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14/04/2017, 12 noon.
What we learned this month
First and foremost, I’d like to acknowledge the huge amount of science understanding gained and shared. This is highlighted by the papers led by Ian Hamling, published in Science last month and Anna Kaiser, which is about to be published. These papers confirm what we know: the earthquake that rolled through Culverden, Waiau, Mt Lyford, Kaikoura, Ward and Seddon was more complex than we could appreciate early on in the response. That earthquake moved the South Island six metres closer to the North Island, with 21 faults moving in sequence in some sort bizarre choreograph movement, like a chorus line of dancers. Together they shaped and moved the South Island in ways we didn’t think were possible, but the impossible seems to apply to New Zealand regularly.
I reflect back on the paper I led after the M7.1 Darfield Earthquake back in 2010; I thought we were fast at publishing, and that we knew a lot, but our effort back then was a pale shadow compared to what Ian and Anna and their co-authors have produced and published in five months. The use of InSAR (information from the satellites) is changing the face of geophysics rapidly. Ian and his team are at the forefront of that movement, sifting with amazing speed through the avalanche of data, and Anna and her team were close behind with a raft of techniques.
Speaking of awe, I’d also like to acknowledge Laura Wallace’s contribution of finding the South Island’s first ever recorded slow-slip event that was triggered by the M7.8 Kaikoura Earthquake. It took us some time to determine exactly what happened, and some extra fieldwork to supplement data provided by our network. Land Information New Zealand (LINZ) has been providing us with funding for years to develop and sustain part of our GPS network, along with EQC. Because of this valuable network, we can keep on top of the slow-slip activity throughout New Zealand. Thanks LINZ and EQC! And, speaking of government support, another big thanks to the Ministry of Business, Innovation, and Employment, for helping us fund a large part of the science response to the Kaikoura earthquake.
We can confirm there were huge land movements and shaking near Waiau, among the strongest ever recorded – more than twice the force of gravity. Compare that to passengers taking off in a plane who experience about 10% of gravity, while roller-coaster riders get 1g. The people of Waiau held on through shaking of a strength and violence I don’t like to imagine.
And then there are the landslides. I feel like I need a whole other message just to address our landslide team. Our landslide team have mapped over 5,000 landslides so far due to the earthquakes. Ex Tropical Cyclone Debbie complicated matters greatly, triggering further slips and slides throughout the country. Our beautiful mountains, newly (geologically speaking) arising from the seafloor, haven’t had much time to erode, making them very vulnerable to landslides. So our landslide team is run off their feet at the moment with the combination of earthquakes plus terrible weather.
Naming the Kaikoura Earthquake
Thinking about the shaking in Waiau, there have been some issues raised about naming the earthquake the M7.8 Kaikoura earthquake. After all, the epicentre was closer to Waiau than Kaikoura. And Waiau experienced much stronger shaking, although we did not know that at the time. I will say that naming an earthquake is always a pretty difficult task. Some people would rather we never use their town or city’s name for an earthquake, while others feel that by not using their town’s name we are ignoring them.
When considering naming an earthquake, we take into account a number of factors. It was very difficult to name an earthquake like the one that occurred on the 14 November. With so many faults implicated across more than 150 kilometres of land, and a mountain of data, it was hard to know where to start. In this case, we chose to use a town near the mid-point of the action, near the Kererengu fault, one of the earliest surface faults identified. Also, Kaikoura’s shores were battered by a tsunami reaching up to seven metres above sea level, and their shoreline was raised permanently. But we did not intend to ignore other affected townships like Waiau, Culverden, Hanmer Springs, Ward or Seddon and I apologise if anyone feels they were ignored by us. My team and I think about those townships every day and we will continue to work on your behalf to understand this earthquake and its implications better.
A word about the GeoNet team
Small successes are everywhere; I’ve finally convinced ALL my team to take leave! Many worked over the summer holiday period, just too passionate and stuck into their work to take a break. It has not been an easy task to convince them to take a moment to step away from their computers. Indeed, it is the most challenging part of the job, to get the team to look after themselves.
Our GeoNet website will shortly be completely updated (22 May is tentatively our go live date); you can get a sneak peek here: beta.geonet.org.nz. We need your help to make it better, so please give your feedback.
Stepping away briefly from the science, I’d like to acknowledge the teams that keep us running behind the scenes and often don’t get much acknowledgement. During the Kaikoura earthquake, our website took a massive 250 million hits in 24 hours, peaking at 35,000 hits per second. And it held. We never lost connection to our website or our data streams, thanks to the hard work of our Platform and Development teams. We could not be GeoNet without them, so thanks to you!
Looking ahead for the six-month anniversary of Kaikoura, we’ll have some more exciting science stories planned!
Ken Gledhill (with special thanks to my co-writer, Sara McBride, for keeping me on topic and ensuring I make sense!).
I think of the people in Christchurch or in Waiau, Ward, Seddon, Cheviot, Mt. Lyford, Kaikoura and the many small townships affected by the Kaikoura Earthquake and Canterbury aftershock sequence. Earthquakes are deeply interesting to me, as a scientist, but as a human being I’m still overwhelmed with the enormity of their destructive power. Anyway, I’m sure you are reading this for the science-y bits rather than my feelings about earthquakes. There have been almost 13,000 earthquakes as part of the aftershock sequence from the Kaikoura earthquake; a staggering and sobering number.
