Estimating co-seismic subsidence in the Hutt Valley resulting from rupture of the Wellington Fault, New Zealand
Ground deformation can contribute significantly to losses in major earthquakes. Areas that suffer permanent ground deformation in addition to strong ground shaking typically sustain greater levels of damage and loss than areas suffering strong ground-shaking alone. The lower Hutt Valley of the Wellington region, New Zealand, is adjacent to the active Wellington Fault. The long-term signal of vertical deformation there is subsidence, and the most likely driver of this is rupture of the Wellington Fault.
In 1855 the Mw ~8.2 Wairarapa Earthquake resulted in uplift of the lower Hutt Valley area and created an expectation that future earthquakes would do the same. However, sediments beneath the lower Hutt Valley floor up to c. 220 thousand years old provide data that when combined with the international sea level curve demonstrate cumulative net subsidence of up to c. 155 m during that period. Recent refinement of rupture parameters for the Wellington Fault (and other faults in the region), based on new field data, has spurred us to reassess estimates of vertical deformation in the Hutt Valley that would result from rupture of the Wellington Fault. Using a logic tree framework, we calculate subsidence for an “average” Wellington Fault event of ~1.9 m near Petone, ~1.7m near Lower Hutt City, ~1.4 m near Seaview, and ~0 m in the Taita area. Such a distribution of vertical deformation would result in large areas of Alicetown-Petone and Moera-Seaview subsiding below sea level. We also calculate and present “minimum” and “maximum” credible subsidence values, which are approximately half and twice the mean values, respectively. This ground deformation hazard certainly has societal implications, and we are working with local and regional councils to develop a range of mitigation strategies.
GNS Science (2015). GNS Science Active Faults Database. http://data.gns.cri.nz/af/. (Accessed 6/8/2015).
Langridge RM, Ries WF, Litchfield NJ, Villamor P, Van Dissen RJ, Rattenbury MS, Barrell DJA, Heron DW, Haubrock S, Townsend DB, Cox S, Berryman KR, Nicol A, Lee JA, and Stirling M (2016). “The New Zealand Active Faults Database”. New Zealand Journal of Geology and Geophysics, 59(1): 86–96. doi:10.1080/00288306.2015.1112818. DOI: https://doi.org/10.1080/00288306.2015.1112818
Begg JG and Mazengarb C (1996). “Geology of the Wellington area, sheets R27, R28, and part Q27, scale 1:50,000”. Geological Map 22, Institute of Geological & Nuclear Sciences Ltd., Lower Hutt, 128 pp + map.
Grapes RH and Downes G (1997). “The 1855 Wairarapa, New Zealand, Earthquake: Analysis of Historical Data”. Bulletin of the New Zealand National Society for Earthquake Engineering, 30(4): 271-368 DOI: https://doi.org/10.5459/bnzsee.30.4.271-368
Begg JG, Van Dissen RJ, Rhoades DA, Lukovic B, Heron DW, Darby DJ and Brown LJ (2002). “Coseismic Subsidence in the Lower Hutt Valley Resulting from Rupture of the Wellington Fault”. Client Report 2002/140, Institute of Geological & Nuclear Sciences Ltd., Lower Hutt, 70pp.
Begg JG, Van Dissen RJ and Rhoades DA (2004). “Subsidence in the Lower Hutt Valley and the Interplay between Wellington and Wairarapa Fault Earthquakes”. Proceedings of the New Zealand Society for Earthquake Engineering Technical Conference, Rotorua, New Zealand, 19-21 March 2004, Paper No 43, 9 pp.
Wood RA and Davy BW (1992). “Interpretation of Geophysical Data Collected in Wellington Harbour”. Client Report 1992/78, Institute of Geological & Nuclear Sciences Ltd., Lower Hutt, 18 pp + figures.
Canterbury Earthquakes Royal Commission (2012). “Volume 7: Roles and Responsibilities, Section 5: Canterbury Regional Council and Christchurch City Council – Management of Earthquake Risk”. Canterbury Earthquakes Royal Commission, Christchurch, 95-105.
Hughes MW, Quigley MC, van Ballegooy S, Deam BL, Bradley BA, Hart DE and Measures R (2015). “The Sinking City: Earthquakes Increase Flood Hazard in Christchurch, New Zealand”. GSA Today, 25(3–4): 4-10. doi: 10.1130/GSATG221A.1. DOI: https://doi.org/10.1130/GSATG221A.1
Quigley MC, Hughes MW, Bradley BA, van Ballegooy S, Reid C, Morgenroth J, Horton T, Duffy B, and Pettinga JR (2016). “The 2010-2011 Canterbury Earthquake Sequence: Environmental effects, Seismic Triggering Thresholds and Geological Legacy”. Tectonophysics, 672-673: 228-274.
Mildenhall, DC (1995). “Pleistocene palynology of the Petone and Seaview drillholes, Petone, Lower Hutt Valley, North Island, New Zealand”. Journal of the Royal Society of New Zealand, 25(2): 207-262. DOI: https://doi.org/10.1080/03014223.1995.9517488
Rabineau, M, Berné, S, Olivet, J-L, Aslanian, D, Guillocheau, F, and Joseph, P (2006). “Paleo sea levels reconsidered from direct observation of paleoshoreline position during Glacial Maxima (for the last 500,000 yr)”. Earth and Planetary Science Letters, 252: 119-137.
Little TA, Van Dissen R, Schermer E and Carne R (2009). “Late Holocene Surface Ruptures on the Southern Wairarapa Fault, New Zealand: Link Between Earthquakes and the Raising of Beach Ridges on a Rocky Coast”. Lithosphere, 1(1): 4-28. doi: 10.1130/L7.1. DOI: https://doi.org/10.1130/L7.1
Van Dissen R, Barnes P, Beavan J, Cousins J, Dellow G, Francois-Holden C, Fry B, Langridge R, Litchfield N, Little T, McVerry G, Ninis D, Rhoades D, Robinson R, Saunders W, Villamor P, Wilson K, Barker P, Berryman K, Benites R, Brackley H, Bradley B, Carne R, Cochran U, Hemphill-Haley M, King A, Lamarche G, Palmer N, Perrin N, Pondard N, Rattenbury M, Read S, Semmens S, Smith E, Stephenson W, Wallace L, Webb T and Zhao J (2010). “It’s Our Fault: Better Defining Earthquake Risk in Wellington”. Proceedings of the 11th IAEG (International Association for Engineering Geology and the Environment) Congress, Auckland, New Zealand, 5– 10 September, 2010, 737–746.
Rhoades DA, Van Dissen RJ, Langridge RM, Little TA, Ninis D, Smith EGC and Robinson R (2011). “Re-evaluation of Conditional Probability of Rupture of the Wellington-Hutt Valley Segment of the Wellington Fault”. Bulletin of the New Zealand Society for Earthquake Engineering, 44(2): 77–86. DOI: https://doi.org/10.5459/bnzsee.44.2.77-86
Van Dissen RJ, Rhoades DA, Little T, Litchfield NJ, Carne R and Villamor P (2013). “Conditional Probability of Rupture of the Wairarapa and Ohariu Faults, New Zealand”. New Zealand Journal of Geology and Geophysics, 56(2): 53–67. doi: 10.1080/00288306.2012.756042. DOI: https://doi.org/10.1080/00288306.2012.756042
Townsend DB, Begg JG, Van Dissen RJ, Rhoades DA, Saunders WSA and Little TA (2015). “Estimating Co-Seismic Subsidence in the Hutt Valley associated with Rupture of the Wellington Fault”. Science Report 2015/02, GNS Science, Lower Hutt, 73 pp. http://shop.gns.cri.nz/GNSShop/Itemlist/ItemDetail.aspx?id=SR15_02-PDF
Kulkarni RB, Youngs RR and Coppersmith KJ (1984). “Assessment of Confidence Intervals for Results of Seismic Hazard Analysis”. Proceedings of the Eighth World Conference on Earthquake Engineering, San Francisco, USA, 21-28 July 1984, Vol. 1, 263–270.
McSaveney MJ, Graham IJ, Begg JG, Beu AG, Hull AG, Kim K and Zondervan A (2006). “Late Holocene Uplift of Beach Ridges at Turakirae Head, South Wellington Coast, New Zealand”. New Zealand Journal of Geology and Geophysics, 49(3): 337–358. DOI: https://doi.org/10.1080/00288306.2006.9515172
Savage JC (1983). “A Dislocation Model of Strain Accumulation and Release at a Subduction Zone”. Journal of Geophysical Research, 88: 4984-4996.
Hyndman RD and Wang K (1993). “Tectonic Constraints on the Zone of Major Thrust Earthquake Failure: The Cascadia Subduction Zone”. Journal of Geophysical Research, 98: 2039-2060.
Sugiyam Y (1994). “Neotectonics of Southwest Japan Due to the Right-Oblique Subduction of the Philippine Sea Plate”. Geofisica International, 33: 53-76.
Gibb JG (1986). “A New Zealand Regional Holocene Eustatic Sea-Level Curve and Its Application to Determination of Vertical Tectonic Movements: a contribution to IGCP-Project 200”. Proceedings of the International Symposium on Recent Crustal Movements of the Pacific Region, Wellington, New Zealand, 9-14 February 1984, Royal Society of New Zealand Bulletin 24, 377–395.
Hayward BW, Grenfell HR, Sabaa AT, and Clark KJ (2012). “Foraminiferal Evidence for Holocene Synclinal Folding at Porangahau, Southern Hawkes Bay, New Zealand”. New Zealand Journal of Geology and Geophysics, 55(1): 21–35. doi: 10.1080/00288306.2011.615845. DOI: https://doi.org/10.1080/00288306.2011.615845
Hecker S, Abrahamson NA, and Wooddell KE (2013). “Variability of Displacement at a Point: Implications for Earthquake-Size Distribution and Rupture Hazard on Faults”. Bulletin of the Seismological Society of America, 103(2A): 651–674.
Langridge RM, Van Dissen RJ, Villamor P and Little TA (2009). “It's Our Fault: Wellington Fault Paleo-earthquake Investigations: Final Report”. Consultancy Report 2008/344, GNS Science, Lower Hutt, 45 pp.
Langridge RM, Van Dissen RJ, Rhoades DA, Villamor P, Little T, Litchfield NJ, Clark KJ and Clark D (2011). “Five Thousand Years of Surface Ruptures on the Wellington Fault, New Zealand: Implications for Recurrence and Fault Segmentation”. Bulletin of the Seismological Society of America, 101(5): 2088–2107. doi: 10.1785/0120100340. DOI: https://doi.org/10.1785/0120100340
Little TA, Van Dissen RJ, Rieser U, Smith EGC and Langridge RM (2010). “Coseismic Strike Slip at a Point During the Last Four Earthquakes on the Wellington Fault Near Wellington, New Zealand”. Journal of Geophysical Research. Solid Earth, 115(5): B05403. doi:10.1029/2009JB006589. DOI: https://doi.org/10.1029/2009JB006589
Ninis D, Little TA, Van Dissen RJ, Litchfield NJ, Smith EGC, Wang N, Rieser U and Henderson CM (2013). “Slip rate on the Wellington Fault, New Zealand, During the Late Quaternary: Evidence for Variable Slip During the Holocene”. Bulletin of the Seismological Society of America, 103(1): 559–57. doi: 10.1785/0120120162.