http://canterbury.royalcommission.govt.nz/

There are also many technical reports available on this website, written by EERI members and colleagues. These technical reports discuss various structural and geotechnical engineering issues.

Please click here to read more.

http://www.stuff.co.nz/the-press/news/christchurch-earthquake-2011/5427734/Plan-to-build-a-city-in-a-garden

The draft plan can be viewed online at the end of the article. The plan document can also be downloaded from the following link: http://static2.stuff.co.nz/files/ChristchurchCityCouncilDraftCentralCityPlan.pdf

TOC – Draft Central City Plan

The Big Picture
Introduction
Past Present Future
Remembering/Maumaharatia
Distinctive City
City Life
Transport Choice
Market City
Transitional City
Implementation

Simple by design, the mapper streamlines the GEO-CAN image analysis process. To participate, visit http://tomnod.com/geocan/?source=eeri. You will be able to search for, label, and quantify damage in buildings and areas of liquefaction. Each participant adds a small piece to the complete picture, resulting in a crowd-sourced solution that is obtained quickly, accurately, and easily through the web-based portal. The mapper leverages existing commercial cloud infrastructure to manage massive datasets and corresponding metadata with structured, searchable databases.

The platform includes training examples of the various damage states specific to the Christchurch event. You can take the tutorial, and once completed, sign up. You will be assigned a grid. Multiple people will be assigned to the same grids, so that comparisons can be made about the accuracy of the analyses. This professional development opportunity will improve your skills in remote sensing analysis and will help determine the potential of high-resolution aerial imagery and the technology’s future applications in damage assessment.

In addition, geotechnical engineers will be contacted to participate in a liquefaction study. Remote sensing experts will be invited to analyze satellite imagery (as opposed to the high-resolution aerial imagery) to determine differences in the assessments. If you would be interested in participating, contact Marjorie Greene at mgreene@eeri.org.

4 Weeks on : Preliminary Reconnaissance REPORT FROM THE CHRISTCHURCH 22 Feb 2011 6.3M_w Earthquake

Weng Y Kam[1] , Umut Akguzel[2] , Stefano Pampanin[3]

Download the full report (with figures) here.
**re-posted from the NZSEE Clearinghouse website.

1         Introduction

1.1      Note

This informal report provides an updated view of the various aspects in relation to the 22^nd Feb 2011 6.3 M_w Christchurch earthquake event, 4 weeks after (written on the 25^th March 2011). This is a preliminary report subjected to changes/amendments as new information is gathered.

1.2      General and services recovery (as of 15^th Mar 2011)

The state of national emergency has been extended for the 5^th time on the 31^th Mar 2011, covering the territory of Christchurch City Council. Further information of the New Zealand’s National Civil Defence Emergency Management Plan [1, 2]is available at: http://www.civildefence.govt.nz/

110 of the 163 elementary and secondary (high) schools have reopened by the 14^th of March 2011, with some schools reopened since the start of Week 2 (7^th March).  

Water has been restored to 94 percent of households. 99.7 per cent of the city overall had power, with only 550 properties outside of the CBD still without power. Electricity was still off to around 50 percent of the CBD. Sewerage services are still compromised in many Eastern suburbs, with portaloos and chemical toilets being distributed as alternatives.

The bus services have been partially restored with two temporary bus terminus set up at the Hospital (Parkside) and the Bealey Avenue. 21 non-operational and 35 operational routes.

2    CBD Earthquake Records Acceleration Response Spectra

The elastic response spectra (5%-damped) from four recorded ground motions (of both the principal and secondary horizontal motions) from the Christchurch CBD are compared with the site seismic design coefficient in Figure 1. The NZS1170:5 [3]500-years and 2500-years design spectra for Christchurch site (Z/PGA=0.22g), distance R = 10km and soil class D (consistent with the four recording sites) is also plotted in Figure 1.

[IMAGE LINK] Figure 1: 5%-damped elastic acceleration response spectra in the Christchurch CBD and the NZS1170:5 design spectra (red solid) for Christchurch (soil class D, R=10km): a) Principal horizontal direction; b) Weaker secondary horizontal direction.

Some preliminary observations on the horizontal acceleration response spectra:

1. In general, the shaking in the CBD was exceeding the 500-year motion design spectra, which is the typical ULS design motion in New Zealand.
2. The principal direction of shaking is of the predominantly East-West component. The East-West components are approximately 15-30% higher in the periods ranging from 0-2.4s, except for the period range of 0.35s-0.6s in which the North-South components were stronger.
3. The East-West components matched or exceeded the New Zealand loading standard NZS1170:5[3]2500-year motion 0.5s-1.75s (approximately 5-20 storey RC buildings).
4. In the longer periods, the shaking demands have also exceeded the 500- year motion design spectra.