Dr. Ken Gledhill, Director of GeoNet
So, while some people got a break over the holiday period (and we tried to stop our staff working but…its really difficult to stop people who are so passionate about their work!) it has been non-stop since the ground stopped shaking under our feet three months ago. Since that time, our scientists at GNS Science and indeed, universities and other research institutions throughout the country, have scattered out of their offices and into the field, collecting samples, measuring coastlines, and identifying and mapping landslides. We’ve learned a lot since that fateful early morning on the 14 November and we will continue to learn for years to come.
In the coming months, we are going to be talking a lot more about the evolving scientific understanding of the Kaikoura earthquake as well as improving how GeoNet runs. So today, I’m giving you the heads up about some important projects:
The improved GeoNet website – now available for testing
Lovingly known internally as our Beta website, we’ve actually been working on this behind the scenes pre-Kaikoura earthquake. We had initially planned the launch the week of the 14 November, but with our improved understanding of the needs of Kiwis regarding our geological hazards, we’ve made some modifications.
I know lots of people have been asking about the website for a long time. Some improved features include more technical information for each earthquake as well as the associated news stories. But for those of you who like volcanoes, we’ve got you covered too. I’ll admit though, our landslide and tsunami sections are still a bit anaemic; but this is a work in progress. You can go to the Beta website here.
And we need your help to make the new website better! Please fill in this survey after you have finishing reviewing the website to give us all your important feedback on what’s working for you with the site and what isn’t. And my team wanted to bring back the Volcano Kitten T-Shirt competition. My apologies to good taste everywhere, but I couldn’t stop them. More on that competition soon.
It won’t replace the old website until later in the year but we want to test it out early to get all the bugs out of it we can.
New Zealand’s Science Briefing about Kaikoura – 14 March at 12 noon
One of the really inspiring parts of working on the Kaikoura response during that first few weeks was the science briefings at 9 a.m. every morning. I was privileged to listen to some of the best minds in New Zealand discuss the science of the earthquake. Each and every day, something new was presented that really intrigued me. We are developing this concept of a science briefing for 14 March because I wanted us to be able to share with you what a science briefing is like, live.
So, we will be streaming our science briefing live, to you, via Facebook. We will also record it and pop it on YouTube for those of you who don’t have Facebook. We are pretty excited about being able to bring this to you. In a few days, we’ll be putting an event on FaceBook where you can pop your questions.
Beta Website and the Volcano/Kitten T-Shirt competition
Enhanced Geological Hazard Monitoring
Just before Christmas there was an announcement by the Ministers of Science and Innovation and Civil Defence to help assist us with increasing the nation’s capacity for geological hazard monitoring. We are working hard behind the scenes with key stakeholders to see how we can better deliver for all of New Zealanders. More in this space in the coming months.
These are just a few of the major projects we are working on at GeoNet.
Love for our Duty Teams
I just want to finish by giving a bit of love (following the Valentine’s Day theme) to one of the hardest working teams at GeoNet – our duty teams. GNS Science provides GeoNet with some of the top minds in the world to help us inform New Zealand on urgent geological hazard news. These teams work under the most stressful conditions, putting their own research interests aside for the benefit of the entire country. These teams work throughout the year, on top of their other jobs (many are world leading seismology, volcanology, engineering geology and other types of researchers).
When you are trained as a scientist, there is no class you can take that teaches you how to make split second, complex decisions on very little data, knowing that your decisions can impact many people. It is a heavy load to bear for our scientists and I thank them from the bottom of my geophysicist heart for their absolute dedication to this difficult role. I have been there – I know how hard it is! GeoNet could not run without these vital teams. Thank you.
Thank you everyone for a great start to 2017 for GeoNet. I look forward to us all continuing to roll up our sleeves and getting on with it in the coming year. I wish you a wonderful Valentine’s Day and a quiet Earth!
Let’s start with “this year in earthquakes” in New Zealand...
Earthquakes: a record-breaking year
This year had many earthquakes, but we are going to focus on the main two magnitude 7.0+ quakes that affected numerous communities: shaking our capital, Wellington, our weary quake-familiar Christchurch. Even our biggest city, Auckland, felt the sway of the East Cape earthquake. You’d be hard pressed to find someone who wasn’t impacted, in some way, by earthquakes in New Zealand this year.
By the numbers, our monitoring network recorded 32,828 earthquakes this year. To give a point of reference, on average we record about 20,000 per year. Our other active year reached 29,000 in 2011. 2016 wins the dubious honour of most earthquakes ever recorded on the GeoNet network (we’ve been around for 15 years). This year we had 122 earthquakes between magnitude 5.0 and 6.0,10 magnitude 6.0-6.9s, and, two magnitude 7.0 plus earthquakes. It’s been a geologically busy year. So let’s get into the earthquakes and their aftershock sequences that were the main contributors.
On the 2nd of September at 4.37 am, an M.7.1 earthquake struck 22 kilometres deep off the northeast coast of New Zealand. Luckily, the damage was minimal on land, although a small tsunami was generated. A strong aftershock sequence continued in the days following. Now, in any other year, the M7.1 would have been the biggest earthquake in New Zealand. But, New Zealand was just getting warmed up.
