Signatures of Landslides in Coastal and Submarine Domain in Deltaic Environment in Eastern Continental Shelf of India, Bay of Bengal: Some Observations
Major part of the east coast of India, adjoining Bay of Bengal, is low-lying deltaic environment.Surveys picked up signatures of sliding and collapsing of sediments.Shallow seismic surveys off Godavari delta picked up a NW-SE trending structural discontinuity with down throw to the east, giving rise to seafloor instabilities.Mid-Holocene transgression coincided with the episodic neotectonic up liftment of the southern part led to the evolution of barrier-lagoon coast near Baruva.The southern part of erstwhile Dhanushkodi Township was subsided in 1948 AD.Sagar Island lies in the Ganga delta offshore.Its configuration from1851 to 1992 shows a substantial change.The northernmost tip got separated to form a new islet, perhaps due to submarine erosion by strong tidal current in this constricted zone, followed by landslide.Similarly, parts of intertidal zone of eastern coast of Sagar Island has collapsed and now submerged.Sediment collapsing along seabed is evident from the observation that 4m, 6m and 7m bathymetric contours arevery close to the coast, compared to year 2003 and 2007.Bathymetric contours off southwestern-most part of Sagar Island from 1m onward are compressed, indicating steeper sloperesulting slope failure.Parts of ancient clayey bottom, now submerged, also extend down the slope within overall matrix of sandy sediments due to underwater sliding and mass flow of sediments.Besides, there are signatures of submarine erosion, possibly resulting sliding of sediments along sandy shoals.The western bank of Pitts Creek has moved by about 400m westward.This having steeper slope near the sea mouth is being attacked by bottom friction due to northward divergence of littoral current moving from the west.Studies of samples from the eastern bank of Swatch of No Ground indicate that sediments might have been transported into the canyon floor by slumping or sliding.
Sagar Island landslides mass flow inner continental shelf Ganga delta
Bijan Kumar Saha Paramita Saha
School of Oceanographic Studies, Jadavpur University, 188, S.C.Mallik Road,Kolkata, India
国际会议
World Landslide Forum 3(第三届世界滑坡论坛)
北京
英文
633-636
2014-06-02（万方平台首次上网日期，不代表论文的发表时间）