The equivalent vertical spectra from the NZS1170:5 [3]is plotted in Figure 2with the vertical response spectra from the four CBD recording stations. NZS1170:5 [3]used a multiple factor of 0.7 to determine the vertical spectra from the horizontal design spectra. At the short periods (T<0.3s) however, the vertical spectrum is assumed to be the same as the horizontal spectrum, to account for high-frequency content of vertical motions.

As it is difficult to determine the vertical stiffness of structures, it is hard to correlate the vertical acceleration demand to structural vertical response spectral demand. At very short period range (0.05s < T < 0.25s), the vertical response spectra greatly exceeded the expected 2500-year motion vertical spectra (according to NZS1170:5).

[IMAGE LINK]Figure 2: 5%-damped elastic vertical acceleration response spectra in the Christchurch CBD and the NZS1170:5 design spectra (red solid) for Christchurch (soil class D, R=10km).

3    CBD Earthquake Records DISPLACEMENT Response Spectra

The displacement response spectra give a better representation on the seismic displacement demand on the buildings [4]. The 5%-damped elastic displacement response spectra for the four CBD recording stations are plotted in Figure 3.

Assuming some levels of ductility and post-yield stiffness, effective period, T_eff of a structure can be approximated from the initial period, T_i [4]. For instance, a ductile RC frame building (µ=4, r=0.02), effective period is approximately twice the elastic period.

Some preliminary observations:

1. In the principal direction, there are significant displacement demands between 1.0s to 1.8s and 2.9s to 3.8s. This suggests, in-elastically responding RC buildings between 5 to 10 storey and 15 to 20 storey would have significant displacement demands and by extension possibly significant damage. The principal direction motion is exceeded the NZS1170:5[3]2500-year motion design spectra at these two period ranges.
2. At all period ranges, the principal direction horizontal shaking exerted higher than the 500-year design displacement spectra.
3. The two ‘amplification lumps’ observed in the principal direction motion are not apparent in the secondary horizontal direction motions. In addition, the spectral displacement demands in the secondary direction are significant lower when compared to the principal direction.

[IMAGE LINK] Figure 3: 5%-damped elastic displacement response spectra of four Christchurch CBD records and the NZS1170:5 design spectra (red solid) for Christchurch (soil class D, R=10km): a) Principal direction; and b) Secondary horizontal direction.

4     Civil Defence Emergency Response

4.1    Civil Defence / City Council Building Safety Evaluation Operations

Structural engineers are predominantly engaged with the Civil Defence / City Council Building Safety Evaluation (BSE) operations. Following are some of the ongoing operations that the authors are involved in or aware of:

1. Critical Building Project– This project deals with the assessment and emergency stabilisation, shoring and deconstruction of buildings that are critical to the operation/re-opening of the city center – either critical to the major traffic way or critical in terms of their impacts to the surrounding buildings. At the time of writing, 30 buildings above 6-storeys of various construction age and lateral resisting systems are monitored under this project.

[IMAGE LINK] Figure 4: a) Critical building project team; b) Building evaluation and structural engineers briefing; c) Police vehicle recovery operation within the CBD; and d) 18^th March 2011 Memorial Day.

1. Operation CBD– The Operation CBD involves Level 1 and Level 2 building assessment according to the BSE procedure. The objective is to assess the building soundness for re-occupation or temporary re-entry. The level 1 tri-colour placard tagging was completed for the CBD area apart from three no-go areas around the Grand Chancellor, PGC and CTV buildings on the 5^th Day (27^th Feb 2011. At the time of writing, the Level 2 assessment was approximately 65% completed (verbal information). Figure 5summarises the CBD building tagging statistics as per 27^th Feb, 8^th Mar and 18^th Mar 2011.

[IMAGE LINK] Figure 5: CBD buildings tagging statistics. Note: There are some duplicity of data points due to possible multiple assessments of a properties (with multiple addresses e.g. Apartments). Level 1 and 2 assessments are not discretised.

