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Fig. 3.41
Map, cross sections, and longitudinal profile of Golyamata Tsepnatina Cave
detailed survey was made in 1985 by Shumen cavers A.
Spasov and M. Mirchev (''Madarski Konnik'' Caving
Club). Description of the cave was made in Mircheva
et al. ( 2004 ). The cave has no special protection status
but is situated within the boundaries of the National
Historic-Archaeological Reserve ''Madara''.
As mentioned above, an extensometer TM-71 was
installed in the cave in April 1990, which was a part
of the monitoring system for study of the recent
microdisplacements around the monument together
with other two gauges TM-71 near the Madara
Horseman bas-relief and a few pin marks. The data
from the instruments are monitored by the Geological
Institute of Bulgarian Academy of Sciences several
times during the year (Fig. 3.42 ).
Until 1994, these movements were characterized
by a pronounced sinusoidal curve showing the trend
and
(Dobrev and Avramova-Tacheva 1997 ). The moni-
toring data from the last 10 years are discussed in a
special publication in preparation.
The response of the TM-71 instrument to the cata-
strophic earthquake in Izmit, Turkey on August 17,
1999 (M = 7.4) is interesting. The epicenter was
located 370 km S-SE from Madara Plateau. This
earthquake was felt in many parts of Bulgaria, includ-
ing the nearest towns of Shumen and Varna. Immedi-
ately after the earthquake measurement was carried out.
It was found that the extensometer been damaged due to
strong fluctuation motion (shaking) of the two slices.
After reconstruction of the gauge, we made accurate
reconstruction of the movement taking place during
this earthquake. It was found that: DX = +6.91 mm
shortening of the fissure; DY = +46.78 mm horizontal
slip to S-SE; DZ =+10.43 mm vertical movement
(uprising) of the rock slice.
some
sharp
movements
with
various
origin
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