This paper assembles and reviews documents of past submarine slope instabilities. Those are large in size and highly various in nature. Most of those past events were caused by one of or combination of earthquakes, heavy wave loadings, rapid sedimentation. and others. This paper studies the mechanism of instability induced by these causes in detail with reference to results of laboratory and model testings.
Offshore developments have been activated only in the past few decades. Human land reclamation together with offshore mineral exploration have not experienced much natural disasters. Apparently submarine slope instability is one of those hazards. As new types of construction occurs in the sea. new kind of disasters are encountered. Hence. it is necessary to understand what happens in the sea but not to simply extend onshore experiences to the marine environment. This report is intended to meet with this need by reviewing past slope instabilities in the sea. It interprets them with knowledges obtained by laboratory soil testings and model tests.
Location of Submarine Instability There are many case-history reports of submarine slope instability and they have been assembled by. for example. Terzaghi (1956). Morgenstern (1967). and Schwarz (1982). The present authors make a similar attempt here. According to the present knowledge. instability is more likely to occur near the land because 1) soft soil deposits off river mouths. 2) slope inclination is greater near the land. 3) wave loading is important only near-shore. and 4) the earthquake activity is high along the perimeter of the Pacific Ocean. Since there could be an unknown cause of instability in the deep sea. further study should be conducted bottom of the ocean as well. Location of submarine slope instabilities however. on the bottom of the ocean as well
