Gatter, Ricarda

My PhD pro­ject is part of the European Train­ing Net­work SLATE, which fo­cuses on the in­vest­ig­a­tion of sub­mar­ine land­slides and as­so­ci­ated geo­haz­ards. Sub­mar­ine land­slides are grav­it­a­tional mass move­ments of mar­ine sed­i­ment that can be ex­cep­tion­ally large, with volumes that far ex­ceed those of sub­aer­ial land­slides. They can dam­age very ex­pens­ive sub­sea in­fra­struc­ture such as pipelines used for oil and gas re­cov­ery or tele­com­mu­nic­a­tion cables, and gen­er­ated tsuna­mis in the past.

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 my pro­ject, I will fo­cus on quant­it­at­ively in­vest­ig­at­ing the key role of sed­i­ment tex­ture and fab­ric on strain loc­al­isa­tion, and the tem­poral and spa­tial evol­u­tion of shear zones on a grain-scaled level. I will con­duct 3D nu­mer­ical shear box ex­per­i­ments, util­ising gran­u­lar sim­u­la­tion tech­niques (e.g., PFC3D), to in­vest­ig­ate the fail­ure pro­cesses at the ini­tial stage of sub­mar­ine land­slides. These ex­per­i­ments will be com­bined with a com­pre­hens­ive data­set of mi­cro-CT meas­ure­ments and sed­i­mento­lo­gical ana­lyses on se­lec­ted cores from dif­fer­ent sub­mar­ine land­slides. From this data­set, in­form­a­tion about sed­i­ment com­pos­i­tion and tex­ture in the vi­cin­ity of the basal shear planes will be gathered. This in­form­a­tion will dir­ec­tly act as data in­put for the nu­mer­ical mod­els. The grain-scaled sim­u­la­tion ap­proach will en­able to gain a deeper un­der­stand­ing of the mi­cro-mech­an­ical pro­cesses within and along the basal fail­ure planes of sub­mar­ine slides and there­fore, the slide evol­u­tion it­self.

SLATE web page