Earthquake Detection System by Google could be a revolutionary life-saving approach that is capable to save millions of lives every year. Tech giant Google has discovered a new approach to test  it’s earthquake and tsunami warning system with the undersea fiber optic cables to sense disturbances on the seafloor.Let’s learn in details.

Earthquake Detection System by Google

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Let’s start from the basic concepts.

What Is Earthquake?

Earthquake is the shaking of earth’s crust caused by displacement in tectonic plates or volcanic eruption. Plate displacement or volcanic eruption on the uppermost layer of the earth releases sudden energy caused by elastic strain, chemical reaction or motion of massive body that generates a series of seismic waves. These waves travel through the crust and the upper mantle and also rumble earth’s surface.

Facts
There are around 20,000 earthquakes being happened around the world annually in average.

What Is Seismic Waves?

Whenever there is a tectonic plate displacement or volcanic eruption being occurred, energy releases. Seismic waves are the waves of this released energy transmit through the surface of the Earth. There are three types of waves. Richard Dixon Oldham was the first to separate P waves, S waves and L waves

Primary Waves (P Waves) 

  • Short waves with high frequency longitudinal waves. So, it can travel through solid, liquid and gas.
  • P waves are not detected between 104° and 140° as they get refracted by the liquid outer core.

Secondary Waves (S Waves)

  • Short waves are high frequency waves
  • Traverse waves. So, it can go through only solid.
  • S waves are not detected beyond 104° as the waves cannot pass through the liquid outer core of Earth.

Surface Waves or Long Waves (L Waves)

  • Long waves
  • Damages Earth’s structure

Seismic Waves

Know Some Terminologies

  • Hypocentre– Hypocentre is commonly termed the focus. This is the point where seismic waves get generated. It is hidden under the ground. Seismograph can detect it.
  • Epicentre – It is the point on the Earth’s surface closest to the Focus.
  • Shadow Zone – It is the area between 104° and 140° from the epicentre. Here, seismic waves cannot be detected as P waves get refracted and S waves cannot pass through Earth’s liquid outer core. 
Seismograph

Seismograph

It is a scale which indicates the strength of energy released. There are several scales

  • Mercalli Scale was discovered by Michele Stefano de Rossi and Franƈois-Alphonse Forel in 1878. It is a 10-point scale prepared focusing on the intensity of earthquake.
  • Modified Mercalli Scale was discovered by Harry O. Wood and Frank Neumann in 1931. It was the Upgradation of Mercalli Scale from 10 points to 12 points indication.
  • Richter Magnitude scale was discovered by Charles Francis Richter in 1935. It measures earthquake on basis of its magnitude; not intensity.
  • Moment Magnitude Scale was discovered by Thomas C. Hanks and Hiroo Kanamori in 1979. This latest technology is almost accurate. It measures the force that pulses seismic waves.

Significance of Earthquake Detection System by Google

Technology can save us from deadliest natural disasters like Typhoon or Cyclones, but we can’t save us from Nature’s wrath in the form of earthquakes.

Look at some deadliest earthquakes in the decade

  • Haiti experienced earthquake of magnitude 7.0 in January 12, 2010 and 316000 people were killed.
  • Sumatra, Indonesia experienced tsunami of magnitude of 9.1 in December 26, 2004 and 227898 people were killed.
  • In December 16, 1920, Halyuan province of China encountered an earthquake and 200000 people were reported killed.
  • Japan reported 143000 peopled killed at a earthquake of magnitude of 7.9 in September 1, 1923.
  • 110000 people were killed in an earthquake in Ashgabat. Turkmenistan in October 5, 1948.
  • Peru faced an earthquake where 66.000 people were killed in 1970.
  • Bhuj,Gujarat in India in 2001 and Kathmandu,Nepal in 2015 are the two most recent earthquakes in Indian continent where many people were reported killed.
Earthquake Zones

Earthquake Zones

Recently scientists have cautioned us on a potential quake in the Himalayan region of large magnitude. 

Pacific Ring of Fire remains under continuous threat a series of quakes in all over the year. The Ring of Fire is the Pacific region which is the home of over 450 active volcanoes, including world’s most active volcanoes like Mount St. Helens in the USA, Mount Fuji in Japan and Mount Pinatubo of Philippines. Pacific Ring of Fire is also known as the Circum-Pacific belt.

