Line length balancing to evaluate multi-phase submarine landslide development: an example from the Storegga Slide, Norway

Abstract

This study shows how simple structural restoration of a discrete submarine landslide lobe can be applied to large-scale, multi-phase examples to identify different phases of slide-lobe development and evaluate their mode of emplacement. We present the most detailed analysis performed to date on a zone of intense contractional deformation, historically referred to as the compression zone, from the giant, multi-phase Storegga Slide, offshore Norway. 2D and 3D seismic data and bathymetry data show that the zone of large-scale (>650 m thick) contractional deformation can be genetically linked updip with a zone of intense depletion across a distance of 135 km. Quantification of depletion and accumulation along a representative dip-section reveals that significant depletion in the proximal region is not accommodated in the relatively mild amount (c. 5%) of downdip shortening. Dip-section restoration indicates a later, separate stage of deformation may have involved removal of a significant volume of material as part of the final stages of the Storegga Slide, as opposed to the minor volumes reported in previous studies.

Seismic Diffraction Imaging to Characterize Mass‐Transport Complexes: Examples From the Gulf of Cadiz, South West Iberian Margin

“…Even MTCs that do preserve coherent, well‐imaged internal strata or internal geometry may benefit from the superior illumination of diffractions, especially at the discontinuous basal surface, lateral margins, and internal dislocation planes between slide blocks. Structural reconstruction to quantify strain distribution within MTCs relies on the proper imaging of such supraseismic scale interfaces (Bull & Cartwright, 2020; Steventon et al., 2019).…”

Seismic diffraction imaging to better characterise mass-transport complexes: examples from the Gulf of Cadiz, south west Iberian Margin

“…Even MTCs that do preserve coherent, well-imaged internal strata or internal geometry may benefit from the superior illumination of diffractions, especially at the discontinuous basal surface, lateral margins and internal dislocation planes between slide blocks. Structural reconstruction to quan--5-manuscript submitted to JGR: Solid Earth tify strain distribution within MTCs relies on the proper imaging of such supra-seismic scale interfaces (Steventon et al, 2019;Bull & Cartwright, 2020).…”