Fiber Optic Cables Get Additional Functionality As Seismic Detection Becomes Advanced

The latest application in the hair-thin fiber optic cables is distributed acoustic sensing (DAS) – A method which detects the tiniest movement flaws for collecting seismic data and warn of an impending earthquake. This technology works on the premise of installation of thousands of sensors along tens of kilometers of fiber optic cable. A device at one end of the cable sends laser pulses and collects and measures the intensity of the “echo” at the other end as it is being reflected back by internal fiber flaws. Any change in temperature, strain or vibration caused by an undetected seismic wave will be reflected back by the upcoming wave with a difference in size, intensity and phase of the laser pulse.

Seismologists can then detect the intensity of the earthquake by studying the difference between the two waves. The difference noted between the original wave and the reflected wave can be as minor as a few power to tens of nanometers. The sensitivity of DAS equipment has improved remarkedly over the years which opens up the technology to bran new opportunities. Their increase in performance can make them highly viable for working in dangerous environments – especially in places where setting up seismic activities is highly probable.

Additionally, researchers can also tap into the already laid groundwork of optic fiber that has already been completed. This technology is being developed for monitoring seismic activity on highly unconventional places like the surface of the moon or some other planet where high temperature and radiation will render the traditional functioning of devices completely useless. Scientists are already implementing DAS in order to probe thawing and freezing cycles in permafrost conditions on glaciers in order to better monitor and chart the dynamic motion of the flow of ice w.r.t the bedrock on which it rests upon. The current range of DAS systems is limited to 20 kilometers, however, this range is expected to go up significantly as the applications outweigh the developmental cost.