More Flooding! Would You Like a Tsunami With That?


Many ratepayers received notice from Tauranga City Council four months ago that their properties had changed and were now considered more likely to suffer the consequences of a once in 100-year rainfall event.

This set off a trail of diminished valuations, insurance policy exclusions and concern. What is more concerning to me is the content of a GNS Science Report to SmartGrowth which suggests that we are relatively immune to the risk of tsunami following local earthquake events, however the consequence of a quake measuring 8.5 at the northern end of the Hikurangi Trench or Southern end of the Kermadec Plate on parts of our community would be severe. GNS state that it is not a matter of if, but when this quake will occur.

For comparison purposes, the Kermadec Islands have suffered quakes of magnitude 7.8, 7.6, 7.5, 7.6 and 7.6 in the last 60 years.

In the 19th Century Fiordland, Wairarapa and Wellington suffered quakes of 8.0, 8.2 and 8.2. The recent quakes in Christchurch and Kaikoura were 7.8. The travel time for a tsunami from this quake region to the BOP would be short. Tables and maps in GNS’s 100 + page report confirm that Mount Maunganui, Omanu, and Papamoa would be relatively safe, however a tidal wave 6 metres high would come ashore and cover Papamoa East draining back out toward the sea further to the east, with a water depth of up to 5 metres.

This report provides a Table (A5.5.1) which sets out the expected number of deaths if this quake should occur during night time. It reads: DEATHS: Papamoa – 1,260; Wairakei – 400; Te Tumu – 570; TOTAL – 2,230 Under the ‘Official Information Act’, I requested from Tauranga City Council information relating to the tsunami risk for Papamoa, Wairakei and Te Tumu which justifies its decision to provide some 15,000 new residential dwelling sites in these areas over the next 30 years.

Amongst the material received is a SmartGrowth slide stating that the Resource Management Act does not require events of an expected frequency of less than 100 years to be considered, and so Tauranga City Council has set aside any concern from the risk of tsunami on these areas.

Are these people serious?

Later reports on this subject have been provided by GNS Science for other local areas, and I am continuing to research this issue.

I find what I have read to this point sufficiently disturbing to share it with others.

By Peter McArthur – “I write for Bay Waka in an attempt to bring significant community issues to the communities’ notice.”