In May 2026, the Geodynamic Institute of the National Observatory of Athens installed a temporary high-sensitivity seismic station at OAKA, with the exclusive purpose of recording and studying vibrations caused by large music events and mass audience participation.

The station operated during the concerts of Metallica (May 9, 2026) and Iron Maiden (May 23, 2026), as well as during the EuroLeague Final Four final between Olympiacos and Real Madrid (May 24, 2026), continuously recording the tiny ground movements caused by tens of thousands of spectators. The recordings showed that the intensity and participation of the crowd are clearly reflected in the seismic data, allowing even the correlation of specific peaks with individual songs of the setlist.

The analysis of the data showed that the Metallica concert produced significantly stronger ground vibrations compared to Iron Maiden. The maximum recorded accelerations were about two and a half times greater, while the total seismic energy recorded corresponds to an equivalent local magnitude of approximately ML 1.5 for Metallica and ML 0.9 for Iron Maiden.

Although these values do not correspond to real earthquakes, they are a useful way of quantifying and comparing the intensity of the vibrations caused by the audience. The higher acceleration recorded at the Metallica concert is linked to the larger and more active crowd, which transferred significantly more energy to the ground compared to the Iron Maiden concert.

From the analysis of the seismic recordings, it emerges that the song that caused the greatest seismic response at the Metallica concert was “Moth Into Flame”, during which the highest value of ground acceleration was recorded. High values were also recorded during “Master of Puppets”, “Fade to Black”, “Wherever I May Roam”, and “One”.

Similarly, at the Iron Maiden concert the greatest seismic response was observed in “Killers”, while strong audience participation was also recorded in “2 Minutes to Midnight”, “Seventh Son of a Seventh Son”, “Rime of the Ancient Mariner”, and “Wrathchild”.

The comparison of the recordings shows that the Metallica concert at OAKA produced clearly higher peak seismic acceleration compared to Iron Maiden, a fact also reflected in the higher equivalent local magnitude (ML) calculated.

The more intense and more synchronized movement of the crowd at Metallica resulted in accelerations approximately two to three times higher than those of Iron Maiden, resulting in an ML of around ~1.3–1.5 versus ~0.8–1.0. Although these values do not correspond to actual seismic activity, they provide a useful measure for comparing the energy transferred to the ground and highlight the ability of seismographs to record large-scale human-induced vibrations.

What the seismic station recorded during the EuroLeague final

In addition to the two major concerts, the temporary seismic station also operated during the EuroLeague Final Four final at OAKA. The recordings showed that fans’ reactions during critical phases of the game, and especially during the trophy ceremony, created clearly detectable seismic signals. Although vibration levels were generally lower than those recorded at the Metallica concert, they were comparable to those of the Iron Maiden concert, highlighting the significant role collective human behavior plays in generating measurable ground vibrations.

This activity is part of the so-called “crowd seismology”. The results highlight the potential of seismology to record not only natural phenomena, but also the impact of human activity on the environment, turning two of the biggest music events of the year into a unique field scientific experiment.

The two concerts at OAKA functioned as a large-scale natural laboratory, where the temporary installation of the seismic station allowed the Geodynamic Institute to study how collective movement, rhythm, and the enthusiasm of tens of thousands of spectators are transformed into measurable seismic signals. The results offer a rare opportunity to explore the interaction between human gatherings and ground response, bridging scientific observation with live music experience in an impressive way and highlighting the importance of seismology as a tool for understanding broader environmental dynamics.