Tsunamis can now be detected ahead of time by their magnetic fields

A new study published in the Journal of Geophysical Research: Solid Earth has found a way to use tsunamis' magnetic fields to detect them sooner.

Magnetic fields are generated as tsunamis move conductive seawater throughout the Earth's magnetic field. Researchers had already predicted that detectable changes in the magnetic field would arrive before a change in sea level but had yet to measure simultaneous data on both parameters to observe the phenomenon.

The new study uses data from two tsunamis, one in 2009 in Samoa and one in 2010 in Chile, which have data relating to their magnetic fields and seafloor pressure. The research shows the magnitude of the magnetic field can be used to estimate the height of the tsunami wave.

The magnetic field arrives before a detectable change in sea level, but this depends on the depth of the water. Over depths of 4,800 meters, the field arrived one minute before a sea-level change. Scientists can detect changes in wave height of only a few centimeters, thanks to the sensitivity of the magnetic field.

"It is very exciting because in previous studies we didn't have the observation [of] sea-level change. We have observations [of] sea-level change, and we find that the observation agrees with our magnetic data as well as theoretical simulation," said Zhiheng Lin, a geophysicist at Kyoto University and the senior study author.

You can read more from the study here.