The two sets of figures show some corroborative features, notably the low frequency from 1860 to 1870.
It is also necessary to notice that shunt instruments cannot be used for high frequencies, as then the relative inductance of the shunt and wire becomes important and affects the ratio in which the current is divided, whereas for low frequency currents the inductance is unimportant.
We have gathered a data file of about 200 low frequency volcanic earthquakes at Torfajökull during the years 1996 to 2001.
It is clear that seismic parameters, including the intermittency are very important in investigating the source of the low-frequency earthquakes.
The family of electromagnetic waves from the high-frequency gamma rays to the relatively low-frequency radio waves forms what is called the electromagnetic spectrum.
