Mass of quakes continue

When I headlined Earthquake onslaught  that was based on what had happened in the few hours since the 7.5 quake just after midnight, but things haven’t let up all day with hundreds of quakes around the top half of the South Island.

The quakes have often been in clusters alternating between Kaikoura, Seddon and North Canterbury, with a few outliers.

There have just been two more ‘severe’ shakes amongst a cluster:

  • 3.6 (light) 7:37:16 pm 25 km north-west of Cheviot
  • 3.6 (light) 7:38:13 pm 10 km east of Kaikoura
  • 3.4 (light) 7:40:54 pm 35 km south of Seddon
  • 5.6 (severe) 7:43:01 pm 25 km east of Seddon
  • 4.4 (moderate) 7:43:34 pm 15 km north-east of Methven
  • 5.7 (strong) 7:47:51 pm 25 km east of Kaikoura
  • 4.3 (strong) 7:51:58 pm 15 km east of Seddon
  • 4.5 (strong) 7:52:53 pm 20 km east of Seddon
  • 4.4 (light) 7:55:44 pm 35 km east of Kaikoura
  • 3.6 (light) 7:56:19 pm 15 km east of Levin

That’s 10 in 20 minutes. The whole area seems to have become unstable.

And the pictures being published of the roads, railway line and hills shows how unstable the area is on the surface. Huge and smaller slips have blocked roads and lines in many places. It could take weeks if not months to open state highway 1 between Picton and Christchurch reopened.

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Kaikoura is cut off due to major slips both to the north and to the south.

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There was a road and a railway line round here yesterday. And paddocks and stock have also been affected.

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There have been two deaths reported. Given the size of the quakes this is relatively low, fortunately being in the middle of the night in mostly sparsely populated areas helped minimise casualty rates.

But there are many ongoing aftershocks, quite a few fairly strong, and Geonet says there’s a 32% chance of another 7+ in the next month or two.

There have already been six quakes rated as ‘severe’ today, near Culverden, Kaikoura (3), Seddon and Cheviot. There was widespread minor-ish damage in Wellington and they ‘only’ had a 5.3.

What has happened already will have a major impact on Marlborough and North Canterbury and also further down the highway. The alternative routes by land are lengthy, via the West Coast.

And there will understandably be many worried people.

There’s enough cause for concern down here in Dunedin (where some people were woken by the big midnight shake but I haven’t felt a thing) having seem the enormous effects on Christchurch.

There will be many frazzled nerves after a day of sustained shaking in the top half of the South island and the lower North island.

UPDATE: since typing the above list and the rest of the post there has been another  ‘severe’ (5.9) and another ‘strong (5.8) quake near Seddon – they are 30 seconds apart so must just about be the same quake.

Earthquake onslaught

There has been a mass of earthquakes ranging from North Canterbury to the Wellington region, with the biggest ones near Culverden (7.5), Kaikoura (two at 6.2), Seddon (5.3), Wellington (5.3)  and Paraparaumu (4.9).

So far there have been 27 quakes rated severe or strong since midnight.

earthquakes2016-11-14

‘Casualties’ have started to be reported:

Police say one casualty has been reported at a collapsed property in Kaikoura.

Updated – two confirmed fatalities so far.

There was a tsunami warning and 2.5 metre waves were recorded at Kaikoura but that has now been downgraded.

Aftershocks are continuing, and damage is just being assessed in many areas as daylight breaks.

Many roads are closed. Photos are emerging of widespread road damage. A slip has blocked a rail tunnel and the twin road tunnels on the Kaikoura coast road. And the Waiau River bridge may be damaged – this is the main access to Hamner Springs.

The Cook Strait ferries have been stopped and crossings have been cancelled. The passenger bridge in Wellington has been damaged.

Wellingtonians have been advised not to come to work today. Damage in city extensive

People are being advise to stay out of the Wellington CBD until damage has been assessed.

And gale force winds are forecast for central New Zealand today.

