The 22nd

This time of year creeps up on me. One moment I’m enjoying the hot, dry days of summer, the next it’s triggering memories and disturbing thoughts. In early February 2011, my aunt and uncle arrived from the US, and so those weeks before the quake were a family time. The day my aunt and uncle arrived, my mother, my husband and I took them into the city. We parked on Cambridge Terrace by the PGC Building that wouldn’t be standing at the end of that month and walked along the river to Victoria Square. It was natural to talk about The Quake, they were curious. The city was quiet that day, there weren’t many people around. I remember the hot, dry emptiness of Victoria Square and thinking about The Quake that could have been so much worse.

We spent the weekend before the quake in Murchison. My uncle, who spent his life in Texas and Arizona, couldn’t understand how it could be so hot in the mountains. That weekend coincided with the local A&P show. We ate venison, watched sheep shearing and fed the eels in a nearby creek.

All those memories. And then the bad ones.

The 22nd of February. That day, my mum, auntie and uncle did the tourist thing, going around the city together. I was working.

Where I still live (and work) is north of the epicentre of the February quake, and between September 2010 and February 2011, I became used to the regular rumbles, the house shaking, those small quakes passing through. The morning of the 22nd, there was a little jink at around 9.30 or 10 o’clock. Background noise. Soon after, I received a text message from my mother: they were going to do the cathedral, then have lunch. I’d meet them later in the city.

By 12.30, I had managed to get a big chunk of work out of the way. I’d had a shower and lunch and settled back at my desk for another couple of hours before going into the city. The quake started quickly and was more violent than any quake I had experienced before. I had no time to do anything except be afraid. When the worst of the shaking eased, I thought about the city and where my family might be. All those months of thinking how lucky Christchurch had been with the 7.1 were replaced with the horror over what was likely happening in the city. Mum had said they were going into the cathedral, a vulnerable stone building. They could be dead, I might never see them again. I started to shake and cry while at the same time trying to get past the debris between my office and my cellphone charging in the adjacent room. My phone rang. I just managed to get to it and have a few words with my husband, who worked out by the airport. We were both okay, he would come home, but it might take a while. I was going into the city, I said, to get Mum and my aunt and uncle. Later he said he thought of trying to talk me out of it but could tell from my voice that that wasn’t going to happen.

Just after 1pm, I received a scrambled text message from Mum. Enough to know she was alive and ok, enough for me to head in to the city and pick them up. I was lucky. I heard quickly. Some waited the rest of the day, and far too many never heard back at all.

I left my car in Moorhouse Ave, there was just too much traffic to try and drive in to the city. I walked in to the city and found them just after 3 o’clock in the Botanic Gardens. I’ve never seen these people who loomed so large in my life look so small and frail. We walked back out to Moorhouse Ave, crossing the river at the Antigua boatsheds, the water roiling with the silt stirred up by the liquefaction process. We quickly reached the car and finally reached home over an hour after that, following what would normally be a ten minute drive up Brougham Street. After my husband arrived home, we packed up the cars and left the city, staying at a cousin’s house north of the Waimak for the next couple of nights.

I’ve never been as terrified as I was that day, not just of the force of the quake but at the thought I might have lost the people I love. The memory of that day is sharp for me, but I’ve been able to move on, my family were okay. But there are 185 families that will never be the same again, and it’s them I think of every February, as the weather heats up and dries out, reminding me of those hot summer blue-sky days before the world changed for them.

Low cloud, not smoke

The communications tower on Sugarloaf on Wednesday afternoon as the Port Hills fire was picking up once again

From the lounge window, I can see the communications tower on Sugarloaf, and for the last three mornings, I’ve woken before daylight and checked to see what it’s like over there. Wednesday and Thursday mornings, I could see the tower’s warning lights through a smoky haze. This morning, I couldn’t see it at all, but it’s low cloud, not smoke, obscuring the view.