1. Operation Suburbfocussed on: i) To ensure people are safe and well; and ii) To provide initial assessment of residential homes. Each team includes a building official, an EQC assessor and a welfare representative from either the Red Cross or the Salvation Army. If necessary, structural engineer will be called in to assess the residential buildings.
2. Operation Shopsfocussed on essential commercial (malls, shopping centres, large hardware stores) and medical (clinics and pharmacies) buildings in the city-wide area, was completed on the 25^th March 2011. 10-14 buildings were red-stickered.
3. Operation USAR ‘deconstruction’– Deconstruction operation involves the partial or total deconstruction of the building for rescue or recovery purposes or because it presents an unacceptable safety risk from aftershocks. As per 18^th March 2011, there were 114 buildings within the cordon which required deconstruction. The progress to date is as follow: a) 47 have been completed, b) 24 are in progress; and c) 43 are to be deconstructed.
4. Project demolition– Under the national emergency legislation and the Canterbury Earthquake Emergency Act (2010), buildings that are hazards to public safety and city recovery can be demolished under an accelerated consent protocol.

For non-heritage-listed buildings with six storeys and less, standalone (not connected to adjacent buildings) and built after 1945, may be demolished without a demolition building consent.

For other buildings (six storeys or more, joined to other buildings or built before 1945), a process is in place which would includes structural engineer’s assessment report and demolition plan, peer-review by another independent structural engineer, Christchurch City Council’s review and recommendation, and the final decision by the Civil Defence National Controller on whether or not the building can be demolished. This process can override existing heritage law.

1. Project CSR (Customer Service Request)– to inspects suburban residential buildings which are considered a serious threat to people or property, as per reported by neighbouring residents.

4.2    Welfare centres and Recovery Assistance Centres

On the first night (morning of 23^rd Feb), up to 950 people were housed at the Hagley Park and Burnside High emergency welfare centres. Temporary shelters, blankets, food, sanitation are supplied at the centres. By the 4^th day (26^th Feb 2011), three welfare centres housed 329 people. Welfare centers are now all closed by the 2^nd week (11^th March 2011), with the last welfare centre (Pioneer Stadium) being converted into a Recovery Assistance Centre.

Recovery Assistance Centres are one-stop-shops where people can access welfare information and services. They bring together central, local government and non government organisations. In addition, Recovery Information Kiosks have been opened throughout Christchurch. The kiosks are places within communities where people can get information on the help available following the Christchurch Earthquake.

4.3   CBD and business recovery and continuity

Business recovery and continuity is a major issue.

Map of recovery centers, info centers, emergency management centers.  

[IMAGE LINK] Figure 6: a) Cordon reduction zone as per 14^th March 2011; b) Removal of essential business items from damaged buildings within the cordoned Red Zone.

5    CBD Distribution of Damage and State of Recovery

5.1   CBD building damage (BSE tagging) distribution

Table 1and Figure 8presents the statistics of the Building Safety Evaluation of the CBD buildings, as per 18^th March 2011, divided into different construction types. While the building tagging status is not a direct representative of damage, it is the best-available indicator index

[TABLE LINK] Table 1: Building safety evaluation tagging status for CBD buildings as per 18th March 2011 (Data courtesy of the Civil Defence).

The predominant construction types within the CBD are timber and reinforced concrete constructions. Timber construction is typically used for residential buildings at the fringe of the CBD area. In general, these low-rise timber structures performed very well.

Unreinforced masonry generally performed poorly, with significant number of buildings red-tagged. However, only 289 addresses were assessed to be unreinforced masonry, which is somewhat lower than expected. From field observation, it was understood that many unreinforced masonry buildings did not require a BSE tagging due to the considerable damage and collapse.

The distribution of damage and the high number of ‘red – unsafe’ tagged buildings confirmed the expected high number of damaged structures given the level of shaking intensity.

5.2State of recovery

A major effort to deconstruct dangerous and unsafe structures, as well as to clean up the CBD streets has been on-going. Following is a short pictorial comparison of various heavily damaged section/streets of the CBD – taken at the 2^nd day (23^rd Feb) and three weeks after (14^th Mar).

[IMAGE LINK] Figure 7: Before and after photos of the heavily damaged Manchester-High-Lichfield Streets corner.

[IMAGE LINK] Figure 8: Building safety evaluation tagging status for CBD buildings as per 18^th March 2011.

[IMAGE LINK] Figure 9: Before and after photos of the heavily damaged Manchester-Gloucester streets corner.

[IMAGE LINK] Figure 10: Before and after photos of the heavily damaged Colombo-Kilmore Street corner.

5.3     Urgent stabilisation / deconstruction work

Urgent stabilisation work was carried out either by the USAR operation or by contractors, acting either on behalf of the Civil Defence’s Critical Building Team or the building owners. Following are some notable examples.

