Deadly CO2 Gases in the Plutonium of Hierapolis (Denizli, Turkey)
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Archaeological and Anthropological Sciences (2019) 11:1359–1371 https://doi.org/10.1007/s12520-018-0599-5 ORIGINAL PAPER Deadly CO2 gases in the Plutonium of Hierapolis (Denizli, Turkey) Hardy Pfanz1 & Galip Yüce2 & Ahmet H. Gulbay3 & Ali Gokgoz4 Received: 30 March 2016 /Accepted: 16 January 2018 /Published online: 12 February 2018 # Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Using a portable gas analyzer system, the geogenic gas regime below and around an ancient gate to hell at Hierapolis/Phrygia was characterized. The site was first described by Strabo and Plinius as a gate to the underworld. During centuries, it attracted even ancient tourists. In a grotto below the temple of Pluto, CO2 was found to be at deadly concentrations of up to 91%. Astonishingly, these vapors are still emitted in concentrations that nowadays kill insects, birds, and mammals. The concentrations of CO2 escaping from the mouth of the grotto to the outside atmosphere are still in the range of 4–53% CO2 depending on the height above ground level. They reach concentrations during the night that would easily kill even a human being within a minute. These emissions are thought to reflect the Hadean breath and/or the breath of the hellhound Kerberos guarding the entrance to hell. The origin of the geogenic CO2 is the still active seismic structure that crosses the old town of ancient Hierapolis as part of the Babadag fracture zone. Our measurements confirm the presence of geogenic CO2 in concentrations that explain ancient stories of killed bulls, rams, and songbirds during religious ceremonies. They also strongly corroborate that at least in the case of Hierapolis, ancient writers like Strabo or Plinius described a mystic phenomenon very exactly without much exaggeration. Two thousand years ago, only supernatural forces could explain these phenomena from Hadean depths whereas nowadays, modern techniques hint to the well-known phenomenon of geogenic CO2 degassing having mantle components with relatively higher helium and radon concentrations. Keywords Carbon dioxide . Helium . Radon . Charonion . Gate tohell . Geogenic gases . Hades . Mephiticexhalations . Mofette Introduction town, probably a Seleucid foundation in the second century B.C. (Gerster 2005 p. 162; Porter 2016 p. 355), developed The Pamukkale thermal province located in the east of the during the Roman Empire and was already famous in Buyuk Menderes Graben is famous for its thermal springs Byzantine times (Ring et al. 1995 p. 327; Rigsby 1996; and snow-white travertine formations and also for the excava- Cohen 2006; Zwingmann 2012; Nyquist 2014; Şimşek and tions of ancient Hierapolis. First recordings of the old city of D’Andrea 2017). In this period, a huge pilgrim sanctuary was Hierapolis were made by Strabo (XII, 8, 17) and also Plinius built around the tomb of the Apostle Philip (D’Andria 2003). the Elder (Nat. Hist. V, 105) mentions this famous town. The Geologically, the holy town Hierapolis is cut longitudinally by several parallel fractures of the Pamukkale fault (intra-plate tectonics) as the part of extensional straining of the western * Hardy Pfanz Anatolian extensional regime or the west Anatolian horst- [email protected] graben system extending from the Aegean Sea to central Anatolia (Seyitoglu and Scott 1996; Kaymakci 2006). It is 1 Institute of Applied Botany and Volcano Biology, University of specified mainly by major horsts and grabens at E–W trending, Duisburg-Essen, 45117 Essen, Germany and NW–SE to NE–SW oriented relatively short and locally 2 Department of Geological Engineering, Hacettepe University, suspended cross-grabens (Bozkurt 2003). Thus, Hierapolis is Beytepe, 06800 Ankara, Turkey situated in one of the most tectonically active regions of Asia 3 Department of Geological Engineering, Eskisehir Osmangazi Minor. Therefore, the area was destroyed several times by University, 26480 Meselik, Eskisehir, Turkey many earthquakes (Altunel and Barka 1996; Hancock and 4 Department of Geological Engineering, Pamukkale University, Altunel 1997; Altunel and Karabacak 2005;Kaymakci2006; Denizli, Turkey Uysaletal.2007, 2009;Keleetal.2011; Hancer 2013;De 1360 Archaeol Anthropol Sci (2019) 11:1359–1371 Filippis et al. 2012;Kumsaretal.2016). Directly build upon paralleling each other (cf. Özdemir 2002;Kaymakci2006; such a fault are two interesting buildings: the famous Apollo Hancer 2013;Kumsaretal.2016). Several buildings of temple and the newly discovered Plutonium, the sanctuary of Hierapolis were directly built on the fracture zone. Two buildings the Gods of the Underworld, Pluto and Kore, with the theater that were already mentioned by ancient writers for their Bdeadly above a grotto. The latter was excavated between 2011 and Hadean breath^ were selected for a close determination of 2013 during the campaign of the Italian Archaeological geogenic gas emissions: the Apollo temple and the newly exca- Mission in Hierapolis (D’Andria 