The Grotta Gigante Model (GGM) Печать
08.12.2014 14:33

A. Fabbricatore
Manager of the Grotta Gigante and of the Museo scientifico speleologico della Grotta Gigante (CAI-SAG TRIESTE)
Grotta Gigante, Borgo Grotta Gigante 42 - 34010 Sgonico (Trieste), Italy
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The Grotta Gigante Model is a state-of-the-art management model which aims at achieving an environmentally-friendly tourist development of the delicate underground ecosystem of the Grotta Gigante through technical and scientific professional skills.

This Model is a concrete example of effective synergy between science and culture, thanks to the ongoing collaboration with the Università degli Studi di Trieste, the Osservatorio Meteorologico Regionale (OSMER-ARPA), the Istituto Nazionale di Oceanografia e Geofisica Sperimentale (O.G.S.), the Museo Civico di Storia Naturale di Trieste, the Civici musei di storia ed arte di Trieste, the Soprintendenza Archeologica e per i Beni Ambientali, Architettonici, Artistici e Storici del FVG and foreign institutions, academies and universities. Synergy between science and culture but also with the tourist offer, supported by the cooperation with the Agenzia regionale Turismo FVG, the Tourist Consortiums, both local (PromoTrieste) and regional, as well as national and international tour operators.
Caves in general are a window into the past of the Earth enabling us to look into the future. Based on this assumption, the Grotta Gigante Model wishes to both contribute to the development of underground scientific research (defined as Naturwissenschaft by Hubert Trimmel) and sensitise the thousands of people visiting the Grotta Gigante every year to the issues related to the underground world.
Objectives of the Grotta Gigante Model. The Grotta Gigante was not explored by chance: the first documented exploration dates back to 1840 by engineer Anton Friedrich Lindner during his search for the river Timavo water to be used for the Trieste waterworks. Lindner did not find water on the bottom of the Grotta Gigante; however, he started a series of systematic studies that are still ongoing. As early as 1897 biological, palaeontological and meteorological study campaigns were reported, carried out by G.A. Perko, who said about the Grotta Gigante: “ lacks no grandeur, magnificence or scientific interest”. The first archaeological investigations in the Grotta Gigante were performed by Ludwig Karl Moser and date back to 1897.
At the same time the Club Touristi Triestini acquired the parcels on which the two entrances to the Grotta Gigante are found and, after a few years’ work to build the steps that still lead to the bottom of the Grotta, in 1908 the cave was opened to tourists. From then on, the Grotta Gigante has always been open to the public with a total of 3,759,006 visitors at 31 December 2013.
The positive combination of science and tourism lead to the installation, in 1959, of a pair of horizontal pendulums and to the opening of the Museo speleologico della Grotta Gigante (Grotta Gigante Speleological Museum) in 1963, the first of its kind in Italy.
Analysing the past 20 years of tourist history of the Grotta Gigante, it appears that the end-of-century tensions between underground scientific research and the needs of a tourism which was still linked to the indiscriminate exploitation of natural resources, typical of the 60s, have been replaced by a synergy between science and tourism leading to the definition of the Grotta Gigante Model.
The Grotta Gigante Model aims at marrying the requirements of underground scientific research and the need to spread scientific culture as the basis of a conscious and environmentally sustainable tourism, in order to hand down the cave to future generations as part of the natural heritage.
Scientific research and environmental monitoring. Show caves are the only chance for non-speleologists to get to know, see and understand the processes and forms of nature developing
underground. Thanks to their accessibility, show caves are also the ideal environment to carry out scientific research.
The Grotta Gigante, thanks to its collaboration with the University of Trieste first and all the other local scientific institutions later, has developed a state-of-the-art underground research model on an international level.
Geodetic pendulums. The processing and interpretation of the data used for the study of the Earth’s free oscillations, earth tides, local tectonic movements and major earthquakes are carried out by the Dipartimento di Matematica e Geoscienze of the Università degli Studi di Trieste with the cooperation of the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The building housing the pendulums, at the bottom of the cave, also holds the clinometers for the monitoring of the rotation around the horizontal axis of the Grotta Gigante.
The large size of the pendulums, whose upper and lower mountings are at a distance of 95 m, enables them to detect tectonic deformation with high precision and naturally removes some of the noise sources which typically affect smaller instruments. The study of the pendulums’ movements has enabled to recognise the Earth’s free oscillations, the long-term tilting of the Grotta in the North-West direction, the loading effect of the marine tides of the Adriatic, as well as the deformation caused by the underground floods of the river Timavo. These pendulums are the only instruments to have recorded four of the five largest earthquakes in the last 50 years: the 1960 Great Chilean Earthquake (the greatest earthquake ever recorded) and the 2010 Chile Earthquake (the fifth world-wide megathrust earthquake), the 2004 Sumatra-Andaman earthquake (third largest quake) and the one in Japan in 2011 (fourth largest quake), allowing an absolute-amplitude comparison of these events. The amplitudes of the Earth’s free oscillations are fundamental for the correct calculation of the extent of megathrust earthquakes since in these cases seismic waves represent the event only partially.
