Distribution of geological materials in Lower Hutt and Porirua, New Zealand

A component of a ground shaking hazard assessment

  • G. D. Dellow GNS Science, Lower Hutt, New Zealand
  • S. A. L. Read GNS Science, Lower Hutt, New Zealand
  • J. G. Begg GNS Science, Lower Hutt, New Zealand
  • R. J. Van Dissen GNS Science, Lower Hutt, New Zealand
  • N. D. Perrin GNS Science, Lower Hutt, New Zealand

Abstract

Geological materials in the Lower Hutt, Eastbourne, Wainuiomata, and Porirua urban areas are mapped and described as part of a multi-disciplinary assessment of seismic ground shaking hazards. Emphasis is mainly on the flat-lying parts of these areas which are underlain by variable Quaternary-age sediments that overlie Permian-Mesozoic age 'greywacke' bedrock. Within the Quaternary-age sediments, the two material types recognised on strength characteristics are:

1)  Soft sediments, typically composed of normally consolidated, fine-grained materials (sand, silt and clay), with typical standard penetration values (SPT) of <20 blows/300 mm; and 


2)  Loose to compact coarser-grained materials (sand, gravel), with SPT values of >20 blows/300 mm. 


The total thickness and nature of Quaternary-age sediments in the study areas is described, with particular emphasis on the thickness and geotechnical properties of near-surface sediments. Such sediments are considered likely to have a significant influence on the an1plification and attenuation of ground shaking intensity during earthquakes.

In the Lower Hutt valley, near-surface soft sediments greater than 10 m thick have an areal extent of -16 km2. Such soft sediments underlie much of Petone and the Lower Hutt urban and city centres, and have a maximum known thickness of 27 m near the western end of the Petone foreshore. In the Wainuiomata area, near-surface soft sediments greater than 10 m thick have an areal extent of - 3 km2, and attain a maximum thickness of 32 m. In Porirua, near-surface soft sediments have a maximum thickness of 14 m, cover an area of -2km2, and underlie much of the city centre. In the Lower Hutt valley the total known thickness of Quaternary-age sediments, including near-surface soft sediments is 300 m. Quaternary-age sediments are very much thinner in other areas, with thicknesses of 60 m recorded in Wainuiomata, 10 m in Eastbourne, and 90 m in the Porirua area.

References

Adkin, G.L. 1921, "Porirua Harbour: a study of its shore-line and other physiographic features", Transactions of the New Zealand Institute 53: 144-156.

Begg, J.G., Brown, L.J. 1991, "Stratigraphic drillhole completion report, Wainuiomata, Wellington, New Zealand", Unpublished DSIR Geology and Geophysics Report G156.

Borcherdt, R.D. 1970, "Effects of local geology on ground motion near San Francisco Bay", Bulletin of the Seismological Society of America 60: 29-61

Brown, Ian R. Assoc 1991, "Seismic hazard assessment of Lower Hutt city", Unpublished Ian R. Brown Associates contract report 197.

Cowan, M., Hatherton, T. 1968, "Gravity surveys in Wellington and Hutt Valley". New Zealand Journal of Geology and Geophysics 11(1): 1-15. DOI: https://doi.org/10.1080/00288306.1968.10423670

Donaldson, LG., Campbell, D.G. 1977, "Groundwater of the Hutt Valley - Port Nicholson alluvial valley - A resource evaluation", DSIR information series 124.

Fry, B.M. 1985, "A late Quaternary history of the Lower Hutt Valley: A tool for town planning", Unpublished BSc (hons) project, Geology Department, University of Victoria.

Grant-Taylor, T.L. 1959, "Geology of the Hutt Valley", Proceedings of the New Zealand Ecological Society 6: 31-35.

Healy, W.B. (Editor) 1980, "Pauatahanui Inlet - an environmental study", New Zealand DSIR information series 141. 198 pp.

Henderson, J. 1929, "Wainui-o-mata and Orongorongo valleys", New Zealand Geological Survey 23rd annual report (ns): 12-13.

Hicks, S.R. 1974, "Shallow seismic surveys at Wainuiomata, Waikanae and Whangaimoana", Unpublished DSIR Geophysics Division Report 93.

Hicks, S.R. 1982, "Wainuiomata water reserve seismic refraction surveys of damsites 2, 3 and 4", Unpublished DSIR Geophysics Division Report 145.

Katayama, T. 1982, "An engineering prediction model of acceleration response spectra and its application to seismic hazard mapping", Earthquake Engineering and Structural Dynamics 10: 149-163. DOI: https://doi.org/10.1002/eqe.4290100111

Kingma, J.T. 1967, "Sheet 12 Wellington. Geological map of New Zealand 1:250 000", Department of Scientific and Industrial Research, Wellington.

Krinitzsky, E.L., Chang, F.K. 1988, "Intensity-related earthquake ground motions", Bulletin of the Association of Engineering Geologists 25(4): 425-435. DOI: https://doi.org/10.2113/gseegeosci.xxv.4.425

Seed, H.B., Idriss, I.M. 1982, "Ground motions and soil liquefaction during earthquakes", Earthquake Engineering Research Institute Monograph.

Sritharan, S., McVerry, G.H. 1992, "Microzoning 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., Barker, P.R. 1992, "Evaluation of sediment properties in 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

Stevens, G.R. 1956, "Stratigraphy of the Hutt Valley, New Zealand," New Zealand Journal of Science and Technology B38: 201-235.

Suggate, R.P., Stevens, G.R., Te Punga, M.T. (Editors) 1978, "The geology of New Zealand", New Zealand Government Printer, Wellington. Two volumes. 820p.

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

Tinsley, F.C., Fumal, T.E. 1985; "Mapping Quaternary sedimentary deposits for areal variations in shaking response," p101-125 in Ziony, J.I. (ed) Evaluating Earthquake Hazards in the Los Angeles Region - An Earth Science Perspective. United States Geological Survey Professional Paper 1360.

Van Dissen, R.J., Taber, J.J., Stephenson, W.R., Sritharan, S., Read, S.A.L., McVerry, G.H., Dellow, G.D., Barker, P.R. 1992, "Earthquake ground shaking hazard assessment for the Lower Hutt and Porirua areas, New Zealand", Bulletin of the New Zealand National Society for Earthquake Engineering (this volume). DOI: https://doi.org/10.5459/bnzsee.25.4.286-302

Webby, B.D. 1959, "The structure of the Lower Mesozoic rocks in the Porirua District," New Zealand Journal of Geology and Geophysics 2(3): 528-40. DOI: https://doi.org/10.1080/00288306.1959.10423158

Published
1992-12-31
How to Cite
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. Bulletin of the New Zealand Society for Earthquake Engineering, 25(4), 332-344. https://doi.org/10.5459/bnzsee.25.4.332-344
Section
Articles