Earthquakes haven’t gone away

People in North Canterbury, Marlborough and the Wellington region, and further afield,  were reminded that the earthquake onslaught isn’t over yet. The more significant quakes over the weekend:

  • 4.6 (strong) 30 km south-west of Wellington – Sat, Nov 26 2016, 3:22:03 am
  • 5.1 (severe) 35 km north of Wairoa – Sat, Nov 26 2016, 8:21:42 pm
  • 3.9 (moderate) 20 km south-east of Culverden – Sun, Nov 27 2016, 8:25:29 pm
  • 4.5 (moderate) 35 km west of Paraparaumu – Sun, Nov 27 2016, 9:31:11 pm
  • 4.1 moderate) 20 km south-east of Seddon – Sun, Nov 27 2016, 9:33:28 am
  • 3.7 (moderate) 10 km south-west of Kaikoura – Sun, Nov 27 2016, 7:46:44 pm
  • 4.8 (strong) 15 km east of Seddon – Sun, Nov 27 2016, 9:42:16 pm
  • 4.1 (moderate) 20 km south-east of Seddon – Sun, Nov 27 2016, 10:05:32 pm

The latest from 7 am update:

  • 125 earthquakes in last 12 hour
  • 220 earthquakes in last 24 hrs (4 over M4)
  • 6159 earthquakes since the M7.8 Kaikoura Earthquake.

geonet2016november28

So while in general the frequency and size of the quakes is gradually easing off it is not all over yet, and periodically some bigger quakes come back to remind those in the shaking region.

Geonet still predicts an 81% chance of an M6-6.9 shake in the next 30 days and 99% in the next year, and a 34% chance of a greater than M7 in the next year.

Geonet: Latest Updates and Scenarios and Probabilities

Cross-party support for earthquake legislation

Parliamentary parties are working together on emergency legislation to help sort things out after the earthquakes.

NZ Herald: Emergency quake legislation on the way after cross-party meeting

The Government has today met with opposition parties to discuss what emergency legislation could be introduced to skirt usual consenting processes and aid the earthquake recovery.

A spokeswoman for Acting Civil Defence Minister Gerry Brownlee confirmed the approach.

“There was a cross-party meeting this morning to discuss legislative options but it is very early days.”

Labour Party leader Andrew Little, speaking to the Herald from Kaikoura, has indicated his party will support the emergency legislation.

“The Government put up the things they have in mind. All the parties were there. There are more meetings to go before legislation is introduced, which the plan is to be next week.

“We have indicated support, subject to appropriate checks and balances…but our people who were [at the meeting] described it as constructive.”

It’s good to see this inclusiveness, putting the needs of the affected people and regions first.

Little said he believed the Government had learned lessons after the introduction of emergency legislation following the Canterbury earthquakes.

“I think it [emergency legislation] is natural in order to get stuff done – particularly now you have a town the size of Kaikoura and its importance to the tourist industry totally isolated at the moment, you do want some expedited powers.

Little has taken a responsible approach to the earthquakes, and has been included from the start by the Government in assessing the damage and the problems.

The Whale Watch boat berths have been uplifted and can now only be used at high tide.

Yesterday Little said that repairs to the harbour at Kaikoura should be fast tracked rather than go through a lengthy consent process so that tourist and fishing businesses can resume as soon as possible.

But there may be some tensions.

The road freighting industry has lobbied the Government not to be “sensitive” about repairing SH1 and to bulldoze rubble into the sea.

Some of the slips have already covered sea shores. If they were left to weather naturally there would be further subsidence into the sea, it is part of normal erosion processes. But:

Green Party primary industries spokesperson Eugenie Sage said today that view was shortsighted.

“Fixing the road and rail links is obviously quite critical and urgent, but dumping thousands of tonnes of rubble into the sea risks killing the goose that lays the golden egg.

“Nature-based tourism, whale-watching, swimming with dolphins and fisheries like the cray and paua fisheries are absolutely critical to Kaikoura’s economy.”

