Here - Stuff

More documents

Recommendations

Info

tunity to investigate the liquefaction mechanism in naturaldeposits. Finally, the re-liquefaction experienced by the city asa result of the recent aftershocks on June 2011 highlights thehigh susceptibility of soil deposits in Christchurch to liquefactionand presents a very challenging problem not only to thelocal residents but to the geotechnical engineering professionas well.ACKNOWLEDGMENTSThe authors would like to acknowledge the other members ofthe NZ-JGS reconnaissance team: Kohji Tokimatsu (TokyoInstitute of Technology, Japan), Ryosuke Uzuoka (TokushimaUniversity, Japan), and Hirofumi Toyota (Nagaoka Universityof Technology, Japan). The insights provided by Michael Pender,Tam Larkin, and Liam Wotherspoon, all of the Universityof Auckland, as well as the assistance of many postgraduatestudents from the University of Auckland and University ofCanterbury, are gratefully acknowledged. Finally, we acknowledgethe New Zealand GeoNet project and its sponsors EQC,GNS Science, and Land Information New Zealand for providingdata used in this paper.REFERENCESBerill, J., H. Avery, M. Dewe, A. Chanerley, N. Alexander, C. Dyer,C. Holden, and B. Fry (2011). The Canterbury AccelerographNetwork (CanNet) and some results from the September 2010M 7.1 Darfield earthquake. In Proceedings of the Ninth PacificConference on Earthquake Engineering, paper no. 181 (CD-ROM).Auckland: New Zealand Society for Earthquake EngineeringBrown, L. J., R. D. Beetham, B. R. Paterson, and J. H. Weeber (1995).Geology of Christchurch, New Zealand. Environmental &Engineering Geoscience 1 (4), 427–488.Brown, L. J., and J. H. Weeber (1992). Geology of the Christchurch UrbanArea. Lower Hutt, New Zealand: Institute of Geological andNuclear Sciences.Christchurch City Council (CCC) (2005). 3.4.5 Earthquake Risk.City Plan Online; http://www.cityplan.ccc.govt.nz (updated 14November 2005).Cubrinovski, M., J. D. Bray, M. Taylor, S. Giorgini, B. Bradley, L.Wotherspoon, and J. Zupan (2011). Soil liquefaction effects in thecentral business district during the February 2011 Christchurchearthquake. Seismological Research Letters 82, 893–904.Cubrinovski, M., R. Green, J. Allen, S. Ashford, E. Bowman, B. Bradley,B. Cox, T. Hutchinson, E. Kavazanjian, R. Orense, M. Pender, M.Quigley, and L. Wotherspoon (2010). Geotechnical reconnaissanceof the 2010 Darfield (Canterbury) earthquake. Bulletin of the NewZealand Society for Earthquake Engineering 43 (4), 243–320.Cubrinovski, M., and R. Orense (2010). 2010 Darfield (New Zealand)earthquake—Impacts of liquefaction and lateral spreading. Bulletinof the International Society for Soil Mechanics and GeotechnicalEngineering 4 (4), 15–23.GeoNet (2010). Strong motion FTP site; ftp://ftp.geonet.org.nz/strong/processed/Proc/2010/09_Darfield_mainshock_extended_pass_band/.GeoNet (2011). Strong motion FTP site; ftp://ftp.geonet.org.nz/strong/processed/Proc/2011/02_Christchurch_mainshock_extended_pass_band/.Green, R. A., C. Wood, B. Cox, M. Cubrinovski, L. Wotherspoon,B. Bradley, T. Algie, J. Allen, A. Bradshaw, and G. Rix (2011).Use of DCP and SASW tests to evaluate liquefaction potential:Predictions vs. observations during the recent New Zealand earthquakes.Seismological Research Letters 82, 927–938.Inada, M. (1960). Interpretation of Swedish weight sounding. Tsuchi-to-Kiso [monthly magazine of the Japanese Geotechnical Society] 8(1), 13–18 (in Japanese).Japanese Standards Association (JSA) (1975). Japanese IndustrialStandards: Method of Swedish Weight Sounding—JIS A 1221(1975), 1995 revision.Natural Hazards Research Platform (NHRP) (2011). Why the 2011Christchurch Earthquake is Considered an Aftershock; http://www.naturalhazards.org.nz.Orense, R., M. Pender, L. Wotherspoon, and M. Cubrinovski (2011).Geotechnical aspects of the 2010 Darfield (New Zealand) earthquake.Invited lecture, Eighth International Conference on UrbanEarthquake Engineering, Tokyo (Japan) (7–8 March 2011).Wotherspoon, L. M., M. J. Pender, and R. P. Orense (2010). Relationshipbetween observed liquefaction at Kaiapoi following the 2010Darfield earthquake and old channels of the Waimakariri River.Submitted to Engineering Geology.Department of Civil and Environmental EngineeringUniversity of AucklandPrivate Bag 92019Auckland 1142 New Zealandr.orense@auckland.ac.nz(R. P. O.)918 Seismological Research Letters Volume 82, Number 6 November/December 2011