[IMAGE LINK] Figure 11: Temporary stabilisation work to restore the axial and shear integrity of heavily damaged basement columns at a multi-storey RC building. The steel encased reinforced concrete improvements confinement and shear capacities of the damaged columns.

 [IMAGE LINK] Figure 12: Concrete encasement for temporary stabilisation of a shear-damaged RC wall of a multi-storey. The photo on the left shows the first phase of the stabilisation. In the 2^nd phase, the RC wall will be completely jacketed to full-height, with sufficient anchorage to the 2^nd floor slab. The left-side photo is courtesy of Ruaumoko Solutions. 

[IMG LINK] Figure 13: A post-tensioned RC foundation slab was erected to provide foundation support for a 2^nd phase propping of the historical Victoria Clock Tower.

[IMAGE LINK] Figure 14: Urgent controlled demolition of the heavily damaged RC infill frames St Elmo Courts, as it was uneconomical and unviable to save the building.

[IMAGE LINK] Figure 15: The historical Old Trust and Loan building and Olympia building was demolished recently in order to clear the collapse hazard along the Hereford Street. The facade walls of both buildings were badly damaged.

6      Reinforced concrete Car park BUILDINGS and vehicle recovery

Since 15^th of March, the police with the Civil Defence USAR operation have been organising a phased vehicle recovery process from car parks within the CBD. Nevertheless, three car park buildings were assessed to be unsafe for the police vehicles recovery process, including the collapsed Smiths City car park, and the damaged 33 Lichfield Street car park and Farmers Oxford Terrace car park. Further information is available here: http://www.police.govt.nz/christchurch-vehicle-recovery.

[IMAGE LINK] Figure 16: Localised collapse of 1^st floor at the Bedford-Lichfield St car park (with many of the vehicles recovered on the 20^th March 2011).

The Smiths City car park had pan-cake collapse at several levels. Punching shear failure of the 220mm thick flat-slab on wide columns (~1200x450mm) can be observed at the South section of the collapsed building. A section of the building over the Dundas Street, consisted of in-situ prestressed RC beams had also pan-cake collapsed. 

[IMAGE LINK] Figure 17: The pancake collapse of the Smiths City Dundas St car park due to punching shear failure of the columns.

7     CONCLUSION

It has been a month since the end of the search and rescue operation (3^th March 2011) and nearly three weeks since the end of the USAR recovery operation (9^th March 2011). The Civil Defence and the Christchurch City Council authorities are focussing the resources towards the recovery of essential services, support of local business (by reopening CBD zones and facilitating entry to condoned area), social and essential welfare support and the transition into the recovery phase (end of the national emergency period).

This very preliminary field report is prepared to provide immediate information for interested parties. However, this is a draft document and will be subjected to future amendments/corrections. Please kindly acknowledged for the use of any photographs. The report above is not peer-reviewed. Please kindly forward your thoughts/comments to me at weng.kam@canterbury.ac.nz.

Authors would like to acknowledge the excellent support provided by the Civil Defence and the Christchurch City Council on the field reconnaissance. In addition, the Civil Defence vision to collate and share of the information and lessons from this nationally and internationally significant earthquake in order to prevent and mitigate future hazards is commendable.

REFERENCES

[1].MCDEM. National Civil Defence Emergency Management Plan. Wellington, NZ: Ministry of Civil Defence & Emergency Management (MCDEM); 2005.

[2].MCDEM. The Guide to the National Civil Defence Emergency Management Plan 2006. 1.2 ed. Wellington, New Zealand: Ministry of Civil Defence & Emergency Management (MCDEM); 2006.

[3].NZS1170. NZS 1170.5:2004 Structural design actions. Wellington, NZ: Standards New Zealand; 2004.

[4] Priestley MJN, Calvi, GM, Kowalsky, MJ. Displacement-based Seismic Design of Structures IUSS Press, Pavia, 2007.

A seismogram at Heathcote Valley, which is located one kilometer from the epicenter, recorded PGA (Peak Ground Acceleration) as high as 1.4 g. However, while no complete collapses were observed, fallen chimneys were widespread. In the hillside town of Lyttleton, about four km away from the epicenter, except for the collapse of old masonry buildings and a few poorly built houses, no major damage was reported.