Whales and dolphins shouldn’t be an issue, they are found further out to sea.

Seals congregate and breed on the rocky shores. They will have been affected but their numbers have increased markedly over that last fifty years so should have no trouble re-establishing themselves.

The crayfish and paua fisheries have already been badly affected by the natural affects of the earthquakes, in the main by uplift of shallow shores.

“We don’t want to reestablish the transport link at the expense of a healthy coastal marine environment and healthy fisheries.”.

In the main it’s unlikely that pushing slip debris a bit further out into the sea will have a major effect. Obviously they will have to take care if any of the slips are in ecologically sensitive areas, but the vast majority of the coastline will remain unaffected by slip debris.

It will be good if all parties are on board with emergency legislation.

Earthquake problems continue

Most of New Zealand has more or less put the earthquakes behind them,  but there are significant ongoing problems.

An aftershock in North Canterbury yesterday evening seriously damaged houses and forced evacuations, and also held up access to Kaikoura via the inland route.

There is no sewerage system in Kaikoura, they are running out of water and fuel, and frustration grows for those who want to get out by road but aren’t allowed.

This afternoon Goose Bay was evacuated after a warning a slip created dam might burst.

The NIWA building in Wellington was shut today pending a proper building inspection.

And tonight another building in Wellington was evacuated due to fears that it’s stairwells were damaged.

RNZ: Wgtn’s Asteron Centre evacuated over quake risk

Wellington’s 17-storey Asteron Centre has been evacuated over possible earthquake damage to its stairwells.

The high-rise, described by its designers as the capital’s largest single office building, is located opposite the Railway Station.

Updates from Geonet continue.

This simulation shows how the seismic waves of the magnitude 7.8 earthquake were propagated across New Zealand.

This also shows how the initial quake dominoed it’s way up the South Island from Culverden to Seddon: Watching the M7.8 Kaikoura Quake Dominos Fall in Real Time

And  How is the Kaikoura aftershock sequence behaving compared to the forecast?

By noon on Wednesday 23 November we had detected 4879 aftershocks from the M7.8 Kaikoura earthquake (with the area of detection being the forecast area represented by the box). 

Most of these aftershocks have been small (4828 earthquakes <M4.9) and would have only been felt close to the epicentre.

As of Monday 21st, there were also 47 aftershocks in the M5.0-5.9 range, and 3 aftershocks in the magnitude M6.0-6.9 range.

That sounds a lot but:

At the moment, the aftershock sequence is falling within the lower end of our forecasted range.

What does this mean?

In summary, the aftershocks are at the lower end of the forecasted range. It is a bit puzzling and we are scratching our heads at this one. What we can say is that just because we are in lower end of the forecast, it doesn’t mean that this will stay that way.

Pretty much anything could happen from here, from less and less to substantially more.

All we can do is be wary and be prepared.

North Island slow-slip follows South Island quake

There has been a lot evidence of land movement during and after what is now referred to as the M7.8 Kaikoura earthquake – it was initially said to be centred close to Culverden and Geonet still shows it as ’15 km north-east of Culverden’ (Kaikoura is about four times further away).

It is thought that the initial quake caused a chain reaction along other fault lines in the South Island, and Wellington was also affected.

Geonet has now revealed that since this movement happened there has been a ‘slow slip’ occurring further north, along the Hawkes Bay and Gisborne coast. Slow slips have been detected there before but only after North Island earthquakes.

Today Geonet posted on Coastal Uplift: How has the Kaikoura Coastline Changed which shows the extent of land movement over a large area of the South island.

Much of the northeastern coast of the South Island was uplifted during the 14th of November 2016 earthquake. We know this from photos of rock platforms covered in seaweed and marine animals such as crayfish and paua stranded above tide levels.

Our records measured the tide gauge at Kaikoura was lifted up by 1 m, and continuous GPS monitoring sites at Kaikoura and Cape Campbell were also raised by 0.7-0.9 m. At this stage we can estimate that the coast was raised between 0.5 m and 2 m from about 20 km south of Kaikoura all the way north to Cape Campbell.

