Speaker
Description
The Esztramos Hill, located in the northeast of Hungary, is a small hill that is a member of the Aggtelek Karst, and is mostly made up of dolomite and limestone. On the boundary of these two rock formations a deposite of iron ore formed that reached up to the current surface. From the early 19th up until the late 20th century this ore deposit was subject to mining operations on several levels of the hill, until the deposite was almost entirely depleted. At the late stages of mining a limestone quarry was opened on top of the hill, that left a large part of its surface flat and exposed. The hill now hosts a large cave-mine complex with interconnecting tunnels of the abandoned mine and multiple cave systems [1].
Our research group at the HUN-REN Wigner RCP has been conducting muographic measurements at the lowest level of this complex for years. There are three main drifts there that have each hosted multiple measurement positions so far. We currently have 3 MWPC [2] type muograph detectors operating inside the hill. Based on our measurements so far, we have been able to create a 3-D reconstruction of the position and extent of partially collapsed, inaccessible parts of the iron ore mine, and also detected a nearby void that could be caused by a previously unknown cave [3]. While exploring the known cave systems of Esztramos Hill, our muographs detected large density anomalies in the close proximity of the Rákóczi cave system, the main cave of which is part of the UNESCO World Heritage list [4]. In this presentation we will summarise the results of this extensive survey, including 2-D muograms and 3-D muographic inversion results.
[1]: Turtegin, E.: History of iron ore mining on the basis of archive records at the Esztramos Hill. Topogr. Minerol. Hung. V, 31–36 (1997).
[2]: Varga, D., Nyitrai, G., Hamar, G. & Oláh, L.: High efficiency gaseous tracking detector for cosmic muon radiography. Adv. High Energy Phys (2016).
[3]: Rábóczki, B., Surányi, G., Balázs, L., Hamar, G.: Void discovery inside Esztramos Hill using muographic methods. Sci Rep 15, 33394 (2025).
[4]: UNESCO World Heritage List: Caves of Aggtelek Karst and Slovak Karst. https://whc.unesco.org/en/list/725/. Accessed 27 Feb 2026.