Leader rd Kaikoura

earthquakekaikoura

 

So far 30+ (updated) earthquakes rated ‘strong’ and ‘severe’ (there have been many smaller ones), all quite shallow:

  • 7.5 – 12:02:56 am 15 km north-east of Culverden
  • 5.6 – 12:16:10 am 5 km west of Culverden
  • 5.9 – 12:19:32 am 45 km north of Kaikoura
  • 5.6 – 12:24:17 am 40 km north of Kaikoura
  • 6.2 – 12:32:06 am 15 km north of Kaikoura
  • 5.6 – 12:41:48 am 20 km south-east of Seddon
  • 6.2 – 12:52:44 am 25 km north of Kaikoura
  • 5.2 – 1:03:53 am 15 km south-east of Seddon
  • 5.3 – 1:04:21 am 15 km south-east of Wellington
  • 4.9 – 1:11:59 am 15 km south-east of Seddon
  • 4.9 – 1:21:10 am 5 km east of Paraparaumu
  • 5.2 – 1:25:55 am 10 km north of Culverden
  • 5.2 – 1:27:59 am 10 km north-east of Kaikoura
  • 4.7 – 1:31:25 am 15 km east of Seddon
  • 5.2 – 1:37:43 am 25 km west of Kaikoura
  • 5.3 – 1:38:38 am 15 km east of Seddon
  • 5.1 – 1:52:18 am 15 km north-east of Kaikoura
  • 4.6 – 2:12:31 am 10 km south of Seddon
  • 6.0 – 2:31:26 am 15 km north of Kaikoura
  • 5.1 – 2:50:01 am 20 km south-east of Seddon
  • 4.8 – 3:07:22 am 10 km north-west of Culverden
  • 4.9 – 3:08:42 am 20 km west of Culverden
  • 5.3 – 4:33:03 am south-east of Seddon
  • 4.9 – 4:58:01 am 15 km south-east of Seddon
  • 5.1 – 6:17:41 am 10 km south-east of Kaikoura
  • 4.9 – 7:21:41 am 10 km west of Seddon
  • 5.2 – 7:34:26 am 20 km south-east of Seddon
  • 4.8 – 7:58:08 am 10 km north of Wellington
  • 5.4 – 7:58:46 am 10 km south-east of Seddon
  • 5.3 – 7:59:08 am 15 km east of Kaikoura

Remember that these are just earthquakes rated strong or severe and excludes ‘moderate’ and less.

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The per-year movements are averages, the actual movements tend to be far less frequent and larger.

Tsunami warning

Following this morning’s earthquake off the east coast of the North Island there’s been a few complaints about the delay in Civil Defence issuing a tsunami warning.

Newstalk ZB, in Civil Defence response to tsunami threat questioned, detailed the timing:

NZ:Timeline of earthquake response

4.37am earthquake strikes
4.41am – The Ministry of Civil Defence & Emergency Management receives initial notification of a magnitude 6.3 earthquake from GNS Science
4.53am – GNS upgrades quake to a 7.1
These earthquakes did not meet the threshold for automatic issuing of a potential tsunami threat, ministry says
5.10am – Ministry issues an earthquake notification
Pacific Tsunami Warning Centre finds no tsunami threat in their initial assessment
5.33am – Ministry issues national advisory for a potential tsunami threat. Says it’s proactive while awaiting confirmation from scientists
5.58am – A tsunami warning is issued
8.30am – Cancellation message sent at 8.30am.

I think common sense should be used:

If you feel an earthquake take cover as soon as you can – it’s called Drop, Cover, Hold but just immediately protect yourself as well as you can.

Once the shaking has finished take care in case anything has been loosened or weakened.

If you are anywhere near the seashore treat it as a tsunami risk until you fond out otherwise – assume danger unless you are confident it’s safe.

When you can check online or on TV or the radio to see what warnings may have been issued, but if you don’t find any warnings or all clears continue to take care.

Official advice may help, eventually, but don’t rely on it, use common sense.

If I get clobbered by an earthquake or wiped out by a tsunami I would put it down to bad luck, or not being sensible and taking responsibility for myself.

An earthquake should be sufficient warning of potential tsunami risk.

East Cape earthquakes

Mid morning yesterday there was a sizeable  (5.7) earthquake off East Cape, 100 km north=east of Te Araroa.

That has been followed this morning by a much larger 7.1 in a similar area off shore at 4:37 am, and that has been followed by a swarm of quakes, including a 6.2, a 5.1 and a 5.0 – some of these have been centred on land around Ruatoria and Te Kaha.

A tsunami warning was issued belatedly. It was recently reduced to the east of the North Island up to 1 metre.