We are delighted to announce that the 18th International Symposium on Earth Tides by the International Association of Geodesy - Sub Commission 3.1 Earth Tides and Geodynamics will be held in Trieste in June 2016, thanks to the cooperation between the Dipartimento di Matematica e Geoscienze of the Università degli Studi di Trieste and the Grotta Gigante.
Underground hydrology. The Grotta Gigante is an important window into the hydrology of the Classical Karst thanks to the exploration of a series of wells intercepting the groundwater of the Classical Karst down to a depth of -252 m below the entrance height, i.e. 25 m.a.s.l.
The Dipartimento di Matematica e Geoscienze of the Università degli Studi di Trieste carries out continuous monitoring of the waters filling the cavities during and after precipitation, cavities within the limestone rock mass which has been undergoing karst dissolution for millions of years. These instruments are part of a network monitoring the Karst waters from the sink of the Reka River in the Škocjanske jame (Slovenia, about 30 km S-E of the Grotta Gigante) to the Timavo springs of San Giovanni di Duino (Italy, about 10 km N-W of the Grotta Gigante). These waters, whose underground course is known only in specific points (at the bottom of caves such as the Kačna jama, Stršinkina jama, and Kanjeduce jama in Slovenia and the Abisso di Trebiciano, Grotta meravigliosa di Lazzaro Jerko and Grotta Skilan in Italy), flow very slowly under normal conditions, yet at a speed of 23 cm/sec during flood events.
The Grotta Gigante is part of the monitoring network because during the major flood events the water reaches and goes beyond the bottom of the series of side wells of the cave (Pozzo Coloni).
In December 2009 a CTD DIVER was installed in the deepest part of the cave (252 m deep) to continuously measure the level of water, temperature and electrical conductivity: on two occasions an increase of over 30 m in the level of water was recorded.
Seismographic measurements. In 1963 the Centro di Ricerche sismologiche of the Istituto Nazionale di Oceanografia e di Geofisica sperimentale (OGS) installed a seismographic station. The instruments were installed by the Servizio geologico degli Stati Uniti in accordance with the 120 stations of the World-Wide Standard Seismographic Network (WWSSN) scattered across all continents.
In 1996 the WWSSN instruments were discarded and replaced by 3 digital Streckeisen broad-band
The Grotta Gigante currently houses the Trieste “TRI” station of the MedNet network, owned by the Istituto Nazionale di Oceanografia e Geofisica Sperimentale (OGS) and the Dipartimento di Matematica e Geoscienze of the University of Trieste, which includes modern digital Streckeisen broad-band sensors used both for local seismic warning (thanks to the live connection with the Protezione Civile Friuli Venezia Giulia) and for the recording of distant events. All data are acquired by OGS for storage, study and world-wide transfer.
The basement of the Grotta Gigante Visitors Centre, in close contact with the underlying limestone rock, houses the Trieste monitoring station of the Friuli Experimental Seismic Network (FESN), regional branch of the national Italian Experimental Seismic Network (IESN), in charge of recording local events, which are then stored at the headquarters of the Protezione Civile Friuli Venezia Giulia together with the data from the other stations of the network.
Flora. The Dipartimento di Scienze della vita of the University of Trieste monitors the flora at the mouth of the Grotta, and carries out an important inspection and prevention activity inside the cave in order to limit the proliferation of Lampenfora.
Fauna. As regards the cave’s fauna, researches carried out since 1895 have shown the presence of about forty different species, which make the Grotta Gigante one of the richest and most investigated caves of the Trieste Karst. Recent researches carried out by the Museo Civico di Storia naturale of Trieste have confirmed the compatibility between the tourist use of the cave and the presence of specialised cave fauna.
Radon. A high concentration of Rn -222 has been recorded in many Karst caves all over the world. In order to monitor the trend all over the year different types of surveys were carried out:
a. short-term measurements with E-Perm electrets (Electret Ion Chamber EIC) to study the distribution of radon concentration in the cave;
b. long-term measurements with active RAD -7 instruments to study the radon concentration trend all over the year;
c. the correlation of radon concentration with the cave’s internal and external temperature and other parameters.
In summer 2010 radon concentrations above 20,000 Bq/m3 were measured in a non-tourist area of the cave. In the same place, radon concentrations below 100 Bq/m3 were detected in wintertime.
