Landslide Frequency and Failure Mechanisms at NE Gela Basin (Strait of Sicily). Issue 11 (16th November 2017)

• Record Type: Journal Article
• Authors: Kuhlmann, J.; Asioli, A.; Trincardi, F.; Klügel, A.; Huhn, K.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 11(2017)
• Page Start: 2223
• Page End: 2243
• Publication Date: 2017-11-16
• Subjects: Gela Basin -- submarine mass movement -- recurrence -- weak layer -- seismicity -- volcanoclastic layer; Geomorphology -- Periodicals; 551.3
• DOI: 10.1002/2017JF004251
• Languages: English
• ISSNs: 2169-9003

Abstract

Abstract: Despite intense research by both academia and industry, the parameters controlling slope stability at continental margins are often speculated upon. Lack of core recovery and age control on failed sediments prevent the assessment of failure timing/frequency and the role of prefailure architecture as shaped by paleoenvironmental changes. This study uses an integrated chronological framework from two boreholes and complementary ultrahigh‐resolution acoustic profiling in order to assess (1) the frequency of submarine landsliding at the continental margin of NE Gela Basin and (2) the associated mechanisms of failure. Accurate age control was achieved through absolute radiocarbon dating and indirect dating relying on isotope stratigraphic and micropaleontological reconstructions. A total of nine major slope failure events have been recognized that occurred within the last 87 kyr (~10 kyr return frequency), though there is evidence for additional syndepositional, small‐scaled transport processes of lower volume. Preferential failure involves translational movement of mudflows along subhorizontal surfaces that are induced by sedimentological changes relating to prefailure stratal architecture. Along with sequence‐stratigraphic boundaries reflecting paleoenvironmental fluctuations, recovered core material suggests that intercalated volcaniclastic layers are key to the basal confinement and lateral movement of these events in the study area. Another major predisposing factor is given by rapid loading of fine‐grained homogenous strata and successive generation of excess pore pressure, as expressed by several fluid escape structures. Recurrent failure, however, requires repeated generation of favorable conditions, and seismic activity, though low if compared to many other Mediterranean settings, is shown to represent a legitimate trigger mechanism. Key Points: Nine major failure events occurred at NE Gela Basin within the last 87 kyr, predominantly during conditions of sea level fall or lowstand Foraminiferal records suggest additional, syndepositional processes of lower volume, counteracting the emplacement of larger landslides Preferential failure along subhorizontal weak layers (stratigraphic boundaries and volcanoclastic layers) likely triggered by seismicity