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The biggest quakes yesterday and this morning:

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The drum at Matakaoa Point shows yesterday’s shale plus this morning’s cluster.

EarthquakeDrumMatakaoaPoint

Quake map for all quakes yesterday and today:

EarthquakesEastCapeSept

http://quakesearch.geonet.org.nz/

Another ‘dirty protester’ attack

There was another incident today of something been thrown at an MP, this time some brown substance at Gerry Brownlee.

At least this time media made the point that it was highly inappropriate at an anniversary commemoration of the Christchurch earthquakes. It was very disrespectful of the occasion.

But this is becoming a bigger problem, where protesters or nutters think that anything goes when it comes to attacking politicians.

I think the police need to start taking strong action or some serious shit is going to eventuate.

And media need to have a serious think about how they deal with incidents.

It’s simply not acceptable that politicians or anyone in public should be physically attacked, whatever the justification.

This ‘dirty protesting’ has already gone too far and there’s a risk of something far more serious occurring.

 

 

Five years on and quakes continue

There was an awful reminder for Cantabrians last week that although a very damaging quake was five years ago it wasn’t a one off event and the after effects still dominate Christchurch.

There have been about 14,000 earthquakes in the area over that time, most centred in or close to Christchurch.

We felt the big ones in Dunedin and they were disconcerting enough but it’s easy to forget the impact on Canterbury from a distance.

Earthquakes and their aftermath are still a big deal. In many many cases nerves and finances are as frayed as the Earth’s crust seems to be.

The Press has a feature to mark this anniversary:

Five years, 14,000 quakes, and a new South Island

While Christchurch and Canterbury has been changed markedly, and a lot of renewal has been necessary, the rest of the South Island has only been affected in relatively minor ways.

The reality is that while I feel for those who have been impacted by the earthquakes, I really can’t know what it feels like for our close neighbours.

It’s easy to forget about the quakes from a distance, apart from occasional reminders like the bigger aftershocks and anniversaries.

The big two from Geonet:

  • M 6.3, Christchurch, 22 February 2011The city of Christchurch experienced a major earthquake centred south of the city; severe damage and casualties occurred.
  • M 7.1, Darfield (Canterbury), 4 September 2010The Darfield earthquake caused severe building damage in mid-Canterbury, particularly to the city of Christchurch. It revealed the existence of a hidden west-east fault under the gravels of the Canterbury Plains.

Five years ago, wow.

More Christchurch earthquakes

Hopes  in Christchurch that their earthquake horrors were over came crashing down to a shaky earth yesterday with another large quake rattling homes and nerves, followed by many smaller quakes.

A 5.7 quake hit yesterday at 1:13 pm, centred just offshore and east of the city.

What GNS can tell us about the severe earthquake that hit Christchurch on Valentines Day.

Source: Stuff – Christchurch hit by severe earthquake

There have been 9 further 3+ quakes since then, and many more smaller ones. This drum from Geonet shows the frequency:

DrumMcQueensValley

I was at home and inside when the 5.7 happened but didn’t feel it. At work in the CBD it’s more sensitive to distant earthquakes and I normally feel them down to about 5.0 from Christchurch.

Damage was mostly only minor, with most vulnerable buildings already destroyed or demolished after the previous major earthquakes, although there were some dramatic looking cliff collapses.

A cliff collapse, as seen from Taylors Mistake.

Damage to people’s nerves is difficult to measure but would have been substantial with this reminder of Christchurch’s vulnerability.

The Christchurch Press has an editorial on it this morning:

Valentine’s Day quake a severe blow to morale

It began with a rumble and a shudder, then hit with the disorienting, distressing, and disabling force that only a magnitude 5.7 earthquake can.

Many of us dived for cover, a few in a state of panic raced for building exits. Some froze to the spot, tears rolling down our cheeks.

It is likely that the most significant damage to our city will be unseen. The damage to our psychological health.

And this will be ongoing, with fears and frayed nerves resuming.

GNS scientists have calculated the probability of another quake of magnitude-5 or greater striking within the next week at 25 per cent.

It’s unlikely to be worse than yesterday’s quake but any felt shaking will perpetuate anxieties.

For our city was already far from recovered.

In May last year, Canterbury doctors said the city’s mental health – once on a par with most other districts – was approaching crisis. Emergency mental health cases had risen by more than one-third. The number of children and teenagers needing psychological help had leapt two-thirds.

