Earthquake; A catastrophe of nature. There are an average of ten earthquakes of different magnitude on the earth every hour. Tech giant Google is working on this earthquake. Google CEO Sundar Pichai said that Google is planning to build an earthquake forecasting system as their next big project.
What is Google saying? Google recently tested using fiber optic cable, this technology can provide earthquake and tsunami warnings around the world. There is a long history of using optical fiber for alert, forecasting or sensing applications. However, most of these strategies are effective at distances up to a maximum of 100 km. Google says it is moving toward a technology that operates over distances of more than a few thousand kilometers, and that it is possible to use ordinary fiber under the sea instead of specially sensitive fibers and equipment. Hopefully, Google's technology will be able to use common tools that are found in a large number of fiber optic systems in the world.
Why fiber optic cable? Fiber optic cables connect distant continents with the ocean floor, and most of the international traffic on the Internet is done with these cables. Google also has its own submarine cable. At the moment their 15 fiber systems are spread over a total distance of 112 thousand kilometers. Cables are being used to connect, search, transmit and receive information around the world at the speed of light by connecting to global networks. These cables are made using optical fiber, which transports information by traveling 2 lakh 4 thousand 109 kilometers per second.
Crossing such a huge path often leads to distortion of information. This is why there is a digital signal processing system at the receiving end by which data distortions are corrected. One of the characteristics of light identified as part of optical transmission is the state of polarization (SOP). This is the situation that is showing hope in the plan to get an earthquake forecast. This condition can change in response to mechanical disturbances, including cables, and enable us to detect seismic activity by detecting these disturbances.
First attempt seven years ago: In 2013, Google began working on its first earthquake forecasting system. At that time, instead of optical fiber under the sea, they conducted this test on land-based cables. They focused on how to use SOP data to better understand deviations from ground-based wire detection, but Google did not do so at the time, as environmental issues in the area were too much of a hindrance to seismic signal detection.
Light of hope in scientific article: In 2018, a team of 12 scientists from the United Kingdom, Italy and Malta published a research report. The article mentions the initial success of detecting earthquakes by observing progressive changes through both land and sea using a short band ultrasound laser.
The team limited their experiments to a depth of less than 535 kilometers on land, 96 kilometers under sea and 200 meters in shallow water. In a recent blog post published in Google Cloud, Google authorities said that this article made scientists interested in working on this issue anew. In this context, they started thinking about how to detect earthquake data using fiber optic cable under the sea floor. In October of last year (2019) they came up with an idea to talk about the possibility of identifying earthquakes based on spectral reflections. It is possible to get the expected results in the spectral analysis of Stokes' parameters to see the frequencies characteristic of earthquakes.
Success: Towards the end of 2019, Google began monitoring the SOP data of several of their submarine cables spread worldwide. The SOP was remarkably stable in the early stages of this observation, even after the signal was found to be stable after crossing about ten and a half thousand kilometers. For the next few weeks, the sea floor was probably very calm, at this time no SOP showed any signs of an earthquake.
January 22, 2020; Google claims to have detected a submarine cable 1500 kilometers from the epicenter of a magnitude 7.7 earthquake in Jamaica that day. A plot of SOP shows a clear spike about five minutes after the earthquake, which is related to the duration of the earthquake wave travel from Jamaica to Cable, and the spike lasted about 10 minutes.
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