Earthquake ground shaking hazard assessment for the Lower Hutt and Porirua areas, New Zealand
Geographic variations in strong ground shaking expected during damaging earthquakes impacting on the Lower Hutt and Porirua areas are identified and quantified. Four ground shaking hazard zones have been mapped in the Lower Hutt area, and three in Porirua, based on geological, weak motion, and strong motion inputs. These hazard zones are graded from 1 to 5. In general, Zone 5 areas are subject to the greatest hazard, and Zone 1 areas the least. In Lower Hutt, zones 3 and 4 are not differentiated and are referred to as Zone 3-4. The five-fold classification is used to indicate the range of relative response.
Zone 1 areas are underlain by bedrock. Zone 2 areas are typically underlain by compact alluvial and fan gravel. Zone 3-4 is underlain, to a depth of 20 m, by interfingered layers of flexible (soft) sediment (fine sand, silt, clay, peat), and compact gravel and sand. Zone 5 is directly underlain by more than 10 m of flexible sediment with shear wave velocities in the order of 200 m/s or less.
The response of each zone is assessed for two earthquake scenarios. Scenario 1 is for a moderate to large, shallow, distant earthquake that results in regional Modified Mercalli intensity V-VI shaking on bedrock. Scenario 2 is for a large, local, but rarer, Wellington fault earthquake. The response characterisation for each zone comprises: expected Modified Mercalli intensity; peak horizontal ground acceleration; duration of strong shaking; and amplification of ground motion with respect to bedrock, expressed as a Fourier spectral ratio, including the frequency range over which the most pronounced amplification occurs. In brief, high to very high ground motion amplifications are expected in Zone 5, relative to Zone 1, during a scenario 1 earthquake. Peak Fourier spectral ratios of 10-20 are expected in Zone 5, relative to Zone 1, and a difference of up to three, possibly four, MM intensity units is expected between the two zones. During a scenario 2 event, it is anticipated that the level of shaking throughout the Lower Hutt and Porirua region will increase markedly, relative to scenario 1, and the average difference in shaking between each zone will decrease.
Berryman, K.R. 1990, "Late Quaternary movement on the Wellington Fault in the Upper Hutt area, New Zealand", New Zealand Journal of Geology and Geophysics 33: 257-270. DOI: https://doi.org/10.1080/00288306.1990.10425683
Borcherdt, R.D. 1991, "On the observation, characterization, and predictive GIS mapping of strong ground shaking for seismic zonation: a case study in the San Francisco Bay region, California", In Proceedings, Pacific Conference on Earthquake Engineering. Auckland, New Zealand: v. 1. p. 1-24.
Borcherdt, R.D. 1985, "Predicting earthquake ground motion: an introduction", In Evaluating Earthquake Hazards in the Los Angeles Region - An Earth-Science Perspective. U.S. Geological Survey Professional Paper 1360: 93-99.
Borcherdt, R.D., Glassmoyer, G. 1992, "On the characteristics of local geology and their influence on ground motions generated by the Loma Prieta earthquake in the San Francisco Bay region, California", Bulletin of the Seismological Society of America 82: 603-641.
Borcherdt, R., Wentworth, C.M., Janssen, A., Fumal, T., Gibbs, J. 1991, "Methodology for predictive GIS mapping of special study zones for strong ground shaking in the San Francisco Bay region, CA", In Proceedings, Fourth International Conference on Seismic Zonation. Stanford, California: Vol. 3. p. 545-552.
Borcherdt, R.D., Glassmoyer, G. 1990, "Local geology and its influence on strong ground motion generated by the Loma Prieta earthquake of October 17, 1989", In Proceedings, Putting the Pieces Together, The Loma Prieta Earthquake One Year Later. San Francisco.
Borcherdt, R., Glassmoyer, G., Andrews, M., Cranswick, E. 1989, "Effects of site conditions on ground motion and damage", In Armenia Earthquake Reconnaissance report. Earthquake Spectra, special supplement: 23-42.
Borcherdt, R.D., Gibbs, J.F. 1976, "Effects of local geological conditions in the San Francisco Bay region on ground motions and the intensities of the 1906 earthquake", Bulletin Seismological Society of America 66: 465-500.
Campbell, K.W. 1981, "Near-source attenuation of peak horizontal acceleration", Bulletin of the Seismological Society of America 71: 2039-2070.
Dellow, G.D., Read, S.A.L., Begg, J.G., Van Dissen, R.J., Perrin, N.D. 1992, "Distribution of geological materials in Lower Hutt, and Porirua, New Zealand: a component of a ground shaking hazard assessment", Bulletin of the New Zealand National Society for Earthquake Engineering (this volume). DOI: https://doi.org/10.5459/bnzsee.25.4.332-344
Dowrick, D.J., Sritharan, S. 1992, "Attenuation of peak ground accelerations in some recent New Zealand earthquakes", Bulletin of the New Zealand National Society for Earthquake Engineering, Vol.25 No.4, pp
Eiby, G.A. 1980, "The Marlborough earthquakes of 1848", DSIR Bulletin 225.
Evernden, J.F., Thomson, J.M. 1988, "Predictive model for important ground motion parameters associated with large and great earthquakes", U.S. Geological Survey Bulletin 1838.
Fukushima, Y., Tanaka, T. 1990, "A new attenuation relation for peak horizontal acceleration of strong earthquake ground motion in Japan", Bulletin of the Seismological Society of America 80: 757-783.
Grant-Taylor, T.L., Adams, R.D., Hatherton, T., Milne, J.D.G., Northey, R.D., Stephenson, W.R. 1974, "Microzoning for earthquake effects in Wellington", DSIR Bulletin 213.
