Electromagnetic Effects Resulted from Natural Disasters - Ultra and Extremely Low Frequency Electromagnetic Fields - page 394

of magnetometers from those measured by a reference magnetometer. The data
processing is based on theoretical formulas describing the quasi-steady field of
the magnetic dipole or of the current element. More precisely, these formulas give
an evaluation of the partial derivatives of the magnetic perturbations. In principle,
this procedure allows us to extract all the dipole parameters including its depth
orientations and so on, as was illustrated by the example of magnetic dipole.
This promising technique has not been used yet in practice possibly because of
complicated mathematical supplements.
The problem of direction finding for a ULF source is still far from completion,
although this information can be extremely useful for the interpretation of experi-
mental data and for understanding the origin of the ULF signals and, in particular,
for finding the electromagnetic signals possibly related to an impending EQ.

10.1.8 Other Electromagnetic Phenomena Possibly

Associated with EQs

A special credit has been paid in the last decade to monitoring of the seismo-active
regions from space in visible and infrared (IR) ranges (e.g., Gorny et al. 1988 ; Qiang
et al. 1991 , 1999 ; Salman et al. 1992 ; Tronin 1996 , 1999 , 2002 ; Tronin et al. 2002 ;
Liu et al. 2000 ; Tramutoli et al. 2001 ; Ouzounov and Freund 2004 ). The analysis of
the outgoing IR radiation detected over sparsely populated territories at nighttime
conditions has shown the presence of anomalies of the outgoing Earth's radiation
flux associated with large structures and fault systems of the Earth's crust. The
nighttime conditions are the most favorable for the IR monitoring of the ground-
surface temperature since there are no solar heating. The minimal absorption of IR
by the atmosphere corresponds to wavelength intervals 3-5 m and 8-13 m. The
second interval termed as a second transparency window is preferable to the first
one because the outgoing radiation peak which corresponds to the ground surface
temperature 273-373 K lies within 7.7-10.5 m.
Because of high spatial (0.5-1 km) and temperature (0.1-0.5 K) resolutions this
method has been used for the analyses of lineaments, morphological structures,
and tectonic movements. The data processing of NOAA-series satellite survey has
shown an increase in the average ground temperature of several Kelvin at the foot
of Kopetdag in Central Asia (Tronin 2002 ; Tronin et al. 2002 ). The anomaly area
was 25-30 km wide and about 500 km in length. Another type of anomaly of about
50 km wide and 300 km long was found at the foot of the Karatau Range that roughly
coincides spatially with the Karatau fault. This procedure promotes the elimination
of average seasonal temperature trend, the reduction of the climatological and other
effects (Tramutoli et al. 2001 ). The capability of the refined noise-removal approach
has been demonstrated for the case of the Irpina-Basilicata EQ of November 23,
1980 (M s D 6:9).