What is Google Earthquake Detection System?
Tech giant Google has developed a new way to detect undersea earthquakes and tsunamis with the help of subsea fiber optic cables. While this system of detection already exists, the company claims that their technique works over tens of thousands of kilometres in comparison to the existing techniques that are effective over distances up to 100 km. The company also stated that the previous systems require special sensing fiber and special equipment while the technique used by the company to detect disturbances on the seafloor is based on the existing fiber.
It is known that fiber optic cables connect different continents along the seafloor and much of international traffic travels over these cables. These cables are used by Google to share, search, send, and receive information around the world at the speed of light.
Is it possible to detect earthquakes with submarine cables? We think it might be.https://t.co/6oIZTxg1wk— Sundar Pichai (@sundarpichai) July 16, 2020
How does this technique work?
The subsea fiber optic cables carry data as pulses of light travelling at 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 detected, and the distortions are corrected by digital signal processing. With the help of SOP (State of Polarization), seismic activity is detected due to the mechanical disturbances along the cable.
What is meant by subsea fiber optic cables?
A subsea fiber optic cable is a submarine communications cable that is laid on the sea bed between the land-based stations to carry telecommunication signals across oceans and sea.
How does Google see this technique?
As per the company, today's era is dependent on technology that is spread on today's fiber optic networks. For this purpose, hundreds of thousands of fibre optic network is stretched around the globe and is operated by the governments, telecommunication providers and companies like Google. Thus, a collaboration with the subsea cable community will help the world in detecting and researching the seismic activity around the globe.
History of the technique
The company in a blog post stated that in the year 2013, the researchers were working on how SOP data could be utilized to get a better understanding of the deviations detected on a land-based terrestrial cable, but the project was dropped as the surrounding factors caused too much disruption to detect seismic signatures.
In the year 2018, a scientific journal was published on detecting earthquakes on both terrestrial and subsea links. This was based on the narrowband ultrastable laser that changes its phase. However, the links used were short and in shallow waters, which limits the practicality of the scientific study.
In the year 2019, the researchers at Google began monitoring SOP on global submarine cables. Initially, it was observed that the SOP was stable, even after the signal traversed 10,500 km. For a few weeks, the SOP intimated no changes indicating any seismic event. On January 28, 2020, a magnitude 7.7 earthquake was recorded off of Jamaica. This activity was recorded 1500 km away from the closest point of the cables at Google.
After this incident, many other moderate earthquakes were detected. On March 22, 2020, an earthquake of magnitude 6.1 was recorded on the East Pacific Rise. This time the event took place at a distance of 2000 km away from the company's cable. A clear SOP activity was recorded. On March 28, 2020, an earthquake of 4.5 magnitudes was recorded 30 km away from the company's cable. This created a short spike in the SOP activity.
The company also states 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 dramatically. The data is based on magnitude, location, etc. and is different for different seismic activity.
Thus, to create a strong earthquake detecting system, advanced mathematics and data analytics will be used by the researchers, where Google Cloud could prove to be of great help.