Submarine landslides in the western margin of the Ulleung Basin, East Sea

We investigated submarine landslides along the western margin of the Ulleung Basin in the East Sea using sparker, subbottom profiler, and multibeam echosounder data. The analysis of bathymetric data indicates numerous U-shaped scars that initiate at water depths of similar to 600 m. The presence of large number of scarps in the source area suggests multiple failures rather than a single event. The individual scars are up to 60 m high and 4 km wide. Seismic data clearly image erosional headwalls and the basal sliding surface which is characterized by a prominent high-amplitude reflector. Chaotic-to-transparent seismic facies are seen immediately downslope of the headwall scarps; these chaotic facies represent landslide deposits of about 20 m in thickness. Earthquakes associated with tectonic activity were probably the primary triggering mechanism for these failures although other processes (i.e. gas charging and sea level fluctuations) may have acted as pre-conditioning factors.