Google Earthquake detection by submarine cables

Google Earthquakes and tsunami detection with submarine cables :

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--- We know to built an accurate early warning system against the earthquakes the method of prediction and forecasting should he perfect with respect to time, location and magnitudes.

---- There is no 100% accurate method for earthquake prediction and forecasting.

---- Recently google experiment using one of his sunsea fibre optic cables showed that it could be useful for earthquake and tsunami warning systems around the globe.

---- Here, optical fibre cables that connects continents lies across the ocean floor used for internet and telecommunications. These cables carries data as pulses of light travelling at speed 204,190km/sec. The pulsating light encounters distortions as it travels thousands of km across the cables. At the receiving end, the light signals are detected and distortions are corrected by digital signalling processing. One of the properties of light that is tracked as part of the optical transmission is the state of polarisation (SOP). The SOP changes in response to mechanical disturbances along the cables and tracking these disturbances enables to detect seismic activity.

--- This idea was tested successfully and published(in 2018) for detecting earthquakes on both terrestrial and sunset links,  looking at phase changes using narrowband ultrastable laser. But links they used were short(535km for land and 96kn for subsea) and in shallow waters (200m deeps), limiting practical application of the idea. To be useful , they'd need to try this out on links that were much deeper on the ocean floor and covers 1000's kms distance.

---- Google tries this idea through his own submarine optical cables in late 2019 . They began monitoring SOP. They found SOP stable even signal travelled 10500km as ocean floor is quiet. 

---- Indeed ocean floor was too quiet, showing no SOP changes that could indicate an earthquake. On Jan 28,2020 Jamaica hit by an earthquake 7.7 magnitude , 1500 km away from submarine cables. A plot of SOP over time showed a pronounced spike at a time 5 minutes .similarly google detected multiple moderate size earthquake for example at east pacific rise, Valparaiso (Chile coast). The event produced a clear but short spike of SOP activity.

---- When a cable runs near the earthquake epicentre, a tsunami warning system that transmits data at the speed of light could communicate a warning to potentially affected communities in milliseconds.

--- millions of km of optical cables network already spread across the globe operated by governments, telecommunications providers and technology companies such as google. By collaborating with the global subsea cable community, weay be able to improve the world's ability to detect and search seismic activity around the world.

---- To create a robust earthquake monitoring system, researchers need advanced mathematics and data analytics, where advance computing system like google cloud can be instrumental. 

---- This method may be complimentary to already existing system such as precursor emissions, radon gas emissions, electromagnetic emissions, gap theory , seismic theory, abnormal animal behaviour ,etc to enables early warnings for earthquakes and tsunamis.

Note : possible collaborating with the optical, sub sea and seismic research communities to use all of our global cable infrastructure for greater societal benefits.