Application of the Recommendations
of the Canterbury Earthquakes Royal
Commission to the Design, Construction,
and Evaluation of Buildings and Seismic
Risk Mitigation Policies in the
United States
William T. Holmes,a) M.EERI, Nicolas Luco,b)
Fred Turner,c) M.EERI

M.EERI,

and

An unprecedented level of data concerning building performance in the
Canterbury earthquake sequence of 2010–2011 has been collected by the
Canterbury Earthquake Royal Commission of Inquiry. In addition to data
from a technical investigation undertaken by the New Zealand Department of
Building and Housing on four specific buildings, the Royal Commission has collected data from many other invited reports, international peer reviews of reports,
submitted testimony, and oral testimony and examination at public hearings.
Contained in the Commission’s seven-volume final report are 189 specific
recommendations for improvements in design codes and standards, hazard mitigation policy, post-earthquake building safety and occupancy tagging, and other
topics. Some of these recommendations are unique to New Zealand’s system of
government, engineering practice, or codes and standards, but many are applicable in the United States. [DOI: 10.1193/030613EQS064M]

INTRODUCTION
In response to the Canterbury earthquake sequence that began on 4 September 2010 and
caused significant death and injury on 22 February 2011, the Cabinet of New Zealand established a Royal Commission of Inquiry on 14 March 2011. The Commission was established
to report on the causes of building failure as a result of the earthquakes as well as the legal and
best-practice requirements for buildings in New Zealand Central Business Districts (CERC
2012). The Commission comprised three commissioners, several staff attorneys (Counsel
Assisting), and considerable administrative support provided by the New Zealand Department of Internal Affairs (DIA 2001). The inquiry began in April 2011 and was completed in
November 2012.

a)
b)
c)

Structural Engineer, Rutherford + Chekene, San Francisco, CA
Research Structural Engineer, U.S. Geological Survey, Denver, CO
Staff Structural Engineer, California Seismic Safety Commission, Sacramento, CA
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Six issue areas were initially identified for investigation:
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•
•
•
•
•

Seismicity.
Inquiry into buildings in the Christchurch Central Business District (CBD).
Inquiry into legal and best-practice requirements.
Changes in New Zealand Design Standards/Codes of Practice over time.
Development of technical expertise in the design and construction of earthquakeresistant buildings.
Future measures.

Written advice regarding these issue areas was obtained from people and organizations
within New Zealand who had appropriate expertise, and these submissions were peer
reviewed by eminent overseas experts. The Commission called for expressions of interest
in relation to the issues and, in addition, sought out others who might have pertinent information who did not respond to the original call. Finally, the evidence collected was presented
and discussed in public hearings.
The results of the inquiry are contained in seven volumes that contain 189 specific recommendations. These recommendations obviously have been developed for New Zealand building types, building regulatory framework, and seismic mitigation policies. However, many of
these aspects of building design and construction in the United States and New Zealand are
sufficiently similar to warrant serious consideration of many of the recommendations for
application in the United States.
This paper is intended to identify recommendations that are applicable in the United
States and to group them by subject area, to enable efficient review by readers of different
interests. It is recommended that the reader reviews the subsection titles in the section
“Application of Recommendations to the United States” to find subsections of interest.
The subsections include references to the number of the specific Royal Commission recommendations so that background material can be pursued, if desirable. The context of application of the recommendations in New Zealand and the United States will first be examined,
and then the recommendations themselves will be examined for applicability in the United
States.
COMPARISON OF CONDITIONS
Commissions of Inquiry in New Zealand are authorized under the Commissions of
Inquiry Act of 1908 when situations are so unusual that no other approaches will do,
such as those in which there is considerable public anxiety about the matter; a major
lapse in Government performance appears to be involved; circumstances giving rise to
the inquiry are unique with few or no precedents; the issue cannot be dealt with through
the normal machinery of Government nor through the criminal or civil courts.
Past subjects of commission inquiry have ranged from genetic modification (2000) to
police conduct (2004) to the Pike River Coal Mine Tragedy (2010). The commissions
have broad power to obtain data and expert opinion, including subpoena power. However,
a Royal Commission is not able to determine legal rights and liabilities. Further, findings and
recommendations are not binding upon any party, including the government.

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There is no exact parallel to the wide-ranging commissions of inquiry in the United
States. Congressional investigations can only be started by Congress itself and seldom investigate physical disasters. Major building failures in the United States are normally investigated by the National Institute of Standards and Technology (NIST), and since 2002, NIST
has specific authorization for such investigations under the National Construction Safety
Team Act (NCST). Under the NCST Act, NIST and its teams have comprehensive authority
to access the site of building disaster, subpoena evidence, and access records and documents.
The Terms of Reference for the Royal Commission indicate that they are not to inquire into,
determine, or report on questions of liability. Similarly, NIST investigations do not consider
findings of fault, responsibility, or negligence (NIST 2012).
Individual states and local governments may also fund investigations into disasters, particularly since many disaster mitigation policies and authorities rest at the state- and localgovernment levels in the United States. For example, California Governor Pete Wilson issued
Executive Order W-78-94 after the Northridge earthquake in 1994. In that order, he asked the
Seismic Safety Commission to review the effects of the earthquake and to make recommendations on seismic safety and land-use planning. The Commission responded by directing the
preparation of 39 background reports on various issues (CSSC 1994), received testimony at
hearings, and commissioned 27 case studies of buildings damaged in the earthquake (R+C
1996). Based on this information, the report, Turning Loss to Gain, (CSSC 1995) was prepared, containing 168 recommendations to improve seismic safety in California. This report
may be the closest parallel to the Royal Commission’s reports, but the background investigations were far less extensive and more informal.
BUILDING INVENTORY AND DESIGN PRACTICE

The similarity of building types between Christchurch and many parts of the United
States, along with similarity in the history of the development of seismic codes and mitigation
policies suggests that many of the recommendations made by the Royal Commission will
have applicability in the United States. Many pre-1930s, low-rise, small-business commercial
buildings in Christchurch were unreinforced masonry bearing walls (URM) with timber
floors and roofs—very similar to URMs in much of the United States. Most mid-rise buildings were reinforced concrete or reinforced concrete masonry, again very similar to mid-rise
buildings in the United States, although the proportion of buildings constructed of concrete in
Christchurch was far higher than that in the United States. There are very few steel buildings
in Christchurch, whereas most mid- and high-rise commercial buildings built in the United
States in the last 40 years are steel. In that time period, concrete construction is more commonly found in mid- to high-rise residential buildings. Precast concrete also was used far
more extensively in Christchurch than in the United States, particularly for floor construction.
There are also many one- and two-story buildings with “tilt-up” precast walls in Christchurch
similar to tilt-up construction in the United States.
Seismic design codes and practices were developed and matured on similar paths in the
two countries. The development of codes was accelerated in New Zealand due to the 1931
Napier earthquake and in the United States by the 1933 Long Beach event. Codes somewhat
equivalent to today’s standards are commonly traced to the 1970s—the 1976 UBC in the
United States and NZS4203:1976 in New Zealand. Significant improvements in the design

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of reinforced concrete for seismic effects were also developed in the United States in this
period with the concept of ductile concrete introduced by Blume et al. (1961) and promulgated in the 1971 ACI 318 design provisions for concrete. In New Zealand, the highly influential Reinforced Concrete Structures by Park and Paulay (1975) was published in 1975 and
has also been widely used in the United States. The Christchurch experience in the
Canterbury swarm of earthquakes should therefore be considered very relevant to conditions
in many parts of the United States.

