Near-source strong ground motions observed in the 22 February 2011 Christchurch earthquake
This manuscript provides a critical examination of the ground motions recorded in the near-source region resulting from the 22 February 2011 Christchurch earthquake. Particular attention is given to reconciling the observed spatial distribution of ground motions in terms of physical phenomena related to source, path and site effects. The large number of near-source observed strong ground motions show clear evidence of: forward-directivity, basin generated surface waves, liquefaction and other significant nonlinear site response. The pseudo-acceleration response spectra (SA) amplitudes and significant duration of strong motions agree well with empirical prediction models, except at long vibration periods where the influence of basin-generated surface waves and nonlinear site response are significant and not adequately accounted for in empirical SA models. Pseudo-acceleration response spectra are also compared with those observed in the 4 September 2010 Darfield earthquake and routine design response spectra used in order to emphasise the amplitude of ground shaking and elucidate the importance of local geotechnical characteristics on surface ground motions. The characteristics of the observed vertical component accelerations are shown to be strongly dependent on source-to-site distance and are comparable with those from the 4 September 2010 Darfield earthquake, implying the large amplitudes observed are simply a result of many observations at close distances rather than a peculiar source effect.
New Zealand Police. (2011) "Christchurch earthquake: List of deceased".
DeMets, C., Gordon, R.G., Argus, D.F. and Stein, S. (1994) "Effect of recent revisions to the geomagnetic time scale on estimates of current plate motion". Geophysical Research Letters; 21 2191-2194. DOI: https://doi.org/10.1029/94GL02118
Sutherland, R., Berryman, K. and Norris, R. (2006) "Quaternary slip rate and geomorphology of the Alpine fault: Implications for kinematics and seismic hazard in southwest New Zealand". Geological Society of America Bulletin; 118 464-474. DOI: https://doi.org/10.1130/B25627.1
Stirling, M.W., Gerstenberger, M., Litchfield, N., McVerry, G.H., Smith, W.D., Pettinga, J.R. and Barnes, P. (2007) "Updated probabilistic seismic hazard assessment for the Canterbury region". 58.
NZSEE. (2010) "Special Issue: Preliminary observations of the 2010 Darfield (Canterbury) Earthquakes". Bulletin of the New Zealand Society for Earthquake Engineering; 43(4): 215-439.
Beavan, J., Fielding, E.J., Motagh, M., Samsonov, S. and Donnelly, B.S. (2011) "Fault location and slip distribution of 22 February 2011 Mw 6.3 Christchurch, New Zealand, earthquake for geodetic data". Seismological Research Letters, Focused Issue on the 2011 Christchurch New Zealand Earthquake. DOI: https://doi.org/10.1785/gssrl.82.6.789
Somerville, P.G., Ikikura, K., Graves, R.W., Sawada, S., Wald, D., Abrahamson, N.A., Iwasaki, Y., Kagawa, T., Smith, N. and Kowada, A. (1999) "Characterizing crustal earthquake slip models for the prediction of strong ground motion". Seismological Research Letters; 70(1): 59-80. DOI: https://doi.org/10.1785/gssrl.70.1.59
Brown, L.J. and Weeber, J.H. (1992) "Geology of the Christchurch urban area", Geological and Nuclear Sciences 110.
NZS 1170.5. (2004) "Structural design actions, Part 5: Earthquake actions - New Zealand". Standards New Zealand: Wellington, New Zealand, 82.
Bradley, B.A. (2010) "NZ-specific pseudo-spectral acceleration ground motion prediction equations based on foreign models" Report No.2010-03, Department of Civil and Natural Resources Engineering, University of Canterbury: Christchurch, New Zealand. 324.
