Prehistoric chamber tombs or geological pitfall? A multimethod case study from Ancient Aigeira with a focus on seismic full‐waveform inversion

We show an extensive multimethod geophysical study of focusing on someenigmatic subsurface structures found at Ancient Aigeira (N Peloponnes, Greece) thatcould be interpreted either as prehistoric chamber tombs or complex weatheringpatterns of the local marl–conglomerate rock sequences. It turns out that the non-seismic methods do not allow to distinguish between an archaeological and a geologi-cal origin of the observed patterns with certainty. In contrast, we demonstrate howshear-wave seismics and full-waveform inversion (FWI) can be used in archaeologicalprospection for distinguishing between these alternative essentially differentinterpretational models that are not distinguishable through nonseismic prospectiondata. The example site Aigeira is strategically well located on a hill on the NorthernPeloponnese overlooking the Corinthian Gulf and has been inhabited with occupa-tional gaps since Middle Neolithic times until the 12th to early 14th centuryCE.Magnetics, ground-penetrating radar (GPR) and electrical resistivity tomography(ERT) reveal a honeycomb-shaped anomaly pattern that could have been interpretedas a system of prehistoric chamber tombs. The time-domain SH-FWI strategy basedon a sequential inversion of low-pass and band-pass filtered data results insubsurface models for shear-wave velocity and density that accurately fits the com-plicated seismic data set.With the help of the seismic survey, we can reject the interpretationhypothesis of a prehistoric cemetery with chamber tombs and confirm that theenigmatic geophysical patterns represent a geological weathering structure thatcould be addressed as a reincised fan delta draped by reddish palaeosols.