Bay of Plenty Civil Defence officials say they successfully evacuated 78,000 people from the Bay's tsunami-threatened coast in Wednesday's operation Tangaroa exercise.

Warwick Murray with the ‘inundation map'.

The exercise involved a theoretical 3-5m tsunami generated in Chile in the early morning and expected to make landfall in the evening.

On paper the tsunami would have flooded the coast right to the yellow limits of the recently released inundation map, says Bay of Plenty Civil Defence Emergency Management Group controller Warwick Murray.

'The purpose of the exercise was we were really testing our systems, were they up to it, were we able to cope and get a handle on the situation – to quickly identify critical issues, make a decision and get it done. They came through reasonably well.

'It was a significant improvement on operation Ruamoko which we did a couple of years ago. That was based on a volcanic eruption in Auckland and we had to receive a lot of refugees.”

He says the performance was also an improvement on the two real tsunami events, but there is still work to do.

The exercise started at 5.30am, giving the Civil Defence management group just under 14 hours to arrange a coastal evacuation of 78,000 people before the tsunami's expected arrival at the Mount at 7.27pm.

'How you manage that, where you put them when you get them out, and what you do with them,” was the task, says Warwick.

'A lot of them would have been able to go back to their homes, but with a tsunami of that magnitude we are going to lose some buildings.”

The Civil Defence staff was also thrown a few curve balls to keep things interesting – like the 'fatal accident” that closed the Domain Road/SH2 intersection for more than an hour, forcing diversions.

In all, there were about 70 people involved, two shifts involving 20 people at group level. The Western Bay ran three shifts with more than 50 people involved.