Many kilometers from the west coast from America, a submarine cable connects Los Angeles, California with Valparaiso, Chile. Stretched from one end to the other, it is equal to four-fifths of the diameter of the Earth. The cable is made of fiber optics; is a lifeline for data transmitted between the two continents. But according to new research, the cable could easily perform a dual function: mitigating the disastrous impact of earthquakes and tsunamis.
The results come from an interdisciplinary collaboration between geophysicists and network engineers who analyzed the disturbances in the polarization of light transmitted through cables. A patent has been filed in connection with that of the team work on this topic, published Wednesday in the journal Science.
“There are scientific and social implications here,” said Zhongwen Zhan, lead author of the new paper and geophysicist at the California Institute of Technology, in a video call. “Most of our geophysical sensors for detecting earthquakes and studying the appearance of the Earth’s interior are on land, but many of the most important geological processes take place in the ocean. We use pre-existing cables in the ocean for a relatively scalable way to detect earthquakes. We believe that in the future we will be able to use them for early earthquake and tsunami warnings. ”
In the relentless online world we live in, where movies shot a century ago can be transmitted at the touch of a button and you can talk face to face with someone on the other side of the planet, fiber optic cables carry an informational burden. Such submarine cables like Google’s “Curie” cable constantly transmit huge amounts of data at breakneck speed to keep the world connected.
The inevitable imperfections of cables mean that the polarization of light varies as data moves through them in both directions. Other disturbances, such as temperature fluctuation and human activity, can become even more confusing with cable polarization. But in the depths of the sea, temperatures are relatively constant and there are rarely people. This means that when a seismic wave ripples through the environment or passes a high ocean level, it is visibly detectable by the way it deforms the submarine cable.
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Since seismological seabed research it is time consuming and expensive, the fluctuations of reading the polarization of such deep cables are a cheap and timely alternative, say the study authors. There are a lot of submarine cables to read such data. While the Curie cable measures about four-fifths the diameter of the Earth, total submarine cable network could orbit the planet 20 times. Among half a century of other geophysical events recorded by the team, the Curie cable detected the magnitude 7.1 earthquake that struck Oaxaca, Mexico, in June last year.
When the team first recognized a cable signal disruption and managed to align it with an earthquake, “it was not expected at all,” Zhan said. “No one has ever detected an earthquake watching a telecommunications signal itself.”
During the team’s observations, they were able to recognize 20 earthquakes and 30 ocean waves. Importantly, the team is not yet able to detect the epicenter of any seismic event – the cables only lift the disturbance – but Zhan said that along the way, it might be possible to triangulate the epicenters of the earthquake by analyzing the disturbed polarizations on different cables.
“I think this will turn the way we look at the oceans as seismologists,” said William Wilcock, a University of Washington seismologist who is not affiliated with the new work, in a phone call. Wilcock recently wrote a Perspectives in Science article about the work of Zhan’s team. “In my area, there is a lot of concern about the Cascadia offshore subduction zone and a lot of thought has been given to how to develop the infrastructure offshore to improve our monitoring. Doing this with dedicated systems means hundreds of millions of dollars. But being able to potentially use commercial cables to do at least some of this is a huge advantage to go further. ”
It remains to be seen whether the method of listening to the Earth is largely adopted by the telecommunications industry. What is certain is that this team has shown that we can listen to the light, using the by-product of your game Call of Duty or sending family photos to spy on the seismic activity of the planet, maybe it prepares us better for anything small or very, very big will continue to come.