Tonga Tsunami at Timaru 

Data kindly supplied by PrimePort Timaru

Commentary

Timaru is on the open coast and is strongly affected by far infra gravity ( FIG ) waves. However, FIG waves tend to have periods of around 10 minutes, so the long-period waves that start about noon are most likely to be the tsunami. Unfortunately, the instrument failed on 5 May, trucating the record.

Figure 1. Tonga tsunami at Timaru showing: A. long wave record; B. significant (red) and maximum (blue) wave heights, and high tide times (green diamonds); C. period of significant waves; and D. distribution of significant wave height with time and period. EQ denotes the time of the earthquake. Times are in NZST (UTC + 12).

How were these calculated?
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