A new study shows that the magnetic field caused by a tsunami arrives before the sea level changes, and that its size can be used to figure out how high the tsunami’s waves will be. In their study, the authors found that the magnetic field arrived about one minute before the sea level changed over a 4,800-meter deep sea. If this information was used in tsunami risk models, it could give people an early warning of a disaster that could save lives.
Magnetic field created by a tsunami is the warning sign
Sea level changes during two tsunamis were studied by the research team. They looked at how the sea level rose at the same time as changes in pressure on the seafloor and magnetic fields. They found that the arrival of the magnetic field, like the start of a seismic wave, can be used to predict tsunamis before they reach the coast. The magnetic field created by a tsunami is so strong that even a wave height of a few centimeters can be picked up.
A study that compared the magnetic field data with changes in sea level from changes in pressure has been needed for a long time. The researchers are some of the first to really compare how well magnetic field data and pressure data match up. Both horizontal and vertical components of the magnetic field can accurately predict changes in sea level if models include accurate information about the depth of the ocean and the electrical structure below the seafloor. These types of data from tsunamis aren’t always available because it’s hard to keep up with the few observational stations that already exist. Another thing to note is that these findings only apply to deep-sea environments, not coastal ones, where the deep water helps to filter out environmental noise so that the sound of a tsunami can be heard.
