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ERMJNUMAJOINUJHJ2CBIJMIDWJOWYHNBTPUB SSLB YULBNACB TATO YOJHKPSGUMOPATSWAKEKWAJJOHNKIPQIZDAVMANURABLXMASKKM LDMSBMKSMKUM IPMBTDF KOMPSIUGMKAPIPMGCOENMTNCCTTAO AKNRA QISWRABHNRAFIRARPPTFTAOEXMISMBWAWRKACOCOGIRLMORW KMBLBLDUMUNBBOOCASYVNDA SBAPAFQSPAMAWLCOPLCACRZFPMSAEFITRQAHOPE▲ ▲ Figure 6. Seismic stations used in the inversion of fault parameters of the 2011 Christchurch earthquake. These stations are chosenbased on their signal-to-noise ratio (SNR) and azimuthal coverage.tion. For each candidate depth and source duration, we alsoplot its best fitting focal mechanisms and magnitudes in Figure8, to show the trade-off between magnitude and other sourceparameters. Obviously, the earthquake magnitude decreasesas depth increases, as expected from the free surface effects asdiscussed by Dahlen and Tromp (1998). If depth = 12 km (asdetermined in the Global CMT), the magnitude will be aboutM w 6.15, which is close to the M w 6.1 in the GCMT catalog.Due to the trade-off between depth and focal mechanism forshallow events, the GCMT’s focal mechanism may also besomewhat biased. We conclude that teleCAP provides higherresolutionsource parameters for the 2011 Christchurch earthquake.However, it should be noted that teleCAP assumes adouble-couple point source, as do most other approaches, so itcannot distinguish between the fault plane and auxiliary faultplane. The first three days’ aftershock distribution of the 2011Christchurch earthquake shows a clear linear trend from EENto WWS (Figure 1), which prefers the fault plane 52°/61°/128°.In the following discussion we will use only this fault plane.Epicenter location is another important source parameter thatwill greatly affect the computation of Coulomb stress change.In this paper, we use the epicenter location from New ZealandGeoNet, which is based on data from a dense local seismic networkand is presumably accurate.COMPUTATION OF COULOMB STRESS FORVARIOUS MAINSHOCK SOURCE MODELS ANDRECEIVING FAULT GEOMETRIESBased on the Coulomb failure criterion (Jaeger et al. 2007,475) and the theory of elastic dislocation (Okada 1992), wecalculate the coseismic Coulomb failure stress change (Δσ f )caused by the mainshock for different mainshock slip modelsand for different receiving fault geometries. Following King etal. (1994), Δσ f is given by Δσ f = Δτ s – μ′Δσ n , where Δτ s andΔσ n are the changes in shear and normal stress, respectively,due to the mainshock, and μ′ is the apparent coefficient of friction.<strong>Here</strong> we use the rock mechanics sign convention in whichcompressive is positive.In this study, we use the lithosphere model of dislocationsources embedded in an elastic multilayered half space (Wanget al. 2003, 2006) and adopt the program PSGRN/PSCMP(Wang et al. 2006) to compute the static Coulomb stresschange produced by the mainshock. Since the influence fromthe curvature of Earth’s free surface is small for this local study(Xiong et al. 2010), the Earth surface is treated as flat in ourmodel. The parameters of our multilayered model in Table 1are based on Crust 2.0. A moderate value of apparent coefficientof friction μ′ = 0.4 is used in our calculation (King et al.806 Seismological Research Letters Volume 82, Number 6 November/December 2011
P VSHP VSHP VSHP VSHMIDWTRQAPAFMBWA72.1/9.284.7/139.765.3/224.649.1/279.6−6.00553.03−3.00−1.00524.35−5.00928989798592JOHNEFIMUNWRKA62.2/19.375.3/150.145.3/265.140.5/282.4−5.00−3.00−4.00399.08−5.00361.52837593959687AFIPMSABLDUPSI32.5/29.063.1/156.345.7/267.080.2/283.2−3.00−1.00514.09−5.00400.43−5.00601.1680659491969672KIPHOPEMORWUGM70.1/29.079.2/163.147.0/268.464.6/284.0−5.00−2.00−4.00409.05−5.00516.71895992969385XMASQSPAKMBLBTDF52.8/38.746.5/180.041.5/269.675.9/285.8−3.00450.4015.00−4.00372.16−4.00579.4989736694968990RARSBACOCOIPM32.0/54.534.4/182.271.5/270.780.0/286.0−2.0015.00334.66−5.00−4.00601.04914394939379PPTFVNDAGIRLKOM41.0/62.834.3/184.252.1/273.976.1/286.2−1.00374.7015.00332.78−4.00442.52−5.00582.838791689091949194TAOEMAWBBOOKUM53.6/64.257.2/205.430.5/278.280.8/286.3454.762.00492.56−3.00298.02−5.00603.3185416692719475LCOCASYXMISKSM87.3/128.440.0/213.866.3/278.371.4/290.8−2.00640.332.00362.18−5.00526.55−4.00557.529283458296819287PLCACRZFXMIKNRA78.5/136.276.1/217.766.3/278.446.5/292.8−2.00595.84−1.00585.42−5.00526.51402.6187827879968087P VSHP VSHP VSHP VSHSBMCTAPMGHNR70.9/293.032.2/308.340.7/319.235.8/338.1−4.00555.40−3.00309.63−4.00−5.00886388718785KAPICTAOJOWERM60.3/293.732.2/308.381.1/320.789.3/338.4−4.00309.61−4.00−4.00648.518971949194WRABCOENMANUPATS39.7/294.138.9/310.347.1/324.351.9/341.7−5.00−4.00354.53−5.00407.62−5.00438.9195948787648872MTNTPUBJNUWAKE47.0/297.882.0/312.985.4/325.862.9/353.6−5.00407.95−5.00610.08−5.00625.06−6.00502.619089958294768966KKMSSLBGUMOKWAJ71.0/298.782.2/313.462.4/329.252.4/353.6−4.00554.84−5.00611.19−6.00−6.00437.9985749879908581QISYULBRABL35.9/299.281.7/313.543.3/329.3LDM−4.0096NACB−5.0089609.6781INU−5.0085FM 174 46 42 Mw 6.3068.8/299.982.2/314.185.1/331.4−3.00−5.00612.09−5.00625.357795909167QIZYHNBCBIJ84.8/302.382.7/314.375.8/332.1−3.00628.19−5.00613.69−8.009291929091DAVTATOJHJ266.0/307.282.9/314.582.1/332.6−7.00−5.00−6.00879393HKPSYOJMAJO84.8/307.581.7/315.485.8/332.8−4.00627.87−5.00608.63−5.009087888796▲ ▲ Figure 7. Best teleseismic waveform fitting and the corresponding focal mechanism (strike/dip/rake = 174°/46°/42°) and magnitude(M w 6.3). Black is the data and red is the synthetic. The red crosses on the focal mechanism beach