Geologic Processes and Sea Floor Stability, Continental Shelf and Slope, Northwest Gulf of Mexico: A Systematic Approach to Identifying Geohazards
Henry L. Berryhill, Jr., 1981. "Geologic Processes and Sea Floor Stability, Continental Shelf and Slope, Northwest Gulf of Mexico: A Systematic Approach to Identifying Geohazards", 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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In an engineering sense, the geologic aspects of the sea floor are hazardous to man's activities when and where structures cannot be designed to withstand the combined stresses of the marine environment. In the most basic sense, geologic “hazards” relate directly to sea-floor stability, or the potential of the sea floor for significant movement that would be damaging to man-made structures placed on the sea floor. Judging the potential for movement requires descriptive details about the geologic conditions plus a quantitative understanding of the geologic and related oceanographic processes that are operative in the region on both periodic and long-term bases. Recognition and quantification of the geologic processes and their implications regarding potential hazards must stem from an understanding of the geologic history of the area in the recent past, which requires determining the relative rates and interactions of the two processes, sedimentation and tectonism, through time.
In an empirical sense certain features on the surface of the sea floor suggest unstable conditions: irregular or hummocky topography caused by the sliding or slumping of surficial sediments and diapiric movement, and offsets of the sea-floor surface caused by vertical slippage or faulting. The movements that created such features were a response or readjustment to some type of instability; the factors that caused the instability may have been localized or they may have been regional in scope. Furthermore, the movements indicated by the observed features may have been a one-time event that reestablished equilibrium for a long time to come, or they
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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.