A recent archaeological dig at Te Ahua pa above Mercer Bay found a plethora of artefacts and materials that add to our knowledge of how Maori lived around Piha in the mid to late 15th century (…) Evidence suggests there was at least one tsunami in the 15th century and the archaeologists postulate that this may have been the cause of these ancient people choosing to live so high above sea level.

Kirkasukken: buried dead (as distinguished from those who have a watery grave – those drowned at sea) Shetland
(Robert Macfarlane, Landmarks 2015)