Tsunami waves generate a magnetic field as they move conductive seawater through the Earth’s magnetic field. The researchers predict the tsunami’s magnetic field will arrive before sea level changes, making it useful for early warning.
“This is very interesting because we found that the observations of sea level changes are in accordance with the magnetic data and theoretical simulations,” said Zhiheng Lin, a geophysicist at Kyoto University, quoted by SINDOnews from the phys.org page, Wednesday (22/21/2021).
This new study provides concrete evidence for predicting tsunami wave heights using a tsunami’s magnetic field. This study uses data from the 2009 tsunami in Samoa and the 2010 tsunami in Chile. (Read also; This is the difference between a car being a tsunami victim and a flood victim )
The research is published in the AGU Geophysical Research Journal: Solid Earth, which focuses on the physics and chemistry of the solid Earth. The study confirmed that the magnetic field generated by the tsunami arrived before sea level changes. The magnitude of the magnetic field can be used to estimate the tsunami wave height.
How early the magnetic field arrives depends on the depth of the water, but the study found an initial arrival time of about one minute, before sea level changes in oceans as deep as 4,800 meters. This information can provide disaster early warning if incorporated into a tsunami risk model and thus save many lives.
The research team looked at simultaneous measurements of sea level change from data on seafloor pressure and magnetic fields for the two tsunamis. They found that the main arrival of the magnetic field, similar to the beginning of seismic waves. This can be used for early warning, because the magnetic field generated by a tsunami is so sensitive that even a wave height of a few centimeters can be detected.
“They did something that basically needed to be done. We needed a study to compare the magnetic field data to changes in sea level. So it must be very useful,” said Neesha Schnepf, a geomagnetic researcher at the University of Colorado. (Read also; BMKG Explains 8 Meter Tsunami Potential in Cilegon Only Worst Scenario Mitigation )
When the researchers compared the horizontal and vertical components of the tsunami’s magnetic field with changes in sea level, they found that both components could accurately predict sea level changes. This includes good data on the depth of the ocean and the electrical structures beneath the seafloor.
“I think the practical goal is to improve predictability, both about which areas might need to be warned and how badly the tsunami will hit certain places,” said Schnepf.
(Web)
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