Hayes, R.C. 1943, "Earthquakes in New Zealand during the year 1942", New Zealand Journal of Science and Technology 24: 191-194.
Hays, W.W. 1980, "Procedures for estimating earthquake ground motions", U.S. Geological Survey Professional Paper 1114. DOI: https://doi.org/10.3133/pp1114
Idriss, I.M. 1990, "Response of soft soils during earthquakes", In Proceedings, Memorial Symposium to Honour Professor H.B. Seed. University of California at Berkeley: 273-289.
Idriss, I.M. 1985, "Evaluating seismic risk in engineering practice", In Proceedings, Eleventh International Conference on Soil Mechanics and Foundation Engineering. San Francisco: 255-360.
Joyner, W.B., Boore, D.M. 1981, "Peak horizontal acceleration and velocity from strong-motion records including records from the 1979 Imperial Valley, California, earthquake", Bulletin of the Seismological Society of America 71: 2011-2038. DOI: https://doi.org/10.3133/ofr81365
Krinitzsky, E.L., Chang, F.K. 1988, "Intensity-related earthquake ground motions", Bulletin of the Association of Engineering Geologists 25: 425-435. DOI: https://doi.org/10.2113/gseegeosci.xxv.4.425
Lowry, M.A., Ede, S.C., Harris, J.S. 1989, "Assessment of seismic intensities resulting from the 1987 Edgecumbe earthquake, New Zealand, and implications for modernising the intensity scale", New Zealand Journal of Geology and Geophysics 32: 145-153. DOI: https://doi.org/10.1080/00288306.1989.10421398
New Zealand Seismological Observatory. 1992, Personal communication, Institute of Geological & Nuclear Sciences.
Plafker, G., Galloway, J. 1989, "Lessons learned from the Loma Prieta, California, earthquake of October 17, 1989", U.S. Geological Survey Circular 1045. DOI: https://doi.org/10.3133/cir1045
Rynn, J. M. W., Brennan, E., Hughes, P .R., Pedersen, LS., Stuart, H.J. 1992, "The Newcastle, Australia, earthquake: the facts and the misconceptions", Bulletin of the New Zealand National Society for Earthquake Engineering 25 2; 77-144.
Seed, H.B., Romo, M.P., Sun, I.I., Jaime, A., Lysmer, J. 1988, "Relationship between soil conditions and 35. earthquake ground motions", Earthquake Spectra 4: 687-730.
Smith, W.D. 1992, Personal communication, Institute of Geo-logical & Nuclear Sciences.
Smith, W.D. 1981, "The vast event - how vast how often? a statistical perspective of earthquake occurrence", In Large Earthquakes in New Zealand. The Royal Society of New Zealand Miscellaneous Series No. 5: 17-23.
Smith, W. D. , Berryman, K.R. 1986, "Earthquake hazard in New Zealand: inferences from seismology and geology", Royal Society of New Zealand Bulletin 24: 223-243.
Sritharan, S., McVerry, G.H. 1992, "Microzone effects in the Hutt Valley in records from a strong-motion accelerograph array", Bulletin of the New Zealand National Society for Earthquake Engineering (this volume). DOI: https://doi.org/10.5459/bnzsee.25.4.246-264
Stephenson, W .R. 1991, "An assessment of the proportion of earthquakes likely to be amplified by flexible sediments", In Proceedings, Pacific Conference on Earthquake Engineering. Auckland, New Zealand: v. 3. p. 149-158.
Stephenson, W.R., Barker, P.R. 1992, "Evaluation of sediment properties in the Lower Hutt and Porirua areas by means of cone and seismic cone penetration tests", Bulletin of the New Zealand National Society for Earthquake Engineering (this volume). DOI: https://doi.org/10.5459/bnzsee.25.4.265-285
Taber, J.J., Smith E.G.C. 1992, "Frequency dependent amplification of weak ground motions in Porirua and Lower Hutt, New Zealand", Bulletin of the New Zealand National Society for Earthquake Engineering (this volume). DOI: https://doi.org/10.5459/bnzsee.25.4.303-331
Tucker, B.E., King, J.L., Hatzfeld, D., Nersesov, LL. 1984, "Observations of hard-rock site effects", Bulletin of the Seismological Society of America 74: 121-136.
U.S. Geological Survey Staff 1990, "The Loma Prieta, California, earthquake: an anticipated event", Science 247: 286-293. DOI: https://doi.org/10.1126/science.247.4940.286
Van Dissen, R.J., Berryman, K.R., Pettinga, J.R., Hill, N.L. 1992, "Paleoseismicity of the Wellington-Hutt Valley segment of the Wellington fault, North Island, New Zealand", New Zealand Journal of Geology and Geophysics 35: 165-176. DOI: https://doi.org/10.1080/00288306.1992.9514511
Van Dissen, R.J., Berryman, K.R. 1991, "Timing, size, and recurrence interval of prehistoric earthquakes in the Wellington region, New Zealand", In Proceedings, Pacific Conference on Earthquake Engineering. Auckland, New Zealand; Vol. 3, p. 239- 249.
Wood, H.O. 1908, "Distribution of apparent intensity of San Francisco in the California earthquake of April 18, 1906", Report of the State Earthquake Investigation Commission, Washington, D.C., Carnegie Institute Publication 87: 220-245.
Copyright (c) 1992 R. J. Van Dissen, J. J. Taber, W. R. Stephenson, S. Sritheran, S. A. L. Read, G. H. McVerry, G. D. Dellow, P. R. Barker
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