Tsunami alerts must be heeded

At 5.40am on the morning following the recent earthquake in Chile, bleeping pagers woke Coastguard Hibiscus crew with a tsunami warning and instructions to implement our full unit tsunami plan. Coastguard operations staff in Auckland had been broadcasting the tsunami warning through the night from 12.30am on all the Coastguard VHF radio channels and consulting with Auckland Civil Defence, the Harbourmaster and Maritime Police, preparing the Coastguard response to the tsunami threat to our coastline. Local units such as Coastguard Hibiscus had been left to sleep most of the night in preparation for what could be a very long day if coastal damage and risk to boaties and beachgoers turned out to be major.

Many concerned boaties, out for the weekend on the water, had contacted Coastguard seeking advice. I cannot stress enough that the indications of timing and severity are only best estimates and that tsunami waves can strike an hour or more before or after the predicted time and the following waves for a great number of hours afterwards, with the last wave usually the largest. This is why boaties and beachgoers are warned to stay away from the water and beaches, even when it’s a hot summer’s day.

The Coastguard Hibiscus tsunami plan calls for our boats to go out to deep water beyond Tiri and stand by. At 8am both our vessels headed for our designated stand by point, north east of Shag Rock, in 36m of water. En route, Hibiscus Rescue One and 2 approached all the other vessels we could see on the water close to land to ensure they were aware of the tsunami warning.

We advised these vessels of the predicted arrival time for the tsunami, 10.52am, and that they should move to at least 500m away from shore and remain in at least 20m of water at this time as per advice we received from Coastguard Northern Region based on the initially predicted tsunami wave height of one to three metres.

Hibiscus Rescue One and 2 then waited. Nothing significant was noticed in terms of a tidal wave. At 12pm Coastguard had another briefing with Civil Defence, after which we were stood down, but asked to remain on alert as the threat could continue for another 12 hours. The sheer unpredictability of Mother Nature means there is no room for complacency and every tsunami warning should be taken very seriously.