Fractal characteristics of the ULF emissions along a meridian profile, based on the 210 MM stations data

Abstract

Fractal analysis of magnetic records (1 Hz sampling rate) of 5 stations (Guam, Moshiri, Paratunka, Magadan, and Chokurdakh) located along the 210 magnetic meridian (210 MM) has been performed using the Higuchi method. The period of 22 months (October 1992 to July 1994) that embodies the date of the strong Guam earthquake of 8 August1993 has been considered. A comparison of the ULF emissions scaling parameters (spectral exponents β and fractal dimensions D) obtained at different latitudes has been made. Dependence of β and D on the Kp index of geomagnetic activity has been analyzed for each of the 24 local time intervals. It is revealed that D decreases ( β increases) with increasing geomagnetic activity at all stations, but the rates of decrease (increase) are different at different stations and in different time intervals. It is shown that the evening, night and early morning hours are preferable to study magnetospheric effects, whereas the noon hours are the most suitable for the analysis of lithospheric effects. A possibility of using the data of the 210 MM stations as reference materials for the Guam seismically active area is discussed.