This Smart New Tech Can Turn Underwater Cables Into Earthquake Detectors


The project aims at greatly speeding up the detection of devastating tsunamis, and for that, Caltech seismologists and Google optical experts have joined hands. The new method will turn operating submarine communication cables into earthquake detecting tools without additional cost or adding any special equipment.

Two of the most destructive natural phenomena are earthquakes and tsunamis, which, if bad, can destroy whole cities in seconds. Unfortunately, even with all the technological advances, they are still quite unpredictable. With little to zero warnings, a shift in the earth’s crust or an undersea landslide can cause havoc and death of thousands of people in a single moment.

To fight this, scientists and researchers have been putting in extensive efforts over the past many years to form an early warning system. For this, scientists have come up with one considerable solution of turning the network of extensive underwater communication cables into a massive prediction system.

However, most people think that the world is an integrated place due to the hyper-connected wireless networks, where in actuality, 99 percent of all overseas data transmission is done through undersea cables. Other than the high polar regions, the oceans are filled with a bundle of network transmission wires crisscrossed around the coasts.

In a contradicting view, land seismometers and ocean seismic networks such as the Deep-ocean Assessment and Reporting of Tsunamis (DART) system, which run on the US National Oceanic and Atmospheric Administration’s National Data Buoy Center, can develop only incomplete and remote coverage of ocean seismic events like tsunami’s and earthquakes.

The significant problem is that the shock waves travel at the speed of sound, making that there is little to zero warning when a Tsunami or an earthquake is about to take place. However, if submarine cables could catch these events’ happenings, it would be far more effective given that they are much closer to the source, allowing them to generate considerable warnings at a swift speed.

The idea to attach the submarine cables with an early warning system isn’t new. However, the previous ideas involved installing complex and special equipment or inoperative cables, making it an impossible task. The new idea uses Caltech/Google method, which deploys fiber-optic cables that telecom companies have been using since the ’80s.

As part of their ordinary application, the laser pulses used to transmit numerous channels of data are polarized. They are routinely monitored as the pulses reach the other end. In case if the equipment is working fine, the laser pulses will stay polarized like in routine. However, in case of some error or malfunction, their polarization change. A simple explanation for this is “seismic events could be monitored on a live cable with standard equipment.”

The researchers’ team was able to assess the polarization of the pulses along the cable about twenty times per second by making changes to the curie cable, which runs along the west coast of south and north America and from Los Angeles to Valparaiso. The values remained constant, given that there were no seismic movements. However, if a movement occurs, the values would change, letting the team know of a possible tsunami or an earthquake.

During the last nine months, 20 moderate to large earthquakes have been detected along the cable, with the most significant one marked at a 7.7 magnitude at rector scale.

Finally, a tech would be developed, configured with algorithms to allow the cables to be monitored autonomously. And also to ignore the disturbances caused by underwater creatures and moving ships.

“This new technique can really convert the majority of submarine cables into geophysical sensors that are thousands of kilometers long to detect earthquakes and possibly tsunamis in the future,” says Zhongwen Zhan, assistant professor of geophysics. “We believe this is the first solution for monitoring seismicity on the ocean floor that could feasibly be implemented around the world. It could complement the existing network of ground-based seismometers and tsunami-monitoring buoys to make the detection of submarine earthquakes and tsunamis much faster in many cases.” 


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