A little over two months later, at 12.02 a.m., the ground shaking began in North Canterbury, starting near Culverden. In two-and-a-half minutes, the earthquake moved across numerous faults, its seismic energy pooling and then overflowing onto one fault after the other, moving similar to the famous “Bucket Fountain” in Wellington. Along the way, the earthquake ruptured faults, tore through the earth and raised the seabed off Kaikoura. From Christchurch to Wellington to Nelson, the whole part of the upper South Island and Lower North Island were impacted. Thousands of aftershocks have followed since the ground first shook. There is some pretty amazing video, taken by our Julian Thomson and starring Kelvin Berryman. Thanks, Julian and Kelvin!
The M.7.8 Kaikoura earthquake will not go into the global history book of earthquakes because of its magnitude; the Ring of Fire regularly gets that size and much larger earthquakes. What makes it unique is two things: how it ruptured across the faults through the North Canterbury and Marlborough Fault areas and the slow-slip earthquakes triggered by M7.8. While we knew the faults were all there, we had only rarely seen an earthquake behave quite like this one.
Secondly, the slow-slip events or “silent earthquakes” started right after the M7.8 Kaikoura earthquake stopped. Our understanding of slow-slip earthquakes is evolving due to its relatively recent detection in 2002 in New Zealand. We don’t yet fully understand what it means to have slow-slip events triggered by the M.7.8. However, we are cautious as to what this might mean for future earthquakes. We’ve included these events in our probabilities and scenarios for this aftershock sequence. These two unique factors make this an earthquake of significance; New Zealand breaks new ground again!
It can be easy to get carried away by the excitement of the science of the earthquakes. However, the impact of these earthquakes is real and can be very painful for those who experienced it. Earthquakes, especially the large ones like East Cape and Kaikoura, can be anxiety producing; this is normal. Everyone responds to earthquakes differently, so if you are feeling unusually high anxiety due to the earthquakes, there are people here to help you through this time. If you are anxious about the earthquakes and this is affecting your ability to go about your daily life the All Right? Hotline (0800-777-846) is a great resource where you can talk about any anxieties or concerns that you have regarding the earthquakes. Remember to also seek support with friends and family, and to take time out to do things you enjoy.
Tsunamis: the rehearsal and the real thing
This year, we were part of a national Ministry of Civil Defence and Emergency Management-led exercise regarding tsunami called Exercise Tangaroa. This exercise involved the whole nation’s civil defence groups and many other agencies across the country (link). Two days later, at 4 am, we had a striking coincidence with the M7.1 East Cape earthquake, which generated a small tsunami (30 cm). The residents near the East Cape earthquake did the right thing by evacuating immediately to higher ground.
Again, those who evacuated immediately on feeling the long and strong earthquake did the right thing.
If you are on the coast and you feel an earthquake that is long or strong, get gone.
2016 in Volcano Land
We asked our favourite volcanologist at large, Brad Scott, to give us the words for his thoughts on volcanoes in 2016. Here’s the lowdown from Brad:
2016 saw a variety of activity from our active volcanoes, ranging from violent explosive activity to small-scale geysering and a mystery submarine eruption, creating a random pumice raft near Tonga. Also included was volcanic unrest, a hydrothermal eruption and remobilisation of old eruption deposits.
High-intensity rain in January saw debris (sand, clay and rock) left over from the 2012 Te Maari eruptions remobilised by the heavy local rainfall and washed out of the valley below the vents.
Then, it was White Island (Whakaari)’s time. On Wednesday 27 April, a moderate steam and gas-driven eruption occurred at White Island (Whakaari). The eruption ejected the Crater Lake, created a new sub-crater, generated landslides/collapse and excavated some 13 m of the Crater Lake floor. This generated a very energetic blast that covered much of the Main Crater floor and the north-eastern portion of the volcano with some quite festively coloured green tinged ash. This eruption occurred during a period of volcanic unrest. However, we were challenged initially to confirm it had happened. These steam and gas driven eruptions do not give any useful warning.
Mt. Ruapehu’s Crater Lake heated up, cooled back down and then promptly heated up again and then back down again. White Island had another hydrothermal eruption in September and then went back to simmering. Finally, we saw some pretty dramatic geyesing in Rotorua in the lake. The geysers had been pretty quiet for 15 years but decided this was the year to reawaken.
Landslides: slips, slides and the smothering of State Highway One
The newest member of our public information team, Helen Jack, wrote up her thoughts on landslides. Helen is a landslide enthusiast, although she has a fond place in her heart for glaciers as well. She works out of our Dunedin office.
Landslides triggered by earthquakes took the (rather large) cake in 2016. The M5.7 Valentine’s Day earthquake in February rattled down more rocks and cliffs along the eastern Port Hills in Christchurch.
Then, just as our landslides scientists were wrapping up almost six years of work shaken onto their plate by the Christchurch earthquake, the magnitude 7.8 Kaikoura earthquake delivered up an even bigger serving. The earthquake caused over 80,000 landslides throughout North Canterbury, Kaikoura and Marlborough, damaging farmland, smothering State Highway 1 and the Inland Kaikoura Road in many places and damming several rivers. Heavy rainfall events throughout the year brought down landslides in the usual suspects of Haast Pass, Nelson/Tasman, Wellington and the Rimutakas, the Manawatu Gorge, East Cape and Coromandel. Of course, a New Zealand summer wouldn’t be complete without an ex-tropical cyclone or two: In January Victor brought down landslides from East Cape to Tolaga Bay.