BUILDING REGULATORY FRAMEWORK

The Building Act 2004 is the current law on buildings and building work in New Zealand
and provides the framework for building controls. The Ministry of Business, Innovation, and
Employment (previous to 1 July 2012, the Department of Building and Housing) is the government department responsible for building policy and regulatory functions for the whole
country. Regulations under the Act include the Building Code, which in New Zealand is
formatted as performance based. In that format, the Building Code contains performance
standards for 35 different aspects of building performance. Technically, a building design
must meet these performance standards. However, there are also more detailed Compliance
Documents approved by the Ministry for each aspect of design, often referencing standards
developed by others, most commonly Standards New Zealand (www.standards.co.nz).
Designs that meet the Compliance Documents are deemed to comply with the performance
standards. Designs can also be directly shown to meet performance standards by testing, and/
or analysis. In New Zealand, local authorities, often cities, have responsibilities under the Act
to carry out building safety regulatory functions in their district.
In the United States, the building code adopted by local jurisdictions is comparable to
New Zealand’s Compliance Documents. Local jurisdictions’ regulations are primarily controlled by the code—or other rules for building construction—adopted by the various state
governments. State and local governments have ultimate responsibility for the health and
welfare of their citizens, including assurance of safe buildings. States often adopt a
model building code developed by consensus users groups, most commonly in the United
States, the International Code Council (ICC). Similar to Compliance Documents in New
Zealand, the ICC often adopts standards developed by others for various aspects of the
code provisions. Performance designs—comparable to designs directly addressing performance standards in New Zealand—are allowable in the United States under the building
code clause, Alternate Means of Compliance.
Standards used in the two countries are often parallel. For example, the New Zealand
standard, NZS 1170, Structural Design Actions (NZS 2004) is comparable to ASCE 7,
Minimum Design Loads for Buildings and Other Structures (ASCE 2010), and NZS
3101, Concrete Structures Standard, The Design of Concrete Structures (NZS 2006), is similar to ACI 318, Building Code Requirements for Structural Concrete (ACI 2005). Seismic
structural design in New Zealand is governed by two criteria: the ultimate limit state (ULS),
which is intended to protect life safety in large rare events; and a serviceability limit state
(SLS), which is intended to limit deformations and damage, in less intense, more common
events. U.S. design procedures include a parallel to the ULS, but do not currently incorporate
a SLS.

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Although the end result with respect to the construction of new buildings is most often
similar between the two countries, New Zealand’s nationally applicable Building Act and the
central authority of the Ministry of Business, Innovation, and Employment to be the government’s policy agency for building regulations enables efficient national implementation of
changes in building policies in New Zealand. Whereas each state, local government—or, in
some cases, both—must adopt such changes in the United States. Among the significant
results of this national control in New Zealand are the provisions covering “earthquakeprone” buildings (i.e., prone to significant damage), discussed below.
The genesis for the current provisions covering earthquake-prone buildings is found in
the Municipal Corporations Amendment Act of 1968, in which the concept of dangerous
buildings was expanded to include unreinforced masonry or unreinforced concrete buildings
that were found to constitute a danger to persons if their ultimate load capacity would be
exceeded by a postulated moderate earthquake ground motion—at the time, defined as
one that subjected a building to seismic forces one half as great as those specified for
new buildings. This enabled mitigation of the risks of such buildings by local authorities
similar to processes to mitigate risk from dangerous buildings already in the code. Residential
buildings were included only if they were two or more stories and contained three or
more units.
Building codes in New Zealand continued to evolve with the Building Act 1991. The
Act established the Building Industry Authority (predecessor to the Department of Buildings and Housing) as nationwide regulator for the building control system. The provisions
for earthquake prone buildings were similar to those introduced in 1968. The Building Act
1991 also changed the format of the building code to be parallel with developing international standards for performance-based design (Meacham 2010). Finally, The Building Act
2004 expanded the definition of earthquake-prone to include all building types and materials and reduced the definition of a moderate earthquake to one that generates forces 33% of
those specified for new buildings (often abbreviated by 33%NBS). Most importantly, each
territorial authority (local building regulator) was required to develop and adopt a policy
concerning earthquake-prone buildings in their jurisdiction. Typically, this included developing an understanding of the structural types, materials, and occupancies of the potentially
earthquake-prone buildings in their jurisdictions. In some cases, authorities in regions such
as Wellington with high seismicity also adopted time periods for mandatory retrofit of these
buildings.
The earthquake-prone policies of New Zealand have no parallel in the United States, not
only because there is no “national” building code in the United States, but also because no
state has adopted seismic hazard mitigation policies covering all privately owned, older,
potentially seismically hazardous buildings. Perhaps the most comparable state law to the
earthquake-prone policies is California’s Unreinforced Masonry Building Law (State of
California 1986), which required local authorities in the high seismic zones of California
to identify and adopt mitigation policies for unreinforced masonry buildings in their jurisdiction. A few local jurisdictions have, on their own, adopted policies targeting other potentially
hazardous building types such as concrete tilt-ups, non-ductile concrete, or soft/weak story
buildings, but nowhere in the United States are there policies as all-encompassing as
New Zealand’s earthquake-prone provisions.