Ambient Noise Measurements following the2011 Christchurch Earthquake: Relationshipswith Previous Microzonation Studies,Liquefaction, and NonlinearityMarco MucciarelliMarco MucciarelliBasilicata UniversityINTRODUCTIONFollowing the Christchurch 2011 earthquake, the BasilicataUniversity (Potenza, Italy) organized a field trip to NewZealand mainly to examine structural engineering issues butalso to investigate the similarity between this event and theL’Aquila 2009 quake that struck central Italy. In both casesan event with magnitude slightly above 6 occurred on a blindfault underlying an area inhabited by a population of the orderof hundreds of thousands, killing a few hundred people andseverely damaging the city center, and in both cases a site amplificationstudy was available before the event. At the same timethere were striking differences between the two earthquakesin maximum recorded acceleration, the nonlinear behavior ofsoils, and the occurrence of liquefaction.It was also an opportunity to look at some issues related tothe use of microtremor measurements, in particular:1. to verify if the soil frequencies estimated more than 15years ago by Toshinawa et al. (1997) are a persisting featureor if there were changes following the strong motionsin 2010 and 2011;2. to verify the usefulness of the soil vulnerability index proposedby Nakamura (1996) as a proxy of liquefaction susceptibility;and3. to compare the strong-motion recordings with elasticlimit soil behavior derived from ambient noise, looking forhints of hardening nonlinearity as proposed by Bonilla etal. (2005) and similarity with the observations in L’Aquila(Puglia et al. 2011).PREVIOUS STUDIES AND DATA COLLECTIONIn 1994 the Arthurs Pass Earthquake (M l = 6.6) occurredabout 100 km northwest of Christchurch. The macroseismicintensity was estimated for the city together with local siteamplifications inferred from seismic recordings and microtremors(Toshinawa et al. 1997). The authors found a satisfactorycorrelation among the results of the different techniquesand prepared a microzonation map.As for horizontal-to-vertical spectral ratio (HVSR) analysisof microtremors, Toshinawa et al. (1997) collected three setsof 40-sec-long samples at each site on a 1 by 1 km grid. Theyfound that the H/V spectral ratio of microtremors was wellcorrelated to the ground motion characteristics during earthquakesrecorded at a seismic array deployed within the city andalso correlated with the local geology. The outcropping lithologyof the Christchurch area (Brown and Weeber 1992) iscomposed of:1. Volcanic rock, in the southern part of the city.2. Holocene marine dunes, in the vicinity of the coast.3. Alluvial sand and silt deposits from the estuarine area tothe center of the city, where swamps and lagoons weredrained to reclaim land.4. Alluvial gravel area, in the westernmost part of the city.5. Transition area, with alternating deposits, located betweenthe estuarine and gravel areas.The soil fundamental frequency had higher values in the westerngravel area, starting from 5 Hz and decreasing down to 1Hz proceeding eastward in the transition area and in the sandand silt alluvium beneath the city center. The volcanic rock atthe south returned a flat response and no clear peak was identifiedin the dune area near the ocean coastline.During our field trip, we devoted three days to microtremormeasurements. It was possible to perform 43 measurements, aslisted in Table 1. We also collected 12 recordings as close aspossible to accelerometric stations that recorded the February2011 event, while the others were taken in the most damagedareas but with an effort to obtain good spatial coverage (Figure1). The data were sampled at 128 Hz using a digital threecomponenttromometer (Micromed Tromino) for an acquisitionlength of at least 12 minutes. The data were then filtered,tapered, transformed in frequency domain, smoothed with atriangular filter (n = 5), and finally averaged between horizontalcomponents and among 20-sec subsets using the geometricmean. Almost all the recordings returned HVSR peaks thatpassed the ensemble of tests proposed by the SESAME project(Chatelain et al. 2008).doi: 10.1785/gssrl.82.6.919Seismological Research Letters Volume 82, Number 6 November/December 2011 919
