Dorothy Mckenzie, of Herbert, asks :-
Is there any possibility that a tsunami hit the North Otago coast in the wake of the Napier earthquake in Feb 1931?
I realize that is a long time ago, but I have often wondered about that, because I was born in Oamaru on Jan 29th, just a few days before the quake. My mother always told the story that when people came to visit her (she was there for two weeks in those days) all talked about the exceptionally high tides and the rough seas. I have checked the local papers of the time, but could find nothing exceptional, so was it just coincidence?
Mark Stirling, a seismologist at the University of Otago's Geology department, responded.
I do not know of any tsunami being produced by the 1931 Napier earthquake, even in areas close to the epicentre. The earthquake was certainly large enough to produce a tsunami in the right circumstances, but the circumstances were not right. It ruptured under both land and sea, which means the rupture would have been ineffective for tsunami production over a significant part of its length. If it did not produce a tsunami locally, then it is even less likely to have produced one as far away as Oamaru. What your mother was seeing was probably just coincidence. Bad weather swell or something to that effect.