Geoscience Reference
In-Depth Information
Fig. 3.42
Monitoring of the TM-71 in Golyamata Tsepnatina Cave
3.3.2
Studies in Rhodopes Mountains
prognostic intensity is I = 9 MSC-64. During the last
century, two strong seismic events occurred there—the
Velingrad earthquakes in 1905 (M = 4.2) and 1977
(M = 5.3) (Fig.
3.44
).
From a morphological point of view, the Lepenitsa
Cave is a good example of a multiphase cave system
that consists of three different stages—active level
(''The water gallery'') and two fossil upper levels.
The height difference between the levels does not
exceed 30 m. The total length of the cave passages is
1,525 m. The plan of the cave was made in the period
1970-1972 by the speleologist Petar Tranteev with
the help of Konstantin Spasov, Martin Tranteev, and
Boyan Tranteev. The main gallery has a length of
about 800 m (Fig.
3.45
).
The cave deposits are fluvial, detritic, and numer-
ous speleothems: stalactites and stalagmites of dif-
ferent types, columns, draperies, gurs, etc. The wide
occurrence of fractured, broken, and inclines speleo-
thems with possible coseismic origin was reported by
Shanov et al. (
1998
), Kostov (
2000
,
2008
).
The prevalence of cracked, broken, or inclined
speleothems with possible coseismic origin was first
reported by Shanov et al. (
1998
), (
2001
), and Kostov
(
2000
). During several field studies conducted in the
period 1998-2005, in the cave are identified the fol-
lowing indicators of seismotectonic effects on cave
sediments:
The Rhodopes Mountains stretch between Bulgaria
and Greece. The karst in the Bulgarian part of the
massif (Rila-Rhodopean karst zone, to which also
belong Pirin and Slaviyanka mountains) is present
almost everywhere and occupies 1,966 km
2
.Itis
formed mainly of Proterozoic marbles from the
Dobrostan Marble Formation. More than 600 caves
have been surveyed in Rhodopes till now and the
longest is Yagodina Cave—8,501 m. The deepest pot-
holes are Banski Suhodol 9/11 Cave in Pirin Mountain
(more than 300 m according to the results from the
Summer Caving Expedition ''Banski Suhodol 2013'')
and Drangaleshka Dupka Cave with depth of 255 m.
3.3.2.1 Lepenitsa Cave
The Lepenitsa Cave is a spring cave situated in the
northern part of the Batak Mountain which forms a
part of the Western Rhodopes Mts. The small
entrance is located on the left bank of Chuckura
River, nearly 13 km south of the town of Velingrad. It
is formed of highly fractured Proterozoic marbles of
the Dobrostan formation (Fig.
3.43
).
The cave is located in one of the seismically strongest
active regions in Bulgaria. The maximum observed
shakeability in terms of intensity is determined as I = 7
MSC-64 and for a period of 10,000 years, the maximum
