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Facts about the earthquake
The highest level of impact from our felt reports is one report of strong shaking in Kaikoura. This earthquake was felt widely throughout the central New Zealand, on both the North and South Island. So far we have received more than 3,000 felt reports and climbing.
This quake looks like it is in a similar location to the M6.2 quake last year in April.
PGA (Peak Ground Acceleration) was 0.1g (acceleration due to gravity), 10 km from epicentre. Christchurch 22 Feb. 2011 was over 2g. Cook Strait Earthquake was 0.2g.
There was a "ghost quake", magnitude 4.1 earthquake in Wairoa that has now been deleted.
Regarding Aftershocks. We typically don't feel a large number of aftershocks from this type of earthquake. This is because the earthquake was fairly deep and quite remote.
Here is the breakdown of 2015… in terms of geological action for New Zealand.
Volcanoes: Turned down in 2015 but still on “simmer”
Like 2014, volcanic activity was relatively minor in 2015. We had a burst of seismic activity at March but by the end of April, it had gone back to sleep. In August, low gas emissions and seismic activity pulled Mt. Tongariro’s alert level down to 0 on the Volcanic Alert Level (VAL) scale. This was the first time since before the eruptions in 2012 that the level has been back to 0. White Island continued to puff and splutter away, with typical hydrothermal activity and periods of increased tremor continuing throughout the year, but no eruptions. All other volcanoes were quiet. Mt. Ruapehu’s Crater Lake experienced high and low temperatures and a snow and ice avalanche entering and temporarily cooling down areas of the lake by a few degrees. in
What 2016 will bring is unknown but the GeoNet monitoring team continues to keep a close eye on New Zealand volcanoes.
Earthquakes: South Island dominates in Quake Stakes
2015 had a shaky start, with the magnitude 6.0 Wilberforce Earthquake. The South Island continued to dominate in the larger earthquakes stakes, with 6.2 earthquake between Kaikoura and St. Arnaud in late April. The South Island continued to rumble when the 5.8 Matukituki quake, near Wanaka, struck a week later. Fortunately, no major injuries or damage was reported from any of the quakes.
After May, New Zealand quieted down, with no major earthquakes (more than a 6.0) reported for the rest of the year. As far as the bigger quakes this year, overall, there were 43 quakes that measured more than 5.0. 31 of those 43 were far offshore, in the Kermadec Islands. The North Island was relatively quiet in 2015, with three quakes more than magnitude 5.0 striking on land while the South Island had double this number, with six in 2015.
Generally, 2015 turned out to be quieter than 2014. Total quakes this year was 20,008, which was slightly less than 2014, which had 20,711.
So what does this mean for 2016? Unfortunately, there is no crystal ball to tell us what our Shaky Isles will do next.
Landslides: Triple Threats
This year, our landslide team had a full plate with landslides caused by earthquakes, massive storms and volcanoes. We had three magnitude 6.0 earthquakes this year, as discussed in the previous section, that triggered landslides and slips in their respective areas.
But the serious action came this year from massive storms, including Tropical Cyclone Pam. Pam wasn’t the only storm to grace our shores this year with large storm and rain systems, which created considerable sized floods in the Manawatu region, also generated the largest landslides and slips. We also responded to the rainstorm that affected the Hutt Valley and Kapiti coast in May.
Interestingly, this year, we also had a landslide caused by a volcano! White Island’s activity generated a landslide which required further investigation.
2015 was a busy year but we were fortunate that no one was injured as the land continued to slip and slide away.
Slow-slip earthquakes: when the earth moves very slowly
In 2015, our slow-slip earthquakes didn’t prove very exciting, as there were two slow-slip events that went on without any acknowledgement.
In Manawatu, a slow-slip earthquake started in mid-2014 and continued for the first half of 2015. Land around Manawatu moved up to 15cm to the east, which is about the length of a Crunchie bar.
In June of 2015 there was also a small slow-slip earthquake offshore of Gisborne. Land in this area is very slowly being pushed west by the colliding tectonic plates. However, land movement reversed direction for around a month and our stations moved 5-10 cm to the east. The amount of movement pales in comparison to the previous slow-slip earthquake in the area, where land moved up to 30 cm. This pattern of large slow-slip earthquakes interspersed by one or two smaller ones is a constant pattern for this area since these were discovered in the early 2000s.
Tsunami: long distance water hug from Chile
GeoNet responded to one tsunami last year – generated by a magnitude 8.3 earthquake off the coast of Chile. The tsunami experts panel estimated wave heights between 0.2-1m for much of the East Coast and the Chatham Islands, necessitating the Ministry of Civil Defence and Emergency Management to issue a beach and marine threat, that was in place for nearly 24 hours.
The resulting tsunami was consistent with the panel’s estimates, with the Chatham Islands receiving the largest wave heights – close to 1m. The maximum tsunami height on the East Coast of the mainland was closer to 50cm. Although 50cm doesn’t sound like much, it’s important to remember this is not a single wave, but a surge of water travelling faster than we can run.
Best cam shot of the year:
And that’s it! 2015 was a quieter year than the year before…but we like quiet years. But just because 2015 was quieter, it does not mean that 2016 will be the same.
As announced by Google New Zealand last week, we have been able to distribute our quake information even further thanks to our partnership with Google Public Alerts. Notifications can be received on Android smartphones, or the details found using Google Search or Google Maps on other devices or desktops.
Besides the basic facts, you will also get a map showing the region likely to have been most affected, the likely impacts, and recommended advice from the Ministry of Civil Defence & Emergency Management about what to do during and after an earthquake.
GeoNet is the latest of a number of organisations across the globe that contribute their alerts. These include weather, fire and public safety messages. What these alerts have in common is that they use a messaging standard called CAP (Common Alerting Protocol). Details of GeoNet's quake CAP feed are documented at our new API service. This is our go-to place for all of our services related to web and mobile content – watch it grow! Thanks to our funding agency EQC, these data resources remain free to use by anyone.
Featuring: GeoNet Quake app gets new features, The South Island's shaky start to the year, Ngauruhoe unrest tests the revised volcano alert system, White Island landslide hazard, Strong-motion renewal keeps GeoNet ready, Mystery device emerges at Lauder.
Previous issues can be found on the archives page.
A snapshot of earthquakes in 2014
The year started off with a bang with a magnitude 6.2 near Eketahuna on 20 January. With such an early large quake, here at GeoNet we were bracing for another seismically busy year. Since 2009, New Zealand has had a string of large earthquakes and associated aftershock sequences. But it turned out that the Eketahuna quake was the biggest earthquake, in terms of impact and felt reports, this year. The largest quake, in terms of magnitude, was the 6.5 off the north east coast, near Gisborne.
After a positively explosive previous two years with plenty of activity, volcanoes quietened down again this year. Te Maari crater, part of Tongariro, continued to de-gas away but without the more extreme eruptions from 2012. White Island had erupted several times during 2013, and was at a state of heightened unrest throughout 2014, although this decreased throughout the year. Ruapehu also remained relatively at rest this year.
The Monowai Volcano
The most active volcanoes this year were ones you couldn’t see. Monowai, one of our submarine volcanoes approximately 1500 km north-north-east of Auckland, has been erupting often during the past year. The last few days have provided some stunning examples of undersea volcanic activity with the eruption breaking the surface of the South Pacific Ocean in Tonga. We’ll continue to help monitor this volcano as it continues to erupt.
Our landslide team was pretty active this year, with large landslides created by the Eketahuna quake in January, as well as the usual weather events creating havoc around the country. The Dart River Landslide also further developed during January 2014. One of the more interesting landslides this year was the Aoraki/Mount Cook rockfall in July. This rare event damaged a Department of Conservation hut.
This year was a quiet one for tsunami monitoring in New Zealand with only one advisory. But there were big changes in the Pacific Tsunami Warning System and for New Zealand. These changes were inspired by the Indian Ocean Tsunami in 2004; last week marked its 10 year anniversary. Read Ken Gledhill’s Science in Action blog to find out how GeoNet has made changes to our system since that fateful day.
The Silent Earthquakes
One of the most intriguing phenomenon to be studied during the last decade is the slow slip event or SSE. We often refer to these as “silent earthquakes”. A couple of slow slip events were recorded on our GPS network this year. The slow slip event off the coast of Kapiti is ongoing; it has been moving for 18 months or so. Gisborne experienced its own slow slip event this year, which lasted approximately five weeks, moving the coast about three centimetres further east.
Changes to the System
While our volcanoes were quieter this year, we were active behind the scenes, developing better ways to communicate what our volcanoes were up to. The big change during the year was the adoption of a revised Volcanic Alert Level (VAL) system for New Zeland. A Volcanic Alert Level system was first developed before the Ruapehu eruptions of 1995, and had since been used for eruptions at Ruapehu, White Island, Raoul Island and Tongariro (Te Maari). That system was reviewed between 2010 and 2014 as part of a research project that looked at improving the communication of information about volcanic activity.
The new Quake App
Another new system went live this year: the Tongariro Eruption Detection System or TEDS. This system notifies us that an eruption has occurred within seconds. The small, but unfortunately fatal, eruption of Ontake volcano in Japan in September illustrates the potential consequences of small unpredictable eruptions. Once we get this warning, we notify the Department of Conservation (DoC), who then coordinate a rapid response. This system owned and operated by DoC but built on GeoNet equipment and infrastructure and supported by GNS Science.
The Best Cam Shot Award Goes to…
We get some…interesting cam pictures from time to time, especially from the intrepid volunteers on Raoul Island. This year, we thought we’d make an award out of it, given the amount of pics that were taken on the island. So…the best cam shot of the year award goes to:
The mysterious Raoul Island Fern Goddesses!
The Raoul Island Fern Goddesses
And that was the year that was 2014. It may have seemed a bit quiet to some people but we have been busy behind the scenes, improving, tweaking and enjoying running the GeoNet project for you.
Thanks for your support this year and here is wishing everyone a safe and happy 2015!
This will allow the project to obtain higher-quality access to third party networks, both to access data from our instruments around New Zealand and to better utilise offshore cloud services. It also gives us increased network bandwidth diversity, thereby increasing the resiliency of the project.
Since the beginning of GeoNet in 2001, our backup site for data centre activities and networking has been GNS Science's Wairakei office. Moving much of the core communications infrastructure to Auckland while lowering the footprint at Wairakei also allows quicker and more reliable access to our equipment should an unexpected issue arise, especially as same-day support from our suppliers has been unobtainable at Wairakei.
What does this mean for you? You shouldn't notice a thing: that means it's working!
Since the start of the Cook Strait earthquake sequence, the most common feedback we've had about the website was that a list of 30 felt quakes was not enough. During New Zealand's normal background level of earthquakes a list of 30 felt quakes for a region will span days to weeks. But when there are a flurry of aftershocks like we've been having around Seddon and the Cook Strait, the list of 30 felt quakes may only cover a few hours.
We understand that if you're in bed or out and about and you feel an earthquake you still want to be able to find it on our website, and you'd like to easily revisit the significant quakes.
Check out the changes we've made to the felt lists for the regions around the country, there are examples in the figures on the right. You can now select the minimum intensity of the earthquake that you want to look at, so weeding out the smaller or more distant quakes. The list includes up to 30 quakes in your chosen category, going back one year.
One interesting feature about the pages is the list of quakes you will see. Not only will it show quakes in your own region but it will have earthquakes that could have been felt somewhere in your region but occurred in a different region. An example is in the screenshot to the right of the current list of felt earthquakes in Auckland - the large M6.5 Seddon quake is in the list as it's region intensity for Auckland and Northland is weak.
A couple of weeks ago we also added searchable maps to the website, again letting you turn off and on different intensity earthquakes.
For those of you using the geonet.org.nz website this afternoon, you may have noticed a few issues - we are really sorry about this.
The GeoNet website experiened disruptions for around an hour because the provider that hosts our servers went down. We were able to run our backup website so all the earthquake information was kept up-to-date, but it did break some pages and links. We also couldn't record any felt earthquake reports, send out earthquake tweets or send push notifications on the mobile app.
Again, we are sorry for this disruption and hope it doesn't happen again, but rest assured if it does we are still able to keep our eyes on the country's earthquakes and volcanoes.
We have listened to feedback from our valued users and have now added Volcanic Alert Levels to the homepage, with a link to Volcanic Alert Bulletins. Now when you visit Geonet.org.nz you will see the latest earthquake activity, as well as the current status of our volcanoes.
We have also added a new tab and link on the Volcanoes page which take you to the Volcanic Alert Bulletins, so during a volcanic event people can easily find the latest information.
We will continue to work on ways to better show you our valuable data via our website, on both mobile and computer devices, and look forward to bringing out a faster more interesting way for people to complete 'felt it' reports on their mobiles via our free app 'GeoNet Quake' later in the year.
GeoNet News - Issue 17, Feb 2013 (971 kB)
This issue is all about out Volcanoes - Including the recently active Tongariro and White Island, the Monowai Submarine Volcano, Volcano Gas flights - what are we measuring? And the faces behind
The New Zealand Open Source Awards 2012 were made on November 7. They recognise and promote the contributions of New Zealanders to free and open source projects and free and open source philosophy. We are proud to say we picked up two awards on the night:
- Use of Open Source software in Government: our nomination was for GeoNet Rapid, our state-of-the-art, fast and innovative earthquake location and information system that is a key component of the GeoNet Project. The primary aim of GeoNet Rapid is to make earthquake locations available via the internet faster - specifically within five minutes or less of an earthquake occurring. A key component of GeoNet Rapid has been to make earthquake information available across a variety of platforms including smart phone applications for Android, iPhone, and iPad.
- Use of Open Source software in Science: our nomination was for GeoNet's Open Data policy, which makes all data and information freely available to all. The free access to information has proved its value many times over during the period since the Christchurch earthquakes. It has allowed the creation of many data visualisation websites and projects as well as numerous scientific publications, special journal editions and presentations that make use of data from GeoNet.
In both cases the foundations for the initiatives were laid many years ago by people with foresight and dreams; we would like to acknowledge all who have played their part along the way to where we are today.
Previously you waited until the Duty Officer had manually checked the earthquake before you received any details. With our automated system you can get details much, much sooner. Sometimes a bit too soon; we've since modified our alerts to wait until we've received sufficient data to be more confident in our notifications. Remember it's still preliminary at that stage, and it's best for you to check back with the website to see the latest and best information.
Earthquakes Prior to 2012
Our old website only featured web pages for earthquakes that were felt or likely to have been felt. Now every earthquake in the New Zealand catalogue has its own page.
How do I find the page? If you know the earthquake's Public Id (also sometimes called CUSP Id or Reference Number), then type the web addressinto your browser, for example:
- New style Public Id: http://www.geonet.org.nz/quakes/2012p789042
- Old style Public Id: http://www.geonet.org.nz/quakes/1550210
Felt Report Maps
Yes, each of these pages will also show all the felt reports in our database. Check out some of the Historical Quakes - go to the GeoNet Summary link.
The Simple Queries facility is used by a lot of you for getting a list of earthquakes from the New Zealand catalogue. At the moment it only returns earthquakes up until our go-live date of September 5, 2012. You can now also use our Web Feature Service to query both old and new earthquakes and return them in a variety of formats.
For researchers, we've added the new Public Ids into the waveform retrieval client; at this stage P and S picks are not available for these but they're in the pipeline.