Pacific Ring of Fire

Pacific Ring of Fire

Facts
Around 90% of the world’s earthquakes occur in the Ring of Fire, and 80% of the world’s largest earthquakes.

Above mentioned data and facts clearly indicates that we are floating over moving plates and we don’t have any idea on what’s going on under the earth’s crust. There could be a massive quake in anywhere,anytime. But we are clueless. So there is a desperate need of an accurate and efficient earthquake warning system as there are no accurate earthquake forecasting system still now. We can forecast about almost all terrestrial calamities except earthquake and tsunami. And thanks to Google which has pioneered to safeguard human race through it’s new innovation.

Google is planning to use existing fiber optic network over the seafloor. Fiber optic cables allows data transfer as pulses of light at over two lakh kilometres per second.

Here is a map of network of submarine cables or the fiber optic network over the seafloor

Submarine Cable Map

Submarine Cable Map

Image Source

In 2013, Researchers from Google were working on how SOP (state of polarization) data could be utilized. With this phenomenon and some mechanical disturbances, a mild seismic wave got trapped in the system.

What is State of Polarization (SOP) in Optical transmission?
The optical fiber transmission network experience some polarization effects. Optical Fiber Cables work on the principal of total internal reflection of electromagnetic wave. As it allows data transmission or propagation under the principal of Maxwell equations. The electromagnetic waves are featured by two polarization components i.e. along the x and y axis. The polarized light wave propagates in z direction. This polarized electromagnetic wave can be derived from two linear polarized components along x and y axis.


In 2018, Google announced about detection of seismic waves on subsea as well as terrestrial links. They started monitoring from 2019.

Google was able to detect some pulses of seismic waves near Jamaica on 28th January of 2020. The pulses were recorded at 7.7 in magnitude. After that, they confirmed about building this system after being convinced about the system’s efficiency and accuracy.

Google’s earthquake detection approach involves detailed study of several variables such as magnitude, location etc. When an earthquake epicentre is produced within the sensing zone of a Subsea Fiber Optic cable, the earthquake warning system transmits data at the speed of light which could be used as warning for potentially affected communities in milliseconds.

What is Subsea Fiber Optic Cables?

Subsea Fiber Optic cable is used as submarine communications cable. These cables are laid on the seafloor between the land-based stations. Such subsea fiber optic cables connect two or more land based stations from different or same continents. Subsea Fiber Optic cables carry telecommunication signals across oceans and sea.

Optical Fiber Cables on Seafloor

Optical Fiber Cables on Seafloor

There is no doubt that Google is going to develop revolutionary earthquake detecting system. However, this system needs further research on advanced mathematics, algorithms and data analytics with the help of cloud technology to get most accurate and efficient data.

Evolution of Earthquake Prediction Methods

Animal Behavior

In old days there were no technology that was able to predict earthquakes. It was found that some unusual animal behavior was noticed before an earthquake in Greece in 373 BC. However, in recent days scientists have researched and found that Rats, weasels, snakes, ants, centipedes, fishes, toads, birds reportedly start showing abnormality in their routine behavior and leave their natural habitat and moves away before an earthquake.

Radon emissions

Radon is a natural radioactive element found almost everywhere on the earth. Radon is found in soil, groundwater and as well as in the lower atmospheric region. Research have indicated that isotopically trapped Radon gas is generated during rock collision or tectonic movements. However, Radon diffusion is not an established method as it shows true from false anomalies in different seismic zones. Radon anomalies were studied to correlate with some micro earthquakes recorded during 1989 to 1999 in North-West Himalayan region.The analysis revealed that the accuracy of radon anomalies was found to be 62 % for the seismic zone.  However, it can be concluded that more comprehensive research and analysis is needed to establish the exact co-relation between the Radon emissions and earthquake.

Thermal remote sensing approach

Seismologists presented a theory on how land surface temperature (LST) is increased during the tectonic movements. Research and analysis also revealed that a transient thermal rise in land surface temperature (LST) is observed around epicentral areas of earthquakes. The temperature rise could vary from 2 to 12° C. Satellite thermal remote sensing technology in detecting rise of land surface temperature (LST) could be another milestone if implemented with proper infrastructure and further research.

 

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