Outside at 5 am, it was drizzling. What little rain there has been has helped, it seems, although there’s a lot of hard work ahead. Once the fire is no longer a threat, people still have to go through the process of getting back into their homes, one which could be long and draining for those who’ve lost their houses. Many of these people have probably already been through the disaster recovery process and have had their houses repaired or rebuilt following the quakes. To have to do it all over again must be truly heart-breaking.

Fires aren’t covered by EQC, unless they’re a consequence of a natural disaster, so affected residents will be calling upon their private insurers. And because fires tends to be small-scale, localised events, insurers’ exposure to these events won’t pose the same threat to their profit-margin as larger events like earthquakes. Here in Christchurch, insurers have learned some bad habits (and here and here) in the last few years, and it remains to be seen how well they’ll behave with Port Hills homeowners. But the total destruction that fire brings means Port Hills residents likely won’t have to face the repair-anything mentality that has so plagued the rebuild.

Here’s hoping this thing doesn’t spread again, and that people can get back to their homes without another manmade disaster like the one that followed Christchurch’s last natural one.

How to tell ghost quakes from real ones

Back in the days of the Canterbury earthquake sequence, Cantabrians had to wait up to half an hour to learn the magnitude of a quake. These days, GeoNet Rapid tells us within a couple of minutes, or at least gives us a good estimate. But this rapid report can occasionally produce ghost quakes, alerts for quakes that didn’t really happen. So in the immediate aftermath of a quake report, how do you tell a real quake from a ghost quake?

Drums.

Geonet has a network of seismographs that keeps track of what’s going on seismically in our shaky little country. You can get a rough idea of where a quake is located by looking at the snapshot of the whole seismograph network. This the snapshot for the morning of 4 September 2010, 80 minutes after the quake that started it all for us here in Christchurch:

If you look closely, you can see that the Canterbury seismographs show the quake before the others throughout the country.

More recently (this morning), a 5.2 quake near Culverden resulted in a ghost quake measuring 6.3 near Opotiki:

Immediately after the Opotiki quake alert, the seismograph snapshot looked like this:

There’s just a single line for a single large quake sending seismic waves up and down the country. Again, the leading edge of the curve is centred on South Island sensors. That’s the first hint that the other quake reported might be a ghost quake.

For the second hint, we look at the individual seismographs. The seismograph nearest a quake picks it up before those far away, and the one that is near a quake shows it differently than a drum further away does. The trace on a seismograph for a nearby quake tends to be a bit cleaner than one from faraway. Nearby sensors may show part of the event as a red rectangle. This is where the sensor is indicating full scale deflection of the measurement at the displayed sensitivity range – the needle is literally off the chart. Although in this case there isn’t a literal needle, as these are electronic sensors.

This is the 5.2 quake that occurred near Culverden this morning (12th of February 2017), shown on the nearest drum:

 

Now here’s the trace from a drum a fair bit further away, and much closer to the supposed 6.3 Opotiki quake, the Urewera drum near the Bay of Plenty:

A bit messier, yeah? This is the Culverden quake we see on the Urewera trace shown above, even though the Urewera sensor is over 600 km away. There’s no big local quake showing up on the Urewera trace (although there might be a small 3.2 that occurred around the same time as the Culverden one that could be partly the reason the ghost quake got spawned; at time of writing, that’s not yet clear).

Drums on GeoNet are updated every five minutes, so looking at these drums is a good way of quickly determining whether a quake is a real one or a ghost one. Of course, once the duty officer has a look at the data, the information on the quake will be updated and its size and location will be revised. You can see this process by looking at the event summary for individual quakes. This is for a quake that was picked up by the automated system, analysed and revised by that system and then checked by the duty officer:

 

At 1 minute and 49 seconds, the GeoNet Rapid system published an initial magnitude and location when the data was received from the equipment closest to the location. Over the next ten minutes, the automated system continued to update magnitude and location as more information was received from more distant sensors. Then, at 12 minutes and 31 seconds after the quake, the duty officer posted their review of the information the system gathered.

This is what those statuses mean:

Equipment further from the location picks up the seismic waves as they travel away from the epicentre. The sensors are sharing their data and the system matches movements at each sensor to identify which are ‘the same’ quake, which will slow up slightly later and smaller on a more distant sensor when compared to one closer to the epicentre. This automatic matching is not perfect. If the system mismatches a quake with a smaller, later shake on another sensor, it might extrapolate that into a larger quake in the opposite direction, and a ghost quake is born. Once reviewed by the duty seismologist, these quakes are removed from the actual quakes list.

See this story of a ghost quake that showed up in Central Otago after a quake west of the Macquarie Islands.

See Dilemma of deep, distant earthquakes for more information about why ghost quakes occur.

See GeoNet Rapid is here! for a good overview of how GeoNet Rapid works.

Creative synergies

Bleak City Cover
Bleak City cover

The painting on the cover of Bleak City is called Cashel Street, and its by local artist Liam Dangerfield. It shows the Bridge of Remembrance on the Avon River, which lies at the end of Christchurch’s main shopping drag, Cashel Mall. The first time I saw the painting was the opening night of Liam’s first solo show in April 2016, while I was in the middle of writing the last half of Bleak City. The works in his show were all about Christchurch, the ruins of its buildings and its changing cityscape.

My husband and I were both overwhelmed by the multiple meanings we saw in Liam’s works. I couldn’t make up my mind over which one I liked best and kept bouncing between ones that kept prompting memories from my thirty years living in Christchurch. But my husband kept going back to Cashel Street. We purchased the painting and hung it in our lounge, and during the revision stage, I kept coming back to it, asking myself why it had such strong appeal. I folded the answers to that question back into the story. Liam’s art fed the revision process.

The heart of the reason I started writing Bleak City was because of the incredible sadness I felt over what had happened to the people of Christchurch in the quakes and following. People died and that, first and foremost, should never be forgotten. The people who loved them have been changed, and that there has been no justice for those deaths that resulted because of bureaucratic error and neglect says something unpleasant about how our little country at the bottom of the Pacific works. Tens of thousands more have been changed by the insurance process. Many of these people are the walking dead.

I am not a reader of horror or supernatural fiction and related TV shows don’t appeal to me, but yes, I do know there is a TV show called The Walking Dead. My disinterest in that particular stream of fiction is that I find far more terrifying what people actually do to one another, and by that I don’t mean the criminal predators who are the fodder for other fiction genres. Who needs monsters when profit-driven, uncaring, inept bureaucracies are perfectly capable of killing people and destroying their lives?

The man-made disaster

Bleak City is the story of a family living through the Canterbury earthquakes. The main character is Alice Moorhouse, who is 18 and most of the way through her first year at university when the quakes disrupt her life.

The Canterbury earthquake sequence is at the heart of Bleak City. There wasn’t just one quake, the 7.1 quake on the 4th of September 2010 triggered a years-long series of aftershocks, including three magnitude 6+ quakes that were closer to the city than the 7.1. The shallow, violent 6.3 on the 22nd of February 2011 was centred under the hills south of the city. This quake left the city devastated, killed 185 people and injured thousands. Tens of thousands embarked on a long, painful journey to recovery, which continues today.

The novel’s title is Bleak City not to paint a bleak future for Christchurch, but to recognise that post-quake life is a struggle for many people. It was this post-quake struggle rather than the earthquakes themselves that prompted me to write fictionalised accounts of the stories I saw taking place around me. The slow, painful progress of the rebuild and the bureaucratic hurdles people are forced to navigate are having a toll on the city. This is the manmade disaster. The stories of people living in, especially, the south and east of the city contrast with those being told by authorities, who spin the recovery as nearly done, almost there. It’s not, and it won’t be for many years. Some people will never recover, emotionally or financially, and some have died while waiting for their homes to be repaired or rebuilt.