Investigating the Basal Shear Zone of the Submarine Tuaheni Landslide Complex, New Zealand: A Core-Log-Seismic Integration Study

G. J. Crutchley; J. Elger; J. Kuhlmann; J. J. Mountjoy; A. Orpin; A. Georgiopoulou; M.j. Carey; B. Dugan; S. Cardona; S. Han; A. Cook; E. J. Screaton; I. A. Pecher; P. Barnes; K. Huhn

doi:10.1029/2021JB021997

Investigating the Basal Shear Zone of the Submarine Tuaheni Landslide Complex, New Zealand: A Core-Log-Seismic Integration Study

G. J. Crutchley^*, J. Elger, J. Kuhlmann, J. J. Mountjoy, A. Orpin, A. Georgiopoulou, M.j. Carey, B. Dugan, S. Cardona, S. Han, A. Cook, E. J. Screaton, I. A. Pecher, P. Barnes, K. Huhn

^*Corresponding author for this work

Geography, Earth and Environmental Sciences

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Abstract

Although submarine landslides have been studied for decades, a persistent challenge is the integration of diverse geoscientific datasets to characterize failure processes. We present a core-log-seismic integration study of the Tuaheni Landslide Complex to investigate intact sediments beneath the undeformed seafloor as well as post-failure landslide deposits. Beneath the undeformed seafloor are coherent reflections underlain by a weakly-reflective and chaotic seismic unit. This chaotic unit is characterized by variable shear strength that correlates with density fluctuations. The basal shear zone of the Tuaheni landslide likely exploited one (or more) of the low shear strength intervals. Within the landslide deposits is a widespread “Intra-debris Reflector”, previously interpreted as the landslide's basal shear zone. This reflector is a subtle impedance drop around the boundary between upper and lower landslide units. However, there is no pronounced shear strength change across this horizon. Rather, there is a pronounced reduction in shear strength ∼10–15 m above the Intra-debris Reflector that presumably represents an induced weak layer that developed during failure. Free gas accumulates beneath some regions of the landslide and is widespread deeper in the sedimentary sequence, suggesting that free gas may have played a role in pre-conditioning the slope to failure. Additional pre-conditioning or failure triggers could have been seismic shaking and associated transient fluid pressure. Our study underscores the importance of detailed core-log-seismic integration approaches for investigating basal shear zone development in submarine landslides.

Original language	English
Article number	e2021JB021997
Number of pages	24
Journal	Journal of Geophysical Research: Solid Earth
Volume	127
Issue number	1
Early online date	27 Dec 2021
DOIs	https://doi.org/10.1029/2021JB021997
Publication status	Published - Jan 2022

Bibliographical note

Funding Information:
We are grateful for excellent support from captains and crew of research voyages TAN1404 (), SO247 (), and IODP Expedition 372 (). This paper used data and images provided by IODP Expedition 372. We thank the science party and technical staff that assisted with sample and data acquisition. We also thank Tim Freudenthal (MARUM) and the MeBo200 team for their excellent support during drilling (SO247), and Tim for further post‐cruise advice about drilling parameters. We thank Felix Gross, Sebastian Krastel and Christoph Böttner for valuable discussions about the Tuaheni landslide in recent years. We are grateful to Stefan Bünz and two anonymous reviewers for their insightful reviews that improved the quality of this paper, and to the Editor Yves Bernabe for handling this submission. Seismic data acquisition and processing was jointly funded by the New Zealand Ministry for Business Innovation and Employment (MBIE), NIWA and GNS Science Core funding and the Deutsche Forschungsgemeinschaft (DFG‐Grant BI 404/7|KR 2222/18). MeBo200 drilling was funded by the German Ministry of Education and Research (BMBF). Log‐seismic integrations and seismic inversions were carried out using an academic license to the HampsonRussell Software, Version HRS10.0.0. Some of the seismic interpretation was carried out with IHS Markit Kingdom software (version 2019). GC, JM, AO, JC and IP were supported by a Royal Society of New Zealand Marsden Grant, Number: NIW1603. JE was supported by the German Research Council (DFG SPP 527), Grant no. EL 978/1‐1. ES, BD and SC were supported by post cruise grants from the U.S. Science Support Program. Open access funding enabled and organized by Projekt DEAL. RV Tangaroa RV Sonne DV JOIDES Resolution

Publisher Copyright:
© 2021. The Authors.

