Fluctuations in the magnetic field will warn of the approaching tsunami

(ORDO NEWS) — Changes in the magnetic field can be registered a little earlier than changes in sea level, saving valuable time from the coming wave.

With the threat of a tsunami, every minute of delay can become a matter of life and death. Scientists are using a variety of tools to predict when waves are approaching and take action to protect coastal communities and their inhabitants.

They track the acoustic and seismic vibrations of tsunami-generating undersea earthquakes, and magnetic field monitoring may be added to this arsenal in the future. This possibility is indicated by the authors of an article published in JGR Solid Earth . The work is also described in a press release from the American Geophysical Society (AGU).

Salty seawater conducts electricity, and the movement of large masses of water during a tsunami can cause small, localized changes in the magnetic field. This was not a secret for scientists before, but they did not have reliable data confirming such a connection.

Therefore, Zhiheng Lin and colleagues at Kyoto University analyzed magnetic field monitoring data collected during the 2009 tsunami in Samoa and 2010 in Chile. The authors of the study compared information about fluctuations in the magnetic field and the water level (which is recorded by pressure sensors at the bottom).

The work showed that changes in the magnetic field precede changes in water level caused by the movement of a tsunami. How early they appear depends on the depth of water in a particular area of ​​the ocean, but scientists noted that at this value of 4800 meters, the magnetic field “overtook” the tsunami by about a minute. Moreover, the intensity of the field oscillations correlates with the wave height, making it possible to predict it with accuracy.

“They did what should have been done long ago,” commented US geophysicist Neesha Schnepf on the publication. The authors are confident that new tools will soon be deployed at sea to track the tsunami threat. However, they notice that this method can only be applied in the open sea, away from the inhabited coast, where large volumes of water make it easier to filter out extraneous signals and noise.

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