Fig. 1 Typical chimney failure at Heathcote valley, and most brick veneer seems intact	Fig. 2 Typical settlements in the hills of Lyttleton performed generally well though subjected to large ground shaking

 In Kaiapoi, about 23 km north of epicenter, where peak ground acceleration of 0.2g was recorded, many homeowners reported slight plasterboard cracks and minor foundation cracks because of uneven settlement. One homeowner had spent a good deal of money earlier to repair some minor settlement damage after the September 2010 earthquake, which had caused higher ground motion in the area (PGA of 0.34g), but, unfortunately, the same type of damage reoccurred after this February’s earthquake.

The surveyor on the team found the wood-frame construction in New Zealand is generally well constructed. The superstructure is firmly attached to the foundation through closely spaced anchorage and brick veneer, which is usually very vulnerable to earthquake shaking, has been effectively connected to plywood.

Across Christchurch, which is situated on a very soft and deep alluvial deposit, particularly along the Avon riverbank and in east coastal areas, liquefaction was again the primary cause of severe damage to dwellings. Even within the CBD, liquefaction-related settlement and lateral spreading is quite common. At the intersection of Peterborough Street and Manchester Street, for example, some buildings settled as much as 1 meter, and the soil subsidence buried many cars.

Figure 4. Before Sept. 2010 (Source: Google)	Figure 5. Feb. 23, 2011 (Source: Kam, WY)	Figure 6. March 15, 2011 (Source: AIR)
This apartment settled significantly mostly after the Feb. 2011 earthquake

Figure 7. Cars are likely to be totaled after being buried by liquefaction- ejected sand	Figure 8. Motorists negotiating a section of Fitzgerald Ave passing a dangerous break on the former northbound lane

Liquefaction along the Avon riverbank in eastern Christchurch was very severe. Although damage to houses was hardly perceptible from a distance, the saturated and graveled road along the river revealed the severity of liquefaction damage. The area’s disrupted sewerage service was also the result of liquefaction and it was reported that Christchurch is still without permanent sewarage systems.

Figure 9. Asphalt roads along Avon riverbank and in eastern Christchurch were severely cracked by liquefaction, and most of them will likely have to be rebuilt

At Courtney Drive in Kaiapoi, an entire dwelling was moved backwards about 1.2 meters by last September’s quake, and it was moved rearward another 0.6m by the February earthquake. Another dwelling nearby was ripped open 1.5m by the September rupture, and then pulled apart another 0.05m. The owner, a Japanese native who experienced the 1995 Kobe earthquake, was grateful that her family members were not injured, given that such a large fissure had opened right beside her bedroom.

The woman had decided to rebuild her house with reimbursements from the Earthquake Commission (EQC)  and her private insurer (plus some personal expenditures).  At present, a large portion of residents are living in temporary lodgings, and almost the entire community will have to be demolished and rebuilt. However, how long this will take is not yet known. Many people are concerned that if it takes too long to rebuild the community, many residents may be forced to settle elsewhere.

Figure 10. September 16, 2010	Figure 11. March 15, 2011
The fissure developed another few centimeter after the February 2011 earthquake

Figure 12. September 16, 2010	Figure 13. March 15, 2011
The dwelling drifted more than another half meter after the February 2011 earthquake

 The liquefaction-related damage to Christchurch was not completely new to New Zealanders. In 1996, a documentary (http://www.youtube.com/watch?v=NkTy6ogLDX8) had outlined the effects of a major earthquake in Christchurch’s eastern suburbs. The eight-minute clip reported that Christchurch’s “fatal flaw” was the land that it was situated on – “a soft, shaky sponge of river stones and silt half a kilometer deep.” The report continued, “In any decent quake, the Garden City will shake like a leaf, and liquefaction would cause sewers and drains to come apart, roads to break up and buildings to sink or tip over.”

In summary, because the magnitude of the February earthquake was much smaller than the one last September, its affected area was smaller. However, because the epicenter of the February event was located much closer to the city center and the city’s eastern shoreline , the shaking intensity in the CBD was much stronger and the area of liquefaction damage was wider and also extended to the more affluent Southeast Christchurch community.

While the exact number of dwellings that have been damaged remains unknown, a media outlet citing a government source has reported that about 10,000 homes are likely to be demolished and that some of the area is beyond repair and will have to be abandoned.

Based on this report, it is believed that the total number of damaged dwellings will be slightly lower than that caused by the last September’s earthquake (a total of 160,641 dwelling claims). However, the severity of the overall damage  is higher and would result in higher economic losses. Another significant observation concerns the new damage sustained by previously heavily damaged dwellings. Because the second earthquake followed the first one  in such a short period of time, before reconstruction or demolition had started, the final reconstruction cost will be counted only once. This could mean a significant financial relief for both EQC and private insurers.