Estimation of tsunami direction and horizontal velocity field from tsunami magnetic field

During tsunamis, the interaction between moving seawater and the Earth's magnetic field generates a magnetic field detectable by electromagnetic sensors located on land or on the seafloor. In this study, we introduce new methods for estimating tsunami propagation direction and horizontal velocity fields using tsunami magnetic field data. We derive a transfer function that establishes a relationship between the tsunami magnetic field and the velocity field, emphasizing the alignment between the horizontal magnetic field and the tsunami's propagation direction. This transfer function was validated with data from the 2009 Samoa and 2010 Chile tsunamis. Our findings show that tsunami horizontal velocities and directions can be accurately determined from these magnetic fields. This advancement enables the use of tsunami magnetic fields to provide comprehensive data for tsunami warning systems and to improve the inversion of tsunami seismic sources.This article is part of the theme issue 'Magnetometric remote sensing of Earth and planetary oceans'.