TY - JOUR

T1 - Landslides caused by the Mw7.8 Kaikōura earthquake and the immediate response

AU - Dellow, Sally

AU - Massey, Chris

AU - Cox, Simon

AU - Archibald, Garth

AU - Begg, John

AU - Bruce, Zane

AU - Carey, Jon

AU - Davidson, Jonathan

AU - Della Pasqua, Fernando

AU - Glassey, Phil

AU - Hill, Matt

AU - Jones, Katie

AU - Lyndsell, Barbara

AU - Lukovic, Biljana

AU - McColl, Sam

AU - Rattenbury, Mark

AU - Read, Stuart

AU - Rosser, Brenda

AU - Singeisen, Corinne

AU - Townsend, Dougal

AU - Villamor, Pilar

AU - Villeneuve, Marlene

AU - Godt, Jonathan

AU - Jibson, Randall

AU - Allstadt, Kate

AU - Rengers, Francis

AU - Wartman, Joseph

AU - Rathje, Ellen

AU - Sitar, Nick

AU - Adda, Athanasopoulos Zekkos

AU - Manousakis, John

AU - Little, Michael

PY - 2017/6/1

Y1 - 2017/6/1

N2 - Tens of thousands of landslides were generated over 10,000 km2of North Canterbury and Marlborough as aconsequence of the 14 November 2016, MW7.8 Kaikōura Earthquake. The most intense landslide damagewas concentrated in 3500 km2around the areas of fault rupture. Given the sparsely populated area affectedby 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 landslidesaffecting State Highway 1 (the main road link in the South Island of New Zealand) and the South Islandmain trunk railway extended from Ward in Marlborough all the way to the south of Oaro in NorthCanterbury.The majority of landslides occurred in two geological and geotechnically distinct materials reflective of thedominant rock types in the affected area. In the Neogene sedimentary rocks (sandstones, limestones andsiltstones) of the Hurunui District, North Canterbury and around Cape Campbell in Marlborough, first-timeand reactivated rock-slides and rock-block slides were the dominant landslide type. These rocks also tend tohave rock material strength values in the range of 5-20 MPa. In the Torlesse ‘basement’ rocks (greywackesandstones and argillite) of the Kaikōura Ranges, first-time rock and debris avalanches were the dominantlandslide 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 groundshaking. The largest landslide dam has an approximate volume of 12(±2) M m3and the debris from thistravelled about 2.7 km2downslope where it formed a dam blocking the Hapuku River. The long-termstability of cracked slopes and landslide dams from future strong earthquakes and large rainstorms are anongoing concern to central and local government agencies responsible for rebuilding homes andinfrastructure. A particular concern is the potential for debris floods to affect downstream assets andinfrastructure 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 extendingfrom the Emu Plain in North Canterbury to offshore of Cape Campbell in Marlborough. The mappedlandslide distribution reflects the complexity of the earthquake rupture. Landslides are distributed across abroad area of intense ground shaking reflective of the elongate area affected by fault rupture, and are notclustered around the earthquake epicentre. The largest landslides triggered by the earthquake are locatedeither on or adjacent to faults that ruptured to the ground surface. Surface faults may provide a plane ofweakness or hydrological discontinuity and adversely oriented surface faults may be indicative of thelocation 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-shakingestimates underestimate the number and size of the largest landslides that occurred.

AB - Tens of thousands of landslides were generated over 10,000 km2of North Canterbury and Marlborough as aconsequence of the 14 November 2016, MW7.8 Kaikōura Earthquake. The most intense landslide damagewas concentrated in 3500 km2around the areas of fault rupture. Given the sparsely populated area affectedby 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 landslidesaffecting State Highway 1 (the main road link in the South Island of New Zealand) and the South Islandmain trunk railway extended from Ward in Marlborough all the way to the south of Oaro in NorthCanterbury.The majority of landslides occurred in two geological and geotechnically distinct materials reflective of thedominant rock types in the affected area. In the Neogene sedimentary rocks (sandstones, limestones andsiltstones) of the Hurunui District, North Canterbury and around Cape Campbell in Marlborough, first-timeand reactivated rock-slides and rock-block slides were the dominant landslide type. These rocks also tend tohave rock material strength values in the range of 5-20 MPa. In the Torlesse ‘basement’ rocks (greywackesandstones and argillite) of the Kaikōura Ranges, first-time rock and debris avalanches were the dominantlandslide 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 groundshaking. The largest landslide dam has an approximate volume of 12(±2) M m3and the debris from thistravelled about 2.7 km2downslope where it formed a dam blocking the Hapuku River. The long-termstability of cracked slopes and landslide dams from future strong earthquakes and large rainstorms are anongoing concern to central and local government agencies responsible for rebuilding homes andinfrastructure. A particular concern is the potential for debris floods to affect downstream assets andinfrastructure 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 extendingfrom the Emu Plain in North Canterbury to offshore of Cape Campbell in Marlborough. The mappedlandslide distribution reflects the complexity of the earthquake rupture. Landslides are distributed across abroad area of intense ground shaking reflective of the elongate area affected by fault rupture, and are notclustered around the earthquake epicentre. The largest landslides triggered by the earthquake are locatedeither on or adjacent to faults that ruptured to the ground surface. Surface faults may provide a plane ofweakness or hydrological discontinuity and adversely oriented surface faults may be indicative of thelocation 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-shakingestimates underestimate the number and size of the largest landslides that occurred.

UR - http://www.scopus.com/inward/record.url?scp=85021837866&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:85021837866

VL - 50.2017

SP - 106

EP - 116

JO - Bulletin of the New Zealand Society for Earthquake Engineering

JF - Bulletin of the New Zealand Society for Earthquake Engineering

SN - 1174-9857

IS - 2

ER -