While some continued to suffer symptoms of post-traumatic stress, the more widespread impact of the quakes was on rates of anxiety, depression and substance abuse.

I hope that support and mental health resources are reviewed and improved.

It’s easy for the rest of us to forget how devastating the Christchurch earthquakes have been not just on land and buildings but also on people and their lives.

This is a reminder of the worst kind for those living in and around Christchurch.

Tsunami blip here

There’s been minor signs of tsunami from the Chilean earthquake, nothing to worry about here but worth being cautious about.

It’s amazing that we get any sign of an earthquake from the far side of the Pacific Ocean, over 9,000 kilometres away.

Fortunately there seem to have been relatively low casualties in Chile (currently reported at 10 deaths) from the massive 8.3 earthquake, although a million people were evacuated to higher ground. As reports come out there appears to have been significant damage.

It always takes a day or two for a realistic picture of an earthquake like this to emerge.

Stuff has video and image coverage: Clean-up begins in Chile as earthquake death toll rises

This shows how seismically active our planet is (>4.5 over the last 7 days):

Earthquakes17Sep15is:

Dunedin earthquakes

I was woken up by a bit of a rumble on Monday night, it turned out to be a shallow 4.7 earthquake centred about 30 km west of Dunedin. We don’t get many local earthquakes and Dunedin is rated one of the lowest risk parts of New Zealand.

Usually if we get a shake it has come from further afield. We felt a few from Christchurch over the last few years, got enough of the recent Wanaka shake to feel it, and sometimes we share remnants of a Fiordland shake as well.

There have been a few minor shakes centred in the vicinity of  Dunedin over the years, with the largest recorded earthquake of 4.9 in 1974. That was centred offshore about 10 km south of St Clair. Since then there have been another eight 4.x quakes, several centred similar to the 1974 quake and another cluster to the west where Monday’s was.

DunedinEarthquakes

Quake map from Geonet with magnitudes and dates added

That’s a low number of moderately sized quakes when compared to many other parts of New Zealand.

Om Monday’s quake:

Overnight quake shakes up Dunedin

The earthquake’s location was very close to a magnitude 4.0 quake last October. Last night’s quake is highlighted on the map shown on the right, with last October’s epicentre the other circle close by. As quakes in this part of New Zealand are uncommon, we wrote up a history of earthquakes that have affected Dunedin in the past.

Geonet’s write-up last year –  Dunedin’s shaky past?

Last night, Dunedin and the surrounding area got its first magnitude 4 earthquake in a long time. The M4.1 was widely felt throughout the Otago region, with more than 1,300 felt reports received by GeoNet. This earthquake may have been a bit of a surprise to some people as earthquakes simply aren’t that common in this part of the South Island.

But these have happened before. We dug through our earthquake files to find out more about Dunedin’s shaky past.

Q. How long ago was the last earthquake in Dunedin?

A. In 1991, a 4.1 struck off the south coast of Dunedin, near an area that had previously experienced a few Magnitude  4 earthquakes.

Q. What was the largest earthquake since 1960 in the Dunedin area?

A. The largest earthquake to occur in the area since 1960 was a 4.9 in 1974, which occurred in a similar area to the 1991 earthquake (see below).

Q. Have we had earthquakes in the same area as last night’s?

A. The earthquake that occurred last night (16 October 2014) was very similar to one that occurred in 1982; it was in almost the same location and depth.

Monday night’s quake was a similar depth and in virtually the same place as last year’s quake.

Dunedin is a quaint wee city and compared to more active parts of New Zealand the area has a quaint wee earthquake record.

By the time I woke up and realised that it was an earthquake on Monday night it was all over. I felt the two big ones from Christchurch (7.1 in 2010 and 6.3 in 2011) and they felt stronger, longer and were much more disconcerting.

Earthquakes can be fascinating but also quite worrying. We get a few wobbles in Dunedin but the worries and risks are much bigger elsewhere in the Shaky Isles.

One of the safest places in New Zealand

Dunedin is one of the safest places in New Zealand (when it comes to earthquakes, not quite so safe for students susceptible to alcohol induced self harm).

We’ve been getting a few shakes here over the past few years but it’s always been somewhere else that’s been getting the full force of the earth moving beneath us.

NZ Herald has a map of the relative risk zones in Big changes to earthquake strengthening rules.