Page 1:
Volume 82, Number 6 November/Decemb
Page 7:
News and Notes (continued)Nominatio
Page 11:
Preface to the Focused Issue on the
Page 14 and 15:
TABLE 1Peak ground acceleration (PG
Page 16 and 17:
▲▲Figure 2. A) Sketch of the
Page 18 and 19:
▲▲Figure 4. A) Adopted moment r
Page 20 and 21:
▲▲Figure 7. As in Figure 6 but
Page 22 and 23:
▲ ▲ Figure 8. Misfit parameters
Page 24 and 25:
▲ ▲ Figure 10. Spatial variabil
Page 26 and 27:
▲ ▲ Figure 12. Standard spectra
Page 28 and 29:
Quigley, M., R. Van Dissen, P. Vill
Page 30 and 31:
slip on a 59-degree striking fault
Page 32 and 33:
▲▲Figure 4. Convergence of inve
Page 34 and 35:
observations and other source studi
Page 36 and 37:
-42. 5-43. 0-43. 5-44. 0-44. 5-43.2
Page 38 and 39:
“Product CSK © ASI, (ItalianSpac
Page 40 and 41:
TABLE 2Solutions for fault location
Page 42 and 43:
-43.45(A)degrees N-43.50-43.552.52.
Page 44 and 45:
is still a good fit to the horizont
Page 46 and 47:
Coulomb Stress Change Sensitivity d
Page 48 and 49:
mation takes on a larger strike-sli
Page 50 and 51:
P 9.4267BLDU45P 20.1213CASY39P 2.62
Page 52 and 53:
ERMJNUMAJOINUJHJ2CBIJMIDWJOWYHNBTPU
Page 54 and 55:
(A)6.146.13(B)6.246.36Misfit6.156.1
Page 56 and 57:
(A)(B)(C)(D)▲▲Figure 10. The co
Page 58 and 59:
(A)(B)(C)(D)▲▲Figure 12. The co
Page 60 and 61:
Luo, Y., Y. Tan, S. Wei, D. Helmber
Page 62 and 63:
−44˚00' −43˚00'4-Sep-2010Mw 7
Page 64 and 65:
TABLE 1Pairs of SAR imagery used in
Page 67 and 68:
Depth (km)Coulomb Stress Change(bar
Page 69 and 70:
Crippen, R. E. (1992). Measurement
Page 71 and 72:
AlpineFaultHope Fault38 mm/yr0+ +-1
Page 73 and 74:
σ 1dσ 3Nuσ 3CM w 7.1dw 6.2u70°M
Page 75 and 76:
Right-lateral Faults(A) Range Front
Page 77 and 78:
DISCUSSIONThe 2010-2011 Canterbury
Page 79 and 80:
Large Apparent Stresses from the Ca
Page 81 and 82:
▲ ▲ Figure 2. Observed vs. pred
Page 83 and 84:
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 and 136: Case StudyKey ParametersTABLE 1Key
Page 137 and 138: ▲ ▲ Figure 9. Representative bu
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: ▲▲Figure 17. A trench in a resi
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
Page 187 and 188: ▲▲Figure 3. Typical geometry an
Page 189 and 190: TABLE 1Damage severity categories (
Page 191 and 192: (A)(B)▲▲Figure 6. A) Large sand
Page 193 and 194: (A)(B)▲▲Figure 8. A) Representa
Page 195 and 196: each of the Waimakariri River and a
Page 197 and 198: ▲ ▲ Figure 2. Horizontal peak g
Page 199 and 200: only minor damage, mostly to their
Page 201 and 202: (A)(C)(B)▲▲Figure 5. Ferrymead
Page 203 and 204: (A)(B)▲▲Figure 7. Damage to sou
Page 205 and 206: (A)(B)▲▲Figure 11. Settlement o
Page 207 and 208: (A)(C)(B)▲▲Figure 14. Railway B
Page 209 and 210: Events Reconnaissance (GEER) Associ
Page 211 and 212: New PublicationsCanGeoRefThe Americ
Page 213 and 214: Wednesday, 18 AprilTechnical Sessio
Page 215 and 216:
Verification of a Spectral-Element
Page 217 and 218:
EASTERN SECTIONRESEARCH LETTERSReas
Page 219 and 220:
(A)70°N100°W 60°W70°N(B)100°E1
Page 221 and 222:
Mongolia SCRThe presence or absence
Page 223 and 224:
the small horizontal relative motio
Page 225 and 226:
80°100°120°140°EXPLANATIONBorde
Page 227 and 228:
Chang, K. H. (1997). Korean peninsu
Page 229 and 230:
Wheeler, R. L. (2008). Paleoseismic
Page 231 and 232:
A significant outcome of this study
Page 233 and 234:
TABLE 1 (continued)Earthquakes for
Page 235 and 236:
▲▲Figure 2. Earthquakes used in
Page 237 and 238:
Meeting CalendarM E E T I N GC A L
Page 239 and 240:
201 Plaza Professional Bldg. • El
Page 241 and 242:
Seismological Research Letters (SRL
Page 243 and 244:
Christa von Hillebrandt-Andrade, Pr
show all

Here - Stuff

Create successful ePaper yourself

Delete template?

Save as template?