Shear strength of siliciclastic sediments from passive and active margins (0-100 m below seafloor); insights into seismic strengthening

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doi: 10.1007/978-3-319-20979-1_17
Author(s): DeVore, Joshua R.; Sawyer, Derek E.
Author Affiliation(s): Primary:
Ohio State University, School of Earth Sciences, Columbus, OH, United States
Volume Title: Submarine mass movements and their consequences; 7th international symposium
Volume Author(s): Lamarche, Geoffroy, editor; Mountjoy, Joshu J.; Bull, Suzanne; Hubble, Thomas; Krastel, Sebastian; Lane, Emily M.; Micallef, Aaron; Moscardelli, Lorena; Mueller, Christof; Pecher, Ingo A.; Woelz, Susanne
Source: Advances in Natural and Technological Hazards Research, Vol.41, p.173-180; 7th symposium on Submarine mass movements and their consequences, Wellington, New Zealand, Nov. 1-4, 2015, edited by Geoffroy Lamarche, Joshu J. Mountjoy, Suzanne Bull, Thomas Hubble, Sebastian Krastel, Emily M. Lane, Aaron Micallef, Lorena Moscardelli, Christof Mueller, Ingo A. Pecher and Susanne Woelz. Publisher: Springer, Dordrecht, Netherlands. ISSN: 1878-9897. ISBN: 978-3-319-20979-1
Note: In English. 10 refs.; illus., incl. 1 table, sects.
Summary: Submarine geohazards threaten coastal communities and global economies. Submarine debris flows are the largest mass-wasting events observed on the Earth's surface, comprising of up to 50 % of basin fill. Further insight can be gained into these important processes by understanding in-situ preconditioning factors that lead to slope destabilization. We examine two locations from the International Ocean Discovery Program data archive to determine how external effects on sediment properties compare between passive margins and active margins. We select representative passive margin (Amazon Fan) and active margin sites (Nankai Trough), and analyse peak shear strength, void ratio, and composition from the uppermost 100 m below seafloor. This depth corresponds to a depth range in which most submarine mass movements originate. However, it is not appropriate to directly compare shear strength and void ratio of samples from different settings due to differing stress histories, sedimentary composition, and consolidation properties. We focus on ideal locations on both margin types that have solely undergone one-dimensional burial, no diagenesis/cementation, and no unroofing. We find that active margin sediments exhibit an increase in shear strength when compared to their passive margin counterparts, while void ratio tends to be higher on active margins. We are currently conducting a focused lab program to better understand compositional effects and determine the intrinsic properties of each site to more definitively normalize the in-situ sediment profiles. Our results suggest a potential link between shear strength and margin seismicity.
Year of Publication: 2016
Research Program: IODP2 International Ocean Discovery Program
Key Words: 23 Surficial Geology, Geomorphology; 30 Engineering Geology; Active margins; Amazon Fan; Atlantic Ocean; Coastal environment; Composition; Debris flows; Depth; Geologic hazards; Geomorphology; Hydrostatic pressure; International Ocean Discovery Program; Marine environment; Mass movements; Nankai Trough; Natural hazards; North Atlantic; North Pacific; Northwest Pacific; Ocean floors; Pacific Ocean; Passive margins; Plate tectonics; Pore pressure; Porosity; Sediments; Seismicity; Shear strength; Siliciclastics; Soil mechanics; Stress; Submarine environment; Tectonics; West Pacific
Record ID: 2016091735
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.

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