Tonga Tsunami at Port Taranaki 

Data kindly supplied by Westgate Transport Ltd

Commentary

Port Taranaki is exposed to the high energy Tasman Sea. Strong far infra gravity ( FIG ) and infra gravity ( IG ) waves occur regularly. The period leading up to the tsunami was uncharacteristically quiet. The tsunami excited the 15-minute seiche-period of the embayment. The waves started arriving about 7 hours after the earthquake and peaked about 9 hours after the earthquake. Subsequently, a small FIG event occurred that obscured the tsunami waves.

Figure 1. Tonga tsunami at Newton King Wharf, Port Taranaki 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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