Steep hillsides + loose soil + earthquakes + torrential rain = slips.
Slips (aka landslides) are very common in New Zealand. Roads and houses are built alongside or on top of steep, hilly terrain of soft rock which over time becomes weakened by regular earthquakes and then further destabilised by lengthy periods of heavy rain. This results in hundreds of slips each year.
And they cause huge problems.
Over the past seven weeks there have been 670 slips in the Wellington area with 170 of them coming down on last Thursday and Sunday alone.
Last Friday (just 4 days after my walk along the Escarpment Track) part of the escarpment fell away on to the train tracks and both sides of State Highway 59. This major road is now closed between Pukerua Bay and Paekākāriki for an undetermined length of time while they shovel the rocks and mud off the road and carry out a geological assessment of the hillside. Word on the street is that it is still highly unstable.
The Escarpment Track is also closed, apparently until the end of September while some smaller slips are cleared. When I was up there last Monday, I did see that parts of the path were blocked with piles of dirt and rocks and of course they just happened to be on the narrow bits of the track high up on the ridge where there were no handrails and barriers. I had to carefully step over (and, in one buttock-clenching moment, on to) the piles of loose soil all the while praying that the rocks in the escarpment face on my right that I was grasping hold of for balance wouldn’t give way and send me mud-surfing down to train tracks. Given what has just happened, I might have been closer to disaster than I realised…..
Obviously, slips can cause destruction to property and (less frequently, thank goodness) even loss of life. But they also cause a huge amount of disruption to travel. To explain how the slip on State Highway 59 is affecting people living either side of it, I’m going to need to show you a map and a couple of photos.
Bear with me.
The map below is an old map and shows State Highway 59 (marked with its old name of State Highway 1) that runs along the coast. The position of Transmission Gully is marked with an orange line. At the moment, if we want to go to Paekākāriki or anywhere north of Paekākāriki we have to travel south to Pāuatahanui and then get on Transmission Gully before heading north. And if the residents of Paekākāriki (or any place north of Paekākāriki) want to travel to Pukerua Bay, they have to get on Transmission Gully travel all the way down to Pāuatahanui and then up.
Now bear in mind that Transmission Gully only opened in March this year. So before then, if there was a slip on the coastline road between Pukerua Bay and Paekākāriki, residents of either village would have to take the Paekākāriki Hill Road which sits above State Highway 59. But as you can probably guess from looking at the photo below, this road is also slip prone and is often closed at the same time as the highway below if there has been heavy rain.
The only other route from north to south (or vice versa) is a significant diversion that takes you all the way down to the Hutt Valley where you can get on the Akatarawa Road which leads into Waikanae. But guess what……
Yup. This is one super slip-prone road too. I’ve driven on it and it’s a narrow, steep, twisty nightmare. There is no way on earth you would get me on it after heavy rain. No. Flipping. Way.
There are slips all around Pukerua Bay which given its location perched high up on the coast isn’t all that surprising.
I went out walking down to the beach in Pukerua Bay last Sunday and came across the first slip only a few hundred metres from my house.
Taking the steep beach access path at the bottom of Beach Road which leads down to Ocean Parade, I then came across some precariously balanced pine tree branches just waiting for the right moment to slide on down across the path.
Not wanting to end up buried in a pile of dirt and tree limbs, I moved swiftly past and headed on down to Ocean Parade and started to follow it along the coastline. I had slips on the brain that day and stopped to take photos of the houses perched on the top of the hillside. I had once thought that this location would be an idyllic place to live because of the incredible vista but now they just looked like a massive insurance risk.
Eventually I came to another switchback path that I knew led back up to the road. I was perhaps only 10 metres or so from the top when I came across yet another slip, blocking the entire path.
I guess I could have scrambled over the top of it but it was pretty wet and actually a lot steeper than the photo makes it look. I knew what would happen. I would try to scale it with all the confidence and ability of one of those doomed contestants from Wipeout, frantically scrabbling around for a foothold in the slippery soil while caking my hands, knees and possibly my face in dirt. When I reached the top, panting and swearing under my breath, I would inevitably come face to face with someone walking in down the path in opposite direction who would stop, take one look at me and then back slowly up the path.
Nope. Although I have no doubt that I will be given the moniker of ‘strange English lady’ at some point by my fellow Pukerua Bay residents, I’d rather it wasn’t because someone caught sight of me emerging from a trail looking like I’d been trying to polish a pig.
So back down I went. Back along Ocean Parade and back up the other beach access path with no further obstacles to navigate.
If you want to see a slip in motion, so to speak, have a look at this video of a slip that happened in Nelson (top of the South Island) last Thursday. Although landslides can thunder down at terrifying speed, others are incredibly slow as is the one in the video. But you shouldn’t be fooled by the lack of speed. Once they start, nothing will stop them.