Integrated Geohazard Study Along the Krishna-Godavari Delta Slope, East Coast India

The continental slope of the Krishna-Godavari delta on the East coast of India exhibits a number of important geological phenomena which should be taken in consideration for offshore foundation design. A detailed geophysical and geotechnical investigation provided the data for an integrated study for the site selection for the foundation of an SBM oil terminal. The geophysical survey consisted of sparker, side scan sonar and bathymetry. Soil borings, including cone penetration testing, were performed at five alternative locations to a depth of 150 m.The soil profiles generally consist of normally consolidated very soft clays at mudline, becoming stiffer with depth. Geophysical data revealed two phases of faulting and mudsliding; an older phase (over 3000 years old) showing relict structures and a recent phase of mudsliding affecting the seabed topography.Stable and unstable foundation zones were identified.Stability calculations based on geotechnical properties of the soil profiles confirmed the delineation of these zones. Wave induced seabed loading analyses showed a mudslide risk for the original proposed SBM location and stable conditions for alternative sites.