7.0 earthquake hits Christchurch, New Zealand

[Astronuc]

When you say things like "ostensibly extinct", you give me agita!

Kidding aside, thanks for an excellent explanation, and... liquifaction is not something you can defend against AFAIK. You can put a building on rockers or springs. make it bend like a willow, but if the foundation goes... game over. You may be able to prevent catastrophic collapse (NZ versus Haiti), but the structure will still need to be destroyed and rebuilt.

The hazard maps apparently did not predict the peak accelerations up to 2.2g, and certainly not in the Christchurch area. What happened was unexpected. I think seismologists didn't expect something like 6 or above just SE of Christchurch.

The experts will have to revise their understanding of the dynamics.

The liquefaction has to do with the water in the soil under Christchurch which sits between two rivers beside a bay, and has at least one stream running through it, and the fact that the earthquakes were so strong.

I feel terrible for (and I say this affectionately) all Kiwis, feathered and mammalian. NZ seems like such a peaceful and welcoming place...

It's going to be difficult for a lot of folks for quite some time. An article in the Herald indicated that some might leave the area or the country permanently.

 

[Astronuc]

Astronuc,

That was absolutely horrifying to watch, I only could watch about 2/3rds of the first video, at about 1:30 or so a woman in a black dress with head injuries was being led away. I found out later she lost her brother who was sitting in a car next to her, he pushed her away and saved her life. The video news story was so sad. it all seems so surreal.

Rhody...

There's many heartbreaking stories, but some good ones too.

Ahsei "Ace" Sopoaga tried to save the brother of that woman.
http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10709041

The brother who saved his sister was Jaime Gilbert.
http://www.3news.co.nz/Young-father...ister/tabid/309/articleID/199985/Default.aspx

And this story
http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10709040

 

[nismaratwork]

The hazard maps apparently did not predict the peak accelerations up to 2.2g, and certainly not in the Christchurch area. What happened was unexpected. I think seismologists didn't expect something like 6 or above just SE of Christchurch.

The experts will have to revise their understanding of the dynamics.

The liquefaction has to do with the water in the soil under Christchurch which sits between two rivers beside a bay, and has at least one stream running through it, and the fact that the earthquakes were so strong.

It's going to be difficult for a lot of folks for quite some time. An article in the Herald indicated that some might leave the area or the country permanently.

Thank you for this information, and the links... I really can only say... I'm so sorry for the people of NZ.

 

[Dadface]

Stay strong apeiron, and again... I'm really glad that you and dadface are alive and whole, with families in similar condition.

Thanks people for sending your good wishes.Just to clarify something it is one of my sons and his family who live in Christchurch,I live in the UK.
In their area they had a lot of mud rising due to liquefaction but they are gradually getting the place cleaned up.I think one of the biggest problems is the anxiety caused by the continuing aftershocks.Many people are finding it difficult to get a good nights sleep.Whilst the clear up continues my grand children have been sent to stay with their Kiwi grandmother in Hokitika on the west coast.She runs a pub so things are not all bad.

 

[nismaratwork]

Thanks people for sending your good wishes.Just to clarify something it is one of my sons and his family who live in Christchurch,I live in the UK.
In their area they had a lot of mud rising due to liquefaction but they are gradually getting the place cleaned up.I think one of the biggest problems is the anxiety caused by the continuing aftershocks.Many people are finding it difficult to get a good nights sleep.Whilst the clear up continues my grand children have been sent to stay with their Kiwi grandmother in Hokitika on the west coast.She runs a pub so things are not all bad.

Wow, I'm glad your sons and families are safe; defiitely time to bite the neck off a bottle!

 

[Astronuc]

Rolling boulders from a hill

http://www.nzherald.co.nz/nz/news/video.cfm?c_id=1&gal_objectid=10709223&gallery_id=117013

These folk have remarkable sense of humor. Luckily no one was killed, although one man was killed elsewhere when debris fell on him while helping another person.


Another site tracking the quakes - http://quake.crowe.co.nz/

 

[apeiron]

Spent most of the day touring quake-struck bits of town and at grassroots reconstruction meetings.

Current repair bill for the two quakes is said to be NZ$20b, of which about NZ$12b is covered by international reinsurance . We have a somewhat unique scheme for national disaster insurance here.

