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About 70% of Earth's surface is covered by water, and almost all seismic detectors are on
land.
With the exception of some expensive battery-powered sensors that are sunk to the ocean floor and subsequently retrieved and an array of several nearshore detectors connected to land, seismologists are unable to monitor earthquakes that ripple the ocean floor and potentially create tsunamis
.
But this week, a technique described online in the journal Science promises to use more than 1 million kilometers of undersea fiber-optic cables covering the world, and by looking for tiny changes in the light signal propagating along the cables, scientists can detect and potentially locate earthquakes
.
The technology requires only a little more lasers than at both ends of the cable and is able to access a fraction
of the cable's bandwidth.
It is essential that it does not require the modification of the cable itself, nor does it affect its day-to-day use
.
The method "could be a game-changer," says Anne Sheehan, a seismologist at the University of Colorado, "and more observations from ocean areas could fill some of the considerable gaps
.
" ”
The innovation began with an unexpected discovery, said Giuseppe Marra, a metrologist at the National Physical Laboratory in Teddington, UK, who is responsible for connecting
atomic clocks at the European laboratory.
He is testing connections on a 79-kilometer buried cable from Teddington to Reading, England, and relies on a stable, resonant laser loop
.
Vibrations near the cable, even traffic noise from above, can bend
unconsciously.
This shortens or lengthens the travel distance of the light to be smaller than the width of a human hair, causing the resonant beam to deviate slightly from phase
.
Marra is used to this background noise
.
But when he looked back at the data from October 2016, he saw more than just the average noise volume
.
The local effects
of the magnitude 5.
9 and 6.
5 earthquakes in central Italy later this month proved to be present.
"It's a fairly obvious moment," said Marra, who realized that the noise pointed to new ways
to detect earthquakes.
Marra said the new technology is sensitive enough to work across ocean basins thousands of kilometers wide to monitor marine earthquakes and related environmental changes
at low cost.
About 70% of Earth's surface is covered by water, and almost all seismic detectors are on
land.
With the exception of some expensive battery-powered sensors that are sunk to the ocean floor and subsequently retrieved and an array of several nearshore detectors connected to land, seismologists are unable to monitor earthquakes that ripple the ocean floor and potentially create tsunamis
.
But this week, a technique described online in the journal Science promises to use more than 1 million kilometers of undersea fiber-optic cables covering the world, and by looking for tiny changes in the light signal propagating along the cables, scientists can detect and potentially locate earthquakes
.
The technology requires only a little more lasers than at both ends of the cable and is able to access a fraction
of the cable's bandwidth.
It is essential that it does not require the modification of the cable itself, nor does it affect its day-to-day use
.
The method "could be a game-changer," says Anne Sheehan, a seismologist at the University of Colorado, "and more observations from ocean areas could fill some of the considerable gaps
.
" ”
The innovation began with an unexpected discovery, said Giuseppe Marra, a metrologist at the National Physical Laboratory in Teddington, UK, who is responsible for connecting
atomic clocks at the European laboratory.
He is testing connections on a 79-kilometer buried cable from Teddington to Reading, England, and relies on a stable, resonant laser loop
.
Vibrations near the cable, even traffic noise from above, can bend
unconsciously.
This shortens or lengthens the travel distance of the light to be smaller than the width of a human hair, causing the resonant beam to deviate slightly from phase
.
Marra is used to this background noise
.
But when he looked back at the data from October 2016, he saw more than just the average noise volume
.
The local effects
of the magnitude 5.
9 and 6.
5 earthquakes in central Italy later this month proved to be present.
"It's a fairly obvious moment," said Marra, who realized that the noise pointed to new ways
to detect earthquakes.
Marra said the new technology is sensitive enough to work across ocean basins thousands of kilometers wide to monitor marine earthquakes and related environmental changes
at low cost.