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A more complete description of building codes in New Zealand and the United States,
along with many other countries can be found in Meacham (2010).
SEISMICITY AND SEISMIC HAZARD MAPPING

The seismicity of New Zealand and its national seismic hazard model are similar to those
of the United States. The New Zealand National Seismic Hazard Model is developed by GNS
Science (Stirling et al. 2012), which is the equivalent of the U.S. Geological Survey (USGS)
in this role. Like the USGS National Seismic Hazard Maps (Petersen et al. 2008), the
New Zealand model is built from earthquake source models and models that predict future
ground motions from each of the potential earthquakes, combined via Probabilistic Seismic
Hazard Analysis (Cornell 1968, McGuire 2004). In both countries, the earthquake source
models include both recognized “fault sources” from detailed geologic and geophysical studies and “background sources” that are based on historical earthquakes that have not been
associated with known faults. The background sources are intended to capture earthquakes
like those in the Canterbury sequence, which all occurred on faults that had not previously
been known to exist. Also, in both countries, most of the ground motion prediction models
are based on recordings of ground motions in past earthquakes that occurred locally or in
similar tectonic environments. In New Zealand, the ground motions that have a 10% probability of being exceeded in 50 years range from 0.26 g to 1.2 g (spectral acceleration at
0.5 seconds); in the conterminous United States, the corresponding ground motions range
from practically 0 g to 1.58 g.
OVERVIEW OF RESULTS OF THE CANTERBURY EARTHQUAKES
ROYAL COMMISSION OF INQUIRY
The purpose of the Commission was to examine issues related to building performance in
the Christchurch Central Business District (CBD), particularly when the performance led to
fatalities. The Commission was also required to inquire into the adequacy of the relevant
building codes and standards into the future. More specifically, commissions of inquiry
are directed by a document called the Terms of Reference, which describes the scope of
the inquiry. In the case of the Canterbury Earthquakes Royal Commission, the Terms of
Reference specified a review of the performance of four specific buildings in the CBD
already under detailed investigation by the Department of Building and Housing (DBH):
the Canterbury Television Building (CTV), the Pyne Gould Corporation Building, the Forsyth Barr Building, and the Hotel Grand Chancellor Building. In addition, the Commission
was directed to consider the performance of a “representative sample” of other buildings in
the CBD to determine why some buildings failed severely and caused injury and death. Perhaps most importantly, the Commission was to inquire into the adequacy of the current legal
and best-practice requirements for the design, construction, and maintenance of buildings in
central business districts in New Zealand to address the known risk of earthquakes (CERC
2012, Vol. 1).
It should be noted that the Terms of Reference directed the inquiry primarily at the
Christchurch CBD and at the causes of injury and death. Thus the extensive liquefaction
that caused widespread damage to homes and infrastructure in residential areas was not investigated in detail. There was also no focus on economic losses, in terms of either repair costs
or loss of use of buildings. Specifically excluded in the Terms of Reference were questions

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of liability; matters for which the Minister for Canterbury Earthquake Recovery and the
Canterbury Earthquake Recovery Authority are responsible, such as design, planning, or
options for rebuilding the Christchurch CBD; and the role and response of persons acting
under the Civil Defence Emergency Management Act 2002, generally providing emergency
and some recovery services. Therefore, although the results of the inquiry include arguably
the best publicly available data ever assembled concerning the performance of a specific
building inventory in known ground motions, the documents developed by the Commission
do not represent lessons learned in all fields of interest in earthquake reconnaissance such as
performance of bridges, ports, and infrastructure, emergency response, social sciences, and
recovery.
All investigative reports, invited subject matter papers, peer reviews, and other written
submissions are on the Commission’s website (http://canterbury.royalcommission.govt.nz/)
and will be permanently available online in archives. Most of this material was presented and
enriched in public hearings from October 2011 to September 2012, all of which is available
on the Internet by transcript and through hundreds of hours of video recordings (http://
canterbury.royalcommission.govt.nz/Hearings-Schedule).
Summary results of the Commission’s inquiry are presented in seven volumes, the organization of which was dictated by the sequence of hearings and availability of data. The
original completion date of 11 April 2012 was later extended to allow a partial delivery
by 29 June 2012, and a final completion no later than 30 November 2012. The first part
consisted of Volumes 1–3 and was submitted 29 June. Volume 4 was a second submission
on 8 October, and the final submission, Volumes 5–7, was submitted 29 November 2012.
The content of the seven volumes is summarized in Table 1.
Although formal Commission recommendations are sequentially numbered and appear
throughout the text of the volumes in the context of discussion, the recommendations are
repeated in summary form in Volumes 1, 4, and 5. The 189 formal recommendations
vary from proposed changes to specific clauses in various New Zealand design standards
to sweeping national requirements that all earthquake-prone buildings be strengthened within
7 to 15 years for URM buildings and non-URM buildings, respectively. Additional recommendations made by others in various submittals to the Commission are often highlighted in
the main body of the reports and these are not numbered, tracked, and not necessarily represented in formal Commission recommendations. These recommendations are not considered
herein.
APPLICATION OF RECOMMENDATIONS TO THE UNITED STATES
It is not feasible to review and comment on all 189 Commission recommendations in this
paper. Further, the organization of the volumes, dictated by the hearing schedule and availability of information on given subjects, does not necessarily group all Commission recommendations on a given technical or policy topic together sequentially. Therefore, the
discussion of applicability in the next section of this paper will be organized by subject
areas with potential application in the United States that are not necessarily in a sequence
consistent with the background material in the Royal Commission reports. Specific recommendations that are pertinent to applications in each topic area are referenced herein using the
format “(CR [number]).”

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Organization of Final Report of the Canterbury Earthquakes Royal Commission
Title

1

Summary and Recommendations in
Volumes 1–3
Seismicity, Soils, and the Seismic
Design of Buildings

2

The Performance of Christchurch
CBD Buildings

3

Low-Damage Building Technologies

4

Earthquake-Prone Buildings

5

Summary and Recommendations in
Volumes 5–7
Christchurch, the City, and Approach
to this Inquiry

6

Canterbury Television Building

7

Roles and Responsibilities

Contents
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Summary of Recommendations (CR1-70)
Seismicity
Introduction to the Seismic Design of Buildings
Soils and Foundations

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Pyne Gould Corporation building
Hotel Grand Chancellor
Forsyth Barr building
General observations of damage
Individual Buildings not causing death
Cost implications of changing the Seismic Zone Factor

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Seismic design philosophy
Low-damage building technologies
Professional and regulatory implementation
Cost considerations

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Summary of recommendations-(CR71-106)
Design standards and legislative history
Building types in the Christchurch CBD
Individual URM buildings that caused fatalities
URM buildings and their performance in earthquakes
Assessing and improving the seismic performance of
existing buildings
• Earthquake-prone buildings policy and legislation
• Summary of Recommendations (CR107-189)
• Christchurch’s history and impacts of the earthquakes
• The Commission’s Methodology

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CTV prior to the February earthquake
The February earthquake
Post-collapse investigations
Technical discussions on structure
Factors that contributed to collapse
Regulatory compliance issues
Summary of conclusions and recommendations

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Building management after earthquakes
Roles and responsibilities
Training and education of civil engineers
Management of earthquake risk by specific councils

SEISMOLOGY, NATIONAL SEISMIC ZONING, AND LOCAL REZONING
AFTER EARTHQUAKES

As summarized in the Royal Commission’s report (Vol. 1, Section 2.8), the ground
motions used for seismic design in New Zealand are based on output from national
probabilistic and deterministic seismic hazard models, as they are in the United States

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(ASCE 7 2010). The Royal Commission has concluded that confidence is justified in the
current processes by which earthquake hazard in New Zealand is assessed and translated
into the provisions of the relevant Standards used for the purposes of building design
(CERC 2012, Vol. 1, p. 6). However, with respect to the inputs to the seismic hazard models, the Royal Commission recommends that research continue into the location of active
faults near population centers in New Zealand (CR 1). The continuation of such research is
also needed in the United States, as evidenced by the ongoing efforts of, for example, the
Working Group on California Earthquake Probabilities (http://www.WGCEP.org) and
the Working Group on Utah Earthquake Probabilities (Wong et al. 2011). Besides identifying locations of active faults, these projects aim to quantify rates at which earthquakes
occur on faults and probability distributions for their magnitude. The same is needed in
New Zealand. Continued research on the other primary input to the seismic hazard models,
so-called ground motion prediction equations (e.g., Bozorgnia et al. 2012), is also needed in
both countries.
The Royal Commission also recommends (CR 37) that the magnitude weighting that is
applied in the New Zealand seismic hazard models be researched further in order to provide a
weighting factor for structural design that has a more rational theoretical basis (like those for
liquefaction and rockfall). The magnitude weighting factors are used to reflect the influence
of ground motion duration (which is correlated with magnitude) on the extents of damage that
occur in earthquakes. For the design response spectra in NZS 1170 (NZS 2004) at periods
less than 0.5 seconds, the factor is greater/less than unity for (moment) magnitudes greater/
less than 7.5. For the “rezoned” design spectra for Christchurch (discussed below), however,
the factor is applied at all periods, which the Royal Commission agrees is logical (CERC
2012, Vol. 1, p. 46). Magnitude weighting is not applied in the U.S. seismic hazard models
developed by the USGS, but doing so should be a topic of further research, as the Royal
Commission has recommended for New Zealand.
Four recommendations on the topic of vertical ground motions are made by the Royal
Commission: (i) to review the provisions of NZS 1170 related to vertical ground motions
(CR 2), (ii) to revise the shape of the design response spectrum for vertical ground
motions (CR 33), (iii) to consider the seismic design implications of vertical ground motions,
and iv) to identify locations where high vertical ground motions may be expected (CR 34).
Vertical ground motions recorded during the February Canterbury earthquake were
extremely high, reaching peak accelerations of 2.2 g, greater than the corresponding horizontal accelerations (CERC 2012, Vol. 1, pp. 34–35). NZS 1170 determines a vertical design
spectrum by simply reducing the corresponding horizontal spectrum by a factor of 0.7,
although its commentary notes that at locations where the hazard is dominated by a fault
closer than 10 km, it is more appropriate to not reduce the horizontal spectrum at periods
less than 0.3 seconds. Based on some of the vertical spectra observed in the Canterbury
earthquakes, the Royal Commission states that vertical design spectra determined according
to NZS 1170 are too high in the long period range and may be too low in the short period
range for structures located close to some faults (CERC 2012, Vol. 2, p. 226). In the United
States, ASCE 7-10 (ASCE 2010) determines vertical seismic load effects via a single
constant fraction of the horizontal short-period spectral response acceleration. The
NEHRP Recommended Seismic Provisions (BSSC 2009), however, determine a vertical
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acceleration based on studies by Bozorgnia and Campbell (Bozorgnia 2004) and others. The
vertical-to-horizontal ratio also considers sensitivity to earthquake distance (also a concern of
the Royal Commission), as well as to magnitude and site class. Nevertheless, this determination of vertical design spectra was not included in ASCE 7-10, at least in part because the
seismic design implications had not yet been developed. Thus, the Royal Commission recommendation to consider the seismic design implications of vertical ground motions should also
be applied by building code committees in the United States, perhaps more so for retrofit and
post-earthquake repair of potentially brittle existing buildings because columns may be more
prone to failure in response to vertical motions than in new buildings. Furthermore, the current provisions of ASCE 41-13 (ASCE 2013) related to vertical ground motions should be
reviewed, as the Royal Commission recommends for NZS 1170. More research on the effects
of vertical ground motions, particularly for brittle building components with high gravity
loading, may be needed.
On the subject of horizontal design response spectra, the Royal Commission recommends
(CR 32) that the spectral shape factors in NZS 1170 be revised for the deep alluvial soils
under Christchurch. For the horizontal spectra observed in the Canterbury earthquakes, the
current factors appear to overestimate in the short period range, and underestimate in the 2.0
to 4.0 seconds range (CERC 2012, Vol. 2, p. 226). Analogous recommendations could apply
in the United States. For example, the design spectra in ASCE 7-10 could be revised for
Seattle, WA, based on Frankel et al. (2007), who show that locations in the basin generally
exhibit higher seismic hazard than those outside the basin for periods around 1.0 second.
Such “urban” seismic hazard models have been developed, are underway, or are planned
for other cities as well (e.g., Memphis, TN; Salt Lake City, UT; and Los Angeles, CA).
As more such models are developed, revisions of design spectra in ASCE 7 should be
considered.
Also in CR 32, the Royal Commission recommends that the likely change in spectral
shape with earthquakes on more distant faults also needs to be considered. Consideration
of the differences between spectral shapes for earthquakes on nearby versus more distant
faults is also an issue in the United States. The design spectra from ASCE 7-10 are
often blends of spectral shapes for nearby earthquakes at shorter periods with those for
more distant earthquakes at longer periods. The spectral shape of the design spectrum is,
therefore, often conceptually inappropriate for modal response spectrum or response history
analyses (e.g., Reiter 1990). For this reason, so-called conditional mean spectra (Baker 2011)
are being proposed for the response history analysis provisions of the NEHRP Provisions
(BSSC 2014) and the next edition of ASCE 7.
Although they do not make a specific recommendation regarding post-earthquake
“rezoning”—that is, revising the seismic hazard factor, Z, in NZS 1170—after the
Canterbury earthquakes, the Royal Commission considers it important that the seismic
hazard factor assigned to a region should provide an accurate reflection of the area’s
earthquake hazard (CERC 2012, Vol. 2, p. 208). After the Canterbury earthquakes, the Z
factor for Christchurch was raised from 0.22 to 0.3 to reflect the potential for aftershocks
and triggered earthquakes (of comparable size to the Canterbury earthquakes) in the region
for a number of decades (Gerstenberger et al. 2011). Whether analogous increases in design
response spectra should be made after large earthquakes in the United States should be

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discussed by the USGS and U.S. building code committees, not to mention representatives of
local jurisdictions. Time-dependent increases or decreases in design spectra based on the
amount of time since the most recent earthquake on highly active faults has been broadly
discussed (e.g., Wesson 2006), but increases for aftershocks and triggered earthquakes have
not been. The United States should consider establishing a process to help local and state
jurisdictions make informed decisions about seismic design criteria for the recovery phase
that include consideration of aftershock potential.
Motivated by the increase in the NZS 1170 seismic hazard factor for Christchurch after
the Canterbury earthquakes, the Royal Commission considered the cost implications of
increasing the hazard factor on the design of new buildings (CERC 2012, Vol. 2, Section 7).
Such cost implications also need to be quantified in the United States, particularly in the New
Madrid Seismic Zone region where concern about the cost implications has prevented adoption of the design response spectra in ASCE 7-10 by some local governments. A NEHRP
Consultants Joint Venture project entitled “Cost-Benefit Analysis of Codes and Standards for
Earthquake-Resistant Construction in Selected U.S. Regions (Task Order 16)” is underway.
Similar research is needed on the cost implications and benefits (e.g., future repair costs
prevented) for retrofit and post-earthquake repair of existing buildings. In Christchurch,
the increase in the seismic hazard factor has resulted in a corresponding increase in the number of buildings identified as earthquake-prone, per the “33%NBS” definition previously
described. The extent of retrofit, when required, is also significantly affected by the seismic
loading used.

GEOTECHNICAL CONSIDERATIONS

The geotechnical conditions in the Christchurch CBD were variable and often poor.
There was considerable damage due solely to liquefaction and differential settlement.
The Commission recommended that thorough and detailed geotechnical investigations
be carried out at each building site and guidelines be developed to assure more uniform
standards for such investigations (CR 3–4). Further it was recommended that the local jurisdiction keep copies of all site assessments and maintain a public database describing subsurface conditions (CR 5–6). In the United States, geotechnical reports are required by code
to be submitted to the governing jurisdiction for most building structures. However, the
reports are seldom reviewed, nor are the data extracted into a separate database. In jurisdictions with poor or seismically sensitive soils, such a public database would be very valuable. The Commission also recommends further research into the performance of
foundations in the Christchurch CBD in the Canterbury swarm of events to better inform
future practice (CR 9). Ground motions from earthquakes create the best test of design
practices, so this recommendation will definitely be applicable for future U.S. earthquakes.
Although the Geotechnical Extreme Events Reconnaissance organization (GEER; http://
www.geerassociation.org) often performs such studies in a practical case study format,
resources are always limited, and these efforts could be expanded. Similarly, more systematic, multidisciplinary investigations into all aspects of building performance and societal
response that historically have been coordinated by the Earthquake Engineering Research
Institute in the United States are clearly essential to effectively identify lessons from these
events.

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FOUNDATIONS

In light of extensive damage caused by differential settlement, the Commission recommends more careful consideration of foundation design parameters in the serviceability limit
state (SLS), particularly in poor soils, limiting settlements to assure building performance
consistent with the intent of the SLS (CR 10–11). As previously mentioned, the United States
does not currently include a SLS, although overall code performance is being reviewed in the
2015 NEHRP Provisions (BSSC 2015) update cycle, and serviceability requirements are
being considered for some buildings.
For designs at the ULS, the Commission recommends careful consideration of deformations, including overstrength load cases. In addition, it is recommended that factors currently
used for the load and resistance factor design (LRFD) of foundations for seismic actions be
reassessed (CR 14–20). U.S. code committees have debated incorporation of both overstrength factors and LRFD methods for foundation design for some time. Although incorporation of overstrength loads is logical, there is little field data indicating that this is a life
safety issue for U.S. buildings and the potential costs of such requirements have been a concern. New Zealand experience should be studied when considering incorporation of both
overstrength and LRFD design into U.S. Codes.
Lastly, material that the Commission collected indicated a lack of consensus
guidelines for soil improvement and installation of deep foundations in New Zealand.
Recommendations were made that such guidelines be developed (CR 21–31). There
are few non-proprietary guidelines covering these subjects available in the United States,
other than textbooks. The California Geological Survey has issued SP 117a, Guidelines
for Evaluating and Mitigating Seismic Hazards (CGS 2008), as part of the Seismic
Hazards Mapping Act Program. Other non-proprietary guidance to design professionals
confronted with building code requirements for mitigation of site seismic hazards is
not known. However, rules to determine effects on new structures during design for
site settlements from liquefaction or soil failure have been developed in Vancouver,
B.C. (Task Force 2007), ASCE 41 (ASCE 2013), and are proposed for the 2015
NEHRP Provisions (BSSC 2015).
For a more detailed analysis of the performance of sites with improved ground in these
earthquakes, see Wotherspoon et al. (2014) in this issue.
An example of a U.S. guideline for deep foundations is a Federal Highway Administration document on continuous flight auger piles (Geosyntec Consultants 2007). In general, in
the United States, there is far less non-proprietary consensus–based guidance available for
geotechnical issues than for other aspects of building design (structural, mechanical, fire
safety, etc.). The need for such standardization is unclear and, unfortunately, probably cannot
be determined until strong ground motion occurs over a large urban area and performance
resulting from the current state of practice can be gauged.
CHANGES TO STRUCTURAL DESIGN AND EVALUATION STANDARDS
AND GUIDELINES

There are at least 39 recommendations for improvements to building design and evaluation provisions and/or design practice common in New Zealand. These range from a specific

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recommended change in the concrete standard to prevent buckling in axially loaded walls
(CR 44, primarily due to the primary failure mode of the Hotel Grand Chancellor) to a broad
five-point recommendation for improvement in the processes of assessment of seismic
performance in buildings (CR 109, primarily from the various investigations into the collapse
of the CTV building). Due to the parallels in codes, standards, and practices between
New Zealand and the United States previously discussed, all of these are relevant in the
United States and should be reviewed in detail by appropriate code development committees.
However, the applicability, as measured by the need for improvement in U.S. codes or practice specific to each recommendation, varies considerably. For example, the issues of torsional irregularity (CR 35), and design of diaphragms (CR 36), are already clearly considered
in U.S. codes and practice. However, the effectiveness of these provisions need further study.
In fact, diaphragms are under study as part of the development of the 2015 NEHRP Provisions (BSSC 2015). On the other hand, the following topic areas are highlighted (in no particular order) as having a high potential to be improved in U.S. practice, either by research in
the topic area, or changes to codes or standards:
•

•

•

•

•

•

The need to identify the sites and types of structures where vertical ground motions
could have a significant effect on overall structural performance and to develop
simplified methods to account for such motions (CR 34).
Several recommendations relate to the elongation implied by material strains and/or
assurance that the yielding of reinforcement can extend beyond the immediate vicinity of a single primary crack (the source of possible bar fracture) (CR 41, 42, 46,
47, 48, 49, 57, 59, 109). This recommendation is in response to observations in
several buildings with concrete shear walls that had hairline cracks where subsequent removal of concrete uncovered fractured reinforcing steel.
Elements of buildings susceptible to damage or failure from drift, most importantly
but not limited to gravity load carrying systems and stairs, should be evaluated for
stability at realistic drift levels, including the potential of drifts exceeding those
specified in the code (CR 58, 60, 62, 63, 109,110).
Acceptability criteria should be developed for the various configurations of lightly
reinforced concrete fills over precast concrete elements used as diaphragms in older
concrete buildings (CR 61).
Although the Commission’s Terms of Reference emphasized concerns from injury
and loss of life, nonstructural damage in the CBD was extensive in the February
event and largely overlooked, due to the many buildings with significant structural
damage. Despite strong code provisions in the United States to protect nonstructural
elements, implementation is not thorough or consistent (Masek 2009). Methods to
improve implementation should be pursued by design professionals, government,
and the construction industry (CR 64, 65, 70).
Twenty-foot cantilevers on one face of 25 floors of the Hotel Grand Chancellor
created a significant gravity-driven lateral force on the building. Asymmetrical sloping columns could create the same effect. It is not apparent that this interaction of
gravity and seismic lateral load was a significant contributor to the damage in HGC
but such systems will exacerbate transient drift and increase the potential for residual drift due to ratcheting. Code provisions for such situations have been considered in Canada (Dupius 2013). These conditions may become more common as

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architects seek new forms for their buildings, and code provisions should be considered for the United States. (CR 56).
Commission Recommendation 109, resulting primarily from the investigation into the
collapse of the CTV Building, is multifaceted and particularly important. It includes recommendations that building evaluators more clearly recognize (i) the critical capacity of the
structure to resist gravity loads while being laterally displaced, (ii) the importance of a complete load path without weak or brittle components, and (iii) the inability of sophisticated
analysis to predict exact damage patterns and failure modes. These recommendations are
applicable worldwide.
INNOVATIVE (LOW DAMAGE) TECHNOLOGY

The Royal Commission’s Terms of Reference include the need to consider the adequacy
of the current legal and best practice requirements for the design, construction and maintenance of buildings in central building districts (CBDs) throughout New Zealand. The severe
damage in the CBD of Christchurch in the February earthquake, even though the motions
were more intense than expected based on code mapping, led many in New Zealand to question if the performance was as expected and/or adequate. The Commission concluded that
performance could be improved by increasing the level of design ground motions (see previous section on seismology), by making incremental improvements in Compliance Documents and practice (see previous section on changes to design standards), or by more often
employing systems specifically developed to minimize damage. Such systems include base
isolation, use of supplemental dampers and other energy absorbing structural systems, use of
replaceable structural fuses, and self centering structural systems that minimize residual drift.
Recommendations to continue research into low-damage systems, to ease approval processes to enable more wide-spread use, and to foster more communication about these systems among building owners, designers, and building authorities are all applicable in the
United States (CR 66, 67, 69).
INVENTORIES OF EARTHQUAKE-PRONE BUILDINGS

The Royal Commission recommends that all jurisdictions in New Zealand establish and
maintain inventories of buildings prone to collapse in earthquakes (CR 101). In California,
286 jurisdictions closest to active earthquake faults inventoried 26,000 URM buildings,
approximately 1 out of 500 buildings in the State. Several hundred California local governments still keep lists of building owners, addresses, and their retrofit status, but for the most
part, these inventories are not required by law to be maintained, nor have they generally been
maintained or updated since 2006 (CSSC 2006). In regions of California with moderate or
lower seismicity similar to Christchurch, URM inventories are not required, nor do they exist,
except for hospitals and public schools. California also maintains an inventory of 2,673 hospital buildings and has recently begun to update its inventory of public schools
(CalEMA 2010).
In other states, such as Utah, Oregon, and Washington, partial URM inventories or sampling, particularly of school buildings, were developed in response to initiatives to conduct
seismic evaluations and retrofits (Utah 2011, Oregon, 2012, Washington, 2010). For example, Oregon inventoried and evaluated 3,352 educational and emergency services buildings

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(DOGAMI 2007). Utah’s legislature has urged the state’s Seismic Safety Commission to
begin to inventory the state’s URM buildings, estimated to exceed 185,000 in number
(FEMA 2009). Since collecting an inventory of vulnerable buildings is often recommended
as a first and required step for mitigation, this recommendation is applicable to most of the
highly seismic regions in the United States. Considering the potential life safety risks from
typical URM damage at moderate ground motion levels, as demonstrated in the September
Darfield earthquake and elsewhere, similar, but perhaps more focused, inventories should be
collected in moderate seismic zones of the United States.
UNREINFORCED MASONRY BUILDINGS

The Royal Commission recommends that all URM buildings be evaluated and retrofitted
throughout New Zealand within seven years (CR 82 and 83). By comparison, in California’s
regions of high seismicity, 55% of the inventoried URM buildings have been retrofitted and
15% demolished through programs enacted by local governments that, for the most part, took
place from the 1970s to the late 1990s (CSSC 1995, 2006). Such programs included locally
adopted regulations that required materials testing, inspection, and retrofit plan reviews by
regulators. However, 30% of California’s URM buildings in high seismic regions and all of
those in low and moderate seismic regions in the state are in jurisdictions that have not consistently enforced seismic evaluation and retrofit programs. Very few, if any, jurisdictions in
other states have undertaken any kind of mandatory URM retrofit program. This recommendation is therefore applicable in many cities in the United States. Time periods as short as
seven years have sometimes proven problematic for mandatory retrofit in the United States,
and the length of such programs is probably best left up to each local jurisdiction.
For a more detailed description of the performance of URM buildings in the Canterbury
swarm of earthquakes, see Moon et al. (2014) in this issue.
EARTHQUAKE PRONE BUILDING POLICIES NOT LIMITED TO URM

In the February 2011 earthquake, collapses of the previously partially retrofitted, nonductile concrete Pyne Gould and CTV buildings killed 18 and 115 people, respectively. Since
2004, New Zealand’s Building Act has required all local governments to establish policies to
address the risks of earthquake-prone buildings regardless of construction type. The Royal
Commission recommends that all earthquake-prone buildings be inventoried, evaluated and
retrofitted within 15 years (CR 82, 83, and 101). New Zealand’s existing law and these latest
recommendations far exceed any policies enacted anywhere in the United States.
In addition, the Royal Commission recommends that New Zealand enact regulations for
seismic evaluations and retrofits (CR 73). To date, engineers have used the New Zealand
Society of Earthquake Engineering Recommendations (NZSEE 2006), which do not have
regulatory standing and are thus a concern to the Commission for consistency of application.
The United States has had consensus standards available for seismic evaluation, ASCE 31
(ASCE 2003), and retrofit, ASCE 41 (ASCE 2007) for some time. However, until recently,
adoption of these standards has been at the local level.
The International Building Code, the most widely adopted model code in the United
States, has referenced ASCE 31 and ASCE 41 since 2012. In addition, 24 states have adopted
various editions of the International Existing Building Code (IEBC), which contains seismic

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evaluation and retrofit provisions including minimum material testing, inspection and plan
review requirements (ICC 2012a, ICC 2012b). The 2015 IEBC will likely reference a
recently merged standard titled Seismic Evaluation and Retrofit of Existing Buildings
(ASCE 2013). These codes primarily target seismically vulnerable buildings through
major alterations that can trigger seismic evaluations and retrofits. As a result a considerable
but unknown number of voluntary retrofits or those triggered by alterations have been completed throughout the western United States. Since 1992, California has adopted retrofit regulations applicable statewide specifically for bearing-wall URM buildings (ICC 2013). Years
when other state and local governments began to enforce standard and consistent regulations vary.
So while seismic evaluation and retrofit standards that may be triggered upon major
alterations or repairs have been available in the United States, only six cities in California
have enacted programs to require or encourage evaluations and retrofits for older buildings
other than URMs (CalEMA 2010). In addition, hospitals and public schools in California
have been required to undergo evaluations and, if warranted, to also require retrofits or replacements (CSSC 2004, OSHPD 2012). Oregon and, more recently, Utah have been undertaking inventories and evaluations of critical government buildings including schools in high
seismic regions (Oregon 2012, Utah 2011). Throughout the western United States, a small
percentage of non-URM older buildings have been evaluated and retrofitted, predominantly
by institutional owners that have long-term interests in their buildings. Although a national
U.S. law to mitigate seismically hazardous buildings of all types is not possible, and state
laws that affect the general inventory are unlikely, the Commission recommendation to
extend mitigation of hazardous buildings beyond URMs is applicable to many jurisdictions
in the United States, particularly for targeted building types like non-ductile concrete.
The Royal Commission recommends that communication to the public about earthquakeprone buildings be improved (CR 102 to 105) by establishing a uniform building seismic
performance grading system (CR 72) and by clarifying expected performance of new buildings, older buildings and retrofit older buildings (CR 76). In the United States, a building
grading system has been drafted but not yet implemented (SEAONC 2012, USRC 2013).
Remaining issues include means to engage real estate market influences to accomplish the
purpose of placing a monetary value on seismic performance and assuring quality control for
rating assignments. However, widespread lack of public awareness in the United States about
the risks posed by the older building stock in earthquakes is still apparent and has not been
adequately addressed (FEMA 1998).
The Royal Commission recommends that laws be enacted to require a strict duty for
building owners, design professionals, and regulators to disclose risks posed by seismically
damaged buildings to inform building occupants and the general public (CR 93 to 95). In
addition, engineers should be required to report structures that present health and safety risks
to authorities even if not damaged (CR 183). The target of CR 183 appears to be earthquakeprone buildings with critical structural weaknesses, presumably seismic. It is expected that, in
the United States, these two situations would be quite different. In California, due to an
Attorney General’s Opinion written in 1985 (AG 1985), an engineer retained to investigate
a building’s integrity, who determines that there is an imminent risk of serious injury and who
is advised by the owner that no disclosure or remedial action is intended, has a duty to warn

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occupants or building officials. Although never tested in court, the use of the word
“imminent” is widely interpreted as relatively immediate (such as from gravity loading present or expected, or from an expected aftershock) and not from damage from an earthquake
with a completely unknown occurrence time. It is expected that in the post-earthquake situation, a voluntary review by an engineer that revealed damage would result in “tagging” the
building and notification of the local jurisdiction. Although not clearly stipulated, professional societies have generally suggested that the duty to warn occupants and building officials does not extend to voluntary seismic evaluations not related to post-earthquake damage,
on the basis that such a duty would stifle such evaluations and do more harm than good.
However, appropriate professional behavior in the two different situations is not widely
understood, nor published, nor is it required to be taught to candidates who seek engineering
and architecture licenses. At the least, these recommendations related to duty-to-warn would
indicate a need to clarify professional responsibility in the United States.
The Royal Commission also recommends that demolitions, barricades, emergency stabilizations and other emergency protective works for reducing the risks of severely damaged,
earthquake-prone buildings should no longer require building permits (called “consents” in
New Zealand; CR 100). In addition, efforts by preservationists to delay demolitions, concerns
about the environmental impacts of asbestos releases during demolitions, and other regulatory impediments in the United States have also caused major delays and invariably exposed
the public to significant risks (Arnold 1998, Mesothelioma Center 2013). U.S. codes do grant
regulators considerable discretion for reducing or eliminating imminent risks; however, once
urgent situations have been addressed, historic preservation, intransigence by owners, and the
lack of funds for repairs have significantly delayed recovery efforts. In addition, the lack of
comprehensive and uniformly applicable post-earthquake repair regulations has slowed
recovery in the United States by rendering options for repair versus strengthening versus
demolition ambiguous and uncertain. The International Existing Building Code contains provisions that delineate when strengthening is required in addition to repair for buildings with
various level of damage (ICC 2012a). Uncertainty in identification of circumstances that
would require strengthening of damaged buildings led San Francisco recently to adopt
more comprehensive post-earthquake repair provisions in 2012 (SF 2012).

POST-EARTHQUAKE SAFETY TAGGING AND CORDONING

Several buildings that had been green-tagged in previous events of the Canterbury swarm
collapsed in the February 2011 earthquake and focused attention on New Zealand’s
post-earthquake building safety evaluation program. The Royal Commission included
many recommendations regarding post-earthquake evaluations of buildings, including
that New Zealand enact legislation for its entire program (CR 113 to 115). In the United
States, no such state or federal legislation exists. However, the organization of California
Building Officials (CALBO) recommends that local governments adopt a model ordinance
that “authorizes the Building Official and his or her authorized representatives to post the
appropriate placard at each entry point to a building or structure upon completion of a safety
assessment” and makes removal or alteration of red, yellow, or green tags on buildings an
unlawful offense (CALBO 2004). No data are available on the extent to which these recommendations are adopted in California or elsewhere.

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The Royal Commission recommends that New Zealand work with the international
building safety evaluation community to refine consensus on international safety assessment
practices (CR 143). They also recommend that:
•
•
•

•

•

Guidelines be developed for those entering damaged buildings (CR 124 to 126).
The threat of aftershocks should be considered in safety assessments (CR 116, 117).
Indicator buildings be used to speed decisions about the need for re-evaluations by
formalizing the sampling of previously evaluated buildings after subsequent earthquakes (CR 138).
The color of the green placards should be changed to white because the green color
reinforces a commonly held misconception that buildings are not collapse risks and
need not be evaluated further (CR 143).
Plan-based assessments and other, more-detailed engineering evaluations appear to
be warranted for earthquake-prone buildings even when tagged green (CR 151).

Like New Zealand, the United States uses a post-earthquake safety evaluation system
based primarily on guidelines developed by the Applied Technology Council and published
in the ATC 20 series (ATC 2005). In 2011, discussions started between representatives from
New Zealand and ATC that will result in a report on the Christchurch sequence by ATC.
ATC is also making plans to develop an update of ATC 20 considering the Christchurch
experience. See Galloway et al. (2014) in this issue for a full discussion of these issues.
However, regarding application of the specific Commission recommendations above, it
should be noted:
•
•

•

ATC already has a document regarding entering damaged buildings (ATC 1996).
This document should be reviewed and updated for use in the United States.
Aftershocks are already major considerations in the ATC 20 system. For both
practical and technical reasons, the current recommendations assume aftershock
shaking equal to the largest, prior damaging event. In the United States, consideration of more intense shaking, as occurred in Christchurch, will be difficult for the
rapid or detailed tagging evaluations, but could be considered for later engineering
evaluations.
Requirement for engineering evaluation of buildings already tagged green is unlikely to become policy in the United States due to practicality and cost. However,
local jurisdictions with active seismic mitigation programs and inventories of potentially hazardous buildings may chose to use the occurrence of an earthquake to
achieve accelerated mitigation by requiring evaluation and even retrofit of selected
buildings. However, some policy makers have expressed concern that such programs may slow or inhibit recovery (ATC 2010).

Decisions about barricading and stabilizing damaged buildings drew the attention of the
Royal Commission. In one case, unstabilized, damaged storefront walls on a row of URM
buildings fell beyond barricades, killing 12 in the public right of way. The Royal Commission recommends that more comprehensive policies for erecting and maintaining barricades
and cordons be established (CR 156–159). After past earthquakes in the United States, barricading and stabilization to ensure the public’s safety has often been inadequate and poorly
maintained. In January 2012, CalEMA issued revised training curricula for its Safety Assessment Program Coordinators that more rigorously address barricading practices for damaged

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buildings as a result of observations in Christchurch (CalEMA 2012). In early 2013, the
California Building Officials organization indicated it is planning to release interim guidelines for barricading and stabilization practices after learning from Christchurch’s experience
(CALBO 2013).
QUALIFICATIONS OF BUILDING STRUCTURAL DESIGNERS

Evidence presented to the Royal Commission frequently described inadequacies in building designs and ineffective reviews of plans by regulators. The Royal Commission recommends that complex structures be designed and reviewed by Recognized Structural
Engineers, a new class of engineers that would meet requirements beyond the current license
requirements for Certified Professional Engineers (CPEngs). Recognized Structural Engineers
would receive a license only after completing more extensive training than CPEngs, gaining
sufficient experience, and taking a test (CR 168). Definitions for what characteristics make
structures complex will need to be defined in regulations. The Royal Commission is also calling
for continuing education of engineers to be required to maintain licenses to practice (CR 178).
In the United States, ten states have licenses for Structural Engineers that require qualifications, training, experience, and testing beyond that required for Civil Engineers
(Schmidt 2005). However, many states only require Structural Engineers for a few types
of structures such as acute care hospitals, other essential services buildings or public schools.
Some of these building types are not necessarily complex but are expected to have superior
performance. Conversely, many complex structures with nonessential occupancies are not
required to be designed or reviewed by Structural Engineers. Most building departments
(consent authorities) do not currently have Structural Engineers on their staff, nor do
they contract out to Structural Engineers for their plan review services.
In addition, regulators and engineering organizations can readily draw insights from
reviewing the Royal Commission’s detailed case studies that include plans, calculations,
and testimony from both designers and regulators. Poor quality in design and construction
and ineffective regulations were significant factors in both buildings and land improvements
with excessive damage in Christchurch, echoing many past policy recommendations that
have called for eliminating shoddy construction such as after the 1933 Long Beach, 1964
Alaska, 1971 San Fernando, and 1994 Northridge earthquakes (Turner 2004, CSSC 1995).
LOCAL MANAGEMENT OF THE RISK OF LIQUEFACTION

Although the Royal Commission was not directed to investigate economic losses, particularly outside the Christchurch CBD, the damage to the suburbs of Christchurch, particularly to the infrastructure, could not be overlooked. Entire neighborhoods were zoned as not
repairable or maintainable after the February event, primarily due to the expected expense of
current and probable future repairs to infrastructure. In CR 186–189, the Commission recommends that local authorities be aware of the seismicity of their region and include that knowledge in regional and local planning. The local authorities should also provide policy guidance
as to where and how liquefaction risk ought to be avoided or mitigated. Finally, developers of
large tracks of land should undertake geotechnical investigations to identify the risks of liquefaction, lateral spreading, and other soil conditions that could contribute to structural or infrastructure failure in expected ground motions.

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In the United States, geotechnical investigations, including considerations of potential
geologic and seismic hazards, including slope instability, liquefaction, differential settlement,
and surface displacement due to faulting, have been required by the IBC since 2006 for structures assigned to Seismic Design Category C, D, E, and F (generally in areas of moderate and
high seismicity). However, the level of enforcement of this requirement, review of the
reports, and mitigation required is less clear. Further, the International Residential Code,
directed at one and two story residential structures, does not explicitly list seismic hazards
as a concern for geotechnical reports, and does not require geotechnical reports for all projects (ICC 2012a). Therefore, the Royal Commission’s concerns about liquefaction, particularly the potential effect on the infrastructure of large residential developments is
potentially applicable in parts of the United States and approval procedures for construction
in questionable areas should be reviewed.
For further discussion of liquefaction-induced land damage not directly related to the
Royal Commission reports, see the paper by van Ballegooy et al. (2014) in this issue.
CONCLUSIONS
Recommendations of the Canterbury Earthquakes Royal Commission of Inquiry have
been reviewed for applicability in the United States in the topic areas of seismology and
hazard mapping, geotechnical, foundations, structural design and evaluation standards, innovative technology, vulnerable older buildings, post-earthquake safety evaluations, qualification of building structural designers, and management of the risk of liquefaction. Based on
current legislation, policies, and procedures in the United States, many of the recommendations are applicable and the report represents an extraordinary “learning from earthquakes”
document from the Canterbury swarm in the subject areas covered (primarily related to performance of buildings). Various recommendations can be directed toward U.S. federal, state,
and local governments in both the areas of code enforcement and emergency management,
consensus-building code writing groups, and professional practitioners in several disciplines.
Implementation of any of the recommendations will therefore have to be piecemeal, by the
agencies or organizations affected. It is recommended that individuals interested in implementing recommendations review the full Commission report text regarding the individual
recommendations to better understand the circumstances that led to them.
ACKNOWLEDGEMENTS
The authors would like to recognize and thank the Canterbury Earthquakes Royal Commissioners Honorable Justice Mark Cooper (Chairperson), Sir Ronald Carter, and Adjunct
Associate Professor Richard Fenwick, as well as their staff for their extraordinary efforts.
They will clearly benefit the advancement of earthquake risk management in the United
States.

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(Received 6 March 2013; accepted 30 November 2013)