Bony et al. published an interesting study in Quaternary International about a Byzantine harbour (Theodosian harbour) which has been uncovered during excavations in Istanbul. The stratigraphic sequence goes back to 7000 BP. In the marine part of the sedimentary sequence, the authors interpreted high-energy deposit as tsunami deposits and related to the earthquake of 557 AD. You can find more info at http://dx.doi.org/10.1016/j.quaint.2011.03.031.