The tsunami-generated magnetic field is a magnetic field that show up
with the moving of tsunami. In the previous studies, researchers claimed
that the tsunami-generated magnetic field arrives earlier than the
tsunami sea level change based on analytical solutions and numerical
simulations. In this paper, we used the world's first simultaneous data
of sea level change and magnetic field in the 2009 Samoa and 2010 Chile
tsunamis to study the relation between these two physical quantities. We
found that the vertical component of tsunami magnetic field arrives
earlier than the sea level change. Moreover, the horizontal component of
tsunami magnetic field arrives even earlier than the vertical component.
The tsunami magnetic field was also revealed that it can be used to
estimate the tsunami wave height very accurately. We investigated the
observed tsunami magnetic field by our 3-D time-domain simulation.
However, the currently existing tsunami source models were unable to
reproduce the observation in our research area. We confirmed that a
better source model can improve the simulation. It follows that our high
precision tsunami wave height data converted from the magnetic field
should be used to construct a better tsunami source model.