While landslides kept road crews very busy, and some property was damaged this year, we continue to be very fortunate that no lives were lost from landslides in 2016, particularly given the amount of landslides caused by the Kaikoura earthquake.
GeoNet turns 15
GeoNet also turned 15 years this year. In 2001, we started as New Zealand’s first national seismological monitoring system. In those 15 years, we’ve grown from a small fledgling network with a handful of online sites to more than 650 monitoring stations around the country, as far north as the Kermadecs and as far south as Antarctica. You can read more about our 15 years of monitoring New Zealand’s geological hazards here.
(Caption: Sara Page, our public information specialist for social media, put the newsletter together detailing all the geological events that GeoNet has monitored in the last 15 years.)
2016: Ground-breaking but New Zealand still unbreakable
It was a challenging year but also inspiring to me about how we all pulled together. So while 2016 was a groundbreaker, it didn’t break us but rather pulled us closer together as a team. This country faced some pretty big challenges, once again, due to seismic forces. And like the devastating events of 2011, people came together and helped out. Volunteers from all over the country came to assist Kaikoura, Ward, Waiau, and other affected communities in North Canterbury, Marlborough and Wellington. It was a terrible year for those communities and people affected by these earthquakes. We support those communities in their ongoing recovery.
For my part, working for GeoNet, I was overwhelmed with the support we received. There were hundreds of “thank you” emails, tweets, and Facebook comments this year from people, which we really appreciate. Further support came from our friends at the Ministry of Civil Defence and Emergency Management, who also work tirelessly this year. We couldn’t have done all the hard work this year without our supporters at EQC, LINZ, DOC, MetService and MBIE.
A couple of brief thank yous are required with a year like this one. Our technical support and services team diligently worked so we didn’t lose service during this challenging time, and our app and software developers helped us provide new and improved services. Our techs worked hard, putting up new temporary sites to better capture every ground movement in North Canterbury and around East Cape. They even found time to innovate with the new ‘Spade-tenna’ (patent pending). We certainly could not have supported GeoNet this year without our team of duty officers. All of these people help support GeoNet. We thank them for their continued service to New Zealand’s geological hazards monitoring network.
2016 was also the year we said goodbye to our manager, Kevin Fenaughty, who had been in charge of public information since the beginning of GeoNet. Kevin left us this year one week before the Kaikoura earthquake for a new job in MCDEM. He sent flowers to say "sorry" but to be honest, we're still a bit grumpy about him leaving. Anyway, if you like our stories, you can thank Kevin because he hired us! So, thank you for your long service, Kev. Also, Natalie Balfour, who was on the public information team for a short but very busy ten months, is now our data management team leader. She did a great job as part of the team but now has another big job in GeoNet. We wish both of them well in their new jobs.
So what will 2017 hold? I’d like to say that 2017 will be more like 2015: mostly harmless. But there are no guarantees; nature is a terrible project manager. Some years it’s almost too much while other years, it’s quiet. One thing we can say is that, at GeoNet, we are taking the lessons learned from 2016 and will continue to improve our network, our website, app, and all our services. We hope for a quiet, calm 2017 but the best thing we can all do is be prepared for whatever happens next.
To find out more here about how to prepare for emergencies, visit our friends at:
After the M7.8 Kaikoura earthquakes, our techs quickly took to the air to put in more temporary sites throughout the Kaikoura Mountains and Southern Alps. The problem with these locations is its remoteness and sustained damaged to cell towers from the earthquake.
Now, when our techs go out into the field, they can only take the most important items with them due to limited space on the helicopters. Our techs are dropped off into the middle of nowhere with few supplies to make these temporary sites. Think “Survivor” but with a radio, some seismographs and a couple of muesli bars. Our techs are able to put in these temporary sites in a matter of hours.
The lack of space has made our techs…become creative in their use of tools. Recently, they realised their antenna needed more height to communicate with base. They cleverly repurposed a spade (used to dig out ground to place the site in) and used electrical tape to put the antenna on the spade. BOOM: instant communication tower. The Spade-tenna© (patent pending) was designed to elevate the antenna in order to increase cellular signal strength in remote locations. This means we don’t lose contact with these sites.
They quickly put up 9 temporary sites since the earthquake stopped shaking, 4 with the clever spade-tenna.
Tim McDougall, one of our techs, said they were proud of their latest innovation but that they are now running out of spades…
A big shout out to our techs because these sites are a critical part of our ongoing monitoring of the M7.8 Kaikoura aftershock sequence. We couldn't be GeoNet without the people looking after our 600 plus monitoring sites throughout New Zealand.
Stress and the earthquakes
Now, I can’t tell you what to feel or how to respond to the earthquakes. But I’ll just share with you what helps me deal with anxiety or nervousness.
1. Understanding the science. Knowing as much as I can about the phenomena comforts me. I try to learn as much as I can.
This leads me to getting to talk about my favourite thing: numbers! Especially measurements (that is data). This earthquake is astounding, with movement along at least 5 separate faults extending around 150 km up the east coast of the South Island with land changes of up to 11 m horizontal and 5 m vertical. Maximum ground shaking of at least 1.3 times the force of gravity at Ward in Marlborough. The tidal gauge that recorded the 2.8 m tsunami at Kaikoura, was uplifted by 90 cm. We recorded the tsunami up to 4 m height at Little Pidgeon Bay. Since the earthquake occurred we have recorded more than 5,500 aftershocks. And these numbers are only a few of the large number of measurements of this earthquake.