On the zipper hypothesis, it seems the first quake was actually four smaller faults that connected up. And this one is not directly connected. So fits a story where the region is riddled with smallish mag 5 and 6 faults. Over a 100,000 years, they would probably become aligned to make a longer big one (of which there are at least a half dozen known further north).

I was in the roughest part of town (our nearest to a ghetto) for much of the morning, and there was a party atmosphere with church sausage sizzles, more bread and fruit than anyone could eat. There is certainly some burglaries going on, but no big deal.

Again the place has to be given an A+ for resilience. There are search and rescue teams from a dozen other countries and they all say it is the best organised operation they have ever seen (well, September 4 did give us plenty of practice of course).

Yet still, a huge and long effort ahead to get back to normal. No illusions there.

 

[nismaratwork]

Spent most of the day touring quake-struck bits of town and at grassroots reconstruction meetings.

Current repair bill for the two quakes is said to be NZ$20b, of which about NZ$12b is covered by international reinsurance . We have a somewhat unique scheme for national disaster insurance here.

On the zipper hypothesis, it seems the first quake was actually four smaller faults that connected up. And this one is not directly connected. So fits a story where the region is riddled with smallish mag 5 and 6 faults. Over a 100,000 years, they would probably become aligned to make a longer big one (of which there are at least a half dozen known further north).

I was in the roughest part of town (our nearest to a ghetto) for much of the morning, and there was a party atmosphere with church sausage sizzles, more bread and fruit than anyone could eat. There is certainly some burglaries going on, but no big deal.

Again the place has to be given an A+ for resilience. There are search and rescue teams from a dozen other countries and they all say it is the best organised operation they have ever seen (well, September 4 did give us plenty of practice of course).

Yet still, a huge and long effort ahead to get back to normal. No illusions there.

No illusions... maybe that's why you plan so well.

 

[Astronuc]

Aftershocks are still continuing. There was a mag 4.8 near the coast under Sumner.

Recovery operations continue and planning for rebuilding is contingent upon understanding the risk for similar or stronger quakes.

Some discussions:

http://www.asce.org/Disaster-Preparedness-and-Response/Biggs-New-Zealand-Earthquake-Diary.aspx

the Feb. 22 aftershock was twice the design level earthquake. Given that, there is no surprise there were failures! The public response is, why didn't officials demand demolition or full strengthening? Officials did what was historically correct, but this aftershock did not follow the pattern.

This is often the case.

Darfield Quake - http://db.nzsee.org.nz:8080/web/lfe-darfield-2010/home

Christchurch/Lyttelton Quake - http://db.nzsee.org.nz:8080/en/web/chch_2011/home

 

[apeiron]

The Christchurch experience shows what could happen in a lot of places. Here is Portland sounding worried.

http://www.oregonlive.com/environment/index.ssf/2011/02/comparing_portlands_quake_risk.html

Geologists have located three shallow faults that cut beneath the most populated parts of Portland. The largest, the Portland Hills Fault, may pose the greatest risk. It stretches from Oregon City to Scappoose. Corvallis and Seattle also straddle active crustal faults.

Yeats says New Zealand has some of the most progressive building codes in the world and is better prepared for earthquakes than most U.S. cities. Schools in Christchurch appear to have stood up well. Many Oregon schools would not. More than half are at a high risk of collapse from a quake, according to a 2007 report by the Oregon Department of Geology and Mineral Industries.

And then...

Disaster preparedness in Oregon has largely focused on a different kind of earthquakes: those from the collision of massive sections of the Earth's crust, called tectonic plates. From Northern California to British Columbia, an ocean-spanning slab called the Juan de Fuca Plate is plunging beneath the North American plate. In a complete rupture across this Cascadia subduction zone, geologists expect magnitude-9 ground-shaking to persist for several minutes across much of Oregon and Washington. They rupture about once every 450 years.

 

[nismaratwork]

The Christchurch experience shows what could happen in a lot of places. Here is Portland sounding worried.

http://www.oregonlive.com/environment/index.ssf/2011/02/comparing_portlands_quake_risk.html



And then...

Damn it!