2013). To be exact, this site vated sanctuary of Pluto (Fig. 1c; see also D’Andria 2013). has been mentioned by several antique sources as the entrance to the Underworld (Zwingmann 2012); they describe that Gas measurements strange things happened at this Hadean outlet which they called Plutonium (Ploutonium) or Charonium. Deadly vapors were Measurements were taken during two different campaigns in described escaping from these places (Strabo XIII, 4, 14; May 2013 and June 2014.The gas measurements were carried Bejor 1984). Priests were demonstrating their supernatural out with the portable gas analyzer GA2000 (Geotechnical power and their equality to the gods by ushering animals like Instruments, England; Pfanz et al. 2004) equipped with water goats and bulls into the grotto (Plutonium) where, after a short and dust filters. CO2,CO,CH4,H2S, and O2 were recorded time, the animals showed signs of suffocation, finally dying simultaneously. Problems occurred when the soil was wet, wa- after several minutes. Yet, the castrated priests (Galli) survived terlogged, or filled with hot water vapor, as liquid water would (Strabo XIII, 4, 14; Plinius, Nat. Hist. II, 207–208; for reviews, damage the sensitive cells of the analyzer. Polyethylene and see Zwingmann 2012 or Pfanz et al. 2014). Teflon tubing (1 cm in diameter) was used to enlarge the mea- Many similar sacred Greek and Roman places, oracles, and suring radius up to 6 m. Readings were recorded after several temples were often located directly above or close to geolog- seconds to one minute. Long-term measurements for CO2 were ical disturbance zones (Piccardi 2000;DeBoeretal.2001; made using a self-made CO2 analyzer,equippedwithanultra- Etiope et al. 2006; Foster and Lehoux 2007; Piccardi et al. low power (3.5 mW), non-dispersive infrared (NDIR) sensor 2008;Mariolakosetal.2010). The famous oracle of Delphi (measurement range of 0–100%; COZIR, CO2 Meter, Florida). was built on the intersection of two fracture zones where either The warm-up time of the sensor is shorter than 10 s; operating methane/ethylene venting or hypoxic aeration due to methane conditions are − 25 to 55 °C and 0–95% RH, non-condensing. or CO2 emission enabled Pythia to give her prophecies (De The accuracy of the sensor is ± 0.5% vol. CO2, at standard tem- Boer et al. 2001; Etiope et al. 2006; Piccardi et al. 2008). perature and pressure. The pressure dependence of the sensor is Heavy methane emissions were also found at Chimera 0.13% of the readings per millimeter of Hg. (Etiope et al. 2006; Hosgormez et al. 2008). In all cases, either The sensor was attached with a micro-diaphragm gas sample high CO2 concentrations or methane and other hydrocarbons pump (delivery, 0.4 l/min; KNF Neuberger, Balterswil, were emitted from geogenic sources (for a review, see Pfanz Switzerland). The sampling time was set with a microcomputer et al. 2014 and Etiope 2015). to 30 s. At the end of each interval, the measurement value was This paper accounts for the geochemical compositions of saved on a micro-SD card and the sensor and pump were pro- soil gas of some fractures and holes around the Hierapolis grammed to go to sleep mode until the next sampling cycle (after fault and Hierapolis archeological sites. We concentrated our 5 min). The battery-driven device was mounted within a water- survey specifically on the close vicinity of the Temple of tight hard plastic box. CO2 measurements at different heights Apollo and the Plutonium of ancient Hierapolis/Phrygia (15, 40, 100 cm) above the ground level within the sanctuary where mystic tales and narratives of the asphyxiation of bulls of Pluto were performed on different days in 2014. during religious ceremonies exist. We tried to (1) find and (2) In situ radon measurements were carried out by GEO-RTM quantify the noxious gas(es) inside and outside of the both 2128 alpha spectroscopy instrument. A Teflon tubing was temples and (3) examine the diurnal degassing patterns to help inserted 2–3 m into the mouth hole of the Apollo temple and understanding how ancient ceremonies were safely performed grotto of the Plutonium; it was directly connected with the radon by the priest of the sanctuaries. measurement chamber. The relative statistical error for radon activities ranged from over 10% for low radon values (∼ 2– 10 Bq l−1) to less than 5% for values greater than 10 Bq l−1. Material and methods The measurement period was selected as a minimum of 1 h to obtain reliable results with a high confidence level (95%). The The location isotopic composition of helium and neon was determined by mass spectrometry at INGV-Palermo. Two gas samples taken Hierapolis is located in the Denizli graben in the southwest of directly from the mouth of the grotto were collected by taking Turkey (Fig. 1a, b) which is a geological disturbance zone ex- care to avoid the least amount of atmospheric gas contamination. tending between the Pamukkale and Babadag faults that are The sampling procedure for free gases is as follows: free gases Archaeol Anthropol Sci (2019) 11:1359–1371 1361 Fig.