And then there are the numbers of regarding the probabilities and further aftershock maps we are publishing. It’s natural to feel anxious about these numbers. Our scientists develop these to understand the potential future. We couldn’t do this even 10 years ago. The ability to have some kind of knowledge about what is possible can help us plan and move forward, as individuals and as a nation.
There is a lot of very good science information going out about this earthquake and not just from GeoNet and GNS Science. The Science Media Centre, QuakeCore, Victoria University of Wellington, NIWA, Massey University, University of Auckland, University of Canterbury, University of Otago, Waikato University, and many others are contributing to the ongoing science response. I want to acknowledge and thank all the scientists working hard around New Zealand right now. It is a great team effort and I’m proud to be a part of it.
Just a quick side comment about the science community and transparency. Anyone can take our data and develop their own models, they don’t have to come to us or other parts of GNS Science. EQC has paid to ensure our data is freely available to anyone who wants it. This means we are completely open about our data. Any praise for GeoNet should also be reflected onto our most steady and supportive funder - EQC, who had the foresight to develop the open data policy at the start of GeoNet in 2001.
So, those are just the quake numbers. Let’s talk about GeoNet numbers. We’ve had 1,300,525 unique visitors to our website and 169,028,688 earthquake notifications have by our app. We thank Fastly, Urban Airship, and AWS for helping us deliver this performance.
2. Prepare, prepare, prepare. What makes me feel more comfortable is being prepared. I know I do feel better if I am prepared. We have emergency supplies (my new house has 10,000 litres of water storage for example). While not everyone can store that much water, there are simple things that everyone can do.
The Ministry of Civil Defence and Emergency Management (MCDEM) are the preparedness experts and we support their message fully. We can’t stop nature from doing its thing and it may not give us notice about what’s going to happen next. BUT we can control how ready we are to respond to nature and bounce back after the event.
During this sequence, we’ve already had two large gales hit central New Zealand. Being prepared comes in handy during storms, floods and all other manner of emergencies too. Please visit www.happens.nz. Our friends at MCDEM (and we are very good friends, having worked so closely together over many years) have put together some great resources on how to be prepared.
Together, let’s make New Zealand the most prepared country on the planet. Let’s be the people who are ready for anything.
3. Focus on the really important things: relationships. I came home for the first time since the earthquake on Saturday evening, and my cat, Poppy, greeted me at the door with very loud meows. Poppy put her furry face in my shoes for a big whiff (I don’t know why she’d find that comforting) and then demanded cuddles for five minutes. Her small, purring presence helped remind me what is important in life: it’s my relationships. Further, the comfort and support I’ve received from my wife and three daughters, as well as my staff, help me keep all this into perspective. I thank them for their unwavering support.
Are earthquakes scary? They certainly can be. I’m not trying to downplay tragedies or anxiety. I encourage us all to consider what we can do about it. We can’t stop the earth from shaking; more earthquakes will come. If not now, someday. New Zealand’s beautiful mountains were created by earthquakes and uplift. Earthquakes are why, in part, our country exists.
Numbers are great but it's still about people
One more word about our staff. They are tired and they have really worked amazingly hard. Like so many other people working for Civil Defence agencies, the Defence Force, the Police, USAR teams, council workers, infrastructure managers…we are all working very hard for New Zealand, and for you. I need to remind them, and myself, that we are working under extreme conditions with the world still moving underneath our feet. They have my thanks and gratitude.
I just want to share one small anecdote before I sign off. Starting in the early hours of Monday 14 November, our field techs quietly got gear ready, booked helicopters, and were out the door to service and install extra sensors so we could get a better understanding of this quake. Our tech ‘ninjas’ quietly did their jobs. They rarely get the spotlight but our techs are champions. Without them, we wouldn’t have GeoNet.
Dr. Ken Gledhill
6pm, Wednesday 16/11/2016
What has changed since our initial review
Based on our findings and in discussion with international researchers, early indications are that this is one of the most complex earthquakes ever recorded on land. This complexity means we have had to take extraordinary efforts to determine the magnitude, depth, and locations.
The very long time it took for the faults to rupture (over one minute) meant that the standard methods of calculating magnitude were insufficient to capture the full energy released.
Due to the size of the quakes, we’ve gathered data from our entire network of seismic stations. All of these stations would not normally need to be included in magnitude estimates.
Further, our techs at GeoNet went out to several sites which we lost communication with and we have now been able to upload this information, so we have a more complete understanding of the ground deformation and strong-motion data.
Finally, our science teams have been working tirelessly, going up and down the affected areas and measuring the length of faults and how much they moved. Their efforts have provided us with a clearer picture as to the size and length of the ruptures.
Based on all these ongoing efforts, we can say with some confidence that the earthquake was an M7.8. This is consistent with estimates from several other international agencies, specifically the USGS. Their early model provided us important information and we used all our additional data sets to confirm the magnitude.
