The Mediterranean is a zone of intense earthquake activity because the plates carrying Africa and Europe are slowly moving together, according to the theory of plate tectonics. Notable earthquakes in antiquity include: Sparta c.464 bce, where several thousands may have perished; Helice in Achaea 373 bce, where the city was submerged under the sea; Rhodes 227/6 bce, when the Colossus statue collapsed; Pompeii62 ce, which suffered severe damage. Some destructions of Mycenaean and Minoan palaces are also attributed to earthquakes. Earthquakes were associated with Poseidon in mythology: Poseidon the Homeric ‘earth-shaker’ (ennosigaios) was fervently worshipped also as ‘earth-holder’ (gaiaochos) and ‘stabilizer’ (asphalios), in Sparta and elsewhere. King Agesipolis of Sparta was as distinctly unusual in his pragmatic approach to an earthquake in the Argolis in 388 bce (XenophonHell. 4. 7. 4–5) as Herodotus (7. 129. 4) was in his rationalist, seismological explanation of Thessalian geomorphology (see thessaly). Ancient philosophers and ‘scientists’, however, frequently speculated about the causes of earthquakes (SenecaQNat. bk. 6). Thales thought that the earth moved upon the primeval waters. Anaximenes (1) reckoned that variations in wetness and aridity caused cracks in the earth. Several philosophers, including Anaxagoras, Democritus, Aristotle, and Posidonius (2), produced theories which involved water or air entering the earth and causing explosions.