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Quigley, M., R. Van Dissen, P. Villamor, N. Litchfield, D. Barrell, K.Furlong, T. Stahl, B. Duffy, E. Bilderback, D. Noble, D. Townsend,J. Begg, R. Jongens, W. Ries, J. Claridge, A. Klahn, H. Mackenzie,A. Smith, S. Hornblow, R. Nicol, S. Cox, R. Langridge, and K.Pedley (2010). Surface rupture of the Greendale fault during theM W 7.1 Darfield (Canterbury) earthquake, New Zealand: Initialfindings. Bulletin of the New Zealand Society for EarthquakeEngineering 43, 236–242.Reyners, M., and H. Cowan (1993). The transition from subduction tocontinental collision: Crustal structure in the North Canterburyregion, New Zealand. Geophysical Journal International 115,1,124–1,136.Scherwath, M., T. Stern, F. Davey, D. Okaya, W. S. Holbrook, R.Davies, and S. Kleffmann (2003). Lithospheric structure acrossoblique continental collision in New Zealand from wide-angle Pwave modeling. Journal of Geophysical Research 108 (B12), 2,566;doi:10.1029/2002JB002286.Semmens, S., N. D. Perrin, G. Dellow, and R. Van Dissen (2011).NZS 1170.5:2004 Site subsoil classification of WellingtonCity. Proceedings of the Ninth Pacific Conference on EarthquakeEngineering, Building an Earthquake-Resilient Society, 14–16April 2011, Auckland, New Zealand, paper no. 7. Auckland, NewZealand, 9PCEE.Smerzini, C., R. Paolucci, and M. Stupazzini (2011). Comparison of3D, 2D and 1D numerical approaches to predict long period earthquakeground motion in the Gubbio plain, central Italy. Bulletinof Earthquake Engineering (June) 1–23; doi:10.1007/s10518-011-9289-8.Stupazzini, M., R. Paolucci, and H. Igel (2009). Near-fault earthquakeground motion simulation in the Grenoble Valley by a high performancespectral element code. Bulletin of the Seismological Society ofAmerica 99, 286–301.Tonkin and Taylor Ltd. (2010). Darfield Earthquake 4 September 2010,Geotechnical Land Damage Assessment & Reinstatement Report.Earthquake Commission. Stage 1 Report for the New ZealandEarthquake Commission. Christchurch, New Zealand: Tonkin &Taylor Ltd.Department of Structural EngineeringPolitecnico di MilanoPiazza Leonardo da Vinci, 32Milano 20133 Italyguidotti@stru.polimi.it(R. G.)782 Seismological Research Letters Volume 82, Number 6 November/December 2011
Kinematic Source Model of the 22 February2011 M w 6.2 Christchurch Earthquake UsingStrong Motion DataCaroline HoldenCaroline HoldenGNS ScienceINTRODUCTIONThe Canterbury earthquake sequence began in September2010 with the Mw 7.1 (source: GeoNet catalog, http://geonet.org.nz/canterbury-quakes/) Darfield earthquake that rupturedthe previously unknown 40-km-long Greendale fault 30 kmwest of Christchurch (Gledhill et al. 2011). Extreme groundaccelerations as high as 1.8 g near the epicenter were recorded.The event caused intense liquefaction in the eastern suburbs ofChristchurch as well as closer to downtown, near the courseof the Avon River. The Darfield earthquake was followed bya major aftershock on 22 February local time (21 FebruaryUTC) of magnitude Mw 6.2 (source: GeoNet), but Me 6.7(source: USGS, http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usb0001igm/neic_b0001igm_e.php). Thisearthquake was centred only a few kilometers south of theChristchurch city center. Extremely high accelerations (as highas 2.2 g) were also recorded near the epicenter (Kaiser, Beniteset al. 2011). In addition to the extreme liquefaction seen afterthe Darfield earthquake, this event also caused landslides,large rockfalls, widespread damage to earthquake-risk buildingsin Christchurch, and, most tragically, about 180 casualties.Another large aftershock of Mw 6.0 (source: GeoNet), butwith Me 6.7 (source: USGS), subsequently occurred on 13 Junelocal time (12 June UTC) just a few kilometers south of theFebruary event, causing further damage, landslides, rockfalls,and liquefaction.Following the Darfield earthquake, the GeoNet network(New Zealand National Hazard Monitoring Network) and itsregional component the CanNet network (Berrill et al. 2011)was supplemented by the deployment of 13 additional strongmotion instruments regionally (and another nine following theFebruary earthquake). We used this dense network of strongmotion instruments to constrain the source kinematics of theFebruary event. We present the inversion scheme and discussits limitations. These results are preliminary, since more thoroughdata processing is needed; however, they already provide akey model that will help in understanding the sequence of largeaftershocks that has developed near Christchurch. This work isstrongly dependent on other studies by Beavan et al. 2011, page789 of this issue; Fry et al. 2011; Bannister et al. 2011, page839 of this issue; Sibson et al. 2011, page 824 of this issue;and Kaiser, Benites et al. (2011).THE