Aoi, S., Kunugi, T. and Fujiwara, H. (2008) "Trampoline Effect in Extreme Ground Motion". Science; 322(5902): 727-730. DOI: https://doi.org/10.1126/science.1163113
Yamada, M., Mori, J. and Heaton, T. (2009) "The Slapdown Phase in High-acceleration Records of Large Earthquakes". Seismological Research Letters; 80(4): 559-564. DOI: https://doi.org/10.1785/gssrl.80.4.559
Bradley, B.A. (2012) "A critical analysis of strong ground motions observed in the 4 September 2010 Darfield earthquake". Soil Dynamics and Earthquake Engineering; (submitted). DOI: https://doi.org/10.1016/j.soildyn.2012.06.004
Aagaard, B.T., Hall, J.F. and Heaton, T.H. (2004) "Effects of Fault Dip and Slip Rake Angles on Near-Source Ground Motions: Why Rupture Directivity Was Minimal in the 1999 Chi-Chi, Taiwan, Earthquake". Bulletin of the Seismological Society of America; 94(1): 155-170. DOI: https://doi.org/10.1785/0120030053
Shahi, S.K. and Baker, J.W. (2011) "An Empirically Calibrated Framework for Including the Effects of Near- Fault Directivity in Probabilistic Seismic Hazard Analysis". Bulletin of the Seismological Society of America; 101(2): 742-755. DOI: https://doi.org/10.1785/0120100090
Hicks, S.R. (1989) "Structure of the Canterbury Plains, New Zealand from gravity modelling", Geophysics Division, Department of Science and Industrial Research: Wellington.
Choi, Y., Stewart, J.P. and Graves, R.W. (2005) "Empirical Model for Basin Effects Accounts for Basin Depth and Source Location". Bulletin of the Seismological Society of America; 95(4): 1412-1427. DOI: https://doi.org/10.1785/0120040208
Chiou, B.S.J. and Youngs, R.R. (2008) "An NGA Model for the average horizontal component of peak ground motion and response spectra". Earthquake Spectra; 24(1): 173-215. DOI: https://doi.org/10.1193/1.2894832
Cubrinovski, M., Green, R.A., Allen, J., Ashford, S.A., Bowman, E., Bradley, B.A., Cox, B., Hutchinson, T.C., Kavazanjian, E., Orense, R.P., Pender, M., Quigley, M. and Wotherspoon, L. (2010) "Geotechnical reconnaissance of the 2010 Darfield (Canterbury) earthquake". Bulletin of the New Zealand Society for Earthquake Engineering; 43(4): 243-320.
Silva, W.J. (1997) "Characteristics of vertical strong ground motions for applications to engineering design, FHWA/NCEER Workshop on the National Representation of Seismic Ground Motion for New and Existing Highway Facilities, Burlingame, CA, Proceedings" Earthquake Spectra, National Center for Earthquake Engineering Research: Buffalo, New York.
Bozorgnia, Y. and Campbell, K.W. (2004) "The vertical-to-horizontal response spectral ratio and tentative procedures for developing simplified V/H and vertical design spectra". Journal of Earthquake Engineering; 8(2): 175-207. DOI: https://doi.org/10.1080/13632460409350486
Chiou, B., Youngs, R., Abrahamson, N. and Addo, K. (2010) "Ground-Motion Attenuation Model for Small-To-Moderate Shallow Crustal Earthquakes in California and Its Implications on Regionalization of Ground-Motion Prediction Models". Earthquake Spectra; 26(4): 907-926. DOI: https://doi.org/10.1193/1.3479930
Pinheiro, J., Bates, D.M., DebRoy, S., Sarkar, D. and the R Core team. (2008) "nlme: linear and nonlinear mixed effects models".
Abrahamson, N.A. and Youngs, R.R. (1992) "A stable algorithm for regression analyses using the random effects model". Bulletin of the Seismological Society of America; 82(1): 505-510.
Bradley, B.A. (2011) "Correlation of significant duration with amplitude and cumulative intensity measures and its use in ground motion selection". Journal of Earthquake Engineering; (in press). DOI: https://doi.org/10.1080/13632469.2011.557140
Bommer, J.J., Stafford, P.J. and Alarcon, J.E. (2009) "Empirical Equations for the Prediction of the Significant, Bracketed, and Uniform Duration of Earthquake Ground Motion". Bulletin of the Seismological Society of America; 99(6): 3217-3233. DOI: https://doi.org/10.1785/0120080298
Cubrinovski, M., Bray, J.D., Taylor, M.L., Giorgini, S., Bradley, B.A., Wotherspoon, L. and Zupan, J. (2011) "Soil liquefaction effects in the Central Business District during the February 2011 Christchurch earthquake". Seismological Research Letters, Focused Issue on the 2011 Christchurch New Zealand Earthquake. DOI: https://doi.org/10.1785/gssrl.82.6.893
Copyright (c) 2011 Brendon A. Bradley, Misko Cubrinovski
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