What this means
The new magnitude just tells us what we think most people who felt the earthquake already know: it was powerful, and went on for a long time over a large distance. It doesn’t change what happened but it does provide us with more knowledge about how significant the event was.
Our recent analysis confirms the complexity of this event. It does not change any of the observations of strong ground motion, fault breaks or GPS recorded movement of the earth’s surface – these are physical observations independent of the magnitude of the earthquake.
We are in the process of revising our probabilities and scenarios based on this new information and should have this released within the next 24 hours.
Good science takes time
Our GeoNet seismic network is robust and records tremors and shakes throughout the country. However, with these very rare large events, it requires time and thought as to what all of this new data means. This earthquake required us to take a different approach and we have been triaging the data to reconcile all the different data sets.
8:30pm, 15th November
With the flooding, earthquakes and tsunami, it feels like Central New Zealand is getting a hammering by our most brutal project manager: nature. And nature has been particularly demanding in the last 48 hours and I just want to share a few of my thoughts about what is going on.
Dr. Ken Gledhill, Director of GeoNet
M7.5 Earthquake: a monster in the making
As a geophysicist, there are a few important things to know about this quake and they are already available in various places and forms. It was a monster quake, one that has shocked us all with its intensity and ferocity. Because of its size it made our world shake strongly but relatively slowly for a very long time. It is a complex, brooding beast we are still trying to understand. Although we published information on it very quickly, please forgive us as we tell you more and revise what we have already told you.
Tsunami: those who took action did the right thing
In terms of the tsunami, I said it here in the M7.1 East Cape Earthquake. Because we do not have a 24/7 monitoring centre we have to wake people and get them out of bed to look at complex data and make serious calls very quickly. It is not an ideal situation given the past few months and I’d like to change that by getting support for a 24/7 monitoring centre for geohazards. I’m going to be blatant in my campaigning for this, because I think we need a 24/7 monitoring centre to respond to these kinds of events.
But, even with a 24/7, we may still not have been fast enough for people in Kaikoura. The best advice is still: if you are at the coast, and feel a long or strong earthquake, be gone. For those people who took those brave steps in the middle of the night of the tsunami, I applaud your efforts. YOU DID THE RIGHT THING. For people who were further away and waited but left once told to evacuate, YOU ALSO DID THE RIGHT THING. We were lucky the tsunami struck at low tide; high tide could have left more damage than I feel comfortable thinking about.
Moon and earthquake lights
GeoNet only reports on things we can measure. This is why we stick to our knitting: geophysical data. We know that people are really interested in what we think about the supermoon or earthquake lights, but we just don’t have any way to measure their effects using the GeoNet sensors. So, I am just going to leave that topic for other people to discuss.
Kiwis: we’re a unique type of tough
I just want to say a few words about people. This is a painful time. People have died and we mourn with their family and friends. I can only imagine how people are struggling right now in Kaikoura, Ward, and Waiau and the other affected regions. Also, people in Christchurch are experiencing reminders of an earthquake nightmare they might have thought was over, only to realise that sadly, earthquakes are part of the standard operating procedure here in New Zealand. In the Wellington region, we are now experiencing intense flooding, complicating our ability to recover from this earthquake. This combination of hits from nature is exhausting and upsetting.
Damage from the M 7.5 Kaikoura Earthquake
But here is the upshot. One thing I know about us Kiwis, we are prepared, tough, and able to cope with almost anything. It is perfectly acceptable to be scared by this earthquake but we will get through this by doing what I think Kiwis do best: helping each other. We saw this with the Canterbury earthquakes and we are seeing this again. We are also good at taking care of our visitors and our new Kiwis as well.
I can’t relieve anyone’s anxiety about future earthquakes; more will come. What I can say is that preparedness, that old Civil Defence and Emergency Management mantra, is the best solution to being ready for these events. Please visit our friends at the Ministry of Civil Defence and Emergency Management to find out how you can prepare. To learn more about your tsunami evacuation zones and advice, visit your local and regional council. To learn how to keep your china, house and other precious items safe, visit our friends and funders, EQC.
To our GeoNet staff: a huge thank you
Finally, I just want to say a few words about my staff. I’ve been the director for more than a decade and they have never let me or New Zealand down. Their service to New Zealand, science and people, is phenomenal. They really care about what they do. I thank them for their tireless efforts, keeping GeoNet functioning, sleepless nights locating earthquakes or even sending that late night cheeky Tweet. What makes GeoNet a world class geohazards monitoring system is not our instruments (as much as I love the technology), but our people. When people send kind words via social media or emails or phone calls, my staff feel that support deeply, so thank you.
Dr Ken Gledhill
Director, New Zealand GeoNet
Gisborne and Hawke's Bay slow-slip event follows M7.8 Kaikoura Quake (includes Porangahau information, updated 26/11/2016)
Kaikoura Earthquake 2016: Paptea Fault Rupture (Kelvin Berryman explains it all!)
Rapid field reconnaissance indicates that multiple faults have ruptured:
Kekerengu Fault at the coast - appears to have had up to 10m of slip
- Newly identified fault at Waipapa Bay
- Hope Fault - seaward segment - minor movement
- Hundalee Fault
Other faults have also been identified as being involved in the earthquake. In the simplest case an earthquake is a rupture on a single fault plane.
