Tuesday, 31 May 2011

Christchurch Quake Warnings extended by GNS Science

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Prior blog entries this year, on Christchurch, like this one and Recent Quake Data, give some background of my concern over the future of Christchurch as a safe, viable place to live. These concerns involve not only the geophysical state of the local region and city, but also the disturbed people energy, which spreads and reproduces.

A regular tracking of the daily aftershocks through the Christchurch Quake Map (2640 aftershocks plus the initial event on Feb 22, (7068 from Sept 4 2010 to May 31) shows how regularly the area is pummeled, from central Christchurch, west to the Greendale fault which occurred last September, and east to the harbour hills as well as the seafloor.

Challenging social issues will continue to hit the headlines despite the highly commendable efforts of many who wish to rebuild their lives and communities. Their lives will never be the same as pre-quake and their strong attachment to their beloved neighbourhoods may test them to the extreme.

Today, NZ Herald reports that the government science agency GNS has now taken a rare, proactive stance, in forewarning of the likelihood of a high intensity quake in the region, in the coming 12 month period. The probability percentage has been raised significantly from an earlier forecast, only a month ago.
Furthermore the risk zone is delineated as region-wide, from Rangiora in the North to Lincoln in the South, west to Sheffield, east to Banks Peninsula.    full report (Update: the original text has been edited on the Herald website and information deleted re upgraded forecasting, that was visible this morning. This is highly questionable and raises the question of who ordered the removal and why.)

For a government science office to release this type of probability forecasting, there would be clear grounds to assume a seismically significant event is on the horizon.

This report places the people of Canterbury region and the Christchurch City rebuild in virtual suspension.

Where to now?

The citizens must be fully informed.



Update pm May 31

Contact hazards modeller Dr Matthew Gerstenberger at the Crown research institute to see if he can confirm the very recent reformulated predictions updated just in the past month. Being a government employee however, he may now be subjected to a gagging order. (oops even he is back-tracking now since the story burst: "We don't really have any specific way to narrow that down to Christchurch, but as a kind of guide based on some basic information, that's roughly a quarter of that probability." -via TVNZ website.   Ehhh??
After all, it was only Councillor Sue Wells blog that gave the media a release on this. It is seeming now like she let a rather large cat out of the bag.
Meanwhile Mayor Bob Parker is in damage control mode, somehow translating the science into a new probability %, a probability based on a probability and the estimated unlikelihood of history repeating...He is on shaky ground here.
GNS say Scientists are still investigating why this has been a particularly rich sequence compared with the forecasts on the Geonet website, but neither GNS not Geonet appear to have published a press release on their sites re the information released by Sue Wells.

The Christchurch Press of today  has some interesting feedback on this story.

3News featured the story on TV3 May 31st, but Recovery Minister Brownlee undermined the science saying "It's just a prediction." likening it to the Rapture date prediction by Harold Camping. Ehhh???

Update June 1
Sue Wells on Afternoons with Uncle Jim says she received vitriolic feedback for writing of the seismic forecast. The reaction she got is akin to some of the flak directed at alternative forecaster Ken Ring. The negative response shows a lot of people are too afraid to think ahead. The rest of us are too afraid not to.

Public have the right to know says local MP Brendon Burns in the Press today . The Christchurch Press has a feature section covering quake matters and it is well worth referring to ( access via prior link)

Update June 2
The Press reports a storm has erupted over this issue, resulting in a press conference to be called on Friday June 3, allowing further clarification by geoscientists.

Update June 3
The Herald reports more unknown faults located.
The Press prints what they wish to release of this story.
View the GNS maps particularly the cluster of seafloor active faults & newly discovered Pegasus Bay active fault, opposite Kaiapoi

Aftershock frequency in Canterbury has dropped dramatically in the past week - down to only 2 on days in past week.
Update June 4
South of Rolleston, in a rural setting, a M4.1 this morning, 7kms deep, 11.07 a.m.
Update June 6
South of Rolleston, in a rural setting, a M5.5 this morning, 15kms deep, 9.09a.m.
refer to GEONET data
The Christchurch Quakemap data by 7.04 pm shows the region surrounding Rolleston, south-west of Christchurch, has been hammered by 12 of the 15 quakes so far today. Today's activity contrasts with recent subsidence, with the past week featuring since May 31 the following daily totals of aftershocks in the local region: 4,2,2,2,3,3
The final total was 24 shocks on June 6, most around Rolleston, 10 events M3.0 and higher. see Quakemap
Update June 7
Today's aftershocks (total 10 by 8.21 pm) mainly around Rolleston, all small, shallow events.
The Daily Energy Release graph is also worth a look

Update June 8
In the Press, a geoscientist basically fails to assure anyone : Dr Kelvin Berryman says we're always going to do ballpark figures and that  scientists are failing to communicate scientific data to the public.
Is there a geoscientist who will stand up and say:
The situation in Canterbury-Christchurch is unusual, unexpected and therefore highly unpredictable. On that basis people must clearly choose whether to stay or go, as a significant risk cannot be dismissed as unlikely. Neither the government, local or national, nor the support services can protect you from any future event and given the financial burden related to recent quake events, the likelihood of continued financial bailouts, in response to a further major natural disaster, is conversely of low probability.

An overseas report (audio) re early quake prediction concerning infra-red emissions and electron concentrations in the atmosphere and ionosphere, possibly triggered by radon gas emissions from the earth.

Update June 11
The region surrounding the Greendale fault in west Canterbury (site of the Sept 4 quake) is being hammered by small shallow aftershocks. Nearby Rolleston came into the picture with a M4 on May 9, so  this has resumed being an active area for the past month, peaking on June 6 M5.5.

Since ground level changes post-quakes have meant a sinking of up to one metre in some areas, Christchurch is warned about sea level rise by global warming scientist James Hansen. His views are disputed by a New Zealand scientist. Meanwhile Kiwi grandad Nigel Williams (formerly of Christchurch) is concerned about melting sea ice making NZ coastal communities uninhabitable. He provides google sourced maps to show even an 80 metre inundation is significant all over NZ. This is a longer time frame scenario in all cases but if Christchurch is geologically moving to a sinking pattern, aggravated by quakes, heavy rainfall events will continue to increase flood risks. In addition, the Pegasus Bay faults noted in the June 3 update could feasibly be the site of an offshore quake, producing a tsunami wave. Rangiora and Kaiapoi would be in the central gathering point of a water force from the bay.



Update June 12
A data diary of Chch aftershocks compiled by TVNZ
Christchurch Airport is the main one affected in NZ by volcanic ash from Chile

Update June 13
Significant quake events of today in Christchurch are outlined in a new post with detailed info.

Update June 15 
New probability figure released: according to the Christchurch Press report of this morning:
New calculations by GNS Science yesterday show that from today until June 15 next year there is now a 30 per cent chance of a quake of between magnitude 6.0 and 6.9 striking the Canterbury aftershock zone.

Banks Peninsula is being hammered, up to M5.0, continuing an apparent eastwards trend towards the seafloor, the northern coastal hills feature strongly in the data to 8.30a.m. today. Banks Peninsula is an interesting volcanic zone, the most prominent in the South Island. There is a fractured history of Maori-Paheka discord prior to the Treaty in 1840.

Update Sept 6
Having reached the anniversary of the Sept 4 2010 M7.1 quake, a lot of analysis has gone on.
This summary is useful, with a geoscientist's future predictions
Notable quake activity (M4+) resumed after a lull in early August and some GNS predictions are being exceeded in the current 4 week survey 




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