Al-Jabi / Flickr
Our planet is crossed by fiber optic cables, which are being used to build a gigantic map of the underground world. This system may be crucial for the prediction and mitigation of future seismal damage.
According to an estimate cited by, more than 4 billion kilometers of fiber optic cables Serpenty underneath and between cities.
Usually we don’t think much about this physical network. We only worry about receiving calls and surfing the internet. But, increasingly, the cables themselves are becoming a valuable source of information about the planet.
In Istanbul, for example, these fibers reveal vital information on the form of protect people and infrastructures against future earthquakes.
Under the streets of the Turkish city, a fiber optic cable pulsates with laser light. Until recently, this stretch of the “information highway” was inactive. But a group of investigators has joined to resurrect this system.
But this system has more applications. In London, the system allows researchers to measure the Underground Tinnitus of Agitation; in Iceland it is possible to follow the crash of volcanoes; In addition, it also allows map the upper zones of manto of our planet.
By a more “transparent” land
“The general objective is a Transparent land“Said Jonathan Ajo-Franklin of Rice University in Texas to New Scientist, adding that“ these fibers revealed Information that can save lives“.
Most telecommunications networks are full of unused cables, installed in anticipation of future traffic.
But just over a decade ago, seismologists realized that they could reuse fiber optic cables to monitor underground tremors. This would be a cheap way to widen the coverage of the existing seismometer networks, whose installation and operation are expensive.
The high spatial resolution obtained with the optical fiber could also create a much more detailed image of the subsurface – At least the little depth – than the one that can be obtained with the seismometers that measure the tremors in a single point.
This gave rise to the field of Distributed Acoustic Detection (DAS)referring to the fact that the cables allow to measure acoustic waves at many points along their length.
The oil and gas industry was a pioneer in the use of DAS; Already in 2009, the industry was testing ways to monitor shakes in the wells, passing a fiber optic cable with the drill.
The approach was quickly adopted for a wide range of applications, from the tracking of animal movement through your steps until the observation of changes in soil moisture by measuring the speed of the waves that move through the soil.
Under our cities …
New cables surround Athens and cross the Greek capital in a large X, which should allow scientists to create a detailed and three -dimensional map of the city’s underlying geology and risk.
“For a seismologist, this is a dream geometry,” he told New Scientist, Andreas Fichtner From Eth Zurich, Switzerland.
As the same magazine unravels, a group of researchers at the University of Southampton, UK, is also preparing a even greater projectusing a dark fiber network that connects Southampton, London and Cambridge.
“No one made a continuous acquisition of large -scale data in really large cities like this,” praised the leader of the work, Rafael Mestre.
Although these areas are not prone to earthquakes, data may have a number of applications, from the identification of leakage in underground conduct to the evaluation of the stability of the foundations of buildings.
Largest Underground Map
However, other US researchers are using these networks to penetrate the planet’s depths.
The US Geological Service (USGS) recently used a dark fiber of 100 kilometers in California to cartograph the border between the crust and the Earth cloak with an unprecedented detail.
The monitoring of shaking in this area may allow researchers to map this complex region with more detail, clarifying how it generates such strong earthquakes.
“It’s exciting to think of getting images of the earth with a much higher resolution. We are trying to use this fiber to make some interesting science,” James Atterholt from USGS.
Measuring these earthquakes in the midst of the internet signals could, in fact, widen our view of the interior of the planet worldwide. It will be a huge step in directed to a truly transparent land.
Privacy concerns
This extraordinary sensitivity raises, however, concerns about privacy and vigilance. Fibers are so sensitive that they can, in theory, be used to detect steps or even voiceswarns Rafael Mestre.
“These networks will be used and people don’t even know it,” he says.
Cables are focused where people live, so they are not useful in more remote places. And gaining access from telecommunications companies and governments can be a headache, found Fichtner in turn.
In fact, “this extraordinary sensitivity raises concerns about privacy and surveillance“The expert warned.