Why are some of the best places to live so seismically unstable?? I love Oregon... especially Portland... and hazelnuts... and Tilamook cheddar...

 

[Astronuc]

Christchurch areas to be abandoned
http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10710770

Many places along the Pacific coast are in danger of earthquakes or tsunamis, and in some cases volcanoes. The coast is a nice place to live if one likes the ocean and beaches, but it comes with risk.

There is a particular feature near Fiji/Tonga that if it thruts up or down could cause a significant tsunami that would devastate many coastal cities from Australia, NZ and Chile, up to Japan, Russia, Alaska, Canada and the US.

 

[nismaratwork]

Christchurch areas to be abandoned
http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10710770

Many places along the Pacific coast are in danger of earthquakes or tsunamis, and in some cases volcanoes. The coast is a nice place to live if one likes the ocean and beaches, but it comes with risk.

There is a particular feature near Fiji/Tonga that if it thruts up or down could cause a significant tsunami that would devastate many coastal cities from Australia, NZ and Chile, up to Japan, Russia, Alaska, Canada and the US.

Excellent! I'll be sure to lavishly wet myself every time I make landfall in those regions.

 

[rhody]

Apeiron, Astro, nismara,

You have to check this out: from: http://www.isgtw.org/visualization/visualizing-vectors" ...

This new seismic simulation tool is really, really cool, I will add a few key phrases:

• procedural dipole textured
• intuitive ground swell motion
• wave amplification
• display of flow like nature of seismic waves

There are other applications for this technology as well, Astrophysics...

Click the embedded video...

I think you will be impressed, I know I was.

Rhody...

 

[Astronuc]

I will have to navigate that later.

Meanwhile - http://www.isgtw.org/feature/feature-sixty-seconds-save-city

It seems that the Canterbury plains will be active for some time.

 

[nismaratwork]

Apeiron, Astro, nismara,

You have to check this out: from: http://www.isgtw.org/visualization/visualizing-vectors" ...

This new seismic simulation tool is really, really cool, I will add a few key phrases:

• procedural dipole textured
• intuitive ground swell motion
• wave amplification
• display of flow like nature of seismic waves

There are other applications for this technology as well, Astrophysics...

Click the embedded video...

I think you will be impressed, I know I was.

Rhody...

Now that is just amazing...

@Astronuc: Now that is just depressing as hell, *string of curses in Russian and English*

 

[rhody]

I will have to navigate that later.

Meanwhile - http://www.isgtw.org/feature/feature-sixty-seconds-save-city

It seems that the Canterbury plains will be active for some time.

Astro,

Their response, quite smart...

To provide an early warning, about 100 earthquake sensor stations dot the island. But accumulating data from all of them and then assessing the information takes time. So, a more nimble method was introduced a few years ago, based on gathering data in so-called “virtual sub-nets” — groups of sensors spanning regions of 50km or so. If these sensors confirm a major quake, they can sound the alarm right away, without having to verify what the rest of the entire network has detected.

For quakes which originate in the south and east of the island — the most active areas — this deceptively simple strategy triples the warning time for metropolitan Taipei, from 20 seconds to nearly 60 seconds.

and

So it’s simply not viable to shut down power plants and stop trains every time a tremor is detected. What is needed is a quick prediction of the impact that a particular quake may have on key infrastructures across the island.

But the amount of shaking that an earthquake can produce a hundred or so kilometers from its point of origin can vary strongly, depending upon, for example, the depth at which it occurs.

There is certainly no time to do a full simulation once the first hint of an earthquake is detected. However, according to Li Zhao of the Institute of Earth Sciences at Academia Sinica, it is possible to pull out a pre-processed simulation from a database and make a quick decision based on what it predicts. This requires processing and storing the results of simulations for a huge number of possible quake epicenters, a task well-suited to grids.

Pretty advanced thinking, I must say...

Rhody...

 

[rhody]

Wow, just woke up to http://online.wsj.com/article/BT-CO-20110311-704208.html" news...

TOKYO (Dow Jones)--A massive 8.9-magnitude earthquake struck Japan Friday, causing untold death and damage to the northeast and panic as far south as Tokyo, with an ensuing tsunami devastating coastal areas in the north.

