers explained.
Earlier, it was reported that quantum teleportation had been achieved using standard fiber optic cables.
