Geoscience Reference
In-Depth Information
and EQ
32
, events of relatively low energetic levels, are not marked. Several anomalies
in vertical component
E
z
of the quasi-static electric fi eld related to EQ
24
are listed in
Table 1. It is diffi cult to determine the infl uence of the event EQ
35
that is in vicinity
of EQ
24
.
Figure 6b.
Disturbances in
Ez
component of the quasi-static field, orbit 283.
The appearance of similar anomalies in vertical component
E
z
of the quasi-static
electric fi eld could be provoked by EQ
24
, EQ
35
, and EQ
65
in the South Pacifi c and
Southern Iran (see Table 1).
CONCLUSIONS
Quasi-static electric fields anomalies in the upper ionosphere associated with seis-
mic activity during August-September 1981 are investigated by using the observation
data of the INTERCOSMOS-BULGARIA-1300 satellite in conditions of magneti-
cally very quiet, quiet, and medium quiet days. The observations suggest the presence
of quasi-static electric field disturbances related to seismic activity above earthquake
sources in the Southern and the Northern Hemispheres at different latitudes. The dates
of seismic events, their origin time, locations of epicenter, magnitude, and depth in the
observed period are obtained from USGS website.
The analyzed period is short and includes 38 days. New specialized software has
been used for processing of ionospheric disturbance zones on the background of the
trend for all orbits' tracing and of data for the represented plates of the Earth. The
obtained results about 73 events selected from INTERCOSMOS-BULGARIA-1300
data-base are summarized in the Table 2. We exclude the possible effects from two
foreshocks to 14 aftershocks. Twenty six orbits for observation of 92 main shocks are
used. No disturbances from 35 events are observed. In the chapter 52 positive pre- and
post-possible effects are shown as:
• 25 pre-effects of nighttime and two pre-effects of daytime observations;
• 21 post-effects of nighttime and four post-effects of daytime observations; and
