Earth sciences: Finding faults using broadband

Fibre-optic cables have been used to detect seismic signals and image geological faults, reports a study published in Nature Communications this week. The findings demonstrate that broadband telecommunications networks could be used in the future to locate and assess faults, and that the cables could be used as an alternative to seismometers.

Traditional seismic networks may cost hundreds of thousands of dollars to operate and maintain, but are crucial in earthquake prone areas. However, fibre-optic cables used for telecommunications have been proposed as a low-cost method to monitor seismicity.

Philippe Jousset and colleagues set up an experiment in Iceland where fibre-optic cables are transformed into a series of sensors to record natural and man-made seismic waves. The sensors quantify strain by measuring very small changes in the length of the fibre-optic cable as seismic waves pass through.The authors found that the cables not only recorded seismic signals, but were also able to resolve in detail the surrounding faults and other geological structures at depth.

Although fibre-optic telecommunication networks may be able to be used in earthquake hazard monitoring, the team caution that more development will be needed.