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Samoa quake tsunami detected in Chatham Islands |
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Sep 30, 2009 at 02:57 PM |
The Geological and Nuclear Sciences (GNS) tsunami gauge at Kaingaroa
detected a small tsunami (~40 cm) originating from today's magnitude
8.3 earthquake near Samoa. Rather than being of short duration,
abnormal wave heights were recorded for more than three hours.
Dr Willem de Lange from the Department of Earth & Ocean Sciences at Waikao University said that "The Chatham Islands is exposed to a greater tsunami risk than most of New Zealand because the Chatham Rise acts as a wave guide to trap tsunami. The tsunami waves bounce back and forth along the Chatham Rise, resulting in larger waves at either end (The Chathams and Banks Peninsula). Also because of the deep water around the Chathams, they tend to get the tsunami waves first (Travel faster in deep water). This is why the Chathams were the first location where a tsunami warning gauge was installed. We discovered that the initial site at Waitangi was affected by the waves bouncing, which made them even larger at Waitangi. Hence, the gauges are now located at Kaingaroa, which gives a better indication of how large they will be for the rest of New Zealand".
For the latest charts visit www.geonet.org.nz/tsunami/gauges/
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Tsunami chart
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