Whanganui escaped the severe damage seen around the country following Monday morning’s 7.5 magnitude earthquake which was centred in North Canterbury, and the series of aftershocks that have followed.
But we may not always be so lucky.
The Four Five Hundred had some questions for Whanganui District Council senior emergency management officer Tim Crowe about the city’s earthquake risk and how to be prepared and stay safe in the event of a bigger one.
How did Whanganui pull through after Monday’s quake?
I think we were pretty lucky it was quite a distance away from us. It was a profoundly large earthquake and if it was closer we would’ve been a lot more affected.
It would’ve affected our building stock and other areas quite significantly.
I talked to people around Wellington who had trouble standing up during the earthquake and if we’d had that here we would’ve had a lot more damage.
We’ve had a few bits and pieces. Little bits of concrete have fallen off one or two things but nothing terribly structural, which is good.
Are you able to give us a brief assessment of the earthquake risk in Whanganui?
We have a history of earthquakes. We’ve had a number of earthquakes in the past, since European settlement, quite severe ones. It has caused liquefaction here.
Putiki Church for example has been destroyed in the past by earthquakes and there were some similarities to Christchurch, although they were a bit bigger of course. In the 1900s we had two or three large earthquakes. Taupo Quay for example is believed to have been raised up a metre by one of those quakes.
But the majority of earthquakes felt here historically have come from more distant sources. Eketahuna, Pahiatua are the main fault lines but as you can see now with an exponentially big earthquake we certainly get affected here even though we’re reasonably far away from it.
There are smaller fault lines we are aware of. The Upokongaro fault, Maxwell has a fault and there are faults over in Marton as well. There are few places in New Zealand that aren’t within reasonable access, I suppose, to a fault line. We are the Shaky Isles for a reason.
The Springvale area there used to be, of course, a big swamp which was actually drained by an earthquake.
We have earthquake prone areas that are fairly well mapped out. It is the type of sand and water that… if it’s got a high water table and you shake it, the water escapes and you’ll get that liquefaction effect.
And the other thing is the tsunami risk. In the event of a big earthquake people are told to get to higher ground. Where is higher ground in Whanganui? Where is safe enough?
Yes, we were watching that pretty closely. It depends where you live. We’ve done some pretty comprehensive tsunami mapping – there should be signs going up this week.
The risk areas are close to the river and of course the bottom end of Castlecliff and that beach area there.
High ground, if you’re over by the airport, obviously, you go up hill.
Inland, if you’re heading up Mosston Rd you’re doing pretty well. And same for the top end of Castlecliff, even into Gonville.
You don’t actually have to go far to get to higher ground here. It may look flat, but places like Gonville for example are out of the tsunami risk. The advantage we do have is that Whanganui by where we are has one of the lower risks, even though the whole country has tsunami risk, we’re far better off that most of the rest of the country.
We will direct people, in the event of a tsunami heading our way, to centres that have radio with direct communication to us. So, that’ll be places like Faith City Church, Tawhero School and there’s a number of other ones.
In the event of the big one what do people need think about? Safety, obviously, but once it’s over?
We have an agreement with Brian FM, 91.2, and I was using that on the early hours of Monday morning. Every half hour, on the half hour, we were just updating people who had no other means of knowing what was going on.
That means people who are listening in can get an idea of what’s going on straight from us.
Then if you’re on the coast and there’s a big earthquake like that, there’s no harm in just being on the safe side and moving to higher ground. The natural signs are the most important ones if there’s a nearby earthquake.
Ones you can’t stand up in or if it lasts for more than a minute or if the sea withdraws – those are natural signs that tell you to head to higher ground.
The tsunami sirens we have rely on battery power and the ability of us to generate and set them off which we’ll do if we get a warning from the national command centre.
Check on your neighbours, make sure they’re safe. Hopefully you’ve prepared and you’ve got everything lined up at home. At least three days’ worth of food and water – that’s the key because that reduces the amount of people who need help and allows us to focus on those people who can’t help themselves.
Talk us through how the official response worked in Whanganui?
Once the initial shock settles down I go to work, as do the other emergency management officers and policy people and the infrastructure guys.
On the way in I passed a couple of police officers who had just driven around the Taupo Quay area quickly looking for damage and so they gave a quick ten seconds of ‘no buildings down, no obvious damage’. That was initial information probably about 12.20am.
And then for us it’s gathering information and finding out what we need to do when it comes to our priorities which is of course preservation of life. Then when started working down to the building supply, is there ongoing risk? What do we need to deal with?
We actually had people out doing that, actually physically looking with torches.
The infrastructure team are here at council. They had people out dealing with important things like the water supply, pumping systems, the sewerage system. They become critically important from a whole city perspective. Infrastructure worked through the night on those along with the Powerco guys.
Once the sun came out they went out and did a much more thorough check on the buildings – inside and outside – all through the council infrastructure, the critical stuff that you need to eat, breath, live.