Landslides caused by the Mw7.8 Kaikōura earthquake and the immediate response

  • Sally Dellow GNS Science, Lower Hutt, New Zealand https://orcid.org/0000-0003-2033-0966
  • Chris Massey GNS Science, Lower Hutt, New Zealand
  • Simon Cox GNS Science, Lower Hutt, New Zealand
  • Garth Archibald GNS Science, Lower Hutt, New Zealand
  • John Begg GNS Science, Lower Hutt, New Zealand https://orcid.org/0000-0001-6935-6855
  • Zane Bruce GNS Science, Lower Hutt, New Zealand
  • Jon Carey GNS Science, Lower Hutt, New Zealand
  • Jonathan Davidson GNS Science, Lower Hutt, New Zealand
  • Fernando Della Pasqua GNS Science, Lower Hutt, New Zealand
  • Phil Glassey GNS Science, Lower Hutt, New Zealand https://orcid.org/0000-0002-1204-2393
  • Matt Hill GNS Science, Lower Hutt, New Zealand
  • Katie Jones GNS Science, Lower Hutt, New Zealand
  • Barbara Lyndsell GNS Science, Lower Hutt, New Zealand https://orcid.org/0000-0002-9084-6506
  • Biljana Lukovic GNS Science, Lower Hutt, New Zealand
  • Sam McColl Massey University, Palmerston North, New Zealand
  • Mark Rattenbury GNS Science, Lower Hutt, New Zealand https://orcid.org/0000-0003-3270-2675
  • Stuart Read GNS Science, Lower Hutt, New Zealand
  • Brenda Rosser GNS Science, Lower Hutt, New Zealand
  • Corinne Singeisen ETH Zurich, Zurich, Switzerland
  • Dougal Townsend GNS Science, Lower Hutt, New Zealand
  • Pilar Villamor GNS Science, Lower Hutt, New Zealand
  • Marlene Villeneuve University of Canterbury, Christchurch, New Zealand
  • Jonathan Godt USGS Landslide Team, Reston, VA, USA https://orcid.org/0000-0002-8737-2493
  • Randall Jibson USGS Landslide Team, Reston, Virginia, United States https://orcid.org/0000-0003-3399-0875
  • Kate Allstadt USGS Landslide Team, Reston, Virginia, United States https://orcid.org/0000-0003-4977-5248
  • Francis Rengers USGS Landslide Team, Reston, Virginia, United States https://orcid.org/0000-0002-1825-0943
  • Joseph Wartman University of Washington, Seattle, USA
  • Ellen Rathje University of Texas, Austin, USA https://orcid.org/0000-0002-4169-7153
  • Nick Sitar University of California Berkeley, Berkeley, USA
  • Athanasopoulos-Zekkos Adda University of Michigan, Ann Arbor, USA
  • John Manousakis Elixis Group Ltd., Greece
  • Michael Little University of Texas, Austin, USA

Abstract

Tens of thousands of landslides were generated over 10,000 km2 of North Canterbury and Marlborough as a consequence of the 14 November 2016, Mw7.8 Kaikōura Earthquake. The most intense landslide damage was concentrated in 3500 km2 around the areas of fault rupture. Given the sparsely populated area affected by landslides, only a few homes were impacted and there were no recorded deaths due to landslides. Landslides caused major disruption with all road and rail links with Kaikōura being severed. The landslides affecting State Highway 1 (the main road link in the South Island of New Zealand) and the South Island main trunk railway extended from Ward in Marlborough all the way to the south of Oaro in North Canterbury.

The majority of landslides occurred in two geological and geotechnically distinct materials reflective of the dominant rock types in the affected area. In the Neogene sedimentary rocks (sandstones, limestones and siltstones) of the Hurunui District, North Canterbury and around Cape Campbell in Marlborough, first-time and reactivated rock-slides and rock-block slides were the dominant landslide type. These rocks also tend to have rock material strength values in the range of 5-20 MPa. In the Torlesse ‘basement’ rocks (greywacke sandstones and argillite) of the Kaikōura Ranges, first-time rock and debris avalanches were the dominant landslide type. These rocks tend to have material strength values in the range of 20-50 MPa.

A feature of this earthquake is the large number (more than 200) of valley blocking landslides it generated. This was partly due to the steep and confined slopes in the area and the widely distributed strong ground shaking. The largest landslide dam has an approximate volume of 12(±2) M m3 and the debris from this travelled about 2.7 km2 downslope where it formed a dam blocking the Hapuku River. The long-term stability of cracked slopes and landslide dams from future strong earthquakes and large rainstorms are an ongoing concern to central and local government agencies responsible for rebuilding homes and infrastructure. A particular concern is the potential for debris floods to affect downstream assets and infrastructure should some of the landslide dams breach catastrophically.

At least twenty-one faults ruptured to the ground surface or sea floor, with these surface ruptures extending from the Emu Plain in North Canterbury to offshore of Cape Campbell in Marlborough. The mapped landslide distribution reflects the complexity of the earthquake rupture. Landslides are distributed across a broad area of intense ground shaking reflective of the elongate area affected by fault rupture, and are not clustered around the earthquake epicentre. The largest landslides triggered by the earthquake are located either on or adjacent to faults that ruptured to the ground surface. Surface faults may provide a plane of weakness or hydrological discontinuity and adversely oriented surface faults may be indicative of the location of future large landslides. Their location appears to have a strong structural geological control. Initial results from our landslide investigations suggest predictive models relying only on ground-shaking estimates underestimate the number and size of the largest landslides that occurred.

References

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Stirling MW, Litchfield NJ, Villamor P, Van Dissen RJ, Nicol A, Pettinga J, Barnes P, Langridge RM, Little T, Barrell DJA, Mountjoy J, Ries WF, Rowland J, Fenton C, Hamling I, Asher C, Barrier A, Benson A, Bischoff A, Borella , Carne R, Cochran UA, Cockroft M, Cox SC, Duke G, Fenton F, Gasston C, GrimshawC, Hale D, Hall B, Hao KX, Hatem A, Hemphill-Haley M, Heron DW, Howarth J, Juniper Z, Kane T, Kearse J, Khajavi N, Lamarche G, Lawson S, Lukovic B, Madugo C, Manousakis I, McColl S, Noble D, Pedley K, Sauer K, Stahl T, Strong DT, Townsend DB, Toy V, Villeneuve M, Wandres A, Williams J, Woelz S, and R. Zinke (2017). “The Mw7.8 2016 Kaikōura earthquake: Surface fault rupture and seismic hazard context”. Bulletin of the New Zealand Society for Earthquake Engineering, 50(2): 73-84. DOI: https://doi.org/10.5459/bnzsee.50.2.73-84

Published
2017-06-30
How to Cite
Dellow, S., Massey, C., Cox, S., Archibald, G., Begg, J., Bruce, Z., Carey, J., Davidson, J., Pasqua, F. D., Glassey, P., Hill, M., Jones, K., Lyndsell, B., Lukovic, B., McColl, S., Rattenbury, M., Read, S., Rosser, B., Singeisen, C., Townsend, D., Villamor, P., Villeneuve, M., Godt, J., Jibson, R., Allstadt, K., Rengers, F., Wartman, J., Rathje, E., Sitar, N., Adda, A.-Z., Manousakis, J., & Little, M. (2017). Landslides caused by the Mw7.8 Kaikōura earthquake and the immediate response. Bulletin of the New Zealand Society for Earthquake Engineering, 50(2), 106-116. https://doi.org/10.5459/bnzsee.50.2.106-116
Section
Articles

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