Google Earthquake Detection system: Here all you need to know how it works ?

Google bets on submarine optic fibers to track earthquake, tsunami faster

Earthquakes:

An earthquake is a shaking of trembling of the earth's surface, caused by the sudden movement of a part of the earth's crust. They result from the sudden release of energy in the earth's crust that creates seismic waves or earthquake waves. There are annually 8000-10000 earthquakes in the world, which come to about an earthquake every hour. Actually, there are many more undetected, because there are no stations to record them over the oceans covering a very large surface of our earth.

How Earthquake Happens ?

Earthquake facts:

Scientists used the Richter Scale for many years to measure earthquakes but now largely follow the "Moment Magnitude Scale", which USGS says is a more accurate measure of size. Measures the size of earthquakes in terms of the energy released, using the "seismic moment". It measures force needed to generate a seismic movement.

Moment Magnitude (Mw), also called Moment Magnitude Scale, quantitative measure of an earthquake's magnitude (or relative size), developed in the 1979 by Japanese seismologist Hiroo Kanamori and American seismologist Thomas C. Hanks.  

The biggest problem with earthquake:

There is proper warning system for Earthquakes. We only get vague warning like "an Earthquake can occur in this area in the next 100 years or so".

A recent report:

The last big tremor in the Himalayas was the Nepal earthquake of 2015 with a moment magnitude (Mw) of 7.8, killing nearly 9000 people and injuring 22000. The quake flattened large parts of the capital Kathmandu.

The quake was strong enough to shift Kathmandu south by 1.5 m, wasn't a big earthquake like the ones that measure over Mw8. It did, however, set the ground conditions that make a far larger earthquake, a "big one",more favorable. 

Is it possible to detect earthquakes with submarine cables? We think it might be.https://t.co/6oIZTxg1wk

— Sundar Pichai (@sundarpichai) July 16, 2020

Google's next big project:

Google recently conducted an experiment to detect undersea earthquakes and tsunamis with the help of sub sea fiber optic cables. Google Earthquake Detection System technique works across tens of thousands of kilometres where data travels as pulses of light at over two lakh kilometres per second.

Fiber optic cables will detect disturbances on the seafloor. These cables carry data and the internet across continents. During transmission, light's SOP changes when it encounters disturbance along the cable. Seismic activity can be recognized by tracking these disturbances. 

Sub Sea Fiber Optic Cables

Valey Kamalov and Mattia Cantono from Google Global Networking posted a blog detailing how Google plans to detect earthquakes. "Last October, an idea came to us: we could detect earthquakes based on spectral signature-performing a spectral analysis of Stokes parameters to look at frequencies that are typical of earthquakes", they said in the blog post. In this article we give you details about Google Earthquake Detection System like how its work and how its developed by Google.

How does the Google Earthquake Detection System technique work ?

The sub sea  fiber optic cables carry data as pulses of light traveling at t a rate of 204,190 kilometres per second. The pulsing light encounters distortions as it travels thousands of kilometres across the cable. At the receiving end, the light pulses are observed, and the deformations are rectified by digital signal processing. With the help of SOP (State of Polarization), Due to mechanical disturbances along the cable. seismic activity is detected. Its technique is said to complement the existing array of dedicated seismic sensors, and not replace them.

In the year 2019, the researchers at Google started monitoring the state of polarization (SOP) on global submarine cables. Initially, it was observed that the SOP was fixed, even after the signal passes over 10,500 km. For a few weeks, the SOP revealed no changes indicating any seismic event. 

Google's SOP spectrograms on submarine cables indicating any seismic event

On January 28, 2020, a magnitude 7.7 earthquake was noted off Jamaica. This activity was recorded 1500 km far from the closest point of the cables at Google. After this event, many other common earthquakes were detected. On March 22, 2020, an earthquake of magnitude 6.1 was recorded on the East Pacific Rise. This time the event happened at a distance of 2000 km away from the grounds cable. A clear SOP activity was noted. 

On March 28, 2020, an earthquake of 4.5 magnitudes was recorded 30 km away from the pending cable. This generated a short spike in the SOP activity. Google said that this technique is just a demonstration as of now and much work needs to be done to understand the seismic data generated by the SOP as it changes drastically. The data is observed based on magnitude, location, etc. and is different for different seismic activity.