The startling uplift of ~5.5 m at Waipapa Bay is a localised block pushed up between two traces of the Papatea Fault and is thankfully not representative of the whole coastline.

There was greater horizontal movement, reported to up to 10 metres in places. All those ground movement happened along a long stretch of coastline up the north east of the South Island.

kaikouraearthquake_uplift_21nov2016

Uplift and horizontal movement happened on a long stretch of coastline up the north east of the South Island.

Also today Geonet posted Gisborne and Hawke’s Bay slow-slip event follows M7.8 Kaikoura Quake

GPS stations have detected a slow-slip event under the Hawke’s Bay and Gisborne regions in the days following the Kaikoura M7.8 Earthquake.

These silent earthquakes or slow-slip events are undetectable by both humans and GeoNet’s seismographs. They can move faults the equivalent of magnitude 6+ earthquakes over a period of weeks to months, without any detectable shaking.

The ongoing slow-slip event off the North Island’s east coast has moved some GPS stations up to 2-3 centimetres.

So far. It’s only a week since the M7.8

This movement is similar to what has been observed in previous East Coast slow-slip events over the last 15 years, so is not necessarily abnormal. We see events in this area usually every 1-2 years.

We have also observed other slow-slip events happening in response to large earthquakes.

The last slow-slip event offshore of Gisborne followed the Te Araroa earthquake in September 2016 (related GeoNet story http://info.geonet.org.nz/x/ZIAvAQ).

A slow-slip event also occurred following the 2007 M6.7 Gisborne earthquake.

But this time the slow-slip began after a more distant quake.

It is possible that passing seismic waves from the M7.8 earthquake caused stress changes that triggered the slow slip event. GNS Science and GeoNet and scientists are keeping a close eye on the event as it evolves.

So the Culverden quake may have triggered the Kaikoura and Seddon quakes (and three other fault line breaks), nudged across Cook Strait to Wellington and may rearranged stresses enough up the east coast of the North Island to start the slow-slip.

slowslip_hb_and_gisb

This instability covers a large area in which many of New Zealand’s significant earthquakes have occurred.

nz_faults

The initial Culverden quake was on the Hope fault line which reaches back to the top of the Alpine Fault where it breaks apart into Marlborough’s mess of mountains.

Also today Geonet updated it’s statistics based scenarios and forecasts which includes the probability of aftershocks:

  • 99% M6.0-6.9  in the next year (89% within 30 days)
  • 38% >=M7 in the next year (20% within 30 days)

There is no way of knowing, if another large quake occurs, where it would be. There is a lot of uncharted territory here.

What to do about it?

If you feel an earthquake:

Don’t run outside, many injuries are caused by things falling from buildings. Beware of breaking glass.

And if you are close to sea level near the coast don’t wait for a knock on your door or a warning siren, move inland or to higher ground.

And hope that the slow-slip eases the pressure gradually so nothing major gives suddenly.

Whale watched off Kaikoura

There were concerns that whales might have been frightened off by the earthquakes, but Whale Watch Kaikoura have been out to sea to check and have spotted a sperm whale.

Today 6 days after the 120sec that changed our lives we decided to journey off the Kaikoura coast and look for our taonga and whanau the Tohora, im sure you can appreciate the huge excitement when we found him. What an amazing sight to see that our Tohora is still with us.

We know Hector Dolphins and Dusky Dolphins have also been sighted along with huge numbers of albatross and other pelagic seabirds, our canyon is still full of life!!!

It could be a long time before many tourists are out off Kaikoura again but at least there’s still whales there.

Earthquakes continued

News coverage of the earthquakes is slowing down, as are the earthquakes, but there are still many shakes.

5.30am update: 9 earthquakes in last hour, 238 earthquakes in last 12 hrs (only 2 over M4) and 3646 earthquakes since the M7.8 Kaikoura Earthquake

The pattern is the same, scattered along the Hope fault line where the initial quake was, and clusters around Kaikoura and Seddon.

cxo5j3qveael6nz

That looks very similar in pattern and number to yesterday morning. There are still some sizeable shakes (for those close enough to feel them).