The Friuli Venezia Giulia Regional Agency for Environmental Protection, in cooperation with the Dipartimento di Matematica e Geoscienze of the University of Trieste studies the radon trend within the Grotta Gigante.
Here the annual average values are around 350 Bq/m3, i.e. below 500 Bq/m3 which is the limit imposed by the Italian regulations in force. Another study, conducted both using a high number of electrets, some of which located far away from the tourist path, and using a continuous-recording active instrument (Rad 7) with hourly sampling, revealed:
a. big differences in concentration from one area to the other of the cave, with higher values (sometimes by several magnitudes) inside branches and secondary tunnels that are not reached by the tourist path, compared to the measurements taken inside the main cavity;
b. a marked seasonality, especially in the above-mentioned areas with a higher concentration, with peak values above 30 kBq/m3 in summertime and around 100 Bq/m3 on average in wintertime;
c. the presence of sudden, marked oscillations in the Rad 7 values in those areas and time frames in which the highest concentration levels were measured.
In particular, decreases of approx. 10-15 kBq/m3 over 4-6 hours were recorded, followed by similarly sudden increases able to restore the initial conditions in about the same time.
Laser scanner 3d survey. In order to precisely define the size and shape of the Grotta and produce videos and 3D models, an aerial LIDAR survey was carried out so as to frame the area of interest and define the topographic surface with centimetric precision. A laser scanner survey was conducted in the cave during which 4.5 billion points were recorded with sub-centimetric precision and an average density of 10,000 points/sq m. The processing and analysis of the collected data enabled to define with absolute precision the cave’s measurements.
It was therefore possible to transfer the georeferenced survey of the Grotta Gigante both to orthophotos and cadastral maps on a 1:1000 scale.
Gravimetry and geoelectrics. Thanks to the use of modern GPS technology, the Dipartimento di Matematica e Geoscienze of the Università degli Studi di Trieste, in cooperation with the Istituto Nazionale di Oceanografia e di Geofisica sperimentale (OGS), was able to complete the gravimetric measurements taken at the Borgo Grotta Gigante site.
A geoelectric prospection campaign is now in progress, which has revealed a number of anomalies.
Karstifiable rock erosion. Measurements of the surface dissolution of carbonate rocks are carried out by the Dipartimento di Matematica e Geoscienze of the University of Trieste in the first experimental station located in the outbuilding of the Grotta Gigante Visitors Centre. Measurements are taken using a special instrument developed by researchers from Trieste, the micro-erosion meter. Readings are taken at regular intervals; the average limestone rock erosion since 1980 is approx. 0.02-0.03 mm/year, i.e. an overall reduction of almost 1 mm over 30 years.
Meteorology and climate. From 1 January 1967 meteorology and climate have been monitored by the Borgo Grotta Gigante Meteorological Station, which is currently classified as a Climatological Observatory. In 2007 the site entered the Meteorological Network of Friuli Venezia Giulia and the Trans-European network for the monitoring of Local Severe Weather phenomena. Furthermore, the Servizio idraulica of the Friuli Venezia Giulia region has installed rain gauges in order to monitor the rainfall. At the bottom of the Grotta Gigante a temperature sensor has been installed equipped with an internal micro-processor for function monitoring, data pre-processing, A/D conversion of electrical signals, etc. These features ensure highly accurate and reliable data.
Particulate matter. The sampling of atmospheric particulate matter (PM) and volatile organic compounds (VOCs) is carried out by the University of Trieste in the aboveground site opposite the entrance to the Grotta Gigante.
Thanks to a newly developed analytical method it was possible to detect, within the PM, small organic molecules derived from atmospheric oxidation of volatile species released by plants that, due to their origin, are called biogenic secondary organic aerosols (BSOA).
Nature education tourism (n.e.t.). The Grotta Gigante has developed a nature tourism network in the territory of the Gulf of Trieste called N.E.T. - Nature Education Tourism.
The members of the N.E.T are: Grotta Gigante, Museo civico di Storia naturale, Civico Acquario marino - Orto botanico - Museo del mare, Museo nazionale dell’Antartide, WWF Area marina protetta di Miramare, Giardino botanico Carsiana, Riserva naturale regionale Isola della Cona.
Findings. In the Grotta Gigante, which opens into ultrapure Cretaceous limestone, many fossil findings (Rudists) were discovered.
Excavations in a small gallery led to discovery of palaeontological remains such as the Ursus spelaeus, the Rhinoceros, the Bos Primigenius, and archaeological finds dating from the Neolithic to the Bronze Age.
All the fossil and archaeological findings, as well as others coming from the area surrounding Borgo Grotta Gigante, are on display at the Museo scientifico speleologico of the Grotta Gigante, created in cooperation with the Università degli Studi di Trieste, the O.G.S. (Istituto Nazionale di Oceanografia e Geofisica Sperimentale), the Museo Civico di Storia Naturale of Trieste, the Soprintendenza Archeologica e per i Beni Ambientali, Architettonici, Artistici e Storici del FVG and the Civici musei di storia ed Arte di Trieste.
