Fiber Optic Cables May Also Work As Early Earthquake Detectors


A new technique has reportedly been devised by scientists to make use of fiber optic networks as sensors for earthquake. This is the first time that a network is being used as a sensor for this purpose, though fiber optical cables have been used to relay high-speed data in a reliable manner for the past many years.

Using Fiber Optic Cables To Detect Earthquakes

According to a report, the new system has been in the process of development more than a year now by scientists from Stanford University. To test the technique, a 4.8km testing loop was set up at the university to measure the Earth's vibrations and disturbances.

The researchers also ensured that the vibrations being recorded did not overlap with other sources — like those coming from ambient and traffic disturbances. Since the network's setup in September 2016, the research team has been able to record 800 events that included the devastating earthquake that hit Mexico on Sept. 19 as well as the rumbles that followed the quarry explosions in California this year.

The fiber optics cables network can also pick up the differences between the two kinds of waves caused by earthquakes — namely the P and S waves. Incidentally, P waves are those that have a faster rate of travel whereas S waves result in more destruction. Understanding the difference between the two types of waves is an important and integral part of an early warning system, according to the researchers.

"People did not think this would work," project associate Eileen Martin said. "They always assumed that an uncoupled optical fiber would create too much signal noise to be useful," she added.

The System Makes Use Of Loose Cables Encased In Plastic Pipes

This is the first time when cables have been used to detect seismic movements without balancing and stabilizing the cables using pre-installed pipelines or encasing them in cement. Furthermore, the project simply makes use of loose cables covered in plastic pipes in a manner similar to general communications cables.

According to a report, the technique can be a success because there are inherent flaws or impurities in optical fibers and each of them can be worked as a sensor. Moreover, the technique is getting better and giving sharper results in higher resolutions.

Lead project scientist Biondo Biondi feels that while the images captured by dedicated seismic instruments are crisper and more accurate than virtual ones, they are quite expensive. Biondi says this is the reason why it becomes expensive to afford earthquake networks continuously. At present, the research team is getting ready to examine the new technique over a broader network sometime next year.

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