Reassessing the Mycenaean Earthquake Hypothesis: Results of the HERACLES Project from Tiryns and Midea, Greece

Observations at Mycenaean archaeological sites of tilted and curved walls, broken pottery, and human skeletons led to the hypothesis that these sites in the Argolid, Peloponnese, Greece, were destroyed in large earthquakes between the late palatial (thirteenth century B.C.E.) and postpalatial (1200-1050 B.C.E.) periods. In particular, the destruction of Mycenaean palaces around 1200/1190 B.C.E. has often been attributed to a devastating earthquake. To test the Mycenaean earthquake hypothesis, this project focuses on the Argive citadels of Tiryns and Midea. With active and passive seismic measurements complemented by a gravimetric survey, we explored seismic site effects at these locations and calculated synthetic seismograms for potential earthquake sources to estimate intensities of ground motions inside and outside the citadels. The field work and results were supplemented by analysis of the individual damage descriptions and observations from the archaeological literature on which the hypothesis is based. Because of poor construction techniques and the associated site effects, the buildings in the Lower Town surrounding the citadel of Tiryns were more vulnerable than the structures within the Cyclopean palace walls, but evidence of an earthquake destruction stratum in the Lower Town has not yet been found. Although some of the observations from the two investigated citadels could be explained by seismic loading, alternative nonseismic causes could equally explain most observed damage. In some cases, the structural damage was clearly not caused by earthquakes. Simulated ground motions show that severe earthquake damage at Tiryns and Midea can be expected from activation of local faults in the Argive basin; however, palaeoseismic studies for such activity in and since the Late Bronze Age (LBA) are lacking. Our results indicate that the hypothesis of a destructive earthquake in Tiryns and Midea, which may have contributed to the end of the LBA Mycenaean palatial period, is unlikely.