There’s a few reaching up into Wellington and also another near the Alpine faultline.

The bigger shakes over the last day and a half:

  • 3.8 (moderate) 10:11:48 pm 5 km north-west of Seddon
  • 4.6 (strong) 2:30:10 am 20 km west of Kaikoura
  • 3.8 (moderate) 3:21:22 am 5 km north-west of Culverden
  • 5.0 (strong) 3:22:58 am 20 km north-east of Cheviot
  • 4.4 (moderate) 4:17:32 am 15 km south-east of Seddon
  • 4.8 (strong) 4:55:34 am 25 km east of Hanmer Springs
  • 4.2 (strong) 4:08:10 pm 20 km north-east of Kaikoura

They mightn’t seem much but to those feeling them they are repeat reminders of what is still going on beneath them. I’m sure some aree wondering with each one if it is going to be an anticipated big aftershock.

Stuff interactive: The Mountains Moved 14.11.16

Stuff: Timeline of the 7.8 quake and response reveals plenty of room for improvement

The huge earthquake that hit New Zealand this past week, buckling roads, uplifting sections of coastline and killing two people, also exposed problems in how the country monitors its earthquake risk and prepares for tsunamis. And it raised questions about whether the city of Wellington put people at risk by reopening buildings too soon.

The nation was spared the devastation of five years ago when 185 people were killed in the Christchurch earthquake. But some consider it was more by luck this time than by good planning.

Here’s what happened, minute by minute, after the quake hit early Monday, with details on how officials intend to improve

RNZ coverage:

Aid convoy forced back

A large convoy of army trucks carrying urgent supplies used the rural road yesterday, but Civil Defence said there was still a significant threat of landslides.

Military vehicles could not longer use the inland road because of the threat of more slips.

One aid convoy arrived in Kaikoura last night, but a second had to turn back.

Acting Civil Defence Minister Gerry Brownlee said the route would like open in the middle of next week.

The earthquake aftermath in pictures

RNZ visual journalist Rebekah Parsons-King has captured the cracked roads, landslips, and damaged railway lines from the air and ground, after a 7.8 magnitude earthquake hit early on Monday morning.

Cordon in Wellington CBD to be reduced

One of the cordons in central Wellington will be reduced, as city authorities defend the handling of the risk of quake-damaged buildings in the capital.

 

 

Tough outlook for earthquaked towns

The towns worst affected by this week’s earthquakes are having to deal with massive problems with damaged houses and wrecked infrastructure.

One of the biggest problems facing their recovery will be business, and that is affected substantially by inaccessibility due to wrecked roads, especially in Kaikoura.

Getting good access from the south will be difficult enough (a rough inland road for emergency access only has been opened) but getting a through road will be a major challenge.

kaikouraroadslip

One of a number of landslides blocking the Kaikoura coast road.

RNZ: Kaikoura fears becoming a ghost town if State Highway 1 ‘lifeline’ stays closed

Kaikoura business owners say the town could die once the relief runs out, and only reopening State Highway One will save it.

SH1, the main route to Kaikoura from the north and south, is closed. It sustained significant damage, with cracks, fissures and landslides. The New Zealand Transport Agency said restoring full access would take several months.

Damage to sea life, the fisheries industry and wildlife will affect the town’s biggest tourists attractions, such as whale watching, dolphin encounters and the seal colony.

Kaikoura will be badly affected without tourism. They are certain to lose this summer’s trade.

Dwayne Fussell owns Coastal Sports. He has lived in the town for 15 years and is raising a family.

The town’s businesses were seasonal. They made money over summer and struggled through winter, he said.

“If you don’t make that [money] through the December, January months, you’re not here the following summer.

Only reopening SH1 would bring the visitors back, he said. If the tourists stayed away, the businesses would disappear.

“SH1 is our lifeline. We need it,” he said.

