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about ionospheric precursors of earthquakes (Sorokin and Chmyrev, 2002; Sorokin et
al., 2001a). This model provides an explanation of some electromagnetic and plasma
phenomena connected to the effects of amplifi cation of the DC electric fi eld in the
ionosphere. A theoretical model of the electric fi eld disturbances caused by the con-
ductivity currents in the atmosphere and the ionosphere initiated by external electric
current was proposed by Sorokin and Yaschenko (2000) and Sorokin et al. (2001b).
According to this model, the external current arises as a result of emanation of charged
aerosols transported into the atmosphere by soil gases and the subsequent processes
of upward transfer, gravitational sedimentation and charge relaxation. Further devel-
opment of this model includes a new method for computation of the electric fi eld
in the atmosphere and the ionosphere over active faults for arbitrary spatial distri-
bution of external current in oblique magnetic fi eld (Sorokin et al., 2005, 2006). In
our previous chapters (Gousheva et al., 2005a, b; 2006a, b, 2007, 2008a, b) on the
basis of INTERCOSMOS-BULGARIA-1300 satellite data we found arguments for
seismically-induced increases in the vertical components of the quasi-static electric
fi eld up to 2-10-15 mV/m in the near equatorial, low, middle, and high latitude iono-
sphere. In this chapter we present supplementary data about quasi-static electric fi eld
anomalies according INTERCOSMOS-BULGARIA-1300 satellite information over
the Southern Atlantic Ocean, Tonga-New Hebrides region, Northern Islands of New
Zealand, Indonesian region, Eastern Canada, Labrador Sea, Caribbean region, Central
America, Western coast of South America, South-West Pacifi c Ocean, Kuril Islands,
Aleutian Islands, Southern Pacifi c Ocean, Southern Iran during seismic events in
August-September 1981.
SATELLITE AND SEISMIC DATA SELECTION
The INTERCOSMOS-BULGARIA-1300 satellite is launched on August 7, 1981. It
has a perigee of 825 km, an apogee of 906 km and an orbital inclination of 81.2
°
.
The INTERCOSMOS-BULGARIA-1300 satellite operates during 2½ years. The reg-
istrations of the quasi-static electric field are carried out by the IESP-1 instrument.
The IESP-1 instrument measures the electric field using the Langmuir double probe
floating potential method, identical with a voltmeter. There is a potential difference
between two top-hat probes (Pedersen et al., 1984, 1998). Two sensors are applied to
obtain the values of the both horizontal and one vertical component. The basis for the
X and Y components is 7.5 m and for the Z component--1.8 m. The dynamical range
is ±300 mV/m for the X component, ±600 mV/m-for the Y one and ±90 mV/m-for
the Z one. The sensitivity is 1 mV/m for each component. The
Ex
is the horizontal
component almost parallel to the magnetic field line;
Ey
is the horizontal component
perpendicular to the magnetic field line;
Ez
is the vertical component to the Earth sur-
face. It is a difficult task to study the relations between the quasi-static electric field
data and the seismic activity because the passes of satellite over the epicenter zones
were rarely. The first task is to select the satellite data about ionospheric anomalies re-
corded over seismic zones with information for earthquakes in the time period August
14-September 20, 1981. Twenty six orbits are chosen above sources of 73 earthquakes
complying with the following conditions:
