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▲▲Figure 6. Computed median inter-story drift demands (%) on two-story timber structures:maximum of all possible recording directionsis considered (coefficient of variation of the results: 31%).▲▲Figure 7. Computed median inter-story drift demands (%) on six-story RC frame structures:maximum of all possible recording directionsis considered (coefficient of variation of the results: 19%).▲ ▲ Figure 8. Computed median inter-story drift demands (%) on 17-story RC frame structures:maximum of all possible recording directionsis considered (coefficient of variation of the results: 19%).890 Seismological Research Letters Volume 82, Number 6 November/December 2011
▲ ▲ Figure 9. Representative buildings for the considered categories: timber residential house (left), mid-rise RC structure (middle), andtall RC structure (right).retical finding. Analyses on one-story timber structures withsimilar assumptions showed that the expected drift demandswere quite limited, thus explaining the low damage ratio ofone-story houses.The computed spatial distribution of the median inter-storydrift demands for six-story RC frames is portrayed in Figure 7,which shows that the highest demands on such structures, inthe order of 3.0–3.5% inter-story drifts, are concentrated in theCBD—which explains the damage on mid-rise RC structuresduring the February 22 earthquake. Interestingly, the computeddamage potential for such structures specifically reaches its climaxin the CBD. Readers are reminded that both the CTVand PGC buildings, which fatally collapsed from the Februaryshaking, were mid-rise RC structures constructed on soft soil.Tall RC frame structures in the CBD, though limited innumber, also experienced some extent of damage with the mostcharacteristic case being that of the Grand Chancellor Hotel, a26-story wall-frame structure that was rendered unusable dueto large residual displacement. The building we chose to lookat, the Clarendon Tower, underwent significant but repairabledamage. Nevertheless, the building will be demolished as notmeeting insurance standards. The findings illustrated in Figure8 exhibit 0.6% to 0.8% median inter-story drift demands forsimilar 17-story structures, a drift level that certainly translatesinto damage but remains below the unrepairable drift limits inline with field observations (Tasiopoulou et al. 2011).The inter-story drift demands reach their peak in the CBDas shown in Figure 8, a fact that could arguably be attributedto the characteristic bulges appearing in the response spectra(Figure 1) in the range of long periods. The elastic fundamentalperiod of such structures is estimated around 2 sec, whilethe yield period (beyond which significant damage arises), isof the order of 5 sec (Crowley et al. 2004). The effective secantperiod, for example, is expected to elongate up to about 7 secin the case of an overall ductility equal to 2, as computed withthe approximate expression for effective period of Priestley andKowalsky (2000).CONCLUSIONSDamaging earthquakes feature large variations in spatial distributionof the strong ground motion parameters, a fact that ismostly attributed to the complexity of source mechanism, radiationpattern, and site conditions. The M w = 6.3 Christchurchearthquake was a surprising and unusual event which occurredin an unknown fault that had already been awakened by theSeptember 2010 stronger earthquake, and it had a strong thrustcomponent and a steeply dipping plane.This paper has attempted to identify quantifiable parametersthat could provide better insight to seismologists and engineerswho try to systematically investigate the reasons behindthe structural and soil failures that occurred in the Februaryshaking. The study focuses on connecting the basic features ofthe recorded strong motions to the nonlinear behavior of thesoil layers. Liquefaction, a phenomenon that played a majorand devastating role, has been examined through a “generic”downtown soil profile and dynamic effective stress analysis.The LPCC record was applied as the base excitation, as it wasthe only available rock outcrop motion. Despite several uncertainties,the output spectra obtained from the liquefactionanalyses and the one recorded in the free field in the BotanicGardens have shown quite a satisfactory match provided thatthe compared spectra are aligned with the strong direction ofthe recorded motion. The dominant direction of the CBGSrecord is consistently almost parallel to the fault plane whilethe Lyttelton record exhibits more inconsistencies, somethingthat may be related to the effects of the hanging wall and thesteep thrust-fault plane. The governing direction of each recordhas been found by simply turning the record in every possibledirection with one-degree intervals and re-recording the strongmotion parameters sought—a venerable procedure to uncoverthe dominant direction of the shaking of a given site.The paper concludes with an effort to better explain thereasons why some particular structural types showed bad performancein the CBD area. Short, medium, and long periodSeismological Research Letters Volume 82, Number 6 November/December 2011 891
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Volume 82, Number 6 November/Decemb
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News and Notes (continued)Nominatio
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Preface to the Focused Issue on the
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TABLE 1Peak ground acceleration (PG
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▲▲Figure 2. A) Sketch of the
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▲▲Figure 4. A) Adopted moment r
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▲▲Figure 7. As in Figure 6 but
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▲ ▲ Figure 8. Misfit parameters
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▲ ▲ Figure 10. Spatial variabil
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▲ ▲ Figure 12. Standard spectra
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Quigley, M., R. Van Dissen, P. Vill
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slip on a 59-degree striking fault
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▲▲Figure 4. Convergence of inve
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observations and other source studi
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-42. 5-43. 0-43. 5-44. 0-44. 5-43.2
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“Product CSK © ASI, (ItalianSpac
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TABLE 2Solutions for fault location
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-43.45(A)degrees N-43.50-43.552.52.
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is still a good fit to the horizont
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Coulomb Stress Change Sensitivity d
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mation takes on a larger strike-sli
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P 9.4267BLDU45P 20.1213CASY39P 2.62
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ERMJNUMAJOINUJHJ2CBIJMIDWJOWYHNBTPU
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(A)6.146.13(B)6.246.36Misfit6.156.1
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(A)(B)(C)(D)▲▲Figure 10. The co
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(A)(B)(C)(D)▲▲Figure 12. The co
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Luo, Y., Y. Tan, S. Wei, D. Helmber
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−44˚00' −43˚00'4-Sep-2010Mw 7
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TABLE 1Pairs of SAR imagery used in
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Depth (km)Coulomb Stress Change(bar
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Crippen, R. E. (1992). Measurement
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AlpineFaultHope Fault38 mm/yr0+ +-1
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σ 1dσ 3Nuσ 3CM w 7.1dw 6.2u70°M
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Right-lateral Faults(A) Range Front
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DISCUSSIONThe 2010-2011 Canterbury
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Large Apparent Stresses from the Ca
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▲ ▲ Figure 2. Observed vs. pred
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10Obs SA(1s)AS1AS+SDAB 2006AB+SDSA(
Page 85 and 86: Fine-scale Relocation of Aftershock
Page 87 and 88: −43.25°OXZ0 10 20km−43.5°−4
Page 89 and 90: A’0 km 4 8−43.5°B’B−43.6°
Page 91 and 92: REFERENCESAvery, H. R., J. B. Berri
Page 93 and 94: ▲ ▲ Figure 2. A) shows three-co
Page 95 and 96: ▲ ▲ Figure 4. Vertical accelera
Page 97 and 98: 0.8PRPC Z0.40Normalized (Max PGA +
Page 99 and 100: Near-source Strong Ground MotionsOb
Page 101 and 102: (A)Magnitude, M w876542009 NZdataba
Page 103 and 104: Scale0.5 g5 seconds▲▲Figure 4.
Page 105 and 106: (A)(B)Spectral Acc, Sa (g)North/Wes
Page 107 and 108: Vertical-to-horizontal PGA ratio543
Page 109 and 110: (A)(B)Station:CCCCSolid:AvgHorizDas
Page 111 and 112: REFERENCESAagaard, B. T., J. F. Hal
Page 113 and 114: ▲ ▲ Figure 1. Shear-wave veloci
Page 115 and 116: Spectral Acceleration (0.3 s), (g)I
Page 117 and 118: Spectral Acceleration (3 s), (g)In[
Page 119 and 120: TABLE 1Mean (μ LLH ) and standard
Page 121 and 122: Strong Ground Motions and Damage Co
Page 123 and 124: ings and the Modified Takeda-Slip M
Page 125 and 126: high, but there were no buildings d
Page 127 and 128: REFERENCES▲▲Figure 8. Heavily d
Page 129 and 130: (A)(B)(C)(D)(E)▲▲Figure 1. A) M
Page 131 and 132: (A) (B) (C)▲ ▲ Figure 3. A) Typ
Page 133 and 134: (A) (B) (C)▲ ▲ Figure 4. A) Typ
Page 135: Case StudyKey ParametersTABLE 1Key
Page 139 and 140: Soil Liquefaction Effects in the Ce
Page 141 and 142: ▲ ▲ Figure 2. Representative su
Page 143 and 144: Location of structures illustrated
Page 145 and 146: Shading indicates areaover which pr
Page 147 and 148: 1.8 deg15 cmGround cracking due to
Page 149 and 150: 30 cm17 cm30 cmFoundation beam▲
Page 151 and 152: Comparison of Liquefaction Features
Page 153 and 154: (A)(B)▲▲Figure 2. A) Simplified
Page 155 and 156: (A)Acceleration (Gal)6004002000-200
Page 157 and 158: (A)(B)▲▲Figure 7. Distribution
Page 159 and 160: (A)(B)▲▲Figure 10. Damage to a
Page 161 and 162: (A)(B)▲ ▲ Figure 14. A) Subside
Page 163 and 164: ▲▲Figure 17. A trench in a resi
Page 165 and 166: Ambient Noise Measurements followin
Page 167 and 168: ▲▲Figure 1. Location of the noi
Page 169 and 170: ▲▲Figure 5. Site N20 showing HV
Page 171 and 172: ▲▲Figure 8. Comparison between
Page 173 and 174: Use of DCP and SASW Tests to Evalua
Page 175 and 176: ▲ ▲ Figure 2. Aerial image of C
Page 177 and 178: (A)(B)▲▲Figure 4. DCP test bein
Page 179 and 180: ▲▲Figure 7. SASW setup at a sit
Page 181 and 182: where X ~ N(μ X , σ X 2 ) is shor
Page 183 and 184: Using the same critical layers as s
Page 185 and 186: Performance of Levees (Stopbanks) d
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▲▲Figure 3. Typical geometry an
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TABLE 1Damage severity categories (
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(A)(B)▲▲Figure 6. A) Large sand
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(A)(B)▲▲Figure 8. A) Representa
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each of the Waimakariri River and a
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▲ ▲ Figure 2. Horizontal peak g
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only minor damage, mostly to their
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(A)(C)(B)▲▲Figure 5. Ferrymead
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(A)(B)▲▲Figure 7. Damage to sou
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(A)(B)▲▲Figure 11. Settlement o
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(A)(C)(B)▲▲Figure 14. Railway B
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Events Reconnaissance (GEER) Associ
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New PublicationsCanGeoRefThe Americ
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Wednesday, 18 AprilTechnical Sessio
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Verification of a Spectral-Element
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EASTERN SECTIONRESEARCH LETTERSReas
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(A)70°N100°W 60°W70°N(B)100°E1
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Mongolia SCRThe presence or absence
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the small horizontal relative motio
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80°100°120°140°EXPLANATIONBorde
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Chang, K. H. (1997). Korean peninsu
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Wheeler, R. L. (2008). Paleoseismic
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A significant outcome of this study
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TABLE 1 (continued)Earthquakes for
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▲▲Figure 2. Earthquakes used in
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Meeting CalendarM E E T I N GC A L
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201 Plaza Professional Bldg. • El
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Seismological Research Letters (SRL
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Christa von Hillebrandt-Andrade, Pr
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