Unless the main highway is reopened right up the coast to allow through traffic – and months to repair it looks very optimistic – then Kaikoura is in trouble.

Even when the highway is reinstated they will require costly repairs and re-establishment of facilities. Some of the coastal fisheries and wildlife will have been badly affected by the earthquake, but it is unknown at this stage how the big draw cards, the dolphins and especially the whales will have been affected.

And even with facilities and roads restored they will have to overcome fears and a reluctance of tourists to venture down a very risky looking coastline.

Hamner Springs is another town reliant on tourism. Even though they weren’t far from the first earthquake epicentre the town was remarkably unscathed and has reopened for business, but through a combination of fear of more earthquakes and a lack of coastal through traffic they are suffering.

Newshub: Hanmer Springs a ‘ghost town’ – business owners

Hanmer Springs businesses are desperate for tourists to visit after a large drop in numbers following Monday’s 7.8 magnitude quake.

The quake was centred about 25km southeast of Hanmer Springs, but despite its proximity, the village suffered very little damage.

Hanmer Springs Thermal Pools and Spa general manager Graeme Abbott says there’s been a noticeable drop in visitors.

On a “normal day”, he would expect between 500-600 visitors, but on Tuesday he only had around 150.

“It’s gradually climbing up but still nowhere near what we would usually expect,” Mr Abbott says.

“The reality is we had a major earthquake here and power outages and road closures so people couldn’t get here, but that’s all cleared up now.”

Mr Abbott says there is no need for people to stay away from Hanmer Springs.

“The village is undamaged. All the businesses are open.”

In time it mightn’t be so bad for Hamner as the detour south runs near them – in fact it might improve things for them as tourism flows pick up.

But Kaikoura especially, and other towns and regions on the coastal route like Cheviot and the Waipara wine region to the south will find business tough for a year or two at least.

To the north some Marlborough vineyards and wineries were damaged by the earthquakes, and the Picton to Christchurch detour route that goes nearly to the West Coast and back across Lewis Pass, bypasses Blenheim so they are also likely to be affected there.

It’s interesting to see Google Maps and the AA Route Finder showing the detour rather than the munted coast road already. The detour extends the normal 350 kilometre trip to 480 km, and obviously misses all the coastal scenery.

Other regions will probably benefit, but the affected towns and area will struggle to survive as they were.

Measuring the ground movement

Geonet have been busy measuring how much the ground moved in this week’s earthquakes (it is still moving in some parts).

GPS allowed rapid detection of land movements due to M7.8 earthquake

Within a couple of hours of the M7.8 earthquake, GeoNet was able to use the GPS data to estimate the initial displacements of the Earth’s surface that occurred during the earthquake.

kaikouraearthquake_web_18nov2016

What the GPS revealed was astonishing. It turns out that the earthquake shifted the land at Cape Campbell (the northeast tip of the South Island) to the north-northeast by more than 2 m, and up vertically by almost 1 m.

This means that Cape Campbell is now more than 2 m closer to the North Island than it was before the earthquake. Similarly, Kaikoura has moved to the northeast by nearly a metre, and has been lifted upwards by 70 cm.

Hanmer Springs, which was our closest GPS site to the quake epicentre, jumped eastward by approximately 50 cm. All of this movement happened during the earthquake in a matter of seconds.

A lot more of the country moved to a lesser extent.

Not only did the earthquake shift landmasses in the northern South Island, but it also caused movements across most of the country.  

gps3

In the lower North Island, the east coast has shifted west by 1-5 cm, while the Wellington and Kapiti regions were shunted 2-6 cm to the north. Christchurch and Banks Peninsula didn’t miss out on the action, either—they are now approximately 2 cm further south than they were the day before the quake.

Some parts of the west coast of the South Island have been shifted eastward by as much as 10 cm. The northern North Island and southern South Island only moved a few millimeters.

