The northeastern continental shelf of Korean peninsula in the East Sea records giant submarine landslides during the Late Quaternary
Abstract
Submarine landslides are worthy targets for research because they can act as agents of major mass transfer of material from the shallow to the deep sea. Moreover, they represent a major, previously little recognized geologic hazard to the coastal communities. This study investigates submarine landslides from a newly collected dataset constituted by multibeam echosounder, sub-bottom profiler, reflection seismic, and piston cores in the northeastern continental shelf of the Korean peninsula in the East Sea. Multibeam bathymetric data show at least 5 landslides initiating at water depths of 350 m, their headwalls are up to 300 m high and were formed by retrogressive failures associated with translational sliding. Moreover, chaotic-to-transparent seismic facies, on average 50 m thick and traceable seismically for a minimum of 1000 km2, are seen immediately downslope of the headwall scars and are interpreted as landslide deposits (i.e., slides/slumps, debris flow deposits). Piston cores taken from areas adjacent to the scars confirm the presence of landslide deposits that are characterized by mud clasts of variable size and shape. Ages of the slides are being determined, but preliminary core analysis suggests that they are older than ca. 15 ka. Individual landslides comprise volumes in the range of 2.5 -10 km3, cover 1000 km2 on the seafloor and have run out distances of up to 50 km from the source. Tectonic displacements exceeding 200 m in vertical throw are observed on several seismic profiles in close proximity of the headwall scars, some of which being very young. Hence we consider earthquakes associated with tectonic activity as the main triggering mechanism for these slides although other processes (i.e. high fluid pressures and weak layers) may have pre-conditioned sediments for failure. We consider that landslides with a volume of a 10 km3 at present would represent a significant hazard and risk to the densely populated coastal areas of the eastern Korean Peninsula.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMOS11F1466C
- Keywords:
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- 1641 Sea level change;
- GLOBAL CHANGEDE: 3002 Continental shelf and slope processes;
- MARINE GEOLOGY AND GEOPHYSICSDE: 3022 Marine sediments: processes and transport;
- MARINE GEOLOGY AND GEOPHYSICSDE: 3045 Seafloor morphology;
- geology;
- and geophysics;
- MARINE GEOLOGY AND GEOPHYSICS