Basement-controlled multiple slope collapses, Rockall Bank Slide Complex, NE Atlantic

Rheological considerations for the modelling of submarine sliding at Rockall Bank, NE Atlantic Ocean

“…31 Two distinct areas of failure escarpments (upper and lower slope regions) have been identified on the eastern margin of the Rockall Bank. 28 Due to its diverse scarp morphology, the upper slope was further subdivided into three distinct parts: the north, the south, and the central upper slope. 28 The two regions are separated by an elongate deep erosional moat near the base-of-slope, which traverses the area for 120 km and in parts can be as deep as 150 m. 28,29 The gradients of the slope are steep varying between 5 • and 10 • and in places can reach up to 15 • -20 • .…”

“…28 The two regions are separated by an elongate deep erosional moat near the base-of-slope, which traverses the area for 120 km and in parts can be as deep as 150 m. 28,29 The gradients of the slope are steep varying between 5 • and 10 • and in places can reach up to 15 • -20 • . 28 The scarps vary on sizes and heights. Despite some isolated retrogressive failure episodes, an overall non-retrogressive failure mechanism has been proposed based on observations of the scarp morphology and geometry.…”

“…2). The deposits of the RBSC show a run-out length of 120 km and a depositional width of 150 km 28,29 [ Fig. 2(c)].…”

“…35 In the past, there has been a high degree of uncertainty regarding the triggering mechanism of the failure and whether sliding occurred as a single failure episode or multiple successive or separate episodes of failure. 28 One hypothesis for the triggering mechanism suggests that sedimentation on top of abrupt pre-existing fault scarp topography at the upper part of the slope enhanced by strong bottom current activity removed support from the base-of-slope, leading to slope instability and subsequently failure. 28,29 Elliott et al concluded that the contourite drift dynamics in the basin acted as a substantial long term factor promoting slope instability.…”

“…28 One hypothesis for the triggering mechanism suggests that sedimentation on top of abrupt pre-existing fault scarp topography at the upper part of the slope enhanced by strong bottom current activity removed support from the base-of-slope, leading to slope instability and subsequently failure. 28,29 Elliott et al concluded that the contourite drift dynamics in the basin acted as a substantial long term factor promoting slope instability. 29 The sedimentation pattern has caused overloading of the upper part of the slope, whereas the contourite drift systems contributed to the erosion of the lower part of the slope and led to the formation of an elongate moat.…”