Cooperation with foreign bodies and institutions. The Grotta Gigante has adopted a systematic approach by establishing effective cooperation with prestigious foreign institutions and universities such as the Naturhistorisches Museum Wien (Austria), the Notranjski muzej of Postojna (Slovenia), the Ruhr-Universität of Bochum (Germany) and the National Antarctic Scientific Centre (N.A.S.C.). The latter carried out pilot measurements inside the Grotta Gigante consisting in a series of observations including gamma dosimetry, gamma spectrometry and radon measurements in cooperation with the ZRC SAZU Karst Research Institute of Postojna (Slovenia), the IJS Istituto Jožef Stefan, Ljubljana (Slovenia), the NASC (Ukraine) and with the support of the RPE AtomKomplexPrylad (Ukraine).
Tourism environment research. The cultural heritage created by the Grotta Gigante in over
100 years of scientific research activity necessarily had to be offered to tourists with a systematic approach enabling to connect a conscious tourism with the natural environment of the cave and with the popularisation of scientific culture.
Innovation was essential in order to ensure users (rather than tourists or mere visitors) a higher quality by offering rewarding experiences thanks to innovative services enabling to make the most of the site.
The Visitors Centre, whose structure blends in with the surrounding Karst environment, was inaugurated in December 2005. The choice of construction types and materials was made according to their environmental impact and eco-compatibility, the building tradition of this specific area and the requirements of the users. The environmental and landscape restoration of the Grotta Gigante green spaces was also deemed necessary.
In 2009 the cave’s electrical system was remade to comply with the regulations in force taking into account energy saving and scenery with the enhancement of the natural concretions and colours of the Grotta.
Technological innovation could not be neglected, which is why the Visitors Centre as well as the entire underground route were equipped with wifi connection. Thanks to digital devices you can connect via videoconference from inside the cave and show live the spectacular view you are experiencing. Believing in the use of technology in all its forms, the Grotta Gigante could not avoid relying on Tripadvisor to be publicly assessed by its users. The cave is also present on all social networks (Facebook, Twitter, YouTube, Foursquare, Instagram) and its website is constantly updated.

Fig. 1. Grotta Gigante, Italy: Laser scanning image. The visitor centre of the Grotta Gigante, the entrance to the cave and the beginning of the tourist path: the steps welded into steel railways tracks forged at the beginning of the 20th cent. in Austria.

Fig. 2. la Grande Caverna, height 98.50 m, volume 365,000.00 mc (photo by Alessio Fabbricatore)

Fig. 3. la Grande Caverna, the stalagmites have the shape of a pile of plate, a consequence of the splash dripping from a great height
(photo by Alessio Fabbricatore)

Considering the cave’s remarkable background, a tourist model in line both with previous strategies and the European strategy was developed, drawing on the concepts of sustainability, services, enhancement of territorial and natural resources and centring around visitors and their interests and expectations. The Grotta Gigante is constantly and dynamically seeking to provide visitors with experiences and good reasons for experiencing the cave tour with active participation.
In order to meet these goals, it is necessary to offer an added value such as the one represented by special tours, educational geology workshops focusing on Karst phenomena, underground biology, seismology, and mainly aimed at schools so that school trips can actually turn into educational visits for pupils and refresher courses for teachers. The Museo scientifico speleologico della Grotta Gigante is our latest proposal, enabling to discover various Karst phenomena and to visit the archaeological sites where the displayed finds were discovered, as well as geological phenomena of international interest.
The Grotta Gigante can be classified as a competitive, integrated system of great attraction and sustainability enhancing its visit and offering a tourist product of excellence which differs according to the users’ requirements.
In order to reach these goals, the cave created a network with scientific research bodies and other local historical and environmental institutions, as well as with local companies (in the food-and-wine sector) and inbound tour operators.
Of great importance the unique and continuous statistical monitoring of the visitors’ presence, from the opening of the cave back in 1908 to the present; in actual fact, the Grotta Gigante is the oldest regional tourist site and has been open to the public continuously since 1908.
The important partnership with Turismo FVG, PromoTrieste and the regional tourist consortiums has lead the Grotta Gigante to develop marketing strategies ranging from the participation in trade fairs, both in Italy and abroad, and workshops to digital and social media marketing, as well as the distribution of promotional material aiming at giving useful information about the site and how to reach it, without forgetting the organisation of international events that are promoted through the digital network so as to reach all segments of the international tourist market.
Finally, the staff is constantly updated both from a scientific point of view and as regards the reception of tourists.