What we are finding in New Zealand is that quite a few of our larger earthquakes involve jumping from rupture on one plane to another in a complex sequence. We first saw that with the Darfield Sept 2010 EQ where multiple segments ruptured together as a single earthquake. We appear to have seen this again overnight.
In terms of what might happen next: The scenarios provide an overview of how we see this earthquake sequence evolving over the next few days to one month. What is on the web page is our best information that we have to hand at the moment. As our science information flows in over the next few days we expect that information may evolve.
ShakeMap for the M7.8 Kaikoura Earthquake.
A word about the Moon
Some people have raised concerns about a link with the supermoon. In large groups earthquakes exhibit slight associations with lunar cycles, but this is not reliable for forecasting. We have two tides a day throughout New Zealand and at any one place there is no clear association in location. The occurrence of the full moon around the globe does not allow us to say how big, when and where any earthquake might be.
Long term earthquake rates
There were more large earthquakes in a period of several decades prior to about 1950, and it has been relatively quiet since then. Since the M7.8 in July 2009 in Fiordland, that quiet period appears to be over. The reason we had a tsunami generated by an earthquake with an epicentre onshore is that there was deformation further down the fault plane offshore.
Wellington area faults and the subduction interface beneath Wellington are captured in the probability table and the scenarios given there. We do not have any evidence of an impending large earthquake of a similar size in Wellington at this stage but we cannot rule this out. We cannot make a calculation to predict this, but the chance of a further shock in the Wellington area has increased somewhat since the Kaikoura earthquake.
Why were our magnitudes different from the USGS: About magnitude variability
We have changed the New Zealand local magnitude for this earthquake to M7.8.
Felt it? Tell us about it.
Our Felt Detailed report for this earthquake is now available. Please help us by filling out this report to help our long term research programme.
We will be continuing to gather information about this earthquake for some time. We will continue to keep updating information as we learn more about this earthquake.
Be prepared – both physically and mentally
Beyond physical preparedness is the emotional and psychological support for these earthquakes. The All Right? Hotline (0800-777-846) is a great resource where you can talk about any anxieties or concerns that you have regarding the earthquakes.
Map of the aftershocks associated with the M7.8 Kaikoura Earthquake.
MCDEM have issued a tsunami threat for the initial earthquake. Our tide guages at Kaikoura, Wellington, and Castlepoint have recorded this. Please follow advice regarding tsunami via the Civil Defence website - anyone at the coast on the East Coast of New Zealand move to higher ground.
Thus far there have been approximately 45 aftershocks. It is difficult to predict an aftershock sequence because it is too soon after the initial earthquake to understand the pattern. We need more time and aftershocks to occur so we can get a better picture of what is going on.
Scientific information about the quake
Peak ground accelerations (PGAs) have been recorded up to 0.23g in Wellington. This is similar to the 2013 Lake Grassmere and Cook Strait earthquakes. The PGAs closer to the earthquake will be much larger. We are still working on calculating these values.
Our GPS stations record how land moved in response to the earthquake. Our station at Cape Campbell in Malborough moved two metres north.
Updated at 03:25am More information soon.
About Felt Detailed
This new long-form questionnaire is based on the older Felt reports that you might remember from earthquakes past. However, because we only bring it out for (hopefully) rare larger quakes we’re now able to tailor it for specific earthquakes. For today’s survey we’ve included tsunami related questions. These new questions include asking what you did during and after the shaking, how you like to receive information, and whether you were concerned about a tsunami. We use your valuable insights to better estimate the shaking intensity caused by this earthquake and to better understand the effects of future major earthquakes in New Zealand. These new questions allow us to work with social science researchers to help us better understand how people think and act during earthquakes. We’ve also been able to increase its stability by having it hosted by SurveyMonkey.
We chose SurveyMonkey as our provider for the Felt Detailed because we know it works. The social science team at GNS Science has used it to collect thousands of surveys over the years. We think it should be stable and secure enough to handle all the great information that you’ve got to share. Be aware that this is a very new system and we had to forego a part of our user testing to make it live for this earthquake.
If you felt today's big earthquake, give the new Felt Detailed a go and see what you think. That way you would help us both with the early response (through Felt RAPID) and with the research (through Felt Reports: Detailed). Most of the time, you can stick to clicking a button on Felt Rapid.
P.S. We’ve had a lot of feedback from you guys today about the new felt reporting system not working. Sorry. This was the first big test, and it didn’t perform so well. Why did this happen? Our Google assisted address search was capped at 150,000 searches, and we went over this (Google searches every time you type a single letter into the address bar, so it goes through 150,000 searches quickly!)
Go to Felt Detailed.
National Warning: Tsunami Marine and Beach Threat CANCELLED
Issued at 08:30 NZST 02 September 2016
The Ministry of Civil Defence & Emergency Management (MCDEM) has cancelled the tsunami marine and beach threat warning in place for the North Coast Regions of the North Island of New Zealand.
Based on all available data, the greatest tsunami activity has now passed. However, coasts may still experience unusual, strong currents and sea level fluctuations lasting for several more hours.
At 4:37am today a magnitude 7.1 earthquake struck 100km off the coast of East Cape. The tsunami experts panel is active and is assessing the situation with the Ministry of Civil Defence and Emergency Management (MCDEM).