ball show the locations of stations.1994), and parameter sensitivity will be discussed. To show theinfluence of the uncertainty of focal depth, we calculate the Δσ fcaused by the mainshock on several horizontal planes at 2, 5,10, and 15 km depths, respectively, each of which consists of101 × 101 grid points. In the next several subsections, we willshow the Δσ f results for these different cases and discuss theirvariability. It should be noted that the effect of viscoelasticrelaxation is not taken into account here. Because of the shorttime interval between the two events, its influence is believedto be relatively small, compared with the uncertainties of otherparameters above. More accurate results can be achieved bytaking this effect into account in the future.Coulomb Stress Change Caused by Different MainshockSlip ModelsThe selection of an appropriate mainshock slip model is importantfor the Δσ f distribution. Figure 9 displays the Δσ f distributionfor the four slip models discussed previously. In all cases,the slip models have a strong influence on the Δσ f distributionalong the Greendale fault in the near field. For example, theGreendale fault lies completely within a stress shadow in Figure9A, but there are some parts significantly loaded (>1MPa) usingthe other three models in Figure 9B–D. However, these differentslip models cause no significant difference in the far field. Atthe eastern and western ends of the Greendale fault, the stresschanges more than 0.01 MPa caused by each model, and the Δσ fdistributions, are very similar. In summary, it can be inferredthat a uniform slip model can explain the main features of theΔσ f distribution in the far field; the more complicated slip modelsmake the Δσ f distribution heterogeneous in the near-fieldalong the fault. At the hypocenter of the 2011 Christchurchearthquake, the Δσ f are 0.013, 0.044, 0.033, and 0.053 MPafor the four different slip models, respectively—all above 0.01MPa, the presumed threshold value for earthquake triggering.Seismological Research Letters Volume 82, Number 6 November/December 2011 807
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 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.
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(A)(B)Spectral Acc, Sa (g)North/Wes
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Vertical-to-horizontal PGA ratio543
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(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
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ings and the Modified Takeda-Slip M
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high, but there were no buildings d
Page 127 and 128:
REFERENCES▲▲Figure 8. Heavily d
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(A)(B)(C)(D)(E)▲▲Figure 1. A) M
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(A) (B) (C)▲ ▲ Figure 3. A) Typ
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(A) (B) (C)▲ ▲ Figure 4. A) Typ
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Case StudyKey ParametersTABLE 1Key
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▲ ▲ Figure 9. Representative bu
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Soil Liquefaction Effects in the Ce
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▲ ▲ Figure 2. Representative su
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Location of structures illustrated
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Shading indicates areaover which pr
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1.8 deg15 cmGround cracking due to
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30 cm17 cm30 cmFoundation beam▲
Page 151 and 152:
Comparison of Liquefaction Features
Page 153 and 154:
(A)(B)▲▲Figure 2. A) Simplified
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(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
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▲▲Figure 17. A trench in a resi
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Ambient Noise Measurements followin
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▲▲Figure 1. Location of the noi
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▲▲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
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▲ ▲ Figure 2. Aerial image of C
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(A)(B)▲▲Figure 4. DCP test bein
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▲▲Figure 7. SASW setup at a sit
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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
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(A)(B)▲▲Figure 8. A) Representa
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each of the Waimakariri River and a
Page 197 and 198:
▲ ▲ Figure 2. Horizontal peak g
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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
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(A)(B)▲▲Figure 11. Settlement o
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(A)(C)(B)▲▲Figure 14. Railway B
Page 209 and 210:
Events Reconnaissance (GEER) Associ
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New PublicationsCanGeoRefThe Americ
Page 213 and 214:
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
Page 223 and 224:
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
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
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