Keywords

basal shear zone
core-log-seismic integration
Expedition 372
International Ocean Discovery Program (IODP)
shear strength
submarine landslide
Tuaheni Landslide Complex

ASJC Scopus subject areas

Geophysics
Geochemistry and Petrology
Earth and Planetary Sciences (miscellaneous)
Space and Planetary Science

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Cite this

Crutchley, G. J., Elger, J., Kuhlmann, J., Mountjoy, J. J., Orpin, A., Georgiopoulou, A., Carey, M. J., Dugan, B., Cardona, S., Han, S., Cook, A., Screaton, E. J., Pecher, I. A., Barnes, P., & Huhn, K. (2022). Investigating the Basal Shear Zone of the Submarine Tuaheni Landslide Complex, New Zealand: A Core-Log-Seismic Integration Study. Journal of Geophysical Research: Solid Earth, 127(1), Article e2021JB021997. https://doi.org/10.1029/2021JB021997

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abstract = "Although submarine landslides have been studied for decades, a persistent challenge is the integration of diverse geoscientific datasets to characterize failure processes. We present a core-log-seismic integration study of the Tuaheni Landslide Complex to investigate intact sediments beneath the undeformed seafloor as well as post-failure landslide deposits. Beneath the undeformed seafloor are coherent reflections underlain by a weakly-reflective and chaotic seismic unit. This chaotic unit is characterized by variable shear strength that correlates with density fluctuations. The basal shear zone of the Tuaheni landslide likely exploited one (or more) of the low shear strength intervals. Within the landslide deposits is a widespread “Intra-debris Reflector”, previously interpreted as the landslide's basal shear zone. This reflector is a subtle impedance drop around the boundary between upper and lower landslide units. However, there is no pronounced shear strength change across this horizon. Rather, there is a pronounced reduction in shear strength ∼10–15 m above the Intra-debris Reflector that presumably represents an induced weak layer that developed during failure. Free gas accumulates beneath some regions of the landslide and is widespread deeper in the sedimentary sequence, suggesting that free gas may have played a role in pre-conditioning the slope to failure. Additional pre-conditioning or failure triggers could have been seismic shaking and associated transient fluid pressure. Our study underscores the importance of detailed core-log-seismic integration approaches for investigating basal shear zone development in submarine landslides.",

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author = "Crutchley, {G. J.} and J. Elger and J. Kuhlmann and Mountjoy, {J. J.} and A. Orpin and A. Georgiopoulou and M.j. Carey and B. Dugan and S. Cardona and S. Han and A. Cook and Screaton, {E. J.} and Pecher, {I. A.} and P. Barnes and K. Huhn",

note = "Funding Information: We are grateful for excellent support from captains and crew of research voyages TAN1404 (), SO247 (), and IODP Expedition 372 (). This paper used data and images provided by IODP Expedition 372. We thank the science party and technical staff that assisted with sample and data acquisition. We also thank Tim Freudenthal (MARUM) and the MeBo200 team for their excellent support during drilling (SO247), and Tim for further post‐cruise advice about drilling parameters. We thank Felix Gross, Sebastian Krastel and Christoph B{\"o}ttner for valuable discussions about the Tuaheni landslide in recent years. We are grateful to Stefan B{\"u}nz and two anonymous reviewers for their insightful reviews that improved the quality of this paper, and to the Editor Yves Bernabe for handling this submission. Seismic data acquisition and processing was jointly funded by the New Zealand Ministry for Business Innovation and Employment (MBIE), NIWA and GNS Science Core funding and the Deutsche Forschungsgemeinschaft (DFG‐Grant BI 404/7|KR 2222/18). MeBo200 drilling was funded by the German Ministry of Education and Research (BMBF). Log‐seismic integrations and seismic inversions were carried out using an academic license to the HampsonRussell Software, Version HRS10.0.0. Some of the seismic interpretation was carried out with IHS Markit Kingdom software (version 2019). GC, JM, AO, JC and IP were supported by a Royal Society of New Zealand Marsden Grant, Number: NIW1603. JE was supported by the German Research Council (DFG SPP 527), Grant no. EL 978/1‐1. ES, BD and SC were supported by post cruise grants from the U.S. Science Support Program. Open access funding enabled and organized by Projekt DEAL. RV Tangaroa RV Sonne DV JOIDES Resolution Publisher Copyright: {\textcopyright} 2021. The Authors.",

year = "2022",

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doi = "10.1029/2021JB021997",

language = "English",

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journal = "Journal of Geophysical Research: Solid Earth",

