A big non-event, like bird flu, swine flu, ...
It is true that tsunamis gain elevation in shallow water. In deep water they have a small amplitude, very long wavelength (as much as hundreds of km) and high speed. As the depth decreases they slow down and pile up, the wavelength decreases.
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But it has to be a big-wave event to have power ten thousand km away from the epicentre, and the absence of big wave activity on the coast of S America made it obvious after a couple of hours that this was not the case. A big earthquake does not equate to a big tsunami, it depends how the fault moved - there has to be motion in a vertical direction to disturb the water.
I did know Pia Raudkivi (and Peter and Paavo) when I was growing up. I've only seen Pia a couple of times since then. A bright girl, a bit of a tomboy in those days. Paavo was the really bright one, first in his year at engineering school, and a good musician (he studied jazz piano). His father was very disappointed when he threw it in after graduating and went to NY to manage restaurants. He certainly had no intention of following in his father's footsteps.
Don't worry about Taupo erupting, it probably won't happen in our lifetime. ;-) Speaking of Taupo, I learned a very interesting fact about those eruptions a few years ago, speaking to a geologist. It seems that source of a piece of rock can be identified from its elemental composition, which is a kind of chemical fingerprint, and it is known that the west coast black sand all comes from eruptions at Taupo and, to a lesser degree, Taranaki. As you know the prevailing wind on the west coast is the south-wester, creating waves that tend to approach the beach from the south side of the shore normal, leading to upcoast sand transport. The sand from Taupo has been transported on the surfzone conveyer all the way up to Cape Reinga. On the way it created the vast Kaipara Harbour - both heads are made of sand. Sand crosses the harbour mouths along the sand bars. Most beach sand is underwater, by the way.
No, I can take no credit for the Mission Bay and Kohi beaches. The coastal work I did on beach evolution was all in California. In NZ my only coastal projects have been in modelling flows and transport (sediment and effluent) in the Auckland harbours. I have a model for tidally-forced flow in the Hauraki gulf that extends from outside Gt Barrier Is. to the upper reaches of the Waitemata. But that's all water under the fridge.
PS I was out at Whatipu yesterday, amidst all that sand. What a beautiful spot! Over the years I've been going there there has been a tremendous amount of change. The sand is constantly in motion, the beach grows, contracts, there is no such thing as equilibrium. It is like global climate in microcosm. |
