  The vertical component (Z) of the geomagnetic field observed by ground-based
observatories of the INTERMAGNET network has been used to analyze the effects
of the movement of electrically conducting sea water through the geomagnetic
field due to a propagation of a tsumani. The purpose of this work is to study
the geomagnetic variations induced by the tsunamis occurred at 26 December,
2004, 27 February, 2010 and 11 March, 2011. For each case study, we selected
four magnetic stations belonging to the INTERMAGNET programme that were
influenced or more direct affected by the tsumani. To detect these disturbances
in the geomagnetic data, the discrete wavelet technique have been used in four
levels of decomposition. We were able to detect the localized behavior of the
geomagnetic variations induced by the movement of electrically conducting
sea-water through the geomagnetic field, i. e., the identification of
transients related to the tsunamis. As well, using the minutely magnetogram
data, it was able to localize the initial phase and time of the tsunami maximum
height. The first interpretation of the results suggests that discrete wavelet
transform can be used to characterize the tsumani effects on the geomagnetic
field, but need further study.
