Subaqueous Landslides as they Affect Bottom Structures
D. B. Prior, J. M. Coleman, J. N. Suhayda, L. E. Garrison, 1981. "Subaqueous Landslides as they Affect Bottom Structures", Offshore Geologic Hazards: A Short Course Presented at Rice University, May 2-3, 1981 for the Offshore Technology Conference, Arnold Bouma, Dwight Sangrey, James Coleman, David Prior, Anita Trippet, Wayne Dunlap, James Hooper
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The State and Federal lands offshore from the modern Mississippi River delta are highly productive of hydrocarbons, and there presently exist a large number of bottom-supported drilling and production platforms in water depths ranging from a few metres to several hundred metres. In addition, thousands of kilometres of pipelines connect these producing wells and production platforms to land-based processing and trunkline facilities. Since exploration began in this area, Several large plat-forms and many pipeline breaks have resulted from subaqueous sediment landslides. The major types of instabilities present have been mapped with a variety of seismic techniques. These maps, used in association with geotechnical tests, have permitted a comprehensive assessment of the mechanisms responsible for formation of the instabilities. The major types present are collapse depressions, bottleneck slides, and elongate mudslides and debris flows. The mechanisms responsible for the formation of these features are rapid sediment loading, buildup of excess pore pressures, cyclic wave loading, and localized oversteepening of the bottom. Structures and pipelines emplaced near or within a subaqueous landslide can experience loss of support, lateral displacement, or burial, depending upon the type and location of the landslide.
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Offshore Geologic Hazards: A Short Course Presented at Rice University, May 2-3, 1981 for the Offshore Technology Conference
Practically all parts of the United States continental shelves and some segments of the adjacent upper continental slopes are presently subject, or will be in the near future, to exploration and development. The same is true for many continental margins all over the world. Unless the potential influence of hazards is taken into account in the design, installation, and operation of any offshore structure, such structures can pose a threat that could result in pollution, damage, or loss of lives and equipment. This publication, written to accompany an AAPG Short Course, provides some kind of summary of current [at the time of writing] knowledge. Higher categories of geologic hazards as well as individual potentially hazardous geologic phenomena are described and discussed.