Satellite mapping shows horizontal movements.

cViewing the M7.8 Kaikoura earthquake from space

A technique called InSAR, which stands for ‘Interferometric Synthetic Aperture Radar’, utilises radar satellites orbiting ~700 km above the earth to precisely measure the distance between the ground and the satellite. If the ground moves between two subsequent satellite passes, due to an earthquake or volcanic eruption, then the distance between the ground and the satellite changes. Observing these changes in the positon of the land with InSAR enables us to generate detailed maps of ground movement, often with centimeter-level accuracy.

The satellite images reveal huge changes in land movement across the Hope and Kekerengu faults, as well as several other faults in the region. 

To the east of these faults, the land went mostly southwest (see blue area in the figure on the left). In contrast, to the west of these faults the land moved mostly northeastwards (see red area in figure on left).

Sharp changes in land movement are visible on the InSAR images, and show us where the faults ruptured to the Earth’s surface.

insar_1_cropped

Horizontal offsets from radar data. The red colours show up to 5 m of horizontal motion of the land towards the north-east and blue colours show up to 6 m of land movement to the southwest. The yellow lines show faults that appear to have ruptured.

insar_2_wtrmkd

An interferogram generated using data from a Japanese Space Agency satellite. Each set of rainbow-coloured contours represent 11.5 cm of movement. Where the colored contours are closest together is where the largest changes in land motion are occurring.

These are different ways of showing ‘much munting’.

And there is likely to be more to come, although hopefully to a lesser extent.

‘God deeply frustrated with Auckland’s gay people’

This is the best response I’ve seen.


God is reportedly feeling “extraordinarily” frustrated that the gay people of Auckland – estimated to be the large bulk of New Zealand’s gays – are located nowhere near a fault line that could cause them sufficient devastation.

God, who punished Christchurch’s gays in 2010 and 2011, Seddon’s gays in 2013, and Kaikoura and Wellington’s gays earlier this week…

Go read it all: God deeply frustrated Auckland’s gay people live nowhere near a fault line

And here a couple of people explain how Tamaki doesn’t understand Leviticus: Porkies, Brian, Porkies!

 

Earthquake update – Thursday

Geonet 5 am Thursday update:

  • 19 earthquakes in last hour
  • 290 earthquakes in last 12 hrs (11 over M4)
  • 2070 earthquakes since the M7.8 (570 since 4 am Wednesday)

The rate and size of quakes is slowly reducing. The larger quakes overnight:

  • 4.3 – 7:45:51 pm 20 km south of Seddon
  • 4.3 – 7:46:33 pm 20 km north-east of Kaikoura
  • 3.8 – 9:27:10 pm 5 km north of Culverden
  • 4.8 – 10:15:14 pm 20 km east of Martinborough
  • 4.3 – 1:19:45 am 30 km north-east of Arthur’s Pass
  • 3.8 – 3:20:09 am 25 km north-east of Hanmer Springs
  • 4.0 – 3:41:33 am 30 km south of Seddon
  • 4.9 – 4:03:49 am 20 km south-west of Kaikoura
  • 4.0 – 5:02:32 am 10 km north of Culverden

Notable points: while reducing in size they are still spread over the three main areas, Culverden/Hamner, Kaikoura and Seddon, but with two other locations, east of Martinborough on the Wairarapa faultline (the one that went M8+ in 1855) and one north-east of Arthur’s Pass (Alpine Fault territory).

We can hope that these are reducing stresses rather than increasing them on other faultlines.

Yesterday Geonet upgraded the size of the initial quake (which may have been two consecutive quakes in different locations) from M7.5 to M7.8.

Kaikoura earthquake update: Magnitude revised

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.

RNZ continues to have good coverage, including:

Rescue efforts in Kaikoura continue as helicopters and NZ and US defence force ships arrive in the quake-hit town with supplies.

Wellington is also dealing with the aftermath of Monday’s 7.8 magnitude quake, with several central city buildings deemed unsafe.

The aftermath of the 7.8 magnitude quake so far

Govt to consider funding for 24/7 quake monitoring

‘Absolutely gutted’: Tiny community of Mt Lyford devastated by quake