Direct measurement of present-day tectonic movement and associated radon flux in Postojna Cave, Slovenia

Šebela, Stanka; Vaupotič, Janja; Košťák, B.; Štemberk, Josef

doi:10.4311/jcks2009es0077

Cited by 35 publications

(19 citation statements)

References 24 publications

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“…Postojna Cave has been under permanent radon survey since 1995, because of elevated radon concentrations (Kobal et al ., ; Vaupotič et al ., ; Vaupotič, ). More recently, air temperature and pressure monitoring has been conducted to better understand radon emanations connected with microtectonic displacements of two monitoring sites (Gosar et al ., ; Šebela et al ., ; Šebela and Turk, ). All these studies have brought to light the complexity of the Postojna Cave microclimate, influenced by numerous known and unknown entrances at different levels and the long and highly ramified cave system.…”

Section: Introductionmentioning

confidence: 95%

The role of cave ventilation in governing cave air temperature and radon levels (Postojna Cave, Slovenia)

Gregorič

Vaupotič

Šebela

2013

Intl Journal of Climatology

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Radon concentration and cave temperature were studied at two morphologically different locations (the Beautiful Caves -BC and the lowest point -LP) in Postojna Cave (Slovenia). Radon concentration was considered a trace gas for cave ventilation research, where cave temperature was used as a supported microclimatic parameter. The influence of several climatic factors on radon concentration was studied, from which outside air temperature was found to have the highest control over cave ventilation. Measured radon concentration during 1-year period was in the range from 740 to 4000 Bq m −3 at LP, whereas during 2-year period at BC radon concentration experienced two different annual cycles. The change was observed after flood in September 2010. Radon concentration was in the range from 500 to 9000 Bq m −3 in the year 2010 and 500 to 5500 Bq m −3 in the year 2011 and 2012. Temperature was in the range from 9.9 to 10.5• C and 9.8 to 10.7• C at BC and BC-1 (the main passage connected to the LP), respectively. Two different ventilation regimes can be distinguished for LP location and for year 2010 at BC, whereas after flood, three ventilation regimes are characteristic for BC location. Significant change of radon emissions was observed after flood.

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Section: Introductionmentioning

confidence: 95%

The role of cave ventilation in governing cave air temperature and radon levels (Postojna Cave, Slovenia)

Gregorič

Vaupotič

Šebela

2013

Intl Journal of Climatology

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“…Minute quantities of uranium ( 238 U) present in limestone result in relatively high values of radon in karstic caves (Cigna, 2005;Gillmore et al, 2002;Hakl et al, 1997) due to the low natural ventilation of the underground cavities. Tectonic faults constitute an additional source of radon (Ball et al, 1991;Gillmore et al, 2000;Sebela et al, 2010). Variations of radon concentration in cave air arise from a balance of the emission from cave surfaces and drip waters, decay in cave air, and exchange with the outside atmosphere (Wilkening and Watkins, 1976).…”

Section: Introductionmentioning

confidence: 99%

Dependence of radon levels in Postojna Cave on outside air temperature

Gregorič¹,

Zidanšek²,

Vaupotič

2011

Nat. Hazards Earth Syst. Sci.

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Abstract. Postojna Cave is the largest of 21 show caves in Slovenia. The radon concentration there was measured continuously in the Great Mountain hall from July 2005 to October 2009 and ranged from about 200 Bq m −3 in winter to about 3 kBq m −3 in summer. The observed seasonal pattern of radon concentration is governed by air movement due to the difference in external and internal air densities, controlled mainly by air temperature. The cave behaves as a large chimney and in the cold period, the warmer cave air is released vertically through cracks and fissures to the colder outside atmosphere, enabling the inflow of fresh air with low radon levels. In summer the ventilation is minimal or reversed and the air flows from the higher to the lower openings of the cave. Our calculations have shown that the effect of the difference between outside and cave air temperatures on radon concentration is delayed for four days, presumably because of the distance of the measurement point from the lower entrance (ca. 2 km). A model developed for predicting radon concentration on the basis of outside air temperature has been checked and found to be successful.

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“…3). The position was selected in the close vicinity of a TM 71 extensiometer that has been detecting micro-tectonic displacements since 2004 (Gosar et al 2009;Šebela et al 2010) and where electricity was available.…”

Section: Resultsmentioning

confidence: 99%

Seismic Noise and Temporary Seismological Measurements in the Postojna Cave System

Živčić

Costa

Suhadolc

et al. 2014

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Karst caves are suitable places for seismological measurements because they are situated under the surface and often have lower seismic noise than locations on the surface. The idea to establish the first underground seismological station in Slovenia has led us to make preliminary seismic noise measurements in Črna Jama (part of the Postojna Cave System) in 2007. In search for further suitable stable places within the cave, we next performed seismic noise measurements, followed by a temporary accelerometer installation, near the highest point of the Velika Gora chamber in the first half of 2010. Since 7 May 2010, the seismic station is located inside the 9 m long artificial tunnel that was built for geophysical measurement purposes in Tar The aim of this study is the installation of a permanent seismic station inside the Postojna Cave System and future real-time integration of the related seismological data within the Slovenian and Italian seismological networks.

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Direct measurement of present-day tectonic movement and associated radon flux in Postojna Cave, Slovenia

Abstract: Micro-tectonic deformations have been monitored continuously in 3D in Postojna Cave, Slovenia with TM 71 extensometers since 2004. Two instruments, 260 m apart, were installed on the Dinaric oriented (NW-SE) fault zone that is situated about

Cited by 35 publications

References 24 publications

The role of cave ventilation in governing cave air temperature and radon levels (Postojna Cave, Slovenia)

The role of cave ventilation in governing cave air temperature and radon levels (Postojna Cave, Slovenia)

Dependence of radon levels in Postojna Cave on outside air temperature

Seismic Noise and Temporary Seismological Measurements in the Postojna Cave System

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