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Crutchley, GJ, Elger, J, Kuhlmann, J, Mountjoy, JJ, Orpin, A, Georgiopoulou, A, Carey, MJ, Dugan, B, Cardona, S, Han, S, Cook, A, Screaton, EJ, Pecher, IA, Barnes, P & Huhn, K 2022, 'Investigating the Basal Shear Zone of the Submarine Tuaheni Landslide Complex, New Zealand: A Core-Log-Seismic Integration Study', Journal of Geophysical Research: Solid Earth, vol. 127, no. 1, e2021JB021997. https://doi.org/10.1029/2021JB021997

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T1 - Investigating the Basal Shear Zone of the Submarine Tuaheni Landslide Complex, New Zealand

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AU - Elger, J.

AU - Kuhlmann, J.

AU - Mountjoy, J. J.

AU - Orpin, A.

AU - Georgiopoulou, A.

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AU - Cardona, S.

AU - Han, S.

AU - Cook, A.

AU - Screaton, E. J.

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AU - Barnes, P.

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N2 - Although submarine landslides have been studied for decades, a persistent challenge is the integration of diverse geoscientific datasets to characterize failure processes. We present a core-log-seismic integration study of the Tuaheni Landslide Complex to investigate intact sediments beneath the undeformed seafloor as well as post-failure landslide deposits. Beneath the undeformed seafloor are coherent reflections underlain by a weakly-reflective and chaotic seismic unit. This chaotic unit is characterized by variable shear strength that correlates with density fluctuations. The basal shear zone of the Tuaheni landslide likely exploited one (or more) of the low shear strength intervals. Within the landslide deposits is a widespread “Intra-debris Reflector”, previously interpreted as the landslide's basal shear zone. This reflector is a subtle impedance drop around the boundary between upper and lower landslide units. However, there is no pronounced shear strength change across this horizon. Rather, there is a pronounced reduction in shear strength ∼10–15 m above the Intra-debris Reflector that presumably represents an induced weak layer that developed during failure. Free gas accumulates beneath some regions of the landslide and is widespread deeper in the sedimentary sequence, suggesting that free gas may have played a role in pre-conditioning the slope to failure. Additional pre-conditioning or failure triggers could have been seismic shaking and associated transient fluid pressure. Our study underscores the importance of detailed core-log-seismic integration approaches for investigating basal shear zone development in submarine landslides.

AB - Although submarine landslides have been studied for decades, a persistent challenge is the integration of diverse geoscientific datasets to characterize failure processes. We present a core-log-seismic integration study of the Tuaheni Landslide Complex to investigate intact sediments beneath the undeformed seafloor as well as post-failure landslide deposits. Beneath the undeformed seafloor are coherent reflections underlain by a weakly-reflective and chaotic seismic unit. This chaotic unit is characterized by variable shear strength that correlates with density fluctuations. The basal shear zone of the Tuaheni landslide likely exploited one (or more) of the low shear strength intervals. Within the landslide deposits is a widespread “Intra-debris Reflector”, previously interpreted as the landslide's basal shear zone. This reflector is a subtle impedance drop around the boundary between upper and lower landslide units. However, there is no pronounced shear strength change across this horizon. Rather, there is a pronounced reduction in shear strength ∼10–15 m above the Intra-debris Reflector that presumably represents an induced weak layer that developed during failure. Free gas accumulates beneath some regions of the landslide and is widespread deeper in the sedimentary sequence, suggesting that free gas may have played a role in pre-conditioning the slope to failure. Additional pre-conditioning or failure triggers could have been seismic shaking and associated transient fluid pressure. Our study underscores the importance of detailed core-log-seismic integration approaches for investigating basal shear zone development in submarine landslides.

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ER -

Investigating the Basal Shear Zone of the Submarine Tuaheni Landslide Complex, New Zealand: A Core-Log-Seismic Integration Study

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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