An early death toll in Japan's worst quake was 23, broadcaster NHK said, but the number was sure to rise as communications were cut off to some of the worst-hit areas in the north and helicopter footage showed tsunami waters racing across rice fields, dragging houses and vehicles in their wake.

The quake hit at 0546 GMT and originally was reported at a magnitude of 7.9, but later was upgraded to 8.9. That makes it the fifth largest recorded worldwide since 1900, according to the U.S. Geological Service.

It is far larger than the 7.9-magnitude Great Kanto Earthquake that devastated Tokyo in 1923, killing 143,000, or the 6.8-magnitude quake that hit Kobe in 1995, killing 5,502.

and

A tsunami measured at anywhere from one meter to 7.3 meters hit at various places along the coast, while a 10-meter tsunami was seen at the port in Sendai, near the epicenter, Kyodo reported.

A tsunami warning extended to at least 50 nations and territories, including the U.S. West Coast and parts of South America, and evacuations were ordered in Hawaii.

A Meteorological Agency official appeared on TV urging those affected by the quake not to return home because of possible tsunamis.

"In some areas we have issued a warning of tsunamis of higher than 10 meters and we expect these areas will experience the high water levels soon," said the official. "Please stay on high alert."

http://news.google.com/news/search?aq=f&pz=1&cf=all&ned=us&hl=en&q=massive+earthquake".

http://edition.cnn.com/2011/WORLD/asiapcf/03/11/japan.quake/?hpt=T2"

Rhody...

P.S. I knew it was serious when an alert was splashed at the bottom of the google home page... They hardly ever do that. Let's hope it was not near the surface like the one in New Zealand. They are recommending everyone get 1/2 mile up the coast in Hawaii, waves are expected to arrive (from news) 8 am EST. Someone, please wake up Garrett please... The news is saying they are sounding tsunami alarms in Hawaii. Thank God...

Look at the picture (thumbnail) I just added, that is a 4 story building in the hook of the wave. OMG...

 

[StevieTNZ]

Another aftershock less than an hour ago, reported as 5.5magnitude.

http://nz.news.yahoo.com/a/-/top-stories/9629693/significant-aftershock-rocks-christchurch/

"The latest aftershock to hit Christchurch has apparently caused a building to collapse."
- http://nz.news.yahoo.com/a/-/top-stories/9629954

 

[StevieTNZ]

And another aftershock half an hour ago @ 2.30pm - 6.0 magnitude. 2.40pm - 4.9magnitude.

http://nz.news.yahoo.com/a/-/top-stories/9630497

 

[lisab]

So far no reports of deaths, thankfully. Hang on, Kiwis!

 

[apeiron]

So far no reports of deaths, thankfully. Hang on, Kiwis!

Yes, no deaths reported, some injuries, some more building collapses, some hillsides gone and lots more liquefaction.

The 6.0 said to be 8 on Mercali scale compared to the Feb 22 6.3 which was a 9. This one happened just out to sea where the fault is now know to extend a little distance.

Already in the quakes, about third of the city has been badly affected by liquefaction (Christchurch was built on old swamp) and half the buildings in the central business district are finished. The ground had already sunk by about a metre in riverside areas so that perhaps 10k homes will have to be moved to new ground.

We know now that the region is laced with M6 and M7 faults. But even so, the quake risk for Christchurch going forward is still less than, for example, our capital Wellington. Or Tokyo, Portland, and many other cities.

The experience of other cities also suggests that the rebuilt Christchurch will be much improved (it already ranked high on the scale). So check back in 10 years time.

 

[Astronuc]

http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10731968

Last Monday, there was a 5.5 mag, and now the mag 5.5 and 6 quakes.
http://quake.crowe.co.nz/

Ouch - http://www.nzherald.co.nz/nz/news/image.cfm?c_id=1&gal_cid=1&gallery_id=119463#7713060 - used to be a great view from the living room.

There seems to be quite a bit of activity along the W. Pacific from NZ to the Kuriles. The swarm near Fukushima continues with several mag 5+ quakes. A mild swarm started up in Papua New Guinea.

There is some activity on the eastern side of the Pacific from S. Mexico to Panama.

And there is some rare activity in Eritrea-Ethiopia area.

 

[apeiron]

Yesterday's shakes have been upgraded in strength...