STRONG MOTION DATASETAt the time of the February earthquake there were 14 strongmotion GeoNet sites, from both the national and the regionalCanterbury network CanNet, within 20 km of the epicenter(Figure 1). However, there were strong site effects at stationsPRPC, SHLC, and HPSC, each of which sits on very softground and suffered intense liquefaction from the earthquake;therefore those three were excluded, leaving 11 stations to beincluded in the inversion scheme. The source-station distanceranges from 2 to 20 km.All of the recordings used in this study suffered from siteeffects to some degree. Stations on rock sites are found only onthe hills of Banks Peninsula (south of Christchurch) wherestrong topographic effects are the likely cause of an intensedamage pattern over the hills of Banks Peninsula as describedby Hancox et al. (2011). Stations on the plains suffered fromvery soft shallow layers inducing non-linear amplificationsand extreme phenomena such as liquefaction and trampolineeffects (Fry et al. 2011). Unfortunately, ground conditionswithin Christchurch are highly variable and will require furtherstudies for stations in this region to be included in themodeling (Kaiser, Holden et al. 2011).For our inversion study, the acceleration data has beenintegrated into velocity and filtered using a Butterworth bandpassfilter from 0.1 to 1.0 Hz. Since we are interested in thepolarity and amplitude of the first onset we used a causal filter.We applied the same filter to observed and synthetic data. Thedata from the CanNet stations were rotated from their originalorientation to north-south and east-west components.INVERSION SCHEMEWe inverted three-component data for 11 well-distributedstrong motion stations within 20 km of the epicenter. We useda fixed fault plane geometry of strike 59 and dip 67 as definedby Beavan et al. 2011 (page 789 of this issue) since processedInSAR data clearly shows deformation fringes resulting fromdoi: 10.1785/gssrl.82.6.783Seismological Research Letters Volume 82, Number 6 November/December 2011 783
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 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
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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(
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Fine-scale Relocation of Aftershock
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−43.25°OXZ0 10 20km−43.5°−4
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A’0 km 4 8−43.5°B’B−43.6°
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REFERENCESAvery, H. R., J. B. Berri
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▲ ▲ Figure 2. A) shows three-co
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▲ ▲ Figure 4. Vertical accelera
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0.8PRPC Z0.40Normalized (Max PGA +
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Near-source Strong Ground MotionsOb
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(A)Magnitude, M w876542009 NZdataba
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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
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REFERENCESAagaard, B. T., J. F. Hal
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▲ ▲ Figure 1. Shear-wave veloci
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Spectral Acceleration (0.3 s), (g)I
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Spectral Acceleration (3 s), (g)In[
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TABLE 1Mean (μ LLH ) and standard
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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
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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▲
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Comparison of Liquefaction Features
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(A)(B)▲▲Figure 2. A) Simplified
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(A)Acceleration (Gal)6004002000-200
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(A)(B)▲▲Figure 7. Distribution
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(A)(B)▲▲Figure 10. Damage to a
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(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
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▲▲Figure 8. Comparison between
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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
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Using the same critical layers as s
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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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