Micro-mechanics of failure planes

Ricarda Gatter | Marum


Almost 20 years ago, in July 1998, a tsunami struck Papua New Guinea and devastated three villages, causing the death of over 2200 people. In 1996, a landslide initiated offshore Finneidfjord, Norway, and removed a 250 m long section of the main north-south highway, due to the slide’s retrogressive behaviour. Although these events highlighted the importance of submarine landslide research, the potential hazard related to submarine landslides was already recognised in 1929. A large slide and the flow of sediment it generated broke telecommunication cables off Grand Banks. However, to enable the assessment and effective mitigation of this hazard, one needs to understand the underlying mechanisms first. What causes submarine landslides? What are the pre-conditioning factors and triggering mechanisms? How do submarine landslides behave during runout?

I focus on the factors that pre-condition slope failure. Many stud­ies have shown that basal fail­ure planes of sub­mar­ine land­slides co­in­cide with mech­an­ic­ally weaker lay­ers em­bed­ded within the slope strati­graphy. Pore pres­sure fluc­tu­ations along po­ten­tial weak lay­ers, e.g. em­bed­ded vol­canic ashes or fos­silifer­ous soils whose particles can break down un­der load­ing, can de­crease the shear strength of the sed­i­ments and hence, un­der­mine slope sta­bil­ity. Al­though many stud­ies have assessed the influence of sed­i­ment com­pos­i­tion on the phys­ical prop­er­ties and shear strength of sediments, the processes oc­cur­ring prior and dur­ing the ini­tial fail­ure are still poorly un­der­stood, as these can­not be dir­ectly ob­served or mon­itored. In this project, I will conduct a number of 3D numerical shear experiments, utilising granular simulation techniques (e.g., PFC3D), to investigate the failure processes at the initial stages of submarine landslides.


In a first step, I will compile a comprehensive dataset of µ-CT (micro- Computed Tomography) measurements of a wide range of sediment cores from different submarine landslides. These include cores from the Finneidfjord Slide (Norway), the AFEN Slide (UK), the Twin Slides (Italy), the Cap Blanc Slide (NW Africa), and the Tuaheni Slide (New Zealand). From this dataset, I will gather compositional and textural information of the material near the basal failure planes of the slides. The resulting information will directly act as input data for the numerical models.

By means of the 3D numerical simulations, which mimic geotechnical shear tests on a micro-(grain)-scaled level, I will investigate the fabric evolution of different materials under shearing with time. Of particular interest will be (A) a simplified ash and (B) a diatom sediment, and the changes in their shearing behaviour due to variations in the ash and diatom contents. The grain-scaled level is necessary in order to discern the spatial and temporal evolution of shear zones. Where does strain accumulate and where do basal failure planes form (above, inside, or below the weak layer)? This information is necessary to gain a deeper understanding of the failure mechanism and hence, the slide evolution itself.

Hosting institute
Working Group
  • Modelling of Sedimentation Processes
PDP Committee members:


Ricarda Gatter
PhD student – ESR 9
Katrin Huhn-Frehers
Principal Investigator – ESR 9, 11


Recap of 2019
ESR 9, General, Miscellaneous, News, Secondments | 2020-02-18

A year full of setbacks and progress, re-adjustments and developments, learning and new discoveries, but most importantly exciting science: Ricarda recalls her experiences of 2019.

Bologna Workshop – A discovery of turbidites or maybe more?
@ CNR-ISMAR Bologna, Italy (15 – 21 September 2019)

ESR 13, ESR 9, General, News | 2019-10-30

What are turbidites? What do they look like? And why should we care? Find out what our ESRs discovered during their third annual SLATE meeting and what else happened during the week in Bologna.

Impressions from the EGU 2019
@ Vienna, Austria (07 – 12 April 2019)

Conferences, ESR 1, ESR 12, ESR 13, ESR 14, ESR 15, ESR 2, ESR 3, ESR 4, ESR 5, ESR 6, ESR 7, ESR 8, ESR 9, News | 2019-07-23

ESRs share their experience at the EGU General Assembly 2019 hosted in Vienna, Austria. Posters, oral presentations, PICOs and much more.