The largest earthquake has been upgraded to magnitude 6.3, with a shallower depth of 6km. The 2.20pm quake was originally analysed as 6.0 in magnitude at a depth of 9km.

The 1.01pm tremor has also been upgraded [from 5] to 5.7, and was at a depth of 10km - not 11km - new GNS figures show.

Haven't worked out whether that is good or bad news yet .

 

[Astronuc]

Thre was mag 5.4 on 21-Jun 10:34pm at a depth of 8.28 km. It is rated Mercalli VI with an energy release equivalent to ~2 kilo tonnes.

http://quake.crowe.co.nz/QuakeEnergy/

Quake hit homes: details tomorrow
http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10733711

Some folks will have to abandon their homes.

The seismic activity has changed around Christchurch since Sept 4, 2010.

 

[apeiron]

The financial impact of the quakes is also impressive. The current bill is 8 percent of national GDP, compared to 2 percent for the recent Japanese tsunami/meltdown event and 1 percent for Hurricane Katrina.

But NZ is also unusually well-insured for these events and Christchurch will enjoy eventually the dividend of a massive rebuild operation (economy will be booming even if the place is a city-size building site).

 

[Astronuc]

The financial impact of the quakes is also impressive. The current bill is 8 percent of national GDP, compared to 2 percent for the recent Japanese tsunami/meltdown event and 1 percent for Hurricane Katrina.

But NZ is also unusually well-insured for these events and Christchurch will enjoy eventually the dividend of a massive rebuild operation (economy will be booming even if the place is a city-size building site).

I wonder how and where the rebuilding will occur. The seismic hazard potential has changed considerably around Christchurch and the Canterbury Plains. The question to be pondering is, "What has changed and for how long?"

The fault system from Darfield to Sumner and off the coast has become much more active, and demonstrates the potential for mag 6+ quakes.

Note the substantial change in frequency and magnitude of quakes since Sept 4, 2010. The figure shows earthquake magnitude as a function of date+time from beginning of 2007 to through June 21, 2011.

 

[apeiron]

I wonder how and where the rebuilding will occur.

There was a first big announcement yesterday. A lot of land around the Avon River has sunk below sea level so some 5000 households will be paid out by government and move to new subdivisions. Another 5000 are likely to follow (out of a town of some 120,000 homes).

The central city has lost half its shops, hotels and office buildings at least. The rebuild plan should be decided by Xmas (safely after our next general election).

As to seismic activity, this is now being treated as an ongoing event . There is a chain reaction going on because the land is filled with smallish (up to mag 7) faultlines. Originally it was thought the tensions would play themselves out in months, now it looks like years.

This is new science as it is the first time this kind of fault structure has been so intensely followed. Most seismology is based on the main continental plate faults (like our Alpine fault). The Christchurch stuff has been the disturbance of an area off to the side which might only switch on every 50,000 years or more.

It could have happened in many other places in the world with a similar geology. Portland I have mentioned. And something like it happened off the San Andreas in the 90s, but I think out towards the desert where no one much cared.

So this is a kind of event that is more unpredictable it seems because human civilisation is recent enough it hasn't hit a sizeable city before (and one a third build on liquefaction prone swamps, and the hillsides of the rocky rim of a big volcano).

At least the volcano here is definitely extinct.

 

[Astronuc]

Sometimes extinct volcanos come back to life, or they get new neighbors.

Something has decidedly change in near Christchurch. Think about the consequences of a new magma bubble/chamber rising under Christchurch. I hope someone is looking at changes in gravity and local magnetic field.

The western Pacific Ring of Fire has become more active since I've been watching for the last 6 years.

Don't bet on an extinct volcano remaining extinct.

Interestingly, the Eritrea volcano Nabro apparently has no recorded history of eruption! It is first recorded (witnessed by humans) eruption of that volcano.
http://www.irishweatheronline.com/news/earthquakesvolcanos/first-footage-emerges-of-eritrean-volcanic-eruption/21037.html

 

[apeiron]

Don't bet on an extinct volcano remaining extinct.

NZ at least has some of the world's most competent vulcanologists. The place is covered in instruments. It is quite certain that the nearest magma bubble is under Lake Taupo. Other places are going to blow first.