Shaking was felt throughout the North Island, with nearly 5,000 felt reports reported to GeoNet within the first 20 mins of the earthquake. As at 7:10am there have been 57 aftershocks, the largest, is a magnitude 6.2 quake. Aftershocks can be expected to continue for some time. This morning's quake was preceded by a magnitude 5.7 foreshock at 10:04am yesterday which occurred in the same area. (Note: there is no way to tell if an earthquake is a foreshock, only when the larger quake occurs can we call it a foreshock).
This area is no stranger to large earthquakes. In February 1995 there was a magnitude 7.2 earthquake off the coast of East Cape, further to the south than this morning's earthquake.
If you felt this earthquake, we'd like to learn more about your experience. You can now fill in Felt Detailed here. This longer form felt report takes a bit more time than our Felt Rapid system but it provides valuable information to our scientists about the earthquake.
This will be updated as more information comes to hand, last updated at 4.10 pm.
I’ve worked in or around Civil Defence organisations for over a decade and rarely are the words “no duff” spoken in an exercise. "No duff" means that something real is happening and we need to pause the exercise to respond. Our duty officer returns quickly with the news that, while the earthquake was large, it won’t directly affect New Zealand. We get back to the exercise at hand: the national tsunami Exercise Tangaroa.
Working in Civil Defence Emergency Management exercises can be a strange experience for the uninitiated. There are all kinds of specific terms and acronyms used like CIMS (Coordinated Incident Management System), EOC (Emergency Operation Centre), and CDEM (Civil Defence and Emergency Management). There is good reason for all the acronyms; Civil Defence has developed, partially, out of a military heritage from post-World War 2 and the use of these acronyms helps generate a shared understanding as well as being able to work at speed. But Civil Defence has evolved well past its post WW2 roots; it is now a coordinated group of all first response agencies (Police, Fire, Ambulance) combined with Health, welfare agencies (Red Cross, Salvation Army etc…), lifelines (water, electricity, transport and gas providers) and the coordinating agencies; the local, regional (CDEM groups) and national (Ministry of Civil Defence and Emergency Management). The CDEM structure also includes GeoNet and GNS Science, to provide science advice and information to the responding agencies, specifically MCDEM. And, while CDEM focuses its exercises on agencies, everyone is needed to respond effectively, as seen in Christchurch with the Student Army.
Exercise Tangaroa was a scenario of a large tsunami (M9.1) located in the Kermadec Islands, slightly out of the coverage of the GeoNet sensor network (the writers of exercises can be mean sometimes!). As a regional source tsunami, it means we have little time to determine its impacts before the tsunami hits our shores, unlike the distant source tsunami, where CDEM agencies get hours to carefully plan if evacuations are necessary. However, we still have a role to play in bringing together the Tsunami Experts’ Panel, a group of expert volunteers who assist MCDEM in understanding what the possibility of tsunami impacts are after a large earthquake off the New Zealand coastline. Exercises are always pretty stressful affairs, with miscommunication, misdirection, rumours and systems barely holding up under the pressure. But this is the value of exercising; to see where the gaps are so we can better plan for when the real thing happens. It is stressful, even notionally, working to respond to a pretend tsunami that could have such damaging affects to the people of New Zealand.
Needless to say, we were all pretty tired after Exercise Tangaroa. Imagine our unpleasant surprise when our system detected a large earthquake off the coast of Te Araroa this morning. Our seemingly tireless duty officer sprang into action, shaking off any stress from the day before and quickly refined the earthquake's depth and location. Our duty officer provided us with what we needed; more clarity on the location than our automated system provides. After a brief flurry of media phone calls and social media questions, we have a cup of coffee together, take a breath and prepare ourselves for what Mother Nature may have in store for us next.
It is something I’m always being reminded of at GeoNet. Exercising is somewhat reassuring because at least you are aware of when it is coming. In real life, we get no such warning. We don’t know when a damaging tsunami may strike our shores but, if the past is any indicator, we should be as prepared as we can be.
One of our partners, MCDEM (the people who ran Exercise Tangaroa) have put together a great website that can help you prepare for all kinds of emergencies, not just tsunami:
Why is New Zealand so shaky?
What it took to locate earthquakes before GeoNet
Find out what scientists are doing with our earthquake
data and how that impacts New Zealand
GeoNet and EQC's great partnership
At GeoNet we're always trying to improve on our services. We don't have a large team, but we try and stretch what resources we have. So…we've just started a re-design of our website, and we want to make sure we get it right - from the ground up - so it's easy as possible to find the information you want. We'd really love your help in building a better website.
We'd love it if you could complete our online survey - it's mobile friendly too! It has 15 questions, and may take between 10 and 15 minutes. Before we get on to the look and feel of the website, we're starting with the basics - how we structure our webpages. We want to know where you would expect to find information about our various hazards. The survey will be up until midday Monday 29th February.
As a small thank you, one “lucky” survey participant will receive this t-shirt from GeoNet, with our thanks. Yes, it’s an image of a kitten coming out of a volcano. According to one of our volcanologists, it is a “life-changing image”. Note: no New Zealand volcanoes or kittens were harmed in making the t-shirt.
While this t-shirt isn’t very serious, we take improving our website very seriously. So, go on, fill out our survey and be in to get this amazing t-shirt (exchanges are available if you don’t want